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hep-ph/9306223
Ernest Ma
Ernest Ma
New Supersymmetric Two-Higgs-Doublet Structure at the Electroweak Energy Scale
4 pages, UCRHEP-T112, June 1993, to appear in Proc. of Festschrift in honor of Kameshwar Wali: New Directions in the Application of Symmetry Principles to Elementary Particle Theory
null
null
null
hep-ph
null
Contrary to common belief, the requirement that supersymmetry exists and that there are two Higgs doublets and no singlet at the electroweak energy scale does not necessarily result in the minimal supersymmetric standard model (MSSM). An interesting alternative is presented.
[ { "created": "Thu, 3 Jun 1993 22:35:41 GMT", "version": "v1" } ]
2007-05-23
[ [ "Ma", "Ernest", "" ] ]
Contrary to common belief, the requirement that supersymmetry exists and that there are two Higgs doublets and no singlet at the electroweak energy scale does not necessarily result in the minimal supersymmetric standard model (MSSM). An interesting alternative is presented.
hep-ph/0509083
Yue-Liang Wu
Yong-Liang Ma and Yue-Liang Wu (ITP-CAS)
Anomaly and Anomaly-Free Treatment of QFTs Based on Symmetry-preserving Loop Regularization
74 pages, Revtex, the ambiguities of anomaly caused by the trace of gamma matrices with gamma_5 and by the regularization schemes are further clarified. Minor corrections made without changing the conclusions
Int.J.Mod.Phys. A21 (2006) 6383-6456
10.1142/S0217751X0603309X
null
hep-ph
null
The triangle anomaly in massless and massive QED is investigated by adopting the symmetry-preserving loop regularization method proposed recently in \cite{LR}. The method is realized in the initial dimension of theory without modifying the original lagrangian, it preserves symmetries under non-Abelian gauge and Poincare transformations in spite of the existence of two intrinsic mass scales $M_c$ and $\mu_s$ which actually play the roles of UV- and IR-cut off respectively. The axialvector-vector-vector (AVV) triangle diagrams in massless and massive QED are evaluated explicitly by using the loop regularization. It is shown that when the momentum $k$ of external state is soft with $k^2 \ll \mu_s^2, m^2 $ ($m$ is the mass of loop fermions) and $ M_c \to \infty$, both massless and massive QED become anomaly free. The triangle anomaly is found to appear as quantum corrections in the case that $ m^2, \mu_s^2 \ll k^2 $ and $M_c \to \infty$. Especially, it is justified that in the massless QED with $\mu_s =0$ and $M_c\to \infty$, the triangle anomaly naturally exists as quantum effects in the axial-vector current when the ambiguity caused by the trace of gamma matrices with $\gamma_5$ is eliminated by simply using the definition of $\gamma_5$. It is explicitly demonstrated how the Ward identity anomaly of currents depends on the treatment for the trace of gamma matrices, which enables us to make a clarification whether the ambiguity of triangle anomaly is caused by the regularization scheme in the perturbation calculations or by the trace of gamma matrices with $\gamma_5$.
[ { "created": "Fri, 9 Sep 2005 07:51:59 GMT", "version": "v1" }, { "created": "Fri, 14 Apr 2006 04:49:56 GMT", "version": "v2" } ]
2009-11-11
[ [ "Ma", "Yong-Liang", "", "ITP-CAS" ], [ "Wu", "Yue-Liang", "", "ITP-CAS" ] ]
The triangle anomaly in massless and massive QED is investigated by adopting the symmetry-preserving loop regularization method proposed recently in \cite{LR}. The method is realized in the initial dimension of theory without modifying the original lagrangian, it preserves symmetries under non-Abelian gauge and Poincare transformations in spite of the existence of two intrinsic mass scales $M_c$ and $\mu_s$ which actually play the roles of UV- and IR-cut off respectively. The axialvector-vector-vector (AVV) triangle diagrams in massless and massive QED are evaluated explicitly by using the loop regularization. It is shown that when the momentum $k$ of external state is soft with $k^2 \ll \mu_s^2, m^2 $ ($m$ is the mass of loop fermions) and $ M_c \to \infty$, both massless and massive QED become anomaly free. The triangle anomaly is found to appear as quantum corrections in the case that $ m^2, \mu_s^2 \ll k^2 $ and $M_c \to \infty$. Especially, it is justified that in the massless QED with $\mu_s =0$ and $M_c\to \infty$, the triangle anomaly naturally exists as quantum effects in the axial-vector current when the ambiguity caused by the trace of gamma matrices with $\gamma_5$ is eliminated by simply using the definition of $\gamma_5$. It is explicitly demonstrated how the Ward identity anomaly of currents depends on the treatment for the trace of gamma matrices, which enables us to make a clarification whether the ambiguity of triangle anomaly is caused by the regularization scheme in the perturbation calculations or by the trace of gamma matrices with $\gamma_5$.
hep-ph/9906457
Leonard S. Kisslinger
L.S. Kisslinger, M. Aw, A. Harey and O. Linsuain (Carnegie Mellon University)
Quark propagator, instantons and gluon propagator
Latex file, no figures
Phys.Rev. C60 (1999) 065204
10.1103/PhysRevC.60.065204
null
hep-ph
null
The Schwinger-Dyson formalism is used to check the consistency of instanton model solutions for the quark propagator with recent models of confining gluon propagators. We find that the models are not consistent. A major discrepancy is the absence of a vector condensate in the instanton model that is present in the solutions with nonperturbative confining gluons.
[ { "created": "Tue, 22 Jun 1999 17:40:46 GMT", "version": "v1" } ]
2009-10-31
[ [ "Kisslinger", "L. S.", "", "Carnegie Mellon\n University" ], [ "Aw", "M.", "", "Carnegie Mellon\n University" ], [ "Harey", "A.", "", "Carnegie Mellon\n University" ], [ "Linsuain", "O.", "", "Carnegie Mellon\n University" ] ]
The Schwinger-Dyson formalism is used to check the consistency of instanton model solutions for the quark propagator with recent models of confining gluon propagators. We find that the models are not consistent. A major discrepancy is the absence of a vector condensate in the instanton model that is present in the solutions with nonperturbative confining gluons.
1808.02037
Yongcheng Wu
Ning Chen, Tao Han, Shufang Su, Wei Su, Yongcheng Wu
Type-II 2HDM under the Precision Measurements at the $Z$-pole and a Higgs Factory
32 pages, 13 figures; v2: refs added, matches published version
null
10.1007/JHEP03(2019)023
PITT-PACC-1808
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Future precision measurements of the Standard Model (SM) parameters at the proposed $Z$-factories and Higgs factories may have significant impacts on new physics beyond the Standard Model in the electroweak sector. We illustrate this by focusing on the Type-II two Higgs doublet model (Type-II 2HDM). The contributions from the heavy Higgs bosons at the tree-level and at the one-loop level are included in a full model parameter space. We perform a multiple variable global fit and study the extent to which the parameters of non-alignment and non-degenerate masses can be probed by the precision measurements. We find that the allowed parameter ranges are tightly constrained by the future Higgs precision measurements, especially for small and large values of $\tan\beta$. Indirect limits on the masses of heavy Higgs can be obtained, which can be complementary to the direct searches of the heavy Higgs bosons at hadron colliders. We also find that the expected accuracies at the $Z$-pole and at a Higgs factory are quite complementary in constraining mass splittings of heavy Higgs bosons. The typical results are $|\cos(\beta-\alpha)| < 0.008, |\Delta m_\Phi | < 200\ {\rm GeV}$, and $\tan\beta \sim 0.2 - 5$. The reaches from CEPC, FCC-ee and ILC are also compared, for both Higgs and $Z$-pole precision measurements.
[ { "created": "Mon, 6 Aug 2018 18:00:04 GMT", "version": "v1" }, { "created": "Fri, 1 Mar 2019 13:50:00 GMT", "version": "v2" } ]
2019-03-27
[ [ "Chen", "Ning", "" ], [ "Han", "Tao", "" ], [ "Su", "Shufang", "" ], [ "Su", "Wei", "" ], [ "Wu", "Yongcheng", "" ] ]
Future precision measurements of the Standard Model (SM) parameters at the proposed $Z$-factories and Higgs factories may have significant impacts on new physics beyond the Standard Model in the electroweak sector. We illustrate this by focusing on the Type-II two Higgs doublet model (Type-II 2HDM). The contributions from the heavy Higgs bosons at the tree-level and at the one-loop level are included in a full model parameter space. We perform a multiple variable global fit and study the extent to which the parameters of non-alignment and non-degenerate masses can be probed by the precision measurements. We find that the allowed parameter ranges are tightly constrained by the future Higgs precision measurements, especially for small and large values of $\tan\beta$. Indirect limits on the masses of heavy Higgs can be obtained, which can be complementary to the direct searches of the heavy Higgs bosons at hadron colliders. We also find that the expected accuracies at the $Z$-pole and at a Higgs factory are quite complementary in constraining mass splittings of heavy Higgs bosons. The typical results are $|\cos(\beta-\alpha)| < 0.008, |\Delta m_\Phi | < 200\ {\rm GeV}$, and $\tan\beta \sim 0.2 - 5$. The reaches from CEPC, FCC-ee and ILC are also compared, for both Higgs and $Z$-pole precision measurements.
2307.04861
Adrian Thompson
James B. Dent, Bhaskar Dutta, Adrian Thompson
Bragg-Primakoff Axion Photoconversion in Crystal Detectors
15 pages, 9 figures (including appendix); updated references
null
null
MI-HET-804
hep-ph
http://creativecommons.org/publicdomain/zero/1.0/
Axions and axion-like pseudoscalar particles with dimension-5 couplings to photons exhibit coherent Primakoff scattering with ordered crystals at keV energy scales, making for a natural detection technique in searches for solar axions. We find that there are large suppressive corrections, potentially greater than a factor of $\mathcal{O}(10^3)$, to the coherent enhancement when taking into account absorption of the final state photon. This effect has already been accounted for in light-shining-through-wall experiments through the language of Darwin classical diffraction, but is missing from the literature in the context of solar axion searches that use a matrix element approach. We extend the treatment of the event rate with a heuristic description of absorption effects to bridge the gap between these two languages. Furthermore, we explore the Borrmann effect of anomalous absorption in lifting some of the event rate suppression by increasing the coherence length of the conversion. We study this phenomenon in Ge, NaI, and CsI crystal experiments and its impact on the the projected sensitivities of SuperCDMS, LEGEND, and SABRE to the solar axion parameter space. Lastly, we comment on the reach of multi-tonne scale crystal detectors and strategies to maximize the discovery potential of experimental efforts in this vein.
[ { "created": "Mon, 10 Jul 2023 19:17:26 GMT", "version": "v1" }, { "created": "Wed, 12 Jul 2023 16:28:49 GMT", "version": "v2" } ]
2023-07-13
[ [ "Dent", "James B.", "" ], [ "Dutta", "Bhaskar", "" ], [ "Thompson", "Adrian", "" ] ]
Axions and axion-like pseudoscalar particles with dimension-5 couplings to photons exhibit coherent Primakoff scattering with ordered crystals at keV energy scales, making for a natural detection technique in searches for solar axions. We find that there are large suppressive corrections, potentially greater than a factor of $\mathcal{O}(10^3)$, to the coherent enhancement when taking into account absorption of the final state photon. This effect has already been accounted for in light-shining-through-wall experiments through the language of Darwin classical diffraction, but is missing from the literature in the context of solar axion searches that use a matrix element approach. We extend the treatment of the event rate with a heuristic description of absorption effects to bridge the gap between these two languages. Furthermore, we explore the Borrmann effect of anomalous absorption in lifting some of the event rate suppression by increasing the coherence length of the conversion. We study this phenomenon in Ge, NaI, and CsI crystal experiments and its impact on the the projected sensitivities of SuperCDMS, LEGEND, and SABRE to the solar axion parameter space. Lastly, we comment on the reach of multi-tonne scale crystal detectors and strategies to maximize the discovery potential of experimental efforts in this vein.
1105.1379
Shufang Su
Vikram Rentala (Univ. of Arizona, UC Irvine), William Shepherd (UC Irvine), Shufang Su (Univ. of Arizona, UC Irvine)
A Simplified Model Approach to Same-sign Dilepton Resonances
25 pages, 7 figures
Phys.Rev.D84:035004,2011
10.1103/PhysRevD.84.035004
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We discuss same-sign dilepton resonances in the simplified model approach. The relevant $SU(3}_Q^J$ quantum numbers are $1_2^{0,1,2}$. For simplicity, we only consider a spin 0 scalar, which is typically referred to as a doubly charged Higgs in the literature. We consider the three simplest cases where the doubly charged Higgs resides in a singlet, doublet or triplet $SU(2)_L$ representation. We discuss production and decay of such a doubly charged Higgs, summarize the current direct search limits, and obtain mass limits in the cases of singlet and doublet for the first time. We also present a complete set of updated indirect search limits. We study the discovery potential at the Large Hadron Collider (LHC) with center of mass energies 7 and 14 TeV for the dominant Drell-Yan pair production with $H^{\pm\pm}$ decay in the $ee$ and $\mu\mu$ channels. We find that at 7 TeV, the LHC with 10 $fb^{-1}$ luminosity can probe mass of the doubly charged Higgs up to 380 GeV assuming 100% decay to leptons. At 14 TeV, the LHC with 100 $fb^{-1}$ luminosity can reach a mass of up to 800 GeV.
[ { "created": "Fri, 6 May 2011 20:02:06 GMT", "version": "v1" } ]
2011-08-12
[ [ "Rentala", "Vikram", "", "Univ. of Arizona, UC Irvine" ], [ "Shepherd", "William", "", "UC\n Irvine" ], [ "Su", "Shufang", "", "Univ. of Arizona, UC Irvine" ] ]
We discuss same-sign dilepton resonances in the simplified model approach. The relevant $SU(3}_Q^J$ quantum numbers are $1_2^{0,1,2}$. For simplicity, we only consider a spin 0 scalar, which is typically referred to as a doubly charged Higgs in the literature. We consider the three simplest cases where the doubly charged Higgs resides in a singlet, doublet or triplet $SU(2)_L$ representation. We discuss production and decay of such a doubly charged Higgs, summarize the current direct search limits, and obtain mass limits in the cases of singlet and doublet for the first time. We also present a complete set of updated indirect search limits. We study the discovery potential at the Large Hadron Collider (LHC) with center of mass energies 7 and 14 TeV for the dominant Drell-Yan pair production with $H^{\pm\pm}$ decay in the $ee$ and $\mu\mu$ channels. We find that at 7 TeV, the LHC with 10 $fb^{-1}$ luminosity can probe mass of the doubly charged Higgs up to 380 GeV assuming 100% decay to leptons. At 14 TeV, the LHC with 100 $fb^{-1}$ luminosity can reach a mass of up to 800 GeV.
hep-ph/9803206
Ernest Ma
Ernest Ma (UC Riverside)
Neutrino Masses and Anomalous Interactions
7 pages, no figure, latex, sprocl.sty, talk at XVI Autumn School and Workshop on Fermion Masses, Mixing and CP Violation, Lisbon, Oct 97
null
null
UCRHEP-T217 (Feb 98)
hep-ph
null
The interplay between neutrino masses and the interactions of neutrinos with matter is discussed with an eye to extending the latter to include possible new interactions. This conjecture may resolve the conundrum posed by the present experimental data on neutrino oscillations which suggest the existence of four neutrinos, whereas Z decay and Big Bang Nucleosynthesis allow only three. The case of a possible sterile neutrino is also briefly discussed.
[ { "created": "Sat, 28 Feb 1998 20:42:22 GMT", "version": "v1" } ]
2007-05-23
[ [ "Ma", "Ernest", "", "UC Riverside" ] ]
The interplay between neutrino masses and the interactions of neutrinos with matter is discussed with an eye to extending the latter to include possible new interactions. This conjecture may resolve the conundrum posed by the present experimental data on neutrino oscillations which suggest the existence of four neutrinos, whereas Z decay and Big Bang Nucleosynthesis allow only three. The case of a possible sterile neutrino is also briefly discussed.
1710.03658
Glenn Robbins
G. Robbins, F. Mahmoudi, A. Arbey, M. Boudaud
Dark matter and LHC: Complementarities and limitations
5 pages, 3 figures. Contribution to the proceedings of the European Physical Society Conference on High Energy Physics (EPS-HEP 2017)
null
null
CERN-TH-2017-203
hep-ph astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It is well known that dark matter density measurements, indirect and direct detection experiments, importantly complement the LHC in setting strong constraints on new physics scenarios. Yet, dark matter searches are subject to limitations which need to be considered for realistic analyses. For illustration, we explore the parameter space of the phenomenological MSSM and discuss the interplay of the constraints from dark matter searches and the LHC, and analyse the impact of the astrophysical uncertainties in some detail.
[ { "created": "Tue, 10 Oct 2017 15:32:08 GMT", "version": "v1" } ]
2017-10-11
[ [ "Robbins", "G.", "" ], [ "Mahmoudi", "F.", "" ], [ "Arbey", "A.", "" ], [ "Boudaud", "M.", "" ] ]
It is well known that dark matter density measurements, indirect and direct detection experiments, importantly complement the LHC in setting strong constraints on new physics scenarios. Yet, dark matter searches are subject to limitations which need to be considered for realistic analyses. For illustration, we explore the parameter space of the phenomenological MSSM and discuss the interplay of the constraints from dark matter searches and the LHC, and analyse the impact of the astrophysical uncertainties in some detail.
1805.09768
Arlene Cristina Aguilar
A. C. Aguilar and C. T. Figueiredo
Effects of the ghost sector in gluon mass dynamics
4 pages, 3 figures. Poster presented at the XIV International Workshop on Hadron Physics, Florianopolis, Brazil, 18-23 March 2018
null
null
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work, we investigate the effects of the ghost sector on the dynamical mass generation for the gauge boson of a pure Yang-Mills theory. The generation of a dynamical mass for the gluon is realized by the Schwinger mechanism, which is triggered by the existence of longitudinally coupled massless poles in the fundamental vertices of the theory. The appearance of such poles occurs by purely dynamical reasons and is governed by a set of Bethe-Salpeter equations. In previous studies, only the presence of massless poles in the background-gauge three-gluon vertex was considered. Here, we include the possibility for such poles to appear also in the corresponding ghost-gluon vertex. Then, we solve the resulting Bethe-Salpeter system, which reveals that the contribution associated with the poles of the ghost-gluon vertex is suppressed with respect to those originating from the three-gluon vertex.
[ { "created": "Thu, 24 May 2018 16:40:54 GMT", "version": "v1" } ]
2018-05-25
[ [ "Aguilar", "A. C.", "" ], [ "Figueiredo", "C. T.", "" ] ]
In this work, we investigate the effects of the ghost sector on the dynamical mass generation for the gauge boson of a pure Yang-Mills theory. The generation of a dynamical mass for the gluon is realized by the Schwinger mechanism, which is triggered by the existence of longitudinally coupled massless poles in the fundamental vertices of the theory. The appearance of such poles occurs by purely dynamical reasons and is governed by a set of Bethe-Salpeter equations. In previous studies, only the presence of massless poles in the background-gauge three-gluon vertex was considered. Here, we include the possibility for such poles to appear also in the corresponding ghost-gluon vertex. Then, we solve the resulting Bethe-Salpeter system, which reveals that the contribution associated with the poles of the ghost-gluon vertex is suppressed with respect to those originating from the three-gluon vertex.
2104.03191
Francesco Giuli Dr.
Francesco Giuli
Impact of A0 data on the Higgs boson production cross section at the LHC
4 pages, 8 Figures, 1 Table, proceeding of the Moriond QCD 2021 conference
null
null
null
hep-ph hep-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this talk, we present a way to improve the accuracy of theoretical predictions for Higgs boson production cross sections at the LHC using the measurements of lepton angular distributions. In this regards, we exploit the sensitivity of the lepton angular coefficient associated with the longitudinal Z-boson polarization to the parton density function (PDF) for gluons resolved from the incoming protons, in order to constrain the Higgs boson cross section from gluon fusion processes. We find that high-statistics determinations of the longitudinally polarized angular coefficient at the LHC Run 3 and high-luminosity HL-LHC improve the PDF systematics of the Higgs boson cross section predictions by 50% over a broad range of Higgs boson rapidities. This study has been conducted using the open-source fitting framework xFitter. This talk refers to the following paper: arXiv:2012.10298[hep-ph]
[ { "created": "Wed, 7 Apr 2021 15:31:32 GMT", "version": "v1" } ]
2021-04-08
[ [ "Giuli", "Francesco", "" ] ]
In this talk, we present a way to improve the accuracy of theoretical predictions for Higgs boson production cross sections at the LHC using the measurements of lepton angular distributions. In this regards, we exploit the sensitivity of the lepton angular coefficient associated with the longitudinal Z-boson polarization to the parton density function (PDF) for gluons resolved from the incoming protons, in order to constrain the Higgs boson cross section from gluon fusion processes. We find that high-statistics determinations of the longitudinally polarized angular coefficient at the LHC Run 3 and high-luminosity HL-LHC improve the PDF systematics of the Higgs boson cross section predictions by 50% over a broad range of Higgs boson rapidities. This study has been conducted using the open-source fitting framework xFitter. This talk refers to the following paper: arXiv:2012.10298[hep-ph]
2107.13037
Francesco Giovanni Celiberto
Francesco Giovanni Celiberto, Dmitry Yu. Ivanov, Mohammed. M. A. Mohammed, Alessandro Papa
High-energy resummation in inclusive hadroproduction of Higgs plus jet
Submission to SciPost
SciPost Phys. Proc. 8, 039 (2022)
10.21468/SciPostPhysProc.8
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Using the standard Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach, with partial inclusion of next-to-leading order effects, we propose the inclusive hadroproduction of a Higgs boson and of a jet, featuring large transverse momenta and well separated in rapidity, as a new channel to probe the BFKL dynamics. Predictions are presented for cross-sections and azimuthal angle correlations in different kinematics configurations for the final-state transverse momenta. We find that the large energy scales provided by the emission of a Higgs boson stabilize the BFKL series.
[ { "created": "Tue, 27 Jul 2021 18:38:39 GMT", "version": "v1" }, { "created": "Tue, 2 Aug 2022 00:17:47 GMT", "version": "v2" } ]
2022-08-03
[ [ "Celiberto", "Francesco Giovanni", "" ], [ "Ivanov", "Dmitry Yu.", "" ], [ "Mohammed", "Mohammed. M. A.", "" ], [ "Papa", "Alessandro", "" ] ]
Using the standard Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach, with partial inclusion of next-to-leading order effects, we propose the inclusive hadroproduction of a Higgs boson and of a jet, featuring large transverse momenta and well separated in rapidity, as a new channel to probe the BFKL dynamics. Predictions are presented for cross-sections and azimuthal angle correlations in different kinematics configurations for the final-state transverse momenta. We find that the large energy scales provided by the emission of a Higgs boson stabilize the BFKL series.
1502.04005
Orfeu Bertolami
Orfeu Bertolami, Hodjat Mariji
A Phase-Space Noncommutative Picture of Nuclear Matter
13 pages, 2 tables, 2 figures
null
10.1142/S0217751X15501912
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Noncommutative features are introduced into a relativistic quantum field theory model of nuclear matter, the quantum hadrodynamics-I nuclear model (QHD-I). It is shown that the nuclear matter equation of state (NMEoS) depends on the fundamental momentum scale, $\eta$, introduced by the phase-space noncommutativity (NC). Although it is found that NC geometry does not affect the nucleon fields up to $O(\eta^2)$, it affects the energy density, the pressure and other derivable quantities of the NMEoS, such as the nucleon \textit{effective mass}. Under the conditions of saturation of the symmetric NM, the estimated value for the noncommutative parameter is $\sqrt{\eta}=0.014 MeV/c$.
[ { "created": "Fri, 13 Feb 2015 14:38:25 GMT", "version": "v1" } ]
2015-12-09
[ [ "Bertolami", "Orfeu", "" ], [ "Mariji", "Hodjat", "" ] ]
Noncommutative features are introduced into a relativistic quantum field theory model of nuclear matter, the quantum hadrodynamics-I nuclear model (QHD-I). It is shown that the nuclear matter equation of state (NMEoS) depends on the fundamental momentum scale, $\eta$, introduced by the phase-space noncommutativity (NC). Although it is found that NC geometry does not affect the nucleon fields up to $O(\eta^2)$, it affects the energy density, the pressure and other derivable quantities of the NMEoS, such as the nucleon \textit{effective mass}. Under the conditions of saturation of the symmetric NM, the estimated value for the noncommutative parameter is $\sqrt{\eta}=0.014 MeV/c$.
1607.03262
Carlos Roberto Pena Ruano
A. Donini, P. Hern\'andez, C. Pena, F. Romero-L\'opez
Non-leptonic kaon decays at large $N_c$
Expanded discussion. Conclusions unchanged. Published version
Phys. Rev. D 94, 114511 (2016)
10.1103/PhysRevD.94.114511
IFIC/16-39, IFT-UAM/CSIC-16-063, FTUAM-16-26
hep-ph hep-lat
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the scaling with the number of colours, $N_c$, of the weak amplitudes mediating kaon mixing and decay. We evaluate the amplitudes of the two relevant current-current operators on the lattice for $N_c=3-7$. We conclude that the subleading $1/N_c$ corrections in $\hat{B}_K$ are small, but those in the $K \rightarrow \pi\pi$ amplitudes are large and fully anti-correlated in the $I=0, 2$ isospin channels. We briefly comment on the implications for the $\Delta I=1/2$ rule.
[ { "created": "Tue, 12 Jul 2016 08:48:14 GMT", "version": "v1" }, { "created": "Wed, 4 Jan 2017 11:51:08 GMT", "version": "v2" } ]
2017-01-05
[ [ "Donini", "A.", "" ], [ "Hernández", "P.", "" ], [ "Pena", "C.", "" ], [ "Romero-López", "F.", "" ] ]
We study the scaling with the number of colours, $N_c$, of the weak amplitudes mediating kaon mixing and decay. We evaluate the amplitudes of the two relevant current-current operators on the lattice for $N_c=3-7$. We conclude that the subleading $1/N_c$ corrections in $\hat{B}_K$ are small, but those in the $K \rightarrow \pi\pi$ amplitudes are large and fully anti-correlated in the $I=0, 2$ isospin channels. We briefly comment on the implications for the $\Delta I=1/2$ rule.
2108.02748
Fabio L. Braghin
Fabio L Braghin
Strangeness content of the pion in the U(3) Nambu-Jona-Lasinio model
30 pages, 8 figures, new comments, discussions and estimates for the strangeness content of the pion, including an estimate based on the pi-eta mixing. Few misprints/mistakes corrected
null
10.1088/1361-6471/ac4d79
null
hep-ph nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The Nambu-Jona-Lasinio model is considered with flavor-dependent coupling constants $G_{ij} \left[ ( \bar{\psi} \lambda_i \psi ) ( \bar{\psi} \lambda_j \psi )+ ( \bar{\psi} i\gamma_5 \lambda_i \psi ) ( \bar{\psi} i \gamma_5\lambda_j \psi )\right]$ for $i,j=0,1..N_f^2-1$, and $N_f=3$. A self consistent calculation of quark effective masses and coupling constants is performed making the strange quark effective mass to vary considerably. Quantum mechanical mixings between up, down and strange constituent quarks yields a strangeness content of the light u and d quarks constituent and of the pion. Different types of estimates for the strangeness contribution for the pion mass are provided. Mixing type interactions, $G_{i\neq j}$, induce the light mesons mixings and estimates for the $\pi^0-\eta$ and $\eta-\eta'$ mixings are provided. The $\eta-\pi^0$ mixing is argued to be an indication of the strangeness content of the pion.
[ { "created": "Thu, 5 Aug 2021 17:29:20 GMT", "version": "v1" }, { "created": "Fri, 3 Sep 2021 17:58:42 GMT", "version": "v2" }, { "created": "Fri, 7 Jan 2022 11:43:49 GMT", "version": "v3" }, { "created": "Mon, 27 Mar 2023 18:10:33 GMT", "version": "v4" }, { "crea...
2023-07-11
[ [ "Braghin", "Fabio L", "" ] ]
The Nambu-Jona-Lasinio model is considered with flavor-dependent coupling constants $G_{ij} \left[ ( \bar{\psi} \lambda_i \psi ) ( \bar{\psi} \lambda_j \psi )+ ( \bar{\psi} i\gamma_5 \lambda_i \psi ) ( \bar{\psi} i \gamma_5\lambda_j \psi )\right]$ for $i,j=0,1..N_f^2-1$, and $N_f=3$. A self consistent calculation of quark effective masses and coupling constants is performed making the strange quark effective mass to vary considerably. Quantum mechanical mixings between up, down and strange constituent quarks yields a strangeness content of the light u and d quarks constituent and of the pion. Different types of estimates for the strangeness contribution for the pion mass are provided. Mixing type interactions, $G_{i\neq j}$, induce the light mesons mixings and estimates for the $\pi^0-\eta$ and $\eta-\eta'$ mixings are provided. The $\eta-\pi^0$ mixing is argued to be an indication of the strangeness content of the pion.
hep-ph/9909523
Sanghyeon Chang
Sanghyeon Chang and Masahiro Yamaguchi
Fate of Gravitons in Warped Extra Dimension
9 pages, no figures, a typo in Eq.(15) is fixed
null
null
TU-575
hep-ph
null
Interaction of bulk gravitons to Standard Model particles is examined in the scenario of warped extra dimension. It is found that the length of the extra dimension is of physical importance as it determines the decay widths of graviton Kaluza-Klein modes. We show that cosmology as well as collider signals of the Kaluza-Klein modes are very different for different choices of the length of the fifth dimension.
[ { "created": "Tue, 28 Sep 1999 05:23:57 GMT", "version": "v1" }, { "created": "Thu, 30 Sep 1999 11:29:54 GMT", "version": "v2" } ]
2007-05-23
[ [ "Chang", "Sanghyeon", "" ], [ "Yamaguchi", "Masahiro", "" ] ]
Interaction of bulk gravitons to Standard Model particles is examined in the scenario of warped extra dimension. It is found that the length of the extra dimension is of physical importance as it determines the decay widths of graviton Kaluza-Klein modes. We show that cosmology as well as collider signals of the Kaluza-Klein modes are very different for different choices of the length of the fifth dimension.
1704.01894
Damian Ejlli
Damian Ejlli
Milli-charged fermion vacuum polarization in cosmic magnetic fields and generation of CMB elliptic polarization
31 pages and 11 figures. Typos corrected, additional references included. Additional text about nature of cosmic magnetic field added in the conclusion section. Version to be published in Physical Review D
Phys. Rev. D 96, 023540 (2017)
10.1103/PhysRevD.96.023540
null
hep-ph astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The contribution of one loop milli-charged fermion vacuum polarization in cosmic magnetic field to the cosmic microwave background (CMB) polarization is considered. Exact and perturbative solution of the density matrix equations of motion in terms of the Stokes parameters are presented. For linearly polarized CMB at decoupling time, it is shown that propagation of CMB photons in cosmic magnetic field would generate elliptic polarization (circular and linear) of the CMB due to milli-charged fermion vacuum polarization. Analytic expressions for the degree of circular polarization and rotation angle of polarization plane of the CMB are presented. Depending on the ratio of milli-charged fermion relative charge to mass, $\epsilon/m_\epsilon$, and CMB observation frequency, it is shown that the acquired CMB degree of circular polarization could be of the order of magnitude $P_C(T_0)\sim 10^{-10}- 10^{-6}$ in the best scenario. The effect studied generates CMB polarization even in the case when the CMB is initially in thermal equilibrium. Limits on the magnetic field amplitude due to prior decoupling CMB polarization are presented.
[ { "created": "Thu, 6 Apr 2017 15:40:49 GMT", "version": "v1" }, { "created": "Mon, 10 Jul 2017 13:17:37 GMT", "version": "v2" } ]
2017-08-02
[ [ "Ejlli", "Damian", "" ] ]
The contribution of one loop milli-charged fermion vacuum polarization in cosmic magnetic field to the cosmic microwave background (CMB) polarization is considered. Exact and perturbative solution of the density matrix equations of motion in terms of the Stokes parameters are presented. For linearly polarized CMB at decoupling time, it is shown that propagation of CMB photons in cosmic magnetic field would generate elliptic polarization (circular and linear) of the CMB due to milli-charged fermion vacuum polarization. Analytic expressions for the degree of circular polarization and rotation angle of polarization plane of the CMB are presented. Depending on the ratio of milli-charged fermion relative charge to mass, $\epsilon/m_\epsilon$, and CMB observation frequency, it is shown that the acquired CMB degree of circular polarization could be of the order of magnitude $P_C(T_0)\sim 10^{-10}- 10^{-6}$ in the best scenario. The effect studied generates CMB polarization even in the case when the CMB is initially in thermal equilibrium. Limits on the magnetic field amplitude due to prior decoupling CMB polarization are presented.
1008.2895
Alexey Nefediev
Yu.S.Kalashnikova, A.V.Nefediev (ITEP, Moscow)
X(3872) as a 1D2 charmonium state
RevTeX4, 4 pages, two referenced added, a few minor amends in the text, version to appear as Brief Report in Phys.Rev.D
Phys.Rev.D82:097502,2010
10.1103/PhysRevD.82.097502
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The 1D2 charmonium assignment for the X(3872) meson is considered, as prompted by a recent result from the BABAR Collaboration, favouring 2-+ quantum numbers for the X. It is shown that established properties of the X(3872) are in a drastic conflict with the 1D2 c-anti-c assignment.
[ { "created": "Tue, 17 Aug 2010 13:41:11 GMT", "version": "v1" }, { "created": "Tue, 26 Oct 2010 18:07:28 GMT", "version": "v2" } ]
2010-12-23
[ [ "Kalashnikova", "Yu. S.", "", "ITEP, Moscow" ], [ "Nefediev", "A. V.", "", "ITEP, Moscow" ] ]
The 1D2 charmonium assignment for the X(3872) meson is considered, as prompted by a recent result from the BABAR Collaboration, favouring 2-+ quantum numbers for the X. It is shown that established properties of the X(3872) are in a drastic conflict with the 1D2 c-anti-c assignment.
hep-ph/0008134
Evgeny Akhmedov
E.Kh. Akhmedov
Floquet theory of neutrino oscillations in the earth
LaTeX, 28 pages, 8 eps figures. Contribution to the special issue of Yad. Fiz. dedicated to the memory of A.B. Migdal
Phys.Atom.Nucl.64:787-801,2001; Yad.Fiz.64:851-865,2001
10.1134/1.1378869
FISIST/8-2000/CFIF
hep-ph astro-ph hep-th
null
We review the Floquet theory of linear differential equations with periodic coefficients and discuss its applications to neutrino oscillations in matter of periodically varying density. In particular, we consider parametric resonance in neutrino oscillations which can occur in such media, and discuss implications for oscillations of neutrinos traversing the earth and passing through the earth's core.
[ { "created": "Mon, 14 Aug 2000 16:58:28 GMT", "version": "v1" } ]
2008-11-26
[ [ "Akhmedov", "E. Kh.", "" ] ]
We review the Floquet theory of linear differential equations with periodic coefficients and discuss its applications to neutrino oscillations in matter of periodically varying density. In particular, we consider parametric resonance in neutrino oscillations which can occur in such media, and discuss implications for oscillations of neutrinos traversing the earth and passing through the earth's core.
1203.2764
Dmitry Zhuridov Dr.
Dmitry V. Zhuridov
Testing Localization in Neutrino Oscillations
5 pages, 2 figures; minor changes, prepared for submission to JHEP
null
null
null
hep-ph hep-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The neutrino wave packet localization in short-baseline neutrino oscillation experiments, such as MiniBooNE, is investigated. It is shown that the transition from localization to delocalization may be observed for large neutrino mass splitting of order 1 eV, e.g., in theories with sterile neutrinos.
[ { "created": "Tue, 13 Mar 2012 11:05:40 GMT", "version": "v1" }, { "created": "Fri, 16 Mar 2012 15:33:15 GMT", "version": "v2" } ]
2012-03-19
[ [ "Zhuridov", "Dmitry V.", "" ] ]
The neutrino wave packet localization in short-baseline neutrino oscillation experiments, such as MiniBooNE, is investigated. It is shown that the transition from localization to delocalization may be observed for large neutrino mass splitting of order 1 eV, e.g., in theories with sterile neutrinos.
hep-ph/0203261
John F. Beacom
G. Barenboim, J.F. Beacom, L. Borissov, B. Kayser
CPT Violation and the Nature of Neutrinos
10 pages, 1 figure
Phys.Lett.B537:227-232,2002
10.1016/S0370-2693(02)01947-0
FERMILAB-Pub-02/014-T, FERMILAB-Pub-02/014-A
hep-ph nucl-th
null
In order to accommodate the neutrino oscillation signals from the solar, atmospheric, and LSND data, a sterile fourth neutrino is generally invoked, though the fits to the data are becoming more and more constrained. However, it has recently been shown that the data can be explained with only three neutrinos, if one invokes CPT violation to allow different masses and mixing angles for neutrinos and antineutrinos. We explore the nature of neutrinos in such CPT-violating scenarios. Majorana neutrino masses are allowed, but in general, there are no longer Majorana neutrinos in the conventional sense. However, CPT-violating models still have interesting consequences for neutrinoless double beta decay. Compared to the usual case, while the larger mass scale (from LSND) may appear, a greater degree of suppression can also occur.
[ { "created": "Wed, 27 Mar 2002 23:49:02 GMT", "version": "v1" } ]
2008-11-26
[ [ "Barenboim", "G.", "" ], [ "Beacom", "J. F.", "" ], [ "Borissov", "L.", "" ], [ "Kayser", "B.", "" ] ]
In order to accommodate the neutrino oscillation signals from the solar, atmospheric, and LSND data, a sterile fourth neutrino is generally invoked, though the fits to the data are becoming more and more constrained. However, it has recently been shown that the data can be explained with only three neutrinos, if one invokes CPT violation to allow different masses and mixing angles for neutrinos and antineutrinos. We explore the nature of neutrinos in such CPT-violating scenarios. Majorana neutrino masses are allowed, but in general, there are no longer Majorana neutrinos in the conventional sense. However, CPT-violating models still have interesting consequences for neutrinoless double beta decay. Compared to the usual case, while the larger mass scale (from LSND) may appear, a greater degree of suppression can also occur.
1512.07165
Ivan Ni\v{s}and\v{z}i\'c
A. E. C\'arcamo Hern\'andez and Ivan Nisandzic
LHC diphoton 750 GeV resonance as an indication of $SU(3)_c\times SU(3)_L\times U(1)_X$ gauge symmetry
13 pages, 1 figure. Substantially improved version
null
null
DO-TH 15/19, USM-TH-339
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The LHC collaborations ATLAS and CMS recently reported on the excess of the events in the diphoton final states at the invariant mass of about $750~ \text{GeV}$. In this article we speculate on the possibility that the excess arises from the neutral CP-even component $\phi$ of the scalar triplet $ \Phi $ of the $SU(3)_{c}\times SU(3)_{L}\times U(1)_{X}$ $(3\text{-}3\text{-} 1)$ model that has a $U(1)_{X}$ charge equal to $X=-1/3$ and acquires a vacuum expectation value larger than the electroweak symmetry breaking scale. The interactions of the scalar field $\phi$ to the photon- and gluon-pairs are mediated by the virtual vector-like fermions which appear as components of the anomaly-free chiral fermion representations of the $3\text{ -}3\text{-}1$ gauge group.
[ { "created": "Tue, 22 Dec 2015 17:28:32 GMT", "version": "v1" }, { "created": "Fri, 20 May 2016 01:12:34 GMT", "version": "v2" } ]
2016-05-23
[ [ "Hernández", "A. E. Cárcamo", "" ], [ "Nisandzic", "Ivan", "" ] ]
The LHC collaborations ATLAS and CMS recently reported on the excess of the events in the diphoton final states at the invariant mass of about $750~ \text{GeV}$. In this article we speculate on the possibility that the excess arises from the neutral CP-even component $\phi$ of the scalar triplet $ \Phi $ of the $SU(3)_{c}\times SU(3)_{L}\times U(1)_{X}$ $(3\text{-}3\text{-} 1)$ model that has a $U(1)_{X}$ charge equal to $X=-1/3$ and acquires a vacuum expectation value larger than the electroweak symmetry breaking scale. The interactions of the scalar field $\phi$ to the photon- and gluon-pairs are mediated by the virtual vector-like fermions which appear as components of the anomaly-free chiral fermion representations of the $3\text{ -}3\text{-}1$ gauge group.
hep-ph/0011385
Mar Bastero
M. Bastero-Gil and S. F. King
Leptogenesis in a Realistic Supersymmetric Model of Inflation with a Low Reheat Temperature
17 page, latex, 1 eps fig
Phys.Rev. D63 (2001) 123509
10.1103/PhysRevD.63.123509
SNS-PH/00-17
hep-ph
null
We discuss leptogenesis in a realistic supersymmetric model of inflation with a low reheat temperature 1-10 GeV. The lepton asymmetry is generated by a decaying right handed sneutrino, which is produced after inflation during preheating. The inflationary model is based on a simple variant of the Next-to-Minimal Supersymmetric Standard model (NMSSM) which solves the \mu problem, called \phiNMSSM, where the additional singlet \phi plays the role of the inflaton in hybrid (or inverted hybrid) type models. The model is invariant under an approximate Peccei-Quinn symmetry which also solves the strong CP problem, and leads to an invisible axion with interesting cosmological consequences. We show how the baryon number of the universe and the nature of cold dark matter are determined by the same parameters controlling the strong CP problem, the \mu problem and the neutrino masses and mixing angles.
[ { "created": "Thu, 30 Nov 2000 09:29:02 GMT", "version": "v1" } ]
2009-10-31
[ [ "Bastero-Gil", "M.", "" ], [ "King", "S. F.", "" ] ]
We discuss leptogenesis in a realistic supersymmetric model of inflation with a low reheat temperature 1-10 GeV. The lepton asymmetry is generated by a decaying right handed sneutrino, which is produced after inflation during preheating. The inflationary model is based on a simple variant of the Next-to-Minimal Supersymmetric Standard model (NMSSM) which solves the \mu problem, called \phiNMSSM, where the additional singlet \phi plays the role of the inflaton in hybrid (or inverted hybrid) type models. The model is invariant under an approximate Peccei-Quinn symmetry which also solves the strong CP problem, and leads to an invisible axion with interesting cosmological consequences. We show how the baryon number of the universe and the nature of cold dark matter are determined by the same parameters controlling the strong CP problem, the \mu problem and the neutrino masses and mixing angles.
1707.09690
Yanrui Liu
Shao-Zhou Jiang, Yan-Rui Liu, Hong-Qian Wang
Chiral Lagrangians with $\Delta(1232)$ to one loop
23 pages,8 tables. Less terms are found with more constraints. Version accepted by PRD
Phys. Rev. D 97, 014002 (2018)
10.1103/PhysRevD.97.014002
null
hep-ph hep-lat nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We construct the Lorentz-invariant chiral Lagrangians up to the order $\mathcal{O}(p^4)$ by including $\Delta(1232)$ as an explicit degree of freedom. A full one-loop investigation on processes involving $\Delta(1232)$ can be performed with them. For the $\pi\Delta\Delta$ Lagrangian, one obtains 38 independent terms at the order $\mathcal{O}(p^3)$ and 318 independent terms at the order $\mathcal{O}(p^4)$. For the $\pi N\Delta$ Lagrangian, we get 33 independent terms at the order $\mathcal{O}(p^3)$ and 218 independent terms at the order $\mathcal{O}(p^4)$. The heavy baryon projection is also briefly discussed.
[ { "created": "Mon, 31 Jul 2017 00:56:06 GMT", "version": "v1" }, { "created": "Thu, 14 Dec 2017 20:30:13 GMT", "version": "v2" } ]
2018-01-10
[ [ "Jiang", "Shao-Zhou", "" ], [ "Liu", "Yan-Rui", "" ], [ "Wang", "Hong-Qian", "" ] ]
We construct the Lorentz-invariant chiral Lagrangians up to the order $\mathcal{O}(p^4)$ by including $\Delta(1232)$ as an explicit degree of freedom. A full one-loop investigation on processes involving $\Delta(1232)$ can be performed with them. For the $\pi\Delta\Delta$ Lagrangian, one obtains 38 independent terms at the order $\mathcal{O}(p^3)$ and 318 independent terms at the order $\mathcal{O}(p^4)$. For the $\pi N\Delta$ Lagrangian, we get 33 independent terms at the order $\mathcal{O}(p^3)$ and 218 independent terms at the order $\mathcal{O}(p^4)$. The heavy baryon projection is also briefly discussed.
hep-ph/9411209
Alexei Gladyshev
A.V.Gladyshev, D.I.Kazakov
Renormalization Group Improved Radiative Corrections to the Supersymmetric Higgs Boson Masses
10 PAGES, 1 FIGURE ENCLOSED, LATEX
Mod.Phys.Lett. A10 (1995) 3129-3138
10.1142/S0217732395003288
JINR E2-94-400
hep-ph
null
The one-loop radiative corrections to the Higgs boson potential in the MSSM, originating from the top quark and squark loops, are summed in the leading log approximation using the renormalization group. The RG improved effective potential is minimized and the corrections to the CP-odd and CP-even Higgs boson masses are calculated. The resulting masses exhibit smoother top mass dependence than those calculated without RG summation. We have also found that for preferable values of the top mass the light Higgs mass does not exceed 100 GeV.
[ { "created": "Wed, 2 Nov 1994 18:23:10 GMT", "version": "v1" } ]
2015-06-25
[ [ "Gladyshev", "A. V.", "" ], [ "Kazakov", "D. I.", "" ] ]
The one-loop radiative corrections to the Higgs boson potential in the MSSM, originating from the top quark and squark loops, are summed in the leading log approximation using the renormalization group. The RG improved effective potential is minimized and the corrections to the CP-odd and CP-even Higgs boson masses are calculated. The resulting masses exhibit smoother top mass dependence than those calculated without RG summation. We have also found that for preferable values of the top mass the light Higgs mass does not exceed 100 GeV.
0901.3766
Ethan Neil
Thomas Appelquist, George T. Fleming, Ethan T. Neil
Lattice Study of Conformal Behavior in SU(3) Yang-Mills Theories
37 pages, 7 figures. v2: assorted minor updates and corrections
Phys.Rev.D79:076010,2009
10.1103/PhysRevD.79.076010
null
hep-ph hep-lat
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Using lattice simulations, we study the extent of the conformal window for an SU(3) gauge theory with N_f Dirac fermions in the fundamental representation. We extend our recently reported work, describing the general framework and the lattice simulations in more detail. We find that the theory is conformal in the infrared for N_f = 12, governed by an infrared fixed point, whereas the N_f = 8 theory exhibits confinement and chiral symmetry breaking. We therefore conclude that the low end of the conformal window N_f^c lies in the range 8 <= N_f^c <= 12. We discuss open questions and the potential relevance of the present work to physics beyond the standard model.
[ { "created": "Fri, 23 Jan 2009 20:59:34 GMT", "version": "v1" }, { "created": "Fri, 15 May 2009 20:29:03 GMT", "version": "v2" } ]
2010-04-21
[ [ "Appelquist", "Thomas", "" ], [ "Fleming", "George T.", "" ], [ "Neil", "Ethan T.", "" ] ]
Using lattice simulations, we study the extent of the conformal window for an SU(3) gauge theory with N_f Dirac fermions in the fundamental representation. We extend our recently reported work, describing the general framework and the lattice simulations in more detail. We find that the theory is conformal in the infrared for N_f = 12, governed by an infrared fixed point, whereas the N_f = 8 theory exhibits confinement and chiral symmetry breaking. We therefore conclude that the low end of the conformal window N_f^c lies in the range 8 <= N_f^c <= 12. We discuss open questions and the potential relevance of the present work to physics beyond the standard model.
hep-ph/0607073
Kenji Fukushima
Kenji Fukushima
A description of the target wave-function encoded in the source terms
7 pages, 2 figures, typos corrected and references added
null
null
null
hep-ph
null
We argue that the gauge invariant source terms in the formalism of the Color Glass Condensate (CGC) should properly describe the target wave-function if the microscopic structure is concerned in the regime where the parton distribution is not quite dense. The quantum property of color charge density is incorporated in the quantum weight function defined with the source terms. We sketch that the logarithmic source terms encompass a meaningful picture of the microscopic structure of the target wave-function.
[ { "created": "Fri, 7 Jul 2006 00:14:49 GMT", "version": "v1" }, { "created": "Wed, 12 Jul 2006 20:55:42 GMT", "version": "v2" } ]
2007-05-23
[ [ "Fukushima", "Kenji", "" ] ]
We argue that the gauge invariant source terms in the formalism of the Color Glass Condensate (CGC) should properly describe the target wave-function if the microscopic structure is concerned in the regime where the parton distribution is not quite dense. The quantum property of color charge density is incorporated in the quantum weight function defined with the source terms. We sketch that the logarithmic source terms encompass a meaningful picture of the microscopic structure of the target wave-function.
0903.2415
Bjoern Duling
Michaela E. Albrecht, Monika Blanke, Andrzej J. Buras, Bjoern Duling, Katrin Gemmler
Electroweak and Flavour Structure of a Warped Extra Dimension with Custodial Protection
74 pages, 2 figures. clarifying comments and references added, version to be published in JHEP
JHEP 0909:064,2009
10.1088/1126-6708/2009/09/064
TUM-HEP-711/09, MPP-2009-17
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present the electroweak and flavour structure of a model with a warped extra dimension and the bulk gauge group SU(3) x SU(2)_L x SU(2)_R x P_LR x U(1)_X. The presence of SU(2)_R implies an unbroken custodial symmetry in the Higgs system allowing to eliminate large contributions to the T parameter, whereas the P_LR symmetry and the enlarged fermion representations provide a custodial symmetry for flavour diagonal and flavour changing couplings of the SM Z boson to left-handed down-type quarks. We diagonalise analytically the mass matrices of charged and neutral gauge bosons including the first KK modes. We present the mass matrices for quarks including heavy KK modes and discuss the neutral and charged currents involving light and heavy fields. We give the corresponding complete set of Feynman rules in the unitary gauge.
[ { "created": "Fri, 13 Mar 2009 16:06:29 GMT", "version": "v1" }, { "created": "Tue, 8 Sep 2009 12:00:25 GMT", "version": "v2" } ]
2014-11-18
[ [ "Albrecht", "Michaela E.", "" ], [ "Blanke", "Monika", "" ], [ "Buras", "Andrzej J.", "" ], [ "Duling", "Bjoern", "" ], [ "Gemmler", "Katrin", "" ] ]
We present the electroweak and flavour structure of a model with a warped extra dimension and the bulk gauge group SU(3) x SU(2)_L x SU(2)_R x P_LR x U(1)_X. The presence of SU(2)_R implies an unbroken custodial symmetry in the Higgs system allowing to eliminate large contributions to the T parameter, whereas the P_LR symmetry and the enlarged fermion representations provide a custodial symmetry for flavour diagonal and flavour changing couplings of the SM Z boson to left-handed down-type quarks. We diagonalise analytically the mass matrices of charged and neutral gauge bosons including the first KK modes. We present the mass matrices for quarks including heavy KK modes and discuss the neutral and charged currents involving light and heavy fields. We give the corresponding complete set of Feynman rules in the unitary gauge.
1207.2193
Jen-Chieh Peng
Jen-Chieh Peng and Wen-Chen Chang
Nucleon sea and the five-quark components
8 pages, 4 figures. Plenary talk at the QNP2012 Conference
null
null
null
hep-ph nucl-ex nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We generalize the approach of Brodsky {\it et al.} for the intrinsic charm quark distribution in the nucleons to the light-quark sector involving intrinsic $\bar u, \bar d, s$ and $\bar s$ sea quarks. We compare the calculations with the existing $\bar d - \bar u$, $s + \bar s$, and $\bar u + \bar d - s -\bar s$ data. The good agreement between the theory and the data is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons. The probabilities for the $|uudu\bar{u}>$, $|uudd\bar{d}>$ and $|uuds\bar{s}>$ Fock states are also extracted.
[ { "created": "Mon, 9 Jul 2012 22:28:25 GMT", "version": "v1" } ]
2012-07-11
[ [ "Peng", "Jen-Chieh", "" ], [ "Chang", "Wen-Chen", "" ] ]
We generalize the approach of Brodsky {\it et al.} for the intrinsic charm quark distribution in the nucleons to the light-quark sector involving intrinsic $\bar u, \bar d, s$ and $\bar s$ sea quarks. We compare the calculations with the existing $\bar d - \bar u$, $s + \bar s$, and $\bar u + \bar d - s -\bar s$ data. The good agreement between the theory and the data is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons. The probabilities for the $|uudu\bar{u}>$, $|uudd\bar{d}>$ and $|uuds\bar{s}>$ Fock states are also extracted.
1805.01642
Divya Sachdeva
Mathew Thomas Arun, Debajyoti Choudhury, Divya Sachdeva
Living Orthogonally: Quasi-universal Extra Dimensions
43 pages, 5 figures, accepted for publication in JHEP
null
10.1007/JHEP01(2019)230
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The minimal Universal Extra Dimension scenario is highly constrained owing to opposing constraints from the observed relic density on the one hand, and the non-observation of new states at the LHC on the other. Simple extensions in five-dimensions can only postpone the inevitable. Here, we propose a six-dimensional alternative with the key feature being that the SM quarks and leptons are localized on orthogonal directions whereas gauge bosons traverse the entire bulk. Several different realizations of electroweak symmetry breaking are possible, while maintaining agreement with low energy observables. This model is not only consistent with all the current constraints opposing the minimal Universal Extra Dimension scenario but also allows for a multi-TeV dark matter particle without the need for any fine-tuning. In addition, it promises a plethora of new signatures at the LHC and other future experiments.
[ { "created": "Fri, 4 May 2018 08:06:52 GMT", "version": "v1" }, { "created": "Mon, 28 Jan 2019 06:13:38 GMT", "version": "v2" } ]
2019-02-20
[ [ "Arun", "Mathew Thomas", "" ], [ "Choudhury", "Debajyoti", "" ], [ "Sachdeva", "Divya", "" ] ]
The minimal Universal Extra Dimension scenario is highly constrained owing to opposing constraints from the observed relic density on the one hand, and the non-observation of new states at the LHC on the other. Simple extensions in five-dimensions can only postpone the inevitable. Here, we propose a six-dimensional alternative with the key feature being that the SM quarks and leptons are localized on orthogonal directions whereas gauge bosons traverse the entire bulk. Several different realizations of electroweak symmetry breaking are possible, while maintaining agreement with low energy observables. This model is not only consistent with all the current constraints opposing the minimal Universal Extra Dimension scenario but also allows for a multi-TeV dark matter particle without the need for any fine-tuning. In addition, it promises a plethora of new signatures at the LHC and other future experiments.
hep-ph/9511311
Fredrick Olness
Ruibin Meng, Fredrick I. Olness, Davison E. Soper
Semi-Inclusive Deeply Inelastic Scattering at Small q_T
RevTeX format, 32 pages, 15 uuencoded figures with epsf.tex
Phys.Rev.D54:1919-1935,1996
10.1103/PhysRevD.54.1919
CTEQ-409
hep-ph
null
Measurement of the distribution of hadronic energy in the final state in deeply inelastic electron scattering at HERA can provide a good test of our understanding of perturbative QCD. For this purpose, we consider the energy distribution function, which can be computed without needing final state parton fragmentation functions. We compute this distribution function for finite transverse momentum q_T at order alpha_s, and use the results to sum the perturbation series to obtain a result valid for both large and small values of transverse momentum.
[ { "created": "Tue, 14 Nov 1995 04:08:49 GMT", "version": "v1" } ]
2014-11-17
[ [ "Meng", "Ruibin", "" ], [ "Olness", "Fredrick I.", "" ], [ "Soper", "Davison E.", "" ] ]
Measurement of the distribution of hadronic energy in the final state in deeply inelastic electron scattering at HERA can provide a good test of our understanding of perturbative QCD. For this purpose, we consider the energy distribution function, which can be computed without needing final state parton fragmentation functions. We compute this distribution function for finite transverse momentum q_T at order alpha_s, and use the results to sum the perturbation series to obtain a result valid for both large and small values of transverse momentum.
hep-ph/0408190
Richard Galik
Richard S. Galik
Quarkonium Production and Decay
Invited talk at the XXIV Physics in Collisions Conference (PIC04), Boston, USA, June 2004, 14 pages, LaTeX, 11 eps figures. PSN SUNT09. Several typographical errors and incorrect spellings corrected
null
null
null
hep-ph
null
With new data sets, recently completed analyses and renewed interest, there has been significant progress in addressing existing questions about quarkonia production and decay ... but also new questions and new confrontation with theory. Some highlights include the firm establishment of the eta_c^' and of the ``missing'' psi^' decays to pseudoscalar-vector final states, improved information on the nature of the psi(3770), and the observation of a new, puzzling charmonium-like state at 3872 MeV.
[ { "created": "Tue, 17 Aug 2004 18:25:39 GMT", "version": "v1" }, { "created": "Wed, 1 Sep 2004 18:27:47 GMT", "version": "v2" } ]
2007-05-23
[ [ "Galik", "Richard S.", "" ] ]
With new data sets, recently completed analyses and renewed interest, there has been significant progress in addressing existing questions about quarkonia production and decay ... but also new questions and new confrontation with theory. Some highlights include the firm establishment of the eta_c^' and of the ``missing'' psi^' decays to pseudoscalar-vector final states, improved information on the nature of the psi(3770), and the observation of a new, puzzling charmonium-like state at 3872 MeV.
hep-ph/0005186
James Hetherington
B.C. Allanach, J.P.J. Hetherington, M.A. Parker, B.R. Webber
Naturalness Reach of the Large Hadron Collider in Minimal Supergravity
16 pages, 7 figures. Version 2: significant numerical changes due to improved accuracy of fine-tuning calculation. Section added on discussion of radiative electroweak breaking constraint
JHEP 0008:017,2000
10.1088/1126-6708/2000/08/017
null
hep-ph hep-ex
null
We re-analyse the prospects of discovering supersymmetry at the LHC, in order to re-express coverage in terms of a fine-tuning parameter and to extend the analysis to scalar masses (m_0) above 2 TeV. We use minimal supergravity (mSUGRA) unification assumptions for the SUSY breaking parameters. The discovery reach at high m_0 is of renewed interest because this region has recently been found to have a focus point, leading to relatively low fine-tuning, and because it remains uncertain how much of the region can be ruled out due to lack of radiative electroweak symmetry breaking. The best fine tuning reach is found in a mono-leptonic channel, where for mu>0, A_0=0 and tan beta=10 (within the focus point region), and a top mass of 174 GeV, all points in mSUGRA with m_0 < 4000 GeV, with a fine tuning measure up to 210 (500) are covered by the search, where the definition of fine-tuning excludes (includes) the contribution from the top Yukawa coupling. Even for arbitrarily high m_0, mSUGRA can be discovered through gaugino events, provided the gaugino mass parameter M_1/2 < 460 GeV. In this region, the mono-leptonic channel still provides the best reach.
[ { "created": "Thu, 18 May 2000 11:17:23 GMT", "version": "v1" }, { "created": "Fri, 28 Jul 2000 13:35:21 GMT", "version": "v2" } ]
2016-09-06
[ [ "Allanach", "B. C.", "" ], [ "Hetherington", "J. P. J.", "" ], [ "Parker", "M. A.", "" ], [ "Webber", "B. R.", "" ] ]
We re-analyse the prospects of discovering supersymmetry at the LHC, in order to re-express coverage in terms of a fine-tuning parameter and to extend the analysis to scalar masses (m_0) above 2 TeV. We use minimal supergravity (mSUGRA) unification assumptions for the SUSY breaking parameters. The discovery reach at high m_0 is of renewed interest because this region has recently been found to have a focus point, leading to relatively low fine-tuning, and because it remains uncertain how much of the region can be ruled out due to lack of radiative electroweak symmetry breaking. The best fine tuning reach is found in a mono-leptonic channel, where for mu>0, A_0=0 and tan beta=10 (within the focus point region), and a top mass of 174 GeV, all points in mSUGRA with m_0 < 4000 GeV, with a fine tuning measure up to 210 (500) are covered by the search, where the definition of fine-tuning excludes (includes) the contribution from the top Yukawa coupling. Even for arbitrarily high m_0, mSUGRA can be discovered through gaugino events, provided the gaugino mass parameter M_1/2 < 460 GeV. In this region, the mono-leptonic channel still provides the best reach.
0706.3079
Shao-Ming Wang
Wang Shao-Ming, Han Liang, Ma Wen-Gan, Zhang Ren-You, and Jiang Yi
Revisiting the QCD corrections to the R-parity violating processes $p\bar{p}/pp \to e\mu+X$
9 pages, 8 figures
Chin.Phys.Lett.25:58,2008
10.1088/0256-307X/25/1/017
null
hep-ph
null
We present the theoretical predictions up to QCD NLO for the cross section of high-mass electron-muon pair production at the Tevatron and the LHC, considering only the dominant contributions from the third-generation sneutrino. The dependence of the renormalization and factorization scales on the total cross section, and the effects on the K-factor due to the uncertainty of parton distribution function(PDF) have been carefully investigated. By considering soft-gluon resummation effects to all order in $\alpha_s$ of leading logarithm, we present the transverse momentum distributions of the final $e\mu$ pair.
[ { "created": "Thu, 21 Jun 2007 03:45:46 GMT", "version": "v1" }, { "created": "Tue, 13 Nov 2007 09:14:33 GMT", "version": "v2" }, { "created": "Tue, 20 Nov 2007 07:15:41 GMT", "version": "v3" } ]
2011-08-31
[ [ "Shao-Ming", "Wang", "" ], [ "Liang", "Han", "" ], [ "Wen-Gan", "Ma", "" ], [ "Ren-You", "Zhang", "" ], [ "Yi", "Jiang", "" ] ]
We present the theoretical predictions up to QCD NLO for the cross section of high-mass electron-muon pair production at the Tevatron and the LHC, considering only the dominant contributions from the third-generation sneutrino. The dependence of the renormalization and factorization scales on the total cross section, and the effects on the K-factor due to the uncertainty of parton distribution function(PDF) have been carefully investigated. By considering soft-gluon resummation effects to all order in $\alpha_s$ of leading logarithm, we present the transverse momentum distributions of the final $e\mu$ pair.
1609.00609
Xian-Qiao Yu
Xian-Qiao Yu
Parton distribution of nucleon and nuclear EMC effect in a statistical model
7 pages, 4 figures
null
null
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the parton distribution of nucleon and nuclear EMC effect in a statistical model. We find when we choose the parameters appropriately, the predictions given by pure statistical laws can fit the experimental data well in most range of $x$, this reveal statistical law play an important role in the parton distribution of nucleon.
[ { "created": "Sat, 16 Jan 2016 04:23:30 GMT", "version": "v1" } ]
2016-09-05
[ [ "Yu", "Xian-Qiao", "" ] ]
We study the parton distribution of nucleon and nuclear EMC effect in a statistical model. We find when we choose the parameters appropriately, the predictions given by pure statistical laws can fit the experimental data well in most range of $x$, this reveal statistical law play an important role in the parton distribution of nucleon.
hep-ph/0304070
Alejandro Szynkman
L.N. Epele, D. Gomez Dumm, A. Szynkman
Annihilation amplitudes and factorization in B to phi Kstar
9 pages, 1 table
Eur.Phys.J.C29:207-213,2003
10.1140/epjc/s2003-01217-2
null
hep-ph
null
We study the decay $B^\pm\to \phi K^{\ast\pm}$, followed by the decay of the outgoing vector mesons into two pseudoscalars. The analysis of angular distributions of the decay products is shown to provide useful information about the annihilation contributions and possible tests of factorization.
[ { "created": "Mon, 7 Apr 2003 14:58:19 GMT", "version": "v1" } ]
2009-01-07
[ [ "Epele", "L. N.", "" ], [ "Dumm", "D. Gomez", "" ], [ "Szynkman", "A.", "" ] ]
We study the decay $B^\pm\to \phi K^{\ast\pm}$, followed by the decay of the outgoing vector mesons into two pseudoscalars. The analysis of angular distributions of the decay products is shown to provide useful information about the annihilation contributions and possible tests of factorization.
1807.01571
Andreas Papaefstathiou
Karl Nordstr\"om and Andreas Papaefstathiou
$VHH$ production at the High-Luminosity LHC
14 pages, 8 figures, 4 tables
null
null
Nikhef 2018-028
hep-ph hep-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the phenomenology of associated production of a vector boson with a pair of Higgs bosons ($VHH$) at the High-Luminosity LHC. Despite the low rate of this channel, the scaling of the cross section suggests a measurement could be a useful probe of modifications of the trilinear Higgs boson coupling and anomalous interactions in the gauge-Higgs sector. We focus on both $WHH$ and $ZHH$ production, using the leptonic ($W \to l \nu$, $Z \to ll$, $Z \to \nu \nu$) decay modes of the vector bosons and the $HH \to 4b$ di-Higgs decay mode. We show that top pair backgrounds are problematic for the $W \to l \nu$ and $Z \to \nu \nu$ channels, leaving $Z \to ll$ as the most promising decay mode. However, even for this channel, we find limited sensitivity due to a low signal rate. We discuss some potential avenues for improvement.
[ { "created": "Wed, 4 Jul 2018 13:39:01 GMT", "version": "v1" } ]
2018-07-05
[ [ "Nordström", "Karl", "" ], [ "Papaefstathiou", "Andreas", "" ] ]
We study the phenomenology of associated production of a vector boson with a pair of Higgs bosons ($VHH$) at the High-Luminosity LHC. Despite the low rate of this channel, the scaling of the cross section suggests a measurement could be a useful probe of modifications of the trilinear Higgs boson coupling and anomalous interactions in the gauge-Higgs sector. We focus on both $WHH$ and $ZHH$ production, using the leptonic ($W \to l \nu$, $Z \to ll$, $Z \to \nu \nu$) decay modes of the vector bosons and the $HH \to 4b$ di-Higgs decay mode. We show that top pair backgrounds are problematic for the $W \to l \nu$ and $Z \to \nu \nu$ channels, leaving $Z \to ll$ as the most promising decay mode. However, even for this channel, we find limited sensitivity due to a low signal rate. We discuss some potential avenues for improvement.
hep-ph/0208123
Vladimir Anisovich
V.V. Anisovich
Systematics of quark-antiquark states and scalar exotic mesons
55 pages, LaTeX, 11 figures, epsfig.sty, Corrections are done in line with published version
Phys.Usp.47:45-67,2004; Usp.Fiz.Nauk 47:49-72,2004
10.1070/PU2004v047n01ABEH001333
null
hep-ph
null
The analysis of the experimental data of Crystal Barrel Collaboration on the p anti-p annihilation in flight with the production of mesons in the final state resulted in a discovery of a large number of mesons over the region 1900-2400 MeV, thus allowing us to systematize quark-antiquark states in the (n,M^2) and (J,M^2) planes, where n and J are radial quantum number and spin of the meson with the mass M. The data point to meson trajectories in these planes being approximately linear, with a universal slope. The sector of scalar mesons is discussed in more detail, where, on the basis of the recent K-matrix analysis, the nonet classification of quark-antiquark states was performed: in the region below 2000 MeV, two scalar nonets are fixed, that is, the basic one and the nonet of the first radial excitation. In the scalar sector, there are two states with the isospin I=0, which are extra ones with respect to the quark--antiquark classification, i.e. exotic states: the broad resonance f0(1200-1600) and the light sigma-meson. The ratios of coupling constants for hadronic decays to the states pi pi, K anti-K, eta eta, eta eta' point to the gluonium nature of the broad state f0(1200-1600).
[ { "created": "Tue, 13 Aug 2002 10:23:48 GMT", "version": "v1" }, { "created": "Fri, 14 Mar 2003 11:40:32 GMT", "version": "v2" }, { "created": "Mon, 26 Jan 2004 08:03:16 GMT", "version": "v3" } ]
2009-11-07
[ [ "Anisovich", "V. V.", "" ] ]
The analysis of the experimental data of Crystal Barrel Collaboration on the p anti-p annihilation in flight with the production of mesons in the final state resulted in a discovery of a large number of mesons over the region 1900-2400 MeV, thus allowing us to systematize quark-antiquark states in the (n,M^2) and (J,M^2) planes, where n and J are radial quantum number and spin of the meson with the mass M. The data point to meson trajectories in these planes being approximately linear, with a universal slope. The sector of scalar mesons is discussed in more detail, where, on the basis of the recent K-matrix analysis, the nonet classification of quark-antiquark states was performed: in the region below 2000 MeV, two scalar nonets are fixed, that is, the basic one and the nonet of the first radial excitation. In the scalar sector, there are two states with the isospin I=0, which are extra ones with respect to the quark--antiquark classification, i.e. exotic states: the broad resonance f0(1200-1600) and the light sigma-meson. The ratios of coupling constants for hadronic decays to the states pi pi, K anti-K, eta eta, eta eta' point to the gluonium nature of the broad state f0(1200-1600).
hep-ph/9809442
Jianwei Qiu
Jianwei Qiu (Iowa State/BNL), James P. Vary (Iowa State) and Xiaofei Zhang (Iowa State)
J/\psi Suppression in Nucleus-Nucleus Collisions
Revtex 10 pages and 2 postscript figures
Phys.Rev.Lett. 88 (2002) 232301
10.1103/PhysRevLett.88.232301
null
hep-ph nucl-th
null
We propose a model for the production and suppression of J/\psi mesons in high-energy hadronic collisions. We factorized the process into a production of the $c\bar{c}$ pairs of relative momentum $k=k_c-k_{\bar{c}}$ convoluted with a transition probability from the produced $c\bar{c}$ pairs into the observed J/$\psi$ mesons. As the produced $c\bar{c}$ pairs exit the nuclear matter, the multiple scattering between the colored $c$ and $\bar{c}$ and the nuclear medium increases the square of the relative momentum between the $c$ and $\bar{c}, q^2=-k^2$, such that some of the $c\bar{c}$ pairs gain enough invariant mass to transmute into open charm states. With only one parameter, the amount of energy gained by the produced $c\bar{c}$ pair per unit length in the nuclear medium, our model can fit all observed J/\psi suppression data including recent NA50 data from Pb-Pb collisions.
[ { "created": "Fri, 18 Sep 1998 00:07:07 GMT", "version": "v1" } ]
2009-10-31
[ [ "Qiu", "Jianwei", "", "Iowa State/BNL" ], [ "Vary", "James P.", "", "Iowa State" ], [ "Zhang", "Xiaofei", "", "Iowa State" ] ]
We propose a model for the production and suppression of J/\psi mesons in high-energy hadronic collisions. We factorized the process into a production of the $c\bar{c}$ pairs of relative momentum $k=k_c-k_{\bar{c}}$ convoluted with a transition probability from the produced $c\bar{c}$ pairs into the observed J/$\psi$ mesons. As the produced $c\bar{c}$ pairs exit the nuclear matter, the multiple scattering between the colored $c$ and $\bar{c}$ and the nuclear medium increases the square of the relative momentum between the $c$ and $\bar{c}, q^2=-k^2$, such that some of the $c\bar{c}$ pairs gain enough invariant mass to transmute into open charm states. With only one parameter, the amount of energy gained by the produced $c\bar{c}$ pair per unit length in the nuclear medium, our model can fit all observed J/\psi suppression data including recent NA50 data from Pb-Pb collisions.
hep-ph/9205246
null
Gary R. Goldstein, K. Sliwa, and R.H. Dalitz
On Observing Top Quark Production at the Tevatron
8 pages, TUFTS-TH-92-G01 (Two minor TeX mistakes corrected)
Phys.Rev.D47:967-972,1993
10.1103/PhysRevD.47.967
null
hep-ph
null
A technique for separating top quark production from Standard Model background events is introduced. It is applicable to the channel in which one top quark decays semi-leptonically and its anti-quark decays hadronically into three jets, or vice versa. The method is shown to discriminate dramatically between Monte Carlo generated events with and without simulated top quarks of mass around 120 GeV and above. The simulations were performed with CDF detector characteristics incorporated, showing that the method is applicable to existing data.
[ { "created": "Sat, 30 May 1992 02:54:00 GMT", "version": "v1" }, { "created": "Sat, 30 May 1992 20:59:00 GMT", "version": "v2" } ]
2010-11-01
[ [ "Goldstein", "Gary R.", "" ], [ "Sliwa", "K.", "" ], [ "Dalitz", "R. H.", "" ] ]
A technique for separating top quark production from Standard Model background events is introduced. It is applicable to the channel in which one top quark decays semi-leptonically and its anti-quark decays hadronically into three jets, or vice versa. The method is shown to discriminate dramatically between Monte Carlo generated events with and without simulated top quarks of mass around 120 GeV and above. The simulations were performed with CDF detector characteristics incorporated, showing that the method is applicable to existing data.
0905.3489
Guillermo R\'ios M\'arquez
Guillermo R\'ios, \'Angel G\'omez Nicola, Christoph Hanhart, Jos\'e Ram\'on Pel\'aez
Chiral Extrapolations of light resonances from dispersion relations and Chiral Perturbation Theory
7 pages, 4 figures, to appear in the proceedings of the "International Workshop on Effective Field Theories: from the Pion to the Upsilon. EFT09", Valencia, 1 -6 Feb. 2009
null
null
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We review our recent study of the pion mass dependence of the rho and sigma resonances generated from one-loop SU(2) Chiral Perturbation Theory (ChPT) with the Inverse Amplitude Method (IAM) which was modified to properly account for the Adler zero. The method is based on analyticity, elastic unitarity and ChPT at low energies, thus yielding the pion mass dependence of the resonance pole positions from the ChPT series up to a given order. We find that the rho-pi-pi coupling constant is almost m_pi independent and that our prediction compare well with some recent lattice results for the rho mass. These findings may be relevant for studies of the meson spectrum and form factors on the lattice.
[ { "created": "Thu, 21 May 2009 13:41:52 GMT", "version": "v1" } ]
2009-05-22
[ [ "Ríos", "Guillermo", "" ], [ "Nicola", "Ángel Gómez", "" ], [ "Hanhart", "Christoph", "" ], [ "Peláez", "José Ramón", "" ] ]
We review our recent study of the pion mass dependence of the rho and sigma resonances generated from one-loop SU(2) Chiral Perturbation Theory (ChPT) with the Inverse Amplitude Method (IAM) which was modified to properly account for the Adler zero. The method is based on analyticity, elastic unitarity and ChPT at low energies, thus yielding the pion mass dependence of the resonance pole positions from the ChPT series up to a given order. We find that the rho-pi-pi coupling constant is almost m_pi independent and that our prediction compare well with some recent lattice results for the rho mass. These findings may be relevant for studies of the meson spectrum and form factors on the lattice.
1902.07185
Peter Denton
Peter B. Denton and Stephen J. Parke
Simple and Precise Factorization of the Jarlskog Invariant for Neutrino Oscillations in Matter
7 pages, 3 figures; new results added, matches published version
Phys. Rev. D 100, 053004 (2019)
10.1103/PhysRevD.100.053004
FERMILAB-PUB-19-072-T
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
For neutrino propagation in matter, we show that the Jarlskog invariant, which controls the size of true CP violation in neutrino oscillation appearance experiments, factorizes into three pieces: the vacuum Jarlskog invariant times two simple two-flavor matter resonance factors that control the matter effects for the solar and atmospheric resonances independently. If the solar effective matter potential and the atmospheric effective $\Delta m^2$ are chosen carefully for these two resonance factors, then the fractional corrections to this factorization are an impressive 0.04\% or smaller. We also show that the inverse of the square of the Jarlskog in matter ($1/\hat{J}^2$) is a fourth order polynomial in the matter potential which guarantees that it can be factored into two quadratics which immediately implies the functional form of our approximate, factorized expression.
[ { "created": "Tue, 19 Feb 2019 18:35:13 GMT", "version": "v1" }, { "created": "Wed, 12 Jun 2019 16:18:29 GMT", "version": "v2" }, { "created": "Wed, 11 Sep 2019 21:51:36 GMT", "version": "v3" } ]
2019-09-18
[ [ "Denton", "Peter B.", "" ], [ "Parke", "Stephen J.", "" ] ]
For neutrino propagation in matter, we show that the Jarlskog invariant, which controls the size of true CP violation in neutrino oscillation appearance experiments, factorizes into three pieces: the vacuum Jarlskog invariant times two simple two-flavor matter resonance factors that control the matter effects for the solar and atmospheric resonances independently. If the solar effective matter potential and the atmospheric effective $\Delta m^2$ are chosen carefully for these two resonance factors, then the fractional corrections to this factorization are an impressive 0.04\% or smaller. We also show that the inverse of the square of the Jarlskog in matter ($1/\hat{J}^2$) is a fourth order polynomial in the matter potential which guarantees that it can be factored into two quadratics which immediately implies the functional form of our approximate, factorized expression.
hep-ph/0305302
Witold Skiba
Witold Skiba and John Terning
A Simple Model of two Little Higgses
14 pages; changed the normalization of f to ease comparison, fixed a bug in the fitting program which weakened the bound on f, extended discussion in section 3
Phys.Rev.D68:075001,2003
10.1103/PhysRevD.68.075001
null
hep-ph
null
We construct a little Higgs model using a simple global symmetry group SU(9) spontaneously broken to SU(8). The electroweak interactions are extended to SU(3)xU(1) and embedded in SU(9). At the electroweak scale, our model is a two Higgs-doublet model. At the TeV scale, there are additional states, which are responsible for the cancellation of one loop quadratic divergences. We compute the effects of heavy states on the precision electroweak observables and find that the lower bounds on the masses of heavy gauge bosons and fermions are between 1 and 2 TeV.
[ { "created": "Tue, 27 May 2003 21:41:02 GMT", "version": "v1" }, { "created": "Thu, 24 Jul 2003 17:16:28 GMT", "version": "v2" } ]
2010-04-06
[ [ "Skiba", "Witold", "" ], [ "Terning", "John", "" ] ]
We construct a little Higgs model using a simple global symmetry group SU(9) spontaneously broken to SU(8). The electroweak interactions are extended to SU(3)xU(1) and embedded in SU(9). At the electroweak scale, our model is a two Higgs-doublet model. At the TeV scale, there are additional states, which are responsible for the cancellation of one loop quadratic divergences. We compute the effects of heavy states on the precision electroweak observables and find that the lower bounds on the masses of heavy gauge bosons and fermions are between 1 and 2 TeV.
hep-ph/0407120
Eric S. Swanson
T. Barnes, F.E. Close, J.J. Dudek, S. Godfrey, E.S. Swanson
Options for the SELEX state D$_{s\J}^+(2632)$
6 revtex4 pages, 2 eps figures
Phys.Lett.B600:223-230,2004
10.1016/j.physletb.2004.08.075
null
hep-ph hep-ex
null
We consider possible assignments for the D$_{s\J}^+(2632)$, which was recently reported in D$_s^+\eta$ and D$^0$K$^+$ final states by the SELEX Collaboration at Fermilab. The most plausible quark model assignment for this state is the first radial excitation ($2^3\S_1$) of the $c\bar s$ D$_s^*(2112)$, although the predicted mass and strong decay branching fractions for this assignment are not in agreement with the SELEX data. The reported dominance of D$_s\eta$ over DK appears especially problematic. An intriguing similarity to the K$^*(1414)$ is noted. $2^3\S_1$--$^3\D_1$ configuration mixing is also considered, and we find that this effect is unlikely to resolve the branching fraction discrepancy. Other interpretations as a $c\bar s$-hybrid or a two-meson molecule are also considered, but appear unlikely. Thus, if this state is confirmed, it will require reconsideration of the systematics of charmed meson spectroscopy and strong decays.
[ { "created": "Sun, 11 Jul 2004 19:25:48 GMT", "version": "v1" } ]
2008-11-26
[ [ "Barnes", "T.", "" ], [ "Close", "F. E.", "" ], [ "Dudek", "J. J.", "" ], [ "Godfrey", "S.", "" ], [ "Swanson", "E. S.", "" ] ]
We consider possible assignments for the D$_{s\J}^+(2632)$, which was recently reported in D$_s^+\eta$ and D$^0$K$^+$ final states by the SELEX Collaboration at Fermilab. The most plausible quark model assignment for this state is the first radial excitation ($2^3\S_1$) of the $c\bar s$ D$_s^*(2112)$, although the predicted mass and strong decay branching fractions for this assignment are not in agreement with the SELEX data. The reported dominance of D$_s\eta$ over DK appears especially problematic. An intriguing similarity to the K$^*(1414)$ is noted. $2^3\S_1$--$^3\D_1$ configuration mixing is also considered, and we find that this effect is unlikely to resolve the branching fraction discrepancy. Other interpretations as a $c\bar s$-hybrid or a two-meson molecule are also considered, but appear unlikely. Thus, if this state is confirmed, it will require reconsideration of the systematics of charmed meson spectroscopy and strong decays.
hep-ph/9508395
Theodore Tomaras
C. Bachas and T. N. Tomaras
Membranes in the two-Higgs standard model
7 pages, latex, 3 figures available upon request
Phys.Rev.Lett. 76 (1996) 356-359
10.1103/PhysRevLett.76.356
CPTh-S369.0895, Crete-95-16
hep-ph hep-th
null
We present some non-topological static wall solutions in two-Higgs extensions of the standard model. They are classically stable in a large region of parameter space, compatible with perturbative unitarity and with present phenomenological bounds.
[ { "created": "Tue, 29 Aug 1995 18:31:40 GMT", "version": "v1" } ]
2009-10-28
[ [ "Bachas", "C.", "" ], [ "Tomaras", "T. N.", "" ] ]
We present some non-topological static wall solutions in two-Higgs extensions of the standard model. They are classically stable in a large region of parameter space, compatible with perturbative unitarity and with present phenomenological bounds.
hep-ph/0211455
Piotr Niezurawski
P. Niezurawski, A. F. Zarnecki, M. Krawczyk
The SM Higgs-boson production in gamma gamma -> h -> bb at the Photon Collider at TESLA
Presented at the International Workshop on Linear Colliders LCWS(2002), Jeju, Korea
null
null
null
hep-ph
null
Measuring the Gamma(h -> gamma gamma)Br(h -> bb) decay at the photon collider at TESLA is studied for a Standard Model Higgs boson of mass m_h = 120 GeV. The main background due to the process gamma gamma -> QQ(g), where Q = b,c, is estimated using the NLO QCD program (G. Jikia); the results obtained are compared with the LO estimate. Using a realistic luminosity spectrum and performing a detector simulation, we find that Gamma(h -> gamma gamma)Br(h -> bb) can be measured with an accuracy better than 2% after one year of photon collider running.
[ { "created": "Fri, 29 Nov 2002 10:36:48 GMT", "version": "v1" } ]
2007-05-23
[ [ "Niezurawski", "P.", "" ], [ "Zarnecki", "A. F.", "" ], [ "Krawczyk", "M.", "" ] ]
Measuring the Gamma(h -> gamma gamma)Br(h -> bb) decay at the photon collider at TESLA is studied for a Standard Model Higgs boson of mass m_h = 120 GeV. The main background due to the process gamma gamma -> QQ(g), where Q = b,c, is estimated using the NLO QCD program (G. Jikia); the results obtained are compared with the LO estimate. Using a realistic luminosity spectrum and performing a detector simulation, we find that Gamma(h -> gamma gamma)Br(h -> bb) can be measured with an accuracy better than 2% after one year of photon collider running.
2110.12086
Ismail Zahed
Thors Hans Hansson and Ismail Zahed
QCD Sum Rules at High Temperature
This paper was posted on the SLAC server on June 5, 1990
null
null
null
hep-ph hep-lat hep-th nucl-th
http://creativecommons.org/licenses/by/4.0/
We generalize the sum rule approach to investigate the nonperturbative structure of QCD at high temperature. Salient features of the QCD phase above $T_c$ are discussed, and included in the form of power corrections or condensate insertions, in an operator product expansion of gauge invariant correlators. It is shown that for a plausible choice of condensates, QCD at high temperature exhibits color singlet excitations in the vector channels, as opposed to merely screened quarks and gluons.
[ { "created": "Fri, 22 Oct 2021 22:35:53 GMT", "version": "v1" } ]
2021-10-26
[ [ "Hansson", "Thors Hans", "" ], [ "Zahed", "Ismail", "" ] ]
We generalize the sum rule approach to investigate the nonperturbative structure of QCD at high temperature. Salient features of the QCD phase above $T_c$ are discussed, and included in the form of power corrections or condensate insertions, in an operator product expansion of gauge invariant correlators. It is shown that for a plausible choice of condensates, QCD at high temperature exhibits color singlet excitations in the vector channels, as opposed to merely screened quarks and gluons.
hep-ph/0701202
Michael Klasen
G. Bozzi (ITP Karlsruhe), B. Fuks, M. Klasen (LPSC Grenoble)
Threshold Resummation for Slepton-Pair Production at Hadron Colliders
20 pages, 11 figures. Wording of several paragraphs improved, some typos corrected, version accepted by Nucl. Phys. B
Nucl.Phys.B777:157-181,2007
10.1016/j.nuclphysb.2007.03.052
KA-TP-02-2007, LPSC 07-002
hep-ph
null
We present a first and extensive study of threshold resummation effects for supersymmetric (SUSY) particle production at hadron colliders, focusing on Drell-Yan like slepton-pair and slepton-sneutrino associated production. After confirming the known next-to-leading order (NLO) QCD corrections and generalizing the NLO SUSY-QCD corrections to the case of mixing squarks in the virtual loop contributions, we employ the usual Mellin N-space resummation formalism with the minimal prescription for the inverse Mellin-transform and improve it by resumming 1/N-suppressed and a class of N-independent universal contributions. Numerically, our results increase the theoretical cross sections by 5 to 15% with respect to the NLO predictions and stabilize them by reducing the scale dependence from up to 20% at NLO to less than 10% with threshold resummation.
[ { "created": "Wed, 24 Jan 2007 07:37:52 GMT", "version": "v1" }, { "created": "Tue, 10 Apr 2007 11:32:32 GMT", "version": "v2" }, { "created": "Fri, 1 Jun 2007 12:25:13 GMT", "version": "v3" } ]
2008-11-26
[ [ "Bozzi", "G.", "", "ITP Karlsruhe" ], [ "Fuks", "B.", "", "LPSC Grenoble" ], [ "Klasen", "M.", "", "LPSC Grenoble" ] ]
We present a first and extensive study of threshold resummation effects for supersymmetric (SUSY) particle production at hadron colliders, focusing on Drell-Yan like slepton-pair and slepton-sneutrino associated production. After confirming the known next-to-leading order (NLO) QCD corrections and generalizing the NLO SUSY-QCD corrections to the case of mixing squarks in the virtual loop contributions, we employ the usual Mellin N-space resummation formalism with the minimal prescription for the inverse Mellin-transform and improve it by resumming 1/N-suppressed and a class of N-independent universal contributions. Numerically, our results increase the theoretical cross sections by 5 to 15% with respect to the NLO predictions and stabilize them by reducing the scale dependence from up to 20% at NLO to less than 10% with threshold resummation.
0905.4416
Claudio Coriano
Claudio Coriano, Marco Guzzi, Antonio Mariano
Searching for an Axion-like Particle at the Large Hadron Collider
4 pages 1 Fig. Presented at IFAE 2009, Bari, 15-17 April 2009, Italy
Nuovo Cim.C32N3-4::265-267,2009
10.1393/ncc/i2009-10434-4
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Axion-like particles are an important part of the spectrum of anomalous gauge theories involving modified mechanisms of cancellation of the gauge anomalies. Among these are intersecting brane models, which are characterized by the presence of one physical axion. We overview a recent study of their supersymmetric construction and some LHC studies of the productions rates for a gauged axion.
[ { "created": "Wed, 27 May 2009 13:39:40 GMT", "version": "v1" } ]
2014-11-20
[ [ "Coriano", "Claudio", "" ], [ "Guzzi", "Marco", "" ], [ "Mariano", "Antonio", "" ] ]
Axion-like particles are an important part of the spectrum of anomalous gauge theories involving modified mechanisms of cancellation of the gauge anomalies. Among these are intersecting brane models, which are characterized by the presence of one physical axion. We overview a recent study of their supersymmetric construction and some LHC studies of the productions rates for a gauged axion.
hep-ph/0411193
Borut Bajc
Borut Bajc and Goran Senjanovic
Radiative seesaw: a case for split supersymmetry
12 pages, 2 figures, a few references and short comment on gluinos added
Phys.Lett. B610 (2005) 80-86
10.1016/j.physletb.2005.01.074
null
hep-ph
null
We revive Witten's mechanism for the radiative seesaw induced neutrino masses in SO(10) grand unified theory. We propose its extension to charged fermion masses as a possible cure for wrong tree level mass relations. We offer two simple realizations that can produce a realistic fermionic spectrum. The first one requires two 10 dimensional Higgses in the Yukawa sector and utilizes radiative effects for charged fermion masses. The second one trades one 10 for a 120 dimensional Higgs and leads to the SO(10) theory with less parameters in the Yukawa sector. The mechanism works only if supersymmetry is broken at the GUT scale while gauginos and higgsinos remain at TeV. This provides a strong rationale for the so called split supersymmetry.
[ { "created": "Mon, 15 Nov 2004 17:58:45 GMT", "version": "v1" }, { "created": "Tue, 30 Nov 2004 13:14:37 GMT", "version": "v2" } ]
2009-11-10
[ [ "Bajc", "Borut", "" ], [ "Senjanovic", "Goran", "" ] ]
We revive Witten's mechanism for the radiative seesaw induced neutrino masses in SO(10) grand unified theory. We propose its extension to charged fermion masses as a possible cure for wrong tree level mass relations. We offer two simple realizations that can produce a realistic fermionic spectrum. The first one requires two 10 dimensional Higgses in the Yukawa sector and utilizes radiative effects for charged fermion masses. The second one trades one 10 for a 120 dimensional Higgs and leads to the SO(10) theory with less parameters in the Yukawa sector. The mechanism works only if supersymmetry is broken at the GUT scale while gauginos and higgsinos remain at TeV. This provides a strong rationale for the so called split supersymmetry.
hep-ph/9308274
Andrey Kataev
D.J.Broadhurst and A.L.Kataev
Connections between Deep-Inelastic and Annihilation Processes at Next-to-Next-to-Leading Order and Beyond
11 pages, LATEX, preprint INR-820/93, OUT-4102-45; In memoriam Sergei Grogorievich Corishny, 1958-1988
Phys.Lett. B315 (1993) 179-187
10.1016/0370-2693(93)90177-J
null
hep-ph
null
We have discovered 7 intimate connections between the published results for the radiative corrections, $\Ck$, to the Gross--Llewellyn Smith (GLS) sum rule, in deep-inelastic lepton scattering, and the radiative corrections, $\Cr$, to the Adler function of the flavour-singlet vector current, in $\ee$ annihilation. These include a surprising relation between the scheme-independent single-electron-loop contributions to the 4-loop QED $\beta$\/-function and the zero-fermion-loop abelian terms in the 3-loop GLS sum rule. The combined effect of all 7 relations is to give the factorization of the 2-loop $\beta$\/-function in \[\Ds\equiv\Ck\Cr-1=\frac{\Be}{\Aq}\left\{S_1\Cf\Aq+\left[S_2\Tf\Nf +\Sa\Ca+\Sf\Cf\right]\Cf\Aq^2\right\}+O(\Aq^4)\,,\] where $\Aq=\al(\mu^2=Q^2)/4\pi$ is the $\MS$ coupling of an arbitrary colour gauge theory, and \[S_1=-\Df{21}{2}+12\Ze3\,;\quad S_2=\Df{326}{3}-\Df{304}{3}\Ze3\,;\quad \Sa=-\Df{629}{2}+\Df{884}{3}\Ze3\,;\quad \Sf=\Df{397}{6}+136\Ze3-240\Ze5\] specify the sole content of $\Ck$ that is not already encoded in $\Cr$ and $\Be=Q^2\rd\Aq/\rd Q^2$ at $O(\Aq^3)$. The same result is obtained by combining the radiative corrections to Bjorken's polarized sum rule with those for the Adler function of the non-singlet axial current. We suggest possible origins of $\beta$ in the `Crewther discrepancy', $\Ds$, and determine $\Ds/(\Be/\Aq)$, to all orders in $\Nf\Aq$, in the large-$\Nf$ limit, obtaining the {\em entire\/} series of coefficients of which $S_1$ and $S_2$ are merely the first two members.
[ { "created": "Fri, 13 Aug 1993 16:06:15 GMT", "version": "v1" } ]
2009-10-22
[ [ "Broadhurst", "D. J.", "" ], [ "Kataev", "A. L.", "" ] ]
We have discovered 7 intimate connections between the published results for the radiative corrections, $\Ck$, to the Gross--Llewellyn Smith (GLS) sum rule, in deep-inelastic lepton scattering, and the radiative corrections, $\Cr$, to the Adler function of the flavour-singlet vector current, in $\ee$ annihilation. These include a surprising relation between the scheme-independent single-electron-loop contributions to the 4-loop QED $\beta$\/-function and the zero-fermion-loop abelian terms in the 3-loop GLS sum rule. The combined effect of all 7 relations is to give the factorization of the 2-loop $\beta$\/-function in \[\Ds\equiv\Ck\Cr-1=\frac{\Be}{\Aq}\left\{S_1\Cf\Aq+\left[S_2\Tf\Nf +\Sa\Ca+\Sf\Cf\right]\Cf\Aq^2\right\}+O(\Aq^4)\,,\] where $\Aq=\al(\mu^2=Q^2)/4\pi$ is the $\MS$ coupling of an arbitrary colour gauge theory, and \[S_1=-\Df{21}{2}+12\Ze3\,;\quad S_2=\Df{326}{3}-\Df{304}{3}\Ze3\,;\quad \Sa=-\Df{629}{2}+\Df{884}{3}\Ze3\,;\quad \Sf=\Df{397}{6}+136\Ze3-240\Ze5\] specify the sole content of $\Ck$ that is not already encoded in $\Cr$ and $\Be=Q^2\rd\Aq/\rd Q^2$ at $O(\Aq^3)$. The same result is obtained by combining the radiative corrections to Bjorken's polarized sum rule with those for the Adler function of the non-singlet axial current. We suggest possible origins of $\beta$ in the `Crewther discrepancy', $\Ds$, and determine $\Ds/(\Be/\Aq)$, to all orders in $\Nf\Aq$, in the large-$\Nf$ limit, obtaining the {\em entire\/} series of coefficients of which $S_1$ and $S_2$ are merely the first two members.
hep-ph/0404107
Kenneth Lane
Adam Martin and Kenneth Lane
CP Violation and Flavor Mixing in Technicolor Theories
44 pages, Latex, with 14 postscript figures. Version that will appear in Physical Review D. Error in Delta M_B corrected, leading to increased lower bounds on Z' and coloron masses and modest changes in calculated sin(2 beta). A small error in Re(epsilon'/epsilon) was also corrected
Phys.Rev. D71 (2005) 015011
10.1103/PhysRevD.71.015011
BUHEP-04-03
hep-ph hep-ex
null
Vacuum alignment in technicolor models provides an attractive origin for the quarks' CP violation and, possibly, a natural solution for the strong-CP problem of QCD. We discuss these topics in this paper. Then we apply them to determine plausible mixing matrices for left and right-handed quarks. These matrices determine the Cabibbo-Kobayashi-Maskawa matrix as well as new mixing angles and phases that are observable in extended technicolor (ETC) and topcolor (TC2) interactions. We determine the contributions of these new interactions to CP-violating and mixing observables in the K^0, B_d and B_s systems. Consistency with mixing and CP violation in the K^0 system requires assuming that ETC interactions are electroweak generation conserving even if technicolor has a walking gauge coupling. Large ETC gauge boson masses and small intergenerational mixing then result in negligibly small ETC contributions to B-meson mixing and CP violation and to Re(epsilon'/epsilon). We confirm our earlier strong lower bounds on TC2 gauge boson masses from B_d--B_d-bar mixing. We then pay special attention to the possibility that current experiments indicate a deviation from standard model expectations of the values of sin(2 beta) measured in B_d -> J/psi K_S, phi K_S, eta' K_S, and pi K_S, studying the ability of TC2 to account for these. We also determine the TC2 contribution to Delta M_{B_s} and to Re(epsilon'/epsilon), and find them to be appreciable.
[ { "created": "Tue, 13 Apr 2004 18:51:54 GMT", "version": "v1" }, { "created": "Tue, 7 Dec 2004 21:39:14 GMT", "version": "v2" } ]
2009-11-10
[ [ "Martin", "Adam", "" ], [ "Lane", "Kenneth", "" ] ]
Vacuum alignment in technicolor models provides an attractive origin for the quarks' CP violation and, possibly, a natural solution for the strong-CP problem of QCD. We discuss these topics in this paper. Then we apply them to determine plausible mixing matrices for left and right-handed quarks. These matrices determine the Cabibbo-Kobayashi-Maskawa matrix as well as new mixing angles and phases that are observable in extended technicolor (ETC) and topcolor (TC2) interactions. We determine the contributions of these new interactions to CP-violating and mixing observables in the K^0, B_d and B_s systems. Consistency with mixing and CP violation in the K^0 system requires assuming that ETC interactions are electroweak generation conserving even if technicolor has a walking gauge coupling. Large ETC gauge boson masses and small intergenerational mixing then result in negligibly small ETC contributions to B-meson mixing and CP violation and to Re(epsilon'/epsilon). We confirm our earlier strong lower bounds on TC2 gauge boson masses from B_d--B_d-bar mixing. We then pay special attention to the possibility that current experiments indicate a deviation from standard model expectations of the values of sin(2 beta) measured in B_d -> J/psi K_S, phi K_S, eta' K_S, and pi K_S, studying the ability of TC2 to account for these. We also determine the TC2 contribution to Delta M_{B_s} and to Re(epsilon'/epsilon), and find them to be appreciable.
hep-ph/0510399
J. A. R. Cembranos
J. A. R. Cembranos, A. Dobado and A. L. Maroto
Branon radiative corrections to collider physics and precision observables
23 pages, 4 figures, LaTeX
Phys.Rev.D73:035008,2006
10.1103/PhysRevD.73.035008
UCI-TR-2005-37
hep-ph
null
In the context of brane-world scenarios, we study the effects produced by the exchange of virtual massive branons. A one-loop calculation is performed which generates higher-dimensional operators involving SM fields suppressed by powers of the brane tension scale. We discuss constraints on this scenario from colliders such as HERA, LEP and Tevatron and prospects for future detections at LHC or ILC. The most interesting phenomenology comes from new four-particles vertices induced by branon radiative corrections, mainly from four fermion interactions. The presence of flexible branes modifies also the muon anomalous magnetic moment and the electroweak precision observables.
[ { "created": "Sun, 30 Oct 2005 01:24:12 GMT", "version": "v1" } ]
2008-11-26
[ [ "Cembranos", "J. A. R.", "" ], [ "Dobado", "A.", "" ], [ "Maroto", "A. L.", "" ] ]
In the context of brane-world scenarios, we study the effects produced by the exchange of virtual massive branons. A one-loop calculation is performed which generates higher-dimensional operators involving SM fields suppressed by powers of the brane tension scale. We discuss constraints on this scenario from colliders such as HERA, LEP and Tevatron and prospects for future detections at LHC or ILC. The most interesting phenomenology comes from new four-particles vertices induced by branon radiative corrections, mainly from four fermion interactions. The presence of flexible branes modifies also the muon anomalous magnetic moment and the electroweak precision observables.
1102.5753
Satoshi Nakamura
Satoshi X. Nakamura (Jefferson Lab)
Effect of three-pion unitarity on resonance poles from heavy meson decays
4 pages, 4 figures, Contribution to the proceedings of International conference on the structure of baryons (BARYONS'10), Osaka, Japan, Dec. 7-11, 2010
null
10.1063/1.3647399
null
hep-ph hep-ex nucl-ex nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the final state interaction in 3-pion decay of meson resonances at the Excited Baryon Analysis Center (EBAC) of JLab. We apply the dynamical coupled-channels formulation which has been extensively used by EBAC to extract N* information. The formulation satisfies the 3-pion unitarity condition which has been missed in the existing works with the isobar models. We report the effect of the 3-pion unitarity on the meson resonance pole positions and Dalitz plot.
[ { "created": "Mon, 28 Feb 2011 19:39:01 GMT", "version": "v1" } ]
2015-05-27
[ [ "Nakamura", "Satoshi X.", "", "Jefferson Lab" ] ]
We study the final state interaction in 3-pion decay of meson resonances at the Excited Baryon Analysis Center (EBAC) of JLab. We apply the dynamical coupled-channels formulation which has been extensively used by EBAC to extract N* information. The formulation satisfies the 3-pion unitarity condition which has been missed in the existing works with the isobar models. We report the effect of the 3-pion unitarity on the meson resonance pole positions and Dalitz plot.
hep-ph/9801297
U. Meissner
V\'eronique Bernard, Harold W. Fearing, Thomas R. Hemmert, Ulf-G. Mei{\ss}ner
The form factors of the nucleon at small momentum transfer
21 pp, RevTeX, uses epsf, 4 figs, minor corrections, accepted for publication in Nucl.Phys.A
Nucl.Phys. A635 (1998) 121-145; Erratum-ibid. A642 (1998) 563-563
10.1016/S0375-9474(98)00175-4
KFA-IKP(TH)-1998-01, LPT-98-01, TRI-PP-97-73
hep-ph nucl-th
null
We study the low energy expansion of the nucleon's electroweak form factors in the framework of an effective chiral Lagrangian including pions, nucleons and the $Delta (1232)$. We work to third order in the so-called small scale expansion and compare the results with the ones previously obtained in the chiral expansion. In addition, these calculations serve as a first exploratory study of renormalization and decoupling within the small scale expansion.
[ { "created": "Wed, 14 Jan 1998 12:11:08 GMT", "version": "v1" }, { "created": "Tue, 28 Apr 1998 15:16:40 GMT", "version": "v2" } ]
2009-10-31
[ [ "Bernard", "Véronique", "" ], [ "Fearing", "Harold W.", "" ], [ "Hemmert", "Thomas R.", "" ], [ "Meißner", "Ulf-G.", "" ] ]
We study the low energy expansion of the nucleon's electroweak form factors in the framework of an effective chiral Lagrangian including pions, nucleons and the $Delta (1232)$. We work to third order in the so-called small scale expansion and compare the results with the ones previously obtained in the chiral expansion. In addition, these calculations serve as a first exploratory study of renormalization and decoupling within the small scale expansion.
1901.11473
Alexei Smirnov Yu
A Y Smirnov
The Mikheyev-Smirnov-Wolfenstein (MSW) Effect
Talk given at the International conference on History of the Neutrino, September 5 - 7, 2018, Paris, France. LaTeX, 17 pages, 7 figures. Typos corrected
null
null
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Developments of main notions and concepts behind the MSW effect (1978 - 1985) are described. They include (i) neutrino refraction, matter potential, and evolution equation in matter, (ii) mixing in matter, resonance and level crossing; (iii) adiabaticity condition and adiabatic propagation in matter with varying density. They are in the basis of the resonance enhancement of oscillations in matter with constant (nearly constant) density, and the adiabatic flavor conversion in matter with slowly changing density. The former is realized in matter of the Earth and can be used to establish neutrino mass hierarchy. The latter provides solution to the solar neutrino problem and play the key role in transformations of the supernova neutrinos.
[ { "created": "Thu, 31 Jan 2019 17:00:58 GMT", "version": "v1" }, { "created": "Mon, 4 Feb 2019 17:19:13 GMT", "version": "v2" } ]
2019-02-05
[ [ "Smirnov", "A Y", "" ] ]
Developments of main notions and concepts behind the MSW effect (1978 - 1985) are described. They include (i) neutrino refraction, matter potential, and evolution equation in matter, (ii) mixing in matter, resonance and level crossing; (iii) adiabaticity condition and adiabatic propagation in matter with varying density. They are in the basis of the resonance enhancement of oscillations in matter with constant (nearly constant) density, and the adiabatic flavor conversion in matter with slowly changing density. The former is realized in matter of the Earth and can be used to establish neutrino mass hierarchy. The latter provides solution to the solar neutrino problem and play the key role in transformations of the supernova neutrinos.
hep-ph/9912282
Ignacio Navarro
A. Ibarra and I. Navarro
Impact of radiative corrections on sterile neutrino scenarios
14 pages, LaTeX, 2 figures. Discussion enlarged, references added and typos corrected
JHEP 0002:031,2000
10.1088/1126-6708/2000/02/031
IEM-FT-199/99
hep-ph
null
In sterile neutrino scenarios, radiative corrections induce mass splittings proportional to the top Yukawa coupling, in contrast to the three active neutrino case where the induced splittings are proportional to the tau Yukawa coupling. In view of this, we have analyzed the stability of the four-neutrino schemes favored by oscillation experiments, consisting in two pairs of nearly degenerate neutrinos separated by the LSND gap. Requiring compatibility with the measurements of the abundances of primordial elements produced in Big Bang Nucleosynthesis, we find that when the heaviest pair corresponds to the solar neutrinos (mainly an admixture of nu_e - nu_s) the natural mass splitting is 3-5 orders of magnitude larger than the observed one, discrediting the scenario from a theoretical point of view. On the contrary, the scheme where the heaviest pair corresponds to the atmospheric neutrinos (mainly an admixture of nu_mu - nu_tau) is safe from radiative corrections due to the small sterile component of these mass eigenstates.
[ { "created": "Thu, 9 Dec 1999 19:53:27 GMT", "version": "v1" }, { "created": "Thu, 16 Mar 2000 12:58:02 GMT", "version": "v2" } ]
2010-02-03
[ [ "Ibarra", "A.", "" ], [ "Navarro", "I.", "" ] ]
In sterile neutrino scenarios, radiative corrections induce mass splittings proportional to the top Yukawa coupling, in contrast to the three active neutrino case where the induced splittings are proportional to the tau Yukawa coupling. In view of this, we have analyzed the stability of the four-neutrino schemes favored by oscillation experiments, consisting in two pairs of nearly degenerate neutrinos separated by the LSND gap. Requiring compatibility with the measurements of the abundances of primordial elements produced in Big Bang Nucleosynthesis, we find that when the heaviest pair corresponds to the solar neutrinos (mainly an admixture of nu_e - nu_s) the natural mass splitting is 3-5 orders of magnitude larger than the observed one, discrediting the scenario from a theoretical point of view. On the contrary, the scheme where the heaviest pair corresponds to the atmospheric neutrinos (mainly an admixture of nu_mu - nu_tau) is safe from radiative corrections due to the small sterile component of these mass eigenstates.
hep-ph/9407328
null
F. De Campos, M. A. Garcia-Jare\~NO, Anjan S. Joshipura, J. Rosiek, J. W. F. Valle and D. P. Roy
Limits on Associated Production of Visibly and Invisibly Decaying Higgs Bosons from Z Decays
FTUV/94-36, IFIC/94-31 TIFR/TH/94--25, 12 pages + 4 figures (included as ps files at the end)
Phys.Lett.B336:446-456,1994
10.1016/0370-2693(94)90557-6
null
hep-ph
null
Many extensions of the standard electroweak model Higgs sector suggest that the main Higgs decay channel is "invisible", for example, $h \to J J$ where $J$ denotes the majoron, a weakly interacting pseudoscalar Goldstone boson associated to the spontaneous violation of lepton number. In many of these models the Higgs boson may also be produced in association to a massive pseudoscalar boson (HA), in addition to the standard Bjorken mechanism (HZ). We describe a general strategy to determine limits from LEP data on the masses and couplings of such Higgs bosons, using the existing data on acoplanar dijet events as well as data on four and six $b$ jet event topologies. For the sake of illustration, we present constraints that can be obtained for the ALEPH data.
[ { "created": "Tue, 19 Jul 1994 14:53:15 GMT", "version": "v1" } ]
2009-09-25
[ [ "De Campos", "F.", "" ], [ "Garcia-JareÑO", "M. A.", "" ], [ "Joshipura", "Anjan S.", "" ], [ "Rosiek", "J.", "" ], [ "Valle", "J. W. F.", "" ], [ "Roy", "D. P.", "" ] ]
Many extensions of the standard electroweak model Higgs sector suggest that the main Higgs decay channel is "invisible", for example, $h \to J J$ where $J$ denotes the majoron, a weakly interacting pseudoscalar Goldstone boson associated to the spontaneous violation of lepton number. In many of these models the Higgs boson may also be produced in association to a massive pseudoscalar boson (HA), in addition to the standard Bjorken mechanism (HZ). We describe a general strategy to determine limits from LEP data on the masses and couplings of such Higgs bosons, using the existing data on acoplanar dijet events as well as data on four and six $b$ jet event topologies. For the sake of illustration, we present constraints that can be obtained for the ALEPH data.
hep-ph/9603365
Gogberashvili Merab
M.Gogberashvili, L.Midodashvili, P.Midodashvili
Temperature Shift of Neutrino Energy in the External Magnetic Field
8 pages, no macros, no figures, LaTEX
null
null
IPGAS-HE-1-96
hep-ph hep-th
null
It is evaluated the first order temperature correction to the energy of massive neutrino in the case of weak magnetic field.
[ { "created": "Wed, 20 Mar 1996 20:50:40 GMT", "version": "v1" } ]
2007-05-23
[ [ "Gogberashvili", "M.", "" ], [ "Midodashvili", "L.", "" ], [ "Midodashvili", "P.", "" ] ]
It is evaluated the first order temperature correction to the energy of massive neutrino in the case of weak magnetic field.
0904.0934
Jean Alexandre
Jean Alexandre
Inflaton in R-dependent potential
null
null
null
null
hep-ph gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider a non-minimally coupled inflaton, in a higher order curvature background, leading to a potential which evolves with the curvature scalar of the Universe, and which describes two regimes. The first one is a de Sitter phase, where the potential is static, and an exact exponential solution is found for the inflaton. The second regime, triggered by the inflaton reaching a threshold, leads to a power-law expansion, during which the potential becomes flat, quickly enough for the inflaton never to reach the minimum of the initial symmetry breaking potential. This scenario is an alternative to the inflaton oscillating about a minimum of the potential, and where preheating is a consequence of the flattening of the potential during the power-law expanding phase.
[ { "created": "Mon, 6 Apr 2009 14:40:28 GMT", "version": "v1" }, { "created": "Thu, 25 Mar 2010 14:41:34 GMT", "version": "v2" } ]
2015-03-13
[ [ "Alexandre", "Jean", "" ] ]
We consider a non-minimally coupled inflaton, in a higher order curvature background, leading to a potential which evolves with the curvature scalar of the Universe, and which describes two regimes. The first one is a de Sitter phase, where the potential is static, and an exact exponential solution is found for the inflaton. The second regime, triggered by the inflaton reaching a threshold, leads to a power-law expansion, during which the potential becomes flat, quickly enough for the inflaton never to reach the minimum of the initial symmetry breaking potential. This scenario is an alternative to the inflaton oscillating about a minimum of the potential, and where preheating is a consequence of the flattening of the potential during the power-law expanding phase.
1510.03437
Diego Aristizabal
D. Aristizabal Sierra, J. Herrero-Garcia, D. Restrepo, A. Vicente
Diboson anomaly: heavy Higgs resonance and QCD vector-like exotics
12 pages, 5 figures. One reference added, figures updated, results unchanged
Phys. Rev. D 93, 015012 (2016)
10.1103/PhysRevD.93.015012
IFIC/15-79
hep-ph hep-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The ATLAS collaboration (and also CMS) has recently reported an excess over Standard Model expectations for gauge boson pair production in the invariant mass region $1.8-2.2$ TeV. In the light of these results, we argue that such signal might be the first manifestation of the production and further decay of a heavy CP-even Higgs resulting from a type-I Two Higgs Doublet Model. We demonstrate that in the presence of colored vector-like fermions, its gluon fusion production cross-section is strongly enhanced, with the enhancement depending on the color representation of the new fermion states. Our findings show that barring the color triplet case, any QCD "exotic" representation can fit the ATLAS result in fairly large portions of the parameter space. We have found that if the diboson excess is confirmed and this mechanism is indeed responsible for it, then the LHC Run-2 should find: (i) a CP-odd scalar with mass below $\sim 2.3$ TeV, (ii) new colored states with masses below $\sim 2$ TeV, (iii) no statistically significant diboson events in the $W^\pm Z$ channel, (iv) events in the triboson channels $W^\pm W^\mp\,Z$ and $ZZZ$ with invariant mass amounting to the mass of the CP-odd scalar.
[ { "created": "Mon, 12 Oct 2015 20:13:03 GMT", "version": "v1" }, { "created": "Tue, 20 Oct 2015 18:54:44 GMT", "version": "v2" } ]
2016-01-27
[ [ "Sierra", "D. Aristizabal", "" ], [ "Herrero-Garcia", "J.", "" ], [ "Restrepo", "D.", "" ], [ "Vicente", "A.", "" ] ]
The ATLAS collaboration (and also CMS) has recently reported an excess over Standard Model expectations for gauge boson pair production in the invariant mass region $1.8-2.2$ TeV. In the light of these results, we argue that such signal might be the first manifestation of the production and further decay of a heavy CP-even Higgs resulting from a type-I Two Higgs Doublet Model. We demonstrate that in the presence of colored vector-like fermions, its gluon fusion production cross-section is strongly enhanced, with the enhancement depending on the color representation of the new fermion states. Our findings show that barring the color triplet case, any QCD "exotic" representation can fit the ATLAS result in fairly large portions of the parameter space. We have found that if the diboson excess is confirmed and this mechanism is indeed responsible for it, then the LHC Run-2 should find: (i) a CP-odd scalar with mass below $\sim 2.3$ TeV, (ii) new colored states with masses below $\sim 2$ TeV, (iii) no statistically significant diboson events in the $W^\pm Z$ channel, (iv) events in the triboson channels $W^\pm W^\mp\,Z$ and $ZZZ$ with invariant mass amounting to the mass of the CP-odd scalar.
1301.1554
Adam Smetana
Adam Smetana
Top-quark and neutrino composite Higgs bosons
12 pages, 4 figures, this third version is the one having been published in EPJC
The European Physical Journal C, 73:2513, August 2013
10.1140/epjc/s10052-013-2513-8
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the context of top-quark condensation models, the top-quark alone is too light to saturate the correct value of the electroweak scale by its condensate. Within the seesaw scenario the neutrinos can have their Dirac masses large enough so that their condensates can provide significant contribution to the value of the electroweak scale. We address the question of a phenomenological feasibility of the top-quark and neutrino condensation conspiracy against the electroweak symmetry. Mandatory is to reproduce the masses of electroweak gauge bosons, the top-quark mass and the recently observed scalar mass of $125\,\mathrm{GeV}$ and to satisfy the upper limits on absolute value of active neutrino masses. To accomplish that we design a reasonably simplified effective model with two composite Higgs doublets. Additionally, we work with a general number $N$ of right-handed neutrino flavor triplets participating on the seesaw mechanism. There are no experimental constraints limiting this number. The upper limit is set by the model itself. Provided that the condensation scale is of order $10^{17-18}\,\mathrm{GeV}$ and the number of right-handed neutrinos is ${\cal O}(100-1000)$, the model predicts masses of additional Higgs bosons below $250\,\mathrm{GeV}$ and a suppression of the top-quark Yukawa coupling to the $125\,\mathrm{GeV}$ particle at the $\sim60\,%$ level of the Standard model value.
[ { "created": "Tue, 8 Jan 2013 14:51:22 GMT", "version": "v1" }, { "created": "Wed, 27 Mar 2013 16:30:38 GMT", "version": "v2" }, { "created": "Thu, 19 Sep 2013 08:12:50 GMT", "version": "v3" } ]
2013-09-20
[ [ "Smetana", "Adam", "" ] ]
In the context of top-quark condensation models, the top-quark alone is too light to saturate the correct value of the electroweak scale by its condensate. Within the seesaw scenario the neutrinos can have their Dirac masses large enough so that their condensates can provide significant contribution to the value of the electroweak scale. We address the question of a phenomenological feasibility of the top-quark and neutrino condensation conspiracy against the electroweak symmetry. Mandatory is to reproduce the masses of electroweak gauge bosons, the top-quark mass and the recently observed scalar mass of $125\,\mathrm{GeV}$ and to satisfy the upper limits on absolute value of active neutrino masses. To accomplish that we design a reasonably simplified effective model with two composite Higgs doublets. Additionally, we work with a general number $N$ of right-handed neutrino flavor triplets participating on the seesaw mechanism. There are no experimental constraints limiting this number. The upper limit is set by the model itself. Provided that the condensation scale is of order $10^{17-18}\,\mathrm{GeV}$ and the number of right-handed neutrinos is ${\cal O}(100-1000)$, the model predicts masses of additional Higgs bosons below $250\,\mathrm{GeV}$ and a suppression of the top-quark Yukawa coupling to the $125\,\mathrm{GeV}$ particle at the $\sim60\,%$ level of the Standard model value.
2112.02769
Yaroslav Balytskyi
Yaroslav Balytskyi
Leptophobic dark photon interpretation of the $\eta^{\left(\prime\right)}\rightarrow\pi^0\left(\eta\right)\gamma\gamma$ puzzle
null
null
10.1016/j.physletb.2023.137668
null
hep-ph nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The decays of $\eta$ and $\eta^\prime$ mesons provide unique opportunities for testing the properties of low energy Quantum Chromodynamics and for the search of new physics beyond the Standard Model. However, recent experimental results on the rare decays of $\eta^{\left(\prime\right)}\rightarrow\pi^0\left(\eta\right)\gamma\gamma$ cannot be self-consistently described by the combination of the Vector Meson Dominance and Linear Sigma Model employing the same set of parameters. We show that this tension can be attributed to the presence of a leptophobic dark photon $\mathcal{B}$, and find representative values of the parameters which provide consistent description of these three decays, simultaneously. Unlike existing strategies of Dalitz analysis searching for the bump at $m_\mathcal{B}$, we propose the usage of mismatch between these decays to constrain the parameters of the hypothetical dark photon.
[ { "created": "Mon, 6 Dec 2021 03:49:40 GMT", "version": "v1" }, { "created": "Tue, 29 Mar 2022 18:38:53 GMT", "version": "v2" } ]
2023-01-11
[ [ "Balytskyi", "Yaroslav", "" ] ]
The decays of $\eta$ and $\eta^\prime$ mesons provide unique opportunities for testing the properties of low energy Quantum Chromodynamics and for the search of new physics beyond the Standard Model. However, recent experimental results on the rare decays of $\eta^{\left(\prime\right)}\rightarrow\pi^0\left(\eta\right)\gamma\gamma$ cannot be self-consistently described by the combination of the Vector Meson Dominance and Linear Sigma Model employing the same set of parameters. We show that this tension can be attributed to the presence of a leptophobic dark photon $\mathcal{B}$, and find representative values of the parameters which provide consistent description of these three decays, simultaneously. Unlike existing strategies of Dalitz analysis searching for the bump at $m_\mathcal{B}$, we propose the usage of mismatch between these decays to constrain the parameters of the hypothetical dark photon.
1208.0961
Pedro Bicudo
Nuno Cardoso, Pedro Bicudo, Ulrike Eilhauer, Ioanni Bouras
CuBA - a CUDA implementation of BAMPS
work done partly under the PTQCD Collaboration, contribution Presented by Ulrike Eilhauer at the International Meeting "Excited QCD", Peniche, Portugal, 06 - 12 May 2012
null
null
null
hep-ph physics.comp-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Using CUDA as programming language, we create a code named CuBA which is based on the CPU code "Boltzmann Approach for Many Parton Scattering (BAMPS)" developed in Frankfurt in order to study a system of many colliding particles resulting from heavy ion collisions. Furthermore, we benchmark our code with the Riemann Problem and compare the results with BAMPS. They demonstrate an improvement of the computational runtime, by one order of magitude.
[ { "created": "Sat, 4 Aug 2012 22:45:08 GMT", "version": "v1" } ]
2012-08-16
[ [ "Cardoso", "Nuno", "" ], [ "Bicudo", "Pedro", "" ], [ "Eilhauer", "Ulrike", "" ], [ "Bouras", "Ioanni", "" ] ]
Using CUDA as programming language, we create a code named CuBA which is based on the CPU code "Boltzmann Approach for Many Parton Scattering (BAMPS)" developed in Frankfurt in order to study a system of many colliding particles resulting from heavy ion collisions. Furthermore, we benchmark our code with the Riemann Problem and compare the results with BAMPS. They demonstrate an improvement of the computational runtime, by one order of magitude.
hep-ph/0608082
Carlo Ewerz
Carlo Ewerz, Otto Nachtmann
Chiral Symmetry and Diffractive Neutral Pion Photo- and Electroproduction
22 pages, 7 figures
Eur.Phys.J.C49:685-696,2007
10.1140/epjc/s10052-006-0082-9
ECT*-06-10, HD-THEP-06-16
hep-ph
null
We show that diffractive production of a single neutral pion in photon-induced reactions at high energy is dynamically suppressed due to the approximate chiral symmetry of QCD. These reactions have been proposed as a test of the odderon exchange mechanism. We show that the odderon contribution to the amplitude for such reactions vanishes exactly in the chiral limit. This result is obtained in a nonperturbative framework and by using PCAC relations between the amplitudes for neutral pion and axial vector current production.
[ { "created": "Mon, 7 Aug 2006 17:06:49 GMT", "version": "v1" } ]
2011-09-13
[ [ "Ewerz", "Carlo", "" ], [ "Nachtmann", "Otto", "" ] ]
We show that diffractive production of a single neutral pion in photon-induced reactions at high energy is dynamically suppressed due to the approximate chiral symmetry of QCD. These reactions have been proposed as a test of the odderon exchange mechanism. We show that the odderon contribution to the amplitude for such reactions vanishes exactly in the chiral limit. This result is obtained in a nonperturbative framework and by using PCAC relations between the amplitudes for neutral pion and axial vector current production.
0706.3921
Kaushik Bhattacharya
Alberto Bravo Garcia, Kaushik Bhattacharya, Sarira Sahu
The neutrino self-energy in a magnetized medium
13 Pages, Latex file. Minor corrections included. To be published in Modern Physics Letters A
Mod.Phys.Lett.A23:2771-2786,2008
10.1142/S0217732308028442
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work we calculate the neutrino self-energy in presence of a magnetized medium. The magnetized medium consists of electrons, positrons, neutrinos and a uniform classical magnetic field. The calculation is done assuming the background magnetic field is weak compared to the $W$-Boson mass squared, as a consequence of which only linear order corrections in the field are included in the $W$ boson propagator. The electron propagator consists all order corrections in the background field. Although the neutrino self-energy in a magnetized medium in various limiting cases has been calculated previously in this article we produce the most general expression of the self-energy in absence of the Landau quantization of the charged gauge fields. We calculate the effect of the Landau quantization of the charged leptons on the neutrino self-energy in the general case. Our calculation is specifically suited for situations where the background plasma may be CP symmetric.
[ { "created": "Wed, 27 Jun 2007 18:11:38 GMT", "version": "v1" }, { "created": "Fri, 20 Jul 2007 03:35:12 GMT", "version": "v2" }, { "created": "Tue, 23 Sep 2008 08:52:09 GMT", "version": "v3" } ]
2008-11-26
[ [ "Garcia", "Alberto Bravo", "" ], [ "Bhattacharya", "Kaushik", "" ], [ "Sahu", "Sarira", "" ] ]
In this work we calculate the neutrino self-energy in presence of a magnetized medium. The magnetized medium consists of electrons, positrons, neutrinos and a uniform classical magnetic field. The calculation is done assuming the background magnetic field is weak compared to the $W$-Boson mass squared, as a consequence of which only linear order corrections in the field are included in the $W$ boson propagator. The electron propagator consists all order corrections in the background field. Although the neutrino self-energy in a magnetized medium in various limiting cases has been calculated previously in this article we produce the most general expression of the self-energy in absence of the Landau quantization of the charged gauge fields. We calculate the effect of the Landau quantization of the charged leptons on the neutrino self-energy in the general case. Our calculation is specifically suited for situations where the background plasma may be CP symmetric.
hep-ph/9609531
Marc Kamionkowski
Marc Kamionkowski
Particle Dark Matter
13 pages, ReVTeX, to appear in the proceedings of the VIIIth Rencontres de Blois, Neutrinos, Dark Matter, and the Universe, June 8--12, 1996, Blois, France (fixed preprint number)
null
null
CU-TP-786, CAL-616
hep-ph astro-ph
null
Several ideas for new physics beyond the standard model may provide particle candidates for the dark matter in the Galactic halo. The two leading candidates are an axion and a weakly-interacting massive particle (WIMP), such as the neutralino in supersymmetric extensions of the standard model. Several possibilities for detection of such particles are discussed. An assessment of the relative merits of various WIMP-detection techniques is given. I then review the prospects for improving our knowledge of the amount, distribution, and nature of the dark matter in the Universe from future maps of the cosmic microwave background.
[ { "created": "Mon, 30 Sep 1996 18:16:20 GMT", "version": "v1" }, { "created": "Tue, 1 Oct 1996 11:30:59 GMT", "version": "v2" } ]
2008-02-03
[ [ "Kamionkowski", "Marc", "" ] ]
Several ideas for new physics beyond the standard model may provide particle candidates for the dark matter in the Galactic halo. The two leading candidates are an axion and a weakly-interacting massive particle (WIMP), such as the neutralino in supersymmetric extensions of the standard model. Several possibilities for detection of such particles are discussed. An assessment of the relative merits of various WIMP-detection techniques is given. I then review the prospects for improving our knowledge of the amount, distribution, and nature of the dark matter in the Universe from future maps of the cosmic microwave background.
1107.2163
Daniel Zenh\"ausern
Juan Garc\'ia-Bellido, Javier Rubio, Mikhail Shaposhnikov, Daniel Zenh\"ausern
Higgs-Dilaton Cosmology: From the Early to the Late Universe
null
null
10.1103/PhysRevD.84.123504
null
hep-ph astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider a minimal scale-invariant extension of the Standard Model of particle physics combined with Unimodular Gravity formulated in \cite{Shaposhnikov:2008xb}. This theory is able to describe not only an inflationary stage, related to the Standard Model Higgs field, but also a late period of Dark Energy domination, associated with an almost massless dilaton. A number of parameters can be fixed by inflationary physics, allowing to make specific predictions for any subsequent period. In particular, we derive a relation between the tilt of the primordial spectrum of scalar fluctuations, $n_s$, and the present value of the equation of state parameter of dark energy, $\omega_{DE}^0$. We find bounds for the scalar tilt, $n_s<0.97$, the associated running, $-0.0006<d\ln n_s/d\ln k\lesssim-0.00015$, and for the scalar-to-tensor ratio, $0.0009\lesssim r<0.0033$, which will be critically tested by the results of the Planck mission. For the equation of state of dark energy, the model predicts $\omega_{DE}^0>-1$. The relation between $n_s$ and $\omega_{DE}^0$ allows us to use the current observational bounds on $n_s$ to further constrain the dark energy equation of state to $0< 1+\omega_{DE}^0< 0.02$, which is to be confronted with future dark energy surveys.
[ { "created": "Mon, 11 Jul 2011 23:11:59 GMT", "version": "v1" } ]
2013-05-29
[ [ "García-Bellido", "Juan", "" ], [ "Rubio", "Javier", "" ], [ "Shaposhnikov", "Mikhail", "" ], [ "Zenhäusern", "Daniel", "" ] ]
We consider a minimal scale-invariant extension of the Standard Model of particle physics combined with Unimodular Gravity formulated in \cite{Shaposhnikov:2008xb}. This theory is able to describe not only an inflationary stage, related to the Standard Model Higgs field, but also a late period of Dark Energy domination, associated with an almost massless dilaton. A number of parameters can be fixed by inflationary physics, allowing to make specific predictions for any subsequent period. In particular, we derive a relation between the tilt of the primordial spectrum of scalar fluctuations, $n_s$, and the present value of the equation of state parameter of dark energy, $\omega_{DE}^0$. We find bounds for the scalar tilt, $n_s<0.97$, the associated running, $-0.0006<d\ln n_s/d\ln k\lesssim-0.00015$, and for the scalar-to-tensor ratio, $0.0009\lesssim r<0.0033$, which will be critically tested by the results of the Planck mission. For the equation of state of dark energy, the model predicts $\omega_{DE}^0>-1$. The relation between $n_s$ and $\omega_{DE}^0$ allows us to use the current observational bounds on $n_s$ to further constrain the dark energy equation of state to $0< 1+\omega_{DE}^0< 0.02$, which is to be confronted with future dark energy surveys.
hep-ph/9609340
null
S. Dawson (BNL)
DPF `96: The triumph of the Standard Model
Summary talk given at the 1996 DPF meeting, Minneapolis, Minn., Aug. 10-15, 1996; uses sprocl.sty, 8 pg
null
null
BNL-HET-SD-96/5
hep-ph
null
I summarize some of the highlights of the 1996 DPF meeting, paying particular attention to new measurements of the $W$, $Z$, and top quark masses. Precision electroweak measurements from LEP are discussed with emphasis on recent measurements of $R_b$ and values of the coupling constants $\alpha(M_Z^2)$ and $\alpha_s(M_Z^2)$ are presented. Taken as a whole, the data are in spectacular agreement with the predictions of the Standard Model.
[ { "created": "Thu, 12 Sep 1996 18:42:52 GMT", "version": "v1" } ]
2007-05-23
[ [ "Dawson", "S.", "", "BNL" ] ]
I summarize some of the highlights of the 1996 DPF meeting, paying particular attention to new measurements of the $W$, $Z$, and top quark masses. Precision electroweak measurements from LEP are discussed with emphasis on recent measurements of $R_b$ and values of the coupling constants $\alpha(M_Z^2)$ and $\alpha_s(M_Z^2)$ are presented. Taken as a whole, the data are in spectacular agreement with the predictions of the Standard Model.
hep-ph/0304143
Domenico Falcone
F. Buccella, D. Falcone
Bounds for the mass of the heaviest right-handed neutrino in SO(10) theories
7 pages, RevTex4. Few corrections
Mod.Phys.Lett.A18:1819-1824,2003
10.1142/S0217732303011757
DSF-12/2003
hep-ph
null
By relating the Dirac neutrino mass matrix to the mass of the charged fermions and assuming that the product of the masses of the two lightest left-handed neutrinos is of the order of $\Delta m^2_{sol}$, we derive, within a leptogenesis scenario, a range of values for the mass of the heaviest right-handed neutrino, centered around the scale of $B-L$ symmetry breaking in the SO(10) theory with Pati-Salam intermediate symmetry.
[ { "created": "Tue, 15 Apr 2003 14:23:20 GMT", "version": "v1" }, { "created": "Tue, 29 Apr 2003 08:22:47 GMT", "version": "v2" } ]
2014-11-17
[ [ "Buccella", "F.", "" ], [ "Falcone", "D.", "" ] ]
By relating the Dirac neutrino mass matrix to the mass of the charged fermions and assuming that the product of the masses of the two lightest left-handed neutrinos is of the order of $\Delta m^2_{sol}$, we derive, within a leptogenesis scenario, a range of values for the mass of the heaviest right-handed neutrino, centered around the scale of $B-L$ symmetry breaking in the SO(10) theory with Pati-Salam intermediate symmetry.
2406.16286
German Valencia
German Valencia
Pursue of CP violation in hyperon decay
Invited contribution to FTCF2024, to appear in International Journal of Modern Physics A: (Special Issue: FTCF 2024)
null
null
null
hep-ph
http://creativecommons.org/licenses/by/4.0/
I review the status of CP violation in hyperon decay in light of recent progress by BESIII and the anticipated improvements at the super tau-charm facility. I emphasize the complementarity between kaons and hyperons for studying CP violation in $|\Delta S|=1,2$ processes.
[ { "created": "Mon, 24 Jun 2024 03:21:33 GMT", "version": "v1" } ]
2024-06-25
[ [ "Valencia", "German", "" ] ]
I review the status of CP violation in hyperon decay in light of recent progress by BESIII and the anticipated improvements at the super tau-charm facility. I emphasize the complementarity between kaons and hyperons for studying CP violation in $|\Delta S|=1,2$ processes.
1412.6679
Antonio Bouzas
I. A. Sarmiento-Alvarado, Antonio O. Bouzas and F. Larios
Analysis of the top-quark charged-current coupling at the LHeC
49 pages, 17 figures, final version to appear in JPG
null
null
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the context of $SU(2)_L\times U(1)$ dimension six operators we study the potential of the LHeC to provide information on top quark effective interactions. We focus on single antitop production and how it is affected not only by the effective $tbW$ coupling but also by four-fermion operators. Compared to the LHC, the LHeC provides a cleaner environment to make a precise measurement of the top quark production cross section. Therefore, this machine would give a much better assesment of $V_{tb}$ in the context of the SM or $V_L$ in the context of higher dimension operators. The LHeC could also give a slightly better measurement for $V_R$. For $g_R$ the HL-LHC precise measurements of $F_L$ and $F_R$ (the $W$-boson helicity decay ratios of top) would yield better constraints than those obtained by the LHeC. Lepton-quark contact interactions would also be significantly better probed by the LHeC, since the only way of measuring them at the LHC would be through leptonic top decay which is hardly sensitive to these interactions.
[ { "created": "Sat, 20 Dec 2014 19:02:29 GMT", "version": "v1" }, { "created": "Tue, 2 Jun 2015 14:54:54 GMT", "version": "v2" } ]
2015-06-03
[ [ "Sarmiento-Alvarado", "I. A.", "" ], [ "Bouzas", "Antonio O.", "" ], [ "Larios", "F.", "" ] ]
In the context of $SU(2)_L\times U(1)$ dimension six operators we study the potential of the LHeC to provide information on top quark effective interactions. We focus on single antitop production and how it is affected not only by the effective $tbW$ coupling but also by four-fermion operators. Compared to the LHC, the LHeC provides a cleaner environment to make a precise measurement of the top quark production cross section. Therefore, this machine would give a much better assesment of $V_{tb}$ in the context of the SM or $V_L$ in the context of higher dimension operators. The LHeC could also give a slightly better measurement for $V_R$. For $g_R$ the HL-LHC precise measurements of $F_L$ and $F_R$ (the $W$-boson helicity decay ratios of top) would yield better constraints than those obtained by the LHeC. Lepton-quark contact interactions would also be significantly better probed by the LHeC, since the only way of measuring them at the LHC would be through leptonic top decay which is hardly sensitive to these interactions.
hep-ph/9209251
null
Rohini M. Godbole, Probir Roy and Xerxes Tata
Tau Signals of R-parity breaking at LEP 200
27 pages in PHYZZX, six figures (not included, available on request). TIFR/TH/92-29,UH-511-751-92,CERN-TH.6613/92
Nucl.Phys. B401 (1993) 67-92
10.1016/0550-3213(93)90298-4
null
hep-ph
null
The detectability at LEP 200 of explicit $R$-parity breaking by tau-number $(L_\tau)$ violating operators is considered. The assumption of $L_\tau$-violation is motivated by the relative lack of constraints on such couplings but similar considerations apply to explicit $L_e$- or $L_\mu$-violation. The $LSP$, now unstable, and not necessarily neutral, decays via $L_\tau$-violating modes. Only signals from the production and decays of $LSP$ pairs are considered, thereby avoiding any dependence on the sparticle mass spectrum. Rather spectacular signals are predicted: spherical events with $m$ leptons (usually containing at least one $\tau$) and $n$ jets $(m,n \leq 4)$, the most characteristic of which are like-sign $\tau\tau$ events. These signals are enumerated for each $LSP$ candidate and quantitative estimates are provided for the favoured case when the $LSP$ is a neutralino. Other new physics signals, which can mimic these signatures, are also briefly discussed.
[ { "created": "Fri, 18 Sep 1992 12:11:45 GMT", "version": "v1" } ]
2009-10-22
[ [ "Godbole", "Rohini M.", "" ], [ "Roy", "Probir", "" ], [ "Tata", "Xerxes", "" ] ]
The detectability at LEP 200 of explicit $R$-parity breaking by tau-number $(L_\tau)$ violating operators is considered. The assumption of $L_\tau$-violation is motivated by the relative lack of constraints on such couplings but similar considerations apply to explicit $L_e$- or $L_\mu$-violation. The $LSP$, now unstable, and not necessarily neutral, decays via $L_\tau$-violating modes. Only signals from the production and decays of $LSP$ pairs are considered, thereby avoiding any dependence on the sparticle mass spectrum. Rather spectacular signals are predicted: spherical events with $m$ leptons (usually containing at least one $\tau$) and $n$ jets $(m,n \leq 4)$, the most characteristic of which are like-sign $\tau\tau$ events. These signals are enumerated for each $LSP$ candidate and quantitative estimates are provided for the favoured case when the $LSP$ is a neutralino. Other new physics signals, which can mimic these signatures, are also briefly discussed.
1210.2572
Jayanta Sarma Kumar
Mayuri Devee, R. Baishya and J. K. Sarma
Evolution of singlet structure functions from DGLAP equation at next-to-next-to-leading order at small-x
26 pages, 6 figures
Eur. Phys. J. C (2012) 72:2036
10.1140/epjc/s10052-012-2036-8
null
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A semi-numerical solution to Dokshitzer- Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations at leading order (LO), next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) in the small-x limit is presented. Here we have used Taylor series expansion method to solve the evolution equations and, t- and x-evolutions of the singlet structure functions have been obtained with such solution. We have also calculated t- and x-evolutions of deuteron structure functions F_2^d, and the results are compared with the E665 data and NMC data. The results are also compared to those obtained by the fit to F_2^d produced by the NNPDF collaboration based on the NMC and BCDMS data.
[ { "created": "Tue, 9 Oct 2012 11:48:33 GMT", "version": "v1" } ]
2012-10-10
[ [ "Devee", "Mayuri", "" ], [ "Baishya", "R.", "" ], [ "Sarma", "J. K.", "" ] ]
A semi-numerical solution to Dokshitzer- Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations at leading order (LO), next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) in the small-x limit is presented. Here we have used Taylor series expansion method to solve the evolution equations and, t- and x-evolutions of the singlet structure functions have been obtained with such solution. We have also calculated t- and x-evolutions of deuteron structure functions F_2^d, and the results are compared with the E665 data and NMC data. The results are also compared to those obtained by the fit to F_2^d produced by the NNPDF collaboration based on the NMC and BCDMS data.
1108.2197
Ahmed Ali
Ahmed Ali (DESY)
Theory Overview on Spectroscopy
14 pages, 6 figures,to be published in the Proceedings of the 13th. International Conference at Hadron Machines - Beauty2011, April 04-08, 2011, Amsterdam, The Netherlands
null
null
DESY 11-136
hep-ph hep-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A theoretical overview of the exotic spectroscopy in the charm and beauty quark sector is presented. These states are unexpected harvest from the $e^+e^-$ and hadron colliders and a permanent abode for the majority of them has yet to be found. We argue that some of these states, in particular the $Y_b(10890)$ and the recently discovered states $Z_b(10610)$ and $Z_b(10650)$, discovered by the Belle collaboration are excellent candidates for tetraquark states $[bq][\bar{b}\bar{q}]$, with $q=u,d$ light quarks. Theoretical analyes of the Belle data carried out in the tetraquark context is reviewed.
[ { "created": "Wed, 10 Aug 2011 15:17:52 GMT", "version": "v1" } ]
2011-08-30
[ [ "Ali", "Ahmed", "", "DESY" ] ]
A theoretical overview of the exotic spectroscopy in the charm and beauty quark sector is presented. These states are unexpected harvest from the $e^+e^-$ and hadron colliders and a permanent abode for the majority of them has yet to be found. We argue that some of these states, in particular the $Y_b(10890)$ and the recently discovered states $Z_b(10610)$ and $Z_b(10650)$, discovered by the Belle collaboration are excellent candidates for tetraquark states $[bq][\bar{b}\bar{q}]$, with $q=u,d$ light quarks. Theoretical analyes of the Belle data carried out in the tetraquark context is reviewed.
1511.08921
Wan-Zhe Feng
Wan-Zhe Feng, Zuowei Liu and Pran Nath
ATLAS Diboson Excess from Stueckelberg Mechanism
12 pages, 6 figures
JHEP 1604 (2016) 090
10.1007/JHEP04(2016)090
MPP-2015-274
hep-ph hep-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We discuss the diboson excess seen by the ATLAS detector around 2 TeV in the LHC run I at $\sqrt{s}=8$ TeV. We explore the possibility that such an excess can arise from a $Z'$ boson which acquires mass through a $U(1)_X$ Stueckelberg extension. The corresponding $Z'$ gauge boson is leptophobic with a mass of around 2 TeV and has interactions with $SU(2)_L$ Yang-Mills fields and gauge fields of the hypercharge. The analysis predicts $Z'$ decays into $WW$ and $ZZ$ as well as into $Z\gamma$. Further three-body as well as four-body decays of the $Z'$ such as $WWZ, WW\gamma, WWZZ$ etc are predicted. In the analysis we use the helicity formalism which allows us to exhibit the helicity structure of the $Z'$ decay processes in an transparent manner. In particular, we are able to show the set of vanishing helicity amplitudes in the decay of the massive $Z'$ into two vector bosons due to angular momentum conservation with a special choice of the reference momenta. The residual set of non-vanishing helicity amplitudes are identified. The parameter space of the model compatible with the diboson excess seen by the ATLAS experiment at $\sqrt s=8$ TeV is exhibited. Estimate of the diboson excess expected at $\sqrt s= 13$ TeV with 20 fb$^{-1}$ of integrated luminosity at LHC run II is also given. It is shown that the $WW$, $ZZ$ and $Z\gamma$ modes are predicted to be in the approximate ratio $1:\cos^2\theta_W (1+ \alpha \tan^2\theta_W)^2/2: (1-\alpha)^2\sin^2\theta_W/2$ where $\alpha$ is the relative strength of the couplings of hypercharge gauge fields to the couplings of the Yang-Mills gauge fields. Thus observation of the $Z\gamma$ mode as well as three-body and four-body decay modes of the $Z'$ will provide a definite test of the model and of a possible new source of interaction beyond the standard model.
[ { "created": "Sat, 28 Nov 2015 19:27:32 GMT", "version": "v1" }, { "created": "Fri, 1 Apr 2016 19:59:00 GMT", "version": "v2" }, { "created": "Wed, 8 Jun 2016 19:51:00 GMT", "version": "v3" } ]
2016-06-09
[ [ "Feng", "Wan-Zhe", "" ], [ "Liu", "Zuowei", "" ], [ "Nath", "Pran", "" ] ]
We discuss the diboson excess seen by the ATLAS detector around 2 TeV in the LHC run I at $\sqrt{s}=8$ TeV. We explore the possibility that such an excess can arise from a $Z'$ boson which acquires mass through a $U(1)_X$ Stueckelberg extension. The corresponding $Z'$ gauge boson is leptophobic with a mass of around 2 TeV and has interactions with $SU(2)_L$ Yang-Mills fields and gauge fields of the hypercharge. The analysis predicts $Z'$ decays into $WW$ and $ZZ$ as well as into $Z\gamma$. Further three-body as well as four-body decays of the $Z'$ such as $WWZ, WW\gamma, WWZZ$ etc are predicted. In the analysis we use the helicity formalism which allows us to exhibit the helicity structure of the $Z'$ decay processes in an transparent manner. In particular, we are able to show the set of vanishing helicity amplitudes in the decay of the massive $Z'$ into two vector bosons due to angular momentum conservation with a special choice of the reference momenta. The residual set of non-vanishing helicity amplitudes are identified. The parameter space of the model compatible with the diboson excess seen by the ATLAS experiment at $\sqrt s=8$ TeV is exhibited. Estimate of the diboson excess expected at $\sqrt s= 13$ TeV with 20 fb$^{-1}$ of integrated luminosity at LHC run II is also given. It is shown that the $WW$, $ZZ$ and $Z\gamma$ modes are predicted to be in the approximate ratio $1:\cos^2\theta_W (1+ \alpha \tan^2\theta_W)^2/2: (1-\alpha)^2\sin^2\theta_W/2$ where $\alpha$ is the relative strength of the couplings of hypercharge gauge fields to the couplings of the Yang-Mills gauge fields. Thus observation of the $Z\gamma$ mode as well as three-body and four-body decay modes of the $Z'$ will provide a definite test of the model and of a possible new source of interaction beyond the standard model.
hep-ph/0403239
Thorsten Renk
Thorsten Renk
A comprehensive description of multiple observables in heavy-ion collisions at SPS
21 pages, 10 figures, submitted to J. Phys. G
J.Phys. G30 (2004) 1495
10.1088/0954-3899/30/10/015
DUKE-TH-04-262
hep-ph
null
Combining and expanding on work from previous publications, a model for the evolution of ultrarelativistic heavy-ion collisions at the CERN SPS for 158 AGeV beam energy is presented. Based on the assumption of thermalization and a parametrization of the space-time expansion of the produced matter, this model is able to describe a large set of observables including hadronic momentum spectra, correlations and abundancies, the emission of real photons, dilepton radiation and the suppression pattern of charmonia. Each of these obervables provides unique capabilities to study the reaction dynamics and taken together they form a strong and consistent picture of the evolving system. Based on the emission of hard photons, we argue that a strongly interacting, hot and dense system with temperatures above 250 MeV has to be created early in the reaction. Such a system is bound to be different from hadronic matter and likely to be a quark-gluon plasma, and we find that this assumption is in line with the subsequent evolution of the system that is reflected in other observables.
[ { "created": "Mon, 22 Mar 2004 15:42:09 GMT", "version": "v1" }, { "created": "Tue, 17 Aug 2004 15:26:21 GMT", "version": "v2" } ]
2009-11-10
[ [ "Renk", "Thorsten", "" ] ]
Combining and expanding on work from previous publications, a model for the evolution of ultrarelativistic heavy-ion collisions at the CERN SPS for 158 AGeV beam energy is presented. Based on the assumption of thermalization and a parametrization of the space-time expansion of the produced matter, this model is able to describe a large set of observables including hadronic momentum spectra, correlations and abundancies, the emission of real photons, dilepton radiation and the suppression pattern of charmonia. Each of these obervables provides unique capabilities to study the reaction dynamics and taken together they form a strong and consistent picture of the evolving system. Based on the emission of hard photons, we argue that a strongly interacting, hot and dense system with temperatures above 250 MeV has to be created early in the reaction. Such a system is bound to be different from hadronic matter and likely to be a quark-gluon plasma, and we find that this assumption is in line with the subsequent evolution of the system that is reflected in other observables.
2107.11788
Mohamed Jakha
M. Baouahi, M. Ouali, M. Jakha, S. Mouslih, Y. Attaourti, B. Manaut and S. Taj
Laser-assisted kaon decay and CPT symmetry violation
17 pages, 5 figures, 2 tables
null
10.1088/1612-202X/ac1e86
null
hep-ph quant-ph
http://creativecommons.org/licenses/by/4.0/
In this paper, we have investigated the charged kaons decay at the lowest order in the presence of a circularly polarized laser field. To be more precise, we have examined the leptonic decay of both positive (matter) and negative (antimatter) kaon which weakly decay via the exchange of $W$ boson. Indeed, we have derived the expression of the leptonic decay width, the leptonic branching ratio, the leptonic ratio and the charged kaon lifetime by using the decay matrix approach. In addition, by using numerical computation, we have presented and discussed how the laser field influences these physical quantities. Moreover, we have analyzed the effect of the laser field on the parameter associated with the CPT symmetry. Then, we have concluded that, in the presence of an electromagnetic field and based on this CPT symmetry parameter, it is possible to control the dominance of matter over antimatter or vice-versa by applying an external field to either violate or conserve the CPT symmetry.
[ { "created": "Sun, 25 Jul 2021 11:40:36 GMT", "version": "v1" } ]
2021-09-22
[ [ "Baouahi", "M.", "" ], [ "Ouali", "M.", "" ], [ "Jakha", "M.", "" ], [ "Mouslih", "S.", "" ], [ "Attaourti", "Y.", "" ], [ "Manaut", "B.", "" ], [ "Taj", "S.", "" ] ]
In this paper, we have investigated the charged kaons decay at the lowest order in the presence of a circularly polarized laser field. To be more precise, we have examined the leptonic decay of both positive (matter) and negative (antimatter) kaon which weakly decay via the exchange of $W$ boson. Indeed, we have derived the expression of the leptonic decay width, the leptonic branching ratio, the leptonic ratio and the charged kaon lifetime by using the decay matrix approach. In addition, by using numerical computation, we have presented and discussed how the laser field influences these physical quantities. Moreover, we have analyzed the effect of the laser field on the parameter associated with the CPT symmetry. Then, we have concluded that, in the presence of an electromagnetic field and based on this CPT symmetry parameter, it is possible to control the dominance of matter over antimatter or vice-versa by applying an external field to either violate or conserve the CPT symmetry.
0902.3048
Ikaros Bigi
I.I. Bigi
Could Charm's "Third Time" Be the Real Charm? -- A Manifesto
15 pages, no figures; write-up of talk given to the LHCb Collab. in November 2008 at CERN
null
null
UND-HEP-09-BIG01
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The recent observation of $D^0 - \bar D^0$ oscillations has left us in a quandary concerning the theoretical interpretation: are they driven by SM forces alone or do they involve new dynamics? A comprehensive analysis of \cp symmetry in $D$ decays can probably resolve the issue. Charm studies might thus haul in their biggest prize yet: clear evidence for the intervention of New Physics. While the absolute size of \cp asymmetries will presumably be modest at best, SM contributions should be much smaller still. Thus the ratio of `signal' to `noise' -- i.e. NP over SM contributions -- might well be larger for $D$ than $B$ transitions. A typical list of promising channels is provided, most of which should be observable in a hadronic environment. Valuable lessons can be obtained by analyzing three- and four-body final states.
[ { "created": "Wed, 18 Feb 2009 05:26:17 GMT", "version": "v1" } ]
2009-02-19
[ [ "Bigi", "I. I.", "" ] ]
The recent observation of $D^0 - \bar D^0$ oscillations has left us in a quandary concerning the theoretical interpretation: are they driven by SM forces alone or do they involve new dynamics? A comprehensive analysis of \cp symmetry in $D$ decays can probably resolve the issue. Charm studies might thus haul in their biggest prize yet: clear evidence for the intervention of New Physics. While the absolute size of \cp asymmetries will presumably be modest at best, SM contributions should be much smaller still. Thus the ratio of `signal' to `noise' -- i.e. NP over SM contributions -- might well be larger for $D$ than $B$ transitions. A typical list of promising channels is provided, most of which should be observable in a hadronic environment. Valuable lessons can be obtained by analyzing three- and four-body final states.
1008.1834
Koichi Yamawaki
Koichi Yamawaki
Conformal Higgs, or techni-dilaton- composite Higgs near conformality
17 pages, 3 figures, to be published in Proceedings of 2009 Nagoya Global COE Workshop "Strong Coupling Gauge Theories in LHC Era" in Honor of Toshihide Maskawa's 70th Birthday and 35th Anniversary of Dynamical Symmetry Breaking in SCGT (SCGT 09), Dec. 8-11, 2009, Nagoya University, Nagoya 464-8602, Japan (World Scientific Co., Singapore)
Int.J.Mod.Phys.A25:5128-5144,2010
10.1142/S0217751X10050913
null
hep-ph hep-lat hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In contrast to the folklore that Technicolor (TC) is a "Higgsless theory", we shall discuss existence of a composite Higgs boson, Techni-Dilaton (TD), a pseudo-Nambu-Goldstone boson of the scale invariance in the Scale-invariant/Walking/Conformal TC (SWC TC) which generates a large anomalous dimension $\gamma_m \simeq 1$ in a wide region from the dynamical mass $m$ $= {\cal O}$ (TeV) of the techni-fermion all the way up to the intrinsic scale $\Lambda_{\rm TC}$ of the SWC TC (analogue of $\Lambda_{\rm QCD}$), where $\Lambda_{\rm TC} $ is taken typically as the scale of the Extended TC scale $\Lambda_{\rm ETC}$: $\Lambda_{\rm TC} \simeq \Lambda_{\rm ETC}\sim10^3$ TeV $ (\gg m)$. All the techni-hadrons have mass on the same order ${\cal O} (m)$, which in SWC TC is extremely smaller than the intrinsic scale $\Lambda_{\rm TC} \simeq \Lambda_{\rm ETC} $, in sharp contrast to QCD where both are of the same order. The mass of TD arises from the {\it non-perturbative scale anomaly} associated with the techni-fermion mass generation and is typically 500-600 GeV, even {\it smaller than other techni-hadrons} of the same order of ${\cal O} (m)$, in another contrast to QCD which is believed to have no scalar $\bar q q$ bound state lighter than other hadrons. We discuss the TD mass in various methods, Gauged NJL model via ladder Schwinger-Dyson (SD) equation, straightforward calculations in the ladder SD/ Bethe-Salpeter equation, and the holographic approach including techni-gluon condensate. The TD may be discovered in LHC.
[ { "created": "Wed, 11 Aug 2010 05:43:21 GMT", "version": "v1" } ]
2010-11-15
[ [ "Yamawaki", "Koichi", "" ] ]
In contrast to the folklore that Technicolor (TC) is a "Higgsless theory", we shall discuss existence of a composite Higgs boson, Techni-Dilaton (TD), a pseudo-Nambu-Goldstone boson of the scale invariance in the Scale-invariant/Walking/Conformal TC (SWC TC) which generates a large anomalous dimension $\gamma_m \simeq 1$ in a wide region from the dynamical mass $m$ $= {\cal O}$ (TeV) of the techni-fermion all the way up to the intrinsic scale $\Lambda_{\rm TC}$ of the SWC TC (analogue of $\Lambda_{\rm QCD}$), where $\Lambda_{\rm TC} $ is taken typically as the scale of the Extended TC scale $\Lambda_{\rm ETC}$: $\Lambda_{\rm TC} \simeq \Lambda_{\rm ETC}\sim10^3$ TeV $ (\gg m)$. All the techni-hadrons have mass on the same order ${\cal O} (m)$, which in SWC TC is extremely smaller than the intrinsic scale $\Lambda_{\rm TC} \simeq \Lambda_{\rm ETC} $, in sharp contrast to QCD where both are of the same order. The mass of TD arises from the {\it non-perturbative scale anomaly} associated with the techni-fermion mass generation and is typically 500-600 GeV, even {\it smaller than other techni-hadrons} of the same order of ${\cal O} (m)$, in another contrast to QCD which is believed to have no scalar $\bar q q$ bound state lighter than other hadrons. We discuss the TD mass in various methods, Gauged NJL model via ladder Schwinger-Dyson (SD) equation, straightforward calculations in the ladder SD/ Bethe-Salpeter equation, and the holographic approach including techni-gluon condensate. The TD may be discovered in LHC.
hep-ph/9502312
Brian Harris
B. W. Harris and J. Smith (ITP-Stony Brook)
Invariant mass distributions for heavy quark-antiquark pairs in deep inelastic electroproduction
Submitted to Phys. Lett. B, 10 pages LaTeX plus 8 figures attached as a uuencoded compressed tarred Postscript file. Complete Postsript version, including figures, available at ftp://insti.physics.sunysb.edu/preprints/harris/eplett.tar.Z(.gz)
Phys.Lett.B353:535-540,1995; ERRATUM-ibid.B359:423,1995
10.1016/0370-2693(95)00571-2
ITP-SB-94-06
hep-ph
null
We have completed the ${\cal O}(\alpha_s)$ QCD corrections to exclusive heavy quark-antiquark distributions in deep inelastic electroproduction and present here the differential distributions in the masses of charm-anticharm and bottom-antibottom pairs at the electron-proton collider HERA.
[ { "created": "Wed, 15 Feb 1995 22:40:01 GMT", "version": "v1" } ]
2016-09-01
[ [ "Harris", "B. W.", "", "ITP-Stony Brook" ], [ "Smith", "J.", "", "ITP-Stony Brook" ] ]
We have completed the ${\cal O}(\alpha_s)$ QCD corrections to exclusive heavy quark-antiquark distributions in deep inelastic electroproduction and present here the differential distributions in the masses of charm-anticharm and bottom-antibottom pairs at the electron-proton collider HERA.
hep-ph/0411124
Dan Pirjol
Dan Pirjol
Factorization in color-suppressed B -> D(*)0 pi0 decays from the soft-collinear effective theory
4 pages, 2 figures, uses ws-procs10x7.cls. Contribution to the Proceedings of the 32nd International Conference on High Energy Physics (ICHEP04), 16-22 August 2004, Beijing, China
null
10.1142/9789812702227_0150
null
hep-ph
null
The soft-collinear effective theory has been recently applied to prove novel factorization theorems for many B decays. We describe here in some detail the factorization relation for color-supressed nonleptonic B -> D(*)0 pi0 decays and update the phenomenological analysis of these decays.
[ { "created": "Mon, 8 Nov 2004 20:25:26 GMT", "version": "v1" } ]
2017-08-23
[ [ "Pirjol", "Dan", "" ] ]
The soft-collinear effective theory has been recently applied to prove novel factorization theorems for many B decays. We describe here in some detail the factorization relation for color-supressed nonleptonic B -> D(*)0 pi0 decays and update the phenomenological analysis of these decays.
hep-ph/0409100
Wei-Qin Zhao
Zhao Zhang, Wei-qin Zhao
Mixed tensor susceptibility of the QCD vacuum from effective quark-quark interactions
12 pages
Phys.Lett. B612 (2005) 207-214
10.1016/j.physletb.2005.03.012
null
hep-ph
null
We calculate the mixed tensor susceptibility of QCD vacuum in the framework of the global color symmetry model. In our calculation, the functional integration over gluon fields can be performed and the gluonic vacuum observable can be expressed in terms of the quark operators and the gluon propagator. The mixed tensor susceptibility was obtained with the subtraction of the perturbative contribution which is evaluated by the Wigner solution of the quark gap equation. Using several different effective quark-quark interaction models, we find the values of the mixed tensor susceptibility are very small.
[ { "created": "Thu, 9 Sep 2004 02:54:01 GMT", "version": "v1" } ]
2009-11-10
[ [ "Zhang", "Zhao", "" ], [ "Zhao", "Wei-qin", "" ] ]
We calculate the mixed tensor susceptibility of QCD vacuum in the framework of the global color symmetry model. In our calculation, the functional integration over gluon fields can be performed and the gluonic vacuum observable can be expressed in terms of the quark operators and the gluon propagator. The mixed tensor susceptibility was obtained with the subtraction of the perturbative contribution which is evaluated by the Wigner solution of the quark gap equation. Using several different effective quark-quark interaction models, we find the values of the mixed tensor susceptibility are very small.
hep-ph/9607455
Adrian Ghinculov
Adrian Ghinculov
Two-loop effects of enhanced electroweak strength in the Higgs sector
To be published in the proceedings of 9th International Seminar on High-energy Physics: Quarks 96, Yaroslavl, Russia, 5-11 May 1996, e-print numbers added to preprint references in revised version
Helv.Phys.Acta 70:822-837,1997
null
Freiburg-THEP 96/14
hep-ph
null
The selfcoupling of the Higgs field grows with the mass of the Higgs particle and induces potentially large radiative corrections in the electroweak model. The technical aspects of performing multiloop calculations in the massive case are discussed briefly. I review the status of two-loop calculations of radiative corrections of enhanced electroweak strength which are relevant for the Higgs physics. I discuss the relevance of the existing results with respect to heavy Higgs searches at future colliders and their implications regarding the validity range of perturbation theory.
[ { "created": "Sun, 28 Jul 1996 17:16:21 GMT", "version": "v1" }, { "created": "Sun, 11 Aug 1996 20:42:33 GMT", "version": "v2" } ]
2014-11-17
[ [ "Ghinculov", "Adrian", "" ] ]
The selfcoupling of the Higgs field grows with the mass of the Higgs particle and induces potentially large radiative corrections in the electroweak model. The technical aspects of performing multiloop calculations in the massive case are discussed briefly. I review the status of two-loop calculations of radiative corrections of enhanced electroweak strength which are relevant for the Higgs physics. I discuss the relevance of the existing results with respect to heavy Higgs searches at future colliders and their implications regarding the validity range of perturbation theory.
1211.6739
Torsten Bringmann
Masaki Asano, Torsten Bringmann, Gunter Sigl, Martin Vollmann
The 130 GeV gamma-ray line and generic dark matter model building constraints from continuum gamma rays, radio and antiproton data
16 pages revtex4; 4 figures. Fixed typos and slightly extended discussion, including constraints for scalar DM case. Matches published version
Phys. Rev. D 87, 103509 (2013)
10.1103/PhysRevD.87.103509
null
hep-ph astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
An analysis of the Fermi gamma ray space telescope data has recently revealed a resolved gamma-ray feature close to the galactic center which is consistent with monochromatic photons at an energy of about 130 GeV. If interpreted in terms of dark matter (DM) annihilating into \gamma\gamma (\gamma Z, \gamma h), this would correspond to a DM particle mass of roughly 130 GeV (145 GeV, 155 GeV). The rate for these loop-suppressed processes, however, is larger than typically expected for thermally produced DM. Correspondingly, one would generically expect even larger tree level production rates of standard model fermions or gauge bosons. Here, we quantify this expectation in a rather model-independent way by relating the tree level and loop amplitudes with the help of the optical theorem. As an application, we consider bounds from continuum gamma rays, radio and antiproton data on the tree level amplitudes and translate them into constraints on the loop amplitudes. We find that, independently of the DM production mechanism, any DM model aiming at explaining the line signal in terms of charged standard model particles running in the loop is in rather strong tension with at least one of these constraints, with the exception of loops dominated by top quarks. We stress that attempts to explain the 130 GeV feature with internal bremsstrahlung do not suffer from such difficulties.
[ { "created": "Wed, 28 Nov 2012 21:00:00 GMT", "version": "v1" }, { "created": "Thu, 16 May 2013 14:21:28 GMT", "version": "v2" } ]
2013-05-17
[ [ "Asano", "Masaki", "" ], [ "Bringmann", "Torsten", "" ], [ "Sigl", "Gunter", "" ], [ "Vollmann", "Martin", "" ] ]
An analysis of the Fermi gamma ray space telescope data has recently revealed a resolved gamma-ray feature close to the galactic center which is consistent with monochromatic photons at an energy of about 130 GeV. If interpreted in terms of dark matter (DM) annihilating into \gamma\gamma (\gamma Z, \gamma h), this would correspond to a DM particle mass of roughly 130 GeV (145 GeV, 155 GeV). The rate for these loop-suppressed processes, however, is larger than typically expected for thermally produced DM. Correspondingly, one would generically expect even larger tree level production rates of standard model fermions or gauge bosons. Here, we quantify this expectation in a rather model-independent way by relating the tree level and loop amplitudes with the help of the optical theorem. As an application, we consider bounds from continuum gamma rays, radio and antiproton data on the tree level amplitudes and translate them into constraints on the loop amplitudes. We find that, independently of the DM production mechanism, any DM model aiming at explaining the line signal in terms of charged standard model particles running in the loop is in rather strong tension with at least one of these constraints, with the exception of loops dominated by top quarks. We stress that attempts to explain the 130 GeV feature with internal bremsstrahlung do not suffer from such difficulties.
0810.1876
Guy F. de T\'eramond
Stanley J. Brodsky and Guy F. de Teramond
The AdS/CFT Correspondence and Light-Front QCD
12 pages, 4 figures. Presented by SJB at LIGHT CONE 2008: Relativistic Nuclear and Particle Physics
null
null
SLAC-PUB-13428
hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We identify an invariant light-front coordinate $\zeta$ which allows the separation of the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single-variable light-front Schrodinger equation for QCD which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. This frame-independent light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-$J$ modes on anti-de Sitter (AdS) space. Light-front holography is a remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. In principle, the model can be systematically improved by diagonalizing the full QCD light-front Hamiltonian on the AdS/QCD basis. Quark and gluon hadronization can be computed at the amplitude level by convoluting the off-shell $T$ matrix calculated from the QCD light-front Hamiltonian with the hadronic light-front wavefunctions. We also note the distinction between static observables such as the probability distributions computed from the square of the light-front wavefunctions versus dynamical observables such as the structure functions and the leading-twist single-spin asymmetries measured in deep inelastic scattering which include the effects of initial and final-state interactions.
[ { "created": "Fri, 10 Oct 2008 02:45:58 GMT", "version": "v1" } ]
2008-10-13
[ [ "Brodsky", "Stanley J.", "" ], [ "de Teramond", "Guy F.", "" ] ]
We identify an invariant light-front coordinate $\zeta$ which allows the separation of the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single-variable light-front Schrodinger equation for QCD which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. This frame-independent light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-$J$ modes on anti-de Sitter (AdS) space. Light-front holography is a remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. In principle, the model can be systematically improved by diagonalizing the full QCD light-front Hamiltonian on the AdS/QCD basis. Quark and gluon hadronization can be computed at the amplitude level by convoluting the off-shell $T$ matrix calculated from the QCD light-front Hamiltonian with the hadronic light-front wavefunctions. We also note the distinction between static observables such as the probability distributions computed from the square of the light-front wavefunctions versus dynamical observables such as the structure functions and the leading-twist single-spin asymmetries measured in deep inelastic scattering which include the effects of initial and final-state interactions.
hep-ph/9609433
Mike Boyce
M. M. Boyce
String Inspired QCD and $E_6$ Models
173 pages, LaTeX, 49 figures (eps)
null
null
null
hep-ph nucl-th
null
The work in this thesis consists of two distinct parts: A class of models called, ``String-flip potential models,'' (SFP's) are studied as a possible candidate for modeling nuclear matter in terms of constituent quarks. These models are inspired from lattice quantum-chromodynamics (QCD) and are nonperturbative in nature. It is shown that they are viable candidates for modeling nuclear matter since they reproduce most of the bulk properties except for nuclear binding. Their properties are studied in nuclear and mesonic matter. A new class of models is developed, called ``flux-bubble potential models,'' which allows for the SFP's to be extended to include perturbative QCD interactions. Attempts to obtain nuclear binding is not successful, but valuable insight was gained towards possible future directions to pursue. The possibility of studying Superstring inspired $E_6$ phenomenology at high energy hadron colliders is investigated. The production of heavy lepton pairs {\it via} a gluon-gluon fusion mechanism is discussed. An enhancement in the parton level cross-section is expected due to the heavy (s)fermion loops which couple to the gluons.
[ { "created": "Mon, 23 Sep 1996 02:50:55 GMT", "version": "v1" } ]
2007-05-23
[ [ "Boyce", "M. M.", "" ] ]
The work in this thesis consists of two distinct parts: A class of models called, ``String-flip potential models,'' (SFP's) are studied as a possible candidate for modeling nuclear matter in terms of constituent quarks. These models are inspired from lattice quantum-chromodynamics (QCD) and are nonperturbative in nature. It is shown that they are viable candidates for modeling nuclear matter since they reproduce most of the bulk properties except for nuclear binding. Their properties are studied in nuclear and mesonic matter. A new class of models is developed, called ``flux-bubble potential models,'' which allows for the SFP's to be extended to include perturbative QCD interactions. Attempts to obtain nuclear binding is not successful, but valuable insight was gained towards possible future directions to pursue. The possibility of studying Superstring inspired $E_6$ phenomenology at high energy hadron colliders is investigated. The production of heavy lepton pairs {\it via} a gluon-gluon fusion mechanism is discussed. An enhancement in the parton level cross-section is expected due to the heavy (s)fermion loops which couple to the gluons.
hep-ph/9912498
Masahiro Yamaguchi
Sanghyeon Chang, Junji Hisano, Hiroaki Nakano, Nobuchika Okada, and Masahiro Yamaguchi
Bulk Standard Model in the Randall-Sundrum Background
18 pages, 2 figures
Phys.Rev. D62 (2000) 084025
10.1103/PhysRevD.62.084025
TU-581, KEK-TH-665, NIIG-DP-99-03
hep-ph hep-th
null
We discuss issues in an attempt to put the Standard Model (SM) in five-dimensional anti-de Sitter spacetime compactified on $S^1/Z_2$. The recently-proposed approach to the gauge hierarchy problem by using this background geometry, with the SM confined on a boundary, is extended to a situation where (some of) the SM particles reside in the five dimensional bulk. In particular, we find a localization of zero modes of bulk fermions near the boundary with a negative tension. Unlike the compactification with the flat metric, these fermion zero modes couple to Kaluza-Klein (KK) excitations of the SM gauge bosons. Interestingly, only low-lying modes of such KK gauge bosons have non-negligible couplings. Current electroweak precision data give a constraint that the first KK mode be heavier than 9 TeV. We also argue that at least the Higgs field should be confined on the brane to utilize the Randall-Sundrum background as a solution to the gauge hierarchy.
[ { "created": "Fri, 24 Dec 1999 07:22:35 GMT", "version": "v1" } ]
2009-10-31
[ [ "Chang", "Sanghyeon", "" ], [ "Hisano", "Junji", "" ], [ "Nakano", "Hiroaki", "" ], [ "Okada", "Nobuchika", "" ], [ "Yamaguchi", "Masahiro", "" ] ]
We discuss issues in an attempt to put the Standard Model (SM) in five-dimensional anti-de Sitter spacetime compactified on $S^1/Z_2$. The recently-proposed approach to the gauge hierarchy problem by using this background geometry, with the SM confined on a boundary, is extended to a situation where (some of) the SM particles reside in the five dimensional bulk. In particular, we find a localization of zero modes of bulk fermions near the boundary with a negative tension. Unlike the compactification with the flat metric, these fermion zero modes couple to Kaluza-Klein (KK) excitations of the SM gauge bosons. Interestingly, only low-lying modes of such KK gauge bosons have non-negligible couplings. Current electroweak precision data give a constraint that the first KK mode be heavier than 9 TeV. We also argue that at least the Higgs field should be confined on the brane to utilize the Randall-Sundrum background as a solution to the gauge hierarchy.
0709.4060
Yasunori Nomura
Yasunori Nomura and Michele Papucci
A Simple and Realistic Model of Supersymmetry Breaking
19 pages, version to appear in Phys. Lett. B
Phys.Lett.B661:145-153,2008
10.1016/j.physletb.2008.01.052
UCB-PTH-07/18
hep-ph hep-th
null
We present a simple and realistic model of supersymmetry breaking. In addition to the minimal supersymmetric standard model, we only introduce a hidden sector gauge group SU(5) and three fields X, F and \bar{F}. Supersymmetry is broken at a local minimum of the potential, and its effects are transmitted to the supersymmetric standard model sector through both standard model gauge loops and local operators suppressed by the cutoff scale, which is taken to be the unification scale. The form of the local operators is controlled by a U(1) symmetry. The generated supersymmetry breaking and mu parameters are comparable in size, and no flavor or CP violating terms arise. The spectrum of the first two generation superparticles is that of minimal gauge mediation with the number of messengers N_mess = 5 and the messenger scale 10^11 GeV < M_mess < 10^13 GeV. The spectrum of the Higgs bosons and third generation superparticles, however, can deviate from it. The lightest supersymmetric particle is the gravitino with a mass of order (1-10) GeV.
[ { "created": "Tue, 25 Sep 2007 23:18:10 GMT", "version": "v1" }, { "created": "Wed, 13 Feb 2008 18:47:12 GMT", "version": "v2" } ]
2008-11-26
[ [ "Nomura", "Yasunori", "" ], [ "Papucci", "Michele", "" ] ]
We present a simple and realistic model of supersymmetry breaking. In addition to the minimal supersymmetric standard model, we only introduce a hidden sector gauge group SU(5) and three fields X, F and \bar{F}. Supersymmetry is broken at a local minimum of the potential, and its effects are transmitted to the supersymmetric standard model sector through both standard model gauge loops and local operators suppressed by the cutoff scale, which is taken to be the unification scale. The form of the local operators is controlled by a U(1) symmetry. The generated supersymmetry breaking and mu parameters are comparable in size, and no flavor or CP violating terms arise. The spectrum of the first two generation superparticles is that of minimal gauge mediation with the number of messengers N_mess = 5 and the messenger scale 10^11 GeV < M_mess < 10^13 GeV. The spectrum of the Higgs bosons and third generation superparticles, however, can deviate from it. The lightest supersymmetric particle is the gravitino with a mass of order (1-10) GeV.
0801.1802
Thorsten Feldmann
Thorsten Feldmann (TU Munich and Univ. Siegen), Thomas Mannel (Univ. Siegen)
Large Top Mass and Non-Linear Representation of Flavour Symmetry
4 pages, no figures, uses revtex4
Phys.Rev.Lett.100:171601,2008
10.1103/PhysRevLett.100.171601
SI-HEP-2008-01, TUM-HEP-680/08
hep-ph hep-th
null
We consider an effective theory (ET) approach to flavour-violating processes beyond the Standard Model (SM), where the breaking of flavour symmetry is described by spurion fields whose low-energy vacuum expectation values are identified with the SM Yukawa couplings. Insisting on canonical mass dimensions for the spurion fields, the large top-quark Yukawa coupling also implies a large expectation value for the associated spurion, which breaks part of the flavour symmetry already at the UV scale Lambda of the ET. Below that scale, flavour symmetry in the ET is represented in a non-linear way by introducing Goldstone modes for the partly broken flavour symmetry and spurion fields transforming under the residual symmetry. As a result, the dominance of certain flavour structures in rare quark decays can be understood in terms of the 1/Lambda expansion in the ET. We also discuss the generalization to 2-Higgs-doublet models with large tan(beta).
[ { "created": "Fri, 11 Jan 2008 16:30:17 GMT", "version": "v1" } ]
2008-11-26
[ [ "Feldmann", "Thorsten", "", "TU Munich and Univ. Siegen" ], [ "Mannel", "Thomas", "", "Univ.\n Siegen" ] ]
We consider an effective theory (ET) approach to flavour-violating processes beyond the Standard Model (SM), where the breaking of flavour symmetry is described by spurion fields whose low-energy vacuum expectation values are identified with the SM Yukawa couplings. Insisting on canonical mass dimensions for the spurion fields, the large top-quark Yukawa coupling also implies a large expectation value for the associated spurion, which breaks part of the flavour symmetry already at the UV scale Lambda of the ET. Below that scale, flavour symmetry in the ET is represented in a non-linear way by introducing Goldstone modes for the partly broken flavour symmetry and spurion fields transforming under the residual symmetry. As a result, the dominance of certain flavour structures in rare quark decays can be understood in terms of the 1/Lambda expansion in the ET. We also discuss the generalization to 2-Higgs-doublet models with large tan(beta).
hep-ph/9708477
Erhan Iltan
G. Hiller (DESY, Hamburg) and E. O. Iltan (METU, Ankara)
Estimate of the long-distance contribution through b --> s \psi to the B_{s} --> \gamma\gamma decay rate
10 pages, 1 figure (require epsf.sty)
Mod.Phys.Lett.A12:2837-2846,1997
10.1142/S021773239700296X
null
hep-ph
null
The B_{s} --> \phi\psi decay is modeled through the inclusive b --> s\psi decay. Using the Vector Meson Dominance model, the amplitude for the chain process B_{s} --> \phi\psi --> \phi\gamma --> \gamma\gamma is estimated and it is found to be at most 4 % of the corresponding amplitude from the O_7 type LD contribution. The intermediate amplitude for the process B_{s} --> \phi\gamma is compared with the corresponding one obtained by a different approach based on the interaction of the virtual charm quark loop with soft gluons \cite{Ruckl}. Both amplitudes are found to agree within 10 %. Further the influence on the branching ratio B(B_{s} --> \gamma\gamma)_{SD+LD_{O7}} from inclusive b --> s \psi is estimated as less than 1 %.
[ { "created": "Wed, 27 Aug 1997 16:05:14 GMT", "version": "v1" } ]
2011-07-19
[ [ "Hiller", "G.", "", "DESY, Hamburg" ], [ "Iltan", "E. O.", "", "METU, Ankara" ] ]
The B_{s} --> \phi\psi decay is modeled through the inclusive b --> s\psi decay. Using the Vector Meson Dominance model, the amplitude for the chain process B_{s} --> \phi\psi --> \phi\gamma --> \gamma\gamma is estimated and it is found to be at most 4 % of the corresponding amplitude from the O_7 type LD contribution. The intermediate amplitude for the process B_{s} --> \phi\gamma is compared with the corresponding one obtained by a different approach based on the interaction of the virtual charm quark loop with soft gluons \cite{Ruckl}. Both amplitudes are found to agree within 10 %. Further the influence on the branching ratio B(B_{s} --> \gamma\gamma)_{SD+LD_{O7}} from inclusive b --> s \psi is estimated as less than 1 %.
2311.06636
Sergey Godunov
S. I. Godunov, E. K. Karkaryan, V. A. Novikov, A. N. Rozanov, M. I. Vysotsky, E. V. Zhemchugov
On production of heavy charged particles in $\gamma\gamma$ fusion at planned $pp$ colliders
8 pages, 4 figures, 2 tables
null
null
null
hep-ph hep-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Production of heavy fermions in ultraperipheral collisions ($pp\to p+\gamma\gamma+p\to p+\chi^{+}\chi^{-}+p$) and the semiexclusive reaction ($pp \to p+\gamma\gamma^{*}+X \to p+\chi^{+}\chi^{-}+X$) is considered. Differential and total cross sections for the energies of the planned $pp$ colliders are presented.
[ { "created": "Sat, 11 Nov 2023 18:33:20 GMT", "version": "v1" } ]
2023-11-14
[ [ "Godunov", "S. I.", "" ], [ "Karkaryan", "E. K.", "" ], [ "Novikov", "V. A.", "" ], [ "Rozanov", "A. N.", "" ], [ "Vysotsky", "M. I.", "" ], [ "Zhemchugov", "E. V.", "" ] ]
Production of heavy fermions in ultraperipheral collisions ($pp\to p+\gamma\gamma+p\to p+\chi^{+}\chi^{-}+p$) and the semiexclusive reaction ($pp \to p+\gamma\gamma^{*}+X \to p+\chi^{+}\chi^{-}+X$) is considered. Differential and total cross sections for the energies of the planned $pp$ colliders are presented.
1204.4389
Yibiao Chen
Yibiao Chen and Pengfei Zhuang
Dimuonium $(\mu^+\mu^-)$ Production in a Quark-Gluon Plasma
4 pages, 3 figures
null
null
null
hep-ph nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study dimuonium $(\mu^+\mu^-)$ production in the quark-gluon plasma created in relativistic heavy ion collisions. The production is controlled by the process $q\bar q\rightarrow (\mu^+\mu^-)g$, and the dimuonium motion in the plasma is described by a transport equation. While the electrodynamics dominated dimuonium yield is not high enough, the transverse energy distribution carries the information of the plasma at RHIC and LHC energies.
[ { "created": "Thu, 19 Apr 2012 15:53:52 GMT", "version": "v1" }, { "created": "Mon, 23 Apr 2012 07:34:22 GMT", "version": "v2" } ]
2012-04-24
[ [ "Chen", "Yibiao", "" ], [ "Zhuang", "Pengfei", "" ] ]
We study dimuonium $(\mu^+\mu^-)$ production in the quark-gluon plasma created in relativistic heavy ion collisions. The production is controlled by the process $q\bar q\rightarrow (\mu^+\mu^-)g$, and the dimuonium motion in the plasma is described by a transport equation. While the electrodynamics dominated dimuonium yield is not high enough, the transverse energy distribution carries the information of the plasma at RHIC and LHC energies.
1604.06446
Alessandro Strumia
Roberto Franceschini, Gian F. Giudice, Jernej F. Kamenik, Matthew McCullough, Francesco Riva, Alessandro Strumia, Riccardo Torre
Digamma, what next?
53 pages, 21 figures. v2: references added
null
10.1007/JHEP07(2016)150
CERN-TH-2016-090
hep-ph hep-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
If the 750 GeV resonance in the diphoton channel is confirmed, what are the measurements necessary to infer the properties of the new particle and understand its nature? We address this question in the framework of a single new scalar particle, called digamma ($\digamma$). We describe it by an effective field theory, which allows us to obtain general and model-independent results, and to identify the most useful observables, whose relevance will remain also in model-by-model analyses. We derive full expressions for the leading-order processes and compute rates for higher-order decays, digamma production in association with jets, gauge or Higgs bosons, and digamma pair production. We illustrate how measurements of these higher-order processes can be used to extract couplings, quantum numbers, and properties of the new particle.
[ { "created": "Thu, 21 Apr 2016 19:57:24 GMT", "version": "v1" }, { "created": "Wed, 11 May 2016 16:33:15 GMT", "version": "v2" } ]
2016-08-24
[ [ "Franceschini", "Roberto", "" ], [ "Giudice", "Gian F.", "" ], [ "Kamenik", "Jernej F.", "" ], [ "McCullough", "Matthew", "" ], [ "Riva", "Francesco", "" ], [ "Strumia", "Alessandro", "" ], [ "Torre", "Riccardo...
If the 750 GeV resonance in the diphoton channel is confirmed, what are the measurements necessary to infer the properties of the new particle and understand its nature? We address this question in the framework of a single new scalar particle, called digamma ($\digamma$). We describe it by an effective field theory, which allows us to obtain general and model-independent results, and to identify the most useful observables, whose relevance will remain also in model-by-model analyses. We derive full expressions for the leading-order processes and compute rates for higher-order decays, digamma production in association with jets, gauge or Higgs bosons, and digamma pair production. We illustrate how measurements of these higher-order processes can be used to extract couplings, quantum numbers, and properties of the new particle.
hep-ph/0510316
Anna-Zuzana Dubnickova
C. Adamuscin, S. Dubnicka, A.Z. Dubnickova, P. Weisenpacher
Unitary and analytic model of nucleon EM structure, the puzzle with JLab proton polarization data and new insight into proton charge distribution
9 pages, 11 eps figures. Talk presented at the workshop on Lepton Scattering and the Structure of Hadrons and Nuclei, Erice (Italy), September 2004
Prog.Part.Nucl.Phys.55:228-241,2005
10.1016/j.ppnp.2005.01.017
null
hep-ph
null
The Unitary and analytic model of nucleon electromagnetic structure, describing all existing nucleon form factor data, is briefly reviewed. Then in the framework of this model the problem of inconsistency of older proton electric form factor data in space-like region (obtained from $% e^{-}p\to e^{-}p$ process by the Rosenbluth technique) with recent Jefferson Lab data on the ratio $G_{Ep}(t)/G_{Mp}(t)$ (measured in precise polarization $\overrightarrow{e}^{-}p\to e^{-}\overrightarrow{p}$ experiment) is suggested to be solved in favour of the latter data which, however, unlike older data cause an existence of the form factor zero, i.e. a difraction minimum in $|G_{Ep}(t)|$ around $t=-Q^{2}=-13$GeV$^{2}$. The new behaviour of $G_{Ep}(t)$ with the zero gives modified proton charge distribution with enlarged value of the mean square charge radius.
[ { "created": "Mon, 24 Oct 2005 09:57:03 GMT", "version": "v1" } ]
2011-08-17
[ [ "Adamuscin", "C.", "" ], [ "Dubnicka", "S.", "" ], [ "Dubnickova", "A. Z.", "" ], [ "Weisenpacher", "P.", "" ] ]
The Unitary and analytic model of nucleon electromagnetic structure, describing all existing nucleon form factor data, is briefly reviewed. Then in the framework of this model the problem of inconsistency of older proton electric form factor data in space-like region (obtained from $% e^{-}p\to e^{-}p$ process by the Rosenbluth technique) with recent Jefferson Lab data on the ratio $G_{Ep}(t)/G_{Mp}(t)$ (measured in precise polarization $\overrightarrow{e}^{-}p\to e^{-}\overrightarrow{p}$ experiment) is suggested to be solved in favour of the latter data which, however, unlike older data cause an existence of the form factor zero, i.e. a difraction minimum in $|G_{Ep}(t)|$ around $t=-Q^{2}=-13$GeV$^{2}$. The new behaviour of $G_{Ep}(t)$ with the zero gives modified proton charge distribution with enlarged value of the mean square charge radius.
2006.11944
Artur Ankowski
Artur M. Ankowski and Alexander Friedland
Assessing the accuracy of the GENIE event generator with electron-scattering data
22 pages, 20 figures, matches the published version
Phys. Rev. D 102, 053001 (2020)
10.1103/PhysRevD.102.053001
SLAC-PUB-17541
hep-ph hep-ex nucl-ex nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Precision neutrino oscillation experiments of the future---of which DUNE is a prime example---require reliable event generator tools. The 1--4 GeV energy regime, in which DUNE will operate, is marked by the transition from the low-energy nuclear physics domain to that of perturbative QCD, resulting in rich and highly complex physics. Given this complexity, it is important to establish a validation procedure capable of disentangling the physical processes and testing each of them individually. Here, we demonstrate the utility of this approach by benchmarking the GENIE generator, currently used by all Fermilab-based experiments, against a broad set of inclusive electron-scattering data. This comparison takes advantage of the fact that, while electron-nucleus and neutrino-nucleus processes share a lot of common physics, electron scattering gives one access to precisely known beam energies and scattering kinematics. Exploring the kinematic parameter range relevant to DUNE in this manner, we observe patterns of large discrepancies between the generator and data. These discrepancies are most prominent in the pion-producing regimes and are present not only in medium-sized nuclei, including argon, but also in deuterium and hydrogen targets, indicating mismodeled hadronic physics. Several directions for possible improvement are discussed.
[ { "created": "Sun, 21 Jun 2020 23:57:39 GMT", "version": "v1" }, { "created": "Fri, 4 Sep 2020 06:03:17 GMT", "version": "v2" } ]
2020-09-07
[ [ "Ankowski", "Artur M.", "" ], [ "Friedland", "Alexander", "" ] ]
Precision neutrino oscillation experiments of the future---of which DUNE is a prime example---require reliable event generator tools. The 1--4 GeV energy regime, in which DUNE will operate, is marked by the transition from the low-energy nuclear physics domain to that of perturbative QCD, resulting in rich and highly complex physics. Given this complexity, it is important to establish a validation procedure capable of disentangling the physical processes and testing each of them individually. Here, we demonstrate the utility of this approach by benchmarking the GENIE generator, currently used by all Fermilab-based experiments, against a broad set of inclusive electron-scattering data. This comparison takes advantage of the fact that, while electron-nucleus and neutrino-nucleus processes share a lot of common physics, electron scattering gives one access to precisely known beam energies and scattering kinematics. Exploring the kinematic parameter range relevant to DUNE in this manner, we observe patterns of large discrepancies between the generator and data. These discrepancies are most prominent in the pion-producing regimes and are present not only in medium-sized nuclei, including argon, but also in deuterium and hydrogen targets, indicating mismodeled hadronic physics. Several directions for possible improvement are discussed.
1411.0304
Jen-Chieh Peng
Jen-Chieh Peng
Transverse Spin Effects in Future Drell-Yan Experiments
7 pages, 4 figures, Proceedings for the "Transversity 2014" Workshop
null
10.1051/epjconf/20158501009
null
hep-ph nucl-ex
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We review the current status and future prospect for probing the transverse momentum dependent (TMD) parton distributions using the Drell-Yan process. We focus on the Boer-Mulders and Sivers functions, which are expected to undergo a sign-change from semi-inclusive deep-inelastic scattering (SIDIS) to Drell-Yan process. The constraints of existing Drell-Yan and SIDIS experiments on the signs of these functions are discussed. Future Drell-Yan measurements for the TMDs are also presented.
[ { "created": "Sun, 2 Nov 2014 19:43:57 GMT", "version": "v1" } ]
2015-06-23
[ [ "Peng", "Jen-Chieh", "" ] ]
We review the current status and future prospect for probing the transverse momentum dependent (TMD) parton distributions using the Drell-Yan process. We focus on the Boer-Mulders and Sivers functions, which are expected to undergo a sign-change from semi-inclusive deep-inelastic scattering (SIDIS) to Drell-Yan process. The constraints of existing Drell-Yan and SIDIS experiments on the signs of these functions are discussed. Future Drell-Yan measurements for the TMDs are also presented.
hep-ph/9701359
null
A. A. Pankov, N. Paver, C. Verzegnassi
Z' effects and anomalous gauge couplings at LC with polarization
22 pages LaTex, 6 figures available on request, revised version accepted for publication in Int. J. Mod. Phys. A
Int.J.Mod.Phys. A13 (1998) 1629-1650
10.1142/S0217751X98000718
null
hep-ph
null
We show that the availability of longitudinally polarized electron beams at a 500 GeV Linear Collider would allow, from an analysis of the reaction e^+e^-\to W^+W^-, to set stringent bounds on the couplings of a Z' of the most general type. In addition, to some extent, it would be possible to disentangle observable effects of the Z' from analogous ones due to competitor models with anomalous trilinear gauge couplings.
[ { "created": "Thu, 23 Jan 1997 18:38:18 GMT", "version": "v1" }, { "created": "Wed, 25 Jun 1997 19:45:20 GMT", "version": "v2" } ]
2009-10-30
[ [ "Pankov", "A. A.", "" ], [ "Paver", "N.", "" ], [ "Verzegnassi", "C.", "" ] ]
We show that the availability of longitudinally polarized electron beams at a 500 GeV Linear Collider would allow, from an analysis of the reaction e^+e^-\to W^+W^-, to set stringent bounds on the couplings of a Z' of the most general type. In addition, to some extent, it would be possible to disentangle observable effects of the Z' from analogous ones due to competitor models with anomalous trilinear gauge couplings.
hep-ph/9601215
null
Wing Kai Wong (SLAC)
Renormalization Scale Setting for Evolution Equation of Non-Singlet Structure Functions and Their Moments
15 pages, RevTeX
Phys.Rev. D54 (1996) 1094-1098
10.1103/PhysRevD.54.1094
SLAC-PUB-95-7063
hep-ph
null
We use the BLM procedure to eliminate the renormalization scale ambiguity in the evolution equation for the non-singlet deep-inelastic structure function $F_2^{\text NS}(x,Q).$ The scale of the QCD coupling in the $\overline{\text{MS}}$ scheme has the form $Q^*(x) = Q (1-x)^{1/2} / x~f(x) $, where $x$ is the Bjorken variable and $f(x)$ is a smoothly varying function bounded between 0.30 to 0.45. Equivalently, the evolution of the $n$th moment of the structure function should contain an effective $\Lambda_{\text{QCD}}$ pattern, with $\Lambda_n \sim n^{1/2}$. This variation of $\Lambda_n$ agrees with experimental data.
[ { "created": "Fri, 5 Jan 1996 03:11:34 GMT", "version": "v1" } ]
2009-10-28
[ [ "Wong", "Wing Kai", "", "SLAC" ] ]
We use the BLM procedure to eliminate the renormalization scale ambiguity in the evolution equation for the non-singlet deep-inelastic structure function $F_2^{\text NS}(x,Q).$ The scale of the QCD coupling in the $\overline{\text{MS}}$ scheme has the form $Q^*(x) = Q (1-x)^{1/2} / x~f(x) $, where $x$ is the Bjorken variable and $f(x)$ is a smoothly varying function bounded between 0.30 to 0.45. Equivalently, the evolution of the $n$th moment of the structure function should contain an effective $\Lambda_{\text{QCD}}$ pattern, with $\Lambda_n \sim n^{1/2}$. This variation of $\Lambda_n$ agrees with experimental data.
hep-ph/9806472
L. C. R. Wijewardhana
Thomas Appelquist, Anuradha Ratnaweera, John Terning, L. C. R. Wijewardhana
The Phase Structure of an SU(N) Gauge Theory with N_f Flavors
34 pages, 1 figure. More references added
Phys.Rev.D58:105017,1998
10.1103/PhysRevD.58.105017
YCTP-P15-98, UCB-PTH-98/34, LBNL-41946,UCTP-110-98
hep-ph hep-th
null
We investigate the chiral phase transition in SU(N) gauge theories as the number of quark flavors, $N_f$, is varied. We argue that the transition takes place at a large enough value of $N_f$ so that it is governed by the infrared fixed point of the $\beta$ function. We study the nature of the phase transition analytically and numerically, and discuss the spectrum of the theory as the critical value of $N_f$ is approached in both the symmetric and broken phases. Since the transition is governed by a conformal fixed point, there are no light excitations on the symmetric side. We extend previous work to include higher order effects by developing a renormalization group estimate of the critical coupling.
[ { "created": "Wed, 24 Jun 1998 18:51:38 GMT", "version": "v1" }, { "created": "Wed, 26 Aug 1998 22:11:04 GMT", "version": "v2" } ]
2014-11-17
[ [ "Appelquist", "Thomas", "" ], [ "Ratnaweera", "Anuradha", "" ], [ "Terning", "John", "" ], [ "Wijewardhana", "L. C. R.", "" ] ]
We investigate the chiral phase transition in SU(N) gauge theories as the number of quark flavors, $N_f$, is varied. We argue that the transition takes place at a large enough value of $N_f$ so that it is governed by the infrared fixed point of the $\beta$ function. We study the nature of the phase transition analytically and numerically, and discuss the spectrum of the theory as the critical value of $N_f$ is approached in both the symmetric and broken phases. Since the transition is governed by a conformal fixed point, there are no light excitations on the symmetric side. We extend previous work to include higher order effects by developing a renormalization group estimate of the critical coupling.
hep-ph/0008114
Joannis Papavassiliou
J. Bernabeu, L. G. Cabral-Rosetti, J. Papavassiliou, J. Vidal
On the charge radius of the neutrino
26 pages, plain Latex, 7 Figures in a separate ps file
Phys.Rev.D62:113012,2000
10.1103/PhysRevD.62.113012
null
hep-ph
null
Using the pinch technique we construct at one-loop order a neutrino charge radius, which is finite, depends neither on the gauge-fixing parameter nor on the gauge-fixing scheme employed, and is process-independent. This definition stems solely from an effective proper photon-neutrino one-loop vertex, with no reference to box or self-energy contributions. The role of the $WW$ box in this construction is critically examined. In particular it is shown that the exclusion of the effective WW box from the definition of the neutrino charge radius is not a matter of convention but is in fact dynamically realized when the target-fermions are right-handedly polarized. In this way we obtain a unique decomposition of effective self-energies, vertices, and boxes, which separately respect electroweak gauge invariance. We elaborate on the tree-level origin of the mechanism which enforces at one-loop level massive cancellations among the longitudinal momenta appearing in the Feynman diagrams, and in particular those associated with the non-abelian character of the theory. Various issues related to the known connection between the pinch technique and the Background Field Method are further clarified. Explicit closed expressions for the neutrino charge radius are reported.
[ { "created": "Fri, 11 Aug 2000 16:05:09 GMT", "version": "v1" } ]
2008-11-26
[ [ "Bernabeu", "J.", "" ], [ "Cabral-Rosetti", "L. G.", "" ], [ "Papavassiliou", "J.", "" ], [ "Vidal", "J.", "" ] ]
Using the pinch technique we construct at one-loop order a neutrino charge radius, which is finite, depends neither on the gauge-fixing parameter nor on the gauge-fixing scheme employed, and is process-independent. This definition stems solely from an effective proper photon-neutrino one-loop vertex, with no reference to box or self-energy contributions. The role of the $WW$ box in this construction is critically examined. In particular it is shown that the exclusion of the effective WW box from the definition of the neutrino charge radius is not a matter of convention but is in fact dynamically realized when the target-fermions are right-handedly polarized. In this way we obtain a unique decomposition of effective self-energies, vertices, and boxes, which separately respect electroweak gauge invariance. We elaborate on the tree-level origin of the mechanism which enforces at one-loop level massive cancellations among the longitudinal momenta appearing in the Feynman diagrams, and in particular those associated with the non-abelian character of the theory. Various issues related to the known connection between the pinch technique and the Background Field Method are further clarified. Explicit closed expressions for the neutrino charge radius are reported.