publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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1995-01-26 | From Spectroscopy to the Strong Coupling Constant with Heavy Wilson Quarks | In this work we present lattice calculations of the masses of P-wave mesons
using Monte Carlo simulations. Our valence fermions are defined by the Wilson
action. Our gauge fields are generated with both dynamical staggered fermions
at a lattice coupling $\beta\equiv 6/g^2=5.6$ for sea quark masses of
$am_q=0.010$ and 0... | 9501034v1 |
1995-02-06 | Scaling behavior of the four-point renormalized coupling constant in the two dimensional O(2) and O(3) non-linear sigma models | We report thermodynamic values of four-point renormalized coupling constant
calculated by Monte Carlo simulations in the continuum limits of the lattice
versions of the two-dimensional O(2) and O(3) non-linear sigma models. In each
case the critical index of the coupling constant vanishes, which leads to
hyperscaling (... | 9502005v1 |
1995-08-31 | The Hierarchical $φ^4$ - Trajectory by Perturbation Theory in a Running Coupling and its Logarithm | We compute the hierarchical $\phi^4$-trajectory in terms of perturbation
theory in a running coupling. In the three dimensional case we resolve a
singularity due to resonance of power counting factors in terms of logarithms
of the running coupling. Numerical data is presented and the limits of validity
explored. We als... | 9508031v2 |
1995-09-12 | Strong-coupling expansion of lattice O(N) sigma models | We report progress in the computation and analysis of strong-coupling series
of two- and three-dimensional ${\rm O}(N)$ $\sigma$ models. We show that,
through a combination of long strong-coupling series and judicious choice of
observables, one can compute continuum quantities reliably and with a precision
at least com... | 9509025v1 |
1995-10-09 | The Phase Structure of the Schwinger Model on the Lattice with Wilson Fermions in the Hartree-Fock Approximation | The phase diagram of the Schwinger model on the lattice with one and two
degenerate flavours of Wilson fermions is investigated in the Hartree-Fock
approximation. In case of a single flavour (not directly amenable to numerical
simulation), the calculation indicates the existence of the parity violating
phase at both we... | 9510018v1 |
1995-10-24 | The Strong Coupling Constant from the Lattice 3-Gluon Vertex | We compute the QCD running coupling on the lattice as defined from the
3-gluon vertex. We present the results of an exploratory study at $\beta=6.0$
on a $16^4$ lattice, which show that for momenta larger than 2 \Gev, the
coupling runs according to the 2-loop asymptotic formula, allowing a precise
determination of the ... | 9510045v1 |
1996-05-03 | A Lattice Chiral Theory with Multifermion Couplings | Analyzing an $SU_L(2)\otimes U_R(1)$ chiral theory with multifermion
couplings on a lattice, we find a possible region in the phase space of
multifermion couplings, where no spontaneous symmetry breaking occurs, doublers
are decoupled as massive Dirac fermions consistently with the $SU_L(2)\otimes
U_R(1)$ chiral symmet... | 9605003v1 |
1996-08-29 | Scaling Structures in Four-dimensional Simplicial Gravity | Four-dimensional(4D) spacetime structures are investigated using the concept
of the geodesic distance in the simplicial quantum gravity. On the analogy of
the loop length distribution in 2D case, the scaling relations of the boundary
volume distribution in 4D are discussed in various coupling regions i.e.
strong-coupli... | 9608149v2 |
1997-04-07 | Running coupling constant of background perturbation theory and lattice interquark interaction | The conventional parametrizations of lattice static interquark force are
shown to produce a mismatch of coupling constant near the matching point R_m
\approx 0.2 fm. The running coupling constant of the background perturbation
theory yields instead a selfconsistent description of lattice data over all
interval of dista... | 9704004v1 |
1997-05-08 | The Schrödinger functional running coupling with staggered fermions | We discuss the Schr\"odinger functional in lattice QCD with staggered
fermions including its order $O(a)$ boundary counterterms. We relate it, in the
classical continuum limit, to the Schr\"odinger functional as obtained in the
same limit with Wilson fermions. We compute the strong coupling constant
defined via the Sch... | 9705012v1 |
1997-09-10 | Monopole percolation in scalar QED | Monopole Percolation was first introduced in the study of the non-compact
lattice QED in both, the pure case and coupled to Higgs fields. Monopole
percolation has been also observed coupled to the monopole condensation in the
study of the pure gauge compact QED. We present here the results coming from
the analysis of t... | 9709023v1 |
1998-05-13 | Application of the Coupled Cluster Method to a Hamiltonian Lattice Field Theory | The coupled cluster method has been applied to the eigenvalue problem lattice
Hamiltonian QCD (without quarks) for SU(2) gauge fields in two space
dimensions.
Using a recently presented new formulation and the truncation prescription of
Guo et al. we were able to compute the ground state and the lowest
$0^+$-glueball... | 9805011v1 |
1998-10-08 | Numerical Study of the Gluon Propagator in Lattice Landau Gauge: the Three-Dimensional Case | We study the infrared behavior of the gluon propagator in lattice Landau
gauge, for pure SU(2) lattice gauge theory in a three-dimensional lattice.
Simulations are done for nine different values of the coupling $\beta$, from
$\beta = 0$ (strong coupling) to $\beta = 6.0$ (in the weak-coupling region).
In the limit of l... | 9810022v1 |
1999-07-15 | Running coupling for Wilson bermions | A non perturbative finite size scaling technique is used to study a running
coupling in lattice Yang-Mills theory coupled to a bosonic Wilson spinor field
in the Schr\"odinger functional scheme. This corresponds to two negative
flavours. The scaling behaviour in this case is compared to quenched results
and to QCD with... | 9907007v1 |
1999-07-30 | Abelian gauge fields coupled to simplicial quantum gravity | We study the coupling of Abelian gauge theories to four-dimensional
simplicial quantum gravity. The gauge fields live on dual links. This is the
correct formulation if we want to compare the effect of gauge fields on
geometry with similar effects studied so far for scalar fields. It shows that
gauge fields couple equal... | 9907027v2 |
1999-10-01 | The Weak-Coupling Limit of 3D Simplicial Quantum Gravity | We investigate the weak-coupling limit, kappa going to infinity, of 3D
simplicial gravity using Monte Carlo simulations and a Strong Coupling
Expansion. With a suitable modification of the measure we observe a transition
from a branched polymer to a crinkled phase. However, the intrinsic geometry of
the latter appears ... | 9910003v1 |
2000-01-12 | Chiral Symmetry Breaking in Strongly Coupled 1+1 Dimensional Lattice Gauge Theories | We analyse - within the hamiltonian formalism with staggered fermions - the
patterns of chiral symmetry breaking for the strongly coupled Schwinger and
$U({\cal N}_c)$-color `t Hooft models with one and two flavor of fermions.
Using the correspondence between these strongly coupled gauge models and
antiferromagnetic sp... | 0001012v1 |
2000-01-27 | Pions in Lattice QCD with the Overlap Fermions at Strong Gauge Coupling | In the previous paper we developed a strong-coupling expansion for the
lattice QCD with the overlap fermions and showed that L\"usher's "extended"
chiral symmetry is spontaneously broken in some parameter region of the overlap
fermions. In this paper, we obtain a low-energy effective action and show that
there exist qu... | 0001030v1 |
2001-03-15 | The Weakly Coupled Gross-Neveu Model with Wilson Fermions | The nature of the phase transition in the lattice Gross-Neveu model with
Wilson fermions is investigated using a new analytical technique. This involves
a new type of weak coupling expansion which focuses on the partition function
zeroes of the model. Its application to the single flavour Gross-Neveu model
yields a pha... | 0103014v1 |
2003-04-21 | A perturbative determination of O(a) boundary improvement coefficients for the Schrödinger Functional coupling at 1-loop with improved gauge actions | We determine O($a$) boundary improvement coefficients up to 1-loop level for
the Schr\"odinger Functional coupling with improved gauge actions including
plaquette and rectangle loops. These coefficients are required to implement
1-loop O($a$) improvement in full QCD simulations for the coupling with the
improved gauge ... | 0304013v1 |
2003-08-20 | Naturally Light Fermions from Dimensional Reduction | We consider the 3-d Gross-Neveu model in the broken phase and construct a
stable brane world by means of a domain wall and an anti-wall. Fermions of
opposite chirality are localized on the walls and coupled through the 3-d bulk.
At large wall separation \beta the 2-d correlation length diverges
exponentially, hence a 2... | 0308022v1 |
2003-09-25 | A perturbative determination of O($a$) boundary improvement coefficients for the Schrödinger Functional coupling at 1-loop with improved gauge actions | We perturbatively determine O($a$) boundary improvement coefficients at
1-loop for the Schr\"odinger Functional coupling with improved gauge actions.
These coefficients are required to implement the 1-loop O($a$) improvement in
full QCD simulations for the coupling with the improved gauge actions. To this
order, lattic... | 0309160v1 |
2003-11-04 | Triviality of hierarchical O(N) spin model in four dimensions with large N | The renormalization group transformation for the hierarchical O(N) spin model
in four dimensions is studied by means of characteristic functions of
single-site measures, and convergence of the critical trajectory to the
Gaussian fixed point is shown for a sufficiently large N. In the strong
coupling regime, the traject... | 0311005v1 |
2006-12-27 | Precision study of B^* Bπcoupling for the static heavy-light meson | We compute the B^*B\pi coupling \hat{g}_{\infty} for static heavy-light meson
using all-to-all propagators. It is shown that low-mode averaging with 100
low-lying eigenmodes indeed improves the signal for the 2-point and 3-point
functions for heavy-light meson significantly. Our study suggests that the
all-to-all propa... | 0612029v2 |
1992-05-27 | Anomalous Radiative Decay of Heavy Higgs Boson | The radiative decay width of a heavy Higgs boson $H \rightarrow W^+W^-\gamma$
for a {\it hard} photon is calculated in the Standard Model and its extension
with anomalous $\gamma WW$ couplings. Its dependence on the Higgs mass, the two
unknown anomalous couplings, and the photon energy cutoff are studied in
detail. We ... | 9205239v1 |
1992-06-03 | Analysis of Running Coupling Constant Unification in String Theory | We use recently obtained 2-loop string coupling constants to analyze a class
of string models based on orbifold compactification. Assuming weak coupling at
the string scale and single-scale unification leads to restrictions on the
spectrum of massive (between the string scale and the weak scale) matter
supermultiplets ... | 9206206v1 |
1992-06-22 | Finite Temperature Renormalization of the $(φ^3)_6$- and $(φ^4)_4$-Models at Zero Momentum | A self-consistent renormalization scheme at finite temperature and zero
momentum is used together with the finite temperature renormalization group to
study the temperature dependence of the mass and the coupling to one-loop order
in the $(\phi^3)_6$- and $(\phi^4)_4$-models. It is found that the critical
temperature i... | 9206240v1 |
1992-10-08 | Signatures for Heavy $\bf Z'$ Bosons at Hadron Colliders | We discuss three promising diagnostic probes of the couplings of a possible
heavy $Z'$ boson at hadron colliders: the forward-backward asymmetry into
leptons, the rare decay $Z' \ra W^{\pm} \ell^{\mp} \nu$, and associated
production $pp \ra Z'W,\; Z'Z$. A general model-independent framework is
proposed for interpreting... | 9210222v1 |
1992-10-14 | Uncertainties in Coupling Constant Unification | The status of coupling constant unification in the standard model and its
supersymmetric extension are discussed. Uncertainties associated with the input
coupling constants, $m_{t}$, threshold corrections at the low and high scales,
and possible nonrenormalizable operators are parametrized and estimated. A
simple param... | 9210235v1 |
1992-10-30 | On the High $T$ Phase Transition in the Gauged $SU(2)$ Higgs Model | We study the effective field theory of a weakly coupled 3+1d gauged $\phi^4$
type model at high temperature. Our model has $4N$ real scalars
($N$ complex Higgs doublets) and a gauge group $SU(2)$ which is spontaneously
broken by a nonzero scalar field $vev$ at zero temperature.
We find, for sufficiently large $N$, ... | 9210278v1 |
1993-02-15 | Coupling Constant Unification and LEP Data | The recent LEP data for gauge coupling constants constrain many grand unified
models. In this paper, we study several possibilities for unification of gauge
coupling constants. Without an intermediate mass scale, the minimal
supersymmetric standard model is the only possibility. For one intermediate
mass scale, it is p... | 9302260v1 |
1993-03-11 | Constraints from Nucleosynthesis and SN1987A on Majoron Emitting Double Beta Decay | We examine whether observable majoron emission in double beta decay can be
compatible with the big-bang nucleosynthesis (NS) and the observed neutrino
flux from SN1987A. It is found that the NS upper bound on $^4$He abundance
implies that the majoron-neutrino Yukawa coupling constant $g\leq 9\times
10^{-6}$ and its max... | 9303243v1 |
1993-03-18 | Electroweak Corrections to the Supersymmetric Charged Higgs Fermionic Decay | One-loop radiative corrections to the charged Higgs coupling to two fermions
and to the charged Higgs fermionic decay are studied. A renormalization scheme
is proposed including the definition of the parameter $\tan\beta$ through the
coupling of the CP-odd Higgs boson to a charged lepton pair. Loops including
top and b... | 9303279v1 |
1993-05-03 | Weak Coupling Phase Structureof the Abelian Higgs Model at Finite Temperature | Using the 1-loop reduced 3D action of the Abelian Higgs-model we discuss the
order of its finite temperature phase transition. A two-variable saddle point
approximation is proposed for the evaluation of the effective potential. The
strength of the first order case scales like \sim e^{3-6}. Analytic asymptotic
weak coup... | 9305201v1 |
1993-06-14 | Non-perturbative unification in the light of LEP results | We consider an alternative to conventional GUTs originally proposed by
Maiani, Parisi and Petronzio, where owing to the existence of extra fermion
generations at some intermediate scale, the gauge couplings become large at
high energies. We first comment on how the non- supersymmetric version of this
scenario is ruled ... | 9306269v1 |
1993-07-22 | Destabilizing Divergences in Supergravity-Coupled Supersymmetric Theories | Nonrenormalizable couplings in supergravity-coupled supersymmetric theories
can give rise to power-law divergences that destabilize the weak-scale
hierarchy. For the case of the standard-model gauge group, the problem can
arise in theories with \321 gauge-singlet chiral superfields. The minimal
supersymmetric standard ... | 9307317v5 |
1993-08-02 | Anomalous Gauge-Boson Couplings in High Energy ep Collisions | We investigate the sensitivity of total cross sections of $e+p \rightarrow
W,Z$ to CP-conserving non-standard $WW\gamma$ couplings. We include all the
important production mechanisms and study the dependence of the total $W$ cross
sections on the anomalous $WW\gamma$ couplings, $\kappa$ and $\lambda$. We
argue that the... | 9307377v1 |
1993-08-04 | Regularization Dependence of Running Couplings in Softly Broken Supersymmetry | We discuss the dependence of running couplings on the choice of
regularization method in a general softly-broken N=1 supersymmetric theory.
Regularization by dimensional reduction respects supersymmetry, but standard
dimensional regularization does not. We find expressions for the differences
between running couplings ... | 9308222v2 |
1993-08-04 | Loop-Induced Majoronic Decay of Neutrinos: | In models where the suppression of the tree level couplings of fermions with
Goldstone bosons is not protected by symmetry, the loop-induced couplings can
in general dominate over the tree couplings. We demonstrate this by calculating
the decay $\nu\to \nu' + \mbox{Majoron}$ in the simplest singlet Majoron model.
It is... | 9308224v1 |
1993-08-10 | Testing the handedness of a heavy $W^{\prime}$ at future hadron colliders | We show that the associated production $pp\to W^{\prime}W$, and the rare
decay $pp\to W'\to \bar\ell\ell W$ are useful tests of $W'$ couplings to
fermions at future hadron colliders. For $M_{W'}\sim (1 - 3)$ TeV they would
allow a clean determination on whether the $W'$ couples to $V-A$ or $V+A$
currents. As an illustr... | 9308251v1 |
1993-09-01 | Using `Invisible' Decay Modes as Probes of Z' Couplings | We explore the possibility that $Z'$ couplings can be probed using decay
modes which involve neutrinos once Standard Model backgrounds are directly
determined by the data itself. For some models, sufficient statistics are
available at either the SSC or LHC to render these modes useful for coupling
determinations, provi... | 9309207v1 |
1993-09-02 | Probing $WWγ$ Couplings from $σ_{tot}(W)/σ_{tot}(Z)$ in High Energy ep Collisions | We investigate the sensitivity of total cross sections of $e+p \rightarrow
W,Z$ to CP-conserving non-standard $WW\gamma$ couplings. We include all the
important production mechanisms and study the dependence of the total $W$ cross
sections on the anomalous $WW\gamma$ couplings, $\kappa$ and $\lambda$. We
argue that the... | 9309212v1 |
1993-09-06 | Constraints on the anomalous $WWγ$ couplings from $b\rightarrow sγ$ | We study contributions to $b \rightarrow s \gamma$ from anomalous $WW\gamma$
interactions. Although these anomalous interactions are not renormalizable, the
contributions are cut-off independent. Using recent results from the CLEO
collaboration on inclusive radiative B decays, we obtain bounds for the
anomalous CP cons... | 9309228v1 |
1993-11-08 | Soft Fields and Hard Particles in Hot Gauge Plasmas | It is shown that the long wavelength excitations of a quark-gluon plasma may
be described as collective oscillations of self-consistent average fields to
which the plasma particles couple. Their properties are obtained from a set of
coupled mean field and kinetic equations, derived from the general
Dyson-Schwinger equa... | 9311236v1 |
1993-11-09 | RGE Results for Supersymmetric GUTS | The scaling behavior of gauge couplings and fermion Yukawa couplings in the
minimal supersymmetric model is discussed. The relevance of the top quark
Yukawa coupling fixed point in establishing the top quark mass is described.
The evolution of mixing angles is presented. | 9311252v1 |
1993-12-23 | Complete Classes of GUTs with Vanishing One-Loop Beta Functions | By explicit solution of the one-loop finiteness conditions for all
dimensionless coupling constants (i.~e., gauge coupling constant as well as
Yukawa and quartic scalar-boson self-interaction coupling constants), two
classes of grand unified theories characterized by renormalization-group beta
functions which all vanis... | 9312335v1 |
1993-12-27 | Bounds on Vector Leptoquarks | We derive bounds on vector leptoquarks coupling to the first generation,
using data from low energy experiments as well as from high energy
accelerators. Similarly to the case of scalar leptoquarks, we find that the
strongest indirect bounds arise from atomic parity violation and universality
in leptonic pi decays. The... | 9312341v1 |
1994-01-17 | Couplings of heavy hadrons with soft pions from QCD sum rules | We estimate the couplings in the Heavy Hadron Chiral Theory (HHCT) lagrangian
from the QCD sum rules in an external axial field. Stability of the sum rules
at moderate values of the Borel parameter is poor that probably signals a slow
convergence of the OPE series. At large values of the Borel parameter they
stabilize,... | 9401267v1 |
1994-03-22 | Gauge Coupling Unification due to Non-universal Soft Supersymmetry Breaking | Gauge coupling unification is studied in the MSSM with non-universal soft
supersymmetry breaking terms. If gaugino masses are sufficiently smaller than
scalar soft masses and the scalar soft masses have also certain types of
non-universality, gauge coupling unification scale can be larger than $3\times
10^{16}$~GeV eve... | 9403330v1 |
1994-03-24 | Search for Anomalous Couplings at $eγ$ Colliders | We consider the possibility of observing deviations from the Standard Model
gauge-boson self-couplings at future $e\gamma$ colliders. We concentrate on the
process $e^-\gamma \rightarrow \nu W^- Z$, which is particularly sensitive to
the parity violating coupling $g_5^Z$ at high energies. We find that a 2~TeV
$e^+ e^-$... | 9403358v1 |
1994-03-28 | Massless Scalar QED with Non-minimal Chern Simons Coupling | 2+1 dimensional massless scalar QED with $(\phi^*\phi)^3$ scalar
self-coupling is modified by the addition of a non- minimal Chern-Simons term
that couples the dual of the electromagnetic field strength to the covariant
current of the complex scalar field. The theory is shown to be fully one- loop
renormalizable. The o... | 9403375v1 |
1994-05-03 | From Kondo Model and Strong Coupling Lattice QCD to the Isgur-Wise Function | Isgur-Wise functions parametrise the leading behaviour of weak decay form
factors of mesons and baryons containing a single heavy quark. The form factors
for the quark mass operator are calculated in strong coupling lattice QCD, and
Isgur-Wise functions extracted from them. Based on renormalisation group
invariance of ... | 9405213v1 |
1994-06-15 | Anomalous quartic couplings in $ W^+W^- γ$ production at $e^+e^- $ colliders | We study the process $e^+e^- \rightarrow W^+W^- \gamma$ at high-energy $e^+
e^-$ colliders to investigate the effect of genuine quartic
$W^+W^-\gamma\gamma$ and $W^+W^- Z\gamma$ anomalous couplings on the cross
section. Deviations from the Standard Model predictions are quantified. We show
how bounds on the anomalous c... | 9406317v1 |
1994-07-05 | New probes of anomalous $WWγ$ couplings at future $e^+e^-$ linacs | We investigate the sensitivity of single photon plus missing energy
cross-sections at future $e^{+}e^{-}$ linacs to non-standard $WW\gamma$
couplings. We show that even with conservative estimates of systematic errors
there is still considerable sensitivity to anomalous couplings. Analytic
expressions for helicity ampl... | 9407223v1 |
1994-07-21 | Gauge independent Chiral Symmetry Breaking in Quenched QED | In quenched QED we construct a non-perturbative fermion-boson vertex that
ensures the fermion propagator satisfies the Ward-Takahashi identity, is
multiplicatively renormalizable, agrees with perturbation theory for weak
couplings and has a critical coupling for dynamical mass generation that is
strictly gauge independ... | 9407350v2 |
1994-08-08 | Leptoquark Search at $e^+ e^-$ Colliders | We investigate the possibility of detecting a scalar leptoquark, coupling to
the electron and the top, at a linear collider. For coupling strength equalling
the weak coupling constant, the present mass bounds are of the order of 300
GeV. We demonstrate that at the NLC, one could detect such particles if their
mass were... | 9408250v1 |
1994-08-10 | Reggeized Gluons with a Running Coupling Constant | The equation for two reggeized gluons in the vacuum channel is generalized to
take into account the running QCD coupling constant on the basis of the
bootstrap condition for gluon reggeization. Both the gluon trajectory as a
function of momentum and the interaction as a function of distance grow like
$\log\log$ in the ... | 9408261v1 |
1994-08-22 | Diffractive Photoproduction of Jets with a Direct Pomeron Coupling at HERA | We investigate in detail the effect of a direct pomeron coupling to quarks on
the production of jets in $ep$ scattering with almost real photons. Jet
production via a direct pomeron coupling is compared with the resolved--pomeron
mechanism. We consider both direct and resolved photoproduction. Rapidity and
transverse m... | 9408340v1 |
1994-09-02 | An Analysis of Non-Oblique Corrections to the $Z b \bar b$ Vertex | We present a model--independent analysis of the $Z b \bar b$ vertex, with the
aim of constraining contributions of new physics to the left- and right--handed
couplings of the $b$. We find that the left--handed coupling of the $b$ is
quite narrowly constrained by present data, but that the right--handed coupling
is stil... | 9409211v1 |
1994-09-05 | Higgs Boson Contributions to Neutrino Production in e-e+ Collisions in a Left-Right Symmetric Model | In gauge models with bigger number of Higgs particles their couplings to
fermions are more complicated then in the standard model (SM). The influence of
the Higgs bosons exchange on the neutrino production cross section in $e^-e^+$
collision ($e^-e^+ \rightarrow \nu N$) is investigated. The study has been done
in the f... | 9409225v1 |
1994-09-23 | Model independent constraints on anomalous gauge boson self-couplings from $e^+e^-$ colliders with longitudinally polarized beams | We explore the possibility of deriving model independent limits on the
anomalous trilinear electroweak gauge boson couplings from high energy
$e^+e^-\to W^+W^-$, by combining the cross sections for the different initial
and final states polarizations integrated with suitable kinematical cuts. In
the case of the CP cons... | 9409395v1 |
1994-09-23 | Couplings of heavy mesons with soft pions in QCD | QCD sum rules are used to calculate the couplings of heavy-light quark
pseudoscalar and vector mesons ($D, D^*$ and $B, B^*$) with soft pions, both
for finite and infinitely heavy quark mass. The couplings are also computed in
the framework of a QCD relativistic potential model; in this approach the
relativistic correc... | 9409397v1 |
1994-09-30 | Diffractive Meson Production and the Quark-Pomeron Coupling | Diffractive meson production at HERA offers interesting possibilities to
investigate diffractive processes and thus to learn something about the
properties of the pomeron. The most succesful phenomenological description of
the pomeron so far assumes it to couple like a $C = +1$ isoscalar photon to
single quarks. This c... | 9409451v2 |
1994-09-30 | Searching for Anomalous Weak Couplings of Heavy Flavors at the SLC and LEP | The existence of anomalous electric($\tilde \kappa$) and/or
magnetic($\kappa$) dipole moment couplings between the heavy flavor fermions
($c,b,\tau$) and the $Z$ boson can cause significant shifts in the values of
several electroweak observables currently being probed at both the SLC and LEP.
Using the good agreement b... | 9409460v1 |
1994-11-08 | Tests of gauge boson couplings in polarized $e^-γ$ collisions | Single $W$-boson production in $e^-\gamma$ collisions with polarized beams is
investigated. Helicity amplitudes for general couplings are derived and their
properties are discussed. The results are applied to the Standard Model (SM)
and the left-right model. In the framework of SM the updated estimates of the
measureme... | 9411243v1 |
1994-11-10 | Probing Anomalous Gauge Boson Couplings at LEP | We bound anomalous gauge boson couplings using LEP data for the $Z\rightarrow
{\overline f} f$ partial widths. We use an effective field theory formalism to
compute the one-loop corrections resulting from non-standard model three and
four gauge boson vertices. We find that measurements at LEP constrain the three
gauge ... | 9411262v1 |
1994-11-12 | Probing Anomalous Quartic Vector Boson Couplings in $e^-e^-$ Collisions | We study the incidence of genuine quartic vector boson couplings in the
reactions e-e- -> e-e-ZZ, e-\nu ZW, \nu\nu WW. We find that a linear collider
operated in the e-e- mode will provide bounds on these couplings which are
competitive with those to be obtained in the e+e- mode. | 9411277v1 |
1994-11-22 | Is there a Vector Boson Coupling to Baryon Number? | Discrepancies in measurements of the QCD running coupling constant are
consistent with a new vector gauge boson coupling to baryon number with
strength aB~0.1. Upsilon decays constrain such a boson to have a mass greater
than about 35 GeV. It is difficult to observe such a boson in Z decays, e+e-
annihilation, or hadro... | 9411355v1 |
1995-01-27 | Renormalisation-group invariance and soft supersymmetry-breaking | We show that a particular ``universal'' form for the soft-breaking couplings
in a softly broken $N=1$ supersymmetric gauge theory is renormalisation-group
invariant through two loops, provided we impose one simple condition on the
dimensionless couplings. The universal form for the trilinear couplings and
mass terms is... | 9501395v2 |
1995-02-16 | The Gluon Condensate and Running Coupling of QCD | An expression for the photon condensate in quantum electrodynamics is
presented and generalized to deduce a simple relation between the gluon
condensate and the running coupling constant of quantum chromodynamics (QCD).
Ambiguities in defining the condensates are discussed. The values of the gluon
condensate from some ... | 9502326v1 |
1995-03-02 | The strong coupling, unification, and recent data | The prediction of the strong coupling assuming (supersymmetric) coupling
constant unification is reexamined. We find, using the new electroweak data,
$\alpha_{s}(M_{Z}) \approx 0.129 \pm 0.010$. The implications of the large
$\alpha_{s}$ value are discussed. The role played by the $Z$ beauty width is
stressed. It is al... | 9503214v1 |
1995-04-17 | Gauge Unification, Yukawa Hierarchy and the $μ$ Problem | The hierarchy in the Yukawa couplings may be the result of a gauged
horizontal $U(1)_H$ symmetry. If the mixed anomalies of the Standard Model
gauge group with $U(1)_H$ are cancelled by a Green-Schwarz mechanism, a
relation between the gauge couplings, the Yukawa couplings and the $\mu$-term
arises. Assuming that at a ... | 9504312v1 |
1995-04-17 | New LEP bounds on $B$-violating scalar couplings: R-parity violating supersymmetry or diquarks | We use the precision electroweak data at LEP to place bounds on $B$-violating
Yukawa couplings, two theoretically appealing examples being provided by
$R$-parity--violating supersymmetry and diquarks. The couplings involving the
third generation quarks are most severely constrained. These bounds are
complementary to th... | 9504314v1 |
1995-06-05 | Probing Trilinear Gauge Boson Couplings at Colliders | A direct measurement of the trilinear $WW\gamma$ and $WWZ$ couplings is
possible in the pair production of electroweak bosons at $e^+e^-$ and hadron
colliders. This talk addresses some of the theoretical issues: the
parameterization of ``anomalous couplings'' in terms of form factors and
effective Lagrangians, the comp... | 9506239v1 |
1995-06-12 | Gauge Coupling Unification in General SUSY Models | We study the effects of additional fields on the unification of gauge
couplings in supersymmetric models. We find that the effects are quite
constrained by the requirement of SU(5) gauge invariance. In general, we find
that any extension of the MSSM will form complete SU(5) multiplets or spoil
gauge coupling unificatio... | 9506296v1 |
1995-06-14 | Studying Anomalous $WWγ$ and $WWZ$ Couplings with Polarized $p\bar{p}$ Collisions | We calculate tree-level cross-sections for $W^{+}\gamma$ and $W^{+}W^{-}$
production in proton-antiproton collisions, with one $W$ decaying to leptons,
with anomalous electroweak triple-boson coupling parameters $\Delta\kappa$ and
$\lambda$. We compare the unpolarized cross-sections to those for a polarized
proton beam... | 9506327v1 |
1995-07-03 | Interpolating fields for spin-1 mesons | Three commonly used types of effective theories for vector mesons are shown
to correspond to different choices of interpolating field for spin-1 particles
and the rules for transforming between them are described. The choice of fields
that transform homogeneously under the nonlinear realisation of chiral symmetry
impos... | 9507202v1 |
1995-11-11 | Study of Anomalous Couplings at a $500$~GeV $e^+e^-$ Linear Collider with Polarized Beams | We consider the possibility of observing deviations from the Standard Model
gauge-boson self-couplings at a future $500$~GeV $e^+ e^-$ linear collider. We
concentrate on the case in which the electroweak symmetry breaking sector is
strongly interacting and there are no new resonances within reach of the
collider. We fi... | 9511298v1 |
1995-11-24 | Four-Body Chiral Order Parameters in the Massless Fermion Phase | The fermion four-point functions and condensates as the chiral symmetry order
parameters are calculated analytically in U(1) gauge theory in the massless
phase. It is shown that in leading order of the loop expansion of the effective
action, there is a critical coupling for the nonperturbative parity-invariant
chiralit... | 9511403v1 |
1995-12-23 | Towards Yukawa unification in a strongly Yukawa coupling model | For strong enough Yukawa coupling the electroweak standard model fermion
finds it energetically advantageous to transform itself into a bound state in
the hedgehog background of Higgs field in semiclassical approximation. By
considering the bound states give the masses for lepton and quark, we found
that all the strong... | 9512412v1 |
1995-12-26 | Phenomenological constraints on a scale-dependent gravitational coupling | We investigate the astrophysical and cosmological implications of the
recently proposed idea of a running gravitational coupling on macroscopic
scales. We find that when applied to the rotation curves of galaxies, their
flatness requires still the presence of dark matter. Bounds on the variation of
the gravitational co... | 9512431v1 |
1996-01-31 | Upper bound on all products of R-parity violating couplings $λ'$ and $λ''$ from proton decay | We prove that {\em any} product of R-parity violating couplings $\lambda'$
(L-violating) and $\lambda''$ (B-violating) can be strongly restricted by
proton decay data. For any pair $\lambda'$ and $\lambda''$ the decay exists at
least at one loop level. For squark masses below 1 TeV we find the conservative
bounds $|\la... | 9601387v1 |
1996-02-16 | Z Anomalous Couplings and the Polarization Asymmetry in $γe \to Ze$ | We extend our previous analysis of the sensitivity of the energy dependence
of the polarization asymmetry in $\gamma e \to W\nu$ to the possible existence
of anomalous trilinear gauge couplings to the $\gamma e \to Ze$ case. We find
that by combining the constraints imposed by both the energy dependence of the
total cr... | 9602331v1 |
1996-04-09 | Channel-Coupling Effects in High-Energy Hadron Collisions | The Two-Gluon Model of the Pomeron predicts strongly size-dependent
high-energy hadron cross sections. Yet experimental cross sections for radially
excited mesons appear surprisingly close in value. The strong coupling of these
mesons in hadron collisions also predicted by the model permits a qualitative
understanding ... | 9604277v1 |
1996-05-20 | The Polarization Asymmetry and Triple Gauge Boson Couplings in $γ e$ Collisions at the NLC | We examine the capability of the NLC in the $\gamma e$ collider mode to probe
the CP-conserving $\gamma WW$ and $\gamma ZZ$ anomalous couplings through the
use of the polarization asymmetry. When combined with other measurements, very
strong constraints on both varieties of anomalous couplings can be obtained.
[To appe... | 9605352v1 |
1996-07-04 | Probing Higgs Couplings in e^+ e^- \to γγγ | We investigate the existence of anomalous Higgs boson couplings,
$H\gamma\gamma$ and $HZ\gamma$, through the analysis of the process $e^+ e^-
\to \gamma\gamma\gamma$ at LEP2 energies. We suggest some kinematical cuts to
improve the signal to background ratio and determine the capability of LEP2 to
impose bounds on thos... | 9607241v1 |
1996-07-24 | Constraining a CP-violating WWV coupling from the W^+W^- threshold cross section at LEP2 | The most general form of the $WWZ$ and $WW\gamma$ interaction contains a
$CP$-violating term which has the same threshold behaviour as the Standard
Model $\ee \to \ww$ cross section. We calculate the cross section as a function
of the corresponding anomalous coupling, and estimate the bounds which can be
obtained from ... | 9607420v1 |
1996-08-06 | Goldstino Couplings to Matter | A nonlinearly realized supersymmetric action describing the invariant
couplings of the Goldstino to matter is constructed. Using the Akulov-Volkov
Lagrangian, any operator can be made part of a supersymmetric invariant action.
Of particular interest are interaction terms which include the product of the
Akulov-Volkov L... | 9608243v1 |
1996-08-08 | Determination of the $Z'$ Mass and Couplings Below Threshold at the NLC | We investigate the capability of the NLC to indirectly determine both the
mass as well as the couplings to leptons and $b$-quarks of a new neutral gauge
boson below direct production threshold. By using data collected at several
different values of the collider center of mass energy, we demonstrate how this
can be done... | 9608274v1 |
1996-09-13 | Observability at LEP2 hadronic channels of a Z' with small lepton couplings | We consider the effects of a number of models with one extra $Z$, with
enhanced couplings to quarks, in the final \underline{hadronic} channels at
LEP2. We show that, for a number of representative cases, visible effects could
be produced even for very low values of the \underline{lepton} couplings, much
smaller than t... | 9609347v1 |
1996-09-25 | The Polarization Asymmetry in $γe$ Collisions at the NLC and Triple Gauge Boson Couplings | The capability of the NLC in the $\gamma e$ collider mode to probe the
CP-conserving $\gamma WW$ and $\gamma ZZ$ anomalous couplings through the use
of the polarization asymmetry is examined. When combined with other
measurements, very strong constraints on both varieties of anomalous couplings
can be obtained. We show... | 9609461v1 |
1996-10-28 | Study of Z' Couplings to Leptons and Quarks at NLC | The discovery of a Z' and the measurement of Z' couplings to fermions are
main tasks of future colliders. Here, the possibilities to measure Z' f \bar f
couplings at an NLC operating below a Z' resonance are studied. In dependence
on the mass of the Z' and the collider parameters one will be able to
discriminate betwee... | 9610513v1 |
1996-11-05 | Anomalous t-c-g coupling: The connection between single top production and top decay | Continuing earlier work, we examine the constraint on an anomalous t-c-g
coupling from top quark decay. We find that from current CDF measurements of
the branching ratio $t \rightarrow W b$, the minimum scale at which new physics
can strongly modify the t-c-g coupling is \Ltcg $\geq$ about 950 GeV. At the
upgraded Teva... | 9611244v1 |
1996-11-18 | Bound on R-parity violating couplings from nonleptonic B decay | The effective Hamiltonian for the R-parity violating couplings induced
nonleptonic decay $B^-\to K^-K^0$ is calculated including leading log QCD
corrections running from $m_{\tilde q}$, the mass of the up-type squark, to
$m_b$. Experimental upper limit of this decay is used to give the bound on the
R-parity violating c... | 9611351v1 |
1996-11-20 | Why Hybrid Meson Coupling to Two S-wave Mesons is Suppressed | We introduce strong interaction selection rules for the two-body decay and
production of hybrid and conventional mesons coupling to two S-wave hybrid or
conventional mesons. The rules arise from symmetrization in states in the limit
of non-relativistically moving quarks. The conditions under which hybrid
coupling to S-... | 9611375v2 |
1996-11-27 | Pomerons and Jet Events at HERA | We study two and three jet events with a large rapidity gap at HERA. Unlike
in the Ingelman-Schlein approach we do not adscribe a structure to the Pomeron.
Instead, the coupling of the Pomeron to quarks or gluons is taken pointlike,
which makes the model easy to test: the only degrees of freedom are the
coupling consta... | 9611444v1 |
1996-12-09 | An Exploration of Below Threshold $Z'$ Mass and Coupling Determinations at the NLC | We examine of the capability of the Next Linear Collider to determine the
mass as well as the couplings to leptons and $b$-quarks of a new neutral gauge
boson, $Z'$, below direct production threshold. By using simulated data
collected at several different values of $\sqrt s$, we demonstrate how this can
be done in a mo... | 9612304v1 |
1996-12-19 | Systematic effects in the determination of the piNN Coupling from pbar p -> nbar n differential cross section | We show that the $\pi NN$ coupling constant extracted model-independently
from $\bar pp$ charge exchange is subject to a systematic correction, and, more
importantly, that the strong absorption in the critical region prevents a
determination of the coupling constant to high precision using this process.
This attenuates... | 9612420v2 |
1996-06-14 | Constraints on the R-parity- and Lepton-Flavor-Violating Couplings from B0 Decats to Two Charged Leptons | We derive the upper bounds on certain products of R-parity- and
lepton-flavor-violating couplings from the decays of the neutral $B$ meson into
two charged leptons. These modes of $B^0$ decays can constrain the product
combinations of the couplings with one or more heavy generation indices. We
find that most of these b... | 9701283v3 |
1997-01-22 | The Strong Coupling Constant in Grand Unified Theories | The prediction of the strong coupling constant in grand unified theories is
reviewed, first in the standard model, then in the supersymmetric version.
Various corrections are considered. The predictions in both
supergravity-induced and gauge-mediated supersymmetry breaking models are
discussed. In the region of paramet... | 9701344v1 |
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