publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2004-11-04 | Quantum Statistics and Entanglement of Two Electromagnetic Field Modes Coupled via a Mesoscopic SQUID Ring | In this paper we investigate the behaviour of a fully quantum mechanical
system consisting of a mesoscopic SQUID ring coupled to one or two
electromagnetic field modes. We show that we can use a static magnetic flux
threading the SQUID ring to control the transfer of energy, the entanglement
and the statistical propert... | 0411115v1 |
2004-11-08 | The onset of synchronization in large networks of coupled oscillators | We study the transition from incoherence to coherence in large networks of
coupled phase oscillators. We present various approximations that describe the
behavior of an appropriately defined order parameter past the transition, and
generalize recent results for the critical coupling strength. We find that,
under approp... | 0411202v2 |
2004-11-24 | Effect of spin-orbit coupling on zero-conductance resonances in asymmetrically coupled one-dimensional rings | The influence of Rashba spin-orbit coupling on zero conductance resonances
appearing in one dimensional ring asymmetrically coupled to two leads is
investigated. For this purpose, the transmission function of the corresponding
one-electron scattering problem is derived analytically and analyzed in the
complex energy pl... | 0411620v2 |
2004-11-25 | Effects of electron-phonon coupling range on the polaron formation | The polaron features due to electron-phonon interactions with different
coupling ranges are investigated by adopting a variational approach. The
ground-state energy, the spectral weight, the average kinetic energy, the mean
number of phonons, and the electron-lattice correlation function are discussed
for the system wi... | 0411651v1 |
2004-12-13 | Charge qubits in semiconductor quantum computer architectures: Tunnel coupling and decoherence | We consider charge qubits based on shallow donor electron states in silicon
and coupled quantum dots in GaAs. Specifically, we study the feasibility of
P$_2^+$ charge qubits in Si, focusing on single qubit properties in terms of
tunnel coupling between the two phosphorus donors and qubit decoherence caused
by electron-... | 0412340v1 |
2005-01-27 | Strongly Enhanced Hole-Phonon Coupling in the Metallic State of the Dilute Two-Dimensional Hole Gas | We have studied the temperature dependent phonon emission rate $P$($T$) of a
strongly interacting ($r_s\geq$22) dilute 2D GaAs hole system using a standard
carrier heating technique. In the still poorly understood metallic state, we
observe that $P$($T$) changes from $P$($T$)$\sim T^5$ to $P$($T$)$\sim T^7$
above 100mK... | 0501686v1 |
2005-03-07 | Thermal enhancement of the antiferromagnetic exchange coupling between Fe epilayers separated by a crystalline ZnSe spacer | We have put into evidence the existence of an antiferromagnetic coupling
between iron epilayers separated by a ZnSe crystalline semiconductor. The
effect has been observed for ZnSe spacers thinner than 4 nm at
room-temperature. The coupling constant increases linearly with temperature
with a constant slope of ~5.5x 10-... | 0503148v1 |
2005-03-09 | Tunable Fano effect in parallel-coupled double quantum dot system | With the help of the Green function technique and the equation of motion
approach, the electronic transport through a parallel-coupled double quantum
dot(DQD) is theoretically studied. Owing to the inter-dot coupling, the bonding
and antibonding states of the artificial quantum-dot-molecule may constitute an
appropriat... | 0503204v3 |
2005-03-10 | Exciton and negative trion dissociation by an external electric field in vertically coupled quantum dots | We study the Stark effect for an exciton confined in a pair of vertically
coupled quantum dots. A single-band approximation for the hole and a parabolic
lateral confinement potential are adopted which allows for the separation of
the lateral center-of-mass motion and consequently for an exact numerical
solution of the ... | 0503244v1 |
2005-03-15 | Phase diagram of the three band half-filled Cu-O two-leg ladder | We determine the phase diagram of the half-filled two-leg ladder both at weak
and strong coupling, taking into account the Cu d_{x^2-y^2} and the O p_x and
p_y orbitals. At weak coupling, renormalization group flows are interpreted
with the use of bosonization. Two different models with and without outer
oxygen orbital... | 0503380v2 |
2005-04-13 | Quantum phase transition and sliding Luttinger liquid in coupled t-J chains | Using a recently proposed perturbative numerical renormalization-group
algorithm, we explore the connection between quantum criticality and the
emergence of Luttinger liquid physics in $t-J$ chains coupled by frustrated
interactions. This study is built on an earlier finding that at the maximally
frustrated point, the ... | 0504306v1 |
2005-05-17 | Renormalization-group approach to superconductivity: from weak to strong electron-phonon coupling | We present the numerical solution of the renormalization group (RG) equations
derived in Ref. [1], for the problem of superconductivity in the presence of
both electron-electron and electron-phonon coupling at zero temperature. We
study the instability of a Fermi liquid to a superconductor and the RG flow of
the coupli... | 0505426v1 |
2005-05-25 | Strong electron-phonon coupling in delta-phase stabilized Pu | Heat capacity measurements of the delta-phase stabilized alloy Pu-Al suggest
that strong electron-phonon coupling is required to explain the moderate
renormalization of the electronic density of states near the Fermi energy. We
calculate the heat capacity contributions from the lattice and electronic
degrees of freedom... | 0505620v1 |
2005-06-23 | Nondissipative Spin Hall Effect via Quantized Edge Transport | The spin Hall effect in a two-dimensional electron system on honeycomb
lattice with both intrinsic and Rashba spin-orbit couplings is studied
numerically. Integer quantized spin Hall conductance is obtained at zero Rashba
coupling limit when electron Fermi energy lies in the energy gap created by the
intrinsic spin-orb... | 0506589v2 |
2005-06-28 | Stable and unstable vector dark solitons of coupled nonlinear Schrödinger equations. Application to two-component Bose-Einstein condensates | Dynamics of vector dark solitons in two-component Bose-Einstein condensates
is studied within the framework of the coupled one-dimensional nonlinear
Schr\"odinger (NLS) equations. We consider the small amplitude limit in which
the coupled NLS equations are reduced to the coupled Korteweg-de Vries (KdV)
equations. For a... | 0506718v1 |
2005-07-13 | Dephasing of a flux-qubit coupled to a harmonic oscillator | Decoherence in superconducting qubits is known to arise because of a variety
of environmental degrees of freedom. In this article, we focus on the influence
of thermal fluctuations in a weakly damped circuit resonance coupled to the
qubit. Because of the coupling, the qubit frequency is shifted by an amount $n
\delta \... | 0507290v1 |
2005-07-13 | Role of spin-orbit coupling on the spin triplet pairing in Na_{x}CoO_{2}yH_{2}O I: d-vector under zero magnetic field | The d-vector in possibile spin triplet superconductor Na_{x}CoO_{2}yH_{2}O is
microscopically investigated on the basis of the multi-orbital Hubbard model
including the atomic spin-orbit coupling. As a result of the perturbation
theory, we obtain the stable spin triplet superconductivity where the p-wave
and f-wave sta... | 0507305v1 |
2005-07-21 | Controllable coupling between flux qubits | We propose an experimentally realizable method to control the coupling
between two flux qubits. In our proposal, the bias fluxes are always fixed for
these two inductively-coupled qubits. The detuning of these two qubits can be
initially chosen to be sufficiently large, so that their initial interbit
coupling is almost... | 0507496v5 |
2005-07-21 | Spin relaxation under identical Dresselhaus and Rashba coupling strengths in GaAs quantum wells | Spin relaxation under identical Dresselhaus and Rashba coupling strengths in
GaAs quantum wells is studied in both the traditional collinear statistics,
where the energy spectra do not contain the spin-orbit coupling terms, and the
helix statistics, where the spin-orbit couplings are included in the energy
spectra. We ... | 0507497v3 |
2005-07-25 | Strong coupling superconductivity due to massless boson exchange | We solve the problem of fermionic pairing mediated by a massless boson in the
limit of large coupling constant. At weak coupling, the transition temperature
is exponentially small and superconductivity is robust against phase
fluctuation. In the strong coupling limit, the pair formation occurs at a
temperature of the o... | 0507562v1 |
2005-08-04 | Dissipate locally, couple globally: a sharp transition from decoupling to infinite range coupling in Josephson arrays with on-site dissipation | We study the T=0 normal to superconducting transition of Josephson arrays
with {\it on-site} dissipation. A perturbative renormalization group solution
is given. Like the previously studied case of {\it bond} dissipation (BD), this
is a "floating" to coupled (FC) phase transition. {\it Unlike} the BD
transition, at whi... | 0508138v2 |
2005-08-06 | Random replicators with asymmetric couplings | Systems of interacting random replicators are studied using generating
functional techniques. While replica analyses of such models are limited to
systems with symmetric couplings, dynamical approaches as presented here allow
specifically to address cases with asymmetric interactions where there is no
Lyapunov function... | 0508174v3 |
2005-08-09 | Magnetic Coupling Between Non-Magnetic Ions: Eu3+ in EuN and EuP | We consider the electronic structure of, and magnetic exchange (spin)
interactions between, nominally nonmagnetic Eu^3+ ions (4f^6, S=3, L=3, J=0)
within the context of the rocksalt structure compounds EuN and EuP. Both
compounds are ionic [Eu^3+; N^3- and P^3-] semimetals similar to isovalent GdN.
Treating the spin po... | 0508241v1 |
2005-09-05 | Effective electron-phonon coupling and polaronic transition in the presence of strong correlation | We study the Hubbard-Holstein model using slave-boson mean-field and a
variation al Lang-Firsov transformation. We identify weak and strong e-ph
coupling solutions, whose stability depends both on the bare e-ph coupling and
on the correlation strength. At mean field level the evolution from weak to
strong electron-phon... | 0509090v2 |
2005-09-28 | Antiferromagnetically coupled CoFeB/Ru/CoFeB trilayers | This work reports on the magnetic interlayer coupling between two amorphous
CoFeB layers, separated by a thin Ru spacer. We observe an antiferromagnetic
coupling which oscillates as a function of the Ru thickness x, with the second
antiferromagnetic maximum found for x=1.0 to 1.1 nm. We have studied the
switching of a ... | 0509749v1 |
2005-10-08 | Electron-phonon coupling as an order-one problem | The coupling between electrons and phonons plays important roles in physics,
chemistry and biology. However, the accurate calculation of the electron-phonon
coupling constants is computationally expensive as it involves solving the
Schrodinger equation for O(N) nuclear configurations, where N is the number of
nuclei. H... | 0510205v1 |
2005-10-09 | A multi-channel fixed point for a Kondo spin coupled to a junction of Luttinger liquids | We study a system of an impurity spin coupled to a junction of several
Tomonaga-Luttinger liquids using a renormalization group scheme. For the
decoupled S-matrix at the junction, there is a range of Kondo couplings which
flow to a multi-channel fixed point for repulsive inter-electron interactions;
this is associated ... | 0510206v2 |
2005-12-12 | Tunable coupling scheme for flux qubits at the optimal point | We discuss a practical design for tunably coupling a pair of flux qubits via
the quantum inductance of a third high-frequency qubit. The design is
particularly well suited for realizing a recently proposed microwave-induced
parametric coupling scheme. This is attractive because the qubits can always
remain at their opt... | 0512238v2 |
2006-03-14 | Spin entanglement induced by spin-orbit interactions in coupled quantum dots | We theoretically explore the possibility of creating spin quantum
entanglement in a system of two electrons confined respectively in two
vertically coupled quantum dots in the presence of Rashba type spin-orbit
coupling. We find that the system can be described by a generalized Jaynes -
Cummings model of two modes boso... | 0603363v2 |
2006-03-22 | Electronic structure and exchange constants in magnetic semiconductors digital alloys: chemical and band-gap effects | First-principles simulations have been performed for [001]-ordered Mn/Ge and
Mn/GaAs "digital alloys", focusing on the effects of i) a larger band-gap and
ii) a different semiconducting host on the electronic structure of the magnetic
semiconductors of interest. Our results for the exchange constants in Mn/Ge,
evaluate... | 0603589v1 |
2006-04-27 | Orbital and spin relaxation in single and coupled quantum dots | Phonon-induced orbital and spin relaxation rates of single electron states in
lateral single and double quantum dots are obtained numerically for realistic
materials parameters. The rates are calculated as a function of magnetic field
and interdot coupling, at various field and quantum dot orientations. It is
found tha... | 0604633v1 |
2006-06-01 | Entanglement and Bell States in Superconducting Flux Qubits | We theoretically study macroscopic quantum entanglement in two
superconducting flux qubits. To manipulate the state of two flux qubits, a
Josephson junction is introduced in the connecting loop coupling the qubits.
Increasing the coupling energy of the Josephson junction makes it possible to
achieve relatively strong c... | 0606034v2 |
2006-06-05 | Wither the sliding Luttinger liquid phase in the planar pyrochlore | Using series expansion based on the flow equation method we study the zero
temperature properties of the spin-1/2 planar pyrochlore antiferromagnet in the
limit of strong diagonal coupling. Starting from the limit of decoupled crossed
dimers we analyze the evolution of the ground state energy and the elementary
triplet... | 0606074v1 |
2006-06-29 | Analysis of Strong-Coupling Parameters for Superfluid 3He | Superfluid $^{3}$He experiments show strong deviation from the weak-coupling
limit of the Ginzburg-Landau theory, and this discrepancy grows with increasing
pressure. Strong-coupling contributions to the quasiparticle interactions are
known to account for this effect and they are manifest in the five
$\beta$-coefficien... | 0606786v2 |
2006-07-03 | Direct observation of acoustic phonon mediated relaxation between coupled exciton states in a single quantum dot molecule | We probe acoustic phonon mediated relaxation between tunnel coupled exciton
states in an individual quantum dot molecule in which the inter-dot quantum
coupling and energy separation between exciton states is continuously tuned
using static electric field. Time resolved and temperature dependent optical
spectroscopy ar... | 0607023v1 |
2006-07-24 | Synergistic Polaron Formation in the Hubbard-Holstein Model at Small Doping | We study the effect of dynamical Holstein phonons on the physics of the
Hubbard model at small doping using the dynamical cluster approximation on a
$2\times2$ cluster. Non-local antiferromagnetic correlations are found to
significantly enhance the electron-phonon coupling, resulting in polaron
formation for moderate c... | 0607623v1 |
2006-08-01 | Reentrant Synchronization and Pattern Formation in Pacemaker-Entrained Kuramoto Oscillators | We study phase entrainment of Kuramoto oscillators under different conditions
on the interaction range and the natural frequencies. In the first part the
oscillators are entrained by a pacemaker acting like an impurity or a defect.
We analytically derive the entrainment frequency for arbitrary interaction
range and the... | 0608021v1 |
2006-08-08 | Dynamics of capacitively coupled double quantum dots | We consider a double dot system of equivalent, capacitively coupled
semiconducting quantum dots, each coupled to its own lead, in a regime where
there are two electrons on the double dot. Employing the numerical
renormalization group, we focus here on single-particle dynamics and the
zero-bias conductance, considering ... | 0608186v1 |
2006-08-10 | Antiferromagnetic metal to heavy-fermion metal quantum phase transition in the Kondo lattice model: A strong coupling approach | We study the quantum phase transition from an antiferromagnetic metal to a
heavy fermion metal in the Kondo lattice model. Based on the strong coupling
approach we {\it first} diagonalize the Kondo coupling term. Since this strong
coupling approach makes the resulting Kondo term {\it relevant}, the Kondo
hybridization ... | 0608235v3 |
2006-10-17 | Structural and magnetic dimers in the spin-gapped system CuTe2O5 | We investigated the magnetic properties of the system CuTe2O5 by
susceptibility and electron spin resonance measurements. The anisotropy of the
effective g-factors and the ESR linewidth indicates that the anticipated
structural dimer does not correspond to the singlet-forming magnetic dimer.
Moreover, the spin suscepti... | 0610458v1 |
2006-12-06 | Frustrated Quantum Antiferromagnets: Application of High-Order Coupled Cluster Method | We report on recent results for strongly frustrated quantum $J_1$-$J_2$
antiferromagnets in dimensionality d=1,2,3 obtained by the coupled cluster
method (CCM). We demonstrate that the CCM in high orders of approximation
allows us to investigate quantum phase transitions driven by frustration and to
discuss novel quant... | 0612146v1 |
2007-01-05 | Deformation of SU(4) singlet spin-orbital state due to Hund's rule coupling | We investigate the ground-state property and the excitation gap of a
one-dimensional spin-orbital model with isotropic spin and anisotropic orbital
exchange interactions, which represents the strong-coupling limit of a
two-orbital Hubbard model including the Hund's rule coupling ($J$) at quarter
filling, by using a den... | 0701092v1 |
2007-01-15 | Hall Conductance of a Two-Dimensional Electron Gas with Spin-Orbit Coupling at the Presence of Lateral Periodic Potential | We evaluate the distribution of Hall conductances in magnetic subbands of
two-dimensional electron gas with Rashba spin-orbit (SO) coupling placed in a
periodic potential and perpendicular magnetic field. In this semiconductor
structure the spin-orbit coupling mixes the states of different magnetic
subbands and changes... | 0701316v1 |
2007-01-17 | Spin polarization effects in a two dimensional mesoscopic electronic structure with Rashba spin-orbit and lateral confinement | Because of the peculiar coupling of spatial and spin degrees of freedom
effected by the Rashba spin-orbit interaction, lateral confinement of a two
dimensional electronic system leads to a finite transverse spin polarization
near the longitudinal edges of a current carrying quantum wire. The sign of
this component of t... | 0701415v1 |
2007-02-08 | Dissipation can enhance quantum effects | Usually one finds that dissipation tends to make a quantum system more
classical in nature. In this paper we study the effect of momentum dissipation
on a quantum system. The momentum of the particle is coupled bilinearly to the
momenta of a harmonic oscillator heat bath. For a harmonic oscillator system we
find that t... | 0702205v1 |
2007-02-08 | Excitons in coupled InAs/InP self-assembled quantum wires | Optical transitions in coupled InAs/InP self-assembled quantum wires are
studied within the single-band effective mass approximation including effects
due to strain. Both vertically and horizontally coupled quantum wires are
investigated and the ground state, excited states and the photoluminescence
peak energies are c... | 0702206v1 |
2007-02-25 | Coupled Effects in Quantum Dot Nanostructures with Nonlinear Strain and Bridging Modelling Scales | We demonstrate that the conventional application of linear models to the
analysis of optoelectromechanical properties of nanostructures in bandstructure
engineering could be inadequate. The focus of the present paper is on a model
based on the coupled Schrodinger-Poisson system where we account consistently
for the pie... | 0702577v1 |
2007-02-28 | Renormalization group approach to anisotropic superconductivity | The superconducting instability of the Fermi liquid state is investigated by
considering anisotropic electron-boson couplings. Both electron-electron
interactions and anisotropic electron-boson couplings are treated with a
renormalization-group method that takes into account retardation effects.
Considering a non-inter... | 0702673v2 |
2007-03-22 | Electron-phonon effects on spin-orbit split bands of two dimensional systems | The electronic self-energy is studied for a two dimensional electron gas
coupled to a spin-orbit Rashba field and interacting with dispersionless
phonons. For the case of a momentum independent electron-phonon coupling
(Holstein model) we solve numerically the self-consistent non-crossing
approximation for the self-ene... | 0703584v2 |
2007-03-23 | Boundary quantum criticality in models of magnetic impurities coupled to bosonic baths | We investigate quantum impurity problems, where a local magnetic moment is
coupled to the spin density of a bosonic environment, leading to bosonic
versions of the standard Kondo and Anderson impurity models. In a physical
situation, these bosonic environments can correspond either to deconfined
spinons in certain clas... | 0703609v1 |
1995-09-01 | Contact interactions on graph superlattices | We consider a quantum mechanical particle living on a graph and discuss the
behaviour of its wavefunction at graph vertices. In addition to the standard
(or delta type) boundary conditions with continuous wavefunctions, we
investigate two types of a singular coupling which are analogous to the delta'
interaction and it... | 9509001v1 |
1995-03-10 | On Singularities and Instability for Different Couplings between Scalar Field and Multidimensional Geometry | We consider a multidimensional model of the universe given as a
$D$-dimensional geometry, represented by a Riemannian manifold $(M,g)$ with
arbitrary signature of $g$, $M= \R\times M_1\times \cdots \times M_n$, where
the $M_i$ of dimension $d_i$ are Einstein spaces, compact for $i>1$. For
Lagrangian models $L(R,\phi)$ ... | 9503019v1 |
1997-03-07 | Extra Dimensions, Nonminimal Couplings, Horizons and Wormholes | Static, spherically symmetric configurations of gravity with nonminimally
coupled scalar fields are considered in D-dimensional space-times in the
framework of generalized scalar-tensor theories. We seek special cases when the
system has no naked singularity but instead forms either a black hole, or a
wormhole. General... | 9703020v1 |
1997-12-17 | Testing the Equivalence Principle in Quantum Physics | We showed in a previous paper that a wide class of nonmetric theories of
gravity encompassed by the $\chi g$ formalism predict that the speed of light
rays depends on the their polarization direction relative to directions singled
out by the gravitational field. This gravity-induced birefringence of space is
a violatio... | 9712076v1 |
1999-08-09 | Self-similar cosmological solutions with a non-minimally coupled scalar field | We present self-similar cosmological solutions for a barotropic fluid plus
scalar field with Brans-Dicke-type coupling to the spacetime curvature and an
arbitrary power-law potential energy. We identify all the fixed points in the
autonomous phase-plane, including a scaling solution where the fluid density
scales with ... | 9908026v2 |
2002-04-19 | Possible evidence from laboratory measurements for a latitude and longitude dependence of G | Stability arguments suggest that the Kaluza-Klein (KK) internal scalar field,
$\Phi$, should be coupled to some external fields. An external bulk real scalar
field, $\psi$, minimally coupled to gravity is proved to be satisfactory. At
low temperature, the coupling of $\psi$ to the electromagnetic (EM) field
allows $\Ph... | 0204064v1 |
2003-09-28 | A $T_0$-discrete universe model with five low-energy fundamental interactions and the coupling constants hierarchy | A quantum model of universe is constructed in which values of dimensionless
coupling constants of the fundamental interactions (including the cosmological
constant) are determined via certain topological invariants of manifolds
forming finite ensembles of 3D Seifert fibrations. The characteristic values of
the coupling... | 0309133v1 |
2004-02-12 | Solar constraints on new couplings between electromagnetism and gravity | The unification of quantum field theory and general relativity is a
fundamental goal of modern physics. In many cases, theoretical efforts to
achieve this goal introduce auxiliary gravitational fields, ones in addition to
the familiar symmetric second-rank tensor potential of general relativity, and
lead to nonmetric t... | 0402055v1 |
2005-12-31 | Coupling of Radial and Axial non-Radial Oscillations of Compact Stars: Gravitational Waves from first-order Differential Rotation | We investigate the non-linear coupling between radial and non-radial
oscillations of static spherically symmetric neutron stars as a possible
mechanism for the generation of gravitational waves that may lead to observable
signatures. In this paper we concentrate on the axial sector of the non-radial
perturbations. By u... | 0601001v1 |
2006-08-09 | Two-dimensional gravity with a dynamical aether | We investigate the two-dimensional behavior of gravity coupled to a dynamical
unit timelike vector field, i.e. "Einstein-aether theory". The classical
solutions of this theory in two dimensions depend on one coupling constant.
When this coupling is positive the only solutions are (i) flat spacetime with
constant aether... | 0608052v1 |
2006-10-10 | Gravity coupled to a scalar field in extra dimensions | In d+1 dimensions we solve the equations of motion for the case of gravity
minimally or conformally coupled to a scalar field. For the minimally coupled
system the equations can either be solved directly or by transforming vacuum
solutions, as shown before in 3+1 dimensions by Buchdahl. In d+1 dimensions the
solutions ... | 0610048v2 |
2006-12-11 | On source coupling and the teleparallel equivalent to GR | Alternatives to the usual general relativity (GR) Riemannian framework
include Riemann-Cartan and teleparallel geometry. The ``teleparallel equivalent
of GR" (TEGR, aka GR${}_{||}$) has certain virtues, however there have been
allegations of serious source coupling limitations. Now it is quite
straightforward to show t... | 0612062v1 |
2007-02-28 | A generalization of Ryan's theorem: probing tidal coupling with gravitational waves from nearly circular, nearly equatorial, extreme-mass-ratio inspirals | Extreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals
(IMRIs)--binaries in which a stellar-mass object spirals into a massive black
hole or other massive, compact body--are important sources of gravitational
waves for LISA and LIGO, respectively. Thorne has speculated that the waves
from EMRIs and ... | 0702146v1 |
1995-03-10 | Limits on $WWZ$ and $WWγ$ couplings from $WW$ and $WZ$ production in $p\overline{p}$ collisions at $\sqrt{s} = 1.8$ TeV | Direct limits are set on $WWZ$ and $WW\gamma$ three-boson couplings in a
search for $WW$ and $WZ$ production with high transverse momentum in
$p\overline{p}$ collisions at $\sqrt{s} = 1.8$ TeV, using the Collider Detector
at Fermilab. The results are in agreement with the SU(2) $\times$ U(1) model of
electroweak intera... | 9503009v1 |
1995-03-13 | Measurement of the $ZZγ$ and $Zγγ$ Couplings in $p\bar p$ Collisions at $\sqrt{s} = 1.8$ TeV | We have directly measured the ZZ-gamma and Z-gamma-gamma couplings by
studying p pbar --> l+ l- gamma + X, (l = e, mu) events at the CM energy of
1.8$ TeV with the D0 detector at the Fermilab Tevatron Collider. A fit to the
transverse energy spectrum of the photon in the signal events, based on the
data set correspondi... | 9503010v1 |
1998-03-19 | Limits on Anomalous WWgamma and WWZ Couplings | Limits on the anomalous WWgamma and WWZ couplings are presented from a
simultaneous fit to the data samples of three gauge boson pair final states in
pbar-p collisions at sqrt(s)=1.8 TeV: Wgamma production with the W boson
decaying to enu or munu, W boson pair production with both of the W bosons
decaying to enu or mun... | 9803017v2 |
1999-05-04 | Studies of WW and WZ Production and Limits on Anomalous WWgamma and WWZ Couplings | Evidence of anomalous WW and WZ production was sought in pbar{p} collisions
at a center-of-mass energy of sqrt(s) = 1.8 TeV.
The final states $WW (WZ) to mu-nu-jet-jet + X, WZ to mu-nu-e-e + X and WZ to
e-nu-e-e + X were studied using a data sample corresponding to an integrated
luminosity of approximately 90 pb-1. N... | 9905005v1 |
2001-02-21 | Measurement of Trilinear Gauge Boson Couplings WWV, (V = Z,gamma) in e+e- Collisions at 189 GeV | Measurements of the trilinear gauge boson couplings WWgamma and WWZ are
presented using the data taken by DELPHI in 1998 at a centre-of-mass energy of
189 GeV and combined with DELPHI data at 183 GeV. Values are determined for
Delta(g_1^Z) and Delta(kappa_gamma), the differences of the WWZ charge coupling
and of the WW... | 0102041v1 |
2006-08-04 | Limits on anomalous trilinear gauge couplings from WW->e+e-, WW->emu, and WW->mu+mu- events from p-pbar collisions at sqrt(s)=1.96 TeV | Limits are set on anomalous WWgamma and WWZ trilinear gauge couplings using
W+W- -> e+e-, W+W- -> e mu, and W+W- -> mu+mu- events. The data set was
collected by the Run II D0 detector at the Fermilab Tevatron Collider and
corresponds to approximately 250 inverse pb of integrated luminosity at sqrt(s)
= 1.96 TeV. Under ... | 0608011v1 |
1993-01-21 | SU(N) Quantum Antiferromagnets and the Phase Structure of QED in the Strong Coupling Limit | We examine the strong coupling limit of both compact and non compact QED on a
lattice with staggered fermions. We show that every SU(N) antiferromagnet with
spins in a particular fundamental representation of the SU(N) Lie Algebra and
with nearest neighbor couplings on a bipartite lattice is exactly equivalent to
the i... | 9301014v1 |
1994-11-11 | Two-loop computation of a finite volume running coupling on the lattice | In pure SU(2) gauge theory we compute the two-loop coefficient in the
relation between the lattice bare coupling and the running coupling defined
through the Schroedinger functional. This result is required to relate the
latter to the MSbar-coupling in our programme to compute alpha_s. In addition
it allows us to imple... | 9411018v2 |
1994-12-23 | Running coupling constant and correlation length from Wilson loops | We consider a definition of the QCD running coupling constant $\alpha(\mu)$
related to Wilson loops of size $r{\times}t$ with arbitrary fixed $t/r$. The
schemes defined by these couplings are very close to the $\overline{\rm MS}$
scheme (i.e.\ the one-loop perturbative correction to the coupling is small)
for all value... | 9412099v1 |
1995-02-27 | Two Loop Computation of a Running Coupling in Lattice Yang-Mills Theory | We compute the two loop coefficient in the relation between the lattice bare
coupling and the running coupling defined through the Schroedinger functional
for the case of pure SU(2) gauge theory. This result is needed as one
computational component to relate the latter to the MSbar-coupling, and it
allows us to impleme... | 9502021v2 |
1996-05-31 | Compact U(1) Lattice Gauge-Higgs Theory with Monopole Suppression | We investigate a model of a U(1)-Higgs theory on the lattice with compact
gauge fields but completely suppressed (elementary) monopoles. We study the
model at two values of the quartic Higgs self-coupling, a strong coupling,
$\lambda = 3.0$, and a weak coupling, $\lambda=0.01$. We map out the phase
diagrams and find th... | 9605043v1 |
1996-12-05 | A Strong-Coupling Analysis of the Lattice $CP^{N-1}$ Models in the Presence of a $θ$ Term | A $\theta$ term, which couples to topological charge, is added to the lattice
$CP^{N-1}$ model. The strong-coupling character expansion is developed. The
series for the free energy and mass gap are respectively computed to tenth
order and fourth order. Several features of the strong-coupling analysis
emerge. One is the... | 9612004v1 |
1997-11-19 | Strongly coupled U(1) lattice gauge theory as a microscopic model of Yukawa theory | Dynamical chiral symmetry breaking in a strongly coupled U(1) lattice gauge
model with charged fermions and scalar is investigated by numerical simulation.
Several composite neutral states are observed, in particular a massive fermion.
In the vicinity of the tricritical point of this model we study the effective
Yukawa... | 9711038v2 |
1998-07-20 | Towards a lattice determination of the $B^\ast B π$ coupling | The coupling $g_{B^\ast B \pi}$ is related to the form factor at zero
momentum of the axial current between $B^\ast$- and $B$-states. This form
factor is evaluated on the lattice using static heavy quarks and light quark
propagators determined by a stochastic inversion of the fermionic bilinear. The
$\gBBP$ coupling is... | 9807032v1 |
2000-12-23 | Helicity modulus as renormalized coupling in the O(3) sigma-model | For the family of O(n) invariant nonlinear sigma-models we consider boundary
conditions that are periodic up to an O(n) rotation. The helicity modulus is
related to the change in free energy under variations of the corresponding
angle. It defines a nonperturbative finite volume running coupling similar to
the Schr"odin... | 0012027v2 |
2005-01-25 | An example of optimal field cut in lattice gauge perturbation theory | We discuss the weak coupling expansion of a one plaquette SU(2) lattice gauge
theory. We show that the conventional perturbative series for the partition
function has a zero radius of convergence and is asymptotic. The average
plaquette is discontinuous at g^2=0. However, the fact that SU(2) is compact
provides a pertu... | 0501023v2 |
1992-05-11 | Dark Matter with Variable Masses | String effective theories contain a dilaton scalar field which couples to
gravity, matter and radiation. In general, particle masses will have different
dilaton couplings. We can always choose a conformal frame in which baryons have
constant masses while (non--baryonic) dark matter have variable masses, in the
context ... | 9205216v1 |
1993-01-21 | Third Generation Effects on Fermion Mass Predictions in Supersymmetric Grand Unified Theories | Relations among fermion masses and mixing angles at the scale of grand
unification are modified at lower energies by renormalization group running
induced by gauge and Yukawa couplings. In supersymmetric theories, the $b$
quark and $\tau$ lepton Yukawa couplings, as well as the $t$ quark coupling,
may cause significant... | 9301258v1 |
1993-03-24 | Determination of $Z'$ Gauge Couplings to Quarks and Leptons at Future Hadron Colliders | We point out that at future hadron colliders the ratio of cross sections for
$pp\to Z'\to \ell^+\ell^-$ in two rapidity bins is a useful probe of the
relative couplings of the $Z'$ to $u$ and $d$ quarks. Combined with the
forward-backward asymmetry, the rare decay modes $Z'\to W \ell\nu_\ell$, and
three associated prod... | 9303299v1 |
1993-08-26 | Tests on the Hierarchy of Trilinear and Quadrilinear Weak Bosons Couplings at the NLC and Comparison with the LHC/SSC | I first review a few basic guiding principles that lead to the notion of a
hierarchy of couplings in searches of New Physics involving weak bosons
processes. The hierarchies within a linear and a non-linear realization of
symmetry breaking are compared to the usual {\em phenomenological}
parameterization of the $WWV$ v... | 9308343v1 |
1994-06-16 | Hadron collider limits on anomalous $WWγ$ couplings | A next-to-leading log calculation of the reactions $pp$ and
$p\overline{p}\rightarrow W^\pm\gamma X$ is presented including a tri-boson
gauge coupling from non-Standard Model contributions. Two approaches are made
for comparison. The first approach considers the tri-boson $WW\gamma$ coupling
as being uniquely fixed by ... | 9406331v1 |
1994-11-07 | $\sin^2θ_W(M_Z)$ ~in the MSSM and Unification of Couplings | We calculate ~$\sin^2\theta(M_Z)$ ~in the MSSM in terms of ~ $\alpha_{EM}$,
~$G_F$, ~$m_t$, ~$\tan\beta$ ~and SUSY mass parameters with the same accuracy
as the present calculations of ~$\sin^2\theta(M_Z)$ ~in the SM. We compare the
results with the standard leading logarithmic approximation used for SUSY
threshold cor... | 9411233v1 |
1994-11-11 | Nucleosynthesis and the Time Dependence of Fundamental Couplings | We consider the effects of the time dependence of couplings due to their
dependence on a dilaton field, as occurs in superstring theory, as well as in
gravity theories of the Jordan-Brans-Dicke type. Because the scale parameters
of couplings set by dimensional transmutation depend exponentially on the
dilaton vev, we m... | 9411272v1 |
1994-11-22 | Predictions of the Top mass in Mininal Supersymmetric Left-Right Model | The one-loop evolution of Yukawa couplings in the minimal supersymmetric
left-right model (MSUSYLR) model with a wide variation of the right handed
breaking scale $M_R$ from 1 TeV to $10^{18}$ GeV is studied assuming that all
third generation Yukawa couplings are equal and in the fixed point domain of
the top quark Yua... | 9411357v2 |
1994-12-01 | Bounds on $ΔB=1$ Couplings in the Supersymmetric Standard Model | The most general supersymmetric model contains baryon number violating terms
of the form $\lambda_{ijk}\;\ov{D}_i\, \ov{D}_j\, \ov{U}_k$ in the
superpotential. We reconsider the bounds on these couplings, assuming that
lepton number conservation ensures proton stability. These operators can
mediate $n - \ov{n}$ oscilla... | 9412208v1 |
1995-03-24 | Precise Predictions for the Masses and Couplings in the Minimal Supersymmetric Standard Model | We present selected results of our program to determine the masses, gauge
couplings, and Yukawa couplings of the minimal supersymmetric model in a full
one-loop calculation. We focus on the precise prediction of the strong coupling
alpha_s(M_Z) in the context of supersymmetric unification. We discuss the
importance of ... | 9503422v1 |
1995-03-30 | Bounds on $ΔB=1$ Couplings in the Supersymmetric Standard Model | The most general supersymmetric model contains baryon number violating terms
of the form $\lm_{ijk}\ \ov{D}_i\ \ov{D}_j\ \ov{U}_k$ in the superpotential. We
reconsider the bounds on these couplings, assuming that lepton number
conservation ensures proton stability. These operators can mediate $n-\ov{n}$
oscillations an... | 9503472v1 |
1995-04-25 | Strong-coupling expansions for chiral models of electroweak symmetry breaking | We consider chiral $U(N)\times U(N)$ models with fermions in the limit of
infinitely large local bare Yukawa coupling. When the scalar field is subject
to non-linear constraint, phase transitions in these models are seen to be
identical to those in the corresponding purely bosonic ones. Relaxing the
non-linear constrai... | 9504389v1 |
1995-06-02 | Effective couplings and Perturbative Unification | In this paper we study the influence of the threshold effects due to massive
degrees of freedom in the evolution with scale of gauge coupling constants. We
first describe in detail the (standard) mass dependent renormalization
prescription we use. This guides us to introduce and work with effective
couplings, which are... | 9506222v1 |
1995-08-02 | The Strong Coupling and the Bottom Mass in Supersymmetric Grand Unified Theories | We apply the full one-loop corrections to the masses, gauge couplings, and
Yukawa couplings in the minimal supersymmetric standard model. We focus on
predictions for the strong coupling and the bottom-quark pole mass in the
context of SU(5) supersymmetric grand unification. We discuss our results in
both the small and ... | 9508219v1 |
1995-11-09 | Gauge Coupling Unification and the Top Mass in String Models with $SU(4)\times O(4)$ Symmetry | We discuss the low energy implications of gauge coupling unification at the
string scale, taking into account string threshold corrections in the $SU(4)
{\times} O(4)$ model. We express $sin^2\theta_W$ and $a_3$ as functions of the
calculable string threshold differences and discuss simple examples of spectra
which ret... | 9511280v3 |
1995-11-29 | LEP- and low energy-bounds on R-parity-violating supersymmetric Yukawa couplings | Electroweak precision data at LEP are used to place bounds on some
$\lambda'$-type ($L$-violating) and $\lambda''$-type ($B$-violating) $R$-parity
violating supersymmetric Yukawa couplings. We consider one-loop corrections
(triangles and self-energies) induced by these couplings to the $Z$-partial
widths. The couplings... | 9511447v1 |
1996-10-16 | Trilinear anomalous gauge couplings and non-standard fermionic couplings | In this paper we do an analysis of the reaction $e^+e^-\to W^+W^-$ for
various options of the Next Linear Colliders (NLC), by considering the
possibility of deviations from the Standard Model induced by anomalous
trilinear vector boson couplings and non-standard fermionic couplings. We show
that there are strong correl... | 9610377v1 |
1996-12-13 | Subtractive Renormalization of Strong-Coupling Quenched QED in Four Dimensions | We study renormalized quenched strong-coupling QED in four dimensions in
arbitrary covariant gauge, in the Dyson-Schwinger equation formalism. Above the
chiral critical coupling, we show that there is no finite chiral limit. This
behaviour is found to be independent of the detailed choice of proper vertex,
provided tha... | 9612360v1 |
1996-12-31 | Predictions of $m_b/m_τ$ and $m_t$ in an Asymptotically Non-Free Theory | We discuss an extention of the Minimal Supersymmetric Standard Model (MSSM)
with the 4th and anti-4th generations which have $SU(2)_L\times U(1)_Y$
invariant masses. Due to the the extra generations, all three running gauge
couplings become asymptotically non--free while preserving gauge coupling
unification at the GUT... | 9612493v2 |
1997-03-21 | Forward-backward asymmetry in e+e- -> nu nubar Z from anomalous CP-odd WWZ couplings | Anomalous CP-odd W+W-Z couplings can give rise to a forward-backward
asymmetry in the Z angular distribution in the e+e- centre-of-mass frame in the
process e+e- -> nu nubar Z. Of the three CP-odd couplings possible, only the
imaginary part of one of the couplings, f_4^Z, which is C odd and P even,
contributes to the f... | 9703380v2 |
1997-04-07 | R-parity-violating SUSY effects and signals in single top production at the Tevatron | We discuss single top quark production via u^i+\bar d^j \to t+\bar b at the
Fermilab Tevatron in the minimal supersymmetric model with R-parity violation.
We find that within the allowed range of coupling constants, the lepton-number
violating couplings can give rise to observable effects when the slepton mass
lies in ... | 9704257v3 |
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