August 1993 arXiv papers — page 5

MI Dykman, DG Luchinsky, R Mannella, PVE McClintock

The kinetics of a periodically driven nonlinear oscillator, bistable in a nearly resonant field, has been investigated theoretically and through analogue experiments. An activation dependence of the probabilities of fluctuational transitions between the coexisting attractors has been observed, and the activation energies of the transitions have been calculat

MI Dykman, H Haken, Gang Hu, DG Luchinsky

The susceptibility of an overdamped Markov system fluctuating in a bistable potential of general form is obtained by analytic solution of the Fokker-Planck equation (FPE) for low noise intensities. The results are discussed in the context of the LRT theory of stochastic resonance. They go over into recent results (Gang Hu et al {\em Phys. Lett. A} {\bf 172},

M. I. Dykman, D. G. Luchinsky, R. Mannella, P. V. E. McClintock

High frequency stochastic resonance (SR) phenomena, associated with fluctuational transitions between coexisting periodic attractors, have been investigated experimentally in an electronic model of a single-well Duffing oscillator bistable in a nearly resonant field of frequency $ω_F$. It is shown that, with increasing noise intensity, the signal/noise ratio

Karl B Fisher, Marc Davis, Michael A Strauss, Amos Yahil

We examine the effect of redshift space distortions on the galaxy two-point correlation function $ξ(r_p,π)$ as a function of separations parallel ($r_p$) and perpendicular ($π$) to the line of sight. We find that the relative velocity dispersion of pairs of IRAS galaxies is $σ(r)= 317^{+40}_{-49}$ \kms at $r=1 \mpc$, consistent with previous estimates derive

R. Juszkiewicz, D. Weinberg, P. Amsterdamski, M. Chodorowski

We calculate the cosmological evolution of the 1-point probability distribution function (PDF), using an analytic approximation that combines gravitational perturbation theory with the Edgeworth expansion of the PDF. Our method applies directly to a smoothed mass density field or to the divergence of a smoothed peculiar velocity field, provided that rms fluc

P. A. Thomas, S. Vine, F. R. Pearce

Orbits in triaxial ellipsoidal potentials precess about either the major or minor axis of the ellipsoid. In standard perturbation theory it can be shown that a circular orbit will precess about the minor axis if its angular momentum vector lies in a region bounded by two great circles which pass through the intermediate axis and which are inclined with minim

P. Furlan, Alexander Ganchev, V. B. Petkova

The problem of describing the singular vectors of $\cW_3$ and $\cW_3^{(2)}$ Verma modules is addressed, viewing these algebras as BRST quantized Drinfeld-Sokolov (DS) reductions of $A^{(1)}_2\,$. Singular vectors of an $A^{(1)}_2\,$ Verma module are mapped into $\W$ algebra singular vectors and are shown to differ from the latter by terms trivial in the BRST

K. Demeterfi, I. Klebanov, J. Rodrigues

We consider the $c=1$ matrix model deformed by the operator ${1\over 2} M\Tr\Phi^{-2}$, which was conjectured by Jevicki and Yoneya to describe a two-dimensional black hole of mass $M$. We calculate the exact non-perturbative $S$-matrix and show that all the amplitudes involving an odd number of particles vanish at least to all orders of perturbation theory.

Aneesh V. Manohar, Mark B. Wise

The differential decay spectrum $dΓ/dE_e dq^2$ for the semileptonic decay of an unpolarized hadron containing a b-quark, and the decay spectrum $dΓ/dE_e dq^2 d\!\cosθ$ for polarized $Λ_b$ decay are computed to second order in the $1/m_b$ expansion. Most of the $1/m_b^2$ corrections have a simple physical interpretation, which is discussed in detail. The impl

A. Leonidov, A. Zelnikov

At the simple example of a massless scalar field propagating in the static background we study the resummed expressions for the effective action at zero and finite temperature that are free from a usual sickness of the effective action induced by massless particles.

A. Ch. Ganchev, V. B. Petkova

The BRST quantisation of the Drinfeld - Sokolov reduction is exploited to recover all singular vectors of the Virasoro algebra Verma modules from the corresponding $A^{(1)}_1\,$ ones. The two types of singular vectors are shown to be identical modulo terms trivial in the $Q_{BRST}$ cohomology. The main tool is a quantum version of the DS gauge transformation

L. V. Razumov, R. M. Weiner

We consider here the bremsstrahlung emission of photons at low and intermediate energies $ E_{lab}\le 1000 MeV/u$ of the projectile. and derive expressions more general than previous results obtained by Neuhauser which were limited to the case of isotropic systems. We find that the two-photon correlation function strongly depends not only on the space-time p

V. V. Dodonov, O. V. Man'ko, V. I. Man'ko

For N-mode light described by the Wigner function of generic Gaussian form the photon distribution function is obtained explicitly and expressed in terms of Hermite polynomial of $2N$ variables with equal pairs of indices.The mean values and dispersions of photon numbers are obtained for this generic mixed state.Generating function for photon distribution is

Jacek Graczyk, Grzegorz Swiatek

We prove that non-hyperbolic non-renormalizable quadratic polynomials are expansion inducing. For renormalizable polynomials a counterpart of this statement is that in the case of unbounded combinatorics renormalized mappings become almost quadratic. Technically, this follows from the decay of the box geometry. Specific estimates of the rate of this decay ar

R. B. Mann

The dynamics of Liouville fields coupled to gravity are investigated by applying the principle of general covariance to the Liouville action in the context of a particular form of two-dimensional dilaton gravity. The resultant field equations form a closed system for the Liouville/gravity interaction. A large class of asymptotically flat solutions to the fie

Nadeem A. Ansari, V. I. Man'ko

The even and odd coherent states are generalized for multimode case. The explicit forms for the photon distribution, Q-function and Wigner function are derived. In particular, it is shown that for two-mode case there exist strong correlations between these modes, under certain conditions, which are responsible for two-mode squeezing in case of even coherent

R. Percacci

There is a general mechanism by which certain matter fields coupled to gravity can generate a nontrivial effective potential for the conformal factor of the metric. It is based on a nonstandard regularization method, with the cutoff being defined independently of the conformal factor. This mechanism produces a coupling of the matter fields to a dilaton, and

Patricia Ball

Using the QCD sum rules approach and the complete leading--logarithmic short--distance coefficients determining the penguin--amplitude, we obtain $B(B\to K^*γ) = (6.8\pm 2.4)\cdot 10^{-5}$ for top--quark masses in the range (150--200) GeV and $|V_{cb}| = 0.035$ for $τ_B = 1.5\,\text{ps}$. The ratio to the inclusive rate is $B(B\to K^*γ)/B(B\to X_sγ) = (20\pm

H. Arthur Weldon

The first-order bremsstrahlung emission spectrum is $αdω/ω$ at zero temperature. If the radiation is emitted into a region that contains a thermal distribution of photons, then the rate is increased by a factor $1+N(ω)$ where $N(ω)$ is the Bose-Einstein function. The stimulated emission changes the spectrum to $αTdω/ω^{2}$ for $ω\ll T$. If this were correct,

Antonio Bouzas

We study the intermittency properties of two branching processes, one with a uniform and another with a singular splitting kernel. The asymptotic intermittency indices, as well as the leading corrections to the asymptotic linear regime are explicitly computed in an analytic framework. Both models are found to possess a monofractal spectrum with $φ_{q}=q-1$.

Francesco Di Renzo, Giuseppe Marchesini, Paolo Marenzoni, Enrico Onofri

We present an application of the standard Langevin dynamics to the problem of weak coupling perturbative expansions for Lattice QCD. This method can be applied to the computation of the most general observables. In this preliminary work we will concentrate in particular on the computation of the perturbative terms of the $1\times 1$ Wilson loop, up to fourth

Yuji Kobayashi

We further develop the reduced action formalism of the SU(2)-Higgs model originally given by Aoyama et.al.. Our new ansatz for the sphaleron solution makes it possible to apply this formalism to all range of the Higgs self coupling constant. Based on the formalism, we construct a bounce solution oscillating around the sphaleron.

H. -P. Eckle, T. T. Truong

The Hamiltonian limit of the corner transfer matrix (CTM) of a generalised free Fermion vertex system of finite size leads to a quantum spin Hamiltonian of the particular form: \[ {\cal H}_N=-\sum_{n=1}^{N-1}\left\{ n\left( σ_n^xσ_{n+1}^x +λσ_n^yσ_{n+1}^y +h(σ_n^z+σ_{n+1}^z) \right)\right\} \] Diagonalisation may be achieved for all pairs of parameters $(λ,h

J. Choi, R. R. Volkas

The effective potential at finite temperature is constructed within the minimal standard model when a real Higgs singlet is added on. We find that a region of parameter space exists for which one can find a first order transition strong enough to prevent the erasure due to sphalerons of baryon asymmetry, while keeping the mass of the smallest Higgs boson abo

Dinghui H. Lu, Rubin H. Landau

Bound states of the pion--nucleus system are investigated in momentum space using a microscopic optical potential with inherent energy dependences and nonlocalities arising from elementary potential models. The wave equation and computational techniques are tested, shallow levels are calculated, and a comparison is made with experiment. Deep levels are found

R. Cenni, S. Fantoni

We derive a model Hamiltonian whose ground state expectation value of any two-body operator coincides with that obtained with the Jastrow correlated wave function of the many-body Fermi system. Using this Hamiltonian we show that the variational principle can be extended to treat systems with dynamical mesons, even if in this case the concept of wave functio

G. Q. Li, R. Machleidt

A momentum-dependent mean field potential, suitable for application in the transport-model description of nucleus-nucleus collisions, is derived in a microscopic way. The derivation is based upon the Bonn meson-exchange model for the nucleon-nucleon interaction and the Dirac-Brueckner approach for nuclear matter. The properties of the microscopic mean field

Martin Goldstern

If (B_x: x in N) is a Borel family of sets, indexed by the Baire space N = omega^omega, all B_x have measure zero, and the family is increasing, then the union of all B_x also has measure zero. We give two proofs of this theorem: one in the language of set theory, using Shoenfield's theorem on Sigma-1-2 sets, the other in the language of probability theo

B. Harms, Y. Leblanc

Canonical quantization of local field theories is classical black hole spacetimes with a single horizon leads to a particle number density with a thermal distribution in equilibrium at the Hawking temperature. A complete treatment including non-local quantum gravity effects has shown however that the full "thermal vacuum" of the theory is the false v

Michael Martin Nieto, D. Rodney Truax

We propose a ladder-operator method for obtaining the squeezed states of general symmetry systems. It is a generalization of the annihilation-operator technique for obtaining the coherent states of symmetry systems. We connect this method with the minimum-uncertainty method for obtaining the squeezed and coherent states of general potential systems, and comm

E. Elizalde

Hawking's zeta function regularization procedure is shown to be rigorously and uniquely defined, thus putting and end to the spreading lore about different difficulties associated with it. Basic misconceptions, misunderstandings and errors which keep appearing in important scientific journals when dealing with this beautiful regularization method ---and

David McMullan, Izumi Tsutsui

It has been known for some time that there are many inequivalent quantizations possible when the configuration space of a system is a coset space G/H. Viewing this classical system as a constrained system on the group G, we show that these inequivalent quantizations can be recovered from a generalization of Dirac's approach to the quantization of such a

F. Lizzi, G. Marmo, G. Sparano, P. Vitale

Quantum Groups can be constructed by applying the quantization by deformation procedure to Lie groups endowed with a suitable Poisson bracket. Here we try to develop an understanding of these structures by investigating dynamical systems which are associated with this bracket. We look at $SU(2)$ and $SU(1,1)$, as submanifolds of a 4--dimensional phase space

A. Kempf

While it is possible to introduce quantum group symmetry into the framework of quantum mechanics, the general problem of how to implement quantum group symmetry into $(3+1)$ dimensional quantum field theory has not yet been solved. Here we try to estimate some features of the behaviour of bosonic modes.

Adam F. Falk, Michael E. Peskin

We discuss the production via fragmentation of excited heavy mesons and baryons, and their subsequent decay. In particular, we consider the question of whether a net polarization of the initial heavy quark may be detected, either in a polarization of the final ground state or in anisotropies in the decay products of the excited hadron. The result hinges in p

C. -P. Yuan

I briefly report on what we can learn about the top quark at hadron colliders.

R. M. Godbole

In this talk I review theoretical bounds on mass of the Higgs scalar in the Standard Model(SM) and then summarise current experimental limits from the LEP experiments. Following this I discuss the search strategies for the SM Higgs at LEP 200 and the TeV energy \eplem\ colliders which are under discussion. This will be followed by a summary of the Higgs sear

W. de Boer, R. Ehret, D. I. Kazakov

Within the Minimal Supersymmetric Grand Unified Theory (MSGUT) masses of the predicted supersymmetric particles are constrained by the world averaged values of the electroweak and strong coupling constants, the lower limits on the proton lifetime,the lower limit on the lifetime of the universe, which implies an upper limit on the dark matter density, the ele

H. Anlauf, H. D. Dahmen, P. Manakos, T. Mannel

We present the Monte Carlo event generator {\tt WOPPER} for pair production of $W$'s and their decays at high energy $e^+e^-$ colliders. {\tt WOPPER} includes the effects from finite $W$ width and focusses on the calculation of higher order electromagnetic corrections in the leading log approximation including soft photon exponentiation and explicit gene

Howard E. Haber

Present data indicates that the gluino (if it exists) must be heavier than about 95~GeV. During the next few years as the Tevatron integrated luminosity increases, gluino searches will be able to probe the mass range between 100 and 200~GeV. For masses in this range, a variety of gluino decay modes can provide viable signatures for gluino detection. Apart fr

Neil Ferguson, J. F. Wheater

We consider methods of interpolating between the crystalline and dynamically triangulated random surface models. We argue that actions based on the deviation from six of the coordination number at a site are inadequate and propose an alternative based on Alexander moves. Two simplified models, one of which has a phase transition and the other of which does n

J. J. Halliwell

I give an informal overview of the decoherent histories approach to quantum mechanics, due to Griffiths, to Omnès, and to Gell-Mann and Hartle is given. Results on the connections between decoherence, records, correlation and entropy are described. The emphasis of the presentation is on understanding the broader meaning of the conditions of consistency and d

R. J. Gooding, K. J. E. Vos, P. W. Leung

We have calculated S(q) and the single particle distribution function <n(q)> for N holes in the t - J model on a non--square sqrt{8} X sqrt{32} 16--site lattice with periodic boundary conditions; we justify the use of this lattice in compariosn to those of having the full square symmetry of the bulk. This new cluster has a high density of vec k points along

Gary Doolen, Anna Lawniczak

This article contains 39 pages of abstracts of invited and poster presentations for the FIELDS INSTITUTE FOR RESEARCH IN MATHEMATICAL SCIENCES AND NATO ADVANCED RESEARCH WORKSHOP PROGRAM ON PATTERN FORMATION and LATTICE-GAS AUTOMATA, JUNE 07-12, 1993

P. Mauas, A. Falchi

We compute a semi-empirical atmospheric model for the dMe star AD Leo, which constitutes the first model computed to match the continuum observations, as well as a wide set of chromospheric spectral lines. We find good agreement between the computed and observed spectral features, with the exception of the Ca II K line.

Susanne von Linden, Peter L. Biermann, Wolfgang J. Duschl, Harald Lesch

We demonstrate that our Galactic Center, despite little evidence for the presence of a currently active nucleus, provides insight into the feeding of AGN: The observed velocity field of molecular clouds can be interpreted as tracing out the spiralling inwards of gas in a large accretion flow towards the Galactic Center (Linden et al. 1993, Biermann et al. 19

Adrian L. Melott, Francesco Lucchin, Sabino Matarrese, Lauro Moscardini

We investigate the accuracy of the frozen--flow approximation (FFA), recently proposed by Matarrese \etal (1992), for following the nonlinear evolution of cosmological density fluctuations under gravitational instability. We compare a number of statistics between results of the FFA and nbody simulations, including those used by Melott, Pellman \& Shandarin (

V. Barger, M. S. Berger, P. Ohmann, R. J. N. Phillips

Supersymmetry (SUSY) has many well known attractions, especially in the context of Grand Unified Theories (GUTs). SUSY stabilizes scalar mass corrections (the hierarchy problem), greatly reduces the number of free parameters, facilitates gauge coupling unification, and provides a plausible candidate for cosmological dark matter. In this conference report we

A. K. Rebhan

It is shown that after a resummation of leading high-temperature contributions, a complete and gauge-independent result for the nonabelian Debye screening mass at next-to-leading order can be extracted from the static gluon propagator. In contrast to previous, incomplete results, the correction to the Debye mass is found to be logarithmically sensitive to th

P. Hasenfratz, F. Niedermayer

There exist lattice actions which give cut--off independent physical predictions even on coarse grained lattices. Rotation symmetry is restored, the spectrum becomes exact and, in addition, the classical equations have scale invariant instanton solutions. This perfect action can be made short ranged. It can be determined by combining analytical calculations

B. J. Schroers

We study the intermediate- and long-range forces between moving and spinning Skyrmions, employing two different methods. One uses a relativised product ansatz for the Skyrme fields, the other models Skyrmions as triplets of scalar dipoles. The methods lead to the same finite-dimensional Lagrangian dynamical system which may be interpreted as a point-particle

R. Cenni, A. Molinari, G. Vagradov

We discuss a relativistic theory of the atomic nuclei in the framework of the hamiltonian formalism and of the mesonic model of the nucleus. Attention is paid to the translational invariance of the theory. Our approach is centered on the concept of spectral amplitude, a function in the Dirac spinor space. We derive a Lorentz covariant equation for the latter

Dalia S. Goldwirth, Malcolm J. Perry

If string theory controls physics at the string scale, the dynamics of the early universe before the GUT era will be governed by the low-energy string equations of motion. Studying these equations for FRW spacetimes, we find that depending on the initial conditions when the stringy era starts, and on the time when it ends, there are a wide variety of qualita

Daniel Cangemi, Gerald Dunne

We present a simple unifying gauge theoretical formulation of gravitational theories in two dimensional spacetime. This formulation includes the effects of a novel matter-gravity coupling which leads to an extended de Sitter symmetry algebra on which the gauge theory is based. Contractions of this theory encompass previously studied cases.

E. Elizalde, S. Naftulin, S. D. Odintsov

Two dimensional dilaton gravity interacting with a four-fermion model and scalars is investigated, all the coefficients of the Lagrangian being arbitrary functions of the dilaton field. The one-loop covariant effective action for 2D dilaton gravity with Majorana spinors (including the four-fermion interaction) is obtained, and the technical problems which ap

E. Elizalde, S. D. Odintsov

The effective potential which describes the conformal dynamics of quantum gravity with torsion is discussed. The phase transitions induced by the combination of torsion and curvature are investigated. The mechanism for fixing the vacuum expectation values of the metric and torsion is presented.

K. Sfetsos, A. A. Tseytlin

We construct new heterotic string backgrounds which are analogous to superstring solutions corresponding to coset models but are not simply the `embeddings&#39;of the latter. They are described by the (1,0) supersymmetric extension of the $G/H$ chiral gauged WZNW models. The `chiral gauged&#39; WZNW action differs from the standard gauged WZNW action by the

Raiko P. Zaikov

The Chern-Simons membranes and in general the Chern-Simons p-branes moving in $D$-dimensional target space admit an infinite set of secondary constraints. With respect to the Poisson bracket these constraints form a closed algebra which contains classical \ $W_{1+\infty }$ \ algebra in $p$-dimensions as a subalgebra. Corresponding gauged theory in the phase-

Raiko P. Zaikov

The higher spin symmetry for both Dirac and Majorana massless free fermionic field models are considered. An infinite Lie algebra which is a linear realization of the higher spin extension of the cross products of the Virasoro and affine Kac-Moody algebras is obtained. The corresponding current algebra is closed which is not the case of annalogous current al

J. Hallin

We consider $SU(N)$ Yang-Mills on a circle (cylindrical space-time) and quantize the eigenvalues of the holonomy. In this way the Mandelstam identities associated with the holonomy are trivially solved. Furthermore we indicate that there are exactly two physically inequivalent representations of the algebra of gauge-invariant operators, resulting in differen

Pietro Donatis, Roberto Iengo

We compare the vortex-like solutions of two different theories in (2+1) dimensions. In the first a nonrelativistic field self-interacts through a Chern-Simons gauge connection. It is $P$ and $T$ violating. The second is the standard Maxwell scalar electrodynamics. We show that for specific values of some parameters the same vortex-configurations provide solu

T. Wettig, A. D. Jackson

We construct a simple multicomponent lattice gas model in one dimension in which each site can either be empty or occupied by at most one particle of any one of $D$ species. Particles interact with a nearest neighbor interaction which depends on the species involved. This model is capable of reproducing the relations between factorial moments observed in hig

R. V. Gavai, R. M. Godbole

Nuclear gluon densities are of great importance to the physics of relativistic heavy ion collisions, in particular, in assessing the origin of $J/ψ$-suppression. We describe our attempts to distinguish various models of the gluonic EMC-effect, using the existing $J/ψ$-production data in proton-nucleus collisions. We find that no model is capable of explainin

V. Barone, M. Genovese, N. N. Nikolaev, E. Predazzi

We show that there is no real conflict between the two determinations of the strange sea density from the opposite--sign dimuon production and from the difference of the $F_2$ structure functions measured in neutrino and muon deep inelastic scattering. Once non universal sea parton densities are introduced, which take into account the effects of different ma

Bengt-Åke Lindholm

We investigate the prospects of an extra global symmetry, added to the Standard Model in the context of baryogenesis. The $PQ$ symmetry is studied as an example. We show that the hadronic axion provides a protection of the B-asymmetry even if $B-L$=0 and that there are no limits on the neutrino masses. It is also shown that there is a crucial difference betw

Atushi Ishikawa, Toshiki Isse

The stability of the minisuperspace model of the early universe is studied by solving the Wheeler-DeWitt equation numerically. We consider a system of Einstein gravity with a scalar field. When we solve the Wheeler-DeWitt equation, we pick up some inhomogeneous wave modes from the infinite number of modes adequately: degrees of freedom of the superspace are

Gregory A. Burnett

The closed-universe recollapse conjecture is studied for the spherically symmetric spacetimes. It is proven that there exists an upper bound to the lengths of timelike curves in any Tolman spacetime that possesses $S^3$ Cauchy surfaces and whose energy density is positive. Furthermore, an explicit bound is constructed from the initial data for such a spaceti

Carlo Rovelli, Lee Smolin

A quantum hamiltonian which evolves the gravitational field according to time as measured by constant surfaces of a scalar field is defined through a regularization procedure based on the loop representation, and is shown to be finite and diffeomorphism invariant. The problem of constructing this hamiltonian is reduced to a combinatorial and algebraic proble

A. V. Balatsky

The superconducting instability in a non-Fermi liquid in $ d>1$ is considered. For a particular form of the single particle spectral function with homogeneous scaling $A(Λk, Λω) = Λ^α A(k, ω)$ it is shown that the pair susceptibility is also a scaling function of temperature with power defined by $α$. We find three different regimes depending on the scaling

Peter Orland

The $2+1$-dimensional quantum dimer model on a square lattice, proposed by Rokhsar and Kivelson as a theory of layered superconductivity, is shown to be equivalent to a many-body theory of free, transversely oscillating strings obeying Fermi statistics. A Jordan-Wigner construction for string field operators is presented. Topological defects are shown to be

Luis Huerta, Jorge Zanelli

A generalization of the Jordan-Wigner transformation to three (or higher) dimensions is constructed. The nonlocal mapping of spin to fermionic variables is expressed as a gauge transformation with topological charge equal to one. The resulting fermionic theory is minimally coupled to a nonabelian gauge field in a spontaneously broken phase containing monopol

Ramesh Narayan, Tsvi Piran

Following the discovery by Quashnock and Lamb (1993) of an apparent excess of $γ$-ray burst pairs with small angular separations, we reanalyze the angular distribution of the bursts in the BATSE catalogue. We find that in addition to an excess of close pairs, there is also a comparable excess of antipodal bursts, i.e pairs of bursts separated by about 180 de

J. M. Carlson, J. S. Langer, B. E. Shaw

We present an overview of our ongoing studies of the rich dynamical behavior of the uniform, deterministic Burridge--Knopoff model of an earthquake fault. We discuss the behavior of the model in the context of current questions in seismology. Some of the topics considered include: (1) basic properties of the model, such as the magnitude vs. frequency distrib

Palash B. Pal, Utpal Sarkar

In unification models based on SU(15) or SU(16), baryon number is part of the gauge symmetry, broken spontaneously. In such models, we discuss various scenarios of important baryon number violating processes like proton decay and neutron-antineutron oscillation. Our analysis depends on the effective operator method, and covers many variations of symmetry bre

Bo-Qiang Ma, Qi-Ren Zhang, D. H. Rischke, W. Greiner

We study a thermodynamically consistent implementation of the nucleon volume in the mean field theory, and find that this volume has large consequences on the properties of hadronic matter under extreme conditions such as in astrophysical objects and high energy heavy-ion collisions. It is shown that we can reproduce the critical temperature $T_{c}\simeq 200

Stephen P. Martin, Michael T. Vaughn

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 in the modified minimal subtraction sche

A. S. Rinat, M. F. Taragin

We study Final State Interaction effects (FSI) in inclusive electron scattering of several GeV from nuclear matter. We consider separately the cases of &#39;elastic&#39; and &#39;inelastic&#39; knockout of respectively a nucleon and a non-nucleonic particle. For the former category FSI have been calculated, using the first cumulant approximation of a relativ

J. A. Dixon, R. Minasian, J. Rahmfeld

We examine the BRS cohomology of chiral matter in $N=1$, $D=4$ supersymmetry to determine a general form of composite superfield operators which can suffer from supersymmetry anomalies. Composite superfield operators $\Y_{(a,b)}$ are products of the elementary chiral superfields $S$ and $\ov S$ and the derivative operators $D_\a$, $\ov D_{\dot \b}$ and $\pa_

M. Koseki, M. Sato, R. Endo

We provide a BRST symmetric version of Yokoyama&#39;s Type I gaugeon formalism for quantum electrodynamics; the similar theory by Izawa can be considered as a BRST symmetrized Type II theory. With the help of the BRST symmetry, Yokoyama&#39;s physical subsidiary conditions are replaced by the Kugo-Ojima type condition. As a result, the formalism becomes appl

Avinash Dhar

We discuss the interpertation of the $c=1$ matrix model as two-dimensional string theory in a dilaton-black hole background. The nonperturbative formulation of $c=1$ matrix model in terms of an integrable model of nonrelativistic fermions enables us to study the quantum fate of the classical black hole singularity. We find that the classical singularity is w

N. Aizawa, H. -T. Sato

We discuss quantum deformation of the affine transformation algebra. It is shown that the quantum algebra has a non-cocommutative Hopf algebra structure, simple realizations and quantum tensor operators.

M. A. van Eijck, C. R. Stephens, Ch. G. van Weert

We present a one-loop calculation of a gauge invariant QCD beta function. Using both momentum and temperature renormalization group equations we investigate the running coupling in the magnetic sector as a function of temperature and momentum scale. At fixed momentum scale we find that, in contrast to $λϕ^4$ or QED, high-temperature QCD is strongly coupled,

Benjamin Grinstein

We observe that quantities like (f_{B_s}/f_B) / (f_{D_s} /f_D) are predicted to be unity both by heavy quark and by light quark flavor symmetries. Hence, the deviation from the symmetry prediction must be simultaneously small in both symmetry breaking parameters, i.e., order of the ratio of light to heavy quarks masses. We estimate the size of the correction

Darwin Chang, Jiang Liu, Palash B. Pal

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 $ν\to ν&#39; + \mbox{Majoron}$ in the simplest singlet Majoron model. It is shown that 1-loop contributions can be

Michael A. Earnshaw, Margaret James

Vortex solutions in the two Higgs doublet electroweak model are constructed, and their stability to small perturbations is studied. The most general perturbation is decomposed into angular momentum modes, the least stable mode is identified, and the linearised energy change of the vortex under this perturbation is calculated numerically for various choices o

J. A. Caballero, T. W. Donnelly, G. I. Poulis, E. Garrido

Coincidence reactions of the type $\svec{A}(\svec{e},e&#39;N)B$ involving the scattering of polarized electrons from deformed polarized targets are discussed within the context of the plane--wave impulse approximation. A general expression for the polarized spectral function for transitions leaving the residual nucleus in discrete states is presented. Genera

N. Chepilko, A. Kobushkin, A. Syamtomov

Soliton solutions with cylindrical symmetry are investigated within the nonlinear $σ$-model disregarding the Skyrme-stabilization term. The solitons are stabilized by quantization of collective breathing mode and collapse in the $\hbar \to 0$ limit. It is shown that for such stabilization mechanism the model, apart from solitons with integer topological numb

Octavio Obregon, Jorge Pullin, Michael P. Ryan

We find a supersymmetrization of the Bianchi IX cosmology in terms of Ashtekar&#39;s new variables. This provides a framework for connecting the recent results of Graham and those of Ryan and Moncrief for quantum states of this model. These states are also related with the states obtained particularizing supergravity for a minisuperspace. Implications for th

Caren Marzban, Raju Viswanathan

Neural networks with synaptic weights constructed according to the weighted Hebb rule, a variant of the familiar Hebb rule, are studied in the presence of noise(finite temperature), when the number of stored patterns is finite and in the limit that the number of neurons $N\rightarrow \infty$. The fact that different patterns enter the synaptic rule with diff

Fabian H. L. Essler, Vladimir E. Korepin

We consider the one-dimensional Hubbard model at half filling. We show that both excitation spectrum and S-matrix are determined by the SO(4) symmetry of the model. The complete set of excitations is given by the scattering states four elementary excitations, which form the fundamental representation of SO(4). We evaluate the exact S-matrix, which satisfies

Chung-Pei Ma, Edmund Bertschinger

This paper presents a general-relativistic N-body technique for evolving the phase space distribution of massive neutrinos in linear perturbation theory. The method provides a much more accurate sampling of the neutrino phase space for the HDM initial conditions of N-body simulations in a cold+hot dark matter universe than previous work. Instead of directly

Kevin Krisciunas

In this paper we discuss four early F-type variable stars whose periods are an order of magnitude slower than known pulsators of comparable luminosity. They cannot be stars undergoing simple radial pulsations. For one or more of these stars we can discount the possibility that the variability is due to rotational modulation of star spots, interactions with (

Marco Bruni, Kamilla Piotrkowska

Flat and open universe models are considered, containing a mixture of cold matter (dust) and radiation interacting only through gravity, with the aim of studying their stability with respect to linear scalar perturbations. To this end the perturbed universe is considered as a dynamical system, described by coupled differential equations for a gauge\hs invari

Shaun Cole, Karl B. Fisher, David H. Weinberg

The peculiar velocities of galaxies distort the pattern of galaxy clustering in redshift space, making the redshift space power spectrum anisotropic. In the linear regime, the strength of this distortion depends only on the ratio $β\equiv f(Ω)/b \approx Ω^{0.6}/b$, where $Ω$ is the cosmological density parameter and $b$ is the bias parameter. We derive a lin

Paolo Catelan, Lauro Moscardini

We discuss the non--linear growth of the excess kurtosis parameter of the smoothed density fluctuation field $δ$, $S_4\equiv[\lanδ^{\,4}\ran-3\lanδ^{\,2}\ran^2]/ \lanδ^{\,2}\ran^3$ in an Einstein--de Sitter universe. We assume Gaussian primordial density fluctuations with scale--free power spectrum $P(k)\propto k^{\,n}$ and analyze the dependence of $S_4$ on

Asher Yahalom Joseph Katz, Shogo Inagaki

We analyze stability conditions of &#34;Maclaurin flows&#34; (self-gravitating, barotropic, two dimensional, stationary streams moving in closed loops around a point) by minimizing their energy, subject to fixing all the constants of the motion including mass and circulations. Necessary and sufficient conditions of stability are obtained when gyroscopic term

C. R. Hagen

Some recent work has attempted to show that the singular solutions which are known to occur in the Dirac description of spin-1/2 Aharonov-Bohm scattering can be eliminated by the inclusion of strongly repulsive potentials inside the flux tube. It is shown here that these calculations are generally unreliable since they necessarily require potentials which le

H. J. de Vega

The formulation and resolution of integrable lattice statistical models in a quantum group covariant way is the subject of this review. The Bethe Ansatz turns to be remarkably useful to implement quantum group symmetries and to provide quantum group representations even when $q$ is a root of unity. We start by solving the six-vertex model with fixed boundary

G. S. Bali, J. Fingberg, U. M. Heller, F. Karsch

A detailed investigation of the temperature dependence of the spatial string tension $σ_s$ in $SU(2)$ gauge theory is presented. A sustained performance of 3~GFLOPS on a 64K Connection Machine CM-2 equivalent has been achieved. Scaling of $σ_s$ between $β=2.5115$ and $β=2.74$, on large lattices, is demonstrated. Below the critical temperature, $T_c$, $σ_s$ r

D. B. Ion, V. Topor Pop, C. Petrascu, V. Popa

The scaling of the diffraction peak in antiproton--proton scattering has been investigated from near threshold up to $3\,\,\, GeV/c$ laboratory momenta.It was shown that the scaling of the differential cross sections are evidentiated with a surprising accuracy not only at high energies,but also at very low ones(e.q. $p_{LAB}=0.1--0.5\,\,\, GeV/c$),beyond the