August 1995 arXiv papers — page 5

Valery A. Khoze, Torbjorn Sjostrand

The process $\ee \to \W^+\W^- \to \f_1 \fbar_2 \, \f_3 \fbar_4$ contains charges in the initial, intermediate and final stages. This gives a rich selection of possible QED interconnection effects. Coulomb interaction is the simplest of these, and can thus be used to explore consequences. We study a number of experimental observables, with emphasis on those r

U. A. yajnik

The realisation that the electroweak anomaly can induce significant baryon number violation at high temperature and that the standard models of particle physics and cosmology contain all the ingredients needed for baryogenesis has led to vigourous search for viable models. The conclusions so far are that the Standard Model of particle physics cannot produce

Susmita Bhowmik Duari, U. A. Yajnik

Baryogenesis at the electroweak scale depends on divers but identifiable details of bubble wall dynamics and the particle physics. We show that inclusion of the dynamics of relative phase in two-Higgs-doublet model (2HDM) enhances the adiabatic order of the mechanism proposed by McLerran-Shaposhnikov-Turok-Voloshin where the scalar-scalar-vector triangle dia

Tao Huang, Shan Jin, Da-Hua Zhang, Kuang-Ta Chao

On the basis of the results of $ξ(2230)\rightarrowπ^{+}π^{-}, p\bar{p}$ and $K\bar{K}$, measured by the BES Collaboration in radiative J/$ψ$ decays, combined with the upper limit of Br($ξ\rightarrow p\bar{p}$)Br($ξ\rightarrow K\bar{K}$), measured by PS185 experiment, we argue that the distinctive properties of $ξ$(2230), the flavor-symmetric decays and the n

Pierre van Baal

In previous work constant magnetic field strength solutions for SU(2) gauge theory on a torus were found, which somewhat surprisingly turned out to be classically stable. This was called marginal stability, as moving along one of its zero-modes, two of the stable modes turn unstable. Here we investigate the stability under quantum fluctuations in the domain

J. D. Canosa, H. R. Fiebig

The residual interaction for a meson-meson system is computed utilizing the cumulant, or cluster, expansion of the momentum-space time correlation matrix. The cumulant expansion serves to define asymptotic, or free, meson-meson operators. The definition of an effective interaction is then based on a comparison of the full (interacting) and the free (noninter

G. Sardanashvily

In gravitation theory, a fermion field must be regarded only in a pair with a certain tetrad gravitational field. These pairs can be represented by sections of the composite spinor bundle $S\to\Si\to X^4$ where values of gravitational fields play the role of parameter coordinates, besides the familiar world coordinates.

Matthew J. Reilly, A. G. Rojo

We consider a model of Raman scattering for a two--dimensional $S=1/2$ Heisenberg Anti-Ferromagnet which includes a {\it dynamical} spin--phonon interaction. We observe a broadening of the line shape due to increased coupling with excited high--energy spin states. Our results are close to a model of random static exchange interactions, first introduced in th

S. E. Lofland, S. M. Bhagat, C. Kwon, M. C. Robson

We report the first observation of spin wave resonances in 110 nm thick films of LBMO. The spin wave stiffness follows $D$ = 47 (1 - 3 \times 10$_{-7}$ $T^{5/2}$) meV${Å_2}$.

Michael C. Martin, G. Shirane, Y. Endoh, K. Hirota

Neutron scattering studies on a single crystal of the highly-correlated electron system, La1-xSrxMnO3 with x~0.3, have been carried out elucidating both the spin and lattice dynamics of this metallic ferromagnet. We report a large measured value of the spin wave stiffness constant, which directly shows that the electron transfer energy of the d band is large

Andrew J. Dolgert, S. John Di Bartolo, Alan T. Dorsey

The superheated Meissner state in type-I superconductors is studied both analytically and numerically within the framework of Ginzburg-Landau theory. Using the method of matched asymptotic expansions we have developed a systematic expansion for the solutions of the Ginzburg-Landau equations in the limit of small $κ$, and have determined the maximum superheat

Yuli V. Nazarov

We developed a microscopic approach to calculate the sample-to-sample fluctuations of transmission distribution in disordered conductors. This bridges between Green's function and random matrix theories of quantum transport. The results obtained show that the correlations of transmission eigenvalues obey universal Dyson statistics at small separations be

A. M. Janner, R. Eder, B. Koopmans, H. T. Jonkman

The electric dipole forbidden T_1g excitonic state of solid C_60 at omega=1.81 eV can be probed with a Second-Harmonic Generation (SHG) experiment. We show that the SHG line shape depends strongly on the degree of rotational order. We observe a splitting into two peaks below the rotational ordering phase transition temperature of 260 K. The origin of this sp

V. N. Muthukumar, Roser Valenti, Claudius Gros

This manuscript deals with the question "How does light couple to an antiferromagnetic order parameter"? For that we develop a microscopic model that explains the non-reciprocal optical effects in centrosymmetric Cr_2 O_3. It is shown that light can couple {\em directly} to the antiferromagnetic order parameter. This coupling is mediated by the spin-

N. Zacharias, C. de Vegt, L. Winter, K. J. Johnston

In this pilot investigation, precise optical positions in the FK5 system are presented for a set of 16 compact extragalactic radio sources, which will be part of the future radio--optical reference frame. The 0.9 m KPNO and CTIO telescopes equipped with 2K CCD's have been used for this project. The astrometric properties of these instruments are investig

L. L. R. Williams, P. Saha

We argue that individual images in multiple-image QSOs could easily have substructure at the level of $0.1''$ (i.e., unresolvable even with HST); microlensing within such substructure would cause centroid shifts, observable even from the ground as pseudo proper motions. We present a model of the four-image system 2237+0305 in which Image B shows such

J. S. Bagla

Alignment of velocity and acceleration before shell crossing, and later misalignment are used to define velocity contrast, an indicator of dynamical state of matter undergoing gravitational collapse. We use this to study bias in clustering properties of dynamically nonlinear mass.

Eliyahu Greitzer

Changes of variables giving the dual model are constructed explicitly for sigma-models without isotropy. In particular, the jacobian is calculated to give the known results. The global aspects of the abelian case as well as some of those of the cases where the isometry group is simply connected are considered. Considering the anomalous case, we infer by a co

M. Ichioka, N. Enomoto, N. Hayashi, K. Machida

Vortex structure of $d_{x^2-y^2}$-wave superconductors is microscopically analyzed in the framework of the quasi-classical Eilenberger equations. If the pairing interaction contains an $s$-wave ($d_{xy}$-wave) component in addition to a $d_{x^2-y^2}$-wave component, the $s$-wave ($d_{xy}$-wave) component of the order parameter is necessarily induced around a

Dan Maoz

I measure the V-I color distribution of two samples of radio-selected quasars. Quasars from one sample are projected on the sky within 1 degree of a rich foreground Abell cluster of galaxies, while quasars from the other sample are more than 3 degrees from any such cluster . There is no significant difference between the color distributions of the two sample

Donald Q. Lamb, Tomasz Bulik, Paolo S. Coppi

We describe observational evidence and theoretical calculations which support the high velocity neutron star model of gamma-ray bursts. We estimate the energetic requirements in this model, and discuss possible energy sources. we also consider radiative processes involved in the bursts.

Tomasz Bulik, Donald Q. Lamb

We investigate the viability of the Galactic halo model of $γ$-ray bursts by calculating the spatial distribution of neutron stars born with high velocities in the Galactic disk, and comparing the resulting brightness and angular distribution with the BATSE data. We find that the Galactic halo model can reproduce the BATSE peak flux and angular distribution

Sangjin Lee, Angela Olinto, Guenter Sigl

The strength and spectrum of the extragalactic magnetic field are still unknown. Its measurement would help answer the question of whether galactic fields are purely a primordial relic or were dynamically enhanced from a much smaller cosmological seed field. In this letter, we show that the composition, spectrum, and directional distribution of extragalactic

M. J. Duff, James T. Liu, J. Rahmfeld

In six spacetime dimensions, the heterotic string is dual to a Type $IIA$ string. On further toroidal compactification to four spacetime dimensions, the heterotic string acquires an $SL(2,\BbbZ)_S$ strong/weak coupling duality and an $SL(2,\BbbZ)_T \times SL(2,\BbbZ)_U$ target space duality acting on the dilaton/axion, complex Kahler form and the complex str

Herbert Balasin, Herbert Nachbagauer

We generalize previous work \cite{BaNa3} on the ultrarelativistic limit of the Kerr-geometry by lifting the restriction on boosting along the axis of symmetry.

Kazuhiro Yamamoto, Emory F. Bunn

Motivated by recent studies of the one-bubble inflationary scenario, simple open cold dark matter models are tested for consistency with cosmological observations. The initial perturbation spectrum is derived by solving for the evolution of fluctuations in an open inflationary stage. A likelihood analysis is performed for the Cosmic Microwave Background anis

C. P. Burgess, R. C. Myers, F. Quevedo

Some recent results on the applications of duality (and related) transformations to general four-dimensional, spherically symmetric, asymptotically flat and time-independent string configurations are summarized. Two classes of results have been obtained. First, these transformations are used to generate the general such solution to the lowest-order field equ

Subir Sachdev

We study the finite temperature crossovers in the vicinity of a zero temperature quantum phase transition. The universal crossover functions are observables of a continuum quantum field theory. Particular attention is focussed on the high temperature limit of the continuum field theory, the so-called ``quantum-critical'' region. Basic features of cro

E. Bergshoeff, H. J. Boonstra, T. Ortin

We show how a solitonic ``magnetically'' charged $p$-brane solution of a given supergravity theory, with the magnetic charge carried by an antisymmetric tensor gauge field, can be generalized to a dyonic solution. We discuss the cases of ten-dimensional and eleven-dimensional supergravity in more detail and a new dyonic five-brane solution in ten dim

Julian J. -L. Ting, Michel Peyrard

Collective coordinate and direct numerical integration methods are applied to the analysis of a one-dimensional DNA model. A modification of the coupling constant in an extended region is found to be less selective towards the breather it can trap than an isolated impurity. Therefore it provides a possible physical mechanism for the effect of an enzyme on DN

S. P. Plunkett, M. Delaney, B. McBreen, K. J. Hurley

A small air shower array operating over many years has been used to search for ultra-high energy (UHE) gamma radiation ($\geq 50$ TeV) associated with gamma-ray bursts (GRBs) detected by the BATSE instrument on the Compton Gamma-Ray Observatory (CGRO). Upper limits for a one minute interval after each burst are presented for seven GRBs located with zenith an

Euan J. Squires

A derivation of the Bohm model, and some general comments about it, are given. A modification of the model which is formally local and Lorentz-invariant is introduced, and its properties studied for a simple experiment.

Anna Okopińska

The O(N) symmetric scalar quantum field theory with λΦ^4 interaction is discussed in the Gaussian approximation. It is shown that the Goldstone theorem is fulfilled for arbitrary N.

H. Endres, R. M. Noack, W. Hanke, D. Poilblanc

Using grand canonical Quantum Monte Carlo (QMC) simulations combined with Maximum Entropy analytic continuation, as well as analytical methods, we examine the one- and two-particle dynamical properties of the Hubbard model on two coupled chains at half-filling. The one-particle spectral weight function, $A({\bf k},ω)$, undergoes a qualitative change with int

K. Kirsten, E. Elizalde

We review the definition of the Casimir energy steming naturally from the concept of functional determinant through the zeta function prescription. This is done by considering the theory at finite temperature and by defining then the Casimir energy as its energy in the limit $T\to 0$. The ambiguity in the coefficient $C_{d/2}$ is understood to be a result of

E. Elizalde

Owing to its lack of derivability, the dissipative anomaly operator appearing in the theory of turbulence without pressure recently proposed by Polyakov appears to be quite elusive. In particular, we give arguments that seem to lead to the conclusion that an anomaly in the first equation of the sequence of conservation laws cannot be {\it a priori} excluded.

Re'em Sari, Tsvi Piran

We calculate the hydrodynamic time scales for a spherical ultra-relativistic shell that is decelerated by the ISM and discuss the possible relations between these time scales and the observed temporal structure in $\gamma$-ray bursts. We suggest that the bursts' duration is related to the deceleration time, the variability is related to the ISM inhomogeneiti

Merle Michael Robinson, Jacek Ziabicki

We study quark and lepton mass matrix textures in a model containing an additional $U(1)_X$ gauge symmetry with origins in string compactification. The $U(1)_X$ symmetry is broken near the string scale, and we assume that the anomalies are canceled by the Green-Schwarz mechanism. We also assume that fermion mass matrices are generated by an additional scalar

A. N. Vall, S. E. Korenblit, V. M. Leviant, A. V. Sinitskaya

Vacuum structure, one-particle excitations' spectra and bound states of these excitations are studied in frame of non-relativistic quantum field model with current $\times$ current type interaction. Hidden symmetry of the model is found. It could be broken or exact depending on the coupling constant value. The effect of "piercing" vacuum , genera

A. Valcarce, F. Fernandez, E. Moro, H. Garcilazo

We analyze the possible existence of a resonance in the $J^P=0^-$ channel with isospin two by means of nucleon-$Δ$ interactions based on the constituent quark model. We solve the bound state and the scattering problem using two different potentials, a local and a non-local one. The non-local potential results to be the more attractive, although not enough to

R. Bilger, H. Clement, A. Denig, K. Fohl

The KARMEN collaboration has reported the possible observation of a hitherto unknown neutral and weakly interacting particle x, which is produced in the decay pi -> mu + x with a mass m(x) = 33.9 MeV. We have searched for this hypothetical decay branch by studying muons from pion decay in flight with the LEPS spectrometer at the piE3 channel at PSI and find

U. Bunke, M. Olbrich

We prove the finiteness of the cohomology of torsion-free lattices in a semisimple Lie group of real rank one with coefficients in the distribution vector globalization of Harish-Chandra modules. The cohomology is expressed in terms of automorphic and cusp forms. We also consider the Lie-algebra cohomology of these globalizations for the nilpotent part of th

M. Legare

The reduction by symmetry of the linear system of the self-dual Yang-Mills equations in four-dimensions under representatives of the conjugacy classes of subgroups of the connected part to the identity of the corresponding Euclidean group under itself is carried out. Only subgroups leading to systems of differential equations nonequivalent to conditions of z

Justin Hayward

A general homogeneous two dimensional dilaton gravity model considered recently by Lemos and S\` a, is given quantum matter Polyakov corrections and is solved numerically for several static, equilibrium scenarii. Classically the dilaton field ranges the whole real line, whereas in the semi-classical theory, with the usual definition, it is always below a cer

David I Olive

This talk, given at several conferences and meetings, explains the background leading to the formulation of the exact electromagnetic duality conjecture believed to be valid in N=4 supersymmetric SU(2) gauge theory.

Klaus Kirstem, Guido Cognola

The zeta function associated with higher-spin fields on the Euclidean $4$-ball is investigated. The leading coefficients of the corresponding heat-kernel expansion are given explicitly and the zeta functional determinant is calculated. For fermionic fields the determinant is shown to differ for local and spectral boundary conditions.

E. J. Chun, A. S. Yoshipura, A. Yu. Smirnov

The existence of a light singlet fermion mixed with the electron neutrino is hinted by the simultaneous explanation of various neutrino anomalies. We show that supersymmetry can provide a natural framework for the existence and the desired properties of such a fermion. Quasi Goldstone fermions (QGF) of spontaneously broken global symmetries like the Peccei-Q

Abdellatif Abada, H. Weigel, R. Alkofer, H. Reinhardt

We investigated the form factors of the nucleon associated with the nonet vector current in the framework of the generalized Yabu--Ando approach to the chiral soliton of the Nambu--Jona--Lasinio model. We introduce a variational parameter to improve the predictions for the baryon mass splittings and, in addition, we take into account $1/N_c$ rotational corre

L. Ya. Glozman, D. O. Riska

The constituent quark model can explain the strong selectivity of the $Nη$ decay branching ratios of the nucleon resonances if the fine structure interaction between the constituent quarks is described in terms of Goldstone boson exchange. This chiral quark model predicts that the resonances $N(1535)$, $N(1710)$, $Λ(1670)$, $Σ(1750)$, which have mixed flavor

R. P. Springer

The discrepancies found between S-wave and P-wave fits for hyperon decays are reinvestigated using the heavy baryon chiral Lagrangian formalism. The agreement is found to improve through the inclusion of previously omitted diagrams. The S-waves are unaffected by this, but the P-wave predictions are modified. A correlated fit to the chiral parameters is perfo

P. Maris

The standard approximations of the Dyson--Schwinger equation lead to complex singularities of the fermion propagator. In three-dimensional QED one can show that this phenomenon might be related to confinement: a confining potential leads to mass-like singularities at complex momenta, and thus to the absence of a mass singularity on the real timelike axis. Th

Charles W. Misner

Omitting the motivations and historical connections, and also the detailed calculations, I state succinctly the principles that determine the relativistic idealization of a GPS system. These determine the results that Ashby presents in his tutorial.

Walter Simon

We show that the Riemannian Kerr solutions are the only Riemannian, Ricci-flat and asymptotically flat ${\rm C}^{2}$-metrics $g_{μν}$ on a 4-dimensional complete manifold ${\cal M}$ of topology ${\rm R}^{2} \times {\rm S}^{2}$ which have (at least) a 1-parameter group of periodic isometries with only isolated fixed points ("nuts") and with orbits of

E. Elizalde, S. D. Odintsov

Renormalization group techniques are used in order to obtain the improved non-local gravitational effective action corresponding to any asymptotically free GUT, up to invariants which are quadratic on the curvature. The corresponding non-local gravitational equations are written down, both for the case of asymptotically free GUTs and also for quantum R$^2$-g

L. P. Rokhinson, B. Su, V. J. Goldman

The diagonal conductivity $σ_{xx}$ was measured in the Corbino geometry in both integer and fractional quantum Hall effect (QHE). We find that peak values of $σ_{xx}$ are approximately equal for transitions in a wide range of integer filling factors $3<ν<16$, as expected in scaling theories of QHE. This fact allows us to compare peak values in the integer an

H. T. C. Stoof, M. Houbiers, C. A. Sackett, R. G. Hulet

We study the prospects for observing superfluidity in a spin-polarized atomic gas of $^6$Li atoms, using state-of-the-art interatomic potentials. We determine the spinodal line and show that a BCS transition to the superfluid state can indeed occur in the (meta)stable region of the phase diagram if the densities are sufficiently low. Moreover, for a total de

X. Zotos, P. Prelovsek

Using numerical diagonalization techniques we analyze the finite temperature/frequency conductance of a one dimensional model of interacting spinless fermions. Depending on the interaction, the observed finite temperature charge stiffness and low frequency conductance indicate a fundamental difference between integrable and non-integrable cases. The integrab

V. P. Gusynin, V. M. Loktev, I. A. Shovkovy

Proceeding from the simplest field theoretical model of 2D metal, the normal phase Green functions of the weakly interacting fermions and the order parameter fluctuations (responsible for the attraction between fermions) are obtained. It is shown that taking into consideration the fluctuations mentioned leads to a considerable reduction of the fermion wave f

H. T. C. Stoof, K. Mullen, M. Wallin, S. M. Girvin

We derive the hydrodynamic equations for the supersolid and superhexatic phases of a neutral two-dimensional Bose fluid. We find, assuming that the normal part of the fluid is clamped to an underlying substrate, that both phases can sustain third-sound modes and that in the supersolid phase there are additional modes due to the superfluid motion of point def

Sungchul Kwon, Hyunggyu Park

We investigate the phase diagram of branching annihilating random walks with one and two offsprings in one dimension. A walker can hop to a nearest neighbor site or branch with one or two offsprings with relative ratio. Two walkers annihilate immediately when they meet. In general, this model exhibits a continuous phase transition from an active state into t

Hyunggyu Park, Heungwon Park

We study a monomer-dimer model with repulsive interactions between the same species in one dimension. With infinitely strong interactions the model exhibits a continuous transition from a reactive phase to an inactive phase with two equivalent absorbing states. Static and dynamic Monte Carlo simulations show that the critical behavior at the transition is di

Heungwon Park, Mann Ho Kim, Hyunggyu Park

We study the dynamic scaling behavior of a monomer-dimer model with repulsive interactions between the same species in one dimension. With infinitely strong interactions the model exhibits a continuous transition from a reactive phase to an inactive phase with two equivalent absorbing states. This transition does not belong to the conventional directed perco

R. C. Nichol, A. J. Connolly

In this paper, we present the results of comparing the angular distribution of Abell clusters with Galactic HI measurements. For most subsamples of clusters considered, their positions on the sky appear to be anti-correlated with respect to the distribution of HI column densities. The statistical significance of these observed anti-correlations is a function

E. S. Cheng, D. A. Cottingham, D. J. Fixsen, C. A. Inman

The second flight of the Medium Scale Anisotropy Measurement (MSAM1-94) observed the same field as the first flight (MSAM1-92) to confirm our earlier measurement of cosmic microwave background radiation (CMBR) anisotropy. This instrument chops a 30\arcmin\ beam in a 3 position pattern with a throw of $\pm40\arcmin$, and simultaneously measures single and dou

Sean T. Scully, Michel Casse, Keith A. Olive, D. N. Schramm

Determinations of the \he3 concentrations in Galactic matter serve to impose interesting and important constraints both on cosmological models and on models of Galactic chemical evolution. At present, observations of \he3 in the solar system and in the interstellar medium today suggest that the \he3 abundance has not increased significantly over the history

Ethan T. Vishniac

Recent work on the structure of magnetic fields in a turbulent medium gives predictions for the properties of the magnetic flux tubes as a function of the Mach number and scale of the turbulence, and the resistivity and viscosity of the fluid. Here I discuss the implications of this work for accretion disks. I show that although accretion disk flux tubes are

Pavel Kroupa

We postulate that most stars are born in aggregates of binary systems which are dynamically equivalent to the `dominant mode cluster&#39;. The initial binary orbits are consitent with pre-main sequence data. Stellar masses are paired at random from the KTG(1.3) mass function. We develop a simple model which establishes the observed correlations between eccen

S. Campana, A. Parodi, L. Stella

Large light deflection angles are produced in the strong gravitational field regions around neutron stars and black holes. In the case of binary systems, part of the photons emitted from the companion star towards the collapsed object are expected to be deflected in the direction of the earth. Based on a semi-classical approach we calculate the characteristi

Ernest M. Henley

Some recent experimental and theoretical work on 1) charge symmetry-breaking, 2) parity non-conservation, and 3) searches for breaking of time reversal invariance are reviewed. The examples illustrate the uses of symmetry to learn about underlying dynamics and/or structure.

N. F. Schwabe, R. J. Elliott

Employing a recently developed technique of component weighted two particle Green&#39;s functions in the CPA of a binary substitutional alloy $A_cB_{1-c}$ we extend the existing theory of excitons in such media using a contact potential model for the interaction between electrons and holes to an approximation which interpolates correctly between the limits o

Eung Jin Chun

We consider the simplest model of $SU(3) \times SU(2) \times U(1)_Y \times U(1)_R$ gauge symmetry with one extra singlet field whose vacuum expectation value breaks the horizontal $R$-symmetry $U(1)_R$ and gives rise to Yukawa textures. The $U(1)_R$ symmetry is able to provide both acceptable fermion mass hierarchies and a natural solution to the $μ$ problem

K. J. Hurley, B. McBreen, M. Delaney, A. Britton

The time interval between successive bursts from SGR 1806-20 and the intensity of these bursts are both consistent with lognormal distributions. Monte Carlo simulations of lognormal burst models with a range of distribution parameters have been investigated. The main conclusions are that while most sources like SGR 1806-20 should be detected in a time interv

James E Lidsey, Andrew R Liddle, Edward W Kolb, Edmund J Copeland

We review the relation between the inflationary potential and the spectra of density (scalar) perturbations and gravitational waves (tensor perturbations) produced, with particular emphasis on the possibility of reconstructing the inflaton potential from observations. The spectra provide a potentially powerful test of the inflationary hypothesis; they are no

A. B. Goncharov, A. M. Levin

In this paper we introduce an elliptic analog of the Bloch-Suslin complex and prove that it (essentially) computes the weight two parts of the groups $K_2(E)$ and $K_1(E)$ for an elliptic curve $E$ over an arbitrary field $k$. Combining this with the results of Bloch and Beilinson we proved Zagier&#39;s conjecture on $L(E,2)$ for modular elliptic curves over

B. Blankleider, A. N. Kvinikhidze

We summarise the recent theoretical progress in few-body descriptions of the piNN system. Previous descriptions, both three- and four-dimensional, are shown to possess serious theoretical inconsistencies. We illustrate how three-dimensional approaches suffer from renormalisation problems, and how four-dimensional descriptions contain both overcounting and un

Leonid V. Razumov, Hans Feldmeier

Using Quantum Field Theory we derive a general formula for the double inclusive spectra of photons radiated by a system in local equilibrium. The derived expression differs significantly from the one mostly used up to now in photon intensity interferometry of heavy--ion collisions. We present a covariant expression for double inclusive spectra adapted for us

C. R. Fernandez-Pousa, J. L. Miramontes

The Poisson bracket algebra corresponding to the second Hamiltonian structure of a large class of generalized KdV and mKdV integrable hierarchies is carefully analysed. These algebras are known to have conformal properties, and their relation to $\cal W$-algebras has been previously investigated in some particular cases. The class of equations that is consid

D. Yu. Ivanov

The diffractive process $γ^*(Q^2) p\to V+X$ (where $V= ρ^0, ω, ϕ$ are the vector mesons, consisted of light quarks, $X$ represents the hadrons to that a proton dissociates) is studied. We consider the region of large momentum transfers, $|t|>>Λ^2_{QCD}$, and large energies, s. In the leading log approximation of perturbative QCD ( using BFKL equation ) the a

E. A. De Wolf, I. M. Dremin, W. Kittel

Experimental data are presented on particle correlations and fluctuations in various high-energy multiparticle collisions, with special emphasis on evidence for scaling-law evolution in small phase-space domains. The notions of intermittency and fractality as related to the above findings are described. Phenomenological and theoretical work on the subject is

C. Ahn, W. M. Koo

We construct and solve the boundary Yang-Baxter equation in the RSOS/SOS representation. We find two classes of trigonometric solutions; diagonal and non-diagonal. As a lattice model, these two classes of solutions correspond to RSOS/SOS models with fixed and free boundary spins respectively. Applied to (1+1)-dimenional quantum field theory, these solutions

Boris Feigin, Edward Frenkel

We define quantum W-algebras generalizing the results of Reshetikhin and the second author, and Shiraishi-Kubo-Awata-Odake. The quantum W-algebra associated to sl_N is an associative algebra depending on two parameters. For special values of parameters it becomes the ordinary W-algebra of sl_N, or the q-deformed classical W-algebra of sl_N. We construct free

Tomasz Brzezinski

An approach to construction of a quantum group gauge theory based on the quantum group generalisation of fibre bundles is reviewed.

A. Aghamohammadi, M. Khorrami, A. Shariati

All quantum group structures on the group GL(2) are classified. It is shown that there are only two such structures, the well known quantum groups GL$_{qp}$(2) and GL$_{hh&#39;}$(2).

A. Bianconi, S. Jeschonnek, N. N. Nikolaev, B. G. Zakharov

Are short range correlations in the ground state of the target nucleus (initial state correlations ISC)observable inexperiments on quasielastic $A(e,e&#39;p)$ scattering at large missing momentum $p_{m}$? Will the missing momentum spectrum observed at CEBAF be overwhelmed by final state interactions of the struck proton? Taking the $^{4}He$ nucleus with a re

H. Feldmeier, J. Németh, G. Papp

A saturating hamiltonian is presented in a relativistically covariant formalism. The interaction is described by scalar and vector mesons, with coupling strengths adjusted to the nuclear matter. No explicit density depe ndence is assumed. The hamiltonian is applied in a QMD calculation to determine the fragment distribution in O + Br collision at different e

Michael Dine

The holomorphy of the superpotential along with symmetries gives very strong constraints on any stringy non-perturbative effects. This observation suggests an approach to string phenomenology. (Presented at ``Strings 95&#39;&#39;, March 1995.

Andreas Bette

Using Lorentz force equation as an input a Hamiltonian mechanics on the non-projective two twistor phase space TxT is formulated. Such a construction automatically reproduces dynamics of the intrinsic classical relativistic spin. The charge appears as a dynamical variable. It is also shown that if the classical relativistic spin function on TxT vanishes, the

J. S. Dowker

Using known mode properties, the functional determinant for massless spin-half fields on the Euclidean 4-ball is calculated and shown to be different for spectral (nonlocal) and mixed (local) boundary conditions. The local result agrees with that from a conformal argument. Some higher-spin results are also given.

Andreas Bette

A short review of special relativistic dynamics describing a particle acted upon by an arbitrary conservative external force is presented. If the mass of the particle is zero and the force is central then the equations of motion turn out to be completely integrable. A well-known result. Hamiltonian flows on the twistor phase space T are constructed which, fo

S. O. Warnaar

We compute the one-dimensional configuration sums of the ABF model using the fermionic technique introduced in part I of this paper. Combined with the results of Andrews, Baxter and Forrester, we find proof of polynomial identities for finitizations of the Virasoro characters $χ_{b,a}^{(r-1,r)}(q)$ as conjectured by Melzer. In the thermodynamic limit these i

Howard Baer, Michal Brhlik

Working within the framework of the minimal supergravity model with gauge coupling unification and radiative electroweak symmetry breaking, we evaluate the cosmological relic density from lightest neutralinos produced in the early universe. Our numerical calculation is distinct in that it involves direct evaluation of neutralino annihilation cross sections u

G. Bélanger, F. Boudjema, D. London, H. Nadeau

We critically reexamine the prospects for the observation of the $ΔL=2$ lepton-number-violating process $\eeWW$ using the $e^-e^-$ option of a high-energy $e^+e^-$ collider (NLC). We find that, except in the most contrived scenarios, constraints from neutrinoless double beta decay render the process unobservable at an NLC of $\sqrt{s}<2$ TeV. Other $ΔL=2$ pr

J. T. A. Lang, J. E. Paton, A. M. Green

A first attempt to understand hadron dynamics at low energies in terms of the fundamental quark and gluon degrees of freedom incorporates the effects of the gluonic field into a potential depending only on the spatial positions of the quarks, which are considered in the infinite mass limit. A suitable framework for calculating such potentials between static

Martin Zach, Manfried Faber, Wolfgang Kainz, Peter Skala

We compare U(1) lattice gauge theory to an effective model of Maxwell and London equations. In the effective model there is only one free parameter, the London penetration depth lambda. It turns out that one can get good agreement between both models if one modifies the usual definition of magnetic monopole currents in U(1) lattice gauge theory. This compari

George Kirczenow, Brad L. Johnson

We present a mean field theory of composite fermion edge channel transport in the fractional and integer quantum Hall regimes. An expression relating the electro-chemical potentials of composite fermions at the edges of a sample to those of the corresponding electrons is obtained and a plausible form is assumed for the composite fermion Landau level energies

N. F. Schwabe, R. J. Elliott

We extend the two particle theory of disordered systems within the coherent potential approximation CPA to obtain weighted contributions to averaged two particle resolvents which arise from separate alloy components. Starting from first principles in a model of diagonal disorder and the single site approximation for a binary substitutional alloy $A_cB_{1-c}$

M. L. Plumer

A phenomenological model of the Landau type forms the basis for a study of elastic distortions near the spin-Peierls transition $T_c$ in $CuGeO_3$. The atomic displacements proposed by Hirota {\it et al.} [Phys. Rev. Lett. {\bf 73}, 736 (1994)] are accounted for by the model which includes linear coupling between $Cu$ and $O$ distortions. $Cu$ displacements

Rochus Klesse, Marcus Metzler

We investigate numerically the localization-delocalization transition in quantum Hall systems with long-range disorder potential with respect to multifractal properties. Wavefunctions at the transition energy are obtained within the framework of the generalized Chalker--Coddington network model. We determine the critical exponent $α_0$ characterizing the sca

Anne van Otterlo, Karl-Heinz Wagenblast, Reinhard Baltin, C. Bruder

We investigate the properties of strongly interacting bosons in two dimensions at zero temperature using mean-field theory, a variational Ansatz for the ground state wave function, and Monte Carlo methods. With on-site and short-range interactions a rich phase diagram is obtained. Apart from the homogeneous superfluid and Mott-insulating phases, inhomogeneou

Bruno Eckhardt, Joerg Main

We analyze within a semiclassical approximation the form factor for the fluctuations of quantum matrix elements around their classical average. We find two contributions: one is proportional to the form factor for the density of states, with an amplitude determined by the squared average of the matrix elements. The other is constant and related to the fluctu