January 1995 arXiv papers — page 3

Ashok Das, Clovis Wotzasek

We study a supersymmetric 2-dimensional harmonic oscillator which carries a representation of the general graded Lie algebra GL(2$\vert$1), formulate it on the superspace, and discuss its physical spectrum.

S. Chaudhuri, S. -wei Chung, G. Hockney, J. Lykken

We explore the use of real fermionization as a test case for understanding how specific features of phenomenological interest in the low-energy effective superpotential are realized in exact solutions to heterotic superstring theory. We present pedagogic examples of models which realize SO(10) as a level two current algebra on the world-sheet, and discuss in

Abdellatif Abada, Fabio L. Braghin, Dominique Vautherin

We calculate the isovector response function of hot nuclear matter using various effective Skyrme interactions. For Skyrme forces with a small effective mass the strength distribution is found to be nearly independent of temperature, and shows little collective effects. In contrast effective forces with an effective mass close to unity produce sizeable colle

Narcisse Randrianantoanina

Let $A$ be the disk algebra, $Ω$ be a compact Hausdorff space and $μ$ be a finite Borel measure in $Ω$. It is shown that the dual of $C(Ω,A)$ has the Dunford-Pettis Property. This proved in particular that the spaces $C(Ω,A)$ and $L^1(μ,A*)$ have the Dunford-Pettis property.

I. Bandos, P. Pasti, D. Sorokin, M. Tonin

We perform a generalization of the geometrical approach to describing extended objects for studying the doubly supersymmetric twistor--like formulation of super--p--branes. Some basic features of embedding world supersurface into target superspace specified by a geometrodynamical condition are considered. It is shown that the main attributes of the geometric

Luca LUSANNA

A review is given of the presymplectic approach to relativistic physical systems and of the determination of their Dirac's observables. After relativistic mechanics and Nambu string, the Dirac's observables of Yang-Mills theory with fermions are given for the case of massless vector bosons (like in QED). A Dirac-Yukawa-like intrinsic ultraviolet cut-

Jacques Distler, Shamit Kachru

We discuss a duality of (0,2) heterotic string vacua which implies that certain pairs of (0,2) Calabi-Yau compactifications on topologically distinct target manifolds yield identical string theories. Some complex structure moduli in one model are interpreted in the dual model as deforming the holomorphic structure of the vacuum gauge bundle (and vice versa).

Luca Mezincescu, Rafael I. Nepomechie

We begin with a review of the antiferromagnetic spin 1/2 Heisenberg chain. In particular, we show that the model has particle-like excitations with spin 1/2, and we compute the exact bulk S matrix. We then review our recent work which generalizes these results. We first consider an integrable alternating spin 1/2 - spin 1 chain. In addition to having excitat

Chungsik Song

The properties of $ρ$-mesons at finite temperature ($T$) are examined with an effective chiral lagrangian in which vector and axial-vector mesons are included as massive Yang-Mills fields of the chiral symmetry. It is shown that, at $T^2$ order, the effective mass is not changed but only the mixing effect in vector and axial-vector correlator appears.

M. A. Ivanov, T. Mizutani

We demonstrate that to calculate the self-energy of a heavy quark in the heavy quark limit (or the heavy fermion limit in what is called the Baryon Chiral Perturbation Theory), the use of standard dimensional regularization provides only the quantum limit: opposite to the heavy quark (or classical) limit that one wishes to obtain. We thus devised a standard

G. J. Gounaris, F. M. Renard, C. Verzegnassi

We establish the most general parametrization of the new physics tested by present precision measurements and possibly responsible for any deviation of the $Z\to b \bar b $ amplitude from its Standard Model result, under the assumption that it is CP symmetric and is induced by degrees of freedom which are too heavy to be ~directly produced at the future Coll

B. Alles, A. Di Giacomo, H. Panagopoulos, E. Vicari

We study the renormalization group behaviour of the topological charge density in full QCD on the lattice. We propose a way of extracting the necessary renormalization functions from Monte Carlo simulations.

Vaia Papadimitriou

We report on measurements of the Upsilon(1S), Upsilon(2S) and Upsilon(3S) differential and integrated cross sections in pp(bar) collisions at sqrt(s)=1.8 TeV. The three resonances were reconstructed through the decay Upsilon-->mu(+)mu(-). The cross section measurements are compared to theoretical models of direct bottomonium production.

J. Skarha

A next generation silicon vertex detector is planned at CDF for the 1998 Tevatron collider run with the Main Injector. The SVX~II silicon vertex detector will allow high luminosity data-taking, enable online triggering of secondary vertex production, and greatly increase the acceptance for heavy flavor physics at CDF. The design specifications, geometric lay

Luc Blanchet

This paper derives the expressions of the multipole moments of an isolated gravitating source with an accuracy corresponding to the second post-Newtonian (2-PN) approximation of general relativity. The moments are obtained by a procedure of matching of the external gravitational field of the source to the inner field, and are found to be given by integrals e

Luc Blanchet, Thibault Damour, Bala R. Iyer

Gravitational waves generated by inspiralling compact binaries are investigated to the second--post-Newtonian (2PN) approximation of general relativity. Using a recently developed 2PN-accurate wave generation formalism, we compute the gravitational waveform and associated energy loss rate from a binary system of point-masses moving on a quasi-circular orbit.

Michael Frank, Evgenij V. Troitsky

The main goal of the present paper is to generalize the results of~\cite{TroLNM,TroBoch} in the following way: To be able to define $K_0(A)ø\C$-valued Lefschetz numbers of the first type of an endomorphism $V$ on a C*-elliptic complex one usually assumes that $V=T_g$ for some representation $T_g$ of a compact group $G$ on the C*-elliptic complex. We try to r

J. K. Beem, R. J. Low, P. E. Parker

We continue our study of the space of geodesics of a manifold with linear connection. We obtain sufficient conditions for a product to have a space of geodesics which is a manifold. We investigate the relationship of the space of geodesics of a covering manifold to that of the base space. We obtain sufficient conditions for a space to be geodesically connect

Thoralf Hanisch, Burkhard Kleine, Afra Ritzl, Erwin Mueller-Hartmann

In order to analyse the lattice dependence of ferromagnetism in the two-dimensional Hubbard model we investigate the instability of the fully polarized ferromagnetic ground state (Nagaoka state) on the triangular, honeycomb and kagome lattices. We mainly focus on the local instability, applying single spin flip variational wave functions which include majori

U. Schollwoeck, Th. Jolicoeur

We have investigated Haldane's conjecture for the S=2 isotropic antiferromagnetic quantum spin chain with nearest-neighbor exchange J. Using a density matrix renormalization group algorithm for chains up to L=350 spins, we find in the thermodynamic limit a finite spin gap of Delta = 0.085(5)J and a finite spin-spin correlation length xi = 49(1) lattice s

Bobby Hesselbo, R. B. Stinchcombe

We propose a new ensemble for Monte Carlo simulations, in which each state is assigned a statistical weight $1/k$, where $k$ is the number of states with smaller or equal energy. This ensemble has robust ergodicity properties and gives significant weight to the ground state, making it effective for hard optimization problems. It can be used to find free ener

Dongzi Liu, S. Das Sarma

Localization properties of quasi-one dimensional quantum wire nanostructures are investigated using the transfer matrix-Lyapunov exponent technique. We calculate the localization length as a function of the effective mean-field mobility assuming the random disorder potential to be arising from dopant-induced short-range $δ$-function or finite-range Gaussian

D. Z. Liu, K. Levin, J. Maly

We study the order parameter symmetry in bi-layer cuprates such as YBaCuO, where interesting $π$ phase shifts have been observed in Josephson junctions. Taking models which represent the measured spin fluctuation spectra of this cuprate, as well as more general models of Coulomb correlation effects, we classify the allowed symmetries and determine their asso

Paola Pietrini, Julian H. Krolik

The hard X-ray spectra of accreting black holes systems are generally well-fit by thermal Comptonization models with temperatures $\sim 100$ keV. We demonstrate why, over many orders of magnitude in heating rate and seed photon supply, hot plasmas radiate primarily by inverse Compton scattering, and find equilibrium temperatures within a factor of a few of 1

Lars Hernquist, Chris Mihos

Mergers between gas--rich disks and less--massive dwarf galaxies are studied using numerical simulation. As the orbit of a satellite decays through dynamical friction, the primary disk develops large-amplitude spirals in response to its tidal forcing. While these features arise in both the stars and the gas in the disk, the non--axisymmetric structures in th

Julian H. Krolik, Gerard A. Kriss

When an AGN is obscured, the warm reflecting gas nearby can be seen by a combination of bremsstrahlung, intrinsic line emission, and reflection of the nuclear continuum, both by electron scattering and by resonance line scattering. Resonance lines, due both to intrinsic emission and scattering, are particularly prominent in the soft X-ray band. When our line

Stephane Charlot

Invited review, Ringberg conference on "Galaxies in the Young Universe" (Sept94)

J. ~C. ~Breckenridge, T. ~G. ~Steele, V. Elias

A method is developed to construct a non-local massless scalar field theory in a flat quantised space-time generated by an operator algebra. Implicit in the operator algebra is a fundamental length scale of the space-time. The fundamental two-point function of free fields is constructed by assuming that the causal Green functions still have support on the li

Gary McCartor, David G. Robertson

Quantization of gauge theories on characteristic surfaces and in the light-cone gauge is discussed. Implementation of the Mandelstam-Leibbrandt prescription for the spurious singularity is shown to require two distinct null planes, with independent degrees of freedom initialized on each. The relation of this theory to the usual light-cone formulation of gaug

A. Borowiec, V. K. Kharchenko

A new notion of an optimum first order calculi was introduced in [Borowiec, Kharchenko and Oziewicz, 1993]. A module of vector fields for a coordinate differential is defined. Some examples of optimal algebras for homogeneous bimodule commutations are presented. Classification theorem for homogeneous calculi with commutative optimal algebras in two variables

S. Penati, D. Zanon

In this paper we consider affine Toda systems defined on the half-plane and study the issue of integrability, i.e. the construction of higher-spin conserved currents in the presence of a boundary perturbation. First at the classical level we formulate the problem within a Lax pair approach which allows to determine the general structure of the boundary pertu

M. Gourdin, Y. Y. Keum, X. Y. Pham

We show that the factorization assumption in colour-suppressed $B$ meson decays is not ruled out by experimental data on $B \ra K(K^*) + J/Ψ(Ψ^{'})$. The problem previously pointed out might be due to an inadequate choice of hadronic form factors. Within the Isgur-Wise SU(2) heavy flavour symmetry framework, we search for possible $q^2$-dependences of fo

K. Melnikov, O. Yakovlev

We make an attempt to discuss in detail the effects originating from the final state interaction in the processes involving production of unstable elementary particles and their subsequent decay. Two complementary scenarios are considered: the single resonance production and the production of two resonances. We argue that part of the corrections due to the f

M. Vossen, F. Forstmann

The structure of an aqueous solution of sodium chloride at a planar electrode is investigated by integral equation techniques. With the central force water model the aqueous electrolyte is modelled as a mixture of sodium and chloride ions and partially charged hydrogen and oxygen atoms interacting via effective spherically symmetric pair potentials. The bulk

C. Ahn, S. Krivonos, A. Sorin

We present the complete structure of the nonlinear $N=2$ super extension of Polyakov-Bershadsky, $W_3^{(2)}$, algebra with the generic central charge, $c$, at the {\it quantum} level. It contains extra two pairs of fermionic currents with integer spins 1 and 2, besides the currents of $N=2$ superconformal and $W_3^{(2)}$ algebras. For $c\rightarrow \infty$ l

K. A. Mader, L. -W. Wang, A. Zunger

We use realistic pseudopotentials and a plane-wave basis to study the electronic structure of non-periodic, three-dimensional, 2000-atom (AlAs)_n/(GaAs)_m (001) superlattices, where the individual layer thicknesses n,m = {1,2,3} are randomly selected. We find that while the band gap of the equivalent (n = m = 2) ordered superlattice is indirect, random fluct

N. Brunner, K. Svozil, M. Baaz

Thought experiments about the physical nature of set theoretical counterexamples to the axiom of choice motivate the investigation of peculiar constructions, e.g. an infinite dimensional Hilbert space with a modular quantum logic. Applying a concept due to BENIOFF, we identify the intrinsically effective Hamiltonians with those observables of quantum theory

Donald E. Knuth

This note derives the characteristic polynomial of a graph that represents nonjump moves in a generalized game of checkers. The number of spanning trees is also determined.

Leonard Susskind

An argument is presented for the inconsistency of black hole remnants which store the information which falls into black holes. Unlike previous arguments it is not concerned with a possible divergence in the rate of pair production. It is argued that the existence of remnants in the thermal atmosphere of Rindler space will drive the renormalized Newton const

Paolo Provero, Stefano Vinti

The one--loop determinant computed around the kink solution in the 3D $ϕ^4$ theory, in cylindrical geometry, allows one to obtain the partition function of the interface separating coexisting phases. The quantum fluctuations of the interface around its equilibrium position are described by a $c=1$ two--dimensional conformal field theory, namely a 2D free mas

N. K. Nielsen, U. J. Quaade

The physical phase space of the relativistic top, as defined by Hanson and Regge, is expressed in terms of canonical coordinates of the Poincaré group manifold. The system is described in the Hamiltonian formalism by the mass shell condition and constraints that reduce the number of spin degrees of freedom. The constraints are second class and are modified i

A. L. Larsen, N. Sanchez

We study the effects of the spatial curvature on the classical and quantum string dynamics. We find the general solution of the circular string motion in static Robertson-Walker spacetimes with closed or open sections. This is given closely and completely in terms of elliptic functions. The physical properties, string length, energy and pressure are computed

A. L. Larsen, N. Sanchez

We find new classes of {\it exact} string solutions in a variety of curved backgrounds. They include stationary and dynamical (open, closed, straight, finitely and infinitely long) strings as well as {\it multi-string} solutions, in terms of elliptic functions. The physical properties, string length, energy and pressure are computed and analyzed. In anti de

T. Ortin

I study the time--symmetric initial--data problem in theories with a massless scalar field (dilaton), free or coupled to a Maxwell field in the stringy way, finding different initial--data sets describing an arbitrary number of black holes with arbitrary masses, charges and asymptotic value of the dilaton. The presence of the scalar field gives rise to a num

H. HEISELBERG

For physically reasonable bulk and surface properties, quark matter has recently been found to coexist with nuclear matter inside neutron stars in a uniform background of electrons. The microstructure of this mixed phase starts out with a few quark matter droplets embedded in the nuclear matter but as the density of droplets increase towards the center of th

Gerhard Ecker

The main elements and methods of chiral perturbation theory, the effective field theory of the Standard Model below the scale of spontaneous chiral symmetry breaking, are summarized. Applications to the interactions of mesons and baryons at low energies are reviewed, with special emphasis on developments of the last three years. Among the topics covered are

Yongseok Oh, Byung-Yoon Park

We investigate the bound states of heavy mesons with finite masses to a classical soliton solution in the Skyrme model. For a given model Lagrangian we solve the equations of motion exactly so that the heavy vector mesons are treated on the same footing as the heavy pseudoscalar mesons. All the energy levels of higher grand spin states as well as the ground

G. Boyd, Sourendu Gupta, F. Karsch, E. Laermann

We have investigated hadron screening masses, the chiral condensate, and the pion decay constant close to the deconfinement phase transition in the confined phase of QCD. The simulations were done in the quenched approximation, on a lattice of size \mbox{$32^{3}\times 8$}. We examined temperatures ranging from $0.75\tc$ up to $0.92\tc$. We see no sign of a t

E. Laermann, C. Legeland, B. Petersson

We compute heavy quark potentials in pure gauge $SU(3)$ at high temperatures in $2+1$ dimensions and confront them with expectations emerging from perturbative calculations.

S. Randjbar-Daemi, J. Strathdee

The overlap approach to chiral gauge theories on arbitrary $D$--dimensional lattices is studied. The doubling problem and its relation to chiral anomalies for $D=2$ and 4 is examined. In each case it is shown that the doublers can be eliminated and the well known perturbative results for chiral anomalies can be recovered. We also consider the multi--flavour

Luc Blanchet, Thibault Damour, Bala R. Iyer, Clifford M. Will

The rate of gravitational-wave energy loss from inspiralling binary systems of compact objects of arbitrary mass is derived through second post-Newtonian (2PN) order $O[(Gm/rc^2)^2]$ beyond the quadrupole approximation. The result has been derived by two independent calculations of the (source) multipole moments. The 2PN terms, and in particular the finite m

M. R. Norman

In this paper, the Slater integrals for a screened Coulomb interaction of the the Yukawa form are calculated and by fitting the Thomas-Fermi wavevector, good agreement is obtained with experiment for the multiplet spectra of $Pr^{3+}$ and $U^{4+}$ ions. Moreover, a predicted multiplet spectrum for the heavy fermion superconductor $UPt_3$ is shown with a calc

Alan T. Dorsey

The linear response of a thin superconducting strip subjected to an applied perpendicular time-dependent magnetic field is treated analytically using the method of matched asymptotic expansions. The calculation of the induced current density is divided into two parts: an ``outer'' problem, in the middle of the strip, which can be solved using conform

S. Dukan, Z. Tesanovic

Low-temperature quantum oscillations of the dHvA amplitude are shown to persist far below the upper critical field of a strongly type-II superconductor, due to the gapless nature of the BCS quasiparticle spectrum in high fields. The dHvA amplitude in the superconducting state is smaller than its normal state countpart by factor ~[max(T,Gamma]/delta]**2, wher

G. Fáth, J. Sólyom

Chubukov's proposal concerning the possibility of a nondimerized quantum nematic phase in the ground-state phase diagram of the bilinear-biquadratic spin-1 chain is studied numerically. Our results do not support the existence of this phase, but they rather indicate a direct transition from the ferromagnetic into the dimerized phase.

Leon Balents, Steven H. Simon

Using the well known boson mapping, we relate the transverse magnetic susceptibility of a system of flux vortices in 1+1 dimensions to an appropriately defined conductivity of a one-dimensional boson system. The tilt response for a system free of disorder is calculated directly, and it is found that a subtle order of limits is required to avoid deceptive res

Bodo Huckestein

The scaling theory of the transitions between plateaus of the Hall conductivity in the integer Quantum Hall effect is reviewed. In the model of two-dimensional noninteracting electrons in strong magnetic fields the transitions are disorder-induced localization-delocalization transitions. While experimental and analytical approaches are surveyed, the main emp

D. Yoshioka, H. Kato

The persistent current in three-dimensional mesoscopic rings is investigated numerically. The model is tight-binding one with random site-energies and interaction between electrons. The self-consistent Hartree-Fock approximation is adopted for the interaction between electrons, and models with up to $6\times 6\times 20$ sites are investigated. It is shown th

Balu Nadiga

A new discrete-velocity model is presented to solve the three-dimensional Euler equations. The velocities in the model are of an adaptive nature---both the origin of the discrete-velocity space and the magnitudes of the discrete-velocities are dependent on the local flow--- and are used in a finite volume context. The numerical implementation of the model fo

Paul Parsons, John D. Barrow

We investigate the range of inflationary universe models driven by scalar fields possessing a general interaction potential of the form $V(ϕ) = V_0 ϕ^n \exp(-λϕ^m)$. Power-law, de Sitter and intermediate inflationary universes emerge as special cases together with several new varieties of inflation. Analysing the behaviour of these models at the extrema of $

Stacy McGaugh, Jim Schombert, Greg Bothun

We present $UBVI$ and H$α$ images of a sample of Low Surface Brightness (LSB) disk galaxies. These galaxies are generally late types, if they can be sensibly classified at all. However, they are not dwarfs, being intrinsically large and luminous. The morphology of LSB galaxies is discussed in terms of the physical interpretation of the Hubble sequence. Galax

Eduardo Telles, Roberto Terlevich

Recent morphological studies (Telles \& Terlevich 1994) of HII galaxies, i.e. dwarf galaxies dominated by a very luminous starburst, have indicated that luminous HII galaxies tend to show distorted morphology suggestive of tidal interactions triggering the present starburst while low luminosity HII galaxies tend to be instead symmetric and regular. To check

John C Brown, Gregory Beekman, Norman Gray, Alexander L MacKinnon

Possible entropy constraints on particle acceleration spectra are discussed. Solar flare models invoke a variety of initial distributions of the primary energy release over the particles of the flare plasma -- ie., the partition of the energy between thermal and nonthermal components. It is suggested that, while this partition can take any value as far as en

Claude Bertout, Bo Reipurth, Fabien Malbet

We present an overview of what can be done in the field of star formation using the VLT and its advanced instrumentation, and especially with the very high angular resolution provided by the VLT in the VLTI mode. Herbig-Haro objects and early stellar evolution, pre-main sequence binaries, circumstellar disks and surface properties of young stars are investig

Amotz Shemi

Interstellar matter that is accreted onto isolated magnetic neutron stars in the Galaxy ($\sim 10^9$ by number) is accelerated and reflected back by MHD shocks, which envelope the stars. The integrated power in the Galaxy $L_{cr,ns}$ is $ \sgreat 10^{40} {\rm erg \ s^{-1} }$, the energy distribution is a power law of spectral index $> 2$, and the particle en

L. J. Alty, C. J. Fewster

We make a rigorous study of classical field equations on a 2-dimensional signature changing spacetime using the techniques of operator theory. Boundary conditions at the surface of signature change are determined by forming self-adjoint extensions of the Schrödinger Hamiltonian. We show that the initial value problem for the Klein--Gordon equation on this sp

Paul E. Lammert, Daniel S. Rokhsar, John Toner

We consider the weakly first order phase transition between the isotropic and ordered phases of nematics in terms of the behavior of topological line defects. Analytical and Monte Carlo results are presented for a new coarse-grained lattice theory of nematics which incorporates nematic inversion symmetry as a local gauge invariance. The nematic-isotropic tra

Balu Nadiga Galcit

A kinetic flux-splitting procedure used in conjunction with local thermodynamic equilibrium in a finite volume allows us to investigate numerically discrete-velocity gas flows. The procedure, outlined for a general discrete-velocity gas, is used to simulate flows of the nine-velocity gas, a simple two dimensional multiple-speed discrete-velocity gas, wherein

Balu Nadiga, Brad Sturtevant

The exact structure of a shock is computed in a multiple-speed discrete-velocity gas, the nine-velocity gas, wherein the multiplicity of speeds ensures nontrivial thermodynamics. Obtained as a solution of the model Boltzmann equations, the procedure consists of tracking the shock as a trajectory of a three dimensional dynamical system connecting an equilibri

Balu Nadiga, Dale Pullin

We present a simulation scheme for discrete-velocity gases based on {\em local thermodynamic equilibrium}. Exploiting the kinetic nature of discrete-velocity gases, in that context, results in a natural splitting of fluxes, and the resultant scheme strongly resembles the original processes. The kinetic nature of the scheme and the modeling of the {\em infini

Pablo Ares-Gastesi

The Bers-Greenberg theorem tells that the Teichmüller space of a Riemann surface with branch points (orbifold) depends only on the genus and the number of special points, but not on the particular ramification values. On the other hand, the Maskit embedding provides a mapping from the Teichmüller space of an orbifold, into the product of one dimensional Teic

A. M. Jayannavar, P. Singha Deo, T. P. Pareek

We show that several novel effects related to persistent currents can arise in open systems, which have no analogue in closed or isolated systems. We have considered a system of a metallic ring coupled to two electron reservoirs. We show that in the presence of a transport current, persistent currents can flow in a ring even in the absence of magnetic field.

A. M. Jayannavar, P. Singha Deo

We have considered a system of a metallic ring coupled to two electron reservoirs. We show that in the presence of a transport current, the persistent current can flow in a ring, even in the absence of magnetic field. This is purely a quantum effect and is related to the current magnification in the loop. These persistent currents can be observed if one tune

Walter Kob, Hans C. Andersen

We report the results of a large scale computer simulation of a binary supercooled Lennard-Jones liquid. We find that at low temperatures the curves for the mean squared displacement of a tagged particle for different temperatures fall onto a master curve when they are plotted versus rescaled time $tD(T)$, where $D(T)$ is the diffusion constant. The time ran

John Toner, Paul E. Lammert, Daniel S. Rokhsar

This paper is the second in a pair treating a new lattice model for nematic media. In addition to the familiar isotropic (I) and nematically ordered (N) phases, the phase diagram established in the previous paper (Paper I) contains a new, topologically ordered phase (T) occuring at large suppression of topological defects and weak nematic interactions. This

Asher Yahalom

I find conditions under which the "Weak Energy Principle" of Katz, Inagaki and Yahalom (1993) gives necessary and sufficient conditions. My conclusion is that, necessary and sufficient conditions of stability are obtained when we have only two mode coupling in the gyroscopic terms of the perturbed Lagrangian. To illustrate the power of this new energ

Arnon Dar, Nir J. Shaviv

We show that cosmic rays in external galaxies, groups and clusters rich in gas, with an average flux similar to that observed in the Milky Way, could have produced the observed extragalactic diffuse gamma radiation.

R. W. Fairbridge, G. Windelius, H. J. Haubold

The Sun is forced into an orbit around the barycenter of the solar system because of the changing mass distribution of the planets. Solar-planetary-lunar dynamic relationships may form a new basis for understanding and predicting cyclic solar forcing functions on the Earth's climate.

Klaus WERNER, Joerg AICHELIN

To analyse ultrarelativistic nuclear interactions, usually either dynamical models like the string model are employed, or a thermal treatment based on hadrons or quarks is applied. String models encounter problems due to high string densities, thermal approaches are too simplistic considering only average distributions, ignoring fluctuations. We propose a co

Michael Crescimanno, Howard J. Schnitzer

We show that the large N partition functions and Wilson loop observables of two-dimensional Yang-Mills theories admit a universal functional form irrespective of the gauge group. We demonstrate that U(N) QCD_2 undergoes a large N, third-order phase transition on the projective plane at an area-coupling product of π^2/2. We use this as a lemma to provide a di

Zenrō HIOKI

The standard electroweak theory is tested at non-trivial quantum correction level through $α$, $G_F$ and the latest data of the weak-boson masses. The improved-Born approximation and the non-decoupling top-quark effects are studied without depending on the CDF data of $m_t$, while the bosonic effects are examined by fully taking account of it.

R. C. Brower, K. Orginos, C-I Tan

The chiral extension of Quantum Chromodynamics (XQCD) adds to the standard lattice action explicit pseudoscalar meson fields for the chiral condensates. With this action, it is feasible to do simulations at the chiral limit with zero mass Goldstone modes. We review the arguments for why this is expected to be in the same universality class as the traditional

M. A. Halasz, J. J. M. Verbaarschot

Recently, Kalkreuter obtained the complete Dirac spectrum for an $SU(2)$ lattice gauge theory with dynamical staggered fermions on a $12^4$ lattice for $β=1.8$ and $β=2.8$. We performed a statistical analysis of his data and found that the eigenvalue correlations can be described by the Gaussian Symplectic Ensemble. In particular, long range fluctuations are

M. Fukugita, Y. Kuramashi, H. Mino, M. Okawa

Lattice QCD calculation of s-wave hadron scattering lengths in the channels π-π, π-N, K-N, {\bar K}-N and N-N is carried out in the quenched QCD at $β=6/g^2=5.7$. A variant of the method of wall sourceis developed for this purpose, which reduces the computer time by a factor L^3 on an L^3xT lattice compared to the conventional point source method and avoids

Patrick R Brady, Chris M Chambers

Using the general solution to the Einstein equations on intersecting null surfaces developed by Hayward, we investigate the non-linear instability of the Cauchy horizon inside a realistic black hole. Making a minimal assumption about the free gravitational data allows us to solve the field equations along a null surface crossing the Cauchy Horizon. As in the

Salvatore Mignemi, Hans - Jürgen Schmidt

We consider the lagrangian $L=F(R)$ in classical (=non-quantized) two-dimensional fourth-order gravity and give new relations to Einstein's theory with a non-minimally coupled scalar field. We distinguish between scale-invariant lagrangians and scale-invariant field equations. $L$ is scale-invariant for $F = c_1 R\sp {k+1}$ and a divergence for $F=c_2 R$

J. Siewert, Gerd Schön, Andrei D. Zaikin

Single electron tunneling into small superconducting islands is sensitive to the gap energy of the excitations created in the process and, hence, depends on the parity of the electron number in the island. We study these effects by analyzing the kinetics of the system. Since the interplay of Coulomb blockade and parity effects leads to a blocking of single e

Giovanni Gallavotti

The volume contraction obeys a large deviation rule.

Ian Hinchliffe, Lawrence Berkeley Lab

Invited talk presented at the 1994 Meeting of The Division of Particles and Fields of the American Physical Society, Albuquerque NM, August 1-6, 1994

Dieter R. Brill

Exact solutions of the Einstein-Maxwell equations that describe moving black holes in a cosmological setting are discussed with the aim of discovering the global structure and testing cosmic censorship. Continuation beyond the horizons present in these solutions is necessary in order to identify the global structure. Therefore the possibilities and methods o

L. Alvarez-Ruso, M. J. Vicente-Vacas

In this letter we study the high energy behavior of the forward differential cross section for the $^{18}O(π^+,π^-)^{18}Ne$ double charge exchange reaction. We have evaluated the sequential and the meson exchange current mechanisms. The meson exchange current contribution shows a very weak energy dependence and becomes relevant at incident pion kinetic energ

C. Stampfl, M. Scheffler

Results of recent density functional theory calculations for alkali metal adsorbates on close-packed metal surfaces are discussed. Single adatoms on the (111) surface of Al and Cu are studied with the self-consistent surface Green-function method by which the pure adsorbate-substrate interaction may be analyzed. Higher coverage ordered adlayers of K on Al(11

Sumit R. Das

We consider the geometric entropy of free nonrelativistic fermions in two dimensions and show that it is ultraviolet finite for finite fermi energies, but divergent in the infrared. In terms of the corresponding collective field theory this is a {\em nonperturbative} effect and is related to the soft behaviour of the usual thermodynamic entropy at high tempe

Michael Lassig

The Kardar-Parisi-Zhang (KPZ) equation of nonlinear stochastic growth in d dimensions is studied using the mapping onto a system of directed polymers in a quenched random medium. The polymer problem is renormalized exactly in a minimally subtracted perturbation expansion about d = 2. For the KPZ roughening transition in dimensions d > 2, this renormalization

Rikard Bögvad

Reason for withdrawal: There is a serious mistake in the calculation of the divisor of the rational section used in the proof of Prop. 2.2.1., and with the correct value the argument does not work.

Rikard Bögvad

Using reduction to positive characteristic and the method of Frobenius splitting of diagonals, due to Mehta and Ramanathan, it is shown that homogeneous coordinate rings for either proper and smooth toric varieties or Schubert varieties are Koszul algebras.

R S MacKay, J A Sepulchre

We study the stationary states of networks consisting of weakly coupled bistable units. We prove the existence of a high multiplicity of stable steady states in networks with very general inter-unit dynamics. We present a method for estimating the critical coupling strength below which these stationary states persist in the network. In some cases, the presen

S. Ayik, Ph. Chomaz, M. Colonna, J. Randrup

The Boltzmann-Langevin dynamics of harmonic modes in nuclear matter is analyzed within linear-response theory, both with an elementary treatment and by using the frequency-dependent response function. It is shown how the source terms agitating the modes can be obtained from the basic BL correlation kernel by a simple projection onto the associated dual basis

C. Hanhart, S. Krewald

A relativistic Faddeev model for the baryon octet is extended to treat the baryon decuplet. We find that after determining the model parameters in the mesonic sector the masses of both nucleon and delta deviate by less than 5\% from the experimental data and show only a very weak dependence on the constituent quark mass.

Oleg Pankratov, Matthias Scheffler

Electron-hole excitations in the surface bands of GaAs(110) are analyzed using constrained density-functional theory calculations. The results show that Frenkel-type autolocalized excitons are formed. The excitons induce a local surface unrelaxation which results in a strong exciton-exciton attraction and makes complexes of two or three electron-hole pairs m