May 1996 arXiv papers — page 7

Robert Paternoga, Robert Graham

Quantum states of the diagonal Bianchi type IX model with negative cosmological constant $Λ$ are obtained by transforming the Chern-Simons solution in Ashtekar's variables to the metric representation. We apply our method developed earlier for $Λ>0$ and obtain five linearly independent solutions by using the complete set of topologically inequivalent int

P. V. Moniz

The question if conserved currents can be sensibly defined in supersymmetric minisuperspaces is investigated in this essay. The objective is to employ exclusively the differential equations obtained {\em directly} from the Lorentz and supersymmetry quantum constraints. The ``square-root'' structure of N=1 supergravity is the motivation to contemplate

Pankaj S. Joshi, Andrzej Krolak

We investigate the occurrence and nature of naked singularities in the Szekeres space-times. These space-times represent irrotational dust. They do not have any Killing vectors and they are generalisations of the Tolman-Bondi-Lemaitre space-times. It is shown that in these space-times there exist naked singularities that satisfy both the limiting focusing co

Muyu Guo, R. N. Bhatt, David A. Huse

We report a Monte Carlo study of the effects of {\it fluctuations} in the bond distribution of Ising spin glasses in a transverse magnetic field, in the {\it paramagnetic phase} in the $T\to 0$ limit. Rare, strong fluctuations give rise to Griffiths singularities, which can dominate the zero-temperature behavior of these quantum systems, as originally demons

D. Stauffer, P. M. C. de Oliveira, S. M. Moss de Oliveira, R. M. Zorzenon dos Santos

Modifying the Redfield model of sexual reproduction and the Penna model of biological aging, we compare reproduction with and without recombination in age-structured populations. In contrast to Redfield and in agreement with Bernardes we find sexual reproduction to be preferred to asexual one. In particular, the presence of old but still reproducing males he

J. K. Freericks, Mark Jarrell, G. D. Mahan

The anharmonic electron-phonon problem is solved in the infinite-dimensional limit using quantum Monte Carlo simulation. Charge-density-wave order is seen to remain at half filling even though the anharmonicity removes the particle-hole symmetry (and hence the nesting instability) of the model. Superconductivity is strongly favored away from half filling (re

Wolfhard Janke, Tilman Sauer

We present a comparison of the performance of two non-local update algorithms for path integral Monte Carlo (PIMC) simulations, the multigrid Monte Carlo method and the staging algorithm. Looking at autocorrelation times for the internal energy we show that both refined algorithms beat the slowing down which is encountered for standard local update schemes i

C. Winkelholz, Rosario Fazio, F. W. J. Hekking, Gerd Schön

We study the frequency and space dependence of the local tunneling density of states of a Luttinger liquid (LL) which is connected to a superconductor. This coupling {\em strongly} modifies the single-particle properties of the LL. It significantly enhances the density of states near the Fermi level, whereas this quantity vanishes as a power law for an isola

D. Poilblanc, H. Endres, F. Mila, M. G. Zacher

Interchain hopping in systems of coupled chains of correlated electrons is investigated by exact diagonalizations and Quantum-Monte-Carlo methods. For two weakly coupled Hubbard chains at commensurate densities (e.g. n=1/3) the splitting at the Fermi level between bonding and antibonding bands is strongly reduced (but not suppressed) by repulsive interaction

Dennis P. Clougherty

The stability of Ne@C$_{60}$ and He@C$_{60}$ is discussed in the context of a spherical model where the carbon atoms are smeared out into a uniform shell. The electronic properties of the sixty $π$ electrons together with those of the central atom are treated in the Thomas-Fermi approximation. Simple electrostatic reasoning elucidates the nature of the radia

Daniel E. Vanden Berk, Jean M. Quashnock, Donald G. York, Brian Yanny

We have compiled a new and extensive catalog of heavy-element QSO absorption line systems and analyzed the distribution of absorbers in bright and faint QSOs, to search for gravitational lensing of background QSOs by the matter associated with the absorbers. There is a highly significant excess of C {\sc iv} absorbers in bright QSOs in the redshift range $z=

A. Vazdekis, E. Casuso, R. F. Peletier, J. E. Beckman

We have developed a new stellar population synthesis model designed to study early-type galaxies. It provides optical and near-infrared colors, and line indices for 25 absorption lines. It can synthesize single age, single metallicity stellar populations or follow the galaxy through its evolution from an initial gas cloud to the present time. The model incor

R. E. Griffiths, S. Casertano, M. Im, K. U. Ratnatunga

Using data from the HST Medium Deep Survey, a long-term Key Project, together with generically similar archived data, we have discovered evidence for weak gravitational `shear' of background field galaxies (I = 22 -- 26) in the vicinity of isolated, foreground galaxies ( I = 15 -- 22), especially those of early type. The statistical lensing is demonstrat

Karl Mannheim, Dieter Hartmann, Burkhardt Funk

Some gamma-ray burst (GRB) spectra exhibit high energy tails with the highest photon energy detected at 18 GeV. The spectral slope of the high-energy tails is sufficiently flat in nu F_nu to consider the possibility of their detection at still higher energies. We calculate how many bursts can reasonably be expected above a given energy threshold for a cosmol

K. Mannheim, S. Westerhoff, H. Meyer, H. -H. Fink

Blazars with redshifts z<0.1 are likely candidates for detection at energies in the range 300 GeV - 50 TeV with Cerenkov telescopes and scintillator arrays. We present gamma-ray flux predictions for a sample of 15 nearby flat-spectrum radio sources fitting the proton blazar model of Mannheim (1993a) to their observed broad-band spectral energy distributions.

Andrew Gould

Je presente une revue des microlentilles gravitationnelles en quatre lecons. Dans un premier temps, je discute la theorie des microlentilles dans le contexte general des lentilles, en incluant les effets de la taille finie des sources, de la parallaxe, et du retard temporel entre les images. Dans la deuxieme lecon, j&#39;analyse les experiences courantes. Je

Misao Sasaki, Takahiro Tanaka

We investigate the quantum fluctuations of an inflaton field in a two-field model of one-bubble open inflation. One of the inflatons is assumed to be responsible for the first false vacuum stage of inflation and the other is assumed to be responsible for the second slow-roll stage of inflation. The mass of the second inflaton is assumed to be negligible thro

Kazuhiro Yamammoto, Misao Sasaki, Takahiro Tanaka

We first develop a method to calculate a complete set of mode functions which describe the quantum fluctuations generated in one-bubble open inflation models. We consider two classes of models. One is a single scalar field model proposed by Bucher, Goldhaber and Turok and by us as an example of the open inflation scinario, and the other is a two-field model

Antoinette Songaila, Lennox L. Cowie

The recent discovery of carbon in close to half of the low neutral hydrogen column density [$N({\rm H~I}) > 3\ten{14}\cm2$] Lyman forest clouds toward $z \sim 3$ quasars has challenged the widely held view of this forest as a chemically pristine population uniformly distributed in the intergalactic medium, but has not eliminated the possibility that a primor

Eric L. Sandquist, Michael Bolte, Peter B. Stetson

We present new BVI photometry for the halo globular cluster M5, and examine the B- and I-band luminosity functions (LFs), based on over 20,000 stars. We do not see evidence in the LF of a ``subgiant excess&#39;&#39; or of a discrepancy in the relative numbers of stars on the red-giant branch and main sequence, both of which have been claimed in more metal-po

K. Heinemann, G. H. Hoffstatter

Polarized protons have never been accelerated to more than about $25$GeV. To achieve polarized proton beams in RHIC (250GeV), HERA (820GeV), and the TEVATRON (900GeV), ideas and techniques new to accelerator physics are needed. In this publication we will stress an important aspect of very high energy polarized proton beams, namely the fact that the equilibr

Hoi-Kwong Lo, H. F. Chau

There had been well known claims of ``provably unbreakable&#39;&#39; quantum protocols for bit commitment and coin tossing. However, we, and independently Mayers, showed that all proposed quantum bit commitment (and therefore coin tossing) schemes are, in principle, insecure because the sender, Alice, can always cheat successfully by using an EPR-type of att

A. Giveon, M. Porrati

Duality groups of Abelian gauge theories on four manifolds and their reduction to two dimensions are considered. The duality groups include elements that relate different space-times in addition to relating different gauge-coupling matrices. We interpret (some of) such dualities as the geometrical symmetries of compactified theories in higher dimensions. In

John M. Cornwall

There is still confusion about the correct form of the area law for the baryonic Wilson loop (BWL) of QCD. Strong-coupling (i.e., finite lattice spacing in lattice gauge theory) approximations suggest the form $\exp [-KA_Y]$, where $K$ is the $q\bar{q}$ string tension and $A_Y$ is the global minimum area, generically a three-bladed area with the blades joine

Silvano Simula

The production of slow nucleons in semi-inclusive deep inelastic electron scattering off the deuteron is investigated in the region $x \gsim 0.3$. It is shown that within the spectator mechanism the semi-inclusive cross section exhibits a scaling property even at moderate values of $Q^2$ ($\sim$ few $(GeV/c)^2$) accessible at present facilities, like $CEBAF$

Rolf Walder, Doris Folini

Radiative shock waves show a strong cooling instability at temperatures above approximately 2 times 10^5 K. We numerically investigate this instability by simulating different astronomical objects in which colliding flows play an outstanding role: Wind bubbles, supernova remnants, and colliding winds. Computing the flow of each object over a large part of it

Gregory C. Psaltakis

We study the Drude weight D and the total optical weight K for a t-t&#39;-J model on a square lattice that exhibits a metallic phase-modulated antiferromagnetic ground state close to half-filling. Within a suitable 1/N expansion that includes leading quantum-fluctuation effects, D and K are found to increase linearly with small hole doping away from the Mott

Neil J. Cornish, Janna J. Levin

For the past decade there has been a considerable debate about the existence of chaos in the mixmaster cosmological model. The debate has been hampered by the coordinate, or observer dependence of standard chaotic indicators such as Lyapanov exponents. Here we use coordinate independent, fractal methods to show the mixmaster universe is indeed chaotic.

H. Kleinert, A. Pelster

We present a simpler and more powerful version of the recently-discovered action principle for the motion of a spinless point particle in spacetimes with curvature and torsion. The surprising feature of the new principle is that an action involving only the metric can produce an equation of motion with a torsion force, thus changing geodesics to autoparallel

C. J. Burden, D. -S. Liu

A formalism for studying heavy quarks in terms of model Dyson-Schwinger equations is developed. The formalism is the natural extension of a technique which has proved successful in a number of studies of light hadron physics. The dressed heavy quark propagator, calculated to leading order in the inverse quark mass, is incorporated in a treatment of mesons co

Yu. Song-Ju, T. Fukuyama

We argue the integrability of the generalized KdV(GKdV) equation using the Painlevé test. For $d( \le 2)$ dimensional space, GKdV equation passes the Painlevé test but does not for $d \geq 3$ dimensional space. We also apply the Ablowitz-Ramani-Segur&#39;s conjecture to the GKdV equation in order to complement the Painlevé test.

H. F. Chau, H. -K. Lo

We show that the entropy of entanglement of a state characterizes its ability to teleport. In particular, in order to teleport faithfully an unknown quantum $N$-state, the two users must share an entangled state with at least $\log_2 N$ bits entropy of entanglement. We also note that the maximum capacity for a mixed state ${\cal M}$ to teleport equals the ma

Asher Peres

If scattering amplitudes are ordinary complex numbers (not quaternions) there is a universal algebraic relationship between the six coherent cross sections of any three scatterers (taken singly and pairwise). A violation of this relationship would indicate either that scattering amplitudes are quaternions, or that the superposition principle fails. Some poss

Joseph I. Kapusta, Axel P. Vischer

We study the dynamical formation of disoriented chiral condensates in very high energy nucleus-nucleus collisions using Bjorken hydrodynamics and relativistic nucleation theory. It is the dynamics of the first order confinement phase transition which controls the evolution of the system. Every bubble or fluctuation of the new, hadronic, phase obtains its own

K. Yoshida, A. Hosaka, M. Oka

We study effects of nonlocality in the nuclear force on the G-matrix elements for finite nuclei. Nuclear G-matrix elements for $\O16$ are calculated in the harmonic oscillator basis from a nonlocal potential which models quark exchange effects between two nucleons. We employ a simple form of potential that gives the same phase shifts as a realistic local nuc

Keith A. Kearnes, Ågnes Szendrei

We describe a sufficient condition for the localization functor to be a categorical equivalence. Using this result we explain how to simplify the test for projectivity. This leads to a description of the strictly simple algebras which are projective in the variety they generate. A byproduct of our efforts is the result that if A and B are strictly simple and

L. Palacios

We are presenting a general solution to the classical Einstein--Maxwell--dilaton--axion equations starting from a metric of type--D. Namely, this stringy solution is the result of a transformation on a general vacuum type--D solution to the Einstein&#39;s equations which was studied in detail some years ago.

P. A. Marchetti, Zhao-Bin Su, Lu Yu

We perform a dimensional reduction of the $U(1)\times SU(2)$ Chern--Simons bosonization and apply it to the $t-J$ model, relevant for high $T_c$ superconductors. This procedure yields a decomposition of the electron field into a product of two ``semionic&#34; fields, i.e. fields obeying abelian braid statistics with statistics parameter $θ={1\over 4}$, one c

E. Halyo, A. Rajaraman, L. Susskind

It is known that the naive version of D-brane theory is inadequate to explain the black hole entropy in the limit in which the Schwarzschild radius becomes larger than all compactification radii. We present evidence that a more consistent description can be given in terms of strings with rescaled tensions. We show that the rescaling can be interpreted as a r

Csaba Csaki, Lisa Randall, Witold Skiba

In this paper we introduce a new class of theories which dynamically break supersymmetry based on the gauge group SU(n)xSU(3)xU(1) for even n. These theories are interesting in that no dynamical superpotential is generated in the absence of perturbations. For the example SU(4)xSU(3)xU(1) we explicitly demonstrate that all flat directions can be lifted throug

R Delbourgo, A Kalloniatis, G Thompson

Renormalization factors are most easily extracted by going to the massless limit of the quantum field theory and retaining only a single momentum scale. We derive factors and renormalized Green functions to all orders in perturbation theory for rainbow graphs and vertex (or scattering diagrams) at zero momentum transfer, in the context of dimensional renorma

L. Silvestrini

We analyze constraints on low-energy flavour-changing sfermion mass terms, coming from FCNC and CP violating processes, in the model-independent framework of the mass insertion method. We discuss the relevance of these constraints as tests of supersymmetric extensions of the standard model; in particular, we consider grand-unified models and models with non-

Mark Hindmarsh

A relativistic generalisation of a well-known method for approximating the dynamics of topological defects in condensed matter is constructed, and applied to the evolution of domain walls in a cosmological context. It is shown that there are self-similar ``scaling&#39;&#39; solutions, for which one can in principle calculate many quantities of interest witho

P V Landshoff

The BFKL pomeron is swamped by the soft pomeron, at least at t=0.

M. Stratmann, W. Vogelsang

We study photoproduction of jets and heavy flavors in a polarized collider mode of HERA and in polarized $ep$ collisions at $\sqrt{S}\approx 30$ GeV. We examine the sensitivity of the cross sections and their asymmetries to the proton&#39;s polarized gluon distribution and to the completely unknown parton distributions of longitudinally polarized photons.

Subir Mohan

We show that the baryon asymmetry produced by the out of equilibrium decay of heavy $GUT$ scalars can be the baryon asymmetry that is observed today. No restrictions need be imposed on the initial values of $B$, $L$ and $B-L$, nor on the neutrino masses; no new symmetries need be gauged nor new fermions introduced. We find two mechanisms that can bring this

Rajiv V. Gavai, Raju Venugopalan

Using weak coupling methods McLerran and Venugopalan~\cite{LV1} expressed the parton distributions in large nuclei as correlation functions of a two dimensional Euclidean field theory. The theory has the dimensionful coupling $g^2 μ$, where $μ^2\sim A^{1/3}$ is the valence quark color charge squared per unit area. We use a lattice regularization to investiga

J. F. Gunion, B. Grzadkowski, X. -G. He

The optimal procedure for extracting the coefficients of different components of a cross section which takes the form of unknown coefficients times functions of known kinematical form is developed. When applied to $\epem\to t\anti t+$Higgs production at $\rts=1\tev$ and integrated luminosity of $200\fbi$, we find that the $t\anti t\to$Higgs CP-even and CP-od

Seyong Kim, Yoonbai Kim

Three dimensional Thirring model with $N$ four-component Dirac fermions, reformulated as a lattice gauge theory, is studied by computer simulation. According to an $8^{3}$ data and preliminary $16^3$ data, chiral symmetry is found to be spontaneously broken for $N=2,\;4$ and 6. $N=2$ data exhibits long tail of the non-vanishing chiral condensate into weak co

P. Bialas, Z. Burda

We study grand--canonical and canonical properties of the model of branched polymers proposed in \cite{adfo}. We show that the model has a fourth order phase transition and calculate critical exponents. At the transition the exponent $γ$ of the grand-canonical ensemble, analogous to the string susceptibility exponent of surface models, $γ\sim 0.3237525...$ i

H. C. Rosu

A comparison between the proposals made to measure Hawking-like effects and the Unruh effect in the laboratory is given at the level of their estimates. No satisfactory scheme exists as yet for their detection.

Carmen Chicone, Bahram Mashhoon, David Retzloff

The gravitational ionization of a Keplerian binary system via normally incident periodic gravitational radiation of definite helicity is discussed. The periodic orbits of the planar tidal equation are investigated on the basis of degenerate continuation theory. The relevance of the Kolmogorov-Arnold-Moser theory to the question of gravitational ionization is

G. E. Matsas, D. Sudarsky, A. Higuchi

We show that in complete analogy with the usual bremsstrahlung process, when studied from the coaccelerated observer&#39;s point of view, a charge moving along the integral curves of the static Killing field in the exterior of a static black hole gives rise to the emission of zero-energy photons, induced by the thermal bath of Hawking Radiation.

T. Stavracou

The geometry of graded principal bundles is discussed in the framework of graded manifold theory of Kostant-Berezin-Leites. In particular, we prove that a graded principal bundle is globally trivial if and only if it admits a global graded section and, further, that the sheaf of vertical derivations on such a bundle coincides with the graded distribution ind

Tom Kennedy

We consider the majority rule renormalization group transformation applied to nearest neighbor Ising models. For the square lattice with 2 by 2 blocks we prove that if the temperature is sufficiently low, then the transformation is not defined. We use the methods of van Enter, Fernandez and Sokal, who proved the renormalized measure is not Gibbsian for 7 by

J. Machta, Y. S. Choi, A. Lucke, T. Schweizer

The invaded cluster algorithm, a new method for simulating phase transitions, is described in detail. Theoretical, albeit nonrigorous, justification of the method is presented and the algorithm is applied to Potts models in two and three dimensions. The algorithm is shown to be useful for both first-order and continuous transitions and evidently provides an

Royce Kam, Herbert Levine

Domains of condensed-phase monolayers of chiral molecules exhibit a variety of interesting nonequilibrium structures when formed via pressurization. To model these domain patterns, we add a complex field describing the tilt degree of freedom to an (anisotropic) complex-phase-field solidification model. The resulting formalism allows for the inclusion of (in

Jaroslav Fabian, Philip B. Allen

Anharmonic decay rates are calculated for a realistic atomic model of amorphous silicon. The results show that the vibrational states decay on picosecond timescales and follow the two-mode density of states, similar to crystalline silicon, but somewhat faster. Surprisingly little change occurs for localized states. These results disagree with a recent experi

H. Haugerud, T. Haugset, F. Ravndal

Using the Euler-Maclaurin summation we calculate analytically the internal energy for non-interacting bosons confined within a harmonic oscillator potential. The specific heat shows a sharp $λ$-like peak indicating a condensation into the ground state at a well-defined transition temperature. Full agreement is obtained with direct numerical calculation of th

Udo Hahn, Michael Strube

In this paper, we present a model of anaphor resolution within the framework of the centering model. The consideration of an incremental processing mode introduces the need to manage structural ambiguity at the center level. Hence, the centering framework is further refined to account for local and global parsing ambiguities which propagate up to the level o

Naoki Abe, Hang Li

We consider the problem of learning co-occurrence information between two word categories, or more in general between two discrete random variables taking values in a hierarchically classified domain. In particular, we consider the problem of learning the `association norm&#39; defined by A(x,y)=p(x, y)/(p(x)*p(y)), where p(x, y) is the joint distribution fo

Marc Kamionkowski, Nicolaos Toumbas

It is quite remarkable that seventy years after Hubble discovered the expansion of the Universe, we still have no idea in which of the three Friedmann-Robertson-Walker geometries we live. Most of the current literature has focussed on flat or open models. Here, we construct a viable model of the Universe which has closed geometry even though the nonrelativis

Brian Chaboyer

Globular clusters are the oldest objects in the Galaxy whose age may be accurately determined. As such globular cluster ages provide the best estimate for the age of the universe. The age of a globular cluster is determined by a comparison between theoretical stellar evolution models and observational data. Current uncertainties in the stellar models and age

Geza Kovacs, Johanna Jurcsik

We use a large sample of RRab stars in globular clusters and in the Sculptor dwarf galaxy to decipher the relation between the Fourier decomposition and the luminosity. For fixing the zero point of the relation, we use the latest Baade-Wesselink (BW) results. It is shown that the most plausible representation of the absolute brightness (in V color) consists

Dong Lai

Recent timing observations of PSR J0045-7319 reveal that the neutron star/B star binary orbit is decaying on a time scale of $|\Porb/\dot\Porb|=0.5$ Myr, shorter than the characteristic age ($τ_c=3$ Myr) of the pulsar (Kaspi et al.~1996a). We study mechanisms for the orbital decay. The standard weak friction theory based on static tide requires far too short

Dong Lai

What happens to a neutron star or white dwarf near its maximum mass limit when it is brought into a close binary orbit with a companion? Such situation may occur in the progenitors of Type Ia supernovae and in coalescing neutron star binaries. Using an energy variational principle, we show that tidal field reduces the central density of the compact object, m

Erich Poppitz, Yael Shadmi, Sandip P. Trivedi

We study the non-perturbative behavior of some N=1 supersymmetric product-group gauge theories with the help of duality. As a test case we investigate an SU(2)xSU(2) theory in detail. Various dual theories are constructed using known simple-group duality for one group or both groups in succession. Several stringent tests show that the low-energy behavior of

Juan Garcia-Bellido, Andrei Linde, David Wands

We investigate the recently proposed hybrid inflation models with two stages of inflation. We show that quantum fluctuations at the time corresponding to the phase transition between the two inflationary stages can trigger the formation of a large number of inflating topological defects. In order to study density perturbations in these models we develop a ne

Jose M Figueroa-O&#39;Farrill, Sonia Stanciu

In hep-th/9506151 we started a programme devoted to the systematic study of the conformal field theories derived from WZW models based on nonreductive Lie groups. In this, the second part, we continue this programme with a look at the N=1 and N=2 superconformal field theories which arise from both gauged and ungauged supersymmetric WZW models. We extend the

Stefano Catani, Michael H. Seymour

We present a new general algorithm for calculating arbitrary jet cross sections in arbitrary scattering processes to next-to-leading accuracy in perturbative QCD. The algorithm is based on the subtraction method. The key ingredients are new factorization formulae, called dipole formulae, which implement in a Lorentz covariant way both the usual soft and coll

A. Karlhede, S. A. Kivelson, K. Lejnell, S. L. Sondhi

We have investigated the formation of spin textures at the edges of quantum Hall systems for several ferromagnetic filling factors. The textures are driven by the same physics that leads to ``skyrmions&#39;&#39; in the bulk. For hard confinement and large Zeeman energies, the edges are narrow and spin polarized. Away from this limit and for $ν=1/3$, $1/5$ an

Thomas Guhr, Tilo Wettig

We compute an analogue of the Itzykson-Zuber integral for the case of arbitrary complex matrices. The calculation is done for both ordinary and supermatrices by transferring the Itzykson-Zuber diffusion equation method to the space of arbitrary complex matrices. The integral is of interest for applications in Quantum Chromodynamics and the theory of two-dime

L. Covi, E. Roulet, F. Vissani

We compute the CP violation in the decays of heavy electroweak singlet neutrinos, arising from both the one--loop vertex corrections and the wave function mixing. We extend the computation to the supersymmetric version of the model and discuss the implications for the generation of a lepton number asymmetry by the out of equilibrium decay of the heavy (s)neu

Peter Neu, Jochen Rau

Using the Robertson projection operator formalism, we derive generalized Bloch equations which describe the dynamics of a biased two-level tunneling system strongly driven by an external field and weakly coupled to a super-Ohmic heat bath. The generalized Bloch equations constitute a set of coupled nonlinear integro-differential equations. With their help we

C. Fuchs, T. Gaitanos, H. H. Wolter

We study the influence of non-equilibrium phase space effects on the dynamics of heavy ion reactions within the relativistic BUU approach. We use realistic Dirac-Brueckner-Hartree-Fock (DBHF) mean fields determined for two-Fermi-ellipsoid configurations, i.e. for colliding nuclear matter, in a local phase space configuration approximation (LCA). We compare t

H. G. Kausch, G. Takacs, G. M. T. Watts

We consider the RSOS S-matrices of the Phi(1,5) perturbed minimal models which have recently been found in the companion paper [hep-th/9604098]. These S-matrices have some interesting properties, in particular, unitarity may be broken in a stronger sense than seen before, while one of the three classes of Phi(1,5) perturbations (to be described) shares the s

Manfred Requardt

Starting from the hypothesis that both physics, in particular space-time and the physical vacuum, and the corresponding mathematics are discrete on the Planck scale we develop a certain framework in form of a class of &#39; cellular networks&#39; consisting of cells (nodes) interacting with each other via bonds according to a certain &#39;local law&#39; whic

R. S. Warwick et al

A series of {\sl ROSAT\/}, {\sl ASCA\/} and Compton Gamma-Ray Observatory ({\sl CGRO\/}) observations of the Seyfert galaxy NGC 4151 were carried out during the period 1993 November 30 to December 13 as part of an intensive campaign to study the multiwavelength spectral characteristics of its short time-scale variability. In the softest X-ray bands monitored

Roland Svensson

X-ray and gamma-ray observations of Seyfert 1 galaxies are briefly reviewed. Both thermal and non-thermal model for X-ray and gamma-ray emission are discussed. Particular attention is given to various disc-corona models including both homogeneous and inhomogeneous (patchy) corona models. Recent work on exact radiative transfer in such geometries are reviewed

B. R. Iyer, K. D. Kokkotas

In this article we summarise the proceedings of the Workshop on Gravitational Waves held during ICGC-95. In the first part we present the discussions on 3PN calculations (L. Blanchet, P. Jaranowski), black hole perturbation theory (M. Sasaki, J. Pullin), numerical relativity (E. Seidel), data analysis (B.S. Sathyaprakash), detection of gravitational waves fr

Jan de Boer, Laszlo Feher

It is known from a work of Feigin and Frenkel that a Wakimoto type, generalized free field realization of the current algebra $\widehat{\cal G}_k$ can be associated with each parabolic subalgebra ${\cal P}=({\cal G}_0+{\cal G}_+)$ of the Lie algebra ${\cal G}$, where in the standard case ${\cal G}_0$ is the Cartan and ${\cal P}$ is the Borel subalgebra. In t

Yi Liao, Xiaoyuan Li

The rare decay $H\to γγ$ is a promising detection channel for an intermediate mass Higgs boson. We compute its two-loop $O(α^2 G_F m_t^2)$ correction in the standard model and find that the relative correction to the decay rate runs between $0.7%$ and $0.5%$ for $M_H=80-150$ GeV. The analogous correction to the amplitude for $gg\to H$ is recovered as a speci

Xiao-Song Lin, Feng Tian, Zhenghan Wang

Using a probabilistic interpretation of the Burau representation of the braid group offered by Vaughan Jones, we generalize the Burau representation to a representation of the semigroup of string links. This representation is determined by a linear system, and is dominated by finite type string link invariants. For positive string links, the representation m

Wen-Xiu Ma

A $2n$-dimensional Lax integrable system is proposed by a set of specific spectral problems. It contains Takasaki equations, the self-dual Yang-Mills equations and its integrable hierarchy as examples. An explicit formulation of Darboux transformations is established for this Lax integrable system. The Vandermonde and generalized Cauchy determinant formulas

David A. Meyer

Unitarity of the global evolution is an extremely stringent condition on finite state models in discrete spacetime. Quantum cellular automata, in particular, are tightly constrained. In previous work we proved a simple No-go Theorem which precludes nontrivial homogeneous evolution for linear quantum cellular automata. Here we carefully define general quantum

Paul Benioff

Quantum computers are important examples of processes whose evolution can be described in terms of iterations of single step operators or their adjoints. Based on this, Hamiltonian evolution of processes with associated step operators $T$ is investigated here. The main limitation of this paper is to processes which evolve quantum ballistically, i.e. motion r

Andrew Steane

Methods of finding good quantum error correcting codes are discussed, and many example codes are presented. The recipe C_2^{\perp} \subseteq C_1, where C_1 and C_2 are classical codes, is used to obtain codes for up to 16 information qubits with correction of small numbers of errors. The results are tabulated. More efficient codes are obtained by allowing C_

Il-Tong Cheon

Considering the stresses due to the vacuum fluctuation and the electric charge loaded over the surface of a spherical cavity, we estimate the maximum value of the charge. Since this value is independent of the cavity size and parameter free, it is regarded as the electric unit charge. Our result is $Q= 1.55\times 10^{-19}$ Coulomb which implies the relevant

Wang Zhen

The concepts of the perfect system and degeneracy are introduced. A special symmetry is found which is related to the entropy invariant. The inversion relation of system is obtained which is used to give the oppsite direction of time to classical sencond law of thermodanymics. The nature of time is discussed together with causality relation. A new understand

Wang Zhen

A pair of symmetric expressions for the second law of thermodynamics is put forward. The conservation and transfer of entropy is discussed and applied to problems like biology, culture and life itself. A new explanation is given to the cosmic expansion with the concept of diversity in this theory. The problem of contingency and necessity is also discussed.

Wang Zhen

The concept of uncertainty quanta for a general system is introduced and applied to some important problems in physics and mathematics. EPR paradox gives new clue to the further understanding of particle correlation which turns out to be the nature of this world. Randomness in quantum mechanics, statistical physics and chaos is integrated. A picture for a ne

Giovanni Felder, Alexander Varchenko

To each representation of the elliptic quantum group $E_{τ,η}(sl_2)$ is associated a family of commuting transfer matrices. We give common eigenvectors by a version of the algebraic Bethe ansatz method. Special cases of this construction give eigenvectors for IRF models, for the eight-vertex model and for the two-body Ruijsenaars operator. The latter is a $q

D. S. McAnally, I. Tsohantjis

The quantum double construction of a $q$-deformed boson algebra possessing a Hopf algebra structure is carried out explicitly. The $R$-matrix thus obtained is compared with the existing literature.

M. B. Barbaro, A. De Pace, T. W. Donnelly, A. Molinari

The extraction of the nucleon&#39;s strangeness axial charge, Delta_s, from inclusive, quasielastic neutral current neutrino cross sections is studied within the framework of the plane-wave impulse approximation. We find that the value of Delta_s can depend significantly on the choice of nuclear model used in analyzing the quasielastic cross section. This mo

Saharon Shelah

We address a number of problems on Boolean Algebras. For example, we construct, in ZFC, for any BA B, and cardinal kappa BAs B_1,B_2 extending B such that the depth of the free product of B_1,B_2 over B is strictly larger than the depths of B_1 and of B_2 than kappa. We give a condition (for lambda, mu and theta) which implies that for some BA A_theta there

Moti Gitik, Saharon Shelah

We give some general criteria, when kappa-complete forcing preserves largeness properties -- like kappa-presaturation of normal ideals on lambda (even when they concentrate on small cofinalities). Then we quite accurately obtain the consistency strength ``NS_lambda is aleph_1-preserving&#39;&#39;, for lambda > aleph_2 .

Ale Jan Homburg

We consider the dynamics of `nonlinear tent maps&#39;: piecewise smooth unimodal maps with nowhere vanishing derivative. We show that if a nonlinear tent map $f$ is not infinitely renormalizable, then all its periodic orbits of sufficiently high period are hyperbolic repelling. If additionally all periodic orbits of $f$ are hyperbolic, then $f$ has at most f

Masaru Kamata, Takao Koikawa

We discuss the exact electrically charged BTZ black hole solutions to the Einstein-Maxwell equations with a negative cosmological constant in 2+1 spacetime dimensions assuming a (anti-)self dual condition between the electromagnetic fields. In a coordinate condition there appears a logarithmic divergence in the angular momentum at spatial infinity. We show h

Burkhard Kleihaus, Jutta Kunz, Abha Sood

Einstein-Yang-Mills-dilaton theory possesses sequences of neutral static spherically symmetric black hole solutions. The solutions depend on the dilaton coupling constant $γ$ and on the horizon. The SU(2) solutions are labelled by the number of nodes $n$ of the single gauge field function, whereas the SO(3) solutions are labelled by the nodes $(n_1,n_2)$ of

S. O. Alexeyev, M. V. Pomazanov

A new numerical integration method for examining a black hole structure was realized. Black hole solutions with dilatonic hair of 4D low energy effective SuperString Theory action with Gauss-Bonnet quadratic curvature contribution were studied, using this method, inside and outside the event horizon. Thermodynamical properties of this solution were also stud