July 1996 arXiv papers — page 13

Y. Sofue, F. Schoeniger, M. Honma, Y. Tutui

We report on the first results of a long-term project to derive distances of galaxies at cosmological distances by applying the CO-line width-luminosity relation. We have obtained deep CO-line observations of galaxies at redshifts up to 29,000 km/s using the Nobeyama 45-m mm-wave Telescope, and some supplementary data were obtained by using the IRAM 30-m tel

Sunggoo Cho, Kwang Sung Park

In recent years, discrete spaces such as graphs attract much attention as models for physical spacetime or as models for testing the spirit of non-commutative geometry. In this work, we construct the differential algebras for graphs by extending the work of Dimakis et al and discuss linear connections and curvatures on graphs. Especially, we calculate connec

Almut Beige, Gerhard C. Hegerfeldt, Dirk G. Sondermann

Short pulses of a probe laser have been used in the past to measure whether a two-level atom is in its ground or excited state. The probe pulse couples the ground state to a third, auxiliary, level of the atom. Occurrence or absence of resonance fluorescence were taken to mean that the atom was found in its ground or excited state, respectively. In this pape

V. V. Dodonov, A. B. Klimov, V. I. Man'ko

The problem of wave packet tunneling from a parabolic potential well through a barrier represented by a power potential is considered in the case when the barrier height is much greater than the oscillator ground state energy, and the difference between the average energy of the packet and the nearest oscillator eigenvalue is sufficiently small. The universa

Giulio Peruzzi, Alberto Rimini

The measurement process for hidden-configuration formulations of quantum mechanics is analysed. It is shown how a satisfactory description of quantum measurement can be given in this framework. The unified treatment of hidden-configuration theories, including Bohmian mechanics and Nelson's stochastic mechanics, helps in understanding the true reasons why

S. Kartal, N. Tsintsadze, V. I. Berezhiani

The dynamics of relativistically strong electromagnetic (EM) wave propagation in hot electron-positron plasma is investigated. The possibility of finding localized stationary structures of EM waves is explored. It is shown that under certain conditions the EM wave forms a stable localized soliton-like structures where plasma is completely expelled from the r

F. Krmpotic, T. T. S. Kuo, A. Mariano, E. J. V. de Passos

The effect of the inclusion of ground state correlations into the QRPA equation of motion for the two-neutrino double beta ($ββ_{2ν}$) decay is carefully analyzed. The resulting model, called renormalized QRPA (RQRPA), does not collapse near the physical value of the nuclear force strength in the particle-particle channel, as happens with the ordinary QRPA.

F. Krmpotic, A. Mariano, T. T. S. Kuo, E. J. V. de Passos

We show how the longstanding problem of the collapse of the charge-exchange QRPA near the physical value of the force strength can be circumvented. This is done by including the effect of ground state correlations into the QRPA equations of motion. The corresponding formalism, called renormalized QRPA, is briefly outlined and its consequences are discussed i

Vincenzo Fiorentini, Donatella Fois, Sabrina Oppo

Ab initio calculations indicate that the ground state for Ga adsorption on Al (100) is on-surface with local unit coverage. On Ga-coated Al (100), the bridge diffusion barrier for Al is large, but the Al$\rightarrow$Ga {\it exchange barrier is zero}: the ensuing incorporation of randomly deposited Al's into the Ga overlayer realizes a percolation network

R. Banerjee, E. C. Marino

We bosonize the Massive Thirring Model in 3+1D for small coupling constant and arbitrary mass. The bosonized action is explicitly obtained both in terms of a Kalb-Ramond tensor field as well as in terms of a dual vector field. An exact bosonization formula for the current is derived. The small and large mass limits of the bosonized theory are examined in bot

P. Di Francesco, O. Golinelli, E. Guitter

We study the statistics of semi-meanders, i.e. configurations of a set of roads crossing a river through n bridges, and possibly winding around its source, as a toy model for compact folding of polymers. By analyzing the results of a direct enumeration up to n=29, we perform on the one hand a large n extrapolation and on the other hand we reformulate the ava

A. A. Bytsenko, S. D. Odintsov, L. N. Granda

Following Polchinski's approach we calculate the one-loop vacuum amplitude for two parallel D-branes connected by open bosonic (neutral or charged)string in a constant uniform electromagnetic (EM) field. For neutral string, external EM field contribution appears as multiplier (Born-Infeld type action) of vacuum amplitude without external EM field. Hence,

G. Amelino-Camelia, I. I. Kogan, R. J. Szabo

We discuss the evaluation of observables in two-dimensional conformal field theory using the topological membrane description. We show that the spectrum of anomalous dimensions can be obtained perturbatively from the topologically massive quantum field theories by computing radiative corrections to Aharonov-Bohm scattering amplitudes for dynamical charged ma

M. R. Gaberdiel

The comultiplication formula for fusion products of untwisted representations of the chiral algebra is generalised to include arbitrary twisted representations. We show that the formulae define a tensor product with suitable properties, and determine the analogue of Zhu's algebra for arbitrary twisted representations. As an example we study the fusion of

C. Quesne

A generalized spin Sutherland model including a three-body potential is proposed. The problem is analyzed in terms of three first-order differential-difference operators, obtained by combining SUSYQM supercharges with the elements of the dihedral group~$D_6$. Three alternative commuting operators are also introduced.

V. A. Tsokur, Yu. M. Zinoviev

In this paper we consider a class of models for vector and hypermultiplets, interacting with $N=2$ supergravity, with gauge groups being an infinite-dimensional Kac-Moody groups. It is shown that specific properties of Kac-Moody groups, allowing the introduction of the vector fields masses without the usual Higgs mechanism, make it possible to break simultan

Andrei M. Sukhov

The theory including interaction between Siegel and gauge multiplets leads to the model of nonbreaking supersymmetry which contains massive scalar, four component fermion and gauge fields. The upper bound of Higgs boson mass is estimated as heaviest fermion mass. The idea to replace Higgs field by scalar superpartner or by auxiliary fields of corresponding s

M. V. Polyakov, C. Weiss

We calculate the vacuum expectation value of the dimension-5 "mixed" quark-gluon operator, $O_σ= \barψ(λ^a /2) σ_{μν} ψF_{μν}^a$, in the instanton vacuum. Within the $1/N_c$--expansion the QCD operator is replaced by an effective many-fermion operator, which is averaged over the effective theory of massive quarks derived from instantons. We find $m_0

Damir Becirevic

The bounds on the form factors for $B \to ρ\ell ν_\ell$ decay are studied. Constrained by lattice data and a constrained conformal mapping, the more informations can be obtained for $A_1(q^2)$ form-factor which dominates the decay rate at large $q^2$. Specifically, we confirm a moderately increasing behavior of this form factor.

Borut Bajc, Alejandra Melfo, Goran Senjanovic

While it is possible to find examples of field theories with a spontaneously broken symmetry at high temperature, in renormalizable supersymmetric models any internal symmetry gets always restored. Recently, a counterexample was suggested in the context of nonrenormalizable supersymmetric theories. We show that non negligible higher loop effects actually res

F. de Campos, S. M. Lietti, S. F. Novaes, R. Rosenfeld

We investigate the existence of anomalous Higgs boson couplings, $Hγγ$ and $HZγ$, through the analysis of the process $e^+ e^- \to γγγ$ at LEP2 energies. We suggest some kinematical cuts to improve the signal to background ratio and determine the capability of LEP2 to impose bounds on those couplings by looking for a Higgs boson signal in this reaction.

N. Armesto, M. A. Braun, E. G. Ferreiro, C. Pajares

It is shown that the critical threshold for percolation of the overlapping strings exchanged in heavy ion collisions can naturally explain the sharp strong suppresion of $J/ψ$ shown by the experimental data on central Pb--Pb collisions, which does not occur in central O--U and S--U collisions.

A. Ringwald, F. Schrempp

We present a brief status report of our broad and systematic study of QCD-instantons at HERA.

L. Bergstrom, J. Edsjo, P. Gondolo

Neutralinos annihilating in the center of the Sun or the Earth may give rise to a detectable signal of neutrinos. We derive the indirect detection rates for neutrino telescopes in the minimal supersymmetric extension of the standard model. We show that even after imposing all phenomenological and experimental constraints that make the theories viable, region

C. S. Kim

We propose a new model-independent method, to determine the ratio $|V_{ub}/V_{cb}|$, which is theoretically described by the phase space factor and the well-known perturbative QCD correction only. We explore the possible experimental options: the measurement of inclusive hadronic invariant mass distributions. We also discuss the relevant experimental backgro

S. Bronoff, C. P. Korthals Altes

The string tension at low T and the free energy of domain walls at high T can be computed from one and the same observable. We show by explicit calculation that domain walls in hot Z(2) gauge theory have good thermodynamical behaviour. This is due to roughening of the wall, which expresses the restoration of translational symmetry.

Paolo Cea, Leonardo Cosmai

We propose a method based on the Schrödinger functional for computing on the lattice the gauge invariant effective action for external background fields. We check this method by studying the U(1) lattice gauge theory in presence of a constant magnetic background field.

D. S. Henty, O. Oliveira, C. Parrinello, S. Ryan

We present an exploratory study of a one-parameter family of covariant, non-perturbative lattice gauge-fixing conditions, that can be implemented through a simple Monte Carlo algorithm. We demonstrate that at the numerical level the procedure is feasible, and as a first application we examine the gauge dependence of the gluon propagator.

Sergio Caracciolo, Andrea Pelissetto

We have considered the corrections to the finite-size-scaling functions for a general class of $O(N)$ $σ$-models with two-spin interactions in two dimensions for $N=\infty$. We have computed the leading corrections finding that they generically behave as $(f(z) \log L + g(z))/L^2$ where $z = m(L) L$ and $m(L)$ is a mass scale; $f(z)$ vanishes for Symanzik im

Giuseppe Burgio, Sergio Caracciolo, Andrea Pelissetto

We describe an algebraic algorithm which allows to express every one-loop lattice integral with gluon or Wilson-fermion propagators in terms of a small number of basic constants which can be computed with arbitrary high precision. Although the presentation is restricted to four dimensions the technique can be generalized to every space dimension. We also giv

Marek Gazdzicki, Dieter Roehrich

Data on the mean multiplicity of strange hadrons produced in minimum bias proton--proton and central nucleus--nucleus collisions at momenta between 2.8 and 400 GeV/c per nucleon have been compiled. The multiplicities for nucleon--nucleon interactions were constructed. The ratios of strange particle multiplicity to participant nucleon as well as to pion multi

A. Fabbri

In this paper we analyse the stability of black hole Cauchy horizons arising in a class of 2d dilaton gravity models. It is shown that due to the characteristic asymptotic Rindler form of the metric of these models, time dependent gravitational perturbations generated in the external region do not necessarily blow-up when propagated along the Cauchy horizon.

R. Balbinot, A. Fabbri

By considering charged black hole solutions of a one parameter family of two dimensional dilaton gravity theories, one finds the existence of quantum mechanically stable gravitational kinks with a simple mass to charge relation. Unlike their Einsteinian counterpart (i.e. extreme Reissner-Nordström), these have nonvanishing horizon surface gravity.

J. F. Barbero G., A. Dominguez, T. Goldman, J. Perez-Mercader

As is well known, structure formation in the Universe at times after decoupling can be described by hydrodynamic equations. These are shown here to be equivalent to a generalization of the stochastic Kardar--Parisi--Zhang equation with time-- dependent viscosity in epochs of dissipation. As a consequence of the Dynamical Critical Scaling induced by noise and

Hermann Bondi, Joseph Samuel

We respond to a recent paper by Rindler on the ``Anti--Machian'' nature of the Lense--Thirring effect. We remark that his conclusion depends crucially on the particular formulation of Mach's principle used.

Gérard Clément

Special multi-cosmic string metrics are analytically extended to describe configurations of Wheeler-Misner wormholes and ordinary cosmic strings. I investigate in detail the case of flat, asymptotically Minkowskian, Wheeler-Misner wormhole spacetimes generated by two cosmic strings, each with tension $-1/4G$.

C. Becker, R. Gielerak, P. Ługiewicz

Covariant stochastic partial differential equations are studied in any dimension. A special class of such equations is selected and it is proven that the solutions can be analytically continued to Minkowski space-time yielding tempered Wightman distributions which are covariant, obey the locality axiom and a weak form of the spectral axiom. Key words: stocha

Stefan Blawid, Hoangh Anh Tuan, Takashi Yanagisawa, Peter Fulde

We investigate the influence of an unoccupied band on the transport properties of a strongly correlated electron system. For that purpose, additional orbitals are coupled to a Hubbard model via hybridization. The filling is one electron per site. Depending on the position of the additional band, both, a metal--to--insulator and an insulator--to--metal transi

Cécile Monthus

We study the following 1D two-species reaction diffusion model : there is a small concentration of B-particles with diffusion constant $D_B$ in an homogenous background of W-particles with diffusion constant $D_W$; two W-particles of the majority species either coagulate ($W+W \longrightarrow W$) or annihilate ($W+W \longrightarrow \emptyset$) with the respe

Raymond E. Goldstein

A simple model is studied for the chemotactic movement of biological cells in the presence of a periodic chemical wave. It incorporates the feature of adaptation that may play an important role in allowing for ``rectified" chemotaxis: motion opposite the direction of wave propagation. The conditions under which such rectification occurs are elucidated in

P. Singh, M. K. Hassan

We present two classes of exact solutions to a geometric model which describes the kinetics of fragmentation of $d$-dimensional hypercuboid-shaped objects. The first class of exact solutions is described by a fragmentation rate $a({x_1},...,{x_d}) = 1$ and daughter distribution function $b({x_1},..,{x_d} | {{x_{1}^{\p}}},...,{{x_{d}^{\p}}})= {(\a_1 + 2)x_1^{

Jeferson J. Arenzon, Mario Nicodemi, Mauro Sellitto

We study the equilibrium properties of an Ising frustrated lattice gas with a mean field replica approach. This model bridges usual {\em Spin Glasses} and a version of {\em Frustrated Percolation} model, and has proven relevant to describe the glass transition. It shows a rich phase diagram which in a definite limit reduces to the known Sherrington-Kirkpatri

Jack Lidmar, Mats Wallin

We study the classical two-dimensional Coulomb gas model for thermal vortex fluctuations in thin superconducting/superfluid films by Monte Carlo simulation of a grand canonical vortex ensemble defined on a continuum. The Kosterlitz-Thouless transition is well understood at low vortex density, but at high vortex density the nature of the phase diagram and of

Hiyan Alshawi

This paper presents statistical language and translation models based on collections of small finite state machines we call ``head automata''. The models are intended to capture the lexical sensitivity of N-gram models and direct statistical translation models, while at the same time taking account of the hierarchical phrasal structure of language. T

R. F. Silverberg, E. S. Cheng, D. A. Cottingham, D. J. Fixsen

Observations from the first flight of the Medium Scale Anisotropy Measurement (MSAM1-92) are analyzed to search for the Sunyaev-Zel'dovich (SZ) effect towards the Coma cluster. This balloon-borne instrument uses a $28\arcmin$ FWHM beam and a three position chopping pattern with a throw of $\pm40\arcmin$. With spectral channels at 5.7, 9.3, 16.5, and 22.6

A. Finoguenov, W. Forman, C. Jones

We analyze diffuse X-ray emission from NGC4649, NGC5044 and NGC5846, combining data from two X-ray observatories, ROSAT and ASCA. With ASCA, we perform a detailed analysis of the X-ray emission which properly accounts for the ASCA PSF and also include a 3-dimensional source model. All three sources exhibit cooling flows in their centers. From the derived abu

J. H. Knapen, J. E. Beckman

We study star formation processes in the disc of the weakly barred grand design spiral galaxy M100 (NGC 4321) from a variety of images tracing recent massive star formation, old and young stars, dust, and neutral hydrogen. Differences between arm and interarm regions are specifically studied by decomposing the images into arm and non-arm zones. We find from

L. Feretti, H. Boehringer, G. Giovannini, D. Neumann

New radio and X-ray data are reported for the rich cluster Abell 2255. The cluster radio emission is characterized by the presence of a diffuse halo source, located at the cluster center, and a more peripheral ridge of radio emission which could be a relic. In addition, 6 tailed radio sources and a small double are found to be associated with cluster galaxie

Claudia S. Moeller, Uta Fritze v. - Alvensleben, Klaus J. Fricke

With a chemically consistent evolutionary synthesis approach we follow the enrichment of individual chemical elements in the ISM. We describe the time With a chemically consistent evolutionary synthesis approach we follow the enrichment of individual chemical elements in the ISM. We describe the time evolution of broad band colors U to K and metal indices (F

D. J. Bomans, K. S. de Boer, J. Koornneef, E. K. Grebel

High resolution ultraviolet spectra with HST-GHRS of two stars in the direction of the supergiant shell LMC4 unambiguously show absorption by substantial quantities of CIV gas at velocities near the the systemic velocity of the LMC. In combination with the detection of diffuse X-rays from the LMC4 by ROSAT and other supporting data, this demonstrates that th

Bernd Kreussler

We study the algebraic dimension of twistor spaces of positive type over $4\bbfP^2$. We show that such a twistor space is Moishezon if and only if its anticanonical class is not nef. More precisely, we show the equivalence of being Moishezon with the existence of a smooth rational curve having negative intersection number with the anticanonical class. Furthe

Fabrizio Catanese, Sandro Manfredini

The Noether-Horikawa surfaces are the minimal surfaces S with K^2=2p_g-4. For 8 | K^2 they belong to two families of respective type C and N (connected, resp. non connected branch locus for the canonical map). For 16 | K^2 the two types are homeomorphic. Ulf Persson constructed surfaces of type N with a maximally singular canonical model X, whose topology en

P. Fre', L. Girardello, I. Pesando, M. Trigiante

Generic partial supersymmetry breaking of $N=2$ supergravity with zero vacuum energy and with surviving unbroken arbitrary gauge groups is exhibited. Specific examples are given.

B. Blok, J. G. Körner, D. Pirjol, J. C. Rojas

We present a complete analysis of the Heavy Quark Effective Theory Lagrangian at order $1/m^2$ in the leading logarithmic approximation, including effects induced by spectator quarks. At this order new correction terms appear in the effective Lagrangian, as four-quark operators containing both heavy and light quark fields. We compute the coefficients of thes

Philippe Droz-Vincent

A (globally) neutral two-body system is supposed to obey a pair of coupled Klein-Gordon equations in a constant homogeneous magnetic field. Considering eigenstates of the pseudomomentum four-vector, we reduce these equations to a three-dimensional eigenvalue problem. The frame adapted to pseudomomentum has in general a nonvanishing velocity with respect to t

M. K. Hassan

We study the kinetics of random sequential adsorption of a mixture of particles with continuous distribution of sizes for different deposition rules. It appears in the long time limit the resulting system can be described using the fractal concept. We reveal that the fractal dimension increases with the degree of increasing order.

Uma Mahanta

In standard ETC models the sideways and diagonal ETC interactions contribute to $δR_b$ with opposite signs. The aim of this article is to study the implications of the CDF value for m_t and the LEP value for R_b on $zt\bar{t}$ couplings where the LH sideways and diagonal ETC effects interfere constructively. We find that for m_t=175 Gev, $δR_b =.0022$ and m^

P. Exner, R. Gawlista, P. Šeba, M. Tater

We study the behavior of a quantum particle confined to a hard--wall strip of a constant width in which there is a finite number $ N $ of point perturbations. Constructing the resolvent of the corresponding Hamiltonian by means of Krein's formula, we analyze its spectral and scattering properties. The bound state--problem is analogous to that of point intera

F. Buccella, S. Esposito, C. Gualdi, G. Miele

The distortions in the thermal energy spectra for neutrinos produced in a supernova when a resonant oscillation, MSW effect, occurs are determined. In order to show this effect for some relevant and representative examples of unified gauge models, we have chosen $SO(10)$, and $SU(5)_{SUSY}$, $SO(10)_{SUSY}$ with a particular scheme for fermion masses (DHR mo

L. A. Dickey, W. Strampp

Some new formulas for the KP hierarchy are derived from the differential Fay identity. They proved to be useful for the $k$-constrained hierarchies providing a series of determinant identities for them. A differential equation is introduced which is called ``universal" since it plays an important role for all the $k$-constrained hierarchies. In the cases

A. Ramos, M. J. Vicente-Vacas, E. Oset

We have determined the spectra of neutrons and protons following the decay of $Λ$ hypernuclei through the one- and two-nucleon induced mechanisms. The momentum distributions of the primary nucleons are calculated and a Monte Carlo simulation is used to account for final state interactions. From the spectra we calculate the number of neutrons ($N_n$) and prot

M. Effenberger, A. Hombach, S. Teis, U. Mosel

We calculate the total photoabsorption cross section on nuclei in the energy range from 300 MeV to 1 GeV within the framework of a semi-classical phase space model. Besides medium modifications like Fermi motion and Pauli blocking we focus on the collision broadening of the involved resonances. The resonance contributions to the elementary cross section are

A. I. L'vov, S. Scopetta, D. Drechsel, S. Scherer

We discuss a possibility to measure the spin-dependent part of the forward Compton scattering amplitude through interference effects of the Bethe-Heitler and virtual Compton scattering mechanisms in photoproduction of e+e- pairs at small angles.

Eric Bedford, John Smillie

In this paper we continue our study of polynomial diffeomorphisms of C^2. Let us recall that there is an invariant measure $μ$, which is the pluri-complex version of the harmonic measure of the Julia set for polynomial maps of C. In this paper we give an integral formula for the Lyapunov exponents of a polynomial automorphism with respect to $μ$ analogous to

Alexander Antonov

In this paper we explicitly prove that Integrable System solved by Quantum Inverse Scattering Method can be described with the pure algebraic object (Universal R-matrix) and proper algebraic representations. Namely, on the example of the Quantum Volterra model we construct L-operator and fundamental R--matrix from universal R--matrix for Quantum Affine $U_q(

M. Alvarez, J. M. F. Labastida, E. Perez

The general structure of the perturbative expansion of the vacuum expectation value of a product of Wilson-loop operators is analyzed in the context of Chern-Simons gauge theory. Wilson loops are opened into Wilson lines in order to unravel the algebraic structure encoded in the group factors of the perturbative series expansion. In the process a factorizati

C. D. D. Neumann

In this paper the elliptic genus for a general Calabi-Yau fourfold is derived. The recent work of Kawai calculating N=2 heterotic string one-loop threshold corrections with a Wilson line turned on is extended to a similar computation where K3 is replaced by a general Calabi-Yau 3- or 4-fold. In all cases there seems to be a generalized Kac-Moody algebra invo

N. Itzhaki

We show that the S-matrix ansatz implies a semi-classical metric such that a freely falling test particle will not cross the horizon in its proper time. Instead of reaching the singularity it will reach ${\cal I^{+}}$.

H. Lu, C. N. Pope

We construct $(D-3)$-brane and instanton solutions using $N \le 10-D$ one-form field strengths in $D$ dimensions, and show that the equations of motion can be cast into the form of the $SL(N+1,R)$ Toda equations. For generic values of the charges, the solutions are non-supersymmetric; however, they reduce to the previously-known multiply-charged supersymmetr

R. Dijkgraaf, E. Verlinde, H. Verlinde

We present a microscopic index formula for the degeneracy of dyons in four-dimensional N=4 string theory. This counting formula is manifestly symmetric under the duality group, and its asymptotic growth reproduces the macroscopic Bekenstein-Hawking entropy. We give a derivation of this result in terms of the type II five-brane compactified on K3, by assuming

C. G. Bollini L. E. Oxman, M. C. Rocca

A scalar field obeying a Lorentz invariant higher order wave equation, is minimally coupled to the electromagnetic field. The propagator and vertex factors for the Feynman diagrams, are determined. As an example we write down the matrix element for the Compton effect. This matrix element is algebraically reduced to the usual one for a charged Klein-Gordon pa

C. G. Bollini, M. C. Rocca

We show that the anomalies of the Virasoro algebra are due to the asymmetric behavior of raising and lowering operators with respect to the ground state of the string. With the adoption of a symmetric vacuum we obtain a non-anomalous theory in any number of dimensions. In particular for D=4.

C. G. Bollini, M. C. Rocca

We suggest that the Higgs might be unobservable as a free particle, due to its origin at a symmetry breaking mechanism. The standard model is kept intact, only the definition of the vacuum for the Higgs is changed. With the new (natural) definition, the Higgs propagator is half advanced and half retarded. This Green function is compatible with the absence of

Csaba Csaki, Lisa Randall, Witold Skiba, Robert Leigh

We show that theories in the confining, free magnetic, and conformal phases can break supersymmetry through dynamical effects. To illustrate this, we present theories based on the gauge groups $SU(n)\times SU(4)\times U(1)$ and $SU(n) \times SU(5) \times U(1)$ with the field content obtained by decomposing an $SU(m)$ theory with an antisymmetric tensor and $

Ori J. Ganor

Compactifying the $E_8$ non-critical string in 6D down to 5D the 6D strings give rise to particles and strings in 5D. Using the dual M-theory description compactified on an elliptically fibered Calabi-Yau we compare some of the 5D BPS states to what one expects from non-critical strings with an $E_8$ chiral current algebra. The $E_8$ multiplets of particle s

Tapobrata Sarkar, Rahul Basu

In the kinematic region of small $x$ and large $Q^2$ in deep inelastic scattering, presently being explored by HERA, we present an analysis of the evolution of the longitudinal structure function $F_L^{p}(x, Q^2)$ in the double scaling limit of Ball and Forte. We fit the evolution to a $1/x^λ$ behaviour and extract the value of $λ$. We also study the behavio

J. Lopez

We summarize recent developments in the prediction for $α_s(M_Z)$, self-consistent string unification and the dynamical determination of mass scales, and leptophobic $Z'$ gauge bosons in the context of stringy flipped SU(5). [To appear in Proceedings of Fourth International Conference on Supersymmetry (SUSY96), University of Maryland (May 1996).]

N. G. Stefanis

A selected set of topics along the borderline between perturbative and nonperturbative QCD in exclusive reactions are studied. Specific problems, related to different mechanisms of momentum transfer to an intact hadron, are discussed. Calculations of the space-like form factors of the pion and the nucleon are reviewed within a convolution scheme of short-dis

I. A. Korchemskaya, G. P. Korchemsky

Analysing the asymptotic behaviour of the quark-quark elastic scattering amplitude at high energy and fixed transferred momentum and assuming that gluon is reggeized, we obtain the evolution equation for the gluon Regge trajectory in QCD. It is closely related to the renormalization properties of the Wilson lines and it is in a complete agreement with the re

A. B. Arbuzov, V. S. Fadin, E. A. Kuraev, L. N. Lipatov

We present the calculation of the elastic and inelastic high--energy small--angle electron--positron scattering with a {\it per mille} accuracy. PACS numbers 12.15.Lk, 12.20.--m, 12.20.Ds, 13.40.--f

David Makovoz

We use Bayes' probability theorem to analyze many-pole fits of hadron propagators. An alternative method of estimating values and uncertainties of the fit parameters is offered, which has certain advantages over the conventional methods. The probability distribution of the parameters of a fit is calculated. The relative probability of various models is c

Giuseppe Burgio, Sergio Caracciolo, Andrea Pelissetto

We describe an algebraic algorithm which allows to express every one-loop lattice integral with gluon or Wilson-fermion propagators in terms of a small number of basic constants which can be computed with arbitrary high precision. Although the presentation is restricted to four dimensions the technique can be generalized to every space dimension. Various exa

W. Kerler, C. Rebbi, A. Weber

Our study of the energy distribution has shown that the strength of the first order transition in the four-dimensional compact U(1) lattice gauge theory decreases when the coupling $λ$ of the monopole term increases. The disappearance of the energy gap for sufficiently large values of $λ$ indicates that the transition ultimately becomes of second order. In o

F. Abe

We report a measurement of the ratios of the decay rates of the B^+, B^0 and B^0_s mesons into exclusive final states containing a J/psi meson. The final states were selected from 19.6 pb^{-1} of p-pbar collisions recorded by the Collider Detector at Fermilab. These data are interpreted to determine the bquark fragmentation fractions f_u, f_d and f_s. We als

Andrew Abrahams, Arlen Anderson, Yvonne Choquet-Bruhat, James W. York,

We obtain a system for the spatial metric and extrinsic curvature of a spacelike slice that is hyperbolic non-strict in the sense of Leray and Ohya and is equivalent to the Einstein equations. Its characteristics are the light cone and the normal to the slice for any choice of lapse and shift functions, and it admits a well-posed causal Cauchy problem in a G

A. Y. Shiekh

It is well known that Einstein gravity is non-renormalizable; however this does not preclude the existence of a quantum form.

A. Błaut, J. Kowalski--Glikman

We construct the regularized Wheeler--De Witt operator demanding that the algebra of constraints of quantum gravity is anomaly free. We find that for only a small subset of all wavefunctions being integrals of scalar densities this condition can be satisfied. It turns out that the resulting operator is much simpler than the one used in \cite{JK} to find exac

Victor Nistor

We compute the equivariant cohomology Chern character of the index of elliptic operators along the leaves of the foliation of a flat bundle. The proof is based on the study of certain algebras of pseudodifferential operators and uses techniques for analizing noncommutative algebras similar to those developed in Algebraic Topology, but in the framework of cyc

L. A. Mirny, E. I. Shakhnovich

In this paper we introduce a novel method of deriving a pairwise potential for protein folding. The potential is obtained by optimization procedure, which simultaneously maximizes the energy gap for {\it all} proteins in the database. To test our method and compare it with other knowledge-based approaches to derive potentials, we use simple lattice model. In

S. John Di Bartolo, Alan T. Dorsey

Using the time-dependent Ginzburg-Landau equations we study the propagation of planar fronts in superconductors, which would appear after a quench to zero applied magnetic field. Our numerical solutions show that the fronts propagate at a unique speed which is controlled by the amount of magnetic flux trapped in the front. For small flux the speed can be det

Manfred Salmhofer

The naive perturbation expansion for many-fermion systems is infrared divergent. One can remove these divergences by introducing counterterms. To do this without changing the model, one has to solve an inversion equation. We call this procedure Fermi surface renormalization (FSR). Whether or not FSR is possible depends on the regularity properties of the fer

M. B. Hastings, L. S. Levitov

A new model of Laplacian stochastic growth is formulated using conformal mappings. The model describes two growth regimes, stable and turbulent, separated by a sharp phase transition. The first few Fourier components of the mapping define the web, an envelope of the cluster. The web is used to study the transition and the dynamics of large-scale features of

Erik Luijten, Henk W. J. Blöte, Kurt Binder

We study the crossover from Ising-like to classical critical behavior as a function of the range R of interactions. The power-law dependence on R of several critical amplitudes is calculated from renormalization theory. The results confirm the predictions of Mon and Binder, which were obtained from phenomenological scaling arguments. In addition, we calculat

G. Casati, B. V. Chirikov, I. Guarneri, F. M. Izrailev

First theoretical and numerical results on the global structure of the energy shell, the Green function spectra and the eigenfunctions, both localized and ergodic, in a generic conservative quantum system are presented. In case of quantum localization the eigenfunctions are shown to be typically narrow and solid, with centers randomly scattered within the se

P. Exner, P. Šeba

In addition to the conventional renormalized--coupling--constant picture, point interactions in dimension two and three are shown to model within a suitable energy range scattering on localized potentials, both attractive and repulsive.

Vidar Gudmundsson, Rolf R. Gerhardts

The far-infrared absorption of a two-dimensional electron gas with a square-lattice modulation in a perpendicular constant magnetic field is calculated self-consistently within the Hartree approximation. For strong modulation and short period we obtain intra- and intersubband magnetoplasmon modes reflecting the subbands of the Hofstadter butterfly in two or

Martin Greiter

In order to obtain a local description of the short distance physics of fractionally quantized Hall states for realistic (e.g. Coulomb) interactions, I propose to view the zeros of the ground state wave function, as seen by an individual test electron from far away, as particles. I then present evidence in support of this interpretation, and argue that the e

Hiyan Alshawi

We present a language model consisting of a collection of costed bidirectional finite state automata associated with the head words of phrases. The model is suitable for incremental application of lexical associations in a dynamic programming search for optimal dependency tree derivations. We also present a model and algorithm for machine translation involvi

Takashi Nishikawa, Kunihiko Kaneko

Fractalization of torus and its transition to chaos in a quasi-periodically forced logistic map is re-investigated in relation with a strange nonchaotic attractor, with the aid of functional equation for the invariant curve. Existence of fractal torus in an interval in parameter space is confirmed by the length and the number of extrema of the torus attracto

Victor S. L'vov, Itamar Procaccia

It is shown that the idea that scaling behavior in turbulence is limited by one outer length $L$ and one inner length $η$ is untenable. Every n'th order correlation function of velocity differences $\bbox{\cal F}_n(\B.R_1,\B.R_2,\dots)$ exhibits its own cross-over length $η_{n}$ to dissipative behavior as a function of, say, $R_1$. This length depends on