October 1997 arXiv papers

G. J. Mathews, P. Marronetti, J. R. Wilson

We discuss the underlying relativistic physics which causes neutron stars to compress and collapse in close binary systems as has recently been observed in numerical (3+1) dimensional general relativistic hydrodynamic simulations. We show that compression is driven by velocity-dependent relativistic hydrodynamic terms which increase the self gravity of the s

R. L. Jaffe, Xuemin Jin, Jian Tang

We explore further applications of the twist-two quark interference fragmentation functions introduced earlier. We show that semi-inclusive production of two pions in the current fragmentation region in deep inelastic scattering of a longitudinally polarized electron on a longitudinally polarized nucleon can provide a probe of the valence quark spin (or heli

Francesco Vissani, Alexei Yu. Smirnov

The atmospheric neutrinos produce isolated neutral pions ($π^0$-events) mainly in the neutral current interactions. We propose to study the ratios involving $π^0$-events and the events induced mainly by the charged currents. This minimizes uncertainties related to the original neutrino fluxes, and in certain cases, also to the cross-sections. Experimental st

Andrea Cappelli, Paolo Valtancoli, Luca Vergnano

The Seiberg-Witten solution of N=2 supersymmetric SU(2) gauge theories with matter is analysed as an isomonodromy problem. We show that the holomorphic section describing the effective action can be deformed by moving its singularities on the moduli space while keeping their monodromies invariant. Well-known examples of isomonodromic sections are given by th

A. Dedes, C. Panagiotakopoulos, K. Tamvakis

We study the generation of the GUT scale through radiative corrections in the context of a R-symmetric "flipped" SU(5) X U(1)_X model. A negative mass squared term for the GUT Higgs fields develops due to radiative effects along a flat direction at a superheavy energy scale. The R-symmetry is essential in maintaining triplet-doublet splitting and F-f

D. Matalliotakis, H. P. Nilles, S. Theisen

We give a detailed discussion of the matching of the BPS states of heterotic, type I and type I' theories in d=9 for general backgrounds. This allows us to explicitly identify these (composite) brane states in the type I' theory that lead to gauge symmetry enhancement at critical points in moduli space. An example is the enhancement of $SO(16)\times

T. Christen, M. Buttiker

This work addresses nucleation rates in systems with strong initial recombination. Initial (or `geminate') recombination is a process where a dissociated structure (anion, vortex, kink etc.) recombines with its twin brother (cation, anti-vortex, anti-kink) generated in the same nucleation event. Initial recombination is important if there is an asymptoti

DZERO Collaboration, B. Abbott

We have searched for first generation scalar leptoquark (LQ) pairs in the enu+jets channel using ppbar collider data (integrated luminosity= 115 pb^-1) collected by the DZero experiment at the Fermilab Tevatron during 1992-96. The analysis yields no candidate events. We combine the results with those from the ee+jets and nunu+jets channels to obtain 95% conf

Tom Banks

This is an expanded version of talks given by the author at the Trieste Spring School on Supergravity and Superstrings in April of 1997 and at the accompanying workshop. The manuscript is intended to be a mini-review of Matrix Theory. The motivations and some of the evidence for the theory are presented, as well as a clear statement of the current puzzles ab

David J. Gross, Akikazu Hashimoto, Igor R. Klebanov

We study the spectrum of 1+1 dimensional large $N$ QCD coupled to an adjoint Majorana fermion of mass $m$. As $m\to 0$ this model makes a transition from confinement to screening. We argue that in this limit the spectrum becomes continuous for mass greater than twice the mass of the lightest bound state. This critical mass is nothing but the threshold for a

L. A. Dickey

Isomonodromic deformations are nothing but symmetries of the Zakharov-Shabat (isospectral) hierarchy, both the basic ones (belonging to the hierarchy) and additional, restricted to the submanifold of solutions to the string equation.

Q. P. Liu, Manuel Manas

Several types of Darboux transformations for supersymmetric integrable systems such as the Manin-Radul KdV, Mathieu KdV and SUSY sine-Gordon equations are considered. We also present solutions such as supersolitons and superkinks.

J. C. Brunelli, Ashok Das

We construct a zero curvature formulation, in superspace, for the sTB-B hierarchy which naturally reduces to the zero curvature condition in terms of components, thus solving one of the puzzling features of this model. This analysis, further, suggests a systematic method of constructing higher dimensional representations for the zero curvature condition star

Hideaki Aoyama, Hisashi Kikuchi, Ikuo Okouchi, Masatoshi Sato

Conventionally, perturbative and non-perturbative calculations are performed independently. In this paper, valleys in the configuration space in quantum mechanics are investigated as a way to treat them in a unified manner. All the known results of the interplay of them are reproduced naturally. The prescription for separating the non-perturbative contributi

E. Mukhin, A. Varchenko

We consider the discrete Knizhnik-Zamolodchikov connection (qKZ) associated to $gl(N)$, defined in terms of rational R-matrices. We prove that under certain resonance conditions, the qKZ connection has a non-trivial invariant subbundle which we call the subbundle of quantized conformal blocks. The subbundle is given explicitly by algebraic equations in terms

Masahiko Miyamoto

We define an automorphism of VOA of order 3 by using a sub VOA isomorphic to a direct sum of 3-state Potts models $L(\ff,0)$ and an its module $L(\ff,3)$. This automorphism is a 3A element of the monster simple group if $V$ is the moonshine VOA $V^{\natural}$.

A. Kievsky, E. Pace, G. Salme`, M. Viviani

The investigation of the electromagnetic inclusive responses of polarized $^{3}$He within the plane wave impulse approximation is briefly reported. A particular emphasys is put on the extraction, from the inclusive responses at the quasielastic peak, of the neutron form factors from feasible experiments.

P. F. Bedaque, U. van Kolck

We use an effective field theory to compute low-energy nucleon-deuteron scattering. We obtain the quartet scattering length using low energy constants entirely determined from low-energy nucleon-nucleon scattering. We find $a_{th}=6.33$ fm, to be compared to $a_{exp}=6.35\pm 0.02$ fm.

Antônio Sá Barreto, Mark Joshi

The problem of recovering the asymptotics of a short range perturbation of the Euclidean metric on R^n from fixed energy scattering data is studied. It is shown that if two such metrics, g1, g2, have scattering data at some fixed energy which are equal up to smoothing, then there exists a diffeomorphism ψ`fixing infinity' such that ψ^*(g1) - g2 is rapidl

W. Lerche

After briefly reviewing basic concepts of perturbative string theory, we explain in simple terms some of the new findings that created excitement among the string physicists. These developments include non-perturbative dualities and a unified picture that embraces the so-far known theories. (An overview for non-experts)

M. S. Bremer, H. Lu, C. N. Pope, K. S. Stelle

We present the form of the Dirac quantisation condition for the p-form charges carried by p-brane solutions of supergravity theories. This condition agrees precisely with the conditions obtained in lower dimensions, as is necessary for consistency with Kaluza-klein dimensional reduction. These considerations also determine the charge lattice of BPS soliton s

I. V. Lavrinenko, H. Lu, C. N. Pope

We study some geometrical and topological aspects of the generalised dimensional reduction of supergravities in D=11 and D=10 dimensions, which give rise to massive theories in lower dimensions. In these reductions, a global symmetry is used in order to allow some of the fields to have a non-trivial dependence on the compactifying coordinates. Global consist

M. G. Ivanov

Generalization of harmonic superposition rule for the case of dependent choice of harmonic functions is given. Dependence of harmonic functions from all (relative and overall) transverse coordinates is considered using the Beltrami-Laplace operator. Supersymmetry of IIB 10D supergravity solutions with only non-vanished 5-form field and 11D supergravity solut

S. Riemann

The search for a Z' is one of the tasks of future colliders. I study the capability to detect the Z' at a linear e+e- collider operating below resonance production. Depending on m_{\Zp} and the collider parameters we will be able to discriminate between Z' models.

S. Bellucci

$N=2,8$ supergravity predicts antigravity (gravivector and graviscalar) fields in the graviton supermultiplet. Data on the binary pulsar PSR 1913+16, tests of the equivalence principle and searches for a fifth force yield an upper bound of order 1 meter (respectively, 100 meters) on the range of the gravivector (respectively, graviscalar) interaction. Hence

Gerhard Ecker

Elastic pion-pion and pion-nucleon scattering are reviewed in the context of chiral perturbation theory. Theoretical results from systematic low-energy expansions to O(p^6) for pion-pion and to O(p^3) for pion-nucleon scattering are compared with experimental data. Possible future developments are outlined.

M. Scorletti

This talks examines the effect of angular ordering on the small-x evolution of the unintegrated gluon distribution, and discusses the characteristic function for the CCFM equation.

Nora Brambilla, Antonio Vairo

We obtain the non-perturbative interaction kernel of the heavy-light quark system in a gauge-invariant approach. The potential and the sum rules limit are discussed. Some insight is given in the light quark interaction.

J. A. Oller, E. Oset

We present a unified picture which studies simultaneously the gamma gamma--> pi^+ pi^-, pi^0 pi^0,K^+ K^-, K^0 bar{K}^0, pi^0 eta reactions up to about sqrt(s)=1.4 GeV reproducing the experimental cross sections. The present work implements in an accurate way the final state interactions of the meson-meson system, which is shown to be essential in order to r

S. Mallik

We extend an earlier, configuration space method to find the Wilson coefficients of operators appearing in the short distance expansion of thermal correlation functions of different quark bilinears. Considering all the different correlation functions, there arise, up to dimension four, two new operators, in addition to the two appearing already in the vacuum

J. Bijnens, G. Colangelo, G. D'Ambrosio, F. Gabbiani

This is the summary of the working group on Goldstone Boson Production and Decay of the Chiral Dynamics Workshop in Mainz, September 1-5, 1997. For the production aspects we discuss $π^0$ and $η$ production in nucleon-nucleon collisions and the behaviour of hadrons in various sum rules. For the decays we present a discussion on various $K$, $η$ and $π$ decay

J. A. Oller, E. Oset

We use a non-perturbative approach which combines coupled channel Lippmann-Schwinger equations with meson-meson potentials provided by the lowest order chiral Lagrangian. By means of one parameter, a cut off in the momentum of the loop integrals, which results of the order of 1 GeV, we obtain singularities in the S-wave amplitudes corresponding to the sigma,

A. Yu. Ignatiev, G. C. Joshi

We examine several issues related to the processes of Dirac monopole-antimonopole production in high-energy collisions such as $e^+e^-$ annihilation. Perturbative calculations for such processes are known to be inherently ambiguous due to the arbitrariness of direction of the monopole string; this requires use of some prescription to obtain physical results.

A. Yu. Ignatiev, G. C. Joshi

Hybrid $SU(2) \times U(1)$ models are the models in which $SU(2) \times U(1)$ symmetry is broken down not only spontaneously (as in the Standard Model), but also explicitely by adding a hard mass term for the U(1) field in the lagrangian. We study the issue of electric charge nonconservation and dequantization in these models. For this purpose we construct a

Xiao-Gang He

In this lecture I review the present status of CP violation in the Standard Model and some of its extensions and discuss ways to distinguish different models. Contents 1. Introduction 2. CP violation in the Standard Model 3. Test the Standard Model in B decays 4. Models for CP violation 5. The KM unitarity triangle and new physics 6. Direct CP violation in n

J. Hein, A. Ali Khan, T. Bhattacharya, S. Collins

We present results on the spectrum of B and D mesons including radial excitations and discuss the pseudoscalar decay constant. The results are obtained at beta=5.7 in the quenched approximation using NRQCD for the heavy quark. To study scaling violations we also compare to results obtained at beta=6.0.

H. Burton, R. B. Mann

We consider a Palatini variation on a general $N$-Dimensional second order, torsion-free dilaton gravity action and determine the resulting equations of motion. Consistency is checked by considering the restraint imposed due to invariance of the matter action under simple coordinate transformations, and the special case of N=2 is examined. We also examine a

R. Gomez, L. Lehner, R. L. Marsa, J. Winicour

We model a radiating, moving black hole in terms of a worldtube-nullcone boundary value problem. We evolve this data in the region interior to the worldtube but exterior to a trapped surface by means of a characteristic evolution based upon a family of ingoing null hypersurfaces. Data on the worldtube is induced from a Schwarzschild spacetime but the worldtu

Rosario Martin, Enric Verdaguer

The Einstein-Langevin equation is a perturbative correction to the semiclassical Einstein equation which takes into account the lowest order quantum fluctuations of the matter stress-energy tensor. It predicts classical stochastic fluctuations in the metric field which may describe some of the remnant gravitational fluctuations after the process of environme

A. Blaut, J. Kowalski-Glikman

We use the quantum potential approach to analyse the quantum cosmological model of the universe. The quantum potential arises from exact solutions of the full Wheeler-De Witt equation.

Roy Maartens, Megan Govender, Sunil Maharaj

We find a simple inflationary solution in an inhomogeneous spacetime with heat flux. The heat flux obeys a causal transport equation, and counteracts the inflationary decrease of energy density. At late times, the heat flux tends to zero and the fluid approaches the equation of state $p=-ρ$.

Benjamin J. Owen, Hideyuki Tagoshi, Akira Ohashi

We derive all second post-Newtonian (2PN), non-precessional effects of spin- orbit coupling on the gravitational wave forms emitted by an inspiraling binary composed of spinning, compact bodies in a quasicircular orbit. Previous post- Newtonian calculations of spin-orbit effects (at 1.5PN order) relied on a fluid description of the spinning bodies. We simpli

J. J. Palacios, A. H. MacDonald

We discuss the charge distributions across the bulk of a two-dimensional electron gas system which is on an integer or fractional quantum Hall plateau. Our analysis is based on a relation, derived from the long wavelength limit of the bulk density-density response function, between the induced charge and leading derivatives of a slowly varying Hall potential

T. C. Lubensky, A. B. Harris, Randall D. Kamien, Gu Yan

Molecular chirality leads to a wonderful variety of equilibrium structures, from the simple cholesteric phase to the twist-grain-boundary phases, and it is responsible for interesting and technologically important materials like ferroelectric liquid crystals. This paper will review some recent advances in our understanding of the connection between the chira

Tao Sun, Anna C. Balazs, David Jasnow

We study the dynamics of the phase behavior of a polymer blend in the presence of shear flow. By adopting a two fluid picture and using a generalization of the concept of material derivative, we construct kinetic equations that describe the phase behavior of polymer blends in the presence of external flow. A phenomenological form for the shear modulus for th

A. A. Shanenko

A new approach developed by A. Shanenko [Phys. Lett. A 227 (1997) 367] for investigating the spatial boson correlations at low temperatures is considered in the particular case of the Coulomb interaction potential. This approach is based on integro-differential equations for the radial distribution function and can be used beyond the weak coupling regime.

V. I. Yukalov, E. P. Yukalova

An approach is developed, combining the ideas of quantum statistical mechanics and multichannel theory of scattering, for treating statistical systems whose constituents can possess different bound states realized as compact clusters. The main principles for constructing multichannel cluster Hamiltonians are formulated: principle of statistical correctness,

A. Yu. Cherny, A. A. Shanenko

The model recently proposed by A.A. Shanenko [Phys. Lett. A 227 (1997) 367] is used to derive linear integro-differential equations whose solutions provide reasonable estimates for the momentum distribution and condensate fraction in interacting many-boson system at zero temperature. An advantage of these equations is that they can be employed in the weak co

Peter Stahl

According to the Kosterlitz-Thouless-Theory two-dimensional solid films melt by the unbinding of dislocation pairs. A model including quenched random impurities was already studied by Nelson [Phys. Rev. B 27 (1983) 2902], who predicted a reentrance into the disordered phase at low temperatures and weak disorder. New investigations of the physically related X

K. Schoenhammer

A simple model of noninteracting electrons with a separable one-body potential is used to discuss the possible pole structure of single particle Green's functions for fermions on unphysical sheets in the complex frequency plane as a function of the system parameters. The poles in the exact Green's function can cross the imaginary axis, in contrast to

Ken-ichiro Imura, Naoto Nagaosa

Tunneling conductance $G(T)$ through a constricted point contact is studied for the $ν=2/3$ spin-singlet edges. Including spin-flip tunneling, Zeeman splitting and random magnetic impurities, we discuss the various crossovers of $G(T)$ as a function of the temperature $T$. The behavior of $G(T)$ is found to be quite different for spin-singlet and spin-polari

Antal Karolyi, Janos Kertesz

A granular media lattice gas (GMLG) model is used to study avalanches in a two-dimensional granular pile. We demonstrate the efficiency of the algorithm by showing that several features of the non-critical behaviour of real sandpile surfaces, such as the bounded outflow statistics or the finite-size effect of the time evolution of the pile mass, can be repro

Chee Kwan Gan, Jian-Sheng Wang

We express the coverage (occupation fraction) $θ$, in powers of time $t$ for four models of two-dimensional lattice random sequential adsorption (RSA) to very high orders by improving an algorithm developed by the present authors [J. Phys. A 29, L177 (1996)]. Each of these series is, to the best of our knowledge, the longest at the present. We analyze the se

Alexander V. Efanov

The N-vortex solutions to the two-dimensional Ginzburg - Landau equations for the kappa=1/\sqrt(2) parameter are built. The exact solutions are derived for the vortices with large numbers of the magnetic flux quanta. The size of vortex core is supposed to be much greater than the magnetic field penetration depth. In this limiting case the problem is reduced

K. Shizuya

A field-theoretic formulation of a planar Hall-electron system with edges is presented and some fundamental aspects of the integer quantum Hall effect are studied with emphasis on clarifying general symmetry-based consequences of localization. It is shown, in particular, that the immobility of localized electron states and current compensation by extended el

N. Rajewsky, L. Santen, A. Schadschneider, M. Schreckenberg

The asymmetric exclusion process (ASEP) has attracted a lot of interest not only because its many applications, e.g. in the context of the kinetics of biopolymerization and traffic flow theory, but also because it is a paradigmatic model for nonequilibrium systems. Here we study the ASEP for different types of updates, namely random-sequential, sequential, s

Janyce Wiebe, Rebecca Bruce, Lei Duan

This paper describes the automation of a new text categorization task. The categories assigned in this task are more syntactically, semantically, and contextually complex than those typically assigned by fully automatic systems that process unseen test data. Our system for assigning these categories is a probabilistic classifier, developed with a recent meth

Nita Parekh, V. Ravi Kumar, B. D. Kulkarni

In this paper we show that the analysis of the dynamics in localized regions, i.e., sub-systems can be used to characterize the chaotic dynamics and the synchronization ability of the spatiotemporal systems. Using noisy scalar time-series data for driving along with simultaneous self-adaptation of the control parameter representative control goals like suppr

Martin Sieber

We derive semiclassical contributions of periodic orbits from a boundary integral equation for three-dimensional billiard systems. We use an iterative method that keeps track of the composition of the stability matrix and the Maslov index as an orbit is traversed. Results are given for isolated periodic orbits and rotationally invariant families of periodic

G. Sonneborn, C. S. J. Pun, R. A. Kimble, T. R. Gull

Visual and ultraviolet spatially resolved (~ 0."1) spectra of SN 1987A obtained on days 3715 and 3743 with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope show that the high-velocity SN debris is colliding with circumstellar gas. Very broad Ly-alpha emission with velocities extending to ~ +/- 20,000 km/s originates inside the inner

R. F. Anderson, Thomas S. Statler

The stellar velocity fields of elliptical galaxies hold clues to their dynamical structure and origin. The construction of velocity field models is greatly simplified by assuming an approximate geometrical form for the streamlines of the mean stellar motions. We test the conjecture that confocal streamlines are a valid approximation for realistic triaxial sy

Mark J. McCaughrean, Hua Chen, John Bally, Ed Erickson

We present the first high-resolution near-infrared images of the edge-on silhouette circumstellar disk, Orion 114-426, made using NICMOS on the Hubble Space Telescope. Images taken against the bright nebular background of the ionized hydrogen Pa$α$ line at 1.87 micron show the major axis of the disk to be approximately 20% smaller than at 0.6 micron, from wh

Limin Lu, Wallace L. W. Sargent, Thomas A. Barlow

Recent abundance measurements in damped Lyman-alpha galaxies, supplemented with unpublished Keck observations, are discussed. The metallicity distribution with cosmic time is examined for clues about the degree of enrichment, the onset of initial star formation, and the nature of the galxies. The relative abundances of the elements are compared with the abun

Philippe Fischer, Carlton Pryor, Stephen Murray, Mario Mateo

We have carried out WFPC2 V- and I-band imaging of the young LMC cluster NGC 2157. Construction of a color-magnitude diagram and isochrone fitting yields an age of tau = 100 000 000 yrs, a reddening E(B-V) = 0.1 and a distance modulus of 18.4 mag. Our data covers the mass range 0.75 < m < 5.1 solar masses. We find that the cluster mass function changes signi

V. Springel, S. D. M. White, J. M. Colberg, H. M. P. Couchman

We study the topology of the Virgo N-body simulations and compare it to the 1.2-Jy redshift survey of IRAS galaxies by means of the genus statistic. Four high-resolution simulations of variants of the CDM cosmology are considered: a flat standard model (SCDM), a variant of it with more large-scale power (tCDM), and two low density universes, one open (OCDM)

J. Jimenez-Vicente, C. Porcel, M. L. Sanchez-Saavedra, E. Battaner

We propose new parameters to describe the geometry of a warped disc when viewed edge-on, a global warp parameter $w$, and a family of three parameters $A$, $B$ and $C$ that describe, independently, the shape of the warp. These parameters are useful to detect some key effects in the understanding of warps. We have also developed software (WIG) which is able t

D. Lazzati, S. Campana, P. Rosati, G. Chincarini

We present a refinement of the wavelet analysis technique for the detection and characterisation of small scale features embedded in a strongly varying background. This technique handles with particular care the side effects of non-orthogonality in the wavelet space which can cause spurious detections and lead to a biased estimate of source parameters. This

A. Udalski, M. Szymanski, M. Kubiak, G. Pietrzynski

We present photometric observations of the MACHO-SMC-1 microlensing candidate collected by the OGLE-2 project. We show light curves of both components of the 1.6 arcsec blend: microlensed star and its optical companion. We find the contribution of the optical companion to the total flux to be 24% and confirm presence of the small amplitude periodic oscillati

R. Benton Metcalf, Joseph Silk

It has been argued that the power spectrum of the anisotropies in the Cosmic Microwave Background (CMB) may be effectively degenerate, namely that the observable spectrum does not determine a unique set of cosmological parameters. We describe the physical origin of this degeneracy and show that at small angular scales it is broken by gravitational lensing: e

Alan Owens, A. N. Parmar, T. Oosterbroek, A. Orr

We report the discovery of X-ray emission from comet C/1995 O1 (Hale-Bopp) by the LECS instrument on-board BeppoSAX on 1996 September 10--11. The 0.1--2.0 keV luminosity decayed by a factor of 2 on a timescale of ~10 hr with a mean value of 5.10E16 erg s-1. The spectrum is well fit by a thermal bremsstrahlung model with a temperature of 0.29 +/- 0.06 keV, or

R. Capuzzo-Dolcetta, P. Miocchi

The decay of globular clusters to the center of their mother galaxy corresponds to carrying a quantity of mass sufficient to sustain the gravitational activity of a small pre-existing nucleus and to accrete it in a significant way. This is due to both dynamical friction of field stars and tidal disruption by the compact nucleus. The results of the simplified

Ortwin Gerhard, James Binney, HongSheng Zhao

We summarize recent work on the structure and dynamics of the Galactic bar and inner disk. Current work focusses on constructing a quantitative model which integrates NIR photometry, source count observations, gas kinematics, stellar dynamical observations, and microlensing. Some avenues for future research are discussed.

Megan Govender, Sunil Maharaj, Roy Maartens

We find a simple exact model of radiating stellar collapse, with a shear-free and non-accelerating interior matched to a Vaidya exterior. The heat flux is subject to causal thermodynamics, leading to self-consistent determination of the temperature $T$. We solve for $T$ exactly when the mean collision time $τ_{c}$ is constant, and perturbatively in a more re

C. M. Sykes, I. W. A. Browne, N. J. Jackson, D. R. Marlow

We report the discovery of the most complex arcsec-scale radio gravitational lens system yet known. B1933+503 was found during the course of the CLASS survey and MERLIN and VLA radio maps reveal up to 10 components. Four of these are compact and have flat spectra; the rest are more extended and have steep spectra. The background lensed object appears to cons

N. Masetti, C. Bartolini, A. Guarnieri, A. Piccioni

B, V and R optical photometry performed on the field of the GRB 970111 soon after its detection by BeppoSAX is presented. No remarkable optical object is found inside the corrected error box. The optical counterpart of an X-ray and radio source and a suspected red variable (probably an eclipsing binary) have been detected inside the field of GRB 970111.

S. Gluzman, V. I. Yukalov

The self-similar analysis of time series, suggested earlier by the authors, is applied to the description of market crises. The main attention is payed to the October 1929, 1987 and 1997 stock market crises, which can be successfully treated by the suggested approach. The analogy between market crashes and critical phenomena is emphasized.

Barry R. Holstein

Compton scattering offers in principle an intriguing new window on nucleon structure. Existing experiments and future programs are discussed and the state of theoretical understanding of such measurements is explored.

M. R. Garcia, P. J. Callanan, D. Moraru, J. E. McClintock

We report on R_c and K band observations of the optical counterpart to GRB 970508 with the Fred Lawrence Whipple Observatory (FLWO) 1.2m telescope. Eleven R_c-band observations were obtained on 1997 May 12, and three on May14. The counterpart clearly faded between the two nights. On May 12 there was no evidence for variability (<9%) on 10-70 minute time scal

J. Gaite

The relative entropy in two-dimensional Field Theory is studied for its application as an irreversible quantity under the Renormalization Group, relying on a general monotonicity theorem for that quantity previously established. In the cylinder geometry, interpreted as finite-temperature field theory, one can define from the relative entropy a monotonic quan

Christoph Adam, Gerardo L. Rossini

We compute the Schwinger terms in the energy-momentum tensor commutator algebra from the anomalies present in Weyl-invariant and diffeomorphism-invariant effective actions for two dimensional massless scalar fields in a gravitational background. We find that the Schwinger terms are not sensitive to the regularization procedure and that they are independent o

F. de Campos, O. J. P. Eboli, M. A. Garcia-Jareno, J. W. F. Valle

We study chargino pair production at LEP II in supersymmetric models with spontaneously broken R-parity. We perform signal and background analyses, showing that a large region of the parameter space of these models can be probed through chargino searches at LEP II. In particular, we determine the attainable limits on the chargino mass as a function of the ma

Andree Blotz, Edward Shuryak

Recent data on B decays involving $η&#39;$ may be explained if the singlet axial current of charmed quarks has large matrix element to $η&#39;$, and instantons were shown to be able to generate this effect. We study the magnitude of charm contributions to nucleon polarized structure functions generated in a similar way. Comparing the charm contribution, whic

I. V. Vancea

It has been recently shown that the eigenvalues of the Dirac operator can be considered as dynamical variables of Euclidean gravity. The purpose of this paper is to explore the possiblity that the eigenvalues of the Dirac operator might play the same role in the case of supergravity. It is shown that for this purpose some primary constraints on covariant pha

Edmond Iancu

For a high temperature non-Abelian plasma, we reformulate the hard thermal loop approximation as an effective classical thermal field theory for the soft modes. The effective theory is written in local Hamiltonian form, and the thermal partition function is explicitly constructed. It involves an ultraviolet cutoff which separates between hard and soft degree

Wei Cui, S. N. Zhang, Wan Chen

In the context of black hole spin in X-ray binaries, we propose that certain type of quasi-period oscillations (QPOs) observed in the light curves of black hole binaries (BHBs) are produced by X-ray modulation at the precession frequency of accretion disks, due to relativistic dragging of inertial frames around spinning black holes. These QPOs tend to be rel

E. A. Ivanov, B. M. Zupnik

We study peculiarities of realization of N=2 supersymmetry in N=2 abelian gauge theory with two sorts of FI terms, electric and magnetic ones, within manifestly supersymmetric formulations via the Mezincescu and harmonic-analytic prepotentials. We obtain a `magnetic&#39;, duality- transformed superfield form of the N=2 Maxwell effective holomorphic action wi

G. Fasano, M. Filippi, F. Bertola

The detailed surface photometry of a sample of early-type galaxies in the Hubble Deep Field is presented as part of a long-term project aimed to settle strong observational constraints to the theories modelling the evolution of elliptical galaxies from the early stages. The sample has been extracted, in the V_606 band, from the catalog by Couch (1996). The a

K. Zarembo

The properties of the ground state wavefunctional in gluodynamics responsible for confinement are considered. It is shown that confinement arises due to the generation of a mass gap in the averaging over the gauge group which is necessary to ensure the gauge invariance of the ground state. The string tension is calculated in assumption of a particular infrar

E. L. Gubankova, F. Wegner

The method of flow equations is applied to QED on the light front. Requiring that the partical number conserving terms in the Hamiltonian are considered to be diagonal and the other terms off-diagonal an effective Hamiltonian is obtained which reduces the positronium problem to a two-particle problem, since the particle number violating contributions are eli

A. Y. Potekhin

Analytical approximations are constructed for binding energies, quantum-mechanical sizes and oscillator strengths of main radiative transitions of hydrogen atoms arbitrarily moving in magnetic fields 10^{12}-10^{13} G. Examples of using the obtained approximations for determination of maximum transverse velocity of an atom and for evaluation of absorption sp

K. Kajantie, M. Laine, K. Rummukainen, M. Shaposhnikov

The effective super-renormalizable 3-dimensional Lagrangian, describing the high temperature limit of chiral gauge theories, has more symmetry than the original 4d Lagrangian: parity violation is absent. Parity violation appears in the 3d theory only through higher-dimensional operators. We compute the coefficients of dominant P-odd operators in the Standard

Ruben Minasian, Gregory Moore

We discuss the relation between the Ramond-Ramond charges of D-branes and the topology of Chan-Paton vector bundles. We show that a topologically nontrivial normal bundle induces RR charge and that the result fits in perfectly with the proposal that D-brane charge is the topology of the Chan-Paton bundle, regarded as an element of K-theory.

S. P. de Alwis

The scaling limit used recently to derive matrix models, and a certain analyticity assumption, are invoked to argue that the agreement between some matrix model calculations and supergravity is a consequence of string world sheet duality.

A. G. Izergin, V. S. Kapitonov, N. A. Kitanine

Representations as determinants of $M\times M$ dimensional matrices are obtained for equal-time temperature correlators of the anisotropic Heisenberg XY chain. These representations are simple deformations of the answers for the isotropic XX0 chain. In the thermodynamic limit, the correlators are expressed in terms of the Fredholm determinants of linear inte

Hans-Thomas Elze

Entropy generation in quantum sytems is tied to the existence of a nonclassical environment (heat bath or other) with which the system interacts. The continuous `measuring&#39; of the open system by its environment induces decoherence of its wave function and entropy increase. Examples of nonrelativistic quantum Brownian motion and of interacting scalar fiel

Hans R. Griem, Yuri V. Ralchenko, Igor Bray

We present a quantum-mechanical calculation of Stark line widths from electron-ion collisions for the $2s_{1/2}-2p_{1/2,3/2}$, lambda = 2066 and 2067 A, resonance transitions in B III. The results confirm the previous quantum-mechanical R-matrix calculations but contradict recent measurements and semi-classical and some semi-empirical calculations. The diffe

G. G. Ryzhikh, J. Mitroy

Calculations of the positron-Li system were performed using the Stochastic Variational Method and yielded a minimum energy of -7.53208 Hartree for the L=0 ground state. Unlike previous calculations of this system, the system was found to be stable against dissociation into the Ps + Li$^+$ channel with a binding energy of 0.00217 Hartree and is therefore elec

M. I. Krivoruchenko

The unitarity relations for isovector nucleon form factors in the two-pion approximation for the intermediate states are analytically extended in a model independent way from the real half-axis t > 4 $μ^2$ ($μ$ is the pion mass) to the whole complex t-plane. As a result, the explicit integral representations for the nucleon form factors are constructed in te

Ye. S. Golubeva, L. A. Kondratyuk, W. Cassing

The $ω$-, $ρ$- and $ϕ$-resonance production and their dileptonic decay in $π^- A$ reactions at 1.1 - 1.7 GeV/c are calculated within the intranuclear cascade (INC) approach. The invariant mass distribution of the dilepton pair for each resonance can be decomposed in two components which correspond to their decay &#39;inside&#39; the target nucleus and in the

Vatche Sahakian

We investigate excitations in Matrix Theory on T^2 corresponding to bound states of strings. We demonstrate the Dirichlet aspect of R-R charged vacua through a non-trivial connection between the U(1) and SU(n) sectors of the matrix SYM.