December 1997 arXiv papers

Charanjit S. Aulakh, Alejandra Melfo, Andrija Rasin, Goran Senjanovic

We show that the low energy limit of the minimal supersymmetric Left-Right models is the supersymmetric standard model with an exact R-parity. The theory predicts a number of light Higgs scalars and fermions with masses much below the $B-L$ and $SU(2)_R$ breaking scales. The non-renormalizable version of the theory has a striking prediction of light doubly c

Luis Gonzalez-Mestres

Although Lorentz symmetry has been tested at low energy with extremely good accuracy, its validity at very high energy is much less well established. If Lorentz symmetry violation (LSV) is energy-dependent (e.g. $\propto E^2$), it can be of order 1 at Planck scale and undetectable at GeV scale or below. Similarly, superluminal particles with positive mass an

J. Teschner

A closed formula for the structure constants in the SL(2,C)/SU(2) WZNW model is derived by a method previously used in Liouville theory. With the help of a reflection amplitude that follows from the structure constants one obtains a proposal for the fusion rules from canonical quantization. Taken together these pieces of information allow an unambigous defin

J. Teschner

Many qualitatively new features of WZNW models associated to noncompact cosets are due to zero modes with continuous spectrum. Insight may be gained by reducing the theory to its zero-mode sector, the mini-superspace limit. This will be discussed in some detail for the example of SL(2,C)/SU(2)-WZNW model. The mini-superspace limit of this model can be formul

J. Fuchs, C. Schweigert

Motivated by recent developments in string theory, we study the structure of boundary conditions in arbitrary conformal field theories. A boundary condition is specified by two types of data: first, a consistent collection of reflection coefficients for bulk fields on the disk; and second, a choice of an automorphism $ω$ of the fusion rules that preserves co

D. M. Wei, T. Lu

The detection of delayed X-ray, optical and radio emission, "afterglow", associated with $γ$-ray bursts (GRBs) is consistent with fireball models, where the emission are produced by relativistic expanding blast wave, driven by expanding fireball at cosmogical distances. The emission mechanisms of GRB afterglow have been discussed by many authors and

L. Clavelli, P. W. Coulter, Levan R. Surguladze

Depending on their masses, Supersymmetric particles can affect various measurements in Z decay. Among these are the total width (or consequent extracted value of $α_s$), enhancement or suppression of various flavors, and left-right and forward-backward asymmetries. The latter depend on squark mass splittings and are, therefore, a possible test of the Supergr

J. Blümlein, A. Vogt

A systematic study is performed of the impact of the various resummed small-$x$ contributions to the anomalous dimensions and coefficient functions on the evolution of unpolarized structure functions in deep-inelastic scattering. The proton structure functions $F_2^p$ and $F_L^p$ as well as the photon structure function $F_2^γ$ are considered together with t

Nobuhiko Shinzawa, Satoru Saito

The Hirota bilinear difference equation is generalized to discrete space of arbitrary dimension. Solutions to the nonlinear difference equations can be obtained via Bäcklund transformation of the corresponding linear problems.

Igor V. Kanatchikov

Elements of the quantization in field theory based on the covariant polymomentum Hamiltonian formalism (the De Donder-Weyl theory), a possibility of which was originally discussed in 1934 by Born and Weyl, are developed. The approach is based on a recently proposed graded Poisson bracket on differential forms in field theory (see e.g. hep-th/9709229). A cova

Alexander V. Bogdanov, Ashot S. Gevorkyan

The new perturbation theory for the problem of nonstationary anharmonic oscillator with polynomial nonstationary perturbation is proposed. As a zero order approximation the exact wave function of harmonic oscillator with variable frequency in external field is used. Based on some intrinsic properties of unperturbed wave function the variational-iterational m

Zhirair S. Gevorkian

Radiation of relativistic charged particles in a system of randomly spaced plates is considered in the paper. It is shown that for large number of plates ($N \gg 1$), in the wavelength range $λ\ll l\ll L$ (where $l$ is the photon mean free path and $L$ is the system characteristic size) and for angles $|\cos θ|\gg (λ/2πl)^{1/3}$, pseudophoton diffusion repre

Eric G. Blackman

The importance of a teaching a clear definition of the ``observer'' in special relativity is highlighted using a simple astrophysical example from the exciting current research area of ``Gamma-Ray Burst'' astrophysics. The example shows that a source moving relativistically toward a single observer at rest exhibits a time ``contraction'&#

Masato Hisakado

The soliton structure of a gauge theory proposed to describe chiral excitations in the multi-Layer Fractional Quantum Hall Effect is investigated. A new type of derivative multi-component nonlinear Schrödinger equation emerges as effective description of the system that supports novel chiral solitons. We discuss the classical properties of the solutions and

Jan Kalinowski

In R-parity violating SUSY models sleptons can be produced singly in e+e- and qqbar collisions. The formation of slepton resonances at LEP2 or Tevatron at current energies is an exciting possibility. Existing LEP2 and Tevatron data can be exploited to look for sleptons and, if unsuccessful, to derive bounds on the Yukawa couplings of sleptons to quark and le

A. G. Zubkov, O. V. Dubasov, B. O. Kerbikov

A straightforward algebraic derivation is carried out of light quark propagator and effective action in the instanton-anti-instanton molecule. Exact expressions are obtained which contain contributions of all quark modes. Possible implications of the results include chiral phase transition and correlation functions of mesons and baryons.

G. G. Raffelt

Recent developments of those areas of astro-particle physics are discussed that were represented at the HEP97 conference. In particular, the current status of direct and indirect dark-matter searches and of TeV neutrino and gamma-ray astronomy will be reviewed.

Frank Würthwein, Peter Gaidarev

It has previously been shown that a measurement of Arg$(V_{ub})=γ$ can be obtained from a triangle construction using ${\cal B}(B^0\to K^+π^-)$, ${\cal B}(\bar{B^0}\to K^-π^+)$, ${\cal B}(B^\pm\to K^0_sπ^\pm)$, and ${\cal B}(B^\pm\to π^\pmπ^0)$. We evaluate experimental as well as theoretical uncertainties in this measurement. We find that a measurement of $

S. S. Xulu

Virbhadra and Parikh studied the energy distribution associated with stringy charged black hole in Einstein's prescription. We study the same using Tolman's energy-momentum complex and get the same result as obtained by Virbhadra and Parikh. The entire energy is confined inside the black hole.

A. G. Galstyan, M. E. Raikh

We study theoretically the disorder-induced smearing of the density of states in a two-dimensional electron system taking into account a spin-orbit term in the Hamiltonian of a free electron. We show that the characteristic energy scale for the smearing increases with increasing the spin-orbit coupling. We also demonstrate that in the limit of a strong spin-

J. I. Katz

In order to explain the positive temperature coefficient of the visible index of refraction of fused silica I develop a simple model which assumes a single ultraviolet resonance. Assuming thermal broadening and using the Kramers- Kronig relations leads to a temperature coefficient in qualitative, but not quantitative, agreement with measurement.

H. A. Mook, P. Dai, R. D. Hunt, F. Dogan

Neutron scattering measurements have been made on the spin fluctuations in YBa_2Cu_3O_{7-δ} for different oxygen doping levels. Incommensurability is clearly observed for oxygen concentrations of 6.6 and 6.7 and is suggested for the 6.93. Measurements of the resonance for the O_{6.6} concentration show that it exists in a broadened and less intense form at t

P. Strehlow, C. Enss, S. Hunklinger

Dielectric measurements at very low temperature indicate that in a glass with the eutectic composition BaO-Al$_2$O$_3$-SiO$_2$ a phase transition occurs at 5.84 mK. Below that temperature small magnetic fields of the order of 10 $μ$T cause noticeable changes of the dielectric constant although the glass is insensitive to fields up to 20 T above 10 mK. The ex

P. Farkasovsky

The phase diagram of the Hubbard model in an external magnetic field is examined by extrapolation of small-cluster exact-diagonalization calculations. Using a general expression for the hopping matrix elements ($t_{ij}\sim q^{|i-j|}$) the influence of long-range hopping (band asymmetry) on ferromagnetism in this model is studied. It is found that the long-ra

S. De Bièvre, G. Forni

We study transport properties of Schrödinger operators depending on one or more parameters. Examples include the kicked rotor and operators with quasi-periodic potentials. We show that the mean growth exponent of the kinetic energy in the kicked rotor and of the mean square displacement in quasi-periodic potentials is generically equal to 2: this means that

Lars Bildsten, Andrew Cumming, Greg Ushomirsky, Curt Cutler

Observations of quasi-periodic oscillations (QPOs) in the luminosity from many accreting neutron stars (NS) have led us to investigate a source of periodicity prevalent in other stars: non-radial oscillations. After summarizing the structure of the atmosphere and ocean of an accreting NS, we discuss the various low l g-modes with frequencies in the 1-100 Hz

Jonathan E. Grindlay

Several payloads for hard X-ray (20-600 keV) imaging with coded aperture telescopes have been developed for balloon flight observations of cosmic x-ray sources. We briefly review the characteristics of these, particularly the EXITE2 system. The recent NASA program to develop an extended long duration (100d) balloon flight capability employing super-pressure

Kenneth S. K. Lum, Joseph J. Mohr, Didier Barret, Jonathan E. Grindlay

We have modelled the hard X-ray background expected for a high-altitude balloon flight of the Energetic X-ray Telescope Experiment (EXITE2), an imaging phoswich detector/telescope for the 20--600 keV energy range. Photon and neutron-induced contributions to the background are considered. We describe the code and the results of a series of simulations with di

Theodore R. Gull, Don J. Lindler, D. Michael Crenshaw, Joseph F. Dolan

We present the spectrum and pulse profile of the Crab Pulsar in the near ultraviolet (1600-3200 Angstroms) observed with the Space Telescope Imaging Spectrograph (STIS) during the Hubble Space Telescope (HST) second Servicing Mission Orbital Verification (SMOV) period. The two-dimensional Near-Ultraviolet Multi-Anode Microchannel Array (NUV MAMA) was used in

Bruce G. Elmegreen

The progressive mixing and contamination of interstellar gas by supernovae and other processes following the passage of a spiral density wave is reviewed, with an emphasis on the Solar neighborhood. Regions of star formation should begin their lives with an inhomogeneous mixture of abundances as a result of their chaotic and large-scale formation processes.

Deidre A. Hunter, Bruce G. Elmegreen, Aomawa L. Baker

We explore various instability models for the onset of star formation in irregular galaxies. Critical gas densities are calculated for gravitational instabilities with a thin, pure-gas disk, and with a thick disk composed of gas and a star-like fluid. We also calculated the stability properties of three dimensional systems including dark matter, considered t

B. G. Elmegreen

Star formation triggering mechanisms are reviewed, including the direct compression of clouds and globules, the compression and collapse of molecular clouds at the edges of HII regions and supernovae, the expansion and collapse of giant rings and shells in galaxy disks, and the collision and collapse between two clouds. Collapse criteria are given. A compreh

D. M. Wei, T. Lu

The detection of the delayed emission in X-ray, optical and radio band, i.e. the afterglow of $γ$-ray bursts (GRBs), suggestes that the sources of GRBs are likely to be at cosmological distances. Here we explore the interaction of a relativistic shell with a uniform interstellar medium (ISM) and obtain the exact solution of the evolution of $γ$-ray burst rem

Brad K. Gibson

Several speakers at IAU Symposium #187 (Cosmic Chemical Evolution) alluded to the zeroth-order agreement between Type II supernovae (SNe) stellar yield compilations, as predicted by the models of those most responsible for driving progress in the field - i.e., Arnett (1991,1996); Maeder (1992); Woosley & Weaver (1995); Langer & Henkel (1995); Thielemann et a

Nguyen Quoc Thang

We prove some new relations between weak approximation and some rational equivalence relations (Brauer and R-equivalence) in algebraic groups over arithmetical fields. By using weak approximation and local - global approach, we compute completely the group of Brauer equivalence classes of connected linear algebraic groups over number fields, and also complet

Vipul Periwal

Finite sample size corrections to the reparametrization-invariant solution of the inverse problem of probability are computed, and shown to converge uniformly to the correct distribution.

Andrew Strominger

Black holes whose near-horizon geometries are locally, but not necessarily globally, AdS$_3$ (three-dimensional anti-de Sitter space) are considered. Using the fact that quantum gravity on AdS$_3$ is a conformal field theory, we microscopically compute the black hole entropy from the asymptotic growth of states. Precise numerical agreement with the Bekenstei

N. I. Kulikov, A. V. Postnikov, G. Borstel, J. Braun

Ab initio calculation results for the electronic structure of disordered bcc Fe(x)Al(1-x) (0.4<x<0.75), Co(x)Al(1-x) and Ni(x)Al(1-x) (x=0.4; 0.5; 0.6) alloys near the 1:1 stoichiometry, as well as of the ordered B2 (FeAl, CoAl, NiAl) phases with point defects are presented. The calculations were performed using the coherent potential approximation within th

M. A. Baranov, A. M. M. Pruisken, B. Skoric

The concept of F-invariance, which previously arose in our analysis of the integral and half-integral quantum Hall effects, is studied in 2+2εspatial dimensions. We report the results of a detailed renormalization group analysis and establish the renormalizability of the (Finkelstein) action to two loop order. We show that the infrared behavior of the theory

Amanda W. Peet

A review of recent progress in string theory concerning the Bekenstein formula for black hole entropy is given. Topics discussed include p-branes, D-branes and supersymmetry; the correspondence principle; the D- and M-brane approach to black hole entropy; the D-brane analogue of Hawking radiation, and information loss; D-branes as probes of black holes; and

S. Ya. Kotkovsky, I. M. Narodetskii, S. Simula, K. A. Ter-Martirosyan

A relativistic constituent quark model, formulated on the light-front, is used to derive a new parton approximation for the inclusive semileptonic decay width of the B-meson. A simple connection between the decay rate of a free heavy-quark and the one of a heavy-quark bound in a meson or in a baryon is established. The main features of the new approach are t

Viacheslav V. Nikulin

Here we prove classification results announced in Part I (alg-geom/9711032). We classify maximal hyperbolic root systems of the rank 3 having restricted arithmetic type and a generalized lattice Weyl vector $ρ$ with $ρ^2\ge 0$ (i.e. of elliptic or parabolic type). We give classification of all reflective of elliptic or parabolic type elementary hyperbolic la

Rama Cont, Jean-Philippe Bouchaud

We present a simple model of a stock market where a random communication structure between agents gives rise to a heavy tails in the distribution of stock price variations in the form of an exponentially truncated power-law, similar to distributions observed in recent empirical studies of high frequency market data. Our model provides a link between two well

P. Mitra

In this note it is shown that near-extremal four dimensional dyonic black holes, where the dilaton is not constant, can be described by a microscopic model consisting of a one-dimensional gas of massless particles.

Henk Eskes, Osman Yousif Osman, Rob Grimberg, Wim van Saarloos

A generic lattice cut-off model is introduced describing the quantum meandering of a single cuprate stripe. The fixed point dynamics is derived, showing besides free string behavior a variety of partially quantum disordered phases, bearing relationships both with quantum spin-chains and surface statistical physics.

Borge Nodland

We propose that spacetime is fundamentally a property of matter, inseparable from it. This leads us to suggest that all properties of matter must be elevated to the same status as that of spacetime in quantum field theories of matter. We suggest a specific method for extending field theories to accomodate this, and point out how this leads to the evolution o

J. S. Milne

We verify that the descent maps provided by Langlands&#39;s Conjugacy Conjecture do satisfy the continuity condition necessary for them to be effective. Thus Langlands&#39;s conjecture does imply the existence of canonical models. This replaces an earlier version of the paper --- the proof in this version is simpler, and the exposition more detailed.

Sang Koo You, Kwang Joe Jeon, Chul Koo Kim, Kyun Nahm

An approximation method which combines the perturbation theory with the variational calculation is constructed for quantum mechanical problems. Using the anharmonic oscillator and the He atom as examples, we show that the present method provides an efficient scheme in estimating both the ground and the excited states. We also discuss the limitations of the p

C. I. Lazaroiu

Motivated by the study of heterotic string compactifications on elliptically fibered Calabi-Yau manifolds, we present a procedure for testing semistability and identifying the decomposition type of degree zero holomorphic vector bundles over a nonsingular elliptic curve. The algorithm requires explicit knowledge of a basis of sections of an associated `twist

O. M. Khudaverdian, D. A. Sahakyan

For a given configuration space $M$ and Lie algebra $g$ whose action is defined on $M$, the space $V_{0.0}$ of weakly $g$-invariant Lagrangians (i.e. Lagrangians whose motion equations left hand sides are $g$-invariant) is studied. The problem is reformulated in the terms of the double complex of Lie algebra cochains with values in the complex of Lagrangians

Andrei V. Afanasev, V. D. Afanasev, S. V. Trubnikov

Relativistic integral representation in terms of experimental neutron-proton scattering phase shifts alone is used to compute the charge form factor of the deuteron $G_{Cd}(Q^2)$. The results of numerical calculations of $|G_{Cd}(Q^2)|$ are presented in the interval of the four-momentum transfers squared $0 \leq Q^2 \leq 35 fm^{-2}$. Zero and the prominent s

A. Fabrocini, F. Arias de Saavedra, G. Co&#39;, P. Folgarait

The ground state properties of N=Z doubly closed shell nuclei are studied within correlated basis function theory. A truncated version of the Urbana v14 realistic potential, with spin, isospin and tensor components, is adopted, together with state dependent correlations. Fermi hypernetted chain integral equation and single operator chain approximation are us

Yong-Zhong Qian

All of the actinides and roughly half the natural abundance of elements with mass number A > 70 come from the rapid neutron capture process, or the r-process. If the r-process, as suggested by many, occurs deep in a supernova, then it is under the influence of an intense neutrino flux. Here we discuss the effects of both charged-current and neutral-current n

Ki-Bong Nam

It is well known that the Poisson Lie algebra is isomorphic to the Hamiltonian Lie algebra. We show that the Poisson Lie algebra can be embedded properly in the special type Lie algebra. We also generalize the Hamiltonian Lie algebra using exponential functions, and we show that these Lie algebras are simple.

Ki-Bong Nam

We introduce a new class of simple Lie algebras $W(n,m)$ that generalize the Witt algebra by using &#34;exponential&#34; functions, and also a subalgebra $W^*(n,m)$ thereof; and we show each derivation of $W^*(1,0)$ can be written as a sum of an inner derivation and a scalar derivation. The Lie algebra $W(n,m)$ is $Z$-graded and is infinite growth.

Boris Apanasov

This paper concerns with deformations of noncompact complex hyperbolic manifolds (with locally Bergman metric), varieties of discrete representations of their fundamental groups into $PU(n,1)$ and the problem of (quasiconformal) stability of deformations of such groups and manifolds in the sense of L.Bers and D.Sullivan. Despite Goldman-Millson-Yue rigidity

Joel Hass

This is a survey paper on algorithms for solving problems in 3-dimensional topology. In particular, it discusses Haken&#39;s approach to the recognition of the unknot, and recent variations.

William P. Thurston

This paper investigates certain foliations of three-manifolds that are hybrids of fibrations over the circle with foliated circle bundles over surfaces: a 3-manifold slithers around the circle when its universal cover fibers over the circle so that deck transformations are bundle automorphisms. Examples include hyperbolic 3-manifolds of every possible homolo

Frederick M. Goodman, Sergei V. Kerov

We find the Martin boundary for the Young-Fibonacci lattice YF. Along with the lattice of Young diagrams, this is the most interesting example of a differential poset. The Martin boundary construction provides an explicit Poisson-type integral representation of non-negative harmonic functions on YF. The latter are in a canonical correspondence with a set of

D. Bernard, B. Julia

The Geroch group, isomorphic to the SL(2,R) affine Kac-Moody group, is an infinite dimensional solution generating group of Einstein&#39;s equations with two surface orthogonal commuting Killing vectors. We introduce another solution generating group for these equations, the dressing group, and discuss its connection with the Geroch group. We show that it ac

A. E. Faraggi, M. Matone

The content of the comment [hep-th/9712219] is the derivation of Eq.(13) in Phys. Rev. Lett. 78 (1997) 163 by direct differential calculus: which is precisely the same method we used to derive it (it is in fact difficult to imagine any other possible derivation).

Stephen Godfrey

I review the properties of mesons with one heavy quark. I start by examining the predicted masses and widths in the context of the quark model and heavy quark effective theory. Some recent experimental results are described and I conclude with comments on potentially interesting future experimental studies.

Stephen Godfrey

I give a brief introduction to light $q\bar{q}$ resonances. The properties of $q\bar{q}$ states are discussed in the context of the constituent quark model, including predictions for mass and partial decay widths. Problems and puzzles in the meson spectrum are pointed out with an emphasis on how an 8+ GeV photon beam can address these. I also point out some

I. Jack, D. R. T. Jones, A. Pickering

We demonstrate that the soft supersymmetry-breaking terms in a N=1 theory can be linked by simple renormalisation group invariant relations which are valid to all orders of perturbation theory. In the special case of finite N=1 theories, the soft terms preserve finiteness to all orders.

David Tung, Hsiang-nan Li

We recalculate the pion electromagnetic form factor based on the perturbative QCD formalism that includes the Sudakov resummation. We take into account the evolution of the pion wave function in $b$, which represents the transverse extent of the pion. An infrared enhancement is observed when $1/b$ approaches $Λ_{QCD}$. We propose to freeze the evolution of t

Thomas Friedrich

The aim of the present paper is to clarify the relationship between immersions of surfaces and solutions of the inhomogeneous Dirac equation. The main idea leading to the description of a surface M^2 by a spinor field is the observation that the restriction to M^2 of any parallel spinor phi on R^3 is (with respect to the inner geometry of M^2) a non-trivial

Gang Liu, Gang Tian

In this paper, we establish a general relationship between the nonvanishing of GW invariants with the existence of the closed orbits of a Hamiltonian system. As an application, we completely solved the stabilized Weinstein conjecture.

George I. Kamberov

Global isothermic immersions are defined and studied with the aid of a connection between quadratic differentials and immersions. The applications are two problems stemming from the fundamental question: how much data is needed to identify a surface immersion (Christoffel&#39;s problem) or its shape (Bonnet&#39;s problem). A short complete solution of Christ

Bernd A. Berg, Wolfhard Janke

We introduce a novel method for numerical spin glass investigations: Simulations of two replica at fixed temperature, weighted such that a broad distribution of the Parisi overlap parameter $q$ is achieved. Canonical expectation values for the entire $q$-range (multi-overlap) follow by re-weighting. We demonstrate the feasibility of the approach by studying

Gilson Carneiro, Pascal Lederer

In doped two-leg spin ladder systems, holes are expected to form charged bosonic pairs. We study charge transport in this system in the temperature range where the bosons can be described as weakly interacting quasi-particles. We consider boson-phonon and boson-impurity scattering processes. We suggest that due to the Ioffe-Regel resistivity saturation mecha

F. Eghbal, D. Foster, H. Orland

An exact calculation of the phase diagram for a loop gas model on the brickwork lattice is presented. The model includes a bending energy. In the dense limit, where all the lattice sites are occupied, a phase transition occuring at an asymmetric Lifshitz tricritical point is observed as the temperature associated with the bending energy is varied. Various cr

N. Shibata, B. Ammon, M. Troyer, M. Sigrist

Thermodynamic properties of the one-dimensional Kondo lattice model at half-filling are studied by the density matrix renormalization group method applied to the quantum transfer matrix. Spin susceptibility, charge susceptibility, and specific heat are calculated down to T=0.1t for various exchange constants. The obtained results clearly show crossover behav

S. Lukyanov

Coupling constants for the most relevant terms in the low energy effective Hamiltonian of the XXZ spin chain are derived. Using this result we study the low energy (low temperature, weak magnetic field) thermodynamics, finite size effects and subleading long distance asymptotics of correlation functions.

Lev Titarchuk, Iosif Lapidus, Alex Muslimov

We explain the millisecond variability detected by Rossi X-ray Timing Explorer (RXTE) in the X-ray emission from a number of low mass X-ray binary systems (Sco X-1, 4U1728-34, 4U1608-522, 4U1636-536, 4U0614+091, 4U1735-44, 4U1820-30, GX5-1 and etc) in terms of dynamics of the centrifugal barrier, a hot boundary region surrounding a neutron star. We demonstra

Omer Blaes

Accretion disk models still do not provide a satisfactory explanation of the optical/ultraviolet continuum observed in Seyferts and quasars. Substantial theoretical progress has been made in understanding one aspect of the problem: the dearth of spectral features at the Lyman limit. Promising solutions have also been proposed to explain the surprising observ

Ali Nayeri

We have used a toy model to study the behaviour of confined binary systems in 2$D$ and compare it with previously known result in 3$D$. In the case of 2$D$, in which canonical distribution exists only above a critical temperature, we evaluate the exact form of partition function for this system and compare the exact partition function with the mean field par

A. Cillis, S. J. Sciutto

The influence of the geomagnetic field on the development of air showers is studied. The well known International Geomagnetic Reference Field was included in the AIRES air shower simulation program as an auxiliary tool to allow calculating very accurate estimations of the geomagnetic field given the geographic coordinates, altitude above sea level and date o

J. Richard Gott, III, Li-Xin Li

The question of first-cause has troubled philosophers and cosmologists alike. Now that it is apparent that our universe began in a Big Bang explosion, the question of what happened before the Big Bang arises. Inflation seems like a very promising answer, but as Borde and Vilenkin have shown, the inflationary state preceding the Big Bang must have had a begin

DS Akerib, PD Barnes, DA Bauer, PL Brink

We are conducting an experiment to search for WIMPs, or weakly-interacting massive particles, in the galactic halo using terrestrial detectors. This generic class of hypothetical particles, whose properties are similar to those predicted by extensions of the standard model of particle physics, could comprise the cold component of non-baryonic dark matter. We

Guenther Hasinger

ROSAT deep and shallow surveys have provided an almost complete inventory of the constituents of the soft X-ray background which led to a population synthesis model for the whole X-ray background with interesting cosmological consequences. According to this model the X-ray background is the ``echo&#39;&#39; of mass accretion onto supermassive black holes, in

Guenther Hasinger, Gianni Zamorani

In this article we review the measurements and understanding of the X-ray background (XRB), discovered by Giacconi and collaborators 35 years ago. We start from the early history and the debate whether the XRB is due to a single, homogeneous physical process or to the summed emission of discrete sources, which was finally settled by COBE and ROSAT. We then d

Victor V. Batyrev

For an arbitrary smooth n-dimensional Fano variety $X$ we introduce the notion of a small toric degeneration. Using small toric degenerations of Fano n-folds $X$, we propose a general method for constructing mirrors of Calabi-Yau complete intersections in $X$. Our mirror construction is based on a generalized monomial-divisor mirror correspondence which can

Andrzej Weber

Let $f:X-->Y$ be a map of algebraic varieties. Barthel, Brasselet, Fieseler, Gabber and Kaup have shown that there exists a homomorphism of intersection homology groups $f^*:IH^*(Y)-->IH^*(X)$ compatible with the induced homomorphism on cohomology. The crucial point in the argument is reduction to the finite characteristic. We give an alternative and short p

John M. Cornwall

We study adjoint and fundamental Wilson loops in the center-vortex picture of confinement, for gauge group SU(N) with general N. There are N-1 distinct vortices, whose properties, including collective coordinates and actions, we study. In d=2 we construct a center-vortex model by hand so that it has a smooth large-N limit of fundamental-representation Wilson

Erasmo Recami

In this paper we extend for the case of Maxwell equations the &#34;X-shaped&#34; solutions previously found in the case of scalar (e.g., acoustic) wave equations. Such solutions are localized in theory, i.e., diffraction-free and particle-like (wavelets), in that they maintain their shape as they propagate. In the electromagnetic case they are particularly i

F. Finelli, G. P. Vacca, G. Venturi

We study chaotic inflation driven by a real, massive, homogeneous minimally coupled scalar field in a flat Robertson-Walker spacetime. The semiclassical limit for gravity is considered, whereas the scalar field is treated quantum mechanically by the technique of invariants in order to also investigate the dynamics of the system for non-classical states of th

Muktish Acharyya

The nonequilibrium dynamic phase transition, in the kinetic Ising model in presence of an oscillating magnetic field, has been studied both by Monte Carlo simulation (in two dimension) and by solving the meanfield dynamical equation of motion for the average magnetization. The temperature variations of hysteretic loss (loop area) and the dynamic correlation

Till D. Kuehner, H. Monien

The zero-temperature phase diagram of the one-dimensional Bose-Hubbard model with nearest-neighbor interaction is investigated using the Density-Matrix Renormalization Group. Recently normal phases without long-range order have been conjectured between the charge density wave phase and the superfluid phase in one-dimensional bosonic systems without disorder.

C. B. Yang, X. Cai

Deviation of the multiplicity distribution $P_q$ in small bin from its Poisson counterpart $p_q$ is studied within the Ginzburg-Landau description for second-order quark-hadron phase transition. Dynamical factor $d_q\equiv P_q/p_q$ for the distribution and ratio $D_q\equiv d_q/d_1$ are defined, and novel scaling behaviors between $D_q$ are found which can be

A. V. Bratchikov

The conformal field theory based on the $g/u(1)^d$ coset construction is treated as the WZNW theory for the affine Lie algebra $\hat g$ with the constrained $\hat u(1)^d$ subalgebra.Using a modification of the generalized canonical quantization method generators and primary fields of an extended symmetry algebra are found for arbitrary d.

A. Samsonov, M. Schepkin

We comment on calculations of the width of the d&#39; resonance within framework of quark shell models.

H. Belich, G. Cuba, R. Paunov

We study the relation between the group-algebraic approach and the dressing symmetry one to the soliton solutions of the $A_n^{(1)}$ Toda field theory in 1+1 dimensions. Originally solitons in the affine Toda models has been found by Olive, Turok and Underwood. Single solitons are created by exponentials of elements which ad-diagonalize the principal Heisenb

S. Bellucci, A. Galajinsky

We examine the general conditions for the existence of the complex structure intrinsic in the Gupta-Bleuler quantization method for the specific case of mixed first and second class fermionic constraints in an arbitrary space-time dimension. The cases d=3 and 10 are shown to be of prime importance. The explicit solution for d=10 is presented.

Mikhail Vasiliev

We formulate a non-linear system of equations which describe higher-spin gauge interactions of massive matter fields in 2+1 dimensional space-time and explain some properties of the deformed oscillator algebra which underlies this formulation. In particular we show that the parameter of mass $M$ of matter fields is related to the deformation parameter in thi

M. Göckeler, R. Horsley, V. Linke, P. Rakow

We investigate a lattice version of QED by numerical simulations. For the renormalized charge and mass we find results which are consistent with the renormalized charge vanishing in the continuum limit. A detailed study of the relation between bare and renormalized quantities reveals that the Landau pole lies in a region of parameter space which is made inac

H. K. Jassal, A. Mukherjee, R. P. Saxena

The cosmological compactification of D=10, N=1 supergravity-super-Yang-Mills theory obtained from superstring theory is studied. The constraint of unbroken N=1 supersymmetry is imposed. A duality transformation is performed on the resulting consistency conditions. The original equations as well as the transformed equations are solved numerically to obtain ne

Boris Kayser

We review what has been learned about CP violation in the K system. It is natural to hypothesize that the observed CP-violating effects are caused by the Standard Model weak interaction. We describe the stringent future test of this hypothesis via experiments on the B system. Then, we see how new physics beyond the Standard Model could be revealed by this te

Vladimir Chekelian

Recent experimental results contributing to the understanding of the structure of the nucleon are reviewed. They include the final NMC results on proton and deuteron structure functions; a re-analysis of the CCFR data on F2 and xF3; new preliminary results from CDF on charge asymmetry in W production, from E866 on Drell-Yan mu-pair production and from E706 o

G. G. Raffelt

The physical nature of most of the gravitating mass in the universe is completely mysterious. The astrophysical evidence for the presence of this dark matter and astrophysical constraints on its properties will be reviewed. The most popular dark-matter candidates will be introduced, and current and future attempts to search for them directly and indirectly w

S. M. Bilenky, C. Giunti, W. Grimus

We discuss possibilities to investigate the effects of CP (and T) violation in the lepton sector in neutrino oscillation experiments. We consider the effects of CP violation in the framework of two schemes of mixing of four massive neutrinos that can accommodate the results of all neutrino oscillation experiments. Using the constraints on the mixing paramete