March 1999 arXiv papers — page 15

M. Montesinos, H. A. Morales-Tecotl, L. F. Urrutia, J. D. Vergara

A scalar field nonminimally coupled to gravity is studied in the canonical framework, using self-dual variables. The corresponding constraints are first class and polynomial. To identify the real sector of the theory, reality conditions are implemented as second class constraints, leading to three real configurational degrees of freedom per space point. Neve

R. Weht, A. Filippetti, W. E. Pickett

Local density functional results are presented for the electron-doped metallochloronitrides A(x)ZrNCl and A(x)HfNCl, A = Li or Na, which superconduct up to 25K. The alkali non-stoichiometry is treated in a virtual crystal approximation. The electronic structure is strongly two dimensional, especially in the conduction band region occupied by the carriers, be

A. A. Aligia, K. Hallberg, C. D. Batista, G. Ortiz

The quantum phase diagram of the Hubbard chain with correlated hopping is accurately determined through jumps in $π$ in the charge and spin Berry phases. The nature of each thermodynamic phase, and the existence of charge and spin gaps, is confirmed by calculating correlation functions and other fundamental quantities using numerical methods, and symmetry ar

M. Tavares, G. -Q. Hai

In this work, the Coulomb scattering lifetimes of electrons in two coupled quantum wires have been studied by calculating the quasiparticle self-energy within a multisubband model of quasi-one-dimensional (Q1D) electron system. We consider two strongly coupled quantum wires with two occupied subbands. The intrasubband and intersubband inelastic scattering ra

Takashi Hotta, Matthias Mayr, Elbio Dagotto

On the basis of an electronic model with separable attractive interaction, the precursors at high temperature and strong coupling of the d-wave superconducting state are investigated in the one-particle spectral function $A({\bf k},ω)$ and the total density of states $ρ(ω)$, with the use of the self-consistent $t$-matrix approximation. In the low-density reg

Alexei Vazquez, Oscar Sotolongo-Costa

The existence of self-organized criticality in the Barkhausen effect and its analogy with sandpile models is investigated. It is demonstrated that a model recently introduced to describe the dynamics of a domain wall [Cizeau et al, Phys. Rev. Lett. 79, 4669 (1997)] belongs to the universality class of undirected Abelian sandpile models. In this way it is sho

S. Sergeenkov, M. Ausloos

Approximating the shape of the measured in $Bi_2Sr_2CaCu_2O_y$ magneto-thermopower (TEP) $ΔS(T,H)$ by asymmetric linear triangle of the form $ΔS(T,H)\simeq S_p(H)\pm B^{\pm}(H)(T_c-T)$ with positive $B ^{-}(H)$ and $B ^{+}(H)$ defined below and above $T_c$, we observe that $B ^{+}(H)\simeq 2B ^{-}(H)$. In order to account for this asymmetry, we explicitly in

W. M. C. Foulkes, Randolph Q. Hood, R. J. Needs

Fixed-node diffusion Monte Carlo (DMC) is a stochastic algorithm for finding the lowest energy many-fermion wave function with the same nodal surface as a chosen trial function. It has proved itself among the most accurate methods available for calculating many-electron ground states, and is one of the few approaches that can be applied to systems large enou

D. Sornette, P. Simonetti, J. V. Andersen

This paper offers a precise analytical characterization of the distribution of returns for a portfolio constituted of assets whose returns are described by an arbitrary joint multivariate distribution. In this goal, we introduce a non-linear transformation that maps the returns onto gaussian variables whose covariance matrix provides a new measure of depende

Gerald Bedürftig, Holger Frahm

We study integrable boundary conditions for the supersymmetric t-J model of correlated electrons which arise when combining static scattering potentials with dynamical impurities carrying an internal degree of freedom. The latter differ from the bulk sites by allowing for double occupation of the local orbitals. The spectrum of the resulting Hamiltonians is

D. Gulo, O. Alexejev

Theoretical calculations of the electrical conductivity and electroosmotic transfer as functions of the disperse phase volume fraction and non-dissolving boundary layer thickness were provided on the basis of the cell theory of electroosmosis for the limiting case of large degree of electric double layers overlapping in interparticle space. The obtained resu

Chinmay Das, A. K. Sood, H. R. Krishnamurthy

From Landau-Alexander-McTague theory and Monte-Carlo simulation results we show that the modulated liquid obtained by subjecting a colloidal system to a periodic laser modulation has long range bond-orientational order and non-zero shear rigidity. From infinite field simulation results we show that in the modulated liquid phase, the translational order param

Z. Zhai, P. V. Patanjali, N. Hakim, J. B. Sokoloff

We report the observation of a frequency ($ω$) and temperature (T) -dependent loss peak in $χ''$ and accompanying dispersion in $χ'$ from microwave (2-18GHz) measurements of the complex susceptibility $\tildeχ(ω, T)=χ'+iχ''$ of $Sr_{14-x}Ca_{x}Cu_{24}O_{41}$. We associate this phenomenon with a rapid decrease of spin disorder and corr

H. Q. Lin, J. L. Shen

We study a set of exactly soluble net spin models. There exist two kinds of ground state, one is a complete dimerized state, and the other one is the ground state of corresponding spin-1 model. For the excitation gap, various phases were discovered and determined.

Karol Zyczkowski, Takashi Nishikawa

We investigate linear parabolic maps on the torus. In a generic case these maps are non-invertible and discontinuous. Although the metric entropy of these systems is equal to zero, their dynamics is non-trivial due to folding of the image of the unit square into the torus. We study the structure of the maximal invariant set, and in a generic case we prove th

Sitabhra Sinha

The phenomenon of Stochastic Resonance (SR) is reported in a completely noise-free situation, with the role of thermal noise being taken by low-dimensional chaos. A one-dimensional, piecewise linear map and a pair of coupled excitatory-inhibitory neurons are the systems used for the investigation. Both systems show a transition from symmetry-broken to symmet

D. W. Savin, S. M. Kahn, J. Linkemann, A. A. Saghiri

In photoionized gases with cosmic abundances, dielectronic recombination (DR) proceeds primarily via nlj --> nl'j' core excitations (Dn=0 DR). We have measured the resonance strengths and energies for Fe XVIII to Fe XVII and Fe XIX to Fe XVIII Dn=0 DR. Using our measurements, we have calculated the Fe XVIII and Fe XIX Dn=0 DR DR rate coefficients. Si

I. F. Mirabel, O. Laurent

Giant radio galaxies are thought to be massive ellipticals powered by accretion of interstellar matter onto a supermassive black hole. Interactions with gas rich galaxies may provide the interstellar matter to feed the active galactic nucleus (AGN). To power radio lobes that extend up to distances of hundreds of kiloparsecs, gas has to be funneled from kilop

R. Ramaty, R. E. Lingenfelter

Using a Monte Carlo code which incorporates the delayed mixing into the ISM of supernovae nucleosynthetic yields and ejecta kinetic energies (including events with very large energies, e.g. collapsars/hypernovae), we tested three evolutionary models of spallogenic light element origin, specifically Be. The CRI, in which the cosmic rays are accelerated out of

H. Papathanassiou

I calculate spectral evolution series for pulses of GRBs, in the BATSE spectral range, for continuous particle injection and cooling by synchrotron, inverse Compton, and adiabatic expansion. The hydrodynamic properties of the relativistic outflow are homogeneous across the emitting region which is a conical jet. The flow is viewed at an angle off its symmetr

R. Edelson, S. Vaughan, R. Warwick, E. Puchnarewicz

We report the results of a new analysis of the ROSAT Wide Field Camera (WFC) all-sky survey data, designed to detect extragalactic sources of extreme ultraviolet (EUV) radiation in regions of low Galactic N_H. We identify a total of 19 active galactic nuclei (AGN), more than double the number of confirmed AGN in the published WFC (2RE) survey. Our sample con

Pablo Reig

Two different models have been put forward to explain the origin of the X-ray emission of the unusual X-ray source 1E 1024.0-5732/Wack 2134: a high-mass X-ray binary system (HMXB) and a colliding wind binary (CWB). We present new optical and X-ray data in an attempt to clarify the nature of this system. The data seem to favour the colliding wind model since

Andrew R Liddle

I review various aspects of techniques for reconstructing the potential of the inflaton field from observations, with special emphasis on difficulties which might arise. While my view is that if inflation is to prove viable then most likely it will be one of the simplest models, it is important to consider the impact should we need to move to a more complica

Mark Henriksen, Q. Daniel Wang, Melville Ulmer

We report results from an X-ray study of the Abell 2111 galaxy cluster using the Advanced Satellite for Astrophysics and Cosmology ASCA and the ROSAT Position Sensitive Proportional Counter (PSPC). By correcting for the energy-dependent point-spread function of the ASCA instruments, we have examined the temperature structure of the cluster. The cluster's

K. A. Postnov, M. E. Prokhorov

The formation and evolution of binary black holes (BH) is studied using the modern evolutionary scenario for very massive stars with high mass loss (Vanbeveren et al. 1998). Main sequence stars with masses $M>35 M_\odot$ are assumed to form a BH in the end of their nuclear evolution. The mass of BH formed is parametrized as $M_{bh}=k_{bh}\times M_{SN}$, wher

Rosa Gonzalez Delgado, Timothy Heckman

We present HST (WFPC2 and FOC) images and UV GHRS spectra plus ground-based optical spectra of four Luminous Infrared Galaxies (LIRGs) that have Seyfert 2 nuclei (Mrk 477, NGC 7130, NGC 5135 and IC 3639). The data provide direct evidence of the existence of a central nuclear starburst that dominates the UV and optical light and are dusty and compact. The bol

X. -D. Li

The nature of the 5-12 s "anomalous" X-ray pulsars remains a mystery. Among the models that have been proposed to explain the properties of AXPs, the most likely ones are: (1) isolated accreting neutron stars evolved from the Thorne-Żytkow objects due to complete spiral-in during the common envelope evolution of high-mass X-ray binaries, and (2) magn

A. F. Ho, P. Coleman

We have developed a new boot-strap method for solving a class of interacting one-dimensional chiral fermions. The conventional model for interacting right-moving electrons with spin has an SO(4) symmetry, and can be written as four interacting Majorana fermions, each with the same velocity. We have found a method for solving some cases when the velocities of

M. P. Lilly, K. B. Cooper, J. P. Eisenstein, L. N. Pfeiffer

We report the observation of an acute sensitivity of the anisotropic longitudinal resistivity of two-dimensional electron systems in half-filled high Landau levels to the magnitude and orientation of an in-plane magnetic field. In the third and higher Landau levels, at filling fractions nu=9/2, 11/2, etc., the in-plane field can lead to a striking interchang

Alberto J. Castro-Tirado

Gamma-Ray Bursts (GRBs) have remained a puzzle for many high-energy astrophysicists since their discovery in 1967. With the advent of the X-ray satellites BeppoSAX and RossiXTE, it has been possible to carry out deep multi-wavelength observations of the counterparts associated with the GRBs just within a few hours of occurence, thanks to the observation of t

R. Narayanan, Thomas Vojta, D. Belitz, T. R. Kirkpatrick

The effects of quenched disorder on the critical properties of itinerant quantum magnets are considered. Particular attention is paid to locally ordered rare regions that are formed in the presence of quenched disorder even when the bulk system is still in the nonmagnetic phase. It is shown that these local moments or instantons destroy the previously found

D. A. Garanin, E. C. Kennedy, D. S. F. Crothers, W. T. Coffey

Classical escape rates of uniaxial spin systems are characterized by a prefactor differing from and much smaller than that of the particle problem, since the maximum of the spin energy is attained everywhere on the line of constant latitude: theta=const, 0 =< phi =< 2*pi. If a transverse field is applied, a saddle point of the energy is formed, and high, mod

Christof Gattringer

Using techniques from hopping expansion we identically map the lattice Schwinger model with Wilson fermions to a model of oriented loops on the lattice. This is done by first computing the explicit form of the fermion determinant in the external field. Subsequent integration of the gauge fields renders a sum over all loop configurations with simple Gaussian

M. M. Sheikh-Jabbari

We argue that Yang-Mills theory on noncommutative torus, expressed in the Fourrier modes, is described by a gauge theory in a usual commutative space, the gauge group being a generalization of the area-preserving diffeomorphisms to the noncommutative case. In this way, performing the loop calculation in this gauge theory in the continuum limit we show that t

A. I. Davydychev, V. A. Smirnov

By use of the threshold expansion we develop an algorithm for analytical evaluation, within dimensional regularization, of arbitrary terms in the expansion of the (two-loop) sunset diagram with general masses m_1, m_2 and m_3 near its threshold, i.e. in any given order in the difference between the external momentum squared and its threshold value, (m_1+m_2+

M. Calixto, V. Aldaya

The possibility of non-trivial representations of the gauge group on wavefunctionals of a gauge invariant quantum field theory leads to a generation of mass for intermediate vector and tensor bosons. The mass parameters m show up as central charges in the algebra of constraints, which then become of second-class nature. The gauge group coordinates acquire dy

Duiliu-Emanuel Diaconescu, Govindan Rajesh

We use the method of stable degenerations to study the local geometry of Calabi-Yau fourfolds for F-theory compactifications dual to heterotic compactifications on a Calabi-Yau threefold with fivebranes wrapping holomorphic curves in the threefold. When fivebranes wrap intersecting curves, or when many fivebranes wrap the same curve, the dual fourfolds degen

Israel Quiros

A point of view is presented, according to which, the well known picture with the Schwarzschild black hole in canonical general relativity is one in a whole class of conformal representations of the same physical situation, that are physically equivalent. Symmetry arguments are presented that favour a conformal picture without singularity instead of the Schw

Sergei Klishevich, Mikhail Plyushchay

We construct the model with light-like world-lines for the massive 4D spinning particles and 3D anyons. It is obtained via the formal bosonization of pseudoclassical model for the massive Dirac particle with subsequent reduction to the light-like curves. The peculiarity of the light-like trajectories produced due to the Zitterbewegung is explained from the v

S. Salmons, P. Grange, E. Werner

Compact canonical quantization on the light cone (DLCQ) is examined in the limit of infinite periodicity lenth L. Pauli Jordan commutators are found to approach continuum expressions with marginal non causal terms of order $L^{-3/4}$ traced back to the handling of IR divergence through the elimination of zero modes. In contrast direct quantization in the con

A. J. Benson, R. G. Bower, C. S. Frenk, S. D. M. White

Current theories of galaxy formation predict that spiral galaxies are embedded in a reservoir of hot gas. This gas is able to cool onto the galaxy replenishing cold gas that is consumed by star formation. Estimates of the X-ray luminosity emitted in the cooling region suggest a bolometric luminosity of order 10 x 10^41 ergs/s in massive systems. We have used

Andrei Moroianu, Uwe Semmelmann

In this paper we complete the classification of spin manifolds admitting parallel spinors, in terms of the Riemannian holonomy groups. More precisely, we show that on a given n-dimensional Riemannian manifold, spin structures with parallel spinors are in one to one correspondence with lifts to Spin_n of the Riemannian holonomy group, with fixed points on the

E. J. Copeland, Joao Magueijo, D. A. Steer

We perform a new and accurate study of the dependence on cosmological parameters of structure formation with local cosmic strings. The crucial new ingredients are the inclusion of the effects of gravitational backreaction on the evolution of the network, and the accurate evolution of the network through the radiation to matter transition. Our work re-iterate

Marianne Dufour Fournier, Janos Polonyi

Different dynamical symmetry breaking patterns are explored for the two dimensional phi4 model with higher order derivative terms. The one-loop saddle point expansion predicts a rather involved phase structure and a new Gaussian critical line. This vacuum structure is corroborated by the Monte Carlo method, as well. Analogies with the structure of solids, th

S. Kasuya, M. Kawasaki

We reconsider the formation of (global) cosmic strings during and after preheating by calculating the dynamics of a scalar field on both two- and three- dimensional lattices. We have found that there is little differences between the results in two and three dimensions about the dynamics of fluctuations, at least, during preheating. Practically, it is diffic

M. Knupfer, J. Fink

We have studied the low energy electronic excitations of C60 using momentum dependent electron energy-loss spectroscopy in transmission. The momentum dependent intensity of the gap excitation allows the first direct experimental determination of the energy of the 1Hg excitation and thus also of the total width of the multiplet resulting from the gap transiti

P. H. Damgaard

The interplay between between gauge-field winding numbers, theta-vacua, and the Dirac operator spectrum in finite-volume gauge theories is reconsidered. To assess the weight of each topological sector, we compare the mass-dependent chiral condensate in gauge field sectors of fixed topological index with the answer obtained by summing over the topological cha

J. Gegelia

Within the framework of non-relativistic scalar effective field theory it is shown that the problem of the cutoff dependence of the leading order amplitude for a particle scattering off a two-body bound state can be solved without introducing three-body forces.

Kimyeong Lee

We investigate the role of massless magnetic monopoles in the N=4 supersymmetric Yang-Mills Higgs theories. They can appear naturally in the 1/4-BPS dyonic configurations associated with multi-pronged string configurations. Massless magnetic monopoles can carry nonabelian electric charge when their associated gauge symmetry is unbroken. Surprisingly, massles

F. Gonzalez-Rey, B. Kulik, I. Y. Park

Certain two and three point functions of gauge invariant primary operators of ${\cal N}=4$ SYM are computed in ${\cal N}=1$ superspace keeping all the $þ$-components. This allows one to read off many component descendent correlators. Our results show the only possible $g^2_{YM}$ corrections to the free field correlators are contact terms. Therefore they vani

Mina Aganagic, Andreas Karch, Dieter Lust, Andre Miemiec

We study local mirror symmetry on non-compact Calabi-Yau manifolds (conifold type of singularities) in the presence of D3 brane probes. Using an intermediate brane setup of NS 5-branes `probed&#39; by D4 resp. D5 branes, we can explicitly T-dualize three isometry directions to relate a non-compact Calabi-Yau manifold to its local mirror. The intermediate bra

R. Beals, D. H. Sattinger, J. Szmigielski

A closed form of the multi-peakon solutions of the Camassa-Holm equation is found using a theorem of Stieltjes on continued fractions. An explicit formula is obtained for the scattering shifts.

Vwani P. Roychowdhury, Farrokh Vatan

We show that Nechiporuk&#39;s method for proving lower bound for Boolean formulas can be extended to the quantum case. This leads to an n^2 / log^2 n lower bound for quantum formulas computing an explicit function. The only known previous explicit lower bound for quantum formulas (by Yao) states that the majority function does not have a linear-size quantum

Daniel Braun, Petr A. Braun, Fritz Haake

Linear superpositions of macroscopically distinct quantum states (sometimes also called Schrödinger cat states) are usually almost immediately reduced to a statistical mixture if exposed to the dephasing influence of a dissipative environment. Couplings to the environment with a certain symmetry can lead to slow decoherence, however. We give specific example

Daniel Braun, Petr A. Braun, Fritz Haake

The dephasing influence of a dissipative environment reduces linear superpositions of macroscopically distinct quantum states (sometimes also called Schrödinger cat states) usually almost immediately to a statistical mixture. This process is called decoherence. Couplings to the environment with a certain symmetry can lead to slow decoherence. In this Letter

A. G. Rojo, J. L. Cohen, P. R. Berman

An exact theory for the density of a one-dimensional Bose-Einstein condensate with hard core particle interactions is developed in second quantization and applied to the scattering of the condensate by a spatially periodic impulse potential. The boson problem is mapped onto a system of free fermions obeying the Pauli exclusion principle to facilitate the cal

J. M. Taylor, Zong-Chao Yan, A. Dalgarno, J. F. Babb

We present high-precision non-relativistic variational calculations of bound vibrational-rotational state energies for the $H_2^+$ and $D_2^+$ molecular ions in each of the lowest electronic states of $Σ_g$, $Σ_u$, and $Π_u$ symmetry. The calculations are carried out including coupling between $Σ$ and $Π$ states but without using the Born-Oppenheimer or any

S. A. Coon

Traditionally isospin violation (charge symmetry breaking and charge dependence) has been modeled by the exchange of mesons between two nucleons. Sources of isospin violation in these models include meson mass differences, meson mixing (of pseudoscalar, vector, and axial-vector mesons) and isospin violating couplings of mesons with nucleons. I will review th

N. Auerbach, B. A. Brown

The importance of core contributions to the anapole moment in nuclei is examined. A model of the core-polarization correction is presented. The model is based on the coupling of the valence particles to the spin-dipole $J=1^{-}$ giant resonances of the core. A shell-model calculation of this correction is presented. The single-particle moments are calculated

J. Kvasil, R. G. Nazmitdinov, A. Mackova, M. Kopal

A strength function method is adopted to describe a coupling between electric and magnetic modes of different multipolarity. The collective vibrations are analysed for a separable residual interaction in the framework of the random-phase approximation. The coupling between $M2$ and $E1$ giant resonances is considered as an illustrative example.

S. P. Novikov

This work is a continuation and extension of the note published in the Russian Math Surveys 1997 n 6. For any pair of solutions of the spectral problem for the second order selfadjoint real Schrodinger Operator on the graph their Symplectic Wronskian is a 1-cycle in the graph. This is a vector-valued symplectic 2-form on the space of solutions. This construc

Chie Bing Wang

Based on the results in the previous papers that the boundary value problem $y&#39;&#39; - y&#39; + y = y^3, y(0) = 0, y(\infty) =1$ with the condition $y(x) > 0$ for $0<x<\infty$ has a unique solution $y^*(x)$, and $a^*= y^{*^{&#39;}}(0)$ satisfies $0<a^*<1/4$, in this paper we show that $y&#39;&#39; - y&#39; + y = y^3, -\infty < x < 0$, with the initial co

Chie Bing Wang

In this paper, we study the analytic expansion in a small neighborhood of 0 in the complex plane for the solution to the equation $p dp/dz - p = z(z-1)(z-2)$ satisfying $p(z) = -z + O(z^2)$ as $z \to 0$. We show that the expansion is valid for $|z| \le s_0$, where $s_0 >1$. Then we get an explicit formula for $p(1)$ which is used to give the connection formu

Chie Bing Wang

In this paper we study the equation $r^2 {d^2 f/dr^2} + f = f^3$ with the boundary conditions $f(1)=0$, $f(\infty)=1$ and $f(r) > 0$ for $1<r<\infty$. The existence of the solution is proved by using topological shooting argument. And the uniqueness is proved by variation method. Using the asymptotics of $f(r)$ as $r \to 1$, in the following papers we will d

Vladimir Lyakhovsky, Mariano A. del Olmo

The properties of the set {L} of extended jordanian twists for algebra sl(3) are studied. Starting from the simplest algebraic construction --- the peripheric Hopf algebra U_ P&#39;(0,1)(sl(3)) --- we construct explicitly the complete family of extended twisted algebras {U_ E(θ)(sl(3))} corresponding to the set of 4-dimensional Frobenius subalgebras {L(θ)} i

Alexander Reznikov

Three great theorems of Thurston read: Haken manifolds are hyperbolic; big ramified coverings are hyperbolic; big surgeries are hyperbolic. Recent developments indicate that the later two theorems are essentially a corollary of the first, that is there are much more Haken manifolds than expected by Thurston. In fact Freedman showed very recently that big ram

G. M. Cicuta, M. Contedini

The class of random walks in one dimension, returning to the origin, restricted by the requirement that any site visited (different from the origin) is visited an even number of times, is analyzed in the present note. We call this class the even-visiting random walks and provide a closed expression to evaluate them.

A. Ghosh, J. Maharana

Ward identities in the case of scattering of antisymmetric three form RR gauge fields off a D2-brane target has been studied in type-IIA theory.

Masud Chaichian, Tatsuo Kobayashi

We compare two approaches in supersymmetric confinement, the Seiberg formulation and the superconvergence rule. For the latter, the critical point is $γ_{00}=0$ in the Landau gauge. We find $4γ_{00}=β_0$ is the critical point for most of confining theories without a tree-level superpotential in the Seiberg formulation, in particular, in the large $N_c$ and $

P. P. Divakaran

A direct consequence of the occurrence of fermion families is the invariance of currents under certain groups of (universality) transformations. We show how these universality groups can themselves be used to find and study grand family unification models. Identifying two independent - weak and strong - universality groups and assuming that the grand unifica

J. Plefka, M. Serone, A. Waldron

We briefly review the computation of graviton and antisymmetric tensor scattering amplitudes in Matrix Theory from a diagramatic S-Matrix point of view.

Pankaj Sharan, Anupama Mehra, Krishnendu Dasgupta, M. Sami

Complete constraint analysis and choice of gauge conditions consistent with equations of motion is done for Abelian Chern Simons field interacting minimally with a complex scalar field. The Dirac-Schwinger consistency condition is satisfied by the reduced phase space Hamiltonian density with respect to the the Dirac bracket. It is shown that relativistic inv

K. Dasgupta, M. Sami, Pankaj Sharan, Anupama Mehra

Complete constraint analysis and choice of gauge conditions consistent with equations of motion is done for non-abelian Chern-Simons field interacting with N-component complex scalar field. Dirac-Schwinger condition is satisfied by the reduced phase-space Hamiltonian density with respect to the Dirac bracket.

R. M. Godbole, Giulia Pancheri

In this talk I present the results of an analysis of total and inelastic hadronic cross-sections for photon induced processes in the framework of an eikonalised minijet model(EMM). We fix the various input parameters to the EMM calculations by using the data on photoproduction cross-sections and then make predictions for $\siggmhad$ using same values of the

Russel P. Kauffman, Satish V. Desai, Dipesh Risal

In this talk we consider amplitudes for processes involving a Higgs boson, either scalar or pseudoscalar, plus four light partons. These amplitudes are relevant to the production of a Higgs boson plus two jets in hadronic collisions. They are also relevant to calculating the transverse momentum spectrum for Higgs bosons at next-to-leading order in the strong

Amol S. Dighe, Q. Y. Liu, Alexei Yu. Smirnov

We consider the day-night asymmetries predicted by MSW solutions of the solar neutrino problem. The integration over the neutrino energy, as well as over the production region or over the time intervals of more than a day leads to the averaging of oscillations on the way to the earth. This is equivalent to considering the neutrino state arriving at the surfa

K. J. Golec-Biernat, A. D. Martin, M. G. Ryskin

We show that a knowledge of diagonal partons at a low scale is sufficient to determine the off-diagonal (or skewed) distributions at a higher scale, to a good degree of accuracy. We quantify this observation by presenting results for the evolution of off-diagonal distributions from a variety of different inputs.

R. S. Marques de Carvalho, F. S. Navarra, M. Nielsen, E. Ferreira

QCD sum rules for the determination of form factors of $Λ_b$ and $Λ_c$ semileptonic decays are investigated. With a form for the baryonic current appropriate for the limits of the heavy quark symmetries, the different tensor structures occurring in the two- and three-point functions are separately studied, and in each case general relations are written for t

I. Akushevich, N. Shumeiko, A. Soroko

An approach to calculate radiative corrections to unpolarized cross section of semi-inclusive electroproduction is developed. An explicit formulae for the lowest order QED radiative correction are presented. Detailed numerical analysis is performed for the kinematics of experiments at the fixed targets.

Hsiang-nan Li

The perturbative QCD formalism for exclusive heavy meson decays, especially the three-scale factorization theorem for nonleptonic modes is reviewed and compared to the conventional Bauer-Stech-Wirbel model.

J. H. Kuhn, T. Teubner

We calculate the contributions of the axial current to top quark pair production in e+ e- annihilation at threshold. The QCD dynamics is taken into account by solving the Lippmann-Schwinger equation for the P wave production using the QCD potential up to two loops. We demonstrate that the dependence of the total and differential cross section on the polariza

G. Calucci, D. Treleani

Hamiltonian eikonal model for multiple production in high energy hadron-hadron collisions is presented and worked out with the aim of providing a simple frame for various different observables. An important role is played by unitarity which is built in by construction in the Hamiltonian formulation. The eikonal approximation allows both a very effective simp

James L. Carr

When charged current weak interations are excluded, the neutral current weak interaction is formally similar to ordinary electromagnetism with a massive photon. In this spirit, the Maxwell equations for the fields of the Z-boson are derived from the standard model. These describe the Z-boson scalar and vector potentials, and the Z-boson electric and magnetic

Csaba Csaki, Michael Graesser, John Terning

We consider a recent model with sub-millimeter sized extra dimensions, where the field that determines the size of the extra dimensions (the radion) also acts as an inflaton. The radion is also a stable modulus, and its coherent oscillations can potentially overclose the Universe. It has been suggested that a second round of late inflation can solve this pro

R. Brandenberger, I. Halperin, A. Zhitnitsky

We propose a new mechanism for explaining the observed asymmetry between matter and antimatter, based on nonperturbative physics at the QCD scale. Our mechanism is a charge separation scenario, making use of domain walls separating the recently discovered long-lived metastable vacua from the lowest energy vacuum. The walls acquire a fractional negative baryo

M. Garcia Perez, A. Gonzalez-Arroyo, A. Montero, P. van Baal

We discuss the manifestation of instanton and monopole solutions on a periodic lattice at finite temperature and their relation to the infinite volume analytic caloron solutions with asymptotic non-trivial Polyakov loops. As a tool we use improved cooling and twisted boundary conditions. Typically we find 2Q lumps for topological charge Q. These lumps are BP

Sourendu Gupta

The symmetry group of the staggered Fermion transfer matrix in a spatial direction is constructed at finite temperature. Hadron-like operators carrying irreducible representations of this group are written down from the breaking of the zero temperature group. Analysis of the correlators in a free fermion theory suggests new measurements which can test curren

H. Arisue, K. Tabata

We have calculated the large-q expansion for the energy cumulants and the magnetization cumulants at the phase transition point in the two-dimensional q-state Potts model to the 21st or 23rd order in $1/\sqrt{q}$ using the finite lattice method. The obtained series allow us to give very precise estimates of the cumulants for $q>4$ on the first order transiti

Murray A. Moinester, Victor Steiner, Serguei Prakhov

The COMPASS experiment at CERN SPS will use hadron beams (pion, kaon and proton) and muons at 50-280 GeV/c and virtual photon targets to investigate, via Primakoff effect, important hadron properties: polarizability, chiral anomaly, radiative transitions and hybrid meson production. We present simulation studies to optimize the beam, detector setup and trigg

Akira Konaka

A proposed experiment to measure K_L -> pi^0 nu nubar at the AGS (E926) is described. It adopts a unique but general strategy of rare decay measurements with two independent rejection criteria, which allows reliable measurements of background levels. The method employs hermetic veto and full kinematic reconstruction using kaon time of flight and kinematic re

R. Barate, ALEPH Collaboration

All ALEPH measurements of branching ratios of tau decays involving kaons are summarized including a combination of results obtained with K^0_S and K^0_L detection. The decay dynamics are studied, leading to the determination of contributions from vector K^*(892) and K^{*}(1410), and axial-vector K_1(1270) and K_1(1400) resonances. Agreement with isospin symm

R. Barate et al, ALEPH Collaboration

One-prong tau decays into final states involving kaons are studied with about 161k tau+tau- events collected by the ALEPH detector from 1991 to 1995. Charged kaons are identified by dE/dx measurement, while K0L&#39;s are detected through their interaction in calorimeters. Branching ratios are measured for the inclusive mode, B(tau- -> K-Xnu_tau)=(1.52 +- 0.0

Thomas Greening

Preliminary results from the four LEP experiments using data collected at 189 GeV have shown no evidence for the Standard Model Higgs boson. The preliminary 95% confidence level lower limits on the SM Higgs boson mass from ALEPH, DELPHI, OPAL, and L3 are 90.4 GeV, 94.1 GeV, 95.5 GeV, and 95.2 GeV, respectively. When LEP finishes in the year 2000, each experi

Lee Lindblom

Stability of the r-modes in rapidly rotating white dwarf stars is investigated. Improved estimates of the growth times of the gravitational-radiation driven instability in the r-modes of the observed DQ Her objects are found to be longer (probably considerably longer) than 6x10^9y. This rules out the possibility that the r-modes in these objects are emitting

Hans-Juergen Matschull

A simple example is given to show that the gauge equivalence classes of physical states in Chern Simons theory are not in one-to-one correspondence with those of Einstein gravity in three spacetime dimensions. The two theories are therefore not equivalent. It is shown that including singular metrics into general relativity has more, and in fact a quite count

Stephan Mertens

Given a set of numbers, the balanced partioning problem is to divide them into two subsets, so that the sum of the numbers in each subset are as nearly equal as possible, subject to the constraint that the cardinalities of the subsets be within one of each other. We combine the balanced largest differencing method (BLDM) and Korf&#39;s complete Karmarkar-Kar

Anatoly D. Plotnikov

We examine possibility to design an efficient solving algorithm for problems of the class \np. It is introduced a classification of \np problems by the property that a partial solution of size $k$ can be extended into a partial solution of size $k+1$ in polynomial time. It is defined an unique class problems to be worth to search an efficient solving algorit

Eugene Demler, Shou-Cheng Zhang

We review the explanation for resonant neutron scattering experiments in $YBa_2Cu_3O_{6+δ}$ and $Bi_2 Sr_2 Ca_2 O_{8+δ}$ materials from the point of view of triplet excitation in the particle-particle channel, the pi excitation. Relation of these resonances to the superconducting condensation energy and their role in stabilizing the superconducting state is

R. Narevich, R. E. Prange, Oleg Zaitsev

Eigenstates and energy levels of a square quantum billiard in a magnetic field, or with an Aharonov-Bohm flux line, are found in quasiclassical approximation, that is, for high enough energy. Explicit formulas for the energy levels and wavefunctions are found. There are localized states, never before noticed in this well studied problem, whose localization i

V. Spirin, P. L. Krapivsky, S. Redner

We study the low-temperature coarsening of an Ising chain subject to spin-exchange dynamics and a small driving force. This dynamical system reduces to a domain diffusion process, in which entire domains undergo nearest-neighbor hopping, except for the shortest domains -- dimers -- which undergo long-range hopping. This system is characterized by two indepen