April 1999 arXiv papers — page 18

M. Nagasawa, R. Brandenberger

In models in which some of the scalar field are charged and some uncharged, interactions with a finite temperature plasma will lead to corrections to the effective potential of the charged fields which may stabilize embedded defects made up of uncharged fields. In these models embedded defects, solutions of the field equations which are unstable at zero temp

Jan Kalinowski

The physics potential of discovering and exploring supersymmetry at future e^+e^- linear colliders is reviewed. Such colliders are planned to start to operate at a center-of-mass energy of 500 GeV to 800 GeV, with a final energy of about 2 TeV expected. They are ideal facilities for the discovery of supersymmetric particles. High precision measurements of th

M. Tentyukov, J. Fleischer

A C-program DIANA (DIagram ANAlyser) for the automatic Feynman diagram evaluation is presented. It consists of two parts: the analyzer of diagrams and the interpreter of a special text manipulating language. This language is used to create a source code for analytical or numerical evaluations and to keep the control of the process in general.

P. Marage

A review is presented of diffractive vector meson production at HERA, with stress on the investigation of ``hard'' features and comparisons with theoretical predictions based on perturbative QCD approaches.

N. N. Achasov, G. N. Shestakov

Evidence for an explicitly exotic state with isospin 2 and spin-parity 2^+ near the $ρρ$ threshold and nontrivial complementary indications of the unusual quark composition of the $f_0(980)$ and $a_0(980)$ states obtained from the reactions of two-photon formation of neutral meson resonances are discussed, together with puzzling phenomena in the channels $γγ

E. Tournefier, ALEPH Collaboration

The measurement of the Z resonance parameters and lepton forward-backward asymmetries are presented. These are determined from a sample of 4.5 million Z decays accumulated with the ALEPH detector at LEP1.

M. Pepe-Altarelli

The status of the search at LEP2 for the Higgs in the Standard Model (SM) and in the minimal supersymmetric extension of the Standard Model MSSM) is reviewed. A preliminary lower limit of 95.5/c^2 at 95% C.L. on the SM Higgs is obtained after a preliminary analysis of the data collected at sqrt(s)= 189 GeV. For standard choices of MSSM parameter sets, the se

Rosario Martin, Enric Verdaguer

In the first part of this paper, we show that the semiclassical Einstein-Langevin equation, introduced in the framework of a stochastic generalization of semiclassical gravity to describe the back reaction of matter stress-energy fluctuations, can be formally derived from a functional method based on the influence functional of Feynman and Vernon. In the sec

William R. Stoeger, Amina Helmi, Diego F. Torres

We introduce a simple and straight-forward averaging procedure, which is a generalization of one which is commonly used in electrodynamics, and show that it possesses all the characteristics we require for linearized averaging in general relativity and cosmology -- for weak-field and perturbed FLRW situations. In particular we demonstrate that it yields quan

M. I. Wanas

A new path equation in absolute parallelism (AP) geometry is derived. The equation is a generalization of three path equations derived in a previous work. It can be considered as a geodesic equation modified by a torsion term, whose numerical coefficient jumps by steps of one half. The torsion term is parametrized using the fine structure constant. It is sug

Yongsung Yoon

It is found that conformally coupled induced gravity with gradient torsion gives a dilaton gravity in Riemann geometry. In the Einstein frame of the dilaton gravity the conformal symmetry is hidden and a non-vanishing cosmological constant is not plausible due to the constraint of the conformal coupling.

Shilpa Jain, David R. Nelson

Columnar crystals contain defects in the form of vacancy/interstitial loops or strings of vacancies and interstitials bounded by column ``heads'' and ``tails''. These defect strings are oriented by the columnar lattice and can change size and shape by movement of the ends and forming kinks along the length. Hence an analysis in terms of direc

Shubha Tewari, Dylan Schiemann, Douglas J. Durian, Charles M. Knobler

Under steady shear, a foam relaxes stress through intermittent rearrangements of bubbles accompanied by sudden drops in the stored elastic energy. We use a simple model of foam that incorporates both elasticity and dissipation to study the statistics of bubble rearrangements in terms of energy drops, the number of nearest neighbor changes, and the rate of ne

E. K. Lenzi, R. S. Mendes, A. K. Rajagopal

In this paper, the Green function theory of quantum many-particle systems recently presented is reworked within the framework of nonextensive statistical mechanics with a new normalized $q$-expectation values. This reformulation introduces a renormalization of temperature of the earlier theory and a self-consistency condition. The linear response theory is a

Ugur Tirnakli, Diego F. Torres

Within the context of non-extensive thermostatistics, we use the factorization approximation to study a recently proposed early universe test. A very restrictive bound upon the non-extensive parameter is presented: $|q-1| < 4.01 \times 10^{-3}$.

Diego F. Torres, Ugur Tirnakli

The generalized quantal distribution functions are investigated concerning systems of non-interacting bosons and fermions. The formulae for the number of particles and energy are presented and applications to the Chandrasekhar limit of white dwarfs stars and to the Bose-Einstein condensation are commented.

Giuliano Benenti, Xavier Waintal, Jean-Louis Pichard

For intermediate Coulomb energy to Fermi energy ratios $r_s$, spinless fermions in a random potential form a new quantum phase which is nor a Fermi glass, neither a Wigner crystal. Studying small clusters, we show that this phase gives rise to an ordered flow of enhanced persistent currents, for disorder strength and ratios $r_s$ where a metallic phase has b

G. F. Reiter, J. Mayers, J. Noreland

We show that deep inelastic neutron scattering from hydrogen(or other light nuclei) can be used to measure a spectrum of anharmonic contributions to the target atom momentum distribution with high and known accuracy . The method is applied here to determine the momentum distribution of the hydrogen in the hydrogen bonded system KHC2O4(potassium binoxalate),

Adriaan M. J. Schakel

In the first part of this review paper, the time-dependent Ginzburg-Landau theory is derived starting from the microscopic BCS model with the help of a derivative expansion. Special attention is paid to two space dimensions, where the entire crossover from the weak-coupling BCS limit to the strong-coupling BEC limit of tightly bound fermion pairs is accessib

M. Weigel, W. Janke

The concept of conformal field theory provides a general classification of statistical systems on two-dimensional geometries at the point of a continuous phase transition. Considering the finite-size scaling of certain special observables, one thus obtains not only the critical exponents but even the corresponding amplitudes of the divergences analytically.

L. Vanel, E. Clement

We report sets of precise and reproducible measurements on the static pressure at the bottom of a granular column. We make a quantitative analysis of the pressure saturation when the column height is increased. We evidence a great sensitivity of the measurements with the global packing fraction and the eventual presence of shear bands at the boundaries. We a

Chun Zhang, Jun Wan, Feng Qiao, Jian Zi

A novel polarizer made from two-dimensional photonic bandgap materials was demonstrated theoretically. This polarizer is fundamentally different from the conventinal ones. It can function in a wide frequency range with high performance and the size can be made very compact, which renders it useful as a micropolarizer in microoptics.

M. Zwierzycki, S. Krompiewski

Within the framework of a two-band tight-binding model, we have performed calculations of giant magnetoresistance, exchange coupling and thermoelectric power (TEP) for a system consisting of three magnetic layers separated by two non-magnetic spacers with the first two magnetic layers strongly antiferromagnetically exchange-coupled. We have shown how does th

P. H. E. Tiesinga, Jorge V. José

We study the stability and information encoding capacity of synchronized states in a neuronal network model that represents part of thalamic circuitry. Our model neurons have a Hodgkin-Huxley-type low threshold Calcium channel, display post inhibitory rebound, and are connected via GABAergic inhibitory synapses. We find that there is a threshold in synaptic

T. Tohyama, C. Gazza, C. T. Shih, Y. C. Chen

The tendencies to phase-separation and stripe formation of the t-J model on planes and four-leg ladders have been here reexamined including hole hopping terms t&#39;, t&#39;&#39; beyond nearest-neighbor sites. The motivation for this study is the growing evidence that such terms are needed for a quantitative description of the cuprates. Using a variety of co

Jose L. Mateos

The classical problem of a time-modulated barrier, inspired by the Buttiker and Landauer model to study the tunneling times, is analyzed. We show that the traversal-time distribution of an ensemble of non-interacting particles that arrives at the oscillating barrier, obeys a distribution with a power-law tail.

B. G. Sidharth

We consider two cosmologies which give an inverse time dependance for the gravitational constant G, and show that we can recover the correct value of the perhelion precession and anomalous inward radial accelerations, amongst other things.

Michael P. Muno, Edward H. Morgan, Ronald A. Remillard

We present results from the analysis of X-ray energy spectra and quasi- periodic oscillations (QPOs) from a set of observations which samples a broad range of time variability in GRS 1915+105. We first demonstrate that the frequency and integrated amplitude of a 0.5-10 Hz QPO is correlated with the apparent temperature of the accretion disk for the majority

Piero Ullio

More than a decade ago it was noticed that an unexpectedly large value of the measured cosmic antiproton flux at low kinetic energies could be interpreted in terms of a neutralino-induced component. An overproduction of low energy antiprotons seems however to be disfavoured by recent data from the BESS experiment. The strategy we propose here is to focus ins

Serge Tabachnik, N. Wyn Evans

The last few months have seen the discovery of a second Martian Trojan (1998 VF31), as well as two further possible candidates (1998 QH56 and 1998 SD4). Together with the previously discovered Martian satellite 5261 Eureka, these are the only known possible solar system Trojan asteroids not associated with Jupiter. Here, maps of the locations of the stable T

J. A. Sellwood

A model that accounts for the brief flaring of QSOs in the early stages of galaxy formation is proposed. I argue that a bar must develop early in the life of nearly every galaxy and that gas to create and fuel the QSO is driven into the center of the galaxy by the bar. The QSO lifetime, and the mass of its central engine, are also controlled by large-scale d

P. M. Chadwick, K. Lyons, T. J. L. McComb, K. J. Orford

Atmospheric Cerenkov telescopes are used to detect electromagnetic showers from primary gamma rays of energy ~300 GeV - ~10 TeV and to discriminate these from cascades due to hadrons using the Cerenkov images. The geomagnetic field affects the development of showers and is shown to diffuse and distort the images. When the component of the field normal to the

Axel Weiss, Fabian Walter, Nikolaus Neininger, Uli Klein

We present evidence for an expanding superbubble in M82 (diameter: ~130 pc, expansion velocity: ~45 km/s, mass: ~8*10^6 SM). It is seen in the 12CO(J=1-0), 12CO(J=2-1), 13CO(J=1-0) and C18O(J=1-0) lines. The superbubble is centred around the most powerful supernova remnant in M82, 41.9+58. The CO observations show that the molecular superbubble already broke

P. Severgnini, P. Saracco

We have obtained $H_α$ fluxes and luminosities for a sample of 95 accordant galaxies from observations of 31 Hickson Compact Groups (HCGs) in the North hemisphere. This sample is the largest $H_α$ selected catalogue of galaxies having $H_α$ calibrated fluxes so far. The results obtained from a preliminary analysis of a subsample of 66 galaxies show that the

Mareki Honma

We report on the mass-to-light ratio determination based on a newly selected binary galaxy sample, which includes a large number of pairs whose separations exceed a few hundred kpc. The probability distributions of the projected separation and the velocity difference have been calculated considering the contamination of optical pairs, and the mass-to-light r

K. Iwasawa, A. C. Fabian, A. J. Young, H. Inoue

We report results on the broad iron emission line of the Seyfert galaxy MCG-6-30-15, obtained from the second long ASCA observation in 1997. The time-averaged profile of the broad line is very similar to that seen with ASCA in 1994, so confirming the detailed model fit then obtained. A bright flare is seen in the light curve, during which the continuum was s

A. J. Weinberger, G. Neugebauer, K. Matthews

The nearby Seyfert 2 Galaxy NGC 1068 was observed with speckle imaging techniques in the near-infrared H-band (1.6 microns) at the Hale 200-inch Telescope and K-band (2.2 microns) at the 10 m Keck I Telescope. Images with diffraction limited or near-diffraction limited resolutions of 0.&#39;&#39;05 - 0.&#39;&#39;1 were obtained and used to search for structu

A. Udalski, I. Soszynski, M. Szymanski, M. Kubiak

We present a sample of 93 double-mode Cepheids detected in the 2.4 square degree area in the central part of the SMC. 23 stars from the sample pulsate in the fundamental mode and the first overtone while 70 objects are the first and second overtone pulsators. This is the largest sample of such type Cepheids detected in one environment so far. We analyze peri

A. Gorsky, K. Selivanov

We discuss the processes of brane bubble nucleation induced by the external branes. The quasiclassical solution for the nucleation by the single external brane has been found in the case when the brane junctions are possible. Exponential factor in the production rate has been calculated. The process induced by the fundamental or D string in the background of

David Berenstein, Robert G. Leigh

We construct string target spacetimes with AdS_3 x X geometry, which have an N=2 spacetime superconformal algebra. X is found to be a U(1) fibration over a manifold which is a target for an N=2 worldsheet conformal field theory. We emphasize theories with free field realizations where in principle it is possible to compute the full one-particle string spectr

W. Mueck, K. S. Viswanathan

The prescription of the AdS/CFT correspondence is refined by using a regularization procedure, which makes is possible to calculate the divergent local terms in the CFT two-point function. We present the procedure for the example of the scalar field.

Hsin-Chia Cheng

The pseudo-Goldstone boson mechanism for the ``doublet-triplet splitting&#39;&#39; problem of the grand unified theory can be naturally implemented in the scenario with extra dimensions and branes. The two SU(6) global symmetries of the Higgs sector are located on two separate branes while the SU(6) gauge symmetry is in the bulk. After including several vect

Martin Z. Bazant, Howard A. Stone

The long-time behavior of a reaction-diffusion front between one static (e.g. porous solid) reactant A and one initially separated diffusing reactant B is analyzed for the mean-field reaction-rate density R(ρ_A,ρ_B) = kρ_A^mρ_B^n. A uniformly valid asymptotic approximation is constructed from matched self-similar solutions in a reaction front (of width w \si

Charles H. Bennett, Peter W. Shor, John A. Smolin, Ashish V. Thapliyal

Prior entanglement between sender and receiver, which exactly doubles the classical capacity of a noiseless quantum channel, can increase the classical capacity of some noisy quantum channels by an arbitrarily large constant factor depending on the channel, relative to the best known classical capacity achievable without entanglement. The enhancement factor

Alessandro Strumia

Oscillations of three neutrinos with all squared mass splittings around 10^{-3} eV^2 are not firmly excluded by solar neutrino experiments. We carefully verify that they are also perfectly compatible with atmospheric neutrino experiments: due to accidental reasons the SuperKamiokande experiment is rather insensitive to `solar&#39; nu_e/ν_mu oscillations, eve

John Preskill

I consider some promising future directions for quantum information theory that could influence the development of 21st century physics. Advances in the theory of the distinguishability of superoperators may lead to new strategies for improving the precision of quantum-limited measurements. A better grasp of the properties of multi-partite quantum entangleme

Arnd Brandenburg

The production of top quark pairs accompanied by a hard gluon in $e^+e^-$ annihilation is studied including next-to-leading order corrections in the strong coupling. At leading order, the fraction r of $t\bar{t}g$ events with respect to all $t\bar{t}$ events is computed analytically as a function of the minimal gluon energy. Next-to-leading order results for

Andrew M. Childs, John Preskill, Joseph Renes

We describe some applications of quantum information theory to the analysis of quantum limits on measurement sensitivity. A measurement of a weak force acting on a quantum system is a determination of a classical parameter appearing in the master equation that governs the evolution of the system; limitations on measurement accuracy arise because it is not po

I. Vekhter, A. Houghton

We present the results of a microscopic calculation of the longitudinal thermal conductivity, $κ$, of a d-wave superconductor in the mixed state. Our results show an increase in the thermal conductivity with the applied field at low temperatures, and a decrease followed by a nearly field independent $κ(H)$ at higher temperatures, in qualitative agreement wit

Jonathan L. Feng, Takeo Moroi, Lisa Randall, Matthew Strassler

In supersymmetric models, Winos, partners of the SU(2) gauge bosons, may be the lightest supersymmetric particles (LSPs). For generic parameters, charged and neutral Winos are highly degenerate. Charged Winos travel macroscopic distances, but can decay to neutral Winos and extremely soft leptons or pions before reaching the muon chambers, thereby circumventi

A. Polleri, R. Mattiello, I. N. Mishustin, J. P. Bondorf

A direct method to reconstruct the transverse structure of the baryon source formed in a relativistic heavy ion collision is presented. The procedure makes use of experimentally measured proton and deuteron spectra and assumes that deuterons are formed via two-nucleon coalescence. The transverse density shape and flow profile are reconstructed for Pb+Pb coll

Barbara Drossel

The abelian sandpile model in two dimensions does not show the type of critical behavior familar from equilibrium systems. Rather, the properties of the stationary state follow from the condition that an avalanche started at a distance r from the system boundary has a probability proportional to 1/sqrt(r) to reach the boundary. As a consequence, the scaling

Qaisar Shafi, Zurab Tavartkiladze

By supplementing minimal supersymmetric SU(5) (MSSU(5)) with a flavor ${\cal U}(1)$ symmetry and two pairs of $\bar{15}+15$ `matter&#39; supermultiplets, we present an improved model which explains the charged fermion mass hierarchies and the magnitudes of the CKM matrix elements, while avoiding the undesirable asymptotic mass relations $m_s=m_μ, m_d/m_s = m

Warren G. Anderson, Werner Israel

We calculate the flux from a spherical mirror which is expanding or contracting with nearly uniform acceleration. We find that the flux at an exterior point (which could in principle be a functional of the mirror&#39;s past history) is actually found to be a local function, depending on the first and second time derivatives of acceleration at the retarded ti

Francesco Belgiorno, Stefano Liberati, Matt Visser, Dennis Sciama

In this Letter we propose a fundamental test for probing the thermal nature of the spectrum emitted by sonoluminescence. We show that two-photon correlations can in principle discriminate between real thermal light and the quasi-thermal squeezed-state photons typical of models based on the dynamic Casimir effect. Two-photon correlations provide a powerful ex

Alessandro Strumia, Nikolaos Tetradis

We calculate bubble-nucleation rates for (2+1)-dimensional scalar theories at high temperature. Our approach is based on the notion of a real coarse-grained potential. The region of applicability of our method is determined through internal consistency criteria. We compare our results with data from lattice simulations. Good agreement is observed when the re

Shin&#39;ichi Nojiri, Sergei D. Odintsov

The running gauge coupling and quark-antiquark potential in d-dimensions are calculated from the explicit solution of d+1-dimensional dilatonic gravity. This background interpolates between usual AdS in UV and flat space with singular dilaton in IR and it realizes two-boundaries AdS/CFT correspondence. The behaviour of running coupling and potential is consi

Eduard Schmidt, Ludwig Knoll, Dirk-Gunnar Welsch

Using cumulant expansion in Gaussian approximation, the internal quantum statistics of damped soliton-like pulses in Kerr media are studied numerically, considering both narrow and finite bandwidth spectral pulse components. It is shown that the sub-Poissonian statistics can be enhanced, under certain circumstances, by absorption, which damps out some destru

Dinesh Kumar Srivastava

The production of single photons in relativistic heavy ion collisions at CERN SPS, BNL RHIC and CERN LHC energies is re-examined in view of the recent studies of Aurenche et al which show that the rate of photon production from quark gluon plasma, evaluated at the order of two loops far exceeds the rates evaluated at one-loop level which have formed the basi

Emile Hoskinson, Zhen Ye

Acoustic wave propagation in liquid media containing many parallel air-filled cylinders is considered. A self-consistent method is used to compute rigorously the propagation, incorporating all orders of multiple scattering. It is shown that under proper conditions, multiple scattering leads to a peculiar phase transition in acoustic propagation. When the pha

V. Yu. Irkhin, M. I. Katsnelson

A scaling consideration of the Kondo lattices is performed with account of singularities in the spin excitation spectral function. It is shown that a non-Fermi-liquid (NFL) behavior between two critical values of the bare $s-f$ coupling constant occurs naturally for complicated magnetic structures with several magnon branches. This may explain the fact that

Damien Challet, Matteo Marsili

We show that the Minority Game, a model of interacting heterogeneous agents, can be described as a spin systems and it displays a phase transition between a symmetric phase and a symmetry broken phase where the games outcome is predicable. As a result a ``spontaneous magnetization&#39;&#39; arises in the spin formalism.

Stanislaw D. Glazek

We apply a boost-invariant similarity renormalization group procedure to a light-front Hamiltonian of a scalar field phi of bare mass mu and interaction term g phi^3 in 6 dimensions using 3rd order perturbative expansion in powers of the coupling constant g. The initial Hamiltonian is regulated using momentum dependent factors that approach 1 when a cutoff p

K. B. Blyuss

This paper considers properties of nonlinear waves and solitons of Korteweg-de Vries equation in the presence of external perturbation. For time-periodic hamiltonian perturbation the width of the stochastic layer is calculated. The conclusions about chaotic behaviour in long-period waves and solitons are inferred. Obtained theoretical results find experiment

Q-Han Park, H. J. Shin

Using the Painlevé analysis, we investigate the integrability properties of a system of two coupled nonlinear Schrödinger equations that describe the propagation of orthogonally polarized optical waves in an isotropic medium. Besides the well-known integrable vector nonlinear Schrödinger equation, we show that there exist a new set of equations passing the P

Jongbae Kim, Q-Han Park, H. J. Shin

Conservation laws of the nonlinear Schrödinger equation are studied in the presence of higher-order nonlinear optical effects including the third-order dispersion and the self-steepening. In a context of group theory, we derive a general expression for infinitely many conserved currents and charges of the coupled higher-order nonlinear Schrödinger equation.

Q-Han Park, H. J. Shin

It is shown that the McCall-Hahn theory of self-induced transparency in coherent optical pulse propagation can be identified with the complex sine-Gordon theory in the sharp line limit. We reformulate the theory in terms of the deformed gauged Wess-Zumino-Witten sigma model and address various new aspects of self-induced transparency.

P. Facchi, S. Pascazio

The deviations from a purely exponential behavior in a decay process are analyzed in relation to Van Hove&#39;s &#34;λ^2 t&#34; limiting procedure. Our attention is focused on the effects that arise when the coupling constant is small but nonvanishing. We first consider a simple model (two-level atom in interaction with the electromagnetic field), then gradu

Juan F. Poyatos, Gonzalo Garcia de Polavieja

A procedure to enhance the quantum--classical correspondence even in situations far from the classical limit is proposed. It is based on controlling the quantum transport between classical regions using the capability to synthesize arbitrary motional states in ion traps. Quantum barriers and passages to transport can be created selecting the relevant frequen

S. Scheel, L. Knoll, D. G. Welsch

Starting from the quantized version of Maxwell&#39;s equations for the electromagnetic field in an arbitrary linear Kramers-Kronig dielectric, spontaneous decay of the excited state of a two-level atom embedded in a dispersive and absorbing medium is studied and the decay rate is calculated. The calculations are performed for both the (Clausius-Mosotti) virt

C. Cheshkov, G. Georgiev, E. Gouchtchine, L. Litov

The application of reach-through avalanche photodiodes (R&#39;APD) as a photodetector for scintillator tiles has been investigated. The light collected by WLS fibers (0.84mm and 1mm diameter) embedded in the scintillator has been transmited to the 0.5mm2 active surface of APD by clear optical fibers and optical connectors. A low noise charge sensitive preamp

M. Akatsu, M. Aoki, K. Fujimoto, Y. Higashino

We describe here a new concept of a Cherenkov detector for particle identification by means of measuring the Time-of-Propagation (TOP) of Cherenkov photons.

Zhen Ye, Haoran Hsu, Emile Hoskinson, Alberto Alvarez

The paper presents a discussion on localization of acoustic waves. Some important questions about wave localization are addressed. Particular attention is paid to acoustic localization in liquid media containing many air-filled bubbles. It is shown that an amazing collective behavior appears when localization occurs. The study sheds new light to the much dis

Valeri Kapin

The normal mode theory of the transmission lines is applied to the studies of the Four-Rod RFQ. This resonator consists of four quadrupole electrodes and stems. It can be simulated by the four-conductor shielded transmission line, which is loaded by sets of coaxial transmission lines corresponding to the support stems. The ideal case of the indefinite period

L. E. Guerrero, A. Bellorin, J. R. Carbo, J. A. Gonzalez

We present an analytical and numerical study of the Klein-Gordon kink-soliton dynamics in inhomogeneous media. In particular, we study an external field that is almost constant for the whole system but that changes its sign at the center of coordinates and a localized impurity with finite-width. The soliton solution of the Klein-Gordon-like equations is usua

Andrey A. Sukhorukov, Nail N. Akhmediev

We analyze photo-refractive incoherent soliton beams and their interactions in Kerr-like nonlinear media. The field in each of M incoherently interacting components is calculated using an integrable set of coupled nonlinear Schrodinger equations. In particular, we obtain a general N-soliton solution, describing propagation of multi-soliton complexes and thei

Bao-An Li, C. M. Ko, Andrew T. Sustich, Bin Zhang

Within a relativistic transport (ART) model for heavy-ion collisions, we show that the recently observed characteristic change from out-of-plane to in-plane elliptic flow of protons in mid-central Au+Au collisions as the incident energy increases is consistent with the calculated results using a stiff nuclear equation of state (K=380 MeV). We have also studi

Jan Ryckebusch, Dimitri Debruyne, Wim Van Nespen, Stijn Janssen

The effect of meson and isobar degrees of freedom in A($\vec{e},e&#39;\vec{p}$) and A(e,e&#39;n) is studied for four-momentum transfers Q^2 in the range between 0.2 and 0.8 (GeV/c)^2. The calculations are performed in a non-relativistic framework with explicit (N,Δ,π) degrees-of-freedom. For the whole range of momentum transfers under investigation the relat

M. Farine, P. Schuck

Surface properties of neutron-neutron (T=1) pairing in semi-infinite nuclear matter in a hard wall potential are investigated in BCS approximation using the Gogny force. Surface enhancement of the gap function, pairing tensor and correlation energy density is put into evidence.

Michael Duren

This letter claims that process of stimulated emission of radiation can be used to induce a fusion reaction in a HD molecule to produce Helium-3. An experimental set-up for this reaction is presented. It is proposed to study the technical potential of this reaction as an energy amplifier.

P. P. Divakaran

It is shown that the quantum mechanics of a charged particle moving in a uniform magnetic field in the plane (Landau) or on a planar lattice (Peierls) is described in all detail by the projective representation theory of the &#34;euclidean&#34; group of the appropriate configuration space. In the Landau case, a detailed description of the state space as well

Gaetano Fiore, John Madore

A detailed study is made of the noncommutative geometry of $R^3_q$, the quantum space covariant under the quantum group $SO_q(3)$. For each of its two $SO_q(3)$-covariant differential calculi we find its metric, the corresponding frame and two torsion-free covariant derivatives that are metric compatible up to a conformal factor and which yield both a vanish

V. D. Lyakhovsky, D. N. Ananikian

The existence of dual structures in a Yangian Y(g) signify that the latter belongs to multidimensional naturally parametrized variety of Hopf algebras. These varieties have boundaries containing Yangians Y(a) inequivalent to the original Y(g). The new basic algebra $a$ is an algebra of the cotangent bundle attributed to the dual structure. We show how to con

Nandor Sieben

Primitive equivalence of graphs and matrices was used by Enomoto, Fujii and Watatani to classify Cuntz-Krieger algebras of 3x3 irreducible matrices. In this paper it is shown that the definition of primitive equivalence can be simplified using primitive transfers of matrices that involve only two rows of the matrix.

Jochen Brüning, Matthias Lesch

The purpose of this note is to describe a unified approach to the fundamental results in the spectral theory of boundary value problems, restricted to the case of Dirac type operators. Even though many facts are known and well presented in the literature (cf. the monograph of Booss-Wojciechowski), we simplify and extend or sharpen most results by using syste

Ezra Getzler

The Virasoro conjecture is a conjectured sequence of relations among the descendent Gromov-Witten invariants of a smooth projective variety in all genera; the only varieties for which it is known to hold are a point (Kontsevich) and Calabi-Yau threefolds (S. Katz). We review the statement of the conjecture and its proof in genus 0, following Eguchi, Hori and

M. Goussarov, M. Polyak, O. Viro

We observe that any knot invariant extends to virtual knots. The isotopy classification problem for virtual knots is reduced to an algebraic problem formulated in terms of an algebra of arrow diagrams. We introduce a new notion of finite type invariant and show that the restriction of any such invariant of degree n to classical knots is an invariant of degre

Matthias Lesch, Mark M. Malamud

On the half line $[0,\infty)$ we study first order differential operators of the form $B 1/i d/(dx) + Q(x)$, where $B:=\mat{B_1}{0}{0}{-B_2}$, $B_1,B_2\in M(n,\C)$ are self--adjoint positive definite matrices and $Q:\R_+\to M(2n,\C)$, $\R_+:=[0,\infty)$, is a continuous self-adjoint off-diagonal matrix function. We determine the self-adjoint boundary conditi

Elso Drigo Filho, Regina Maria Ricotta

The restricted class of Natanzon potentials with two free parameters is studied within the context of Supersymmetric Quantum Mechanics. The hierarchy of Hamiltonians is indicated, where the first members of the superfamily are explicitly evaluated and a general form for the superpotential is proposed.

J. -M. Chung

We show that in the functional integral formalism the (finite) coefficient of the induced, Lorentz- and CPT-violating Chern-Simons term, arising from the Lorentz- and CPT-violating fermion sector, is undetermined.

N. Itzhaki

We propose a field theory argument, which rests on the non-renormalization of the two point function of the energy-momentum tensor, why the ratio between the entropies of strongly coupled and weakly coupled N=4 is of order one.

Michael Haack, Boris Kors, Dieter Lust

These lectures intend to give a pedagogical introduction into some of the developments in string theory during the last years. They include perturbative T-duality and non perturbative S- and U-dualities, their unavoidable demand for D-branes, an example of enhanced gauge symmetry at fixed points of the T-duality group, a review of classical solitonic solutio

Sze-Shiang Feng, Dong-Pei Zhu

We exactly calculated the parity-odd term of the effective action induced by the fermions in 2+1 dimensions at finite chemical potential and finite temperature. It shows that gauge invariance is still respected. A more gerneral class of background configurations is considered. The knowledge of the reduced 1+1 determinant is required in order to draw exact co

Mauricio Contreras, Jorge Zanelli

The formulation of gravity in 3+1 dimensions in which the spin connection is the basic field ($ω$-frame) leads to a theory with first and second class constraints. Here, the Dirac brackets for the second class constraints are evaluated and the Dirac algebra of first class constraints is found to be the usual algebra associated to space-time reparametrization

R. Casalbuoni, A. Deandrea, S. De Curtis, D. Dominici

We explore an alternative to the usual procedure of scanning for determining the properties of a narrow $s$-channel resonance. By varying the beam energy resolution while sitting on the resonance peak, the width and branching ratios of the resonance can be determined. The statistical accuracy achieved is superior to that of the usual scan procedure in the ca

G. L. Fogli, E. Lisi, A. Marrone, G. Scioscia

The atmospheric neutrino data collected by the Super-Kamiokande experiment span about four decades in neutrino energy E, and are thus appropriate to probe the energy dependence of the oscillation wavelength λassociated to nu_mu<--->nu_tau flavor transitions, when these are assumed to explain the data. Such dependence takes the form λ^{-1}\propto E^n in a wid

Alessandro Strumia

After presenting a simple procedure for testing naturalness (similar to Bayesian inference and not more subjective than it) we show that LEP2 experiments pose a naturalness problem for `conventional&#39; supersymmetric models. About 95% of the parameter space of minimal supergravity MSSM is excluded by LEP2 experiments. Moreover in this model electroweak bar

Carlo Ewerz, Bryan R. Webber

We present predictions of jet rates in deep inelastic scattering at small x to leading-logarithmic order in x, including all sub-leading logarithms of Q^2/m_R^2 where m_R is the transverse momentum scale at which jets are resolved. We give explicit results for up to three jets, and a perturbative expansion for multi-jet rates and jet multiplicities.

Thomas Teubner

In this contribution I review the physics of top quarks at a future Linear Collider. Main emphasis is put on the process e+ e- to ttbar close to threshold. Different physical observables, their sensitivity to the basic parameters and their theoretical prediction are discussed. Recent higher order calculations are shown to have a considerable impact on a prec

Maria-Teresa Dova, Pablo Lacentre, John Swain, Lucas Taylor

We analyse the process $τ^-\toν_τπ^-π^0$ allowing for anomalous weak charged current magnetic and electric dipole moment interactions and determine the effects on the differential and total decay rates. Using recent experimental data we determine the following values for the anomalous magnetic and electric dipole moment parameters, respectively: $κ= 0.16 \pm