May 1998 arXiv papers — page 19

A. L. Kataev

We reminde definite results related to the low-energy hadronic phenomenology, obtained using the QCD sum rules methods. We emphasize that these results can be of interest for the comparison with available and new experimental results, obtained in part by the experimentalists of IHEP (Protvino).

Michael Melles

A physically defined effective charge can incorporate quark masses analytically at the flavor thresholds. Therefore, no matching conditions are required for the evolution of the strong coupling constant through these thresholds. In this paper, we calculate the massive fermionic corrections to the heavy quark potential through two loops. The calculation uses

C. B. Yang, X. Cai

Multiplicity distribution in small bins is studied within the Ginzburg-Landau description for first-order quark-hadron phase transition. Direct comparison of the distribution with a Poisson one (with the same average) is made. Dynamical factor $d_q$ for the distributionand ratio $D_q\equiv d_q/d_1$ are studied, and novel scaling behaviors between $D_q$ are f

C. S. Lam

An attempt is made in QCD to explain the growth of total cross-sections with energy, without violating the Froissart bound. This is achieved by computing the phase shifts of elastic scatterings of partons rather than their amplitudes. To render that possible a general formalism of phase-shifts in QCD is developed. Computed to two-loop order, agreements with

Michael Chavel

Lattice QCD with additional chiral-invariant four-fermion interactions is studied at nonzero temperature. Staggered Kogut-Susskind quarks are used. The four-fermion interactions are implemented by introducing bosonic auxiliary fields. A mean field treatment of the auxiliary fields is used to calculate the model's asymptotic scale parameter and perturbati

A. V. Minkevich, A. S. Garkun

Geometrical structure of homogeneous isotropic models in the frame of the metric-affine gauge theory of gravity (MAGT) is analyzed. By using general form of gravitational Lagrangian including both a scalar curvature and various invariants quadratic in the curvature, torsion and nonmetricity tensors, gravitational equations of MAGT for homogeneous isotropic m

D. G. Barci, E. V. Correa Silva, J. F. Medeiros Neto

We analyze the electromagnetic response of a system of charged bosons coupled to a Chern-Simons gauge field. Path integral techniques are used to obtain an effective action for the particle density of the system dressed with quantum fluctuations of the CS gauge field. From the action thus obtained we compute the U(1) current of the theory for an arbitrary el

D. Cule, S. Torquato

Spatial fluctuations of the local electric field induced by a constant applied electric field in composite media are studied analytically and numerically. It is found that the density of states for the fields exhibit sharp peaks and abrupt changes in the slope at certain critical points which are analogous to van Hove singularities in the density of states f

S. A. Larin, M. Moennigmann, M. Stroesser, V. Dohm

We present an analytic five-loop calculation for the additive renormalization constant A(u,ε) and the associated renormalization-group function B(u) of the specific heat of the O(n) symmetric ϕ^4 theory within the minimal subtraction scheme. We show that this calculation does not require new five-loop integrations but can be performed on the basis of the pre

Yu. Dimashko, C. Morais Smith

We study the transversal dynamics of a charged stripe (quantum string) at $T = 0$ and show that its kink excitations play the role of current carriers. If the hopping amplitude $t$ is much smaller than the string tension $J$, the string is pinned and its ground state (GS) is insulating. At $t \gg J$, the string is depinned and the GS is a kink-condensate. By

M. -A. Lewis, P. Simon

We investigate the renormalization group flows and fixed point structure of many coupled minimal models. The models are coupled two by two by energy-energy couplings. We take the general approach where the bare couplings are all taken to be independent. New fixed points are found for N models (N>3). At these fixed points, the coupling constants all have the

Jiri Maly, Boldizsar Janko, K. Levin

We investigate the pseudogap onset temperature $T^*$, the superconducting transition temperature $T_c$ and the general nature of the pseudogap phase using a diagrammatic BCS-Bose Einstein crossover theory. This decoupling scheme is based on the pairing approximation of Kadanoff and Martin, further extended by Patton (KMP). Our consideration of the KMP pairin

Robert V. Wagoner

We will summarize results of calculations of the modes of oscillation trapped within the inner region of accretion disks by the strong-field gravitational properties of a black hole (or a compact, weakly-magnetized neutron star). Their driving and damping will also be addressed. The focus will be on the most observable class: the analogue of internal gravity

Neil J. Cornish, Glenn D. Starkman

The case grows ever stronger that the average density of matter, ordinary and dark, is less than the critical density required for a flat universe. However, most of determinations of the mass density have been dynamical, hence sensitive only to matter which is clustered at or below the scale of the observed dynamical systems. The density may still be critica

Enrique Vazquez-Semadeni, Thierry Passot

We discuss HD and MHD compressible turbulence as a cloud-forming and cloud-structuring mechanism in the ISM. Results from a numerical model of the turbulent ISM at large scales suggest that the phase-like appearance of the medium, the typical values of the densities and magnetic field strengths in the intercloud medium, as well as the velocity dispersion-siz

Juri Poutanen

We discuss properties of thermal and hybrid (thermal/non-thermal) electron-positron plasmas in the pair and energy equilibria. Various accretion disc-corona models, recently proposed to explain properties of galactic as well as extragalactic accreting black holes, are confronted with the observed broad-band X-ray and gamma-ray spectra.

Massimo Della Valle, Markus Kissler-Patig, John Danziger, Jesper Storm

We have determined the absolute magnitude at maximum light of SN 1992A by using the turn-over magnitude of the Globular Cluster Luminosity Function of its parent galaxy, NGC 1380. A recalibration of the peak of the turn-over magnitude of the Milky Way clusters using the latest HIPPARCOS results has been made with an assessment of the complete random and syst

J. L. Han, R. Beck, E. M. Berkhuijsen

We observed 21 polarized background radio sources in the field of M31 at 1.365 GHz and 1.652 GHz, and determined their rotation measures (RMs). The RM data show that the regular magnetic field of the disk probably extends from about 5 kpc to 25 kpc from the center with similar structure. The RMs obtained from the polarized emission from M31 at $λ$6 cm and $λ

G. Weigelt, Y. Balega, T. Bloecker, A. J. Fleischer

We present the first K'-band image of the carbon star IRC+10216 with 76 mas resolution. The diffraction-limited image was reconstructed from 6m telescope speckle data using the speckle masking bispectrum method. The image shows that the dust shell of IRC+10216 is extremely clumpy. Five individual clouds within a 210 mas radius of the central star have be

Xing Li, Shadia Rifai Habbal, John Kohl, Giancarlo Noci

Recent observations of the spectral line profiles and intensity ratio of the O VI 1032 Å and 1037.6 Å doublet by the Ultraviolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory (SOHO), made in coronal holes below 3.5 $R_s$, provide evidence for Doppler dimming of the O VI 1037.6 Å line and pumping by the chromospheric C II 1037.0182

A. Baykal, J. H. Swank, M. J. Stark, T. E. Strohmayer

We present new X-ray observations of the X-ray pulsar 1E 2259+586, obtained during March 1997, with the Rossi X-Ray Timing Explorer (RXTE). We have measured the pulse frequency derivative $\dot ν= (-1.08 \pm 0.04) \times 10^{-14}$ Hz s$^{-1}$ from pulse arrival times obtained in a sequence of 5 observations spread over one month. This $\dotν$ is consistent w

Lina Tomasella, Ulisse Munari

The no-longer-eclipsing system SS Lac in the young open cluster NGC 7209 has been recently announced to show a constant radial velocity. Puzzled by this finding, we have monitored the system during 1997 obtaining 24 Echelle+CCD spectra over 8 orbital revolutions. Our spectra reveal a nice orbital motion with periodic splitting and merging of spectral lines f

Bing Chen, Jean Luc Vergely, Bernard Valette, Giovanni Carraro

Interstellar absorption in the galactic plane is highly variable from one direction to another. In this paper colour excesses and distances from a new open cluster sample are used to investigate the spatial distribution of the interstellar extinction. An inverse method (Tarantola & Valette, 1982) is used to construct the extinction map in the galactic plane

A. E. Gomez, X. Luri, V. Sabas, S. Grenier

The position in the HR diagram and the kinematic characteristics of different kinds of CP stars of the upper main sequence are obtained using the LM method (Luri et al., 1996). Most of the CP stars are main sequence stars occupying the whole width of the sequence. From a kinematic point of view, they belong to the young disk population (ages < 1.5 Gyr). It h

F. Figueras, X. Luri, A. E. Gomez, J. Torra

The application of the Stromgren photometric luminosity calibrations to different types of CP stars is reexamined in the light of the new Hipparcos data. A first attempt is made to use the LM statistical parallax method (Luri et al., 1996) -- based on the maximum likelihood principle -- to obtain a calibration of the absolute magnitude as a function of two S

W. Yuan, W. Brinkmann, J. Siebert, W. Voges

A database of radio-quiet quasars detected with ROSAT is presented containing 846 quasars seen in the All-Sky Survey and/or in pointed PSPC observations. About 70% of the objects have been detected in X-rays for the first time. We present the soft X-ray fluxes and spectra, if available. Using an optically selected subsample compiled from this database, we st

P. North, N. Ginestet, J. -M. Carquillat, F. Carrier

The results of long-term surveys of radial velocities of cool Ap and Am stars are presented. There are two samples, one of about 100 Ap stars and the other of 86 Am stars. Both have been observed with the CORAVEL scanner from Observatoire de Haute-Provence (CNRS), France. The conspicuous lack of short-period binaries among cool Ap stars seems confirmed, alth

G. A. Tammann

Four Hubble diagrams are combined to test for the linearity of the cosmic expansion field. The expansion rate, H_0, is found to decrease by ~5% out to 18000km/s. Beyond this distance the mean value of H_0 is close to the value at 10000km/s. The absolute value of H_0 is derived in two different ways. The one leads through Cepheids from HST and blue SNe Ia to

David Atwood, Amarjit Soni

We derive constraints for $B\to VV$ modes ($V= vector meson) that allow aquantitative assessment of the contributions from electroweak penguins (EWP) and/or new physics. Interplay of direct CP with oscillation studies then leads to the extraction of the angles alpha and gamma, using B--> K* omega rho and B--> rho omega (phi) respectively, if by using our con

Yosef Ashkenazy

An algorithm for calculating generalized fractal dimension of a time series using the general information function is presented. The algorithm is based on a strings sort technique and requires $O(N \log_2 N)$ computations. A rough estimate for the number of points needed for the fractal dimension calculation is given. The algorithm was tested on analytic exa

Doron Cohen

We analyze quantal Brownian motion in $d$ dimensions using the unified model for diffusion localization and dissipation, and Feynman-Vernon formalism. At high temperatures the propagator possess a Markovian property and we can write down an equivalent Master equation. Unlike the case of the Zwanzig-Caldeira-Leggett model, genuine quantum mechanical effects m

B. G. Sidharth

In the light of some recent results, it is argued that usual concepts of causality and locality are approximations valid at scales greater than the Compton wavelength and corresponding time scales. It follows that the &#34;spooky&#34; non-locality of Quantum Mechanics is not really so and infact is perfectly consistent with a recently discussed holistic mode

J. E. Avron

When time reversal is broken the viscosity tensor can have a non vanishing odd part. In two dimensions, and only then, such odd viscosity is compatible with isotropy. Elementary and basic features of odd viscosity are examined by considering solutions of the wave and Navier-Stokes equations for hypothetical fluids where the stress is dominated by odd viscosi

E. Friedman, A. Gal

The binding energies of the deeply bound 1s and 2p states in pionic atoms of $^{207}$Pb, recently established experimentally in the $^{208}$Pb(d,$^3$He) reaction, have been used by several groups to derive the pion effective mass in nuclear matter. We show that these binding energies are fully consistent with `normal&#39; pionic atoms and that the real part

Hans-Jürgen Glaeske, Anatoly A. Kilbas, Megumi Saigo, Sergei A. Shlapakov

Integral transforms $$(\mbox{\boldmath$H$}f)(x)=\int^\infty_0H^{m,n}_{\thinspace p,q} \left[xt\left|\begin{array}{c}(a_i,α_i)_{1,p}\\[1mm](b_j,β_j)_{1,q} \end{array}\right.\right]f(t)dt$$ involving Fox&#39;s $H$-functions as kernels are studied in the spaces $\Ls_{ν,r}$ of functions $f$ such that $$\int^\infty_0|t^νf(t)|^r\frac{dt}t<\infty\quad(1\ \eqls\ r<\

Gaspard Bangerezako

A special Infeld-Hall factorization is given for the Askey-Wilson second order q-difference operator. It is then shown how to deducd a generalization of the corresponding Askey-Wilson polynomials.

Gaspard Bangerezako

Darboux Transformation, well known in second order differential operator theory, is applied here to the difference equation satisfied by the discrete hypergeometric polynomials(Charlier, Meixner-Krawchuk, Hahn).

R. B. Zhang

Differential calculi are obtained for quantum homogeneous spaces by extending Woronowicz&#39; approach to the present context. Representation theoretical properties of the differential calculi are investigated. Connections on quantum homogeneous vector bundles are classified and explicitly constructed by using the theory of projective modules.

Martin Welk

We study covariant differential calculus on the quantum spheres S_q^2N-1. Two classification results for covariant first order differential calculi are proved. As an important step towards a description of the noncommutative geometry of the quantum spheres, a framework of covariant differential calculus is established, including a particular first order calc

C. S. Lam

I discuss a formula decomposing the integral of time-ordered products of operators into sums of products of integrals of time-ordered commutators. The resulting factorization enables summation of an infinite series to be carried out to yield an explicit formula for the time-ordered exponentials. The Campbell-Baker-Hausdorff formula and the nonabelian eikonal

Sung-Soo Kim, Phillial Oh

We examine classical and quantum aspects of the planar non-compact spin system coupled with Chern-Simons gauge field in the presence of background charge. We first define our classical spin system as non- relativistic non-linear sigma model in which the order parameter spin takes value in the non-compact manifold ${\cal M}=SU(1,1)/U(1)$. Although the naive m

M. F. Parry, A. T. Sornborger

We numerically investigate the decay, via parametric resonance, of the inflaton with an m^2 phi^2 potential into a scalar matter field with a symmetry breaking potential. We consider the case where symmetry breaking takes place during inflation. We show that when expansion is not taken into account symmetry restoration and non-thermal defect production durin

C. S. Lam

We consider the emission or absorption of $n$ identical bosons from an energetic or a massive particle, in which the bosons and the source particle are allowed to be offshell. The Bose-Einstein symmetrized amplitude can be decomposed into sums and products of more elementary objects which we choose to call `atoms&#39;. The origin of this decomposition, its s

O. V. Babourova, B. N. Frolov, E. A. Klimova

The definition of the Riemann-Cartan space of the plane wave type is given. The condition under which the torsion plane waves exist is found. It is expressed in the form of the restriction imposed on the coupling constants of the 10-parametric quadratic gravitational Lagrangian. In the mathematical appendix the formula for commutator of the variation operato

J. M. Carmona, J. Richert, A. Tarancon

We develop a model in the framework of nuclear fragmentation at thermodynamic equilibrium which can be mapped onto an Ising model with constant magnetization. We work out the thermodynamic properties of the model as well as the properties of the fragment size distributions. We show that two types of phase transitions can be found for high density systems. Th

Claudia Peça, Jose&#39; P. S. Lemos

The thermodynamical properties of the Reissner-Nordström-anti-de Sitter black hole in the grand canonical ensemble are investigated using York&#39;s formalism. The black hole is enclosed in a cavity with finite radius where the temperature and electrostatic potential are fixed. The boundary conditions allow us to compute the relevant thermodynamical quantiti

Semjon Stepanow, Jens-Uwe Sommer, Igor Ya. Erukhimovich

We consider adsorption of random copolymer chains onto an interface within the model of Garel et al. Europhysics Letters 8, 9 (1989). By using the replica method the adsorption of the copolymer at the interface is mapped onto the problem of finding the ground state of a quantum mechanical Hamiltonian. To study this ground state we introduce a novel variation

Sergio Conti, Tapash Chakraborty

We formulate a self-consistent field theory for the Chern-Simons fermions to study the dynamical response function of the quantum Hall system at $ν=1/2$. Our scheme includes the effect of correlations beyond the random-phase approximation (RPA) employed to this date for this system. The resulting zero-frequency density response function vanishes as the squar

V. V. Bazhanov, S. L. Lukyanov, A. B. Zamolodchikov

In this paper we fill some gaps in the arguments of our previous papers [hep-th/9412229,hep-th/9604044]. In particular, we give a proof that the L operators of Conformal Field Theory indeed satisfy the defining relations of the Yang-Baxter algebra. Among other results we present a derivation of the functional relations satisfied by ${\bf T}$ and ${\bf Q}$ op

Katsuhiko Yoshida, Satoru Saito

A coupled system of two generalized logistic maps is studied. In particular influence of the coupling to the behaviour of the Julia set in two dimensional complex space is analyzed both analytically and numerically. It is proved analytically that the Julia set disappears from the complex plane uniformly as a parameter interpolates from the chaotic phase to t

R. M. Cavalcanti

Using the Caldirola-Kanai Hamiltonian, we study the time evolution of the wave function of a particle whose classical motion is governed by the Langevin equation. We show, in particular, that if the initial wave function is Gaussian, then (i) it remains Gaussian for all times, (ii) its width grows, approaching a finite value when t->infinity, and (iii) its c

C. Brif, A. Mann, M. Revzen

We review classical properties of harmonic-oscillator coherent states. Then we discuss which of these classical properties are preserved under the group-theoretic generalization of coherent states. We prove that the generalized coherent states of quantum systems with Lie-group symmetries are the unique Bell states, i.e., the pure quantum states preserving th

Nikolai Gouliaev, John F. Nagle

Quantitative theory of interbilayer interactions is essential to interpret x-ray scattering data and to elucidate these interactions for biologically relevant systems. For this purpose Monte Carlo simulations have been performed to obtain pressure P and positional fluctuations sigma. A new method, called Fourier Monte-Carlo (FMC), that is based on a Fourier

A. V. Shapovalov, E. V. Evdokimov

We study the Fisher model describing natural selection in a population with a diploid structure of a genome by differential- geometric methods. For the selection dynamics we introduce an affine connection which is shown to be the projectively Euclidean and the equiaffine one. The selection dynamics is reformulated similar to the motion of an effective partic

Nikolai Gouliaev, John F. Nagle

The liquid crystalline model biomembrane system consisting of a stack of interacting membranes is studied by the newly developed Fourier Monte Carlo simulation technique. In comparison to perturbation theory, substantial quantitative discrepancies are found that affect determination of interbilayer interactions. A harmonic theory is also routinely used to in

V. D. Efros, W. Leidemann, G. Orlandini

The spectral function of 4He is calculated with the Lorentz integral transform method in a large energy and momentum range. The excitation spectrum of the residual 3N-system is fully taken into account. The obtained spectral function is used to calculate the quasi elastic longitudinal (e,e&#39;) response R_l of 4He for q=300, 400, and 500 MeV/c. Comparison w

Toshinori Oaku, Nobuki Takayama

We describe algorithms for computing various functors for algebraic D-modules, i.e. systems of linear partial differential equations with polynomial coefficients. We will give algorithms for restriction, tensor product, localization, and local cohomology groups for all degrees.

D. Markushevich, Yu. G. Prokhorov

We construct two examples of canonical exceptional singularities.

A. Nersessian

The Hamiltonian formulation for the mechanical systems with reparametrization-invariant Lagrangians, depending on the worldline external curvatures is given, which is based on the use of moving frame. A complete sets of constraints are found for the Lagrangians with quadratic dependence on curvatures, for the lagrangians, proportional to an arbitrary curvatu

Chi-Keung Chow, Soo-Jong Rey

Baryons of lower spin in partially quenched large-$N_c$ QCD are studied with particular emphasis to interpolation between standard unquenched and fully quenched limits. In large $N_c$ limit of partially quenched QCD, we calculate $Δm$, the chiral one-loop correction to baryon masses. We find that leading order contribution to $Δm$ is independent of number of

D. M. Stamper-Kurn, H. -J. Miesner, A. P. Chikkatur, S. Inouye

We present a method of adiabatically changing the local phase-space density of an ultracold gas, using a combination of magnetic and optical forces. Applying this method, we observe phase-space density increases in a gas of sodium atoms by as much as 50-fold. The transition to Bose-Einstein condensation was crossed reversibly, attaining condensate fractions

R. Roth, U. Schollwoeck

We investigate frustrated antiferromagnetic Heisenberg quantum spin chains at T=0 for S=3/2 and S=2 using the DMRG method. We localize disorder and Lifshitz points, confirming that quantum disorder points can be seen as quantum remnants of classical phase transitions. Both in the S=3/2 and the S=2 chain, we observe the disappearance of effectively free S=1/2

D. Vokrouhlicky, V. Karas

The long-term evolution of stellar orbits bound to a massive centre is studied in order to understand the cores of star clusters in central regions of galaxies. Stellar trajectories undergo tiny perturbation, the origin of which is twofold: (i) gravitational field of a thin gaseous disc surrounding the galactic centre, and (ii) cumulative drag due to success

Uros Seljak, Matias Zaldarriaga

We discuss statistical and physical properties of cosmic microwave background polarization, both in Fourier and in real space. The latter allows for a more intuitive understanding of some of the geometric signatures. We present expressions that relate electric and magnetic type of polarization to the measured Stokes parameters in real space and discuss how c

Isabelle Baraffe, Gilles Chabrier, France Allard, Peter Hauschildt

We present evolutionary models for low mass stars from 0.075 to 1 $\msol$ for solar-type metallicities [M/H]= 0 and -0.5. The calculations include the most recent interior physics and the latest generation of non-grey atmosphere models. We provide mass-age-color-magnitude relationships for both metallicities. The mass-M$_V$ and mass-M$_K$ relations are in ex

Michael Dine, Robert Echols, Joshua P. Gray

$M$-theory is believed to be described in various dimensions by large $N$ field theories. It has been further conjectured that at finite $N$, these theories describe the discrete light cone quantization (DLCQ) of $M$ theory. Even at low energies, this is not necessarily the same thing as the DLCQ of supergravity. It is believed that this is only the case for

P. O. Fedichev, G. V. Shlyapnikov

We develop a finite temperature perturbation theory (beyond the mean field) for a Bose-condensed gas and calculate temperature-dependent damping rates and energy shifts for Bogolyubov excitations of any energy. The theory is generalized for the case of excitations in a spatially inhomogeneous (trapped) Bose-condensed gas, where we emphasize the principal imp

Sonia Stanciu, Arkady Tseytlin

We find exact D-brane configurations in the Nappi-Witten background using the boundary state approach and describe how they are related by T-duality transformations. We also show that the classical boundary conditions of the associated sigma model correspond to a field dependent automorphism relating the chiral currents and discuss the correspondence between

Yuri V. Kovchegov, A. H. Mueller

We resum the recently calculated second order kernel of the BFKL equation. That kernel can be viewed as the sum of a conformally invariant part and a running coupling part. The conformally invariant part leads to a corrected BFKL intercept as found earlier. The running coupling part of the kernel leads to a non-Regge term in the energy dependence of high ene

Ken D. Olum

I investigate the relationship between faster-than-light travel and weak-energy-condition violation, i.e., negative energy densities. In a general spacetime it is difficult to define faster-than-light travel, and I give an example of a metric which appears to allow superluminal travel, but in fact is just flat space. To avoid such difficulties, I propose a d

S. J. van Enk, H. J. Kimble, J. I. Cirac, P. Zoller

We show that quantum information may be transferred between atoms in different locations by using ``phantom photons&#39;&#39;: the atoms are coupled through electromagnetic fields, but the corresponding field modes do not have to be fully populated. In the case where atoms are placed inside optical cavities, errors in quantum information processing due to ph

Peter Kopietz

We calculate the effect of Coulomb interactions on the average density of states nu (omega) of two-dimensional disordered electrons. It is shown that for weak disorder the most singular terms in the perturbative expansion of nu (omega) can be summed by means of a simple gauge transformation, which also establishes a relation between the low-frequency behavio

Lorenz Bartosch, Peter Kopietz

Using higher-dimensional bosonization, we study correlation functions of fermions with singular forward scattering. Following Bares and Wen [Phys. Rev. B 48, 8636 (1993)], we consider density-density interactions in d dimensions that diverge for small momentum transfers as q^{- eta} with eta = 2 (d-1). In this case the single-particle Green&#39;s function sh

G. Lopez Castro, J. H. Munoz, J. Pestieau

Unstable particles can be consistently described in the framework of quantum field theory. Starting from the full S-matrix amplitudes of B^+ --> (2 pi, 3 pi) l nu decays as examples in the energy region where the rho-omega resonances are dominating, we propose a prescription for the mixing of two quasi `physical&#39; unstable states that differs from the one

R. Fedele, V. I. Man&#39;ko

It is shown that charged-particle beam transport in the paraxial approximation can be effectively described with a quantum-like picture in semiclassical approximation. In particular, the classical Liouville equation can be suitably replaced by a von Neuman-like equation. Relevant remarks concerning the standard classical description of the beam transport are

N. Linden, S. Massar, S. Popescu

Known entanglement purification protocols for mixed states use collective measurements on several copies of the state in order to increase the entanglement of some of them. We address the question of whether it is possible to purify the entanglement of a state by processing each copy separately. While this is possible for pure states, we show that this is im

Andrew E. Chubykalo, Stoyan J. Vlaev

In the Comment [Eur. J. Phys., to be published] on our paper [Eur. J. Phys. 19 (1998) 1-6], the author declares that we claim that the ratio of inertial mass to gravitational mass can be derived ex nihilo and that our paper was published &#34;by mistake&#34;. In this &#34;Reply&#34; we dispute the point of view of the author.

M. Avrigeanu, V. Avrigeanu

The main formalisms of partial level densities (PLD) used in preequilibrium nuclear reaction models, based on the equidistant spacing model (ESM), are considered. A collection of FORTRAN77 functions for PLD calculation by using 14 formalisms for the related partial-state densities is provided and 28 sample cases (73 versions) are described. The results are g

Lu Lin

A time-decaying Dirac equation is suggested. For a free particle with rest mass about 0.5GeV, the live-time is about 10**(-25) second in the rest frame.

C. G. Bao

The inherent nodal structures of the wavefunctions of 4-nucleon systems have been investigated. The quantum numbers of the excited states (resonances) have been deduced. It was found that all the T=0 even-parity resonances are dominated by {2,1,1} component with L=1, all the T=0 odd-parity resonances are dominated by {3,1} component with L=1, and all the T=1

Kota Yoshioka

Recently, Minahan, Nemeschansky, Vafa and Warner computed partition functions for N=4 topological Yang-Mills theory on rational elliptic surfaces. In particular they computed generating functions of Euler characteristics of SU(2)-instanton moduli spaces. In mathematics, they are expected to coincide with those of Gieseker compactifications. In this paper, we

Alexander Dvorsky, Siddhartha Sahi

In this paper we consider the problem of decomposing tensor products of certain singular unitary representations of a semisimple Lie group G. Using explicit models for these representations (constructed earlier by one of us) we show that the decomposition is controlled by a reductive homogeneous space G&#39;/H&#39;. Our procedure establishes a correspondence

T. Barreiro, B. de Carlos, E. J. Copeland

We address the important issue of stabilizing the dilaton in the context of superstring cosmology. Scalar potentials which arise out of gaugino condensates in string models are generally exponential in nature. In a cosmological setting this allows for the existence of quasi scaling solutions, in which the energy density of the scalar field can, for a period,

Jian-Miin Liu

Besides the two fundamental postulates, (i) the principle of relativity and (ii) the constancy of the one-way velocity of light in all inertial frames of reference, the special theory of relativity employs another assumption. This assumption concerns the flat structures of gravity-free space and time in the usual inertial coordinate system. We introduce the

Jian-Miin Liu

Keeping the two fundamental postulates of the special theory of relativity, the principle of relativity and the constancy of the one-way velocity of light in all inertial frames of reference, and assuming two generalized Finslerian structures of gravity-free space and time in the usual inertial coordinate system, we can modify the special theory of relativit

João D. Correia

The instability of Liouville theory coupled to $c>1$ matter fields is shown to persist even when the ``spikes&#39;&#39; which represent highly singular geometries are allowed to interact in a natural way.

Pietro Menotti, Giuseppe Policastro

We compute the super Liouville action for a two dimensional Regge surface by exploiting the invariance of the theory under the superconformal group for sphere topology and under the supermodular group for torus topology. For sphere topology and torus topology with even spin structures, the action is completely fixed up to a term which in the continuum limit

A. A. Pankov, N. Paver

Fermion compositeness, and other types of new physics that can be described by the exchange of very massive particles, can manifest themselves as the result of an effective four-fermion contact interaction. In the case of the processes $e^+e^-\to μ^+μ^-,τ^+τ^-,\bar{b}b$ and $\bar{c}c$ at future $e^+e^-$ colliders with $\sqrt{s}=0.5-1$ TeV, we examine the sen

B. E. Cox, J. R. Forshaw

Diffractive scattering in the presence of a large momentum transfer is an ideal place to study the short distance rapidity gap producing mechanism. Previous studies (experimental and theoretical) in this area have focussed on gaps between jets and on high-$t$ vector meson production. We propose the measurement of double dissociation at high-$t$. We examine t

R. G Roberts

We present a new analysis of parton distributions of the proton. This incorporates a wide range of new data, an improved treatment of heavy flavours and a re-examination of prompt photon production. The new set (MRST) shows systematic differences from previous sets of partons which can be identified with particular features of the new data and with improveme

Takaaki Nagano, Masahiro Yamaguchi

Many models possess unwanted relics, which should be diluted by entropy production just before the big-bang nucleosynthesis. A field responsible for the entropy production may produce stable weakly interacting massive particles, if kinematically accessible. We compute their relic abundances by integrating out coupled equations numerically. Applying our resul

Mayumi Aoki

A decay rate asymmetry of the top quark is discussed within the framework of the supersymmetric standard model. Although new sources of CP violation in this model are severely constrained from the electric dipole moments of the neutron and the electron, there is a possibility that a top squark has a mass of around 100 GeV and CP violation in its interaction

C. T. H. Davies, I. M. Barbour, K. C. Bowler, R. D. Kenway

We give here the contents pages for the Proceedings of the Lattice &#39;97 conference (15th International Symposium on Lattice Field Theory) that took place in July 1997 in Edinburgh, Scotland. The contents are in html form with clickable links to the papers that exist on the hep-lat archive. We hope that this will make it easier to access the output of the

Y. Asaoka, K. Abe, K. Yoshimura, M. Ishino

This paper describes the development of a threshold type aerogel Cherenkov counter with a large sensitive area of 0.6 m$^2$ to be carried onboard the BESS rigidity spectrometer to detect cosmic-ray antiprotons. The design incorporates a large diffusion box containing 46 finemesh photomultipliers, with special attention being paid to achieving good performanc

Metin Gurses

Einstein&#39;s field equations are solved exactly for static charged dust distributions. These solutions generalize the Majumdar Papapetrou metrics. Maxwell&#39;s equations lead to the equality of charge and mass densities of the dust distribution. Einstein&#39;s equatins reduce to a nonlinear version of Poisson&#39;s equation.

Motomu Tsuda, Takeshi Shirafuji

We construct N = 2 chiral supergravity (SUGRA) which leads to Ashtekar&#39;s canonical formulation. The supersymmetry (SUSY) transformation parameters are not constrained at all and auxiliary fields are not required in contrast with the method of the two-form gravity. We also show that our formulation is compatible with the reality condition, and that its re

William Krivan, Richard H. Price

A technical flaw was found in this paper, and it has been withdrawn. It is intended that a modified version will be submitted soon.

J. Fürnkranz

In this paper we re-investigate windowing for rule learning algorithms. We show that, contrary to previous results for decision tree learning, windowing can in fact achieve significant run-time gains in noise-free domains and explain the different behavior of rule learning algorithms by the fact that they learn each rule independently. The main contribution

S. Grillo, H. Montani

We study a suitable q-deformed version of the Moriya&#39;s superexchange interaction theory by means of its underlying quantum group structure. We show that the one-dimensional chain case is associated with the non-standard quantum group $GL_{pq}(2) $, evidencing the integrability structure of the system. This biparametric deformation of $GL(2,{\bf C}) $ ari

Liang-Xin Li, Yia-Chung Chang

Band structures and optical matrix elements of strained multiple quantum-wires (QWR&#39;s) are investigated theoretically via the effective bond-orbital model, which takes into account the effects of valence-band anisotropy and the band mixing. In particular, the Ga$_{1-x}$In$_x$As QWR&#39;s grown by strain-induced lateral ordering (SILO) are considered. Rec