October 2000 arXiv papers — page 12

R. Arnowitt, B. Dutta, Y. Santoso

We consider neutralino-proton cross sections for halo dark matter neutralinos within the framework of supergravity models with R-parity invariance for models with universal soft breaking (mSUGRA) and models with nonuniversal soft breaking. The analysis includes the necessary corrections to treat the large tanbeta region (i.e. L-R mixing in the squark and sle

M. van Iersel, C. F. M. van der Burgh, B. L. G. Bakker

We have used different methods to obtain the bound states of a Hamiltonian of a relativistic two scalar particle system in a local potential. The potentials we are interested in are binding and confining potentials, that are associated with particle exchange. The issues we concentrate on when comparing the different methods are ease of numerical implementati

M. Ripani, V. Mokeev, M. Anghinolfi, M. Battaglieri

We acknowledge a paper on the same subject by other authors, that we didn't have the chance to cite in our work. A few comments on the content of the two papers are made.

Michael Gronau, Jonathan L. Rosner

A density-matrix method for the study of tagged states of neutral B mesons with arbitrary coherence properties is applied to several examples, including $e^+ e^-$ production both at and above the $Υ(4S)$ resonance, and hadronic production. In the absence of coherence the only term modulating the exponential decay of a neutral B meson behaves as $\cos Δm t$,

G. S. Sharov

The relativistic string with massive ends (the meson model) and four various string baryon models: q-qq, q-q-q, Y and $Δ$ are considered. In particular, the rotational motions for all these systems are applied to describing the leading Regge trajectories, and also the classical dynamics beyond the usual rectilinear string rotations is studied. For the string

Shinya Kanemura, Takashi Kasai, Guey-Lin Lin, Yasuhiro Okada

The current atmospheric and solar neutrino experimental data favors the bi-maximal mixing solution of the Zee-type neutrino mass matrix in which neutrino masses are generated radiatively. This model requires the existence of a weak singlet charged Higgs boson. While low energy data are unlikely to further constrain the parameters of this model, the direct se

T. Hattori, T. Hasuike, S. Wakaizumi

We investigate the neutrino oscillations of ν_μbeam at the K2K experiment in the four-neutrino model with three active and one sterile neutrinos, and compare them with the oscillations in the three-neutrino model. In the four-neutrino case, the effect of the Δm^2_{LSND} scale of mass-squared difference, derived from the LSND experiments, occurs in the surviv

Nils A. Tornqvist

This report summarizes the most important results presented at the recent conference held at the Yukawa Institute of Theoretical Physics in Kyoto, devoted to the recently confirmed light sigma resonance. Remarkably, all speakers at this meeting took the light sigma for granted and many mass and width estimations near 500 MeV were presented. We emphasize that

S. -Y. Wang, D. Boyanovsky, H. J. de Vega, D. -S. Lee

We study the real-time nonequilibrium dynamics in hot QED plasmas implementing a dynamical renormalization group and using the hard thermal loop (HTL) approximation. The focus is on the study of the relaxation of gauge and fermionic mean fields and on the quantum kinetics of the photon and fermion distribution functions. For semihard photons of momentum eT <

Shailesh Chandrasekharan, James C. Osborn

A new meron cluster algorithm is constructed to study the finite temperature critical behavior of the chiral condensate in a $(3+1)$ dimensional model of interacting staggered fermions. Using finite size scaling analysis the infinite volume condensate is shown to be consistent with the behavior of the form $(T_c-T)^{0.314(7)}$ for temperatures less than the

P. Cea, L. Cosmai

We investigate Abelian monopoles and Abelian vortices condensation in finite temperature SU(2) and SU(3) pure lattice gauge theories.

S. Hauswirth

The application of Renormalization Group (RG) methods to find perfect discretizations of partial differential equations is a promising but little investigated approach. We calculate the classically perfect fixed-point Laplace operator for boundaries of non-trivial shape analytically and numerically and present a parametrization that can be used for solving t

NA52 collaboration, R. Arsenescu, C. Baglin, H. P. Beck

The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark-gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating (&#39;wounded&#39;) nucleons N, above N=100. Previou

J. -F. Pascual-Sánchez

In this work, I present a generalized linear Hubble law for a barotropic spherically symmetric inhomogeneous spacetime, which is in principle compatible with the acceleration of the cosmic expansion obtained as a result of high redshift Supernovae data. The new Hubble function, defined by this law, has two additional terms besides an expansion one, similar t

J. -F. Pascual-Sánchez

It has been asserted in the literature that the analogy between the linear and first order slow motion approximation of Einstein equations of General Relativity (gravitomagnetic equations) and the Maxwell-Lorentz equations of electrodynamics breaks down if the gravitational potentials are time dependent. In this work, we show that this assertion is not corre

Ion I. Cotăescu, Ion I. Cotăescu, jr

We study the supersymmetry of the radial problems of the models of quantum relativistic rotating oscillators in arbitrary dimensions, defined as Klein-Gordon fields in backgrounds with deformed anti-de Sitter metrics. It is pointed out that the shape invariance of the supersymmetric partner radial potentials leads to simple operators forms of the Rodrigues f

James E. Lidsey, P. Vargas Moniz

In this paper we show that the spatially homogeneous Bianchi type I and Kantowski-Sachs cosmologies derived from the Brans-Dicke theory of gravity admit a supersymmetric extension at the quantum level. Global symmetries in the effective one-dimensional actions characterize both classical and quantum solutions. A wide family of exact wavefunctions satisfying

Kathrin Fuchss, Suhan Ree, L. E. Reichl

We examine a two-dimensional electron waveguide with a cut-circle cavity and conical leads. By considering Wigner delay times and the Landauer-Büttiker conductance for this system, we probe the effects of the closed billiard energy spectrum on scattering properties in the limit of weakly coupled leads. We investigate how lead placement and cavity shape affec

Gabriel Kotliar, Sergej Y. Savrasov, Gunnar Palsson

We propose a cellular version of dynamical-mean field theory which gives a natural generalization of its original single-site construction and is formulated in different sets of variables. We show how non-orthogonality of the tight-binding basis sets enters the problem and prove that the resulting equations lead to manifestly causal self energies.

M. Mueller, K. Binder

Using extensive Monte Carlo simulations we study the phase diagram of a symmetric binary (AB) polymer blend confined into a thin film as a function of the film thickness D. The monomer-wall interactions are short ranged and antisymmetric, i.e, the left wall attracts the A-component of the mixture with the same strength as the right wall the B-component, and

Wonkee Kim, J. P. Carbotte

In layered cuprates, the application of an in-plane magnetic field $({\bf H})$ changes the c-axis optical sum rule and superfluid density $ρ_{s}$. For pure incoherent c-axis coupling, ${\bf H}$ has no effect on either quantities but it does if an additional coherent component is present. For the coherent contribution, different characteristic variations on $

S. Lapinskas, E. E. Tornau, A. Rosengren

We have shown that the lattice-gas model with four repulsive pair interaction constants (corresponding to the four nearest coordination shells) on a simple cubic lattice is a sufficient model to describe the main types of cation ordering in relaxors. The phase diagram, obtained by the cluster variation method, shows the sequences of transitions between the p

K. S. D. Beach, R. J. Gooding, F. Marsiglio

We propose a fully microscopic theory of the anomalous normal state of the attractive Hubbard model in the low-density limit that accounts for propagator renormalization. Our analytical conclusions, which focus on the thermodynamic instabilities contained in the self-consistent equations associated with our formulation, have been verified by our comprehensiv

Shu-Chiuan Chang

The zero-temperature $q$-state Potts model partition function for a lattice strip of fixed width $L_y$ and arbitrary length $L_x$ has the form $P(G,q)=\sum_{j=1}^{N_{G,λ}}c_{G,j}(λ_{G,j})^{L_x}$, and is equivalent to the chromatic polynomial for this graph. We present exact zero-temperature partition functions for strips of several lattices with $(FBC_y,PBC_

Colin Denniston, Enzo Orlandini, J. M. Yeomans

We describe a lattice Boltzmann algorithm to simulate liquid crystal hydrodynamics. The equations of motion are written in terms of a tensor order parameter. This allows both the isotropic and the nematic phases to be considered. Backflow effects and the hydrodynamics of topological defects are naturally included in the simulations, as are viscoelastic prope

Sergio A. Cannas, Daniel A. Stariolo, Francisco A. Tamarit

We solve the Langevin dynamics of d-dimensional ferromagnetic spherical models with interactions that decay with distance as r^-(d+sigma). The long time dynamics of correlations and responses are studied in the different dynamical regimes and the validity of fluctuation-dissipation relations (or its violation) are shown. In particular, we show that the fluct

Dorina Andru Vangheli, Gheorghe Ardelean

In this paper, we present the possibility of using the Ising like models to explain by Statistical Physics means the connection between the financial discontinuities (herd behavior, bubbles, crashes) and &#34;critical points&#34; in physical of phase transitions due to cooperative effects. For this purpose there are investigated 1/2 and 3/2 Ising like spin m

Romualdo Pastor-Satorras, Alessandro Vespignani

The Internet, as well as many other networks, has a very complex connectivity recently modeled by the class of scale-free networks. This feature, which appears to be very efficient for a communications network, favors at the same time the spreading of computer viruses. We analyze real data from computer virus infections and find the average lifetime and prev

Chr. Rickwardt, P. Nielaba, M. H. Müser, K. Binder

We investigate the thermal expansion of crystalline SiO$_2$ in the $β$-- cristobalite and the $β$-quartz structure with path integral Monte Carlo (PIMC) techniques. This simulation method allows to treat low-temperature quantum effects properly. At temperatures below the Debye temperature, thermal properties obtained with PIMC agree better with experimental

V. Zlatic, B. Horvatic, B. Dolicki, S. Grabowski

We develop an efficient method to calculate the third-order corrections to the self-energy of the hole-doped two-dimensional Hubbard model in space-time representation. Using the Dyson equation we evaluate the renormalized spectral function in various parts of the Brillouin zone and find significant modifications with respect to the second-order theory even

M. J. Calderon, L. Brey

We make a quantum description of the electron low temperature properties of double exchange materials. In these systems there is a strong coupling between the core spin and the carriers spin. This large coupling makes the low energy spin waves to be a combination of ion and electron density spin waves. We study the form and dispersion of these composite spin

Titusz Feher, Andras Janossy, Gabor Oszlanyi, Ferenc Simon

We have measured the spin susceptibility of the underdoped high temperature superconductor, YBa2Cu4O8 by Gd^{3+} electron spin resonance in single crystals and aligned powders at several magnetic fields between 3 and 15.4 T. At low temperatures and high fields, the spin susceptibility of the CuO2 planes is enhanced slightly in the $B\parallel c$ orientation

S. A. Levetas, M. J. Godfrey, P. Dawson

Analysis of an exactly soluble model of phonons coupled to a carrier in a quantum dot provides a clear illustration of a phonon bottleneck to relaxation. The introduction of three-phonon interactions leads to a broad window for relaxation by the processes of LO phonon scattering and decay.

Ilaria Meccoli, Massimo Capone

We study the small-polaron problem of a single electron interacting with the lattice for the Holstein model in the adiabatic limit on a comb lattice, when the electron-phonon interaction acts only on the base sites. The ground state properties can be easily deduced from the ones of a linear chain with an appropriate rescaling of the coupling constant. On the

Tai-Kai Ng, Wai-Tak Leung

Using a Ginsburg-Landau free energy functional, we study the $H-T$ phase diagram of a weak magnetic superconductor, where the magnetization from the magnetic component is marginal in supporting a spontaneous vortex phase in absence of external magnetic field. In particular, the competition between the spiral state and spontaneous vortex phase is analysed. Ou

Tai-Kai Ng

We study in this paper the properties of a gas of fermions coupling to a U(1) gauge field at wavevectors $q<Λ<<k_F$ at dimensions larger than one, where $Λ<<k_F$ is a high momentum cutoff and $k_F$ is the fermi wave vector. In particular, we shall consider the $e^2\to\infty$ limit where charge and current fluctuations at wave vectors $q<Λ$ are forbidden. Wit

S. Sugai, N. Hayamizu

The dynamical stripe structure relating to the &#34;1/8 problem&#34; was investigated in La$_{2-x}$Sr$_x$CuO$_4$ utilizing the high frequency response of Raman scattering. The split of the two-magnon peak due to the formation of the stripe structure was observed at whole Sr concentration region from $x=0.035$ to 0.25 at low temperatures. Especially clear spl

C. U. Jung, J. Y. Kim, Mun-Seog Kim, S. Y. Lee

We report the high-pressure synthesis of the electron-doped infinite-layer superconductor Sr_{0.9}La_{0.1}CuO_{2}. A Rietveld analysis using X-ray powder diffraction data showed that, within the resolution of the measurement, the sample was purely an infinite-layer structure without any discernible impurities. The superconducting volume fraction and the tran

Matthew Enjalran, Richard T. Scalettar, Susan M. Kauzlarich

We present results from a Monte Carlo investigation of a simple bilayer model with geometrically frustrated interactions similar to those found in the mixed layer pnictide oxides $(Sr_{2}Mn_{3}Pn_{2}O_{2}, Pn=As,Sb).$ Our model is composed of two inequivalent square lattices with nearest neighbor intra- and interlayer interactions. We find a ground state com

Lloyd N. Trefethen, Marco Contedini, Mark Embree

There has been much recent interest, initiated by work of the physicists Hatano and Nelson, in the eigenvalues of certain random non-Hermitian periodic tridiagonal matrices and their bidiagonal limits. These eigenvalues cluster along a &#34;bubble with wings&#34; in the complex plane, and the corresponding eigenvectors are localized in the wings, delocalized

A. Osterloh, L. Amico, U. Eckern

A class of integrable one-dimensional models presented by Shastry and Schulz is consequently extended to the whole class of one-dimensional Hubbard- or XXZ-type models with correlated gauge-like hopping. A complete characterization concerning solvability by coordinate Bethe ansatz of this class of models is found.

Trevor C. Weekes

The status of VHE Astronomy is reviewed

Sabatino Sofia, Linghuai H. Li

Whereas a variation of the solar luminosity, L, will inevitably cause a similar change of the total solar irradiance, S, the opposite is not true. In fact, the bulk of the days to months variations of S can be explained entirely in terms of the passage of active regions across the solar disk. In this case, L remains essentially unchanged. For the total irrad

Sara L. Ellison, Max Pettini, Charles C. Steidel, Alice E. Shapley

We present the results of a series of imaging and spectroscopic observations aimed at identifying and studying the galaxy responsible for the z = 3.38639 damped lya system in the z = 3.61 QSO Q0201+1120. We find that the DLA is part of a concentration of matter which includes at least four galaxies (probably many more) over linear comoving dimensions, greate

Nir J. Shaviv

We present a model for the steady state winds of super-Eddington systems. These radiatively driven winds are expected to be optically thick and clumpy as they arise from a porous atmosphere. The model is then used to derive the mass loss of bright classical novae. The long duration super-Eddington outflows that are clearly observed in at least two cases (Nov

Nir J. Shaviv

Atmospheres having a significant radiative support are shown to be intrinsically unstable at luminosities above a critical fraction Gamma_crit ~ 0.5-0.85 of the Eddington limit, with the exact value depending on the boundary conditions. Two different types of absolute radiation-hydrodynamic instabilities of acoustic waves are found to take place even in the

K. K. Dyer, S. P. Reynolds, K. J. Borkowski, G. E. Allen

The remnant of SN 1006 has an X-ray spectrum dominated by nonthermal emission, and pre-ASCA observations were well described by a synchrotron calculation with electron energies limited by escape. We describe the results of a much more stringent test: fitting spatially integrated ASCA GIS (0.6-8 keV) and RXTE PCA (3-10 keV) data with a combination of the sync

G. A. Tammann, A. Sandage, A. Saha

The Hubble diagrams in B, V, and I of a complete sample of 35 SNeIa with (B-V) < 0.06 and 1200 < v < 30000 kms^{-1} have a scatter of only 0.1 mag, after small corrections are applied for differences in decline rate Delta m_{15} and color (B-V). The tightness of the Hubble diagrams proves blue SNeIa to be the best ``standard candles&#39;&#39; known. Their ab

S. F. Sanchez, C. R. Benn

Spanish astronomy has grown rapidly during the 1990s. The number of papers published per year has doubled, to about 4% of the world total. The number of high-impact papers, however, remains constant at about 1% of the world total. Papers from France, Germany and Italy also have lower impact than their numbers suggest, while for the US, UK, Japan, Netherlands

Chris J. Willott, Steve Rawlings, Katherine M. Blundell, Mark Lacy

We measure the radio luminosity function (RLF) of steep-spectrum radio sources using three redshift surveys of flux-limited samples selected at low (151 & 178 MHz) radio frequency, low-frequency source counts and the local RLF. The redshift surveys used are the new 7C Redshift Survey (7CRS) and the brighter 3CRR and 6CE surveys totalling 356 sources with vir

Nicholas Cross, Simon Driver, David Lemon

We discuss the quantification of the local galaxy population and the impact of the ``New Era of Wide-Field Astronomy&#39;&#39; on this field, and, in particular, systematic errors in the measurement of the Luminosity Function. New results from the 2dFGRS are shown in which some of these selection effects have been removed. We introduce an INT-WFS project whi

Gavin Ramsay, France Cordova, Jean Cottam, Keith Mason

We present XMM-Newton X-ray spectra of the disc accreting cataclysmic variable OY Car, which were obtained during the performance verification phase of the mission. These data were taken 4 days after a short outburst. In the EPIC spectra we find strong iron Kalpha emission with weaker iron Kbeta emission together with silicon and sulphur lines. The spectra a

Andrzej M. Soltan, Michael J. Freyberg

The first positive detection of the X-ray background fluctuations at small angular scales is reported. ROSAT PSPC archive pointed observations are used to measure fluctuations at scales of 0.03 - 0.4 deg. The pointings have been selected from an area free from galactic contamination. At separations below 0.1 deg clusters of galaxies become a substantial sour

Sean G. Ryan, Timothy C. Beers, Toshitaka Kajino, Katarina Rosolankova

We present data for four ultra-Li-deficient, warm, halo stars. The Li deficiency of two of these is a new discovery. Three of the four stars have effective temperatures Teff ~ 6300 K, in contrast to previously known Li-deficient halo stars which spanned the temperature range of the Spite Plateau. In this paper we propose that these, and previously known ultr

Sean G. Ryan, Toshitaka Kajino, Timothy C. Beers, Takeru Ken Suzuki

We have measured the Li abundance of 18 stars with -2 <~ [Fe/H] ~< -1 and 6000 K <~ Teff <~ 6400 K, a parameter range that was poorly represented in previous studies. We examine the Galactic chemical evolution (GCE) of this element, combining these data with previous samples of turnoff stars over the full range of halo metallicities. We find that A(Li) incre

P. W. Lucas, Katherine M. Blundell, P. F. Roche

We report the results of a survey of low mass Class I protostars in the cm continuum. In the initial survey, seven sources in the Taurus star formation were observed with the VLA at 0``.25 resolution. All seven sources drive CO outflows and display Herbig-Haro flows in the optical or near infrared wavebands. 4/7 sources were detected, two of which are new di

Andrea Biviano

I review the history of scientific research on galaxy clusters, from 1784, the year of publication of Messier&#39;s catalogue, to 1983, the year of George O. Abell&#39;s premature death. My review covers four main topics: 1) the distribution of clusters, 2) the cluster components, 3) the cluster structure, 4) the evolution of clusters. I consider both theore

Renzo Sancisi, Filippo Fraternali, Tom Oosterloo, Gustaaf van Moorsel

We discuss the distribution and kinematics of neutral hydrogen in the halos of spiral galaxies. We focus in particular on new results obtained for the nearby Sc galaxy NGC 2403 which have revealed the presence of extended HI emission (here referred to as the `beard&#39;) at anomalous velocities with respect to the `cold&#39; HI disk. Modeling shows that this

J. J. Salzer, C. Gronwall, V. A. Lipovetsky, A. Kniazev

The KPNO International Spectroscopic Survey (KISS) is a new objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors, and is the first purely digital objective-prism survey for emission-line galaxies. Here we present the first list o

Pavel Kroupa

A dense-enough gas-accumulation evolves, over a few Myr of intensifying star formation, to an embedded cluster. If it contains a sufficient amount of mass, O stars form and explosively expel the remaining gas, whereas poorer clusters reduce their embryonic gas content more gradually. The sudden expulsion of gas unbinds most of a rich cluster, but a significa

Pavel Kroupa

The preponderance of binary systems in all known stellar populations makes them exciting dynamical agents for research on topics as varied as star formation, star-cluster dynamics and the interiors of young and old stars. Today we know that the Galactic-field binary population is probably a dynamically evolved version of the Taurus-Auriga pre-main sequence p

Alexander Friedland

We reexamine the conventional physical description of the neutrino evolution inside the Sun. We point out that the traditional resonance condition has physical meaning only in the limit of small values of the neutrino mixing angle, theta<<1. For large values of theta, the resonance condition specifies neither the point of the maximal violation of adiabaticit

S. R. Beane, P. F. Bedaque, L. Childress, A. Kryjevski

We show that a central $1/r^n$ singular potential (with $n\geq 2$) is renormalized by a one-parameter square-well counterterm; low-energy observables are made independent of the square-well width by adjusting the square-well strength. We find a closed form expression for the renormalization-group evolution of the square-well counterterm.

J. Jalilian-Marian, K. Orginos, I. Sarcevic

We calculate the inclusive cross section for prompt photon production in heavy-ion collisions at RHIC energies ($\sqrt{s}=130$ GeV and $\sqrt{s}=200$ GeV) in the central rapidity region including next-to-leading order, $O(α_{em}α_s^2)$, radiative corrections, initial state nuclear shadowing and parton energy loss effects. We show that there is a significant

Takahiro Kubota, Jian-Ge Zhou

By exploiting the correspondence between the Cardy boundary state in SU(2) group manifold and the BPS D3-brane configuration in the full asymptotically flat geometry of NS5-branes, we show that the Hanany-Witten effect in 10D background is encoded in the Cardy boundary states. The two RR Page D0 charges of the $n$-th spherical D2-brane due to the contraction

Marcelo R. Ubriaco

We study the consequences of introducing quantum group invariance in the formalism of nonextensive quantum statistical mechanics. We find that the corresponding thermodynamical system is equivalent to a Bose-Einstein gas in the Boltzmann-Gibbs formalism with a higher critical temperature than the standard Bose-Einstein case.

Paul Bode, Jeremiah P. Ostriker, Neil Turok

Discrepancies have emerged between the predictions of standard cold dark matter (CDM) theory and observations of clustering on sub-galactic scales. Warm dark matter (WDM) is a simple modification of CDM in which the dark matter particles have initial velocities due either to their having decoupled as thermal relics, or having been formed via non-equilibrium

Alexander Yu. Vlasov

In this paper is shown an application of Clifford algebras to the construction of computationally universal sets of quantum gates for $n$-qubit systems. It is based on the well-known application of Lie algebras together with the especially simple commutation law for Clifford algebras, which states that all basic elements either commute or anticommute.

L. A. Ferreira, J. Sanchez-Guillen

We show that the Skyrme theory possesses a submodel with an infinite number of local conserved currents. The constraints leading to the submodel explore a decomposition of SU(2) with a complex field parametrizing the symmetric space SU(2)/U(1) and a real field in the direction of U(1). We demonstrate that the Skyrmions of topological charges $\pm 1$ belong t

Kasper Peeters, Pierre Vanhove, Anders Westerberg

Higher-derivative terms in the string and M-theory effective actions are strongly constrained by supersymmetry. Using a mixture of techniques, involving both string amplitude calculations and an analysis of supersymmetry requirements, we determine the supersymmetric completion of the R^4 action in eleven dimensions to second order in the fermions, in a form

J. F. Beacom, R. N. Boyd, A. Mezzacappa

Early black hole formation in core-collapse supernovae may be triggered by mass accretion or a change in the high-density equation of state. We consider the possibility that black hole formation happens when the flux of neutrinos is still measurably high. If this occurs, then the neutrino signal from the supernova will be terminated abruptly (the transition

Jose M. M. Senovilla, Raul Vera

We present an explicit three-parameter class of $p=γ\varrho$, ($-1/3\leqγ<1$), cosmological models admitting a two-dimensional group $G_{2}$ of isometries acting on spacelike surfaces. The family is self-similar in the sense that it has a further homothetic vector field and it contains subfamilies of both (previously unknown) tilted and non-tilted Bianchi mo

S. Pepin, A. Schaefer

A high density diquark phase seems to be a generic feature of QCD. If so it should also be reproduced by random matrix models. We discuss a specific one in which the random matrix elements of the Dirac operator are supplemented by a finite chemical potential and by non-random elements which model the formation of instanton-anti-instanton molecules. Comparing

Michele Cini, Enrico Perfetto, Gianluca Stefanucci

We introduce a {\em local} formalism, in terms of eigenstates of number operators, having well defined point symmetry, to solve the Hubbard model at weak coupling on a $N\times N$ square lattice (for even $N$). The key concept is that of W=0 states, that are the many-body eigenstates of the kinetic energy with vanishing Hubbard repulsion. At half filling, th

Peter Huebner

We use the conformal approach to numerical relativity to evolve hyperboloidal gravitational wave data without any symmetry assumptions. Although our grid is finite in space and time, we cover the whole future of the initial data in our calculation, including future null and future timelike infinity.

Pei-Ming Ho

Using a D0-brane as a probe, we study the spacetime geometry in the neighborhood of N D-branes in matrix theory. We find that due to fermionic zero modes, the coordinates of the probe in the transverse directions are noncommutative, and the angular part is a fuzzy sphere.

Michael Frank, David R. Larson

We present a general approach to a modular frame theory in C*-algebras and Hilbert C*-modules. The investigations rely on the idea of geometric dilation to standard Hilbert C*-modules over unital C*-algebras that possess orthonormal Hilbert bases, and of reconstruction of the frames by projections and by other bounded modular operators with suitable ranges.

M. Abel, A. Celani, D. Vergni, A. Vulpiani

The problem of front propagation in flowing media is addressed for laminar velocity fields in two dimensions. Three representative cases are discussed: stationary cellular flow, stationary shear flow, and percolating flow. Production terms of Fisher-Kolmogorov-Petrovskii-Piskunov type and of Arrhenius type are considered under the assumption of no feedback o

M. N. Kiselev, H. Feldmann, R. Oppermann

We represent the generators of the SU(N) algebra as bilinear combinations of Fermi operators with imaginary chemical potential. The distribution function, consisting of a minimal set of discrete imaginary chemical potentials, is found for arbitrary N. This representation leads to the conventional temperature diagram technique with standard Feynman codex, exc

D. Taras-Semchuk, K. B. Efetov

We consider a two-dimensional electron gas with long range disorder. Assuming that time reversal symmetry is broken either by an external magnetic field or, as in the case of a delta-correlated random magnetic field, by the disorder itself, we derive a supermatrix $σ$-model. As an intermediate step, we provide a microscopic derivation of the ballistic $σ$-mo

H. Ochiai, K. Sato

We investigate the dynamics of vacuum brane and the bulk in dilatonic brane world. We present exact dynamical solutions which describe the vacuum dilatonic brane world. We find that the solution has initial singularity and singularity at spatial infinity.

Yongseok Oh, Taesoo Song, Su Houng Lee

We reanalyze the dissociation process of the $J/ψ$ by $π$ and $ρ$ mesons into $D + \bar{D}$, $D^* + \bar{D}$, $D + \bar{D}^*$, and $D^* + \bar{D}^*$ within a meson exchange model. In addition to the dissociation mechanisms considered in the literature, we consider anomalous parity interactions, whose couplings are constrained by heavy quark spin symmetry and

D. Serban

We study the vortex solutions in a multicomponent Zhang-Hansson-Kivelson model for the fractional quantum Hall effect, at the self-dual point. Vortices with minimal free energy represent Laughlin quasiholes. We find at least two classes of solutions, distinguished by their global invariance, or by the number of conserved charges.

Wung-Hong Huang

We evaluate the one-loop correction to the spectrum of Kaluza-Klein system for the $ϕ^3$ model on $R^{1,d}\times (T_θ^2)^L$, where $1+d$ dimensions are the ordinary flat Minkowski spacetimes and the extra dimensions are the L two-dimensional noncommutative tori with noncommutativity $θ$. The correction to the Kaluza-Klein mass spectrum is then used to comput

F. Thiele, Ch. Fuchs, R. v. Baltz

The optical absorption of a single spherical semiconductor quantum dot in an electrical field is studied taking into account the nonlocal coupling between the field of the light and the polarizability of the semiconductor. These nonlocal effects lead to a small size anf field dependent shift and broadening of the excitonic resonance which may be of interest

Alexander I. Nesterov, L. V. Sabinin

In the framework of nonassociative geometry (hep-th/0003238) a unified description of continuum and discrete spacetime is proposed. In our approach at the Planck scales the spacetime is described as a so-called &#34;diodular discrete structure&#34; which at large spacetime scales `looks like&#39; a differentiable manifold. After a brief review of foundations

D. Bruss, G. M. D&#39;Ariano, C. Macchiavello, M. F. Sacchi

We show that nonlocality of quantum mechanics cannot lead to superluminal transmission of information, even if most general local operations are allowed, as long as they are linear and trace preserving. In particular, any quantum mechanical approximate cloning transformation does not allow signalling. On the other hand, the no-signalling constraint on its ow

D. A. Slavnov

Within the framework of the algebraic approach the problem of hidden parameters in quantum mechanics is surveyed. It is shown that the algebraic formulation of quantum mechanics permits introduction of a specific hidden parameter, which has the form of nonlinear functional on the algebra of observables. It is found out that the reasoning of von Neumann and o

Paolo Ghigna, Melissa di Muri, Giorgio Spinolo

The frequency distribution of different parameters of an EXAFS spectrum can be directly sampled by analysing a population of simulated spectra produced by adding computer-generated noise to a reference pattern. The procedure gives statistical estimators of the parameter obtained with different data processing strategies to test the performance of a strategy,

Agris Gailitis, Olgerts Lielausis, Ernests Platacis, Sergej Dement&#39;ev

After the dynamo experiment in November 1999 had shown magnetic field self-excitation in a spiraling liquid metal flow, in a second series of experiments emphasis was placed on the magnetic field saturation regime as the next principal step in the dynamo process. The dependence of the strength of the magnetic field on the rotation rate is studied. Various fe

A. Mary Selvam

The complex spaciotemporal patterns of atmospheric flows that result from the cooperative existence of fluctuations ranging in size from millimetres to thousands of kilometres are found to exhibit long-range spacial and temporal correlations. These correlations are manifested as the self-similar fractal geometry of the global cloud cover pattern and the inve

Hartmuth Arenhövel

The development of theoretical photonuclear physics over the last 40 years is illustrated by a few selected examples highlighting a number of important issues like collective motion in nuclei, the role of subnuclear degrees of freedom, relativity and meson production.

V. K. Magas, L. P. Csernai, D. Strottman

A model for energy, pressure and flow velocity distributions at the beginning of relativistic heavy ion collisions is presented, which can be used as initial condition for hydrodynamical calculations. The results show that QGP forms a tilted disk, such that the direction of the largest pressure gradient stays in the reaction plane, but deviates from both the

G. G. Petratos, I. R. Afnan, F. Bissey, J. Gomez

We discuss a possible measurement of the ratio of the nucleon structure functions, F2n/F2p, and the ratio of the up to down quark distributions, u/d, at large x, by performing deep inelastic electron scattering from the 3H and 3He mirror nuclei with the 11 GeV upgraded beam of Jefferson Lab. The measurement is expected to be almost free of nuclear effects, w

Maciej Blaszak

In the paper, developing the idea of V. Sokolov et all. (J.Math.Phys. 40 (1999)6473 we construct recursion operators and hereditary algebra of symmetries for many field and lattice systems.

J. A. M. Vermaseren

Version 3 of FORM is introduced. It contains many new features that are inspired by current developments in the methodology of computations in quantum field theory. A number of these features is discussed in combination with examples. In addition the distribution contains a number of general purpose packages. These are described shortly.

Vinay Deolalikar

Certain towers of function fields with complete splitting of rational places at each stage are constructed. Also, families oof towers with positive N/g ratios are described.

Vinay Deolalikar

We introduce the notion of &#34;quasi-symmetric&#34; polynomials, which is a generalization of the notion of symmetry, and is particularly suited to the setting of polynomial rings over finite fields. The properties of this new class of functions are studied. It is then shown that quasi-symmetric polynomials are very useful in splitting rational places in ex

Vinay Deolalikar

The notion of symmetry in polynomial rings with several indeterminates is generalized to polynomial rings over finite fields. Families of extensions of the projective line over a finite field of constants possessing this property are explicitly constructed. These extensions exhibit complete splitting of all finite rational places. Subcovers of these extensio

Maks A. Akivis, Vladislav V. Goldberg

The authors study smooth lines on projective planes over the algebra C of complex numbers, the algebra C^1 of double numbers, and the algebra C^0 of dual numbers. In the space RP^5, to these smooth lines there correspond families of straight lines describing point three-dimensional tangentially degenerate submanifolds X^3 of rank 2. The authors study focal p