December 2000 arXiv papers — page 2

Theo de Jong

Let $C$ be an isolated plane curve singularity, and $(C,l)$ be a decorated curve. In this article we compare the equisingular deformations of $C$ and the sandwiched singularity $X(C,l)$. We will prove that for $l \gg 0$ the functor of equisingular deformations of $C$ and $(C,l)$ are equivalent. From this we deduce a proof of a formula for the dimension of th

Daniel Lenz

Paper withdrawn; will be replaced by revised version containing application to lattice models as well. We study hierarchical properties of Sturmian words. These properties are similar to those of substitution dynamical systems. This approach allows one to carry over to Sturmian dynamical systems methods developed in the context of substitutions. For example,

Aníbal Iucci, Kang Li, Carlos M. Naón

We extend a non local and non covariant version of the Thirring model in order to describe a many-body system with spin-flipping interactions By introducing a model with two fermion species we are able to avoid the use of non abelian bosonization which is needed in a previous approach. We obtain a bosonized expression for the partition function, describing t

Adrián R. Lugo

We develop a systematic perturbative expansion and compute the one-loop two-points, three-points and four-points correlation functions in a non-commutative version of the U(N) Wess-Zumino-Witten model in different regimes of the $θ$-parameter showing in the first case a kind of phase transition around the value $θ_c = \frac{\sqrt{p^2 + 4 m^2}}{Λ^2 p}$, where

Guillermo A. Silva

In the thesis we analize different problems related to the supersymmetric extension of the Dirac-Born-Infeld action. In chapter 2 we introduce the DBI action and show how it appears in string theory, we discuss also it's connection with Dp-branes. Chapter 3 is a self contained introduction to supersymmetry, with emphasis on BPS states. In chapter 4 we co

G. S. Lozano, E. F. Moreno, F. A. Schaposnik

We construct exact soliton solutions to the Chern-Simons-Higgs system in noncommutative space, for non-relativistic and relativistic models. In both cases we find regular vortex-like solutions to the BPS equations which approach the ordinary selfdual non-topological and topological solitons when the noncommutative parameter $\theta$ goes to zero.

Hans Peter Nilles

The smallness of the cosmological constant is one of the basic problems in particle physics and cosmology. Various attempts have been made to explain this mystery, but no satisfactory solution has been found yet. The appearance of extra dimensions in the framework of brane world systems seems to provide some new ideas to address this problem from a different

E. R. Bezerra de Mello, V. B. Bezerra, N. R. Khusnutdinov

Using the zeta function regularization method we calculate the ground state energy of scalar massive field inside a spherical region in the space-time of a point-like global monopole. Two cases are investigated: (i) We calculate the Casimir energy inside a sphere of radius $R$ and make an analytical analysis about it. We observe that this energy may be posit

V. D. Ivashchuk

An introduction to supersymmetric (SUSY) solutions defined on the product of Ricci-flat spaces in D= 11 supergravity is presented. The paper contains some background information: (i) decomposition relations for SUSY equations and (ii) 2^{-k}-splitting theorem that explains the appearance of N = 2^{-k} fractional supersymmetries. Examples of M2 and M5 branes

Corneliu Sochichiu

We show that the p-dimensional noncommutative Yang--Mills model corresponding to a (p-1)-brane allows solutions which correspond to lower branes. This may be interpreted as the Morita equivalence of noncommutative planes of various dimensions.

Heui-Seol Roh

This study proposes that the longstanding problems of quantum chromodynamics (QCD) as an SU(3)_C gauge theory, the confinement mechanism and Θvacuum, can be resolved by dynamical spontaneous symmetry breaking (DSSB) through the condensation of singlet gluons and quantum nucleardynamics (QND) as an SU(2)_N x U(1)_Z gauge theory is produced. The confinement me

Alan Kostelecky, Agnes Roberts

Analogue models for CP violation in neutral-meson systems are studied in a general framework. No-go results are obtained for models in classical mechanics that are nondissipative or that involve one-dimensional oscillators. A complete emulation is shown to be possible for a two-dimensional oscillator with rheonomic constraints, and an explicit example with s

Philip G. Ratcliffe

A matrix-based approach to numerical integration of the DGLAP evolution equations is presented. The method arises naturally on discretisation of the Bjorken x variable, a necessary procedure for numerical integration. Owing to peculiar properties of the matrices involved, the resulting equations take on a particularly simple form and may be solved in closed

Stuart Raby

In this talk I discuss the qualitative features of an SO(10) SUSY GUT with an SU(2)x U(1)$^n$ family symmetry. I then describe the global fit of this theory to precision electroweak data [including charged fermion masses and mixing angles]. Finally, the predictions of the model for neutrino masses and mixing are discussed. The most predictive version of the

Michael I. Eides, Howard Grotch, Valery A. Shelyuto

The results and main steps of an analytic calculation of radiative-recoil corrections of order $α(Zα)^5(m/M)m$ to the Lamb shift in hydrogen are presented. The calculations are performed in the infrared safe Yennie gauge. The discrepancy between two previous numerical calculations of these corrections existing in the literature is resolved. Our new result el

S. Y. Choi, Seong Chan Park, J. H. Jang, H. S. Song

We study the elastic scattering of the lightest neutralino with a nucleus in the framework of the minimal supersymmetric standard model (MSSM) with explicit flavor preserving CP violation, including the one-loop CP-violating neutral Higgs-boson mixing effects induced dominantly by the CP phases in the top and bottom (s)quark sectors. We construct the most ge

Taro Nagao, Shinsuke M. Nishigaki

We derive nonlinear sigma models (chiral Lagrangians) over symmetric spaces U(n), U(2n)/Sp(2n), and U(2n)/O(2n) from U(N), O(N), and Sp(2N) lattice gauge theories coupled to n flavors of staggered fermions, in the large-N and g^2 N limit. To this end, we employ Zirnbauer's color-flavor transformation. We prove the spatial homogeneity of the vacuum config

F. -P. Schilling

A new H1 measurement of diffractive dijet and 3-jet production cross sections in diffractive deep inelastic scattering events of the type ep->eXY is presented. The data constrain well the diffractive gluon distribution. At low x-pom, a calculation based on perturbative QCD is in a reasonable agreement with the data.

Danilo Behnke, David Blaschke, Victor Pervushin, Denis Proskurin

We define the cosmological parameters $H_{c,0}$, $Ω_{m,c}$ and $Ω_{Λ, c}$ within the Conformal Cosmology as obtained by the homogeneous approximation to the conformal-invariant generalization of Einstein's General Relativity theory. We present the definitions of the age of the universe and of the luminosity distance in the context of this approach. A pos

Sascha Husa, Manuela Campanelli, Roberto Gomez, Jeffrey Winicour

We present a characteristic algorithm for computing the perturbations of a Schwarzschild spacetime by means of solving the Teukolsky equations. Our methods and results are expected to have direct bearing on the study of binary black holes presently underway using a fully {\em nonlinear} characteristic code \cite{Gomez98a}.

Vladimir V. Kassandrov, Joseph A. Rizcallah

The earlier proposed conditions of (bi)quaternionic differentiability are nonlinear, give rize to the 2-spinor and the self-dual gauge structures and may be considered as the it generating system of equations (GSE) with respect to the source-free Maxwell, Yang-Mills and eikonal equations. We present the general solution of the GSE in terms of twistor variabl

Pia Astone, Kazimierz M. Borkowski, Piotr Jaranowski, Andrzej Królak

We develop a set of data analysis tools for a realistic all-sky search for continuous gravitational-wave signals. The methods that we present apply to data from both the resonant bar detectors that are currently in operation and the laser interferometric detectors that are in the final stages of construction and commissioning. We show that with our technique

J. E. Hirsch

The theory of hole superconductivity proposes that the fundamental asymmetry between electrons and holes in solids is responsible for superconductivity. Here we point out a remarkable consequence of this theory: a tendency for negative charge to be expelled from the bulk of the superconductor towards the surface. Experimentally observable consequences of thi

Ting Lei, Raymond J. Hawkins

We compare observed corporate cumulative default probabilities to those calculated using a stochastic model based on an extension of the work of Black and Cox and find that corporations default as if via diffusive dynamics. The model, based on a contingent-claims analysis of corporate capital structure, is easily calibrated with readily available historical

K. Doerr, K. -H. Mueller, T. Walter, M. Sahana

We report on the non-linear in-plane electrical transport in coherently grown [La0.7Sr0.3MnO3/SrTiO3] multilayers with ultrathin (< 3 nm) single layers. Current-induced switching of the conductance, with low conductance at larger currents, is demonstrated. The conductance switching is modified under a magnetic field, resulting in an extremely large magnetore

A. V. Boris, P. Mandal, C. Bernhard, N. N. Kovaleva

Critical behavior of the infrared reflectivity of RuSr_2GdCu_2O_8 ceramics is observed near the superconducting T_{SC} = 45 K and magnetic T_M = 133 K transition temperatures. The optical conductivity reveals the typical features of the c-axis optical conductivity of strongly underdoped multilayer superconducting cuprates. The transformation of the Cu-O bend

L. Roters, S. Lubeck, K. D. Usadel

We analyze numerically a moving interface in the random-field Ising model which is driven by a magnetic field. Without thermal fluctuations the system displays a depinning phase transition, i.e., the interface is pinned below a certain critical value of the driving field. For finite temperatures the interface moves even for driving fields below the critical

Eduard Vives, Antoni Planes

The behaviour of the Random Anisotropy Ising model at T=0 under local relaxation dynamics is studied. The model includes a dominant ferromagnetic interaction and assumes an infinite anisotropy at each site along local anisotropy axes which are randomly aligned. Two different random distributions of anisotropy axes have been studied. Both are characterized by

E. V. Ivashkevich, A. M. Povolotsky, V. B. Priezzhev

Using the Bethe ansatz we obtain the exact solution for the one-dimensional asymmetric avalanche process. We evaluate the velocity of dispersive flow as a function of driving force and the density of particles. The obtained solution shows a dynamical transition from intermittent to continuous flow.

A. Bakai, A. Ciach, A. Chalyi, R. Folk

The paper contains materials of the discussion concerning phase transitions and critical phenomena which took place during the Workshop on modern problems of soft matter theory (Aug. 27 -- Aug. 31, 2000, Lviv, Ukraine).

O. Narikiyo

I point out that a magnetotransport theory on the basis of the fluctuation exchange (FLEX) approximation, which is proposed in order to explain anomalous transport properties in the normal state of high-$T_{\rm c}$ cuprate superconductors, is not compatible with the Fermi liquid theory and that the anomaly obtained there ascribes to the inconsistency of the

A. I. Akhiezer, A. A. Isayev, S. V. Peletminsky, A. A. Yatsenko

Superfluid-to-superfluid phase transitions in a Fermi-liquid leading to the emergence of two-gap superfluid states have been studied. There are considered the systems of fermions of one and two (nuclear matter) sorts. The self-consistent equations describing new two-gap superfluid states have been obtained. These equations differ essentially from the equatio

W. Kluzniak

The basic observed properties of neutron stars are reviewed. I suggest that neutron stars in low-mass X-ray binaries are the best of all known sites for testing strong-field effects of general relativity.

P. Amsterdamski, T. Bulik, D. Gondek-Rosinska, W. Kluzniak

We show that in the limit of low masses (M<0.1M solar), the orbital and rotational frequencies in exact relativistic numerical models of rotating, axially symmetric, quark stars coincide with those for Maclaurin spheroids. In particular, when the eccentricity of the spheroid exceeds a critical value (e>0.83458318), circular orbits in the equatorial plane are

Bradley C. Whitmore

The ability of HST to resolve objects ten times smaller than possible from the ground has rejuvenated the study of young star clusters. A recurrent morphological theme found in nearby resolved sytems is the observation of young (typically 1 - 10 Myr), massive (10**3 - 10**4 M_sun), compact (rho ~ 10**5 M_sun/pc**3) clusters which have evacuated the gas and d

L. G. Althaus, A. M. Serenelli, O. G. Benvenuto

We investigate the effects of element diffusion on the structure and evolution of low-mass helium white dwarfs (WD). Attention is focused on the occurrence of hydrogen shell flashes induced by diffusion processes during cooling phases. Initial models from 0.406 to 0.161 solar masses are constructed by applying mass loss rates at different stages of the RGB e

W. Kluzniak

After reviewing the general-relativistic ``gap&#39;&#39; model of accretion, I discuss its relation to the high frequency quasi-periodic oscillations observed in low-mass X-ray binaries. The ``300&#39;&#39; Hz frequency seen in some X-ray bursts may be a relativistic signature of keplerian rotation of the neutron star.

D. Gondek-Rosinska, P. Haensel, J. L. Zdunik

We find constraints on minimum and maximum mass of ordinary neutron stars imposed by their early evolution (protoneutron star stage). We calculate models of protoneutron stars using a realistic standard equation of state of hot, dense matter valid for both supranuclear and subnuclear densities. Results for different values of the nuclear incompressibility ar

Guillermo Torres

Eclipses in the 14.4-day period double-lined binary SS Lac were observed photographically and visually early in the 20th century, but stopped some 50 or 60 years ago. This has been explained by the presence of a distant third star in the system, which has now been detected spectroscopically with a period of 679 days. The plane of the orbit of the binary is c

D. Gondek, P. Haensel, J. L. Zdunik

Constraints on minimum and maximum mass of ordinary neutron stars are imposed by the consideration of their early evolution (protoneutron star stage). Calculations are performed for a realistic standard model of hot, dense matter (Lattimer & Swesty 1991) valid for both supranuclear and subnuclear densities. Various assumptions concerning protoneutron star in

D. Gondek-Rosinska, T. Bulik, w. Kluzniak, J. L. Zdunik

It has been suggested that observations of quasi periodic oscillations (QPOs) in the X-ray fluxes from low mass X-ray binaries can be used to constrain the mass of the compact object and the equation of state of its matter. A specific suggestion that the kHz QPO frequency saturates at the maximum orbital frequency has been widely considered. We examine rotat

M. Einasto, J. Einasto, E. Tago, H. Andernach

We present a comparison of Abell and APM clusters of galaxies as tracers of the large scale structure of the Universe. We investigate selection functions of both cluster catalogs. We show that the supercluster-void network can be traced with both cluster samples; the network has a well-defined period of ~120 h^{-1} Mpc. We calculate the correlation function

E. Tago, J. Einasto, M. Einasto, V. M&#34;uller

We study the space distribution of Abell and X-ray selected clusters of galaxies from the ROSAT Bright Source Catalog, and determine correlation functions for both cluster samples. On small scales the correlation functions depend on the cluster environment: clusters in rich superclusters have a larger correlation length and amplitude than all clusters. On la

M. Einasto, J. Einasto, E. Tago, V. M&#34;uller

We study the distribution of X-ray selected clusters of galaxies with respect to superclusters determined by Abell clusters of galaxies and show that the distribution of X-ray clusters follows the supercluster-void network determined by Abell clusters. We find that in this network X-ray clusters are more strongly clustered than other clusters. Poor, non-Abel

A. S. Trushkina, A. G. Gubanov

New services for Clusters of Galaxies Database created in the Astronomical Institute of SPbU have been constructed. The detailed description of database and its content is available at http://www.astro.spbu.ru/CLUSTERS/. The information contained in the database can be used for solution of the specific astronomical problems. One of these problems is the rese

Indranil Chattopadhyay, Sandip K. Chakrabarti

Jets and outflows are known to form out of advective accretion flows around black holes. Hard photons from the centrifugal barrier directly hit the electrons and deposit momentum on them. For optically thick flows such deposition is not efficient, but for optically thin flows matter could be accelerated to relativistic speed. In fact, even bound matter could

Indranil Chattopadhyay, Sandip K. Chakrabarti

We propose the processes of generation and radiative acceleration of jets from the centrifugal pressure dominated boundary layer around a black hole.

C. Spiering

This talk summarizes the main physics goals and basic methods of telescopes for high energy neutrinos. It reviews the present status of deep underwater telescopes and sketches the ICECUBE project as an example for a cube kilometer detector. It is suggested to develop techniques for radio and acoustic detection hand in hand with big optical arrays. These larg

Sandip K. Chakrabarti, Indranil Chattopadhyay

Bulk motion Comptonization utilizes properties of both matter and radiation close to the horizon of a black hole. Computation with these considerations produce hard tails of energy spectral slope $\sim 1.5-1.7$. These are the most direct evidence of the horizon of a black hole. We argue that even in presence of winds and outflows this property is not likely

Sandip K. Chakrabarti

We report all possible basic solutions of an advective disk model and use them to explain major observations from black hole candidates.

Sandip K. Chakrabarti

Since black holes can only accrete sub-Keplerian matter, a companion black hole orbiting on a circular and instantaneously Keplerian orbit around a central, massive black hole in a galactic Centre will loss angular momentum and energy to the accreting matter. This loss could be a significant fraction of the loss due to gravitational wave (GW) emission. The c

Sandip K. Chakrabarti, A. Nandi, S. G. Manickam

We report some properties of the light curves of GRS 1915+105 and present their interpretation using the variation of net accretion rate.

Anuj Nandi, Sivakumar G. Manickam, A. R. Rao, Sandip K. Chakrabarti

A few classes of the light curve of the black hole candidate GRS 1915+105 have been analyzed in detail. We discover that unlike the previous findings, QPOs occasionally occur even in the so-called `On&#39; or softer states. Such findings may require a revision of the accretion/wind scenario of the black hole candidates. We conjecture that considerable winds

Sandip K. Chakrabarti, Anuj Nandi

Advective disk paradigm of black hole accretion includes self-consistent formation of shocks and outflows from post-shock region. We apply this paradigm to understand rich variation of the light curve of the black hole candidate GRS1915+105. We propose that out of five possible {\it fundamental states} the black hole candidate GRS1915+105 moves around among

Sandip K. Chakrabarti, S. G. Manickam, A. Nandi, A. R. Rao

We interpret observed features of the black hole candidate GRS1915+105 in the light of the advective flow paradigm. The light curve of this black hole is seen to be of four classes, Soft, Hard, Semi-Soft and Intermediate. Each class can display more than one type of light curve making altogether twelve or more types of light curves. In each type, the mode of

Sandip K. Chakrabarti

Advective accretion disks and winds are the most self-consistent solutions today. We describe this paradigm briefly and show how it attempts to explain some of the interesting observations of the galactic microquasar GRS1915+105.

Anuj Nandi, Sivakumar G. Manickam, Sandip K. Chakrabarti

The black hole candidate GRS 1915+105 exhibits a rich variety of variability. Assuming that the earlier paradigm of black hole accretion which includes a shock is applicable for this system as well, one can classify these variabilities into four classes. We present light curves of these classes and discuss the basis of our classification.

Sandip K. Chakrabarti

We show that outflow rates in jets directly depend on the spectral states of black holes. In particular, in soft states, when the Comptonized electrons are cold, outflow rate is close to zero. In hard states, outflow could be steady, but the rate may be very small -- only a few percent of the inflow. In the intermediate states, on the other hand, the outflow

Sandip K. Chakrabarti

Jets and outflows must be produced directly from accretion disks and inflows, especially when the central gravitating objects are compact, such as neutron stars and black holes, and themselves are {\it not} mass losing. Here, we review the formation of jets from advective inflows. We show that the centrifugal pressure supported boundary layer (CENBOL) of the

Y. -H. Chu

Supernovae descendent from massive stars explode in media that have been modified by their progenitors&#39; mass loss and UV radiation. The supernova ejecta will first interact with the circumstellar material shed by the progenitors at late evolutionary stages, and then interact with the interstellar material. Circumstellar nebulae in supernova remnants can

H. G. Dosch, O. Nachtmann, T. Paulus, S. Weinstock

We examine diffractive proton-proton scattering p p -> p X and photo- and electroproduction of ρ^0 mesons γ^(*) p -> ρ^0 X, where X denotes a proton or a final state, into which the proton can go by diffractive dissociation. Using a functional integral approach we derive the scattering amplitudes, which are governed by the expectation values of light-like We

Manuela Campanelli, Roberto Gomez, Sascha Husa, Jeffrey Winicour

We present a characteristic algorithm for computing the perturbation of a Schwarzschild spacetime by means of solving the Teukolsky equation. We implement the algorithm as a characteristic evolution code and apply it to compute the advanced solution to a black hole collision in the close approximation. The code successfully tracks the initial burst and quasi

Martin White, Lars Hernquist, Volker Springel

Recently there has been a lot of attention focussed on a virialized halo-based approach to understanding the properties of the matter and galaxy power spectrum. A key ingredient in this model is the number and distribution of galaxies within dark matter halos as a function of mass. This quantity has been predicted from semi-analytic modeling and from fits to

Celso de Camargo Barros Junior, Yogiro Hama

We study the low energy pion-hyperon interaction considering effective non-linear chiral invariant Lagrangians including pions, rho mesons, hyperons and corresponding resonances. Then we calculate the S- and P-wave phase-shifts, total cross sections, angular distributions and polarizations for the momentum in the center-of-mass frame up to k=400 MeV. With th

Tod E. Strohmayer

High amplitude, nearly coherent X-ray brightness oscillations during thermonuclear X-ray bursts were discovered with the Rossi X-ray Timing Explorer (RXTE) in early 1996. Spectral and timing evidence strongly supports the conclusion that these oscillations are caused by rotational modulation of the burst emission and that they reveal the spin frequency of ne

M. M. Block, A. B. Kaidalov

Using an eikonal analysis, we examine the validity of the factorization theorem for nucleon-nucleon, gamma p and gamma gamma collisions. As an example, using the additive quark model and meson vector dominance, we directly show that for all energies and values of the eikonal, that the factorization theorem sigma_{nn}/sigma_{gamma p} = sigma_{gamma p}/sigma_{

El Mostapha Sahraoui, El Hassan Saidi

We study solutions at the minima of scalar field potentials for Moyal spaces and torii in the large non-commutativity and interprete these solitons in terms of non-BPS D-branes of string theory. We derive a mass spectrum formula linking different D-branes together on quantum torii and suggest that it describes general systems of D-brane bound states extendin

D. Kutasov, D. A. Sahakyan

We study the high energy thermodynamics of Little String Theory, using its holographic description. This leads to the entropy-energy relation $S=\beta_H E+\alpha\log E+O(1/E)$. We compute $\alpha$ and show that it is negative; as a consequence, the high energy thermodynamics is unstable. We exhibit a mode localized near the horizon of the black brane, which

Anupam Mazumdar, Mohammad M. Sheikh-Jabbari

In this paper we show that noncommutativity in spatial coordinates can generate magnetic field in the early Universe on a horizon scale. The strength of such a magnetic field depends on the number density of massive charged particles present at a given moment. This allows us to trace back the temperature dependence of the noncommutativity scale from the boun

M. Salle, J. Smit, J. C. Vink

We study thermal behavior of a recently introduced Hartree ensemble approximation, which allows for non-perturbative inhomogeneous field configurations as well as for approximate thermalization, in the $ϕ^4$ model in 1+1 dimensions. Using ensembles with a free field thermal distribution as out-of-equilibrium initial conditions we determine thermalization tim

M. Itakura

With the help of the replica exchange Monte Carlo method and the improved Monte Carlo renormalization-group scheme, we investigate over a wide area in the phase diagram of the Gaussian random field Ising model on the simple cubic lattice. We found that the phase transition at a weak random field belongs to the same universality class as the zero-temperature

M. Fukushima, E. -M. Ilgenfritz, H. Toki

We consider full non-Abelian, Abelian and center projected lattice field configurations built up from random instanton gas configurations in the continuum. We study the instanton contribution to the $\bar{Q}Q$ force with respect to ({\it i}) instanton density dependence, ({\it ii}) Casimir scaling and ({\it iii}) whether various versions of Abelian dominance

A. V. Bratchikov

Using two WZNW theories for Lie algebras $g$ and $h, h\subset g,$ we construct the associative quotient algebra which includes a class of $g/h$ coset primary fields and currents.

K. Matsuda, N. Takeda, T. Fukuyama, H. Nishiura

We examine the constraints on the MNS lepton mixing matrix =66rom the present and future experimental data of the neutrino oscillation, tritium beta decay, and neutrinoless double beta decay for Majorana neutrinos. We show that the small mixing angle solutions for solar neutrino problem are disfavored for small averaged mass ($<m_ν>$) of neutrinoless double

V. Ch. Zhukovsky, K. G. Klimenko, V. V. Khudyakov, D. Ebert

In the framework of a (2+1)-dimensional P-even massive Gross-Neveu model, an external magnetic field is shown to induce a parity breaking first order phase transition. Possibility of applying the results obtained to description of magnetic phase transitions in high-temperature superconductors is discussed.

K. Kumagai, K. Nozaki, Yuji Matsuda

We report a first experimental evidence that a vortex in the high temperature superconductors (HTSC) traps a finite electric charge from the high resolution measurements of the nuclear quadrupole frequencies. In slightly overdoped YBa_2Cu_3O_7 the vortex is negatively charged by trapping electrons, while in underdoped YBa_2Cu_4O_8 it is positively charged by

Yunbo Zhang, H. J. W. Müller-Kirsten

A new method is used to investigate the tunneling between two weakly-linked Bose-Einstein condensates confined in double-well potential traps. The nonlinear interaction between the atoms in each well contributes to a finite chemical potential, which, with consideration of periodic instantons, leads to a remarkably high tunneling frequency. This result can be

K. Takahashi, M. Watanabe, K. Sato

The Earth effects on the energy spectra of supernova neutrinos are studied. We analyze numerically the time-integrated energy spectra of neutrino in a mantle-core-mantle step function model of the Earth&#39;s matter density profile. We consider a realistic frame-work in which there are three active neutrinos whose mass squared differences and mixings are con

Yosuke Imamura

We show that N=2 supersymmetric Maxwell-Chern-Simons-Higgs systems in three dimension can be realized as gauge theories on a D2-brane in D8-branes background with a non-zero B-field. We reproduce a potential of Coulomb branch of the Chern-Simons theory as a potential of a D2-brane in a classical D8-brane solution and show that each Coulomb vacuum is realized

Ranjini Bandyopadhyay, A. K. Sood

We report the observation of dynamical behaviour in dilute, aqueous solutions of a surfactant CTAT (cetyl trimethylammonium p-toluenesulphonate), below the overlap concentration c$^{\star}$. At these concentrations, CTAT forms cylindrical micelles and shows a pronounced shear thickening transition above a concentration-dependent critical shear rate $\dotγ_{c

Robert M. Kerr

It is shown using three series of Rayleigh number simulations of varying aspect ratio AR and Prandtl number Pr that the normalized dissipation at the wall, while significantly greater than 1, approaches a constant dependent upon AR and Pr. It is also found that the peak velocity, not the mean square velocity, obeys the experimental scaling of Ra^{0.5}. The s

Yasushi Ishii, Takeo Fujiwara

Cohesion mechanism of cubic approximant crystals of newly discovered binary quasicrystals, Cd$_6$M (M=Yb and Ca), are studied theoretically. It is found that stabilization due to alloying is obtained if M is an element with low-lying unoccupied $d$ states. This leads to conclusion that the cohesion of the Cd-based compounds is due to the hybridization of the

Michael Trott

We will describe how a new, quite simple, but highly effective algorithm, together with the asymptotically fast FFT-based high-precision number multiplication of Mathematica 4 can calculate the ground state of the x^4 anharmonic oscillator to the new record of more than 1000 digits.

G. de A. Marques, Claudio Furtado, V. B. Bezerra, Fernando Moraes

We study the Landau levels associated with electrons moving in a magnetic field in the presence of a continuous distribution of disclinations, a magnetic screw dislocation and a dispiration. We focus on the influence of these topological defects on the spectrum of the electron(or hole) in a magnetic field in the framework of the geometric theory of defects i

Mingjun Shi, Jiangfeng Du

We discuss in this letter Lewenstein-Sanpera (L-S) decomposition for a specific Werner state. Compared with the optimal case, we propose a quasi-optimal one which in the view of concurrence leads to the same entanglement measure for the entangled mixed state discussed. We think that in order to obtain entanglement of given state the optimal L-S decomposition

S. Khlebnikov

A superconducting ring has different sectors of states corresponding to different values of the trapped magnetic flux; this multitude of states can be used for quantum information storage. If a current supporting a nonzero flux is set up in the ring, fluctuations of electromagnetic field will be able to ``detect&#39;&#39; that current and thus cause a loss o

A. Dogariu, A. Kuzmich, L. J. Wang

Anomalous dispersion cannot occur in a transparent passive medium where electromagnetic radiation is being absorbed at all frequencies, as pointed out by Landau and Lifshitz. Here we show, both theoretically and experimentally, that transparent linear anomalous dispersion can occur when a gain doublet is present. Therefore, a superluminal light pulse propaga

R. L. Collins

Newton&#39;s inverse-square law of universal gravitation assumes constant mass. But mass increases with speed and perhaps with gravity. By SR, mass is increased over the rest mass by gamma. Rest mass is here postulated to increase under gravity, by 1/alpha =1+GM/rc^2. We examine the consequences of introducing this changing mass into Newton&#39;s law in flat

P. -G. Reinhard, M. Bender, J. A. Maruhn

We discuss the performance of two widely used nuclear mean-field models, the relativistic mean-field theory (RMF) and the non-relativistic Skyrme-Hartree-Fock approach (SHF), with particular emphasis on the description of superheavy elements (SHE). We provide a short introduction to the SHF and RMF, the relations between these two approaches and the relation

Carsten Greiner

We first discuss, on a no-QGP basis, the two prominent indications of (a) enhanced strangeness production and of (b) anomalous $J/ψ$-suppression: We elaborate in particular on a recent idea of antihyperon production solely by multi-mesonic reactions. As a possible source for an enhanced dissociation of $c \bar{c}$ pairs we summarize the findings within the &

Susan Kurien, Katepalli Sreenivasan

Local isotropy, or the statistical isotropy of small scales, is one of the basic assumptions underlying Kolmogorov&#39;s theory of universality of small-scale turbulent motion. While, until the mid-seventies or so, local isotropy was accepted as a plausible approximation at high enough Reynolds numbers, various empirical observations that have accumulated si

Magnus Johansson

We consider the long-time evolution of weakly perturbed discrete nonlinear Schroedinger breathers. While breather growth can occur through nonlinear interaction with one single initial linear mode, breather decay is found to require excitation of at least two independent modes. All growth and decay processes of lowest order are found to disappear for breathe

Kenji Kajiwara, Masatoshi Noumi, Yasuhiko Yamada

A q-difference analogue of the fourth Painlevé equation is proposed. Its symmetry structure and some particular solutions are investigated.

Shiro Kawabata

Recent advances in submicrometer technology have made it possible to confine the two-dimensional electron gas into high-mobility semi-conductor heterostructures. Such structure with a lattice of electron-depleted circular obstacles are called quantum antidot lattices, or quantum Lorentz gas systems. By using the semiclassical scattering theory, we show that

Victor G. Kac, Alexei Rudakov

Four $\ZZ_+$-bigraded complexes with the action of the exceptional infinite-dimensional Lie superalgebra E(3,6) are constructed. We show that all the images and cokernels and all but three kernels of the differentials are irreducible E(3,6)-modules. This is based on the list of singular vectors and the calculation of homology of these complexes. As a result,

Victor G. Kac, Alexi Rudakov

Recently one of the authors obtained a classification of simple infinite-dimensional Lie superalgebras of vector fields which extends the well-known classification of E. Cartan in the Lie algebra case. The list consists of many series defined by simple equations, and of several exceptional superalgebras, among them E(3,6). In the article we study irreducible

J. Dittrich, V. I. Inozemtsev

It is generally believed that the ground state of the ferromagnetic Heisenberg-Dirac-Van Vleck Hamiltonians acting on s=1/2 spins of a lattice with N sites has the maximal possible value of the total spin S=N/2 and is N+1 times degenerate. We present a rigorous proof of this statement, independent of the lattice dimension and topology.

Th. Guhr, H. Kohler

We extend the recursion formula for matrix Bessel functions, which we obtained previously, to superspace. It is sufficient to do this for the unitary orthosymplectic supergroup. By direct computations, we show that fairly explicit results can be obtained, at least up to dimension $8\times 8$ for the supermatrices. Since we introduce a new technique, we discu

V. V. Belov, A. Yu. Trifonov, A. V. Shapovalov

The general construction of quasi-classically concentrated solutions to the Hartree-type equation, based on the complex WKB-Maslov method, is presented. The formal solutions of the Cauchy problem for this equation, asymptotic in small parameter \h (\h\to0), are constructed with a power accuracy of O(\h^{N/2}), where N is any natural number. In constructing t

John Sheehan

Let G be a finite simple graph with automorphism group A(G). Then a spanning subgraph U of G is a fixing subgraph of G if G contains exactly $| A(G)|/ | A(G) \cap A(U)| $ subgraphs isomorphic to U: the graph G must always contain at least this number. If in addition $A(U) \subseteq A(G)$ then U is a strong fixing subgraph. Fixing subgraphs are important in m