February 1999 arXiv papers — page 13

D. Bacon, D. A. Lidar, K. B. Whaley

It was shown recently [D.A. Lidar et al., Phys. Rev. Lett. 81, 2594 (1998)] that within the framework of the semigroup Markovian master equation, decoherence-free (DF) subspaces exist which are stable to first order in time to a perturbation. Here this result is extended to the non-Markovian regime and generalized. In particular, it is shown that within both

Shailesh Chandrasekharan, Uwe-Jens Wiese

We present a general strategy to solve the notorious fermion sign problem using cluster algorithms. The method applies to various systems in the Hubbard model family as well as to relativistic fermions. Here it is illustrated for non-relativistic lattice fermions. A configuration of fermion world-lines is decomposed into clusters that contribute independentl

Philip Pearle

A finite relativistic model for free particles, which describes the collapse of the statevector, is presented.

Piotr Kochanski, Krzysztof Wodkiewicz

An operational time of arrival is introduced using a realistic position and momentum measurement scheme. The phase space measurement involves the dynamics of a quantum particle probed by a measuring device. For such a measurement an operational positive operator valued measure in phase space is introduced and investigated. In such an operational formalism a

Ting Yu, Lajos Diósi, Nicolas Gisin, Walter T. Strunz

We present a perturbation theory for non-Markovian quantum state diffusion (QSD), the theory of diffusive quantum trajectories for open systems in a bosonic environment [Physical Review {\bf A 58}, 1699, (1998)]. We establish a systematic expansion in the ratio between the environmental correlation time and the typical system time scale. The leading order re

K. Jacobs, I. Tittonen, H. M. Wiseman, S. Schiller

We perform a quantum theoretical calculation of the noise power spectrum for a phase measurement of the light output from a coherently driven optical cavity with a freely moving rear mirror. We examine how the noise resulting from the quantum back action appears among the various contributions from other noise sources. We do not assume an ideal (homodyne) ph

Krishna Rai Dastidar, Ratan Kumar Das

We have theoretically studied the effect of dissociative autoionization on the photoelectron energy spectrum in (1+2)-photon above threshold ionization(ATI) of H2 molecules. We have considered excitation from the ground state X-singlet-Sigma-g+(v=0,j) to the doubly excited autoionizing states of singlet-Sigma-u+ and singlet-Pi-u+ symmetry, via the intermedia

B. Hegedus, A. Czirok, I. Fazekas, T. Babel

Long-term videomicroscopy and computer-aided statistical analysis were used to determine some characteristic parameters of in vitro cell motility and proliferation in three established cell lines derived from human glioblastoma tumors. Migration and proliferation activities were compared among the three cell lines since these are two features of tumor cells

V. S. Timoteo, C. L. Lima

We obtain a q-deformed algebra version of the Nambu-Jona-Lasinio model gap equation. In this framework we discuss some hadronic properties such as the dynamical mass generated for the quarks, the pion decay constant and the phase transition present in this model.

The LUNA Collaboration, R. Bonetti, C. Broggini, L. Campajola

We give the LUNA results on the cross section measurement of a key reaction of the proton-proton chain strongly affecting the calculated neutrino luminosity from the Sun: He3+He3-->He4+2p. Due to the cosmic ray suppression provided by the Gran Sasso underground laboratory it has been possible to measure the cross section down to the lower edge of the solar G

A. Voros

Stationary 1D Schrödinger equations with polynomial potentials are reduced to explicit countable closed systems of exact quantization conditions, which are selfconsistent constraints upon the zeros of zeta-regularized spectral determinants, complementing the usual asymptotic (Bohr--Sommerfeld) constraints. (This reduction is currently completed under a certa

Tatiana A. Ivanova

We discuss the twistor correspondence between complex vector bundles over a self-dual four-dimensional manifold and holomorphic bundles over its twistor space and describe the moduli space of self-dual Yang-Mills fields in terms of Cech and Dolbeault cohomology sets. The cohomological description provides the geometric interpretation of symmetries of the sel

Goro Hatayama, Yoshiyuki Koga, Atsuo Kuniba, Masato Okado

We consider a category of finite crystals of a quantum affine algebra whose objects are not necessarily perfect, and set of paths, semi-infinite tensor product of an object of this category with a certain boundary condition. It is shown that the set of paths is isomorphic to a direct sum of infinitely many, in general, crystals of integrable highest weight m

A. Leclair, G. Mussardo

Finite temperature correlation functions in integrable quantum field theories are formulated only in terms of the usual, temperature-independent form factors, and certain thermodynamic filling fractions which are determined from the thermodynamic Bethe ansatz. Explicit expressions are given for the one and two-point functions.

Costas Kounnas

Using the properties of gauged N=4 supergravity, we show that it is possible to derive a universal thermal effective potential that describes all possible high-temperature instabilities of the known N=4 superstrings. These instabilities are due to non-perturbative dyonic modes, which become tachyonic in a region of the thermal moduli space M={s,t,u}; M is co

M. Sakamoto, M. Tachibana, K. Takenaga

We propose a new spontaneous supersymmetry breaking mechanism, in which extra compact dimensions play an important role. To illustrate our mechanism, we study a simple model consisting of two chiral superfields, where one spatial dimension is compactified on a circle $S^1$. It is shown that supersymmetry is spontaneously broken irrespective of the radius of

M. Sakamoto, M. Tachibana, K. Takenaga

We propose a mechanism to break the translational invariance of compactified space spontaneously. As a simple model, we study a real $ϕ^4$ model compactified on $M^{D-1}\otimes S^1$ in detail, where we impose a nontrivial boundary condition on $ϕ$ for the $S^1$-direction. It is shown that the translational invariance for the $S^1$-direction is spontaneously

Csaba Csaki, Jorge Russo, Konstadinos Sfetsos, John Terning

The most general black M5-brane solution of eleven-dimensional supergravity (with a flat R^4 spacetime in the brane and a regular horizon) is characterized by charge, mass and two angular momenta. We use this metric to construct general dual models of large-N QCD (at strong coupling) that depend on two free parameters. The mass spectrum of scalar particles i

Mikhail Z. Iofa, Leopoldo A. Pando Zayas

We discuss a magnetic black-hole solution to the equations of motion of the string-loop-corrected effective action. At the string-tree level, this solution is the extremal magnetic black hole described by the "chiral null model." In the extremal case, the string-loop correction is constant, and this fact is used to analytically solve the loop-correct

D. Zeppenfeld

These lectures are intended as a pedagogical introduction to physics at $e^+e^-$ and hadron colliders. A selection of processes is used to illustrate the strengths and capabilities of the different machines. The discussion includes $W$ pair production and chargino searches at $e^+e^-$ colliders, Drell-Yan events and the top quark search at the Tevatron, and

S. J. Huber, M. G. Schmidt

The hot electroweak potential for small Higgs field values is argued to obtain contributions from a fluctuating gauge field background leading to confinement. The destabilization of F^2=0 and the crossover are discussed in our phenomenological approach, also based on lattice data.

K. Odagiri

It has recently been shown that through the $τν$ decay mode the heavy charged Higgs bosons $H^\pm$ can be discovered at LHC over a vast region of the parameter space previously thought unaccessible. If the charged Higgs bosons are discovered in this decay mode and the measurements of its mass and $\tanβ$ are made, it allows us to make greater use of the domi

G. Lopez Castro, J. L. Lucio M., J. Pestieau

We use SU(3) flavor symmetry to analyze the $PP', VP$ and baryon-antibaryon decays of $J/ψ$. Both, the SU(3)-invariant and -violating contributions are considered. Particular attention is paid to the interference of the electromagnetic and strong amplitudes.

D. P. Roy

After a brief introduction to SUSY I discuss the missing-p_T signature for superparticles from R-parity conservation and the multilepton signature, which follows from their cascade decay. The GUT and SUGRA constraints on the SUSY mass parameters are discussed along with the resulting SUSY signals at LHC. Finally I consider the effect of relaxing the SUGRA co

Kari Enqvist

In D-term inflation models, the fluctuations of squark fields in the flat directions give rise to isocurvature density fluctuations stored in the Affleck-Dine condensate. After the condensate breaks up in B-balls, these can be perturbations in the baryon number, or, in the case where the present neutralino density comes directly from B-ball decay, perturbati

P. Nason, R. Rueckl, M. Spira

We discuss W boson production at HERA including NLO QCD corrections.

Mark E. Hayes, Michael Krämer

We review the theoretical and experimental status of heavy-flavour production at HERA. The results presented include some outstanding issues in charm and beauty photoproduction, charm production in DIS and quarkonium production.

E. Gotsman, E. Levin, U. Maor

The values and energy dependence for the survival probability $< \mid S\mid^2 >$ of large rapidity gaps (LRG) are calculated in a three channel model. This model includes single and double diffractive production, as well as elastic rescattering. It is shown that $< \mid S \mid^2 >$ decreases with increasing energy, in line with recent results for LRG dijet p

Kiwoon Choi, Kyuwan Hwang, Hang Bae Kim, Taekoon Lee

We study the cosmological gravitino production in gauge mediated supersymmetry breaking models, while properly taking into account the existence of the messenger mass scale. It is found that for sizable parameter range of the model the messenger sector contribution leads to more stringent upper bound on the reheat temperature obtained from the condition that

Klaus Geiger

We derive a non-perturbative evolution equation for the gluon propagator in axial gauges based on the framework of Wetterich&#39;s formulation of the exact renormalization group. We obtain asymptotic solutions to this equation in the ultraviolet and infrared limits.

Pervez Hoodbhoy, Wei Lu

By explicit calculation we demonstrate that, in variance with the classical prediction, the leading twist contribution to the exclusive electroproduction of transversely polarized vector mesons from the nucleon does not vanish beyond the leading order in perturbation theory. This appears to be due to a quantum-mechanical anomaly, in the sense that a classica

N. I. Kochelev

It is shown that instantons provide a natural mechanism to explain an unusual azimuthal dependence of the production of the even-parity glueball candidates in central pp collision. A different azimuthal dependence for instanton-induced production of the odd-parity glueballs is predicted.

K. Odagiri

We discuss the search for the heavy charged Higgs bosons H^\pm, implicitly of the Minimal Supersymmetric Standard Model, in the tau-nu decay mode at the LHC. Compared to the dominant decay mode H^\pm\to bt, the channel suffers from suppression due to the branching ratio and the lack of direct mass reconstruction, but the reduced QCD background makes it a fea

Romuald A. Janik, Maciej A. Nowak, Gabor Papp, Ismail Zahed

We model the effects of a large number of zero modes for $N_f$ species of quarks at finite vacuum angle $θ$, using a matrix model with gaussian weights constrained by the topological susceptibility and compressibility. The quenched free energy exhibits a cusp at $θ<π$ that is sensitive to the accuracy of the numerical analysis and the maximum density of wind

Richard J. Tesarek

We present a new charged Higgs search technique using the effects of scalar dynamics in semileptonic meson decay. Applying this method to a modest sample of B meson decays yields sensitivity to the high tan(beta) region well beyond existing charged Higgs searches. We present a new charged Higgs search technique using the effects of scalar dynamics in semilep

Meng Ta-chung, R. Rittel, K. Tabelow, Zhang Yang

The $t$-dependence and the $(M_x^2/s)$-dependence of the double differential cross-sections for inelastic diffractive scattering off proton-target are discussed. Here $t$ stands for the four-momentum-transfer squared, $M_x$ for the missing mass, and $\sqrt{s}$ for the total c.m.s. energy. It is shown, that the space-time properties of the color-singlet gluon

C. Boros, Meng Ta-chung, R. Rittel, Zhang Yang

It is proposed, that color-singlet gluon-clusters can be formed in hadrons as a consequence of self-organized criticality (SOC) in systems of interacting soft gluons, and that the properties of such spatiotemporal complexities can be probed experimentally by examing inelastic diffractive scattering. Theoretical arguments and experimental evidences supporting

A. Duncan, E. Eichten, R. Roskies, H. Thacker

The modelling of the ultraviolet contributions to the quark determinant in lattice QCD in terms of a small number of Wilson loops is examined. Complete Dirac spectra are obtained for sizeable ensembles of SU(3) gauge fields at $β$=5.7 on 6$^4$, 8$^4$, and 10$^4$ lattices allowing for the first time a detailed study of the volume dependence of the effective l

L. Del Debbio, S. J. Hands

We present Monte Carlo simulation results for the three dimensional Thirring model for numbers of fermion flavors N_f=4 and 6. For N_f=4 we find a second order chiral symmetry breaking transition at strong coupling, corresponding to an ultra-violet fixed point of the renormalisation group defining a non-trivial continuum limit. The critical exponents extract

Maxim N. Chernodub, Seikou Kato, Naoki Nakamura, Mikhail I. Polikarpov

We study various representations of infrared effective theory of SU(2) gluodynamics starting from the Abelian monopole action derived recently by numerical calculations in the Maximal Abelian projection. In particular we derive the string model and the dual Abelian-Higgs (dual Ginzburg-Landau) model which corresponds to infrared SU(2) gluodynamics. It occurs

P. Bailly, J. Chauveau, J. F. Genat, J. F. Huppert

A 16-channel digital TDC chip has been built for the DIRC Cherenkov counter of the BaBar experiment at the SLAC B-factory (Stanford, USA). The binning is 0.5 ns, the conversion time 32 ns and the full-scale 32 mus. The data driven architecture integrates channel buffering and selective readout of data falling within a programmable time window. The time measu

L. Baudis, A. Dietz, G. Heusser, H. V. Klapdor-Kleingrothaus

The Heidelberg-Moscow experiment gives the most stringent limit on the Majorana neutrino mass. After 24 kg yr of data with pulse shape measurements, we set a lower limit on the half-life of the neutrinoless double beta decay in 76Ge of T_1/2 > 5.7 * 10^{25} yr at 90% C.L., thus excluding an effective Majorana neutrino mass greater than 0.2 eV. This allows to

Steven J. Yellin

The LSND and KARMEN neutrino oscillation experiments are compared in order to clarify the significance of the apparent disagreement between their results.

Arlen Anderson

Careful analysis of parametrized variational principles in mechanics and field theory leads to a generalization of Einstein theory that includes a cosmological stress tensor. This generalization also follows by restricting variations of the metric in the Hilbert action to spacetime diffeomorphisms. The equation of motion for the generalized theory is the twi

Abel Camacho Quintana

The logical consistency of a description of Quantum Theory in the context of General Relativity, which includes Minimal Coupling Principle, is analyzed from the point of view of Feynman&#39;s formulation in terms of path integrals. We will argue from this standpoint and using an argument that claims the incompleteness of the general-relativistic description

T. R. Mongan

A quantum mechanical model for an N + 1 dimensional universe arising from a quantum fluctuation is outlined. (3 + 1) dimensions are a closed infinitely-expanding universe and the remaining N - 3 dimensions are compact. The (3 + 1) non-compact dimensions are modeled by quantizing a canonical Hamiltonian description of a homogeneous isotropic universe. It is a

Sa-Kwang Song, Sung Hyon Myaeng

In any search-based digital library (DL) systems dealing with a non-trivial number of documents, users are often required to go through a long list of short document descriptions in order to identify what they are looking for. To tackle the problem, a variety of document organization algorithms and/or visualization techniques have been used to guide users in

Ferenc Pazmandi, Gergely Zarand, Gergely T. Zimanyi

We study hysteretic phenomena in random ferromagnets. We argue that the angle dependent magnetostatic (dipolar) terms introduce frustration and long range interactions in these systems. This makes it plausible that the Sherrington - Kirkpatrick model may be able to capture some of the relevant physics of these systems. We use scaling arguments, replica calcu

David H. Cobden, C. H. W. Barnes, C. J. B. Ford

We find that mesoscopic conductance fluctuations in the quantum Hall regime in silicon MOSFETs display simple and striking patterns. The fluctuations fall into distinct groups which move along lines parallel to loci of integer filling factor in the gate voltage-magnetic field plane. Also, a relationship appears between the fluctuations on quantum Hall transi

D. V. Fil

An interaction of a double layer electron system realized in an AlGaAs-GaAs-AlGaAs heterostructure with nonuniform elastic modes localized in the GaAs layer is considered. The dependence of the coupling constant on the ratio between the thickness of the GaAs layer and the wavelength is calculated for the wave vector directed along the [110] axis, the displac

F. G. Mertens, H. -J. Schnitzer, A. R. Bishop

Starting from a travelling wave ansatz we show successively that the shape of a nonlinear excitation generally depends also on the 1st, 2nd, ... time derivative of the position X of the excitation. From the Hamilton equations we derive a hierarchy of equations of motion for X. The type of the excitation determines on which levels the hierarchy can be truncat

Valery I. Rupasov

The low-energy physics of a spin-1/2 Kondo impurity in a gapless host, where a density of band states $ρ_0(ε)=|ε|^r/(|ε|^r+β^r)$ vanishes at the Fermi level $ε=0$, is studied by the Bethe ansatz. The growth of the parameter $Γ_r=β{\rm g}^{-1/r}$ (where ${\rm g}$ is an exchange constant) is shown to drive the system ground state from the Kondo regime with the

M. E. Gouvea, G. M. Wysin, S. A. Leonel, A. S. T. Pires

We apply the self-consistent harmonic approximation (SCHA) to study static and dynamic properties of the two-dimensional classical Heisenberg model with easy-axis anisotropy. The static properties obtained are magnetization and spin wave energy as functions of temperature, and the critical temperature as a function of the easy-axis anisotropy. We also calcul

T. Garel, H. Orland, E. Orlandini

We consider polymers made of magnetic monomers (Ising or Heisenberg-like) in a good solvent. These polymers are modeled as self-avoiding walks on a cubic lattice, and the ferromagnetic interaction between the spins carried by the monomers is short-ranged in space. At low temperature, these polymers undergo a magnetic induced first order collapse transition,

A. Diaz-Sanchez, M. Ortuno, M. Pollak, A. Perez-Garrido

We derive a microscopic expression for the dielectric susceptibility $χ$ of a Coulomb glass, which corresponds to the definition used in classical electrodynamics, the derivative of the polarization with respect to the electric field. The fluctuation-dissipation theorem tells us that $χ$ is a function of the thermal fluctuations of the dipole moment of the s

Y. Gaididei, T. Kamppeter, F. G. Mertens, A. R. Bishop

In the 2-dimensional anisotropic Heisenberg model with XY-symmetry there are non-planar vortices which exhibit a localized structure of the z-components of the spins around the vortex center. We study how thermal noise induces a transition of this structure from one polarization to the opposite one. We describe the vortex core by a discrete Hamiltonian and c

Till Kamppeter, Franz G. Mertens, Esteban Moro, Angel Sanchez

We study how thermal fluctuations affect the dynamics of vortices in the two-dimensional classical, ferromagnetic, anisotropic Heisenberg model depending on their additive or multiplicative character. Using a collective coordinate theory, we analytically show that multiplicative noise, arising from fluctuations in the local field term of the Landau-Lifshitz

John Cardy, Francesca Colaiori

We show that the problem of directed percolation on an arbitrary lattice is equivalent to the problem of m directed random walkers with rather general attractive interactions, when suitably continued to m=0. In 1+1 dimensions, this is dual to a model of interacting steps on a vicinal surface. A similar correspondence with interacting self-avoiding walks is c

P. Capuzzi, E. S. Hernandez

We investigate the collective excitations of a single-species Bose gas at T=0 in a harmonic trap where the confinement undergoes some splitting along one spatial direction. We mostly consider onedimensional potentials consisting of two harmonic wells separated a distance 2 z_0, since they essentially contain all the barrier effects that one may visualize in

I. Luk&#39;yanchuk, A. Jorio, P. Saint-Gregoire

We consider the evolution of the phase transition from the parent hexagonal phase $P6_{3}/mmc$ to the orthorhombic phase $Pmcn$ that occurs in several compounds of $A&#39;A&#39;&#39;BX_{4}$ family as a function of the hcp lattice parameter $c/a$. For compounds of $K_{2}SO_{4}$ type with $c/a$ larger than the threshold value 1.26 the direct first-order transi

R. G. Agostino, M. P. De Santo, G. Liberti, R. Le Pera

A new tecnique for the production of special shaped SPM tips is reported. Noble metal coated tips are produced with flat and circular tip front. The unusual truncated-cone tip shape is obtained by modifying commercial tips. The diameter of the tip front flat area can be varied continuously in the range 0.05 - 1 micrometer.

Urs Ledermann, Alban L. Fauchere, Gianni Blatter

We study the current in a clean superconductor-normal-metal-superconductor junction of length d and width w in the presence of an applied magnetic field H. We show that both the geometrical pattern of the current density and the critical current as a function of the total flux in the junction, depend on the ratio of the Josephson vortex distance a_0 and the

B. Derrida, M. R. Evans

The asymmetric exclusion process on a ring in one-dimension is considered with a single defect particle. The steady state has previously been solved by a matrix product method. Here we use the Bethe ansatz to solve exactly for the long time limit behaviour of the generating function of the distance travelled by the defect particle. This allows us to recover

Oron Zachar

Following the recent NMR experiments by Gorny et al., we discuss the effect of a magnetic field on the superconducting T_c and the spin pseudo-gap T^*. As a testable prediction, we argue that a spin pseudo-gap should also be observed in over-doped samples in a magnetic fied (while normally there is no pseudo-gap above T_c). We find that different theoretical

A. V. Germanenko, V. A. Larionova, G. M. Minkov, S. A. Negashev

The results of computer simulation of particle motion over the plane with randomly distributed scatters are presented. They are used to analyse the influence of scattering anisotropy on the negative magnetoresistance due to weak localisation. It is shown that the magnetic field dependence of magnetoresistance in this case can be described by the well known e

D. R. Garnett, J. R. Walsh, Y. -H. Chu, B. M. Lasker

We report the discovery of small, isolated dust clouds in the Large Magellanic Cloud, which are excellent candidates for counterparts to the Bok globules observed in the Galaxy. We detect these small clouds silhoutted against diffuse H-alpha emission, based on parallel imaging with the WFPC-2 on HST. The clouds we identify as Bok globule candidates have typi

Steven B. Kraemer, Luis C. Ho, D. Michael Crenshaw, Joseph C. Shields

We have combined Hubble Space Telescope/Faint Object Spectrograph, ground-based, and Infrared Space Observatory spectra of the nucleus of NGC 4395, the least luminous and nearest known type 1 Seyfert galaxy. The spectra show emission lines from a wide range of ionization states and critical densities. We have generated multicomponent photoionization models o

Stephane Coutu, Steven W. Barwick, James J. Beatty, Amit Bhattacharyya

Cosmic rays at the Earth include a secondary component originating in collisions of primary particles with the diffuse interstellar gas. The secondary cosmic rays are relatively rare but carry important information on the Galactic propagation of the primary particles. The secondary component includes a small fraction of antimatter particles, positrons and an

S. B. Kraemer, T. J. Turner, D. M. Crenshaw, I. M. George

We explore the effects of UV absorbing material on the shape of the EUV continuum radiation emitted by the active galactic nucleus, and on the relative strengths of emission lines, formed in the narrow line regions of Seyfert galaxies, excited by this continuum. Within a sample of Seyfert 1.5 galaxies, objects with flatter soft X-ray slopes tend to have lowe

P. Morel, A. Baglin

The recent distance determinations by HIPPARCOS have allowed to locate very precisely a reasonable set of subdwarfs in the HR diagram. A detailed comparison with evolutionary models is now possible and it has been recently claimed that the observed lower part of the main-sequence is cooler than the computed one. In this paper we show that microscopic diffusi

K. Iwasawa, S. W. Allen, A. C. Fabian, A. C. Edge

We present results from ASCA and ROSAT HRI observations of the powerful radio galaxy 4C+55.16 at redshift 0.24. Extended soft X-ray emission is imaged by the ROSAT HRI. The X-ray brightness profile is sharply peaked on the radio galaxy, characteristic of a strong cooling flow. The X-ray spectrum obtained from ASCA is consistent with multi-phase intracluster

B. Hnatyk, O. Petruk

We examine the hypothesis that some supernova remnants (SNRs) may be responsible for some unidentified gamma-ray sources detected by EGRET instrument aboard the Compton Gamma Ray Observatory. If this is the case, gamma-rays are produced via pion production and decay from direct inelastic collisions of accelerated by SNR shock wave ultrarelativistic protons w

L. Bergstrom, S. Iguri, H. Rubinstein

We put bounds on the variation of the value of the fine structure constant $α$, at the time of Big Bang nucleosynthesis. We study carefully all light elements up to $^7$Li. We correct a previous upper limit on $|Δα/ α|$ estimated from $^4$He primordial abundance and we find interesting new potential limits (depending on the value of the baryon-to-photon rati

Aylwyn Scally, Cathie Clarke, Mark J. McCaughrean

Using proper motion data for 894 stars in the Orion Nebula Cluster (ONC) compiled by Jones & Walker in 1988, we search for binaries with apparent separations in the range 1000-5000 AU, and find an upper limit of three. Using a Monte Carlo method, we test the consistency of this result with two hypotheses: i) that the cluster contains a binary population iden

HongSheng Zhao

Tremendous progress has been made recently in modelling the morphology and kinematics of centers of galaxies. Increasingly realistic models are built for central bar, bulge, nucleus and black hole of galaxies, including our own. The newly revived Schwarzschild method has played a central role in these theoretical modellings. Here I will highlight some recent

Katrin Reblinsky, Matthias Bartelmann

Selection of galaxy clusters by mass is now possible due to weak gravitational lensing effects. It is an important question then whether this type of selection reduces the projection effects prevalent in optically selected cluster samples. We address this question using simulated data, from which we construct synthetic cluster catalogues both with Abell&#39;

Matthias Bartelmann, Peter Schneider

We demonstrate that the aperture mass as a measure for cosmic shear closely approximates (to better than ~5%) the scaled and shifted power spectrum of the projected mass density. This cosmological weak-lensing information can thus be used to directly infer the projected matter power spectrum with high accuracy. As an application, we show that aperture-mass o

Donald J. Horner, Richard F. Mushotzky, Caleb A. Scharf

We examine the relationship between the mass and x-ray gas temperature of galaxy clusters using data drawn from the literature. Simple theoretical arguments suggest that the mass of a cluster is related to the x-ray temperature as $M \propto T_x^{3/2}$. Virial theorem mass estimates based on cluster galaxy velocity dispersions seem to be accurately described

A. V. Kopylov

When the magnetic moment of neutron m presesses around a static magnetic field B the electric dipole moment of neutron dn is tied up with m and rotates in the plane perpendicular to B with Larmor frequency wp. If to apply the oscillating electric field perpendicular to a field B this may cause a spin flip of a neutron. At w=wp one may observe a resonance sim

Rui Dilao, Tiago Domingos

Based on the law of mass action (and its microscopic foundation) and mass conservation, we present here a method to derive consistent dynamic models for the time evolution of systems with an arbitrary number of species. Equations are derived through a mechanistic description, ensuring that all parameters have ecological meaning. After discussing the biologic

Boris A. Kupershmidt, Ognyan S. Stoyanov

A Poisson-Lie group acting by the coadjoint action on the dual of its Lie algebra induces on it a non-trivial class of quadratic Poisson structures extending the linear Poisson bracket on the coadjoint orbits.

Will Loinaz, T. J. Newman

We consider the revival properties of quantum systems with an eigenspectrum E_{n} proportional to n^{2}, and compare them with the simplest member of this class - the infinite square well. In addition to having perfect revivals at integer multiples of the revival time t_{R}, these systems all enjoy perfect fractional revivals at quarterly intervals of t_{R}.

Subhash Kak

This note presents a method of public key distribution using quantum communication of n photons that simultaneously provides a high probability that the bits have not been tampered. It is a three-state variant of the quantum method of Bennett and Brassard (BB84) where the transmission states have been decreased from 4 to 3 and the detector states have been i

T. Gannon

In 1986 Cappelli, Itzykson and Zuber classified all modular invariant partition functions for the conformal field theories associated to the affine $A_1$ algebra; they found they fall into an A-D-E pattern. Their proof was difficult and attempts to generalise it to the other affine algebras failed -- in hindsight the reason is that their argument ignored mos

Han-Yong Choi, Yunkyu Bang, David K. Campbell

We propose that, if the pseudogap state in the cuprate superconductors can be described in terms of the phase-incoherent preformed pairs, there should exist Andreev reflection from these pairs even above the superconducting transition temperature, $T_c$. After giving qualitative arguments for this effect, we present more quantitative calculations based on th

Julia Kempe

Entanglement between three or more parties exhibits a realm of properties unknown to two-party states. Bipartite states are easily classified using the Schmidt decomposition. The Schmidt coefficients of a bipartite pure state encompass all the non-local properties of the state and can be &#34;seen&#34; by looking at one party&#39;s density matrix only. Pure

H. -W. Hammer, J. N. Ng

We calculate the decay of pionium atoms into two photons. The pion polarizability gives rise to a 10% correction to the corresponding decay width for pointlike pions. This opens the possibility to obtain the difference between the electric and magnetic polarizability of the charged pion from a future measurement of the branching fraction of pionium into two

R. D&#39;hulst, G. J. Rodgers

We investigate different versions of the minority game, a toy model for agents buying and selling a commodity. The Hamming distance between the strategies used by agents to take decisions is introduced as an analytical tool to determine several properties of these models. The success rate of the agents in an adaptive version of the game is compared with the

Alexander K. Hartmann

A huge number of independent true ground-state configurations is calculated for two-, three- and four-dimensional +- J spin-glass models. Using the genetic cluster-exact approximation method, system sizes up to N=20^2,8^3,6^4 spins are treated. A ``ballistic-search&#39;&#39; algorithm is applied which allows even for large system sizes to identify clusters o

S. S. Xulu

In this paper we obtain the energy distribution associated with the Ernst space-time (geometry describing Schwarzschild black hole in Melvin&#39;s magnetic universe) in Einstein&#39;s prescription. The first term is the rest-mass energy of the Schwarzschild black hole, the second term is the classical value for the energy of the uniform magnetic field and th

Steven D. Bass

We review the theory and present status of the proton spin problem with emphasis on the transition between current quarks and constituent quarks in QCD.

R. Marani, M. Artoni

We study how the spectral properties of resonance fluorescence propagate through a two-atom system. Within the weak-driving-field approximation we find that, as we go from one atom to the next, the power spectrum exhibits both sub-natural linewidth narrowing and large asymmetries while the spectrum of squeezing narrows but remains otherwise unchanged. Analyt

Brien C. Nolan

Covariant equations characterizing the strength of a singularity in spherical symmetry are derived and several models are investigated. The difference between central and non-central singularities is emphasised. A slight modification to the definition of singularity strength is suggested. The gravitational weakness of shell crossing singularities in collapsi

G. Bonvicini

We report measurements of the $D^0, D^+$, and $D^+_s$ meson lifetimes using $3.7 fb^{-1}$ of e^+e^- annihilation data collected near the $Υ(4S)$ resonance with the CLEO detector. The lifetimes of the $D^0, D^+$, and $D^+_s$ mesons are measured to be $408.5 \pm 4.1 ^{+3.5}_{-3.4} fs, 1033.6 \pm 22.1 ^{+9.9}_{-12.7} fs$, and $486.3 \pm 15.0 ^{+4.9}_{-5.1} fs$,

A. Dar, R. Plaga

We propose a new hypothesis for the origin of the major part of non-solar hadronic cosmic rays (CRs) at all energies: highly relativistic, narrowly collimated jets from the birth or collapse of neutron stars (NSs) in our Galaxy accelerate ambient disk and halo matter to CR energies and disperse it in hot spots which they form when they stop in the Galactic h

Guifre Vidal

An optimal local conversion strategy between any two pure states of a bipartite system is presented. It is optimal in that the probability of success is the largest achievable if the parties which share the system, and which can communicate classically, are only allowed to act locally on it. The study of optimal local conversions sheds some light on the enta

Kirill Melnikov, Alexander Yelkhovsky

We present a calculation of the O(m alpha^7 ln(alpha)^2) corrections to positronium energy levels. The result is used to estimate the current uncertainty in theoretical predictions of the positronium spectrum.

Sze-Shiang Feng

Some rigorous conclusions of the Hubbard model, Kondo lattice model and periodic Anderson model at finite temperature are acquired employing the fluctuation-dissipation theorem and particle-hole transform. The main conclusion states that for the three models, the expectation value of ${\bf \tilde{S}}^2-{\bf \tilde{S}}^2_z$ will be of order $N_Λ$ at any finit

D. C. Cabra, A. Honecker, P. Pujol

We analyze the phase diagram of a system of spin-1/2 Heisenberg antiferromagnetic chains interacting through a zig-zag coupling, also called zig-zag ladders. Using bosonization techniques we study how a spin-gap or more generally plateaux in magnetization curves arise in different situations. While for coupled XXZ chains, one has to deal with a recently disc

Tetsufumi Tanamoto

A quantum computer based on an asymmetric coupled dot system has been proposed and shown to operate as the controlled-NOT-gate. The basic idea is (1) the electron is localized in one of the asymmetric coupled dots. (2)The electron transfer takes place from one dot to the other when the energy-levels of the coupled dots are set close. (3)The Coulomb interacti