January 2003 arXiv papers — page 8

Jingyi Chen, Jiayu Li

In this article we study the tangent cones at first time singularity of a Lagrangian mean curvature flow. If the initial compact submanifold is Lagrangian and almost calibrated by ReΩin a Calabi-Yau n-fold (M,Ω), and T>0 is the first blow-up time of the mean curvature flow, then the tangent cone of the mean curvature flow at a singular point (X,T) is a stati

Philippe Caldero, Bethany Marsh

Let U^+ be the plus part of the quantized enveloping algebra of a simple Lie algebra and let B^* be the dual canonical basis of U^+. Let b,b' be in B* and suppose that one of the two elements is a q-commuting product of quantum flag minors. We show that b and b' are multiplicative if and only if they q-commute.

Bernhard Hanke, Volker Puppe

We develop a new approach to the pulling back fixed point theorem of W. Browder and use it in order to prove various generalizations of this result.

Delfim F. M. Torres

We obtain a discrete time analog of E. Noether's theorem in Optimal Control, asserting that integrals of motion associated to the discrete time Pontryagin Maximum Principle can be computed from the quasi-invariance properties of the discrete time Lagrangian and discrete time control system. As corollaries, results for first-order and higher-order discret

Katrina Deane Barron

We introduce the notion of N=1 supergeometric vertex operator superalgebra motivated by the worldsheet geometry underlying genus-zero, two-dimensional, holomorphic N=1 superconformal field theory. We then show, assuming the convergence of certain projective factors, that the category of such objects is isomorphic to the category of N=1 Neveu-Schwarz vertex o

M. Fernández, V. Muñoz

We construct examples of non-formal simply connected and compact oriented manifolds of any dimension bigger or equal to 7.

R. Fioresi

We give the definitions of affine algebraic supervariety and affine algebraic group through the functor of points and we relate them to the other definitions present in the literature. We study in detail the algebraic supergroup $SL(m|n)$ and give explicitly the Hopf algebra structure of the algebra representing its functor of points. At the end we give also

Katrina D. Barron

Within the framework of complex supergeometry and motivated by two-dimensional genus-zero holomorphic N=1 superconformal field theory, we define the moduli space of N=1 genus-zero super-Riemann surfaces with oriented and ordered half-infinite tubes, modulo superconformal equivalence. We define a sewing operation on this moduli space which gives rise to the s

Antonio Gatti

Given a Quantum Field Theory, with a particular content of fields and a symmetry associated with them, if one wants to study the evolution of the couplings via a Wilsonian renormalisation group, there is still a freedom on the construction of a flow equation, allowed by scheme independence. In the present thesis, making use of this choice, we first build up

R. de Lima Rodrigues, A. N. Vaidya

The Morse problem is investigated in relativistic quantum mechanics.

D. G. Barci, L. E. Oxman, S. P. Sorella

We introduce a gauge invariant and string independent two-point fermion correlator which is analyzed in the context of the Schwinger model (QED_2). We also derive an effective infrared worldline action for this correlator, thus enabling the computation of its infrared behavior. Finally, we briefly discuss possible perspectives for the string independent corr

Nicolas Couchoud

We review some facts about AdS2xS2 branes in AdS3xS3 with a Neveu-Schwarz background, and consider the case of Ramond-Ramond backgrounds. We compute the spectrum of quadratic fluctuations in the low-energy approximation and discuss the open-string geometry.

Jin Young Kim, Yoonbai Kim, James E. Hetrick

We study small fluctuations of the stringy wormhole solutions of graviton-dilaton-axion system in arbitrary dimensions. We show under O($d$)-symmetric harmonic perturbation that the Euclidean wormhole solutions are unstable in flat space irrespective of dimensions and in anti de Sitter space of $d=3$.

R. de Lima Rodrigues, A. N. Vaidya

The complete energy spectrum for the Dirac oscillator via R-deformed Heisenberg algebra is investigated.

Gabriela Barenboim, Chris Quigg

Neutrino telescopes that measure relative fluxes of ultrahigh-energy $ν_{e}, ν_μ, ν_τ$ can give information about the location and characteristics of sources, about neutrino mixing, and can test for neutrino instability and for departures from CPT invariance in the neutrino sector. We investigate consequences of neutrino mixing for the neutrino flux arriving

Thomas D. Cohen, Richard. F. Lebed

We analyze excited baryon properties via a 1/N_c expansion from two perspectives: as resonances in meson-nucleon scattering, and as single-quark excitations in the context of a simple quark model. For both types of analysis one can derive novel patterns of degeneracy that emerge as N_c --> \infty, and that are shown to be compatible with one another. This he

Raghavan Rangarajan, Jitesh Bhatt

In a series of papers Boyanovsky et al. have studied the evolution of an inflaton with a negative mass squared and a quartic self coupling using the Closed Time Path (CTP) formalism relevant for out-of-equilibrium dynamics. In this paper we comment on various aspects of these works. We first compare their approach to alternate approaches to study inflaton dy

V. Guzey, M. Strikman

Within the impulse approximation, we derive expressions for the amplitude of deeply virtual Compton scattering on spinless nuclei in terms of the generalized parton distributions of the nucleon. As an application, nuclear effects in the beam-charge and single-spin asymmetries are discussed.

J. Orloff, E. Nezri, V. Bertin

We review the prospects of detecting supersymmetric dark matter in the framework of the Constrained Minimal Supersymmetric Standard Model, and compare indirect with direct detection capabilities.

Qingjun Liu, Thomas A. Trainor

Based on Hijing-1.37 simulations, event-wise mean-pt fluctuations in Au-Au collisions at sqrt-sNN = 200 GeV are studied with graphical and numerical methods. This study shows that jets/minijets could represent a substantial source of mean-pt fluctuations, and jet quenching could reduce these fluctuations significantly. Mean-pt fluctuation measurements are a

Yong Zhou

We have investigated the present renormalization prescriptions of Cabibbo-Kobayashi-Maskawa (CKM) matrix. When considering the prescription which is formulated with reference to the case of zero mixing we find it doesn't satisfy the unitary condition of the bare CKM matrix. After added a delicate patch this problem can be solved at one-loop level. In thi

Miguel Alcubierre, Ricardo Becerril, F. Siddhartha Guzman, Tonatiuh Matos

We present an exhaustive analysis of the numerical evolution of the Einstein-Klein-Gordon equations for the case of a real scalar field endowed with a quadratic self-interaction potential. The self-gravitating equilibrium configurations are called oscillatons and are close relatives of boson stars, their complex counterparts. Unlike boson stars, for which th

Masaru Shibata

We report a new implementation for axisymmetric simulation in full general relativity. In this implementation, the Einstein equations are solved using the Nakamura-Shibata formulation with the so-called cartoon method to impose an axisymmetric boundary condition, and the general relativistic hydrodynamic equations are solved using a high-resolution shock-cap

A. V. Minkevich, Yu. G. Vasilevski

Geometric structure of spherically-symmetric space-time in metric-affine gauge theory of gravity is studied. Restrictions on curvature tensor and Bianchi identities are obtained. By using certain simple gravitational Lagrangian the solution of gravitational equations for vacuum spherically-symmetric gravitational field is obtained.

Michael Beeson, Robert Veroff, Larry Wos

This article answers two questions (posed in the literature), each concerning the guaranteed existence of proofs free of double negation. A proof is free of double negation if none of its deduced steps contains a term of the form n(n(t)) for some term t, where n denotes negation. The first question asks for conditions on the hypotheses that, if satisfied, gu

Lauro Lins, Sostenes Lins, Silvio Melo

In this paper we propose a simple and efficient strategy to obtain a data structure generator to accomplish a perfect hash of quite general order restricted multidimensional arrays named {\em phormas}. The constructor of such objects gets two parameters as input: an n-vector a of non negative integers and a boolean function B on the types of order restrictio

X. F. Wang, P. Vasilopoulos

We evaluate the transport coefficients of a two-dimensional electron gas (2DEG) in the presence of a perpendicular magnetic field and of the spin-orbit interaction (SOI) described only by the Rashba term. The SOI mixes the spin-up and spin-down states of neighboring Landau levels into two new, unequally spaced energy branches. The broadened density of states

J. M. North, D. Zipse, N. S. Dalal, E. S. Choi

Resistivity measurements are reported for single crystals of Mn$_{12}$-Acetate and Fe$_8$Br$_8$. Both materials exhibit a semiconductor-like, thermally activated behavior over the 200-300 K range. The activation energy, $E_a$, obtained for Mn$_{12}$-Acetate was 0.37 $\pm$ 0.05 eV, which is to be contrasted with the value of 0.55 eV deduced from the earlier r

Francis Valiquette, Normand Mousseau

We analyze the structure of the energy landscape of a well-relaxed 1000-atom model of amorphous silicon using the activation-relaxation technique (ART nouveau). Generating more than 40,000 events starting from a single minimum, we find that activated mechanisms are local in nature, that they are distributed uniformly throughout the model and that the activat

Guangyu Sun, Rui-Hua Xie, Mark C. Nicklaus

We comment on a recent paper [D. Schultz et al, Phys. REv. Lett. 90, 015501 (2003)]. We argue that a highly systematical investigation is needed to determine the most stable structures of both pristine and N-substituted fullerenes.

Peter Mayer, Ludovic Berthier, Juan P. Garrahan, Peter Sollich

We investigate the relation between two-time, multi-spin, correlation and response functions in the non-equilibrium critical dynamics of Ising models in d=1 and d=2 spatial dimensions. In these non-equilibrium situations, the fluctuation-dissipation theorem (FDT) is not satisfied. We find FDT `violations' qualitatively similar to those reported in variou

Fernando D. Nobre, Constantino Tsallis

A N-sized inertial classical Heisenberg ferromagnet, which consists in a modification of the well-known standard model, where the spins are replaced by classical rotators, is studied in the limit of infinite-range interactions. The usual canonical-ensemble mean-field solution of the inertial classical $n$-vector ferromagnet (for which $n=3$ recovers the part

J. J. Betouras, V. A. Ivanov, F. M. Peeters

We present a model of pressure effects of a two-band superconductor based on a Ginzburg-Landau free energy with two order parameters. The parameters of the theory are pressure as well as temperature dependent. New pressure effects emerge as a result of the competition between the two bands. The theory then is applied to MgB2. We identify two possible scenari

B. Ruffle, M. Foret, E. Courtens, R. Vacher

The linewidth of longitudinal acoustic waves in densified silica glass is obtained by inelastic x-ray scattering. It increases with a high power alpha of the frequency up to a crossover where the waves experience strong scattering. We find that αis at least 4, and probably larger. Resonance and hybridization of acoustic waves with the boson-peak modes seems

Eric Braaten, H. -W. Hammer, M. Kusunoki

In Phys. Rev. Lett. 89, 180401 (2002) [cond-mat/0204504], Kokkelmans and Holland interpret the results of a recent experiment at JILA that demonstrated atom-molecule coherence in a Bose-Einstein condensate. Using a mean-field approximation to a resonance field theory involving an atom condensate and a molecular condensate, they find that the molecular conden

A. V. Chechkin, J. Klafter, I. M. Sokolov

Several classes of physical systems exhibit ultraslow diffusion for which the mean squared displacement at long times grows as a power of the logarithm of time ("strong anomaly") and share the interesting property that the probability distribution of particle's position at long times is a double-sided exponential. We show that such behaviors can

N. S. Skantzos, J. van Mourik, D. Saad

Using the magnetization enumerator method, we evaluate the practical and theoretical limitations of symmetric channels with real outputs. Results are presented for several regular Gallager code constructions.

Masaru Onoda, Naoto Nagaosa

We study the effect of disorder on the anomalous Hall effect (AHE) in two-dimensional ferromagnets. The topological nature of AHE leads to the integer quantum Hall effect from a metal, i.e., the quantization of $σ_{xy}$ induced by the localization except for the few extended states carrying Chern number. Extensive numerical study on a model reveals that Prui

R. Meester, F. Redig, D. Znamenski

We give a simple rigourous treatment of the classical results of the abelian sandpile model. Although we treat results which are well-known in the physics literature, in many cases we did not find complete proofs in the literature. The paper tries to fill the gap between the mathematics and the physics literature on this subject, and also presents some new p

R. Meester, D. Znamenski

Consider the following evolution model, proposed in \cite{BS} by Bak and Sneppen. Put $N$ vertices on a circle, spaced evenly. Each vertex represents a certain species. We associate with each vertex a random variable, representing the `state' or `fitness' of the species, with values in $[0,1]$. The dynamics proceeds as follows. Every discrete time st

R. Meester, D. Znamenski

One of the key problems related to the Bak-Sneppen evolution model on the circle is to compute the limit distribution of the fitness at a fixed observation vertex in the stationary regime, as the size of the system tends to infinity. Simulations in \cite{J} and \cite{B} suggest that this limit distribution is uniform on $(f,1)$, for some $f\sim2/3$. In this

Z. V. Popovic, M. J. Konstantinovic, V. V. Moshchalkov, M. Isobe

Polarized Raman spectra of the calcium vanadium oxide bronze beta-Ca0.33V2O5 are measured in the temperature range between 300 K and 20 K. The charge ordering phase transition at about 150 K is characterized by the appearance of the new Raman-active modes in the spectra, and by anomalies in the electronic background scattering. The high temperature Raman sca

C. W. J. Beenakker, M. Kindermann, Yu. V. Nazarov

Poisson statistics predicts that the shot noise in a tunnel junction has a temperature independent third cumulant e^2\I, determined solely by the mean current I. Experimental data, however, show a puzzling temperature dependence. We demonstrate theoretically that the third cumulant becomes strongly temperature dependent and may even change sign as a result o

A. Parmeggiani, T. Franosch, E. Frey

We study a one-dimensional totally asymmetric exclusion process with random particle attachments and detachments in the bulk. The resulting dynamics leads to unexpected stationary regimes for large but finite systems. Such regimes are characterized by a phase coexistence of low and high density regions separated by domain walls. We use a mean-field approach

L. Santos, G. V. Shlyapnikov, M. Lewenstein

We find that pancake dipolar condensates can exhibit a roton-maxon character of the excitation spectrum, so far only observed in superfluid helium. We also obtain a condition for the dynamical stability of these condensates. The spectrum and the border of instability are tunable by varying the particle density and/or the confining potential. This opens wide

V. Eisler, Z. Racz, F. van Wijland

The zero-temperature transverse Ising chain carrying an energy flux j_E is studied with the aim of determining the nonequilibrium distribution functions, P(M_z) and P(M_x), of its transverse and longitudinal magnetizations, respectively. An exact calculation reveals that P(M_z) is a Gaussian both at j_E=0 and j_E not equal 0, and the width of the distributio

S. V. Ghaisas

A method based on the kinetics of adatoms on a growing surface under epitaxial growth at low temperature in (1+1) dimensions is proposed to obtain a closed form of local growth equation. It can be generalized to any growth problem as long as diffusion of adatoms govern the surface morphology. The method can be easily extended to higher dimensions. The kineti

E. Olive, J. C. Soret, P. Le Doussal, T. Giamarchi

We present 3D numerical simulation results of moving vortex lattices in presence of 1D correlated disorder at zero temperature. Our results with field tilting confirm the theoritical predictions of a moving Bose glass phase, characterized by transverse pinning and dynamical transverse Meissner effect, the moving flux lines being localized along the correlate

Rajesh K. Murarka, Sarika Bhattacharyya, Biman Bagchi

We study diffusion of small light particles in a solvent which consists of large heavy particles. The intermolecular interactions are chosen to approximately mimic a water-sucrose (or water-polysaccharide) mixture. Both computer simulation and mode coupling theoretical (MCT) calculations have been performed for a solvent-to-solute size ratio five and for a l

Iwan Jensen

We have developed a parallel algorithm that allows us to enumerate the number of self-avoiding polygons on the square lattice to perimeter length 110. We have also extended the series for the first 10 area-weighted moments and the radius of gyration to 100. Analysis of the resulting series yields very accurate estimates of the connective constant $μ=2.638158

Alberto Rosso, Werner Krauth, Pierre Le Doussal, Jean Vannimenus

We compute the probability distribution of the interface width at the depinning threshold, using recent powerful algorithms. It confirms the universality classes found previously. In all cases, the distribution is surprisingly well approximated by a generalized Gaussian theory of independant modes which decay with a characteristic propagator G(q)=1/q^(d+2 ze

Adriaan M. J. Schakel

The perturbative calculation of the effect of fluctuations in the nonzero frequency modes of a weakly interacting Bose gas on the condensation temperature is reviewed. These dynamic modes, discarded in most of the recent studies, have a temperature-induced energy gap that allows for a perturbative approach. The simple, yet powerful algorithm used to calculat

Jaan Kalda

New fractal subset of a rough surface, the ``oceanic coastline&#39;&#39;, is defined. For random Gaussian surfaces with negative Hurst exponent $H<0$, ``oceanic coastlines&#39;&#39; are mapped to the percolation clusters of the (correlated) percolation problem. In the case of rough self-affine surfaces ($H \ge 0$), the fractal dimension of the ``oceanic coas

V. A. Ivanov, J. J. Betouras, F. M. Peeters

We present a Ginzburg-Landau theory for a two-band superconductor with emphasis on MgB$_{2}$. Experiments are proposed which lead to identification of the possible scenarios: whether both $σ$- and $π$-bands superconduct or $σ$% -alone. According to the second scenario a microscopic theory of superconducting MgB$_{2}$ is proposed based on the strongly interac

Anand Sivaramakrishnan, James P. Lloyd, Philip E. Hodge, Bruce A. Macintosh

The useful dynamic range of an image in the diffraction limited regime is usually limited by speckles caused by residual phase errors in the optical system forming the image. The technique of speckle decorrelation involves introducing many independent realizations of additional phase error into a wavefront during one speckle lifetime, changing the instantane

Roger W. Romani, C. -Y. Ng

We find evidence for a faint wind nebula surrounding PSR J0538+2817 in CXO-ACIS imaging. This object is particularly interesting, as the pulsar spindown age is largest for any such X-ray PWN. If interpreted as an equatorial torus, the PWN supports the claimed association with the S147 supernova remnant and implies good alignment between the pulsar spin and s

Rafal M. Nowakowski, Wojciech A. Dziembowski

We show that in evolved stars, even at relatively low surface amplitudes, nonradial modes become strongly nonlinear in the hydrogen shell source, where the Brunt-Vaisala frequency has its absolute maximum. The measure of nonlinearity is the product of horizontal displacement times the radial wavenumber. It becomes large already in evolved delta-Scuti stars.

C. M. Bridge, Mark Cropper, Gavin Ramsay, J. H. J de Bruijne

We present the first high time resolution light curves for six eclipses of the magnetic cataclysmic variable EP Dra, taken using the superconducting tunnel junction imager S-Cam2. The system shows a varying eclipse profile between consecutive eclipses over the two nights of observation. We attribute the variable stream eclipse after accretion region ingress

A. Tej, A. Lançon, M. Scholz

Dynamic models of M-type Mira variables predict the occurrence of water &#34;shells&#34;, i.e. of zones of high H2O density and high H2O absorption inside the stellar atmosphere. The density, position and width of these shells is closely correlated with different types of two-component shapes of the intensity distribution on the disk in the H, K and L near-c

Markus Samland, Ortwin Gerhard

We present a dynamical model for the formation and evolution of a massive disk galaxy, within a growing dark halo whose mass evolves according to cosmological simulations of structure formation. The galactic evolution is simulated with a new 3D chemo-dynamical code, including dark matter, stars and a multi-phase ISM. The simulations start at redshift z=4.85

W. F. Winters, S. A. Balbus, J. F. Hawley

Chaotic flow is studied in a series of numerical magnetohydrodynamical simulations that use the shearing box formalism. This mimics important features of local accretion disk dynamics. The magnetorotational instability gives rise to flow turbulence, and quantitative chaos parameters, such as the largest Lyapunov exponent, can be measured. Linear growth rates

R. Morganti, T. Oosterloo, C. Tadhunter, B. Emonts

We present the first results of a study aimed to detect large HI structures in radio galaxies. In two of the three cases presented (Coma A and B2 0648+27), the detection of a large amount of HI distributed over several tens of kpc suggests a major merger as origin of the observed system and allows to infer when this merger must have occurred. The situation i

Andreja Gomboc

Stellar rotation influences our understanding of stellar structure and evolution, binary systems, clusters etc. and therefore the benefits of a large and highly accurate database on stellar rotation, obtained by GAIA, will be manifold. To study the prospects of GAIA measurement of projected rotational velocities v_rot sin i, we use synthetic stellar spectra

R. Vio, J. G. Nagy, L. Tenorio, P. Andreani

Digital deblurring of images is an important problem that arises in multifrequency observations of the Cosmic Microwave Background (CMB) where, because of the width of the point spread functions (PSF), maps at different frequencies suffer a different loss of spatial resolution. Deblurring is useful for various reasons: first, it helps to restore high frequen

Henry Lee, Eva K. Grebel, Paul Hodge

The results of optical spectroscopy of H II regions in a sample of southern dwarf irregulars consisting of five dwarf galaxies in the Centaurus A group, four dwarfs in the Sculptor group, and eight additional dwarf galaxies are presented. Oxygen abundances are derived using the direct method where [O III]4363 is detected; otherwise, abundances are derived wi

B. H. P. Chan, D. A. Mitchell, L. E. Cram

Archetypal analysis represents each individual member of a set of data vectors as a mixture (a constrained linear combination) of the pure types or archetypes of the data set. The archetypes are themselves required to be mixtures of the data vectors. Archetypal analysis may be particularly useful in analysing data sets comprising galaxy spectra, since each s

Louise M. Griffiths, Charles H. Lineweaver

Under the assumption that the concordance Lambda cold dark matter (CDM) model is the correct model, we test the cosmic microwave background (CMB) anisotropy data for systematic effects by examining the band pass temperature residuals with respect to this model. Residuals are plotted as a function of l, galactic latitude, frequency, calibration source, instru

Izumi Hachisu, Mariko Kato

We have found a new clue to the transition mechanism between optical high/X-ray off and optical low/X-ray on states of the LMC supersoft X-ray source RX J0513.9-6951. A sharp ~1 mag drop is common to the CI Aql 2000 outburst. These drops are naturally attributed to cessation of optically thick winds on white dwarfs. A detailed light-curve analysis of CI Aql

Geoffrey C. Clayton, Michael J. Wolff, Ulysses J. Sofia, K. D. Gordon

Employing the Maximum Entropy Method algorithm, we fit interstellar extinction measurements which span the wavelength range 0.125-3 micron. We present a uniform set of MEM model fits, all using the same grain materials, optical constants and abundance constraints. In addition, we are taking advantage of improved UV and IR data and better estimates of the gas

J. A. Combi, G. E. Romero, J. M. Paredes, D. F. Torres

We report the discovery of a new radio galaxy within the location error box of the gamma-ray source 3EG J1735-1500. The galaxy is a double-sided jet source forming a large angle with the line of sight. Optical observations reveal a V ~ 18 magnitude galaxy at the position of the radio core. Although the association with the EGRET source is not confirmed at th

Rob P. Olling, Walter Dehnen

The Oort constants describe the local variations of the stellar streaming field. Classically, they are determined from stellar proper motions. We discuss problems arising in this procedure. A large, hitherto overlooked, source of systematic error arises from longitudinal variations of the mean stellar parallax. Together with the solar reflex motion, these va

Nancy Remage Evans, Frederick D. Seward, Miriam I. Krauss, Takashi Isobe

The region around the $η$ Car nebula has three OB associations, which contain a Wolf-Rayet star and several massive O3 stars. An early Chandra ACIS-I image was centered on $η$ Car and includes Trumpler 16 and part of Trumpler 14. The Chandra image confirms the well-known result that O and very early B stars are X-ray sources with L$_X$ $\simeq$ 10$^{-7} \tim

C. Bernard, T. Burch, C. DeTar, Steven Gottlieb

We report on a lattice determination of the mass of the exotic $1^{-+}$ hybrid meson using an improved Kogut-Susskind action. Results from both quenched and dynamical quark simulations are presented. We also compare with earlier results using Wilson quarks at heavier quark masses. The results on lattices with three flavors of dynamical quarks show effects of

R. MacKenzie, M. -A. Vachon, U. F. Wichoski

The interaction energy and force between widely separated strings is analyzed in a field theory having applications to superconducting cosmic strings, the SO(5) model of high-temperature superconductivity, and solitons in nonlinear optics. The field theory has two order parameters, one of which is broken in the vacuum (giving rise to strings), the other of w

V. Kiryukhin, T. Y. Koo, H. Ishibashi, J. P. Hill

We report x-ray scattering studies of nanoscale structural correlations in the paramagnetic phases of the perovskite manganites La$_{0.75}$(Ca$_{0.45}$Sr$_{0.55}$)$_{0.25}$MnO$_3$, La$_{0.625}$Sr$_{0.375}$MnO$_3$, and Nd$_{0.45}$Sr$_{0.55}$MnO$_3$. We find that these correlations are present in the orthorhombic $O$ phase in La$_{0.75}$(Ca$_{0.45}$Sr$_{0.55}$

G. C. Levine, V. N. Muthukumar

We solve a model of a qubit strongly coupled to a massive environmental oscillator mode where the qubit backaction is treated exactly. Using a Ginzburg-Landau formalism, we derive an effective action for this well known localization transition. An entangled state emerges as an instanton in the collective qubit-environment degree of freedom and the resulting

Massimo Ostilli

We present a novel approach to Gaussian Berezin correlation functions. A formula well known in the literature expresses these quantities in terms of submatrices of the inverse matrix appearing in the Gaussian action. By using a recently proposed method to calculate Berezin integrals as an expectation of suitable functionals of Poisson processes, we obtain an

K. Aryanpour, Th. A. Maier, M. Jarrell

We are commenting on the article Phys. Rev. {\bf B 65}, 155112 (2002) by G. Biroli and G. Kotliar in which they make a comparison between two cluster techniques, the {\it Cellular Dynamical Mean Field Theory} (CDMFT) and the {\it Dynamical Cluster Approximation} (DCA). Based upon an incorrect implementation of the DCA technique in their work, they conclude t

C. N. Leung, Yvonne Y. Y. Wong

We study the effects of violation of the equivalence principle (VEP) or violation of Lorentz invariance (LIV) in the neutrino sector on the asymmetry between T-conjugate oscillation probabilities, $ΔP_T \equiv P(ν_α \to ν_β) - P(ν_β \to ν_α)$, in a three-flavour framework. We find that additional mixing due to these mechanisms, while obeying all present boun

Patrick B. Hall, Damien Hutsemekers, S. F. Anderson, J. Brinkmann

We study high-resolution spectra of the `overlapping-trough&#39; low-ionization broad absorption line (LoBAL) quasar SDSS J030000.56+004828.0. The CaII, MgII and MgI column densities in this object are the largest reported to date for any BAL outflow. The broad CaII absorption is mildly blended, but the blending can be disentangled to measure the CaII column

A. Sills, S. Deiters, P. Eggleton, M. Freitag

This is a summary paper of MODEST-2, a workshop held at the Astronomical Institute ``Anton Pannekoek&#39;&#39; in Amsterdam, 16-17 December 2002. MODEST is a loose collaboration of people interested in MOdelling DEnse STellar systems, particularly those interested in modelling these systems using all the available physics (stellar dynamics, stellar evolution

Gianluca Grignani, Marta Orselli, Gordon W. Semenoff, Diego Trancanelli

The thermodynamics of type IIB superstring theory in the maximally supersymmetric plane wave background is studied. We compute the thermodynamic partition function for non-interacting strings exactly and the result differs slightly from previous computations. We clarify some of the issues related to the Hagedorn temperature in the limits of small and large c

R. Petronzio, S. Simula, G. Ricco

Recent experimental determinations of the Nachtmann moments of the inelastic structure function of the proton F2p(x, Q**2), obtained at Jefferson Lab, are analyzed for values of the squared four-momentum transfer Q**2 ranging from ~ 0.1 to ~ 2 (GeV/c)**2. It is shown that such inelastic proton data exhibit a new type of scaling behavior and that the resultin

Ji-Feng Yang, Jie Zhou, Chen Wu

The sunset diagram of $λϕ^4$ theory is evaluated numerically in cutoff scheme and a nonzero finite term (in accordance with dimensional regularization (DR) result) is found in contrast to published calculations. This finding dramatically reduces the critical couplings for symmetry breaking in the two loop effective potential discussed in our previous work.

Douglas R. Niven, Robert A. Smith

We evaluate the electron-electron interaction corrections to the electronic thermal conductivity in a disordered conductor in the diffusive regime. We use a diagrammatic many-body method analogous to that of Altshuler and Aronov for the electrical conductivity. We derive results in one, two and three dimensions for both the singlet and triplet channels, and

E. Rollinde, P. Boisse, S. R. Federman, K. Pan

We present spectroscopic observations of the runaway reddened star HD 34078 acquired during the last three years at Observatoire de Haute Provence and McDonald Observatory as well as other spectra obtained since 1990. The drift of the line of sight through the foreground cloud due to the large transverse velocity of HD 34078 allows us to probe the spatial di

M. Osipenko, G. Ricco, M. Taiuti, M. Ripani

We measured the inclusive electron-proton cross section in the nucleon resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2 with the CLAS detector. The large acceptance of CLAS allowed for the first time the measurement of the cross section in a large, contiguous two-dimensional range of Q**2 and x, making it possible to perform an

Mikolaj Korzynski, Jerzy Lewandowski

The goal of this paper is to express the Bach tensor of a four dimensional conformal geometry of an arbitrary signature by the Cartan normal conformal (CNC) connection. We show that the Bach tensor can be identified with the Yang-Mills current of the connection. It follows from that result that a conformal geometry whose CNC connection is reducible in an app

Jos Gheerardyn, Bert Janssen

In this letter we consider what happens to an M2-brane probe when Minkowski space is dimensionally reduced to a fluxbrane solution of IIA supergravity. Given that fluxbrane reductions generally break supersymmetry, we look at how supersymmetry is realised on the D2-brane probe after dualisation. We also show how to extend this to more general non-linear sigm

C. P. Haines, L. E. Campusano, R. G. Clowes

We report the finding of two large-scale structures of galaxies in a 40&#39;x35&#39; field embedded in a 25deg^2 area where two 100 Mpc-scale structures of quasars and MgII absorbers at z~0.8 and z~1.2 have been previously detected. Using deep optical (V- and I-band) imaging, we are able to select high-redshift (0.5<z<1.3) early-type galaxies as those redder

Ulf H. Danielsson

In this paper the relevance of holographic entropy bounds in the context of inflation is investigated. We distinguish between entropy on large and small scales and confront the entropy of quantum fluctuations in an inflating cosmology with the appropriate entropy bounds. In conclusion we do not find any constraints on inflation from holography, but some sugg

Jihn E. Kim

It is argued that a phenomenologically viable grand unification model from superstring is $SU(3)^3$, the simplest gauge group among the grand unifications of the electroweak hypercharge embedded in semi-simple groups. We construct a realistic 4D $SU(3)^3$ model with the GUT scale $\sin^2θ_W^0= \frac38$ in a $Z_3$ orbifold with Wilson line(s). By two GUT scal

D. Reisinger, M. Schonecke, T. Brenninger, M. Opel

Epitaxy of oxide materials on silicon (Si) substrates is of great interest for future functional devices using the large variety of physical properties of the oxides as ferroelectricity, ferromagnetism, or superconductivity. Recently, materials with high spin polarization of the charge carriers have become interesting for semiconductor-oxide hybrid devices i

Esther Galina, Aroldo Kaplan, Linda Saal

The infinite dimensional Clifford Algebra has a maze of irreducible unitary representations. Here we determine their type -real, complex or quaternionic. Some, related to the Fermi-Fock representations, have no real or quetrnionic structures. But there are many on L(2) of the circle that do and which seem to have analytic meaning.

Holger Baumgardt, Junichiro Makino, Piet Hut, Steve McMillan

We present a comparison between the observational data on the kinematical structure of G1 in M31, obtained with the Hubble WFPC2 and STIS instruments, and the results of dynamical simulations carried out using the special-purpose computer GRAPE-6. We have obtained good fits for models starting with single cluster King-model initial conditions and even better

Akira Ishida, Shozo Uehara

We investigate the spatially inhomogeneous decay of an unstable D-brane and construct an asymptotic solution which describes a codimension one D-brane and the tachyon matter in boundary string field theory. In this solution, the tachyon matter exists around the lower-dimensional D-brane.

Tomas Novotny, Andrea Donarini, Antti-Pekka Jauho

We present a quantum theory of the shuttle instability in electronic transport through a nanostructure with a mechanical degree of freedom. A phase space formulation in terms of the Wigner function allows us to identify a cross-over from the tunnelling to the shuttling regime, thus extending the previously found classical results to the quantum domain. Furth

J. Wentz, I. M. Brancus, A. Bercuci, D. Heck

The fluxes of atmospheric muons and neutrinos are calculated by a three dimensional Monte Carlo simulation with the air shower code CORSIKA using the hadronic interaction models DPMJET, VENUS, GHEISHA, and UrQMD. For the simulation of low energy primary particles the original CORSIKA has been extended by a parametrization of the solar modulation and a micros

R. Franco, M. S Figueira, M. E Foglio

We study the specific dependence of the periodic Anderson Model (PAM) in the limit of $U=\infty$ employing the X-boson treatment in two fifferent regimes of the PAM: the heavy fermion Kondo (HF-K) and the heavy fermion local magnetic regime (HF-LMM). We obtain a multiple peak structure for the specific heat in agreement with experimental results as well as t

Josep M. Pons, Pere Talavera

We study semi-classically the dynamics of string solitons in the Maldacena-Nunez background, dual in the infra-red to N=1, d=4 SYM. For closed string configurations rotating in the S^2 x R space wrapped by the stack of N D-branes we find a behavior that indicates the decoupling of the stringy Kaluza-Klein modes with sufficiently large SO(3) quantum numbers.