November 2005 arXiv papers — page 6

E. P. van den Ban, H. Schlichtkrull

We show that Arthur's Paley-Wiener theorem for K-finite compactly supported smooth functions on a real reductive Lie group G of the Harish-Chandra class can be deduced from the Paley-Wiener theorem we established in the more general setting of a reductive symmetric space. In addition, we formulate an extension of Arthur's theorem to K-finite compactl

E. Loubeau, R. Pantilie

We show that Weyl spaces provide a natural context for harmonic morphisms.

Chuan-Tsung Chan, Pei-Ming Ho, Jen-Chi Lee, Shunsuke Teraguchi

We identify spacetime symmetry charges of 26D open bosonic string theory from an infinite number of zero-norm states (ZNS) with arbitrary high spin in the old covariant first quantized string spectrum. We give various evidences to support this identification. These include massive sigma-model calculation, Witten string field theory calculation, 2D string the

Gherardo Piacitelli

We discuss the perturbative approach a` la Dyson to a quantum field theory with nonlocal self-interaction :phi*...*phi:, according to Doplicher, Fredenhagen and Roberts (DFR). In particular, we show that the Wick reduction of non locally time--ordered products of Wick monomials can be performed as usual, and we discuss a very simple Dyson diagram.

A. Bouchareb, M. Ramon Medrano, N. G. Sanchez

We compute the quantum string entropy S_s(m, H) from the microscopic string density of states rho_s (m,H) of mass m in de Sitter space-time. We find for high m, a {\bf new} phase transition at the critical string temperature T_s= (1/2 pi k_B)L c^2/alpha', higher than the flat space (Hagedorn) temperature t_s. (L = c/H, the Hubble constant H acts at the t

Mokhtar Hassaine

We establish a correspondence between a conformally invariant complex scalar field action (with a conformal self-interaction potential) and the action of a phantom scalar field minimally coupled to gravity (with a cosmological constant). In this correspondence, the module of the complex scalar field is used to relate conformally the metrics of both systems w

C. Adam, J. Sanchez-Guillen, A. Wereszczynski

It has been known for some time that for a large class of non-linear field theories in Minkowski space with two-dimensional target space the complex eikonal equation defines integrable submodels with infinitely many conservation laws. These conservation laws are related to the area-preserving diffeomorphisms on target space. Here we demonstrate that for all

I. L Buchbinder, V. A. Krykhtin

We develop the BRST approach to Lagrangian formulation for massive bosonic and massless fermionic higher spin fields on a flat space-time of arbitrary dimension. General procedure of gauge invariant Lagrangian construction describing the dynamics of the fields with any spin is given. No off-shell constraints on the fields (like tracelessness) and the gauge p

Konstantinos Dimopoulos

We investigate a particular type of curvaton mechanism, under which inflation can occur at Hubble scale of order 1 TeV. The curvaton is a pseudo Nambu-Goldstone boson, whose order parameter increases after a phase transition during inflation, triggered by the gradual decrease of the Hubble scale. The mechanism is studied in the context of modular inflation,

A. Flores-Tlalpa, G. Lopez Castro, G. Toledo Sanchez

We consider the bremsstrahlung and model-dependent contributions to the radiative decay $τ^- \to π^-π^0ν_τγ$ in the context of a meson dominance model. We focus on several observables related to this decay, including the branching ratio and the photon and di-pion spectra. Particular attention is paid to the sensitivity of different observables upon the effec

Martin Lavelle, David McMullan

The Lee-Nauenberg theorem is a fundamental quantum mechanical result which provides the standard theoretical response to the problem of collinear and infrared divergences. Its argument, that the divergences due to massless charged particles can be removed by summing over degenerate states, has been successfully applied to systems with final state degeneracie

K. Dimopoulos, G. Lazarides

We study a particular supersymmetric realization of the Peccei-Quinn symmetry which provides a suitable candidate for the curvaton field. The class of models considered also solves the mu problem, while generating the Peccei-Quinn scale dynamically. The curvaton candidate is a pseudo Nambu-Goldstone boson corresponding to an angular degree of freedom orthogo

O. V. Utyuz, G. Wilk, Z. Wlodarczyk

We describe an attempt to numerically model Bose-Einstein correlations (BEC) from "within", i.e., by using them as the most fundamental ingredient of a Monte Carlo event generator (MC) rather than considering them as a kind of (more or less important, depending on the actual situation) "afterburner", which inevitably changes the original phys

Konstantin S. Kuzmin, Vladimir V. Lyubushkin, Vadim A. Naumov

The total charged-current (anti)neutrino-nucleon cross section is usually estimated by the sum of contributions from quasi-elastic scattering (QES), single-pion production through baryon resonances (RES), and deep inelastic scattering (DIS) with an appropriate scratching the phase space of the RES and DIS contributions. However the resulting total cross sect

S. V. Goloskokov

An analysis of light vector meson photoproduction at small $x$ on the basis of the generalized parton distribution (GPD) approach is presented. Our results on the cross section and spin density matrix elements (SDME) are in fair agreement with DESY experiments. The predicted double spin longitudinal $A_{LL}$ asymmetry is not small at HERMES energies.

Peter Skands, Tilman Plehn, David Rainwater

In the production of very heavy final states - high Mandelstam s-hat - extra QCD radiation can play a significant role. By comparing several different parton shower approximations to results obtained with fixed-order perturbation theory, we quantify the degree to which these approaches agree (or disagree), focussing on initial state radiation above pT = 50 G

Hai-Yang Cheng, Kwei-Chou Yang

Weak radiative baryonic B decays $\bar B\to B_1\bar B_2γ$ mediated by the electromagnetic penguin process $b\to sγ$ are re-examined within the framework of the pole model. The meson pole contribution that has been neglected before is taken into account in this work. It is found that the intermediate $K^*$ contribution dominates in the $Σ\bar pγ$ mode and is

Stanislaw Mrowczynski

Due to anisotropic momentum distributions the parton system produced at the early stage of relativistic heavy-ion collisions is unstable with respect to the magnetic plasma modes. The instabilities isotropize the system and thus speed up the process of its equilibration. The whole scenario of the instabilities driven isotropization is reviewed.

Markus Michael Muller

We present kinetic equations that describe the evolution of O(N)-symmetric real scalar quantum fields out of thermal equilibrium in a systematic nonperturbative approximation scheme. This description starts from the 1/N-expansion of the 2PI effective action to next-to-leading order, which includes scattering and memory effects. From this starting point one i

E. -M. Ilgenfritz, W. Kerler, M. Müller-Preussker, A. Sternbeck

In this letter we report on a numerical investigation of the Aoki phase in the case of finite temperature which continues our former study at zero temperature. We have performed simulations with Wilson fermions at $β=4.6$ using lattices with temporal extension $N_τ=4$. In contrast to the zero temperature case, the existence of an Aoki phase can be confirmed

M. D'Elia, A. Di Giacomo, C. Pica

The study of QCD with two light dynamical fermions is of fundamental importance to understand the mechanism of color confinement. We present results of a numerical investigation on the order of the chiral phase transition with $N_f = 2$ by use of a novel strategy in finite size scaling analysis. We compare the critical behaviour of the specific heat, of the

Jakob Lamey, Gustav M. Obermair

In what respect does terrestrial physics reflect the two unique features of the global gravitational field: its infinite range and its equivalence to spacetime curvature? We quote the evidence that true irreversibility, i.e the growth of the Boltzmann entropy of any finite system, is the consequence of the global state of the gravitation dominated and expand

G. De Risi

We present a simple model in which a brane with anisotropic metric is embedded in an AdS bulk. We discuss the localization of the massless mode and the amplification of both the massless and the massive modes on the branes, paying particular attention to the normalization of the perturbed action and to the evaluation of the effective coupling constant that c

I. Radinschi

The Keski-Vakkuri, Kraus and Wilczek (KKW) analysis is used to compute the temperature and entropy in the dyadosphere of a charged black hole solution. For our purpose we choose the dyadosphere region of the Reissner-Nordstrom black hole solution. Our results show that the expressions of the temperature and entropy in the dyadosphere of this charged black ho

Naresh Dadhich

As a homage to A K Raychaudhuri, I derive in a straightforward way his famous equation and also indicate the problems he was last engaged in.

W. Kang, S. Ulukus

The capacity region of the multiple access channel with arbitrarily correlated sources remains an open problem. Cover, El Gamal and Salehi gave an achievable region in the form of single-letter entropy and mutual information expressions, without a single-letter converse. Cover, El Gamal and Salehi also gave a converse in terms of some n-letter mutual informa

Ignatios Souvatzis

SR (synchronizing resources) is a PASCAL - style language enhanced with constructs for concurrent programming developed at the University of Arizona in the late 1980s. MPD (presented in Gregory Andrews' book about Foundations of Multithreaded, Parallel, and Distributed Programming) is its successor, providing the same language primitives with a different

Yann Semet, Sylvain Gelly, Marc Schoenauer, Michèle Sebag

Pertaining to Agent-based Computational Economics (ACE), this work presents two models for the rise and downfall of speculative bubbles through an exchange price fixing based on double auction mechanisms. The first model is based on a finite time horizon context, where the expected dividends decrease along time. The second model follows the {\em greater fool

Roberto Amadio

We revisit the SL synchronous programming model introduced by Boussinot and De Simone (IEEE, Trans. on Soft. Eng., 1996). We discuss an alternative design of the model including thread spawning and recursive definitions and we explore some basic properties of the revised model: determinism, reactivity, CPS translation to a tail recursive form, computational

Carlos Kavka, Patricia Roggero, Marc Schoenauer

A fuzzy controller is usually designed by formulating the knowledge of a human expert into a set of linguistic variables and fuzzy rules. Among the most successful methods to automate the fuzzy controllers development process are evolutionary algorithms. In this work, we propose the Recurrent Fuzzy Voronoi (RFV) model, a representation for recurrent fuzzy sy

Francesco Capasso

In this paper is presented an heuristic that, in polynomial time and space in the input dimension, determines if a circuit describes a tautology or a contradiction. If the circuit is neither a tautology nor a contradiction, then the heuristic finds an assignment to the circuit inputs such that the circuit is satisfied.

K. A. Al-Hassanieh, V. V. Dobrovitski, E. Dagotto, B. N. Harmon

In this work, we consider decoherence of a central spin by a spin bath. In order to study the non-perturbative decoherence regimes, we develop an efficient mean-field-based method for modeling the spin-bath decoherence, based on the P-representation of the central spin density matrix. The method can be applied to longitudinal and transversal relaxation at di

L. -M. Duan

We propose a detection method for ultracold atoms which allows reconstruction of the full one-particle and two-particle correlation functions from the measurements. The method is based on Fourier sampling of the time-of-flight images through two consecutive impulsive Raman pulses. For applications of this method, we discuss a few examples, including detectio

M. V. Erementchouk, L. I. Deych, A. A. Lisyansky

The dispersion properties of exciton polaritons in multiple-quantum-well based resonant photonic crystals are studied. In the case of structures with an elementary cell possessing a mirror symmetry with respect to its center, a powerful analytical method for deriving and analyzing dispersion laws of the respective normal modes is developed. The method is use

Madalina Furis, Jennifer Hollingsworth, Victor I. Klimov, Scott A. Crooker

In an effort to elucidate the spin (rather than charge) degrees of freedom in colloidal semiconductor nanocrystal quantum dots, we report on a series of static and time-resolved photoluminescence measurements of colloidal CdSe quantum dots in ultra-high magnetic fields up to 45 Tesla. At low temperatures (1.5 K - 40 K), the steady-state photoluminescence (PL

Julián Candia, Ezequiel V. Albano

The irreversible growth of a binary mixture under far-from-equilibrium conditions is studied in three-dimensional confined geometries of size $L_x \times L_y \times L_z$, where $L_z \gg L_x = L_y$ is the growing direction. A competing situation where two opposite surfaces prefer different species of the mixture is analyzed. Due to this antisymmetric conditio

Julián Candia, Ezequiel V. Albano

The Magnetic Eden Model (MEM) with ferromagnetic interactions between nearest-neighbor spins is studied in $(d+1)-$dimensional rectangular geometries for $d = 1,2$. In the MEM, magnetic clusters are grown by adding spins at the boundaries of the clusters. The orientation of the added spins depends on both the energetic interaction with already deposited spin

Eytan Grosfeld, Ady Stern

The Moore-Read Pfaffian $ν=5/2$ quantum Hall state is a p-wave super-conductor of composite fermions. Small deviations from $ν=5/2$ result in the formation of an array of vortices within this super-conductor, each supporting a Majorana zero mode near its core. Here we consider how tunneling between these cores is reflected in the electronic response to an el

A. S. Gittings, D. J. Durian

All prior applications of Diffusing-Wave Spectroscopy (DWS) to aqueous foams rely upon the assumption that the electric field of the detected light is a Gaussian random variable and that, hence, the Siegert relation applies. Here we test this crucial assumption by simultaneous measurement of both second and third-order temporal intensity correlations. We fin

Y. -W. Tan, J. Zhu, H. L. Stormer, L. N. Pfeiffer

We determine the spin susceptibility $χ$ in the weak interaction regime of a tunable, high quality, two-dimensional electron system in a GaAs/AlGaAs heterostructure. The band structure effects, modifying mass and g-factor, are carefully taken into accounts since they become appreciable for the large electron densities of the weak interaction regime. When pro

Jurgen F. Stilck, Minos A. Neta, Wellington G. Dantas

Using a transfer matrix technique, we calculate the entropy of polydisperse chains placed on a one-dimensional lattice, as a function of the density of internal and endpoint monomers. The polydispersivity is determined considering different activities for the two types of monomers, as is usual for equailibrium polymerization and living polymers. If the mean

José B. Caballero, Antonio M. Puertas

The equilibrium phase diagram of a 1:1 symmetrical mixture composed of oppositely charged colloids is calculated using Monte Carlo simulations. We model the system by the DLVO effective interaction potential. The phase diagram is similar to that of its atomic analog (the ionic fluid), where a liquid-gas first order transition emerges in the low $T-ρ$ regions

F. P. Mena, J. F. DiTusa, D. van der Marel, G. Aeppli

The narrow gap semiconductor FeSi owes its strong paramagnetism to electron-correlation effects. Partial Co substitution for Fe produces a spin-polarized doped semiconductor. The spin-polarization causes suppression of the metallic reflectivity and increased scattering of charge carriers, in contrast to what happens in other magnetic semiconductors, where ma

E. Y. Tsymbal, K. D. Belashchenko, J. P. Velev, S. S. Jaswal

In the past few years the phenomenon of spin dependent tunneling (SDT) in magnetic tunnel junctions (MTJs) has aroused enormous interest and has developed into a vigorous field of research. The large tunneling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible application in random access memories and magnetic field sensors. Thi

M. Wagenknecht, H. Eitel, T. Nachtrab, J. B. Philipp

Using low-temperature scanning laser microscopy we directly image electric transport in a magnetoresistive element, a manganite thin film intersected by a grain boundary (GB). Imaging at variable temperature allows reconstruction and comparison of the local resistance vs temperature for both, the manganite film and the GB. Imaging at low temperature also sho

E. Bascones, T. M. Rice

Recent inelastic neutron scattering measurements found that the spin susceptibility of detwinned and highly ordered ortho-II YBa_2Cu_3O_{6.5} exhibits, in both the normal and superconducting states, one-dimensional incommensurate modulations at low energies which were interpreted as a signature of dynamic stripes. We propose an alternative model based on qua

Franz Wegner

First we give an introduction to the method of diagonalizing or block-diagonalizing continuously a Hamiltonian and explain how this procedure can be used to analyze the two-dimensional Hubbard model. Then we give a short survey on applications of this flow equation on other models. Finally we outline, how symmetry breaking can be introduced by means of a sym

Matteo Beccaria, Massimo Campostrini, Alessandra Feo

We apply Density Matrix Renormalization Group methods to study the phase diagram of the quantum ANNNI model in the region of low frustration where the ferromagnetic coupling is larger than the next-nearest-neighbor antiferromagnetic one. By Finite Size Scaling on lattices with up to 80 sites we locate precisely the transition line from the ferromagnetic phas

D. Bazeia, J. Menezes, R. Menezes

We review investigations on defects in systems described by real scalar fields in (D,1) space-time dimensions. We first work in one spatial dimension, with models described by one and two real scalar fields, and in higher dimensions. We show that when the potential assumes specific form, there are models which support stable global defects for D arbitrary. W

Vyacheslavs Kashcheyevs, Amnon Aharony, Ora Entin-Wohlman

The equations-of-motion (EOM) hierarchy satisfied by the Green functions of a quantum dot embedded in an external mesoscopic network is considered within a high-order decoupling approximation scheme. Exact analytic solutions of the resulting coupled integral equations are presented in several limits. In particular, it is found that at the particle-hole symme

Xiang Wu, Bing-Hong Wang, Tao Zhou, Wen-Xu Wang

In this letter, we consider the effect of clustering coefficient on the synchronizability of coupled oscillators located on scale-free networks. The analytic result for the value of clustering coefficient aiming at a highly clustered scale-free network model, the Holme-Kim is obtained, and the relationship between network synchronizability and clustering coe

Gerardo Aquino, Luca Leuzzi, Theo M. Nieuwenhuizen

The Kovacs protocol, based on the temperature shift experiment originally conceived by A.J. Kovacs for glassy polymers, is implemented in an exactly solvable dynamical model. This model is characterized by interacting fast and slow modes represented respectively by spherical spins and harmonic oscillator variables. Due to this fundamental property, the model

B. Cleuren, C. Van den Broeck, R. Kawai

We elucidate the connection between various fluctuation theorems by a microcanonical version of the Crooks relation. We derive the microscopically exact expression for the work distribution in an idealized Joule experiment, namely for an object, convex but otherwise of arbitrary shape, moving at constant speed through an ideal gas. Analytic results are compa

Johann Sée, Philippe Dollfus, Sylvie Galdin, Patrice Hesto

The purpose of this article is to present an accurate way, based on a physical description, to simulate Coulomb blockade devices. The method underlying the simulations depends only on fundamental parameters of the system and does not require the use of high level fitting parameters as tunneling conductances contrary to number of current Coulomb blockade simu

D. Reguera, J. M. Rubi, J. M. G. Vilar

Concepts of everyday use like energy, heat, and temperature have acquired a precise meaning after the development of thermodynamics. Thermodynamics provides the basis for understanding how heat and work are related and with the general rules that the macroscopic properties of systems at equilibrium follow. Outside equilibrium and away from macroscopic regime

Amir Aghamohammadi, Mohammad Khorrami

The most general one dimensional reaction-diffusion model with nearest-neighbor interactions solvable through the empty interval method, and without any restriction on the particle-generation from two adjacent empty sites is studied. It is shown that turning on the reactions which generate particles from two adjacent empty sites, results in a gap in the spec

Einat Klein, Noam Gross, Michael Rosenbluh, Wolfgang Kinzel

The dynamics of two mutually coupled chaotic diode lasers are investigated experimentally and numerically. By adding self feedback to each laser, stable isochronal synchronization is established. This stability, which can be achieved for symmetric operation, is essential for constructing an optical public-channel cryptographic system. The experimental result

M. G. Vasin, V. I. Lad'yanov

Liquid is represented as complicated system of disclinations according to defect description of liquids and glasses. The expressions for the linear disclination field of an arbitrary form and energy of inter-disclination interaction are derived in the framework of gauge theory of defects. It allows us to describe liquid as a disordered system of topological

Subhashish Banerjee, Abhishek Dhar

The equation for the Wigner function describing the reduced dynamics of a single harmonic oscillator, coupled to an oscillator bath, was obtained by Karrlein and Grabert [Phys. Rev. E, vol. 55, 153 (1997)]. It was shown that for some special correlated initial conditions the equation reduces, in the classical limit, to the corresponding classical Fokker-Plan

Adilet Imambekov, Eugene Demler

We consider one dimensional interacting bose-fermi mixture with equal masses of bosons and fermions, and with equal and repulsive interactions between bose-fermi and bose-bose particles. Such a system can be realized in current experiments with ultracold bose-fermi mixtures.We apply the Bethe-ansatz technique to find the exact ground state energy at zero tem

Elsa Prada, Fernando Sols

We propose the use of normal and Andreev resonances in normal-superconducting structures to generate divergent beams of nonlocally entangled electrons. Resonant levels are tuned to selectively transmit electrons with specific values of the perpendicular energy, thus fixing the magnitude of the exit angle. When the normal metal is a ballistic two-dimensional

Sz. Csonka, A. Halbritter, G. Mihaly

In this paper an experimental study of the interaction of hydrogen molecules with gold nanowires is presented. Our results show, that chains of Au atoms can also be pulled in hydrogen environment, however in this case the conductance of the chain is strongly reduced compared to the perfect transmission of pure Au chains. The comparison of our experiments wit

Taotao Fang, Christopher McKee, Claude Canizares, Mark Wolfire

Recent Chandra and XMM observations of distant quasars have shown strong local (z~0) X-ray absorption lines from highly ionized gas, primarily He-like oxygen. The nature of these X-ray absorbers, i.e., whether they are part of the hot gas associated with the Milky Way or part of the intragroup medium in the Local Group, remains a puzzle due to the uncertaint

Shirley Ho, Neta Bahcall, Paul Bode

We investigate the dependence of ellipticities of clusters of galaxies on cosmological parameters using large-scale cosmological simulations. We determine cluster ellipticities out to redshift unity for LCDM models with different mean densities $Ω_m$ and amplitudes of mass fluctuation $σ_{8,0}$. The mean ellipticity increases monotonically with redshift for

Stefan Harfst, Christian Theis, Gerhard Hensler

We present a new particle code for modelling the evolution of galaxies. The code is based on a multi-phase description for the interstellar medium (ISM). We included star formation (SF), stellar feedback by massive stars and planetary nebulae, phase transitions and interactions between gas clouds and ambient diffuse gas, namely condensation, evaporation, dra

Ravi K. Sheth, Andrew J. Connolly, Ramin Skibba

The two-point correlation function has been the standard statistic for quantifying how galaxies are clustered. The statistic uses the positions of galaxies, but not their properties. Clustering as a function of galaxy property, be it type, luminosity, color, etc., is usually studied by analysing a subset of the full population, the galaxies in the subset cho

Ravi K. Sheth

Marked statistics allow sensitive tests of how galaxy properties correlate with environment, as well as of how correlations between galaxy properties are affected by environment. A halo-model description of marked correlations is developed, which incorporates the effects which arise from the facts that typical galaxy marks (e.g., luminosity, color, star form

Lilia P. Bassino, Tom Richtler, Boris Dirsch

We present a photometric study of the globular cluster systems of the Fornax cluster galaxies NGC 1374, NGC 1379, and NGC 1387. The data consists of images from the wide-field MOSAIC Imager of the CTIO 4-m telescope, obtained with Washington C and Kron-Cousins R filters. The images cover a field of 36 x 36 arcmin, corresponding to 200 x 200 kpc at the Fornax

A. Mignone, S. Massaglia, G. Bodo

This paper presents an application of the recent relativistic HLLC approximate Riemann solver by Mignone & Bodo to magnetized flows with vanishing normal component of the magnetic field. The numerical scheme is validated in two dimensions by investigating the propagation of axisymmetric jets with toroidal magnetic fields. The selected jet models show that th

V. Belokurov, N. W. Evans, M. J. Irwin, P. C. Hewett

We report the discovery of tidal tails around the high-latitude Galactic globular cluster NGC 5466 in Sloan Digital Sky Survey (SDSS) data. Neural networks are used to reconstruct the probability distribution of cluster stars in u,g,r,i and z space. The tails are clearly visible, once extra-galactic contaminants and field stars have been eliminated. They ext

S. A. Levshakov, M. Centurion, P. Molaro, S. D'Odorico

Verification of theoretical predictions of an oscillating behavior of the fine-structure constant alpha with cosmic time requires high precision Delta alpha/alpha measurements at individual redshifts, while in earlier studies the mean Delta alpha/alpha values averaged over wide redshift intervals were usually reported. This requirement can be met via the sin

Gloria Sala, Jochen Greiner, Frank Haberl, Eckhard Kendziorra

We present results of a sequence of XMM-Newton observations of the two microquasars GRO J1655-40 and GRS 1915+105. The observations were preformed using the EPIC-pn camera in the Burst mode. The observations of GRO J1655-40 in a bright state have made possible a substantial improvement in the calibration of the Burst mode, with determination of the rate depe

S. Justham, S. Rappaport, Ph. Podsiadlowski

We examine the proposal that the subset of neutron-star and black-hole X-ray binaries that form with Ap or Bp star companions will experience systemic angular-momentum losses due to magnetic braking, not otherwise operative with intermediate-mass companion stars. We suggest that for donor stars possessing the anomalously high magnetic fields associated with

D. E. Harris, C. C. Cheung, J. A. Biretta, W. Sparks

The X-ray intensity of knot HST-1, 0.85" from the nucleus of the radio galaxy M87, has increased by more than a factor of 50 during the last 5 years. The optical increase is similar and our more limited radio data indicate a commensurate activity. We give the primary results of our Chandra X-ray Observatory monitoring program and consider some of the imp

D. Clowe, P. Schneider, A. Aragon-Salamanca, M. Bremer

We present weak lensing mass reconstructions for the 20 high-redshift clusters i n the ESO Distant Cluster Survey. The weak lensing analysis was performed on deep, 3-color optical images taken with VLT/FORS2, using a composite galaxy catalog with separate shape estimators measured in each passband. We find that the EDisCS sample is composed primarily of clus

Ewald Puchwein, Matthias Bartelmann, Klaus Dolag, Massimo Meneghetti

Previous studies of strong gravitational lensing by galaxy clusters neglected the potential impact of the intracluster gas. Here, we compare simulations of strong cluster lensing including gas physics at increasing levels of complexity, i.e. with adiabatic, cooling, star-forming, feedback-receiving, and thermally conducting gas, and with different implementa

S. Hofmann, O. Winkler

We calculate the power spectrum of vacuum fluctuations of a generic scalar field in a quantum cosmological setting that is manifestly singularity-free. The power spectrum is given in terms of the usual scale invariant spectrum plus scale dependent corrections. These are induced by well-defined quantum fluctuations of de Sitter spacetime, resulting in a modif

HongSheng Zhao, LanLan Tian

Dark Matter (DM) theories and mass-tracing-light theories like MOND are by construction nearly degenerate on galactic scales, but not when it comes to the predicted shapes of Roche Lobes of a two-body system (e.g., a globular cluster orbiting a host galaxy). We show that the flattening of the Roche lobe is sensitive to the function mu(g) in modification of t

Richard Dipper, Stephen Doty

We extend the family of classical Schur algebras in type A, which determine the polynomial representation theory of general linear groups over an infinite field, to a larger family, the rational Schur algebras, which determine the rational representation theory of general linear groups over an infinite field. This makes it possible to study the rational repr

Z. Kuznetsova, M. Rojas, F. Toppan

We present an algorithmic classification of the irreps of the $N$-extended one-dimensional supersymmetry algebra linearly realized on a finite number of fields. Our work is based on the 1-to-1 \cite{pt} correspondence between Weyl-type Clifford algebras (whose irreps are fully classified) and classes of irreps of the $N$-extended 1D supersymmetry. The comple

M. Skeide

After discussing some basic facts about generalized module maps, we use the representation theory of the algebra of adjointable operators on a Hilbert B-module E to show that the quotient of the group of generalized unitaries on E and its normal subgroup of unitaries on E is a subgroup of the group of automorphisms of the range ideal of E in B. We determine

Philip C. Argyres, Mohammad Edalati

Using the generalized Konishi anomaly (GKA) equations, we derive the effective superpotential of four-dimensional N=1 supersymmetric SU(n) gauge theory with n+2 fundamental flavors. We find, however, that the GKA equations are only integrable in the Seiberg dual description of the theory, but not in the direct description of the theory. The failure of integr

I. Ferreras, A. Pasquali, R. R. de Carvalho, I. G. de la Rosa

(Abridged) Environmental differences in the stellar populations of early-type galaxies are explored using principal component analysis (PCA), focusing on differences between elliptical galaxies in Hickson Compact Groups (HCGs) and in the field. The method is model-independent and relies on variations between the observed spectra. The projections (PC1,PC2) re

Kun Yang, Subir Sachdev

We describe the quantum phase transition of a Fermi gas occurring when the quasiparticle excitation energy has a minimum in momentum space which crosses zero on a sphere of radius k_0 \neq 0. The quasiparticles have a universal interaction which controls the physical properties in vicinity of the quantum critical point. We discuss applications to fermionic s

STAR Collaboration

We have searched for strangelets in a triggered sample of 61 million central (top 4%) Au+Au collisions at $\sNN = 200 $GeV near beam rapidities at the STAR detector. We have sensitivity to metastable strangelets with lifetimes of order $\geq 0.1 ns$, in contrast to limits over ten times longer in AGS studies and longer still at the SPS. Upper limits of a few

Hideaki Kudoh, Atsushi Taruya, Takashi Hiramatsu, Yoshiaki Himemoto

Future missions of gravitational-wave astronomy will be operated by space-based interferometers, covering very wide range of frequency. Search for stochastic gravitational-wave backgrounds (GWBs) is one of the main targets for such missions, and we here discuss the prospects for direct measurement of isotropic and anisotropic components of (primordial) GWBs

Cristiano Germani, Christos G. Tsagas

We investigate the gravitational implosion of magnetized matter by studying the inhomogeneous collapse of a weakly magnetized Tolman-Bondi spacetime. The role of the field is analyzed by looking at the convergence of neighboring particle worldlines. In particular, we identify the magnetically related stresses in the Raychaudhuri equation and use the Tolman-B

Yakov Eliashberg, Sang Seon Kim, Leonid Polterovich

Gromov's famous non-squeezing theorem (1985) states that the standard symplectic ball cannot be symplectically squeezed into any cylinder of smaller radius. Does there exist an analogue of this result in contact geometry? Our main finding is that the answer depends on the sizes of the domains in question: We establish contact non-squeezing on large scale

S. Bekhechi, B. W. Southern, A. Peles, D. Mouhanna

Critical scaling and universality in the short-time dynamics for antiferromagnetic models on a three-dimensional stacked triangular lattice are investigated using Monte Carlo simulation. We have determined the critical point by searching for the best power law for the order parameter as a function of time and measured the critical exponents. Our results indi

Paul H. Frampton

In order that nonsupersymmetric quiver gauge theories can satisfy naturalness requirements to all orders of perturbation theory, one expects a global symmetry similar to, but different from, supersymmetry. Consistent with the generalized no-go theorem published by Haag {\it et al} in 1975, we suggest a generalization of supersymmetry to a misaligned supersym

Ruvim Lipyanski

We consider homogeneous varieties of linear algebras over an associative-commutative ring K with 1, i.e., the varieties in which free algebras are graded. Let F be a free algebra of some variety A of linear algebras over K freely generated by a finite set X, EndF be the semigroup of endomorphisms of F, and AutEndF be the group of automorphisms of the semigro

Pedro Marronetti

Full relativistic simulations in three dimensions invariably develop runaway modes that grow exponentially and are accompanied by violations of the Hamiltonian and momentum constraints. Recently, we introduced a numerical method (Hamiltonian relaxation) that greatly reduces the Hamiltonian constraint violation and helps improve the quality of the numerical m

Yu. L. Dokshitzer, G. Marchesini, G. P. Salam

This remark is part of an ongoing project to simplify the structure of the multi-loop anomalous dimensions for parton distributions and fragmentation functions. It answers the call for a "structural explanation" of a "very suggestive" relation found by Moch, Vermaseren and Vogt in the context of the x->1 behaviour of three-loop DIS anomalous

Ernesto P. Danieli, Gonzalo A. Alvarez, Patricia R. Levstein, Horacio M. Pastawski

We introduce a microscopic Hamiltonian model of a two level system with many-body interactions with an environment whose excitation dynamics is fully solved within the Keldysh formalism. If a particle starts in one of the states of the isolated system, the return probability oscillates with the Rabi frequency $ω_{0}$. For weak interactions with the environme

Joris Vankerschaver, Frans Cantrijn

We present a geometric framework for discrete classical field theories, where fields are modeled as "morphisms" defined on a discrete grid in the base space, and take values in a Lie groupoid. We describe the basic geometric setup and derive the field equations from a variational principle. We also show that the solutions of these equations are multi

Kunihito Ioka, Kenji Toma, Ryo Yamazaki, Takashi Nakamura

Most X-ray afterglows of gamma-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase t^{-1/2} in the first few hours. This is not predicted by the standard afterglow model and needs an explanation. We discuss that the shallow decay requires an unreasonably high gamma-ray efficiency, >75-90%, within current models, which is difficult to

Tathagata Basak

In this article we study a second example of the phenomenon studied in "Complex Lorentzian Leech lattice and bimonster".(Arxiv. math.GR/0508228). The results and methods of proof are similar. We find 14 roots in the automorphism group of the the quaternionic Lorentzian Leech lattice L that form the Coxeter diagram D given by the incidence graph of pr

Anastasios Psinas

We investigate aspects of quantum cosmology in relation to string cosmology systems that are described in terms of the Dirac-Born-Infeld action. Using the Silverstein-Tong model, we analyze the Wheeler-DeWitt equation for the rolling scalar and gravity as well for $R\times{S^3}$ universe, by obtaining the wave functions for all dynamical degrees of freedom o

Michael Baake, Daniel Lenz, Robert V. Moody

It is shown how regular model sets can be characterized in terms of regularity properties of their associated dynamical systems. The proof proceeds in two steps. First, we characterize regular model sets in terms of a certain map $\beta$ and then relate the properties of $\beta$ to ones of the underlying dynamical system. As a by-product, we can show that re

Takao Aoki, Go Takahashi, Akira Furusawa

We report generation of squeezed vacuum in sideband modes of continuous-wave light at 946 nm using a periodically poled KTiOPO_4 crystal in an optical parametric oscillator. At the pump power of 250 mW, we observe the squeezing level of -5.6+/-0.1 dB and the anti-squeezing level of +12.7+/-0.1 dB. The pump power dependence of the observed squeezing/anti-sque