October 2002 arXiv papers — page 12

Ralph L. Cohen, John D. S. Jones

Let $M$ be a closed, oriented manifold of dimension $d$. Let $LM$ be the space of smooth loops in $M$. Chas and Sullivan recently defined a product on the homology $H_*(LM)$ of degree $-d$. They then investigated other structure that this product induces, including a Batalin -Vilkovisky structure, and a Lie algebra structure on the $S^1$ equivariant homology

Tosiaki Kori

We shall give an axiomatic construction of Wess-Zumino-Witten actions valued in (G=SU(N)), (N\geq 3). It is realized as a functor ({WZ}) from the category of conformally flat four-dimensional manifolds to the category of line bundles with connection that satisfies, besides the axioms of a topological field theory, the axioms which abstract Wess-Zumino-Witten

Jean Nuyts, Tai Tsun Wu

For semisimple groups, possibly multiplied by U(1)'s, the number of Yang-Mills gauge fields is equal to the number of generators of the group. In this paper, it is shown that, for non-semisimple groups, the number of Yang-Mills fields can be larger. These additional Yang-Mills fields are not irrelevant because they appear in the gauge transformations of

S. Mignemi

We investigate a model of two-dimensional gravity with arbitrary scalar potential obtained by gauging a deformation of de Sitter or more general algebras, which accounts for the existence of an invariant energy scale. We obtain explicit solutions of the field equations and discuss their properties.

G. Bonelli

After a brief review on Matrix String Theory on flat backgrounds, we formulate matrix string models on different pp-wave backgrounds. This will be done both in the case of constant and variable RR background flux for certain exact string geometries. We exhibit the non--perturbative representation of string interaction and show how the eigenvalue tunneling dr

A. Bossard, N. Mohammedi

We study the impact of non-Abelian T-duality transformations on a string based cosmological model. The implementation of the pre-big-bang scenario is investigated. We found a region of the dual phase where such a picture is possible.

A. A. Andrianov, D. Espriu

We assume that QCD can be effectively described with string-like variables. The hadronic string is built over the chirally non-invariant QCD vacuum by means of the boundary interaction with background chiral fields associated with pions. By making this interaction compatible with the conformal symmetry of the string and with the unitarity constraint on chira

Changrim Ahn, Chanju Kim, Chaiho Rim, M. Stanishkov

In this paper we consider a strong-weak coupling duality of the N=2 super-Liouville field theory (SLFT). Without the self-duality found in other Liouville theories, the N=2 SLFT, we claim, is associated with a `dual' action by a transformation $b\to 1/b$ where $b$ is the coupling constant. To justify our conjecture, we compute the reflection amplitudes (

James D. Bjorken

We consider the properties of an ensemble of universes as function of size, where size is defined in terms of the asymptotic value of the Hubble constant (or, equivalently, the value of the cosmological constant). We assume that standard model parameters depend upon size in a manner that we have previously suggested, and provide additional motivation for tha

Gregory Langmead

We construct a mathematical framework for twisted N=2 supersymmetric topological quantum field theory on a 4-manifold. Supersymmetry in flat space is defined and the twist homomorphism is constructed, giving us a supermanifold that is the total space of an odd vector bundle over the even 4-manifold. A special category of connections on this space is defined

Helder Chavez, Luis Masperi

Violation of chiral symmetry together with change of mass sign allows a linear correction in inverse power of new physics scale to the anomalous magnetic moment of muon. In this light we analyse alternative models showing in particular that grand unification, supersymmetry and muon substructure may explain the discrepancy between the experimental value of th

Kenneth Lane, Stephen Mrenna

We discuss the phenomenology of the lightest SU(3)_C singlet and non-singlet technihadrons in the Straw Man Model of low-scale technicolor (TCSM). The technihadrons are assumed to be those arising in topcolor--assisted technicolor models in which topcolor is broken by technifermion condensates. We improve upon the description of the color--singlet sector pre

L. P. Csernai, M. I. Gorenstein, L. L. Jenkovszky, I. Lovas

Possible hadronization of supercooled QGP, created in heavy ion collisions at RHIC and SPS, is discussed within a Bjorken hydrodynamic model. Such a hadronization is expected to be a very fast shock-like process, what, if hadronization coincides or shortly followed by freeze out, could explain a part of the HBT puzzle, i.e. the flash-like particle emission (

Marco Cavaglia

In models with large extra dimensions particle collisions with center-of-mass energy larger than the fundamental gravitational scale can generate non-perturbative gravitational objects such as black holes and branes. The formation and the subsequent decay of these super-Planckian objects would be detectable in particle colliders and high energy cosmic ray de

Stefan Gieseke

After an introduction to event generators we give an overview of developments in the field of joining matrix elements with parton showers. Starting with matrix element corrections, we also discuss implementations that match LO and NLO matrix elements with parton shower results correctly. Finally, the new Monte Carlo program Herwig++ is described. We report o

F. E. Close, A. Donnachie, Yu. S. Kalashnikova

Radiative decays of the $1^3D_1$ orbital excitations of the $ρ$, $ω$ and $ϕ$ to the scalars $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$ are shown to provide a flavour filter, clarifying the extent of glueball mixing in the scalar states. A complementary approach to the latter is provided by the radiative decays of the scalar mesons to the ground-state vectors $

Andrzej J. Buras

We describe the present status of the Unitarity Triangle and we give an outlook for its future determinations. We discuss new sets of fundamental flavour parameters and comment briefly on new physics beyond the Standard Model.

Per Osland

Recent work on analytical solutions to the MSW equations for three neutrino flavours is reviewed, with emphasis on the exponential density. Application to a particular mass matrix, proposed by Lehmann, Newton and Wu, is also discussed. Within this model, the experimental data allow a determination of the three neutrino masses. They are found to be 0.002-0.00

Y. -Y. Keum

We investigate the $B \to K^{*}π$ decays, one of hardly understandable processes among charmless B-meson decays, within the perturbative QCD method. Owing to the dynamically enhanced mechanism in PQCD, we obtain large branching ratios and large direct CP asymmetries, for instance, $Br(B^0 \to K^{*\pm}π^{\mp})=(9.1^{+4.9+0.3}_{-3.9-0.2})\times 10^{-6}$, $Br(B

John Ellis

The search for physics beyond the Standard Model motivates new high-energy accelerators, which will require high luminosities in order to produce interesting new heavy particles. Using the Higgs boson and supersymmetry as examples, we discuss the capabilities of the LHC and $e^+ e^-$ linear colliders in the TeV and multi-TeV energy ranges to discover and stu

Timothy Porter

Some examples from the mathematics of shape are presented that question some of the almost hidden assumptions behind results on limiting behaviour of finitary approximations to space-time. These are presented so as to focus attention on the observational problem of refinement and suggest the necessity for an alternative theory of `fractafolds' against wh

Eugen Radu

We construct new axially symmetric solutions of SU(2) Yang-Mills theory in a four dimensional anti-de Sitter spacetime. Possessing nonvanishing nonabelian charges, these regular configurations have also a nonzero angular momentum. Numerical arguments are also presented for the existence of rotating solutions of Einstein-Yang-Mills equations in an asymptotica

T. Harko, M. K. Mak

We consider the dynamics of a Bianchi type I spacetime in the presence of dilaton and magnetic fields. The general solution of the Einstein-Maxwell dilaton field equations can be obtained in an exact parametric form. Depending on the numerical values of the parameters of the model there are three distinct classes of solutions. The time evolution of the mean

Alexander K. Gouts

The Multiverse is collection of parallel universes. In this article a formal theory and a topos-theoretic models of the multiverse are given. For this the Lawvere-Kock Synthetic Differential Geometry and topos models for smooth infinitesimal analysis are used. Physical properties of multi-variant and many-dimensional parallel universes are discussed. The sou

Jane Hunter

The "event" concept appears repeatedly when developing metadata models for the description and management of multimedia content. During the typical life cycle of multimedia content, events occur at many different levels - from the events which happen during content creation (directing, acting, camera panning and zooming) to the events which happen to

M. G. Vavilov, L. I. Glazman

We investigate the combined effects of magnetic impurities and applied magnetic field on the interference contribution to the conductance of disordered metals. We show that in a metal with weak spin-orbit interaction, the polarization of impurity spins reduces the rate of electron phase relaxation, thus enhancing the weak localization correction to conductiv

R. van Zon, E. G. D. Cohen

Comment on ``Experimental Demonstration of Violations of the Second Law of Thermodynamics for Small Systems and Short Time Scales''

J. R. Anglin

State engineering in nonlinear quantum dynamics sometimes may demand driving the system through a sequence of dynamically unstable intermediate states. This very general scenario is especially relevant to dilute Bose-Einstein condensates, for which ambitious control schemes have been based on the powerful Gross-Pitaevskii mean field theory. Since this theory

Benny Davidovitch, Deniz Ertas, Thomas C. Halsey

We address the surface tension-driven dynamics of porous media in nearly saturated pore-space solutions. We linearize this dynamics in the reaction-limited regime near its fixed points -- surfaces of constant mean curvature (CMC surfaces). We prove that the only stable interface for this dynamics is the plane, and estimate the time scale for a CMC surface to

D. ben-Avraham, B. M. Johnson, C. A. Monaco, P. L. Krapivsky

We investigate two complementary problems related to maintaining the relative positions of N random walks on the line: (i) the leader problem, that is, the probability {\cal L}_N(t) that the leftmost particle remains the leftmost as a function of time and (ii) the laggard problem, the probability {\cal R}_N(t) that the rightmost particle never becomes the le

Marko Sysi-Aho, Anirban Chakraborti, Kimmo Kaski

We present a simple game which mimics the complex dynamics found in most natural and social systems. Intelligent players modify their strategies periodically, depending on their performances. We propose that the agents use hybridized one-point genetic crossover mechanism,inspired by genetic evolution in biology, to modify the strategies and replace the bad s

M. Ausloos, Ph. Bronlet

We have applied the Zipf method to extract the $ζ'$ exponent for seven financial indices (DAX, FTSE; DJIA, NASDAQ, S&P500; Hang-Seng and Nikkei 225), after having translated the signals into a text based on two letters. We follow considerations based on the signal Hurst exponent and the notion of a time dependent Zipf law and exponent in order to impleme

J. C. Egues, P. Recher, D. S. Saraga, V. N. Golovach

We review our recent contributions on shot noise for entangled electrons and spin-polarized currents in novel mesoscopic geometries. We first discuss some of our recent proposals for electron entanglers involving a superconductor coupled to a double dot in the Coulomb blockade regime, a superconductor tunnel-coupled to Luttinger-liquid leads, and a triple-do

Shi-Jian Gu, N. M. R. Peres, You-Quan Li

In this paper we present two new numerical methods for studying thermodynamic quantities of integrable models. As an example of the effectiveness of these two approaches, results from numerical solutions of all sets of Bethe ansatz equations, for small Heisenberg chains, and Monte Carlo simulations in quasi-momentum space, for a relatively larger chains, are

Silvia Tinte, Jorge Iniguez, Karin M. Rabe, David Vanderbilt

The various approximations used in the construction of a first-principles effective Hamiltonian for BaTiO3, and their effects on the calculated transition temperatures, are discussed. An effective Hamiltonian for BaTiO3 is constructed not from first-principles calculations, but from the structural energetics of an atomistic shell model for BaTiO3 of Tinte et

D. S. Dean, R. R. Horgan

A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full non-linear surface terms which are then treated at a one-loop le

Thomas R Weikl

Membrane shape fluctuations induce attractive interactions between rigid inclusions. Previous analytical studies showed that the fluctuation-induced pair interactions are rather small compared to thermal energies, but also that multi-body interactions cannot be neglected. In this article, it is shown numerically that shape fluctuations indeed lead to the dyn

Chris P. Search, Pierre Meystre

We analyze the phase resolution limit of a Mach-Zehnder atom interferometer whose input consists of degenerate quantum gases of either bosons or fermions. For degenerate gases, the number of atoms within one de Broglie wavelength is larger than unity, so that atom-atom interactions and quantum statistics are no longer negligible. We show that for equal atom

Q. A. Wang, A. Bulou, J. Y. Gesland

The pressure effect on the fluoride scheelite laser host $LiYF_4$ is studied at room temperature up to 26 GPa by Raman scattering and up to 40 GPa by $P^{3+}$ fluorescence of doped sample. The Raman spectra exhibit three singularities at the vicinity of 6 GPa, 10-12 GPa and 16-17 GPa. The samples pressurized to 21 GPa or higher do not recover the original ph

L. Buisson, L. Bellon, S. Ciliberto

The fluctuation-dissipation relation (FDR) is measured on the dielectric properties of a gel (Laponite) and of a polymer glass (polycarbonate). For the gel it is found that during the transition from a fluid-like to a solid-like state the fluctuation dissipation theorem is strongly violated. The amplitude and the persistence time of this violation are decrea

Alain Billoire, Barbara Coluzzi

We study the Sherrington--Kirkpatrick model, both above and below the De Almeida Thouless line, by using a modified version of the Parallel Tempering algorithm in which the system is allowed to move between different values of the magnetic field h. The behavior of the probability distribution of the overlap between two replicas at different values of the mag

S. Schneider, A. Kasper, Ch. vom Hagen, M. Bartenstein

A Bose-Einstein condensate is created in a simple and robust miniature Ioffe-Pritchard trap, the so-called Z trap. This trap follows from the mere combination of a Z-shaped current carrying wire and a homogeneous bias field. The experimental procedure allows condensation of typically 3x10^5 Rb-87 atoms in the |F=2, m_F=2> state close to any mirroring surface

A. Kemper, A. Gendiar, T. Nishino, A. Schadschneider

We develop a new variant of the recently introduced stochastic transfer-matrix DMRG which we call stochastic light-cone corner-transfer-matrix DMRG (LCTMRG). It is a numerical method to compute dynamic properties of one-dimensional stochastic processes. As suggested by its name, the LCTMRG is a modification of the corner-transfer-matrix DMRG (CTMRG), adjuste

Sang Wook Kim

We investigate the Pauli blocking factor in quantum pumps using Floquet formalism. Even though the time dependent potentials in quantum pumping can not only cause inelastic scatterings but also break the micro-reversibility, i.e. $T^+(E',E) \neq T^-(E,E')$, the Pauli blocking factor is unnecessary when the scattering process through the scatterer is

G. Gomila, I. R. Cantalapiedra, L. Reggiani

We carry out a self-consistent analytical theory of unipolar current and noise properties of metal-semiconductor-metal structures made of highly resistive semiconductors in the presence of an applied bias of arbitrary strength. By including the effects of the diffusion current we succeed to study the whole range of carrier injection conditions going from low

Shinji Nonoyama, George Kirczenow

We identify the physics behind the results of recent measurements [W. Kang et al., Nature 403, 59 (2000)] of electron transfer between the edges of two two-dimensional electron systems (2DES). We find that a consistent explanation of all of the observed phenomena is possible if the barrier between the 2DES is surrounded by a strong potential well that suppor

J. Enkovaara, A. Ayuela, J. Jalkanen, L. Nordstrom

We report here non-collinear magnetic configurations in the Heusler alloys Ni2MnGa and Ni2MnAl which are interesting in the context of the magnetic shape memory effect. The total energies for different spin spirals are calculated and the ground state magnetic structures are identified. The calculated dispersion curves are used to estimate the Curie temperatu

Andrew K. Jonscher, Agnieszka Jurlewicz, Karina Weron

Unlike the classical exponential relaxation law, the widely prevailing universal law with its fractional power-law dependence of susceptibility on frequency cannot be explained in the framework of any intuitively simple physical concept. The resulting constancy of the ratio of the imaginary to the real parts of the complex susceptibility, known as the ``ener

B. S. Sorensen, J. sadowski, S. E. Andresen, P. E. Lindelof

We present the magnetotransport properties of very thin (5 to 15 nm) single (Ga,Mn)As layers grown by low temperature molecular beam epitaxy. A lower (Ga,Mn)As thickness limit of 5 nm for the ferromagnetic phase and the dependence of the Curie temperature on (Ga,Mn)As thickness are determined from electrical transport measurements. The Curie temperature is d

T. Schneider

To provide an understanding of the universal properties emerging from the empirical correlations and phase diagrams of cuprate superconductors, we invoke the scaling theory of finite temperature and quantum critical phenomena. The universal features are traced back to the existence of quantum critical lines, representing the end lines of the finite temperatu

G. De Smedt, C. Godreche, J. M. Luck

We consider a ferromagnetic Ising chain evolving under Kawasaki dynamics at zero temperature. We investigate the statistics of the metastable configurations in which the system gets blocked (statistics of energy, spin correlations, distribution of domain sizes). A systematic comparison is made with analytical predictions for the ensemble of all blocked confi

Yoshihiro Nishiyama

It has been considered that the effective bending rigidity of fluid membranes should be reduced by thermal undulations. However, recent thorough investigation by Pinnow and Helfrich revealed significance of measure factors for the partition sum. Accepting the local curvature as a statistical measure, they found that fluid membranes are stiffened macroscopica

Eric Smith, J. Doyne Farmer, Laszlo Gillemot, Supriya Krishnamurthy

Most modern financial markets use a continuous double auction mechanism to store and match orders and facilitate trading. In this paper we develop a microscopic dynamical statistical model for the continuous double auction under the assumption of IID random order flow, and analyze it using simulation, dimensional analysis, and theoretical tools based on mean

Sergei V. Kalinin, Dawn A. Bonnell, Marcus Freitag, A. T. Johnson

Electronic transport in semiconducting single-wall carbon nanotubes is studied by combined scanning gate microscopy and scanning impedance microscopy (SIM). Depending on the probe potential, SIM can be performed in both invasive and non-invasive mode. High-resolution imaging of the defects is achieved when the probe acts as a local gate and simultaneously an

Hideo Hasegawa

A semi-analytical dynamical mean-field approximation (DMA) has been developed for large but finite $N$-unit active rotator (AR) networks subject to individual white noises. Assuming weak noises and the Gaussian distribution of state variables, we have derived equations of motions for moments of local and global variables up to the {\it infinite} order. In DM

S. I. Campbell, F. A. Akeroyd, C. M. Moreton-Smith

Open GENIE is the successor to the widely used and high successful GENIE program that is used as the principal front-end neutron data analysis tool at the ISIS spallation neutron source. In this paper, the background and motivation for the Open GENIE project are briefly reviewed, as is the progress to date. Some of the ideas and concepts making Open GENIE un

S. P. Cottrell, D. Flannery, G. Porter, A. D. Hillier

Although originally designed by and for the use of the Neutron and X-ray communities, the flexibility of the NeXus data format makes it equally suitable for storing data gathered from MuSR experiments. Furthermore, its use should open up the possibility of sharing software beyond the immediate muon community; giving access to the many tools that are already

Tobias Unruh

At the new neutron source FRM--II in Garching, Germany, the TACO control system, originally developed at the ESRF in Grenoble, France is used for instrument control purposes. TACO provides an object oriented, distributed control system including a clearly defined API. In order to equip TACO with a general user front end, a network based instrument control sy

G. Oshanin, O. Benichou, S. F. Burlatsky, M. Moreau

In this presentation we overview some recent results on biased tracer diffusion in lattice gases. We consider both models in which the gas particles density is explicitly conserved and situations in which the lattice gas particles undergo continuous exchanges with a reservoir, which case is appropriate, e.g., to adsorbed monolayers in contact with the vapor

A. Cano, A. P. Levanyuk, S. A. Minyukov

We show that the strain-induced attraction between Abrikosov vortices has a non-core contribution overlooked up until now. This contribution is an example of the universal mechanism of soliton attraction in solids revealed in [Phys. Rev. B {\bf 66}, 14111 (2002)]. The resulting interaction energy is larger than that due to the vortex cores at least by a fact

Dean Lee

We present a new approach to the problem of alternating signs for fermionic many body Monte Carlo simulations. We demonstrate that the exchange of identical fermions is typically short-ranged even when the underlying physics is dominated by long distance correlations. We show that the exchange process has a maximum characteristic range of sqrt[2*(1-f)*beta*h

Yoshifusa Ita, Toshihiko Tanabé, Noriyuki Matsunaga, Yasushi Nakajima

The first results of our ongoing near-infrared (NIR) survey of the variable red giants in the Large Magellanic Cloud, using the Infrared Survey Facility (IRSF) and the SIRIUS infrared camera, are presented. Many very red stars were detected and found that most of them are variables. In the observed colour-magnitude diagram ($J-K, K$) and the stellar $K$ magn

F. D. Seward, P. O. Slane, R. K. Smith, M. Sun

A Chandra X-ray observation has detected an unresolved source at the center of the supernova remnant Kes 79. The best single-model fit to the source spectrum is a blackbody with an X-ray luminosity Lx (0.3-8.0 keV) = 7 x 10^{33} ergs s^{-1}. There is no evidence for a surrounding pulsar wind nebula. There are no cataloged counterparts at other wavelengths, b

Simon C. O. Glover

Because H2 formation on dust grain surfaces completely dominates gas-phase H2 formation in local molecular clouds, it is often assumed that gas-phase formation is never important. In fact, it is the dominant mechanism in a number of cases. In this paper, I briefly summarize the chemistry of gas-phase H2 formation, and show that it dominates for dust-to-gas r

J. Mikolajewska, E. A. Kolotilov, S. Yu. Shugarov, A. A. Tatarnikova

One of fundamental questions in relation to symbiotic binaries is the process of mass transfer - Roche lobe overflow or stellar wind - and possibility of an accretion disc formation. The presence of secondary minima in the quiescent light curves of YY Her, CI Cyg and BF Cyg apparently due to ellipsoidal changes of the red giant provides here important clues.

J. Mikolajewska, R. J. Ivison, A. Omont

We present and discuss mm/submm observations of quiescent S-type symbiotic systems, and compare them with popular models proposed to account for their radio emission. We find that the M giant mass-loss rates derived from our observations are systematically higher than those reported for single M giants.

J. Mikolajewska, C. Quiroga, E. Brandi, L. G. Garcia

We present an analysis of optical and near infrared spectra of the symbiotic system AE Ara, composed of an M5.5 III giant similar to the Galactic Bulge M giants and a hot luminous companion. In particular, we have determined for the first time spectroscopic orbits based of the radial velocity curves for the red and the hot component from the M-giant absorpti

Joanna Mikolajewska

This paper reviews current knowledge of symbiotic binaries, with special emphasis on their multifrequency observational characteristics, and basic parameters of the symbiotic system components. We start with a brief presentation of variable phenomena found in symbiotic stars. This is followed by a summary of the recent progress in determination of their orbi

Matthias Stute, Max Camenzind, Hans Martin Schmid

MWC 560 (= V694 Mon) is the only known Symbiotic Star system in which the jet axis is practically parallel to the line of sight. Therefore this system is predestinated to study the dynamical evolution and the propagation of stellar jets. Spectroscopic monitoring done by Schmid et al. (2001) showed that the outflow is seen as absorption features in the contin

Eran O. Ofek, Hans-Walter Rix, Dan Maoz, Francisco Prada

The statistics of large-separation gravitational lensing are a powerful tool to probe mass distributions on the scale of galaxy clusters. In this paper we refine the analysis of our survey for large-separation (>5'') lensed FIRST quasars (Ofek et al. 2001) by estimating the magnification bias and the source redshift distribution. Finding no large sep

N. Andersson, G. L. Comer, R. Prix

Mature neutron stars are expected to have several superfluid components. Strong evidence for this is provided by the glitches that have been observed in dozens of pulsars. The underlying idea behind most glitch models is that, as the neutron star crust spins down due to the emission of electromagnetic radiation, the superfluid component lags behind until a c

M. Bejger, D. G. Yakovlev, O. Y. Gnedin

We extend our modeling of cooling of superfluid neutron stars by including the production of muons in the core, in addition to neutrons, protons, and electrons. The results are confronted with observations of middle-aged isolated NSs. Muons have little effect on the hydrostatic structure of NSs, on the slow cooling of low-mass NSs (RX J0822--43 and PSR 1055-

Winfried Zimdahl, Diego Pavón

We show that with the help of a suitable coupling between dark energy and cold dark matter it is possible to reproduce any scaling solution $ρ_{X}\propto ρ_{M}a^ξ$, where $ρ_{X}$ and $ρ_{M}$ are the densities of dark energy and dark matter, respectively. We demonstrate how the case $ξ= 1$ alleviates the coincidence problem. Future observations of supernovae

P. G. Edwards, B. G. Piner

We have combined Very Long Baseline Interferometry (VLBI) data from several programs in order to resolve differences in reported parsec-scale jet speeds for the TeV gamma-ray source Mkn501. Data from the VLBA 2cm survey, and 8 and 15 GHz data from the Radio Reference Frame Image Database, have been combined with data from a 5 GHz VSOP Space VLBI observation

Yuexing Li, Ralf S. Klessen, Mordecai-Mark Mac Low

We study numerically the effect of varying the equation of state (EOS) on the formation of stellar clusters in turbulent molecular clouds. Our results show that the EOS plays an important role in the fragmentation of the clouds, and the determination of the initial mass function (IMF) of the protostellar cores. Fragmentation decreases with increasing adiabat

H. Garcia-Compean, O. Obregon, C. Ramirez, M. Sabido

The possibility of noncommutative topological gravity arising in the same manner as Yang-Mills theory is explored. We use the Seiberg-Witten map to construct such a theory based on a SL(2,C) complex connection, from which the Euler characteristic and the signature invariant are obtained. This gives us a way towards the description of noncommutative gravitati

J. S. Alcaniz, Deepak Jain, Abha Dev

Motivated by recent developments in particle physics and cosmology, there has been growing interest in an unified description of dark matter and dark energy scenarios. In this paper we explore observational constraints from age estimates of high-$z$ objects on cosmological models dominated by an exotic fluid with equation of state $p = -A/ρ^α$ (the so-called

Naohiro Mae, Shinji Iida

We calculate two-point energy level correlation function in weakly disorderd metallic grain with taking account of localization corrections to the universal random matrix result. Using supersymmetric nonlinear sigma model and exactly integrating out spatially homogeneous modes, we derive the expression valid for arbitrary energy differences from quantum to d

A. Bonanno, M. Reuter

A linear cosmological perturbation theory of an almost homogeneous and isotropic perfect fluid Universe with dynamically evolving Newton constant $G$ and cosmological constant $Λ$ is presented. A gauge-invariant formalism is developed by means of the covariant approach, and the acoustic propagation equations governing the evolution of the comoving fractional

Renyue Cen

We show the universe was reionized twice, first at z~15-16 and second at z~6. Such an outcome appears inevitable, when normalizing to two well determined observational measurements, namely, the epoch of the final cosmological reionization at z~6 and the density fluctuations at z~6, which in turn are tight ly constrained by Lyman alpha forest observations at

Yoshitaka Hatta, Takashi Ikeda

The quark number susceptibility near the QCD critical end-point (CEP), the tricritical point (TCP) and the O(4) critical line at finite temperature and quark chemical potential is investigated. Based on the universality argument and numerical model calculations we propose a possibility that the hidden tricritical point strongly affects the critical phenomena

Gavriel Segre

Charles Bennett's measure of physical complexity for classical objects, namely logical-depth, is used in order to prove that a chaotic classical dynamical system is not physical complex. The natural measure of physical complexity for quantum objects, quantum logical-depth, is then introduced in order to prove that a chaotic quantum dynamical system is no

Darren Madgwick, Rachel Somerville, Ofer Lahav, Richard Ellis

We investigate the physical significance of a new spectral parameter, eta. This parameter was defined using a Principal Component Analysis of the 2dF Galaxy Redshift Survey, to retain astrophysical information while minimising the effect of measurement uncertainties. We find that while eta is correlated with morphological type, there is a large scatter in th

G. Kaniadakis

In the present effort we show that $S_κ=-k_B \int d^3p (n^{1+κ}-n^{1-κ})/(2κ)$ is the unique existing entropy obtained by a continuous deformation of the Shannon-Boltzmann entropy $S_0=-k_B \int d^3p n \ln n$ and preserving unaltered its fundamental properties of concavity, additivity and extensivity. Subsequently, we explain the origin of the deformation me

Nima Arkani-Hamed, Howard Georgi, Matthew D. Schwartz

We introduce a technique for restoring general coordinate invariance into theories where it is explicitly broken. This is the analog for gravity of the Callan-Coleman-Wess-Zumino formalism for gauge theories. We use this to elucidate the properties of interacting massless and massive gravitons. For a single graviton with a Planck scale Mpl and a mass mg, we

A. Broncano, M. B. Gavela, E. Jenkins

The effective Lagrangian for the seesaw model is derived including effects due to CP violation. Besides the usual dimension-5 operator responsible for light neutrino masses, a dimension-6 operator is obtained. For three or less heavy neutrino generations, the inclusion of both operators is necessary and sufficient for all independent physical parameters of t

Claudio Castellano, Daniele Vilone, Alessandro Vespignani

We investigate how the topology of small-world networks affects the dynamics of the voter model for opinion formation. We show that, contrary to what occurs on regular topologies with local interactions, the voter model on small-world networks does not display the emergence of complete order in the thermodynamic limit. The system settles in a stationary stat

Federico Corberi, Giuseppe Gonnella, Eugenio Lippiello, Marco Zannetti

The dynamics of a binary system with non conserved order parameter under a plain shear flow with rate $γ$ is solved analytically in the large-N limit. A phase transition is observed at a critical temperature $T_c(γ)$. After a quench from a high temperature equilibrium state to a lower temperature $T$ a non-equilibrium stationary state is entered when $T>T_c(

Miroslav Jezek, Jaromir Fiurasek, Zdenek Hradil

The maximum-likelihood principle unifies inference of quantum states and processes from experimental noisy data. Particularly, a generic quantum process may be estimated simultaneously with unknown quantum probe states provided that measurements on probe and transformed probe states are available. Drawbacks of various approximate treatments are considered.

Jaume Amorós, Vicente Muñoz, Francisco Presas

We study some asymptotic properties of the sequences of symplectic Lefschetz pencils constructed by Donaldson. In particular we prove that the vanishing spheres of these pencils are, for large degree, conjugated under the action of the symplectomorphism group of the fiber. This implies the non-existence of homologically trivial vanishing spheres in these pen

M. C. Bento, O. Bertolami, A. A. Sen

We study the dependence of the location of the Cosmic Microwave Background Radiation (CMBR) peaks on the parameters of the generalized Chaplygin gas model, whose equation of state is given by $p = - A/ρ^α$, where $A$ is a positive constant and $0 < α\le 1$. We find, in particular, that observational data arising from Archeops for the location of the first pe

A. M. Alekseenko, D. N. Arnold

We derive a new first-order formulation for Einstein&#39;s equations which involves fewer unknowns than other first-order formulations that have been proposed. The new formulation is based on the 3+1 decomposition with arbitrary lapse and shift. In the reduction to first order form only 8 particular combinations of the 18 first derivatives of the spatial met

E. Oset, J. R. Pelaez, L. Roca

We improve the calculations of the $η\to π^0 γγ$ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the $a_0(980)$ resonance and fixing the longstanding sign ambiguity on its contribution. This also allows us to calculate the loops with one vector meson exchange, thus removi

Qiuping A. Wang

We introduce the hypothesis of incomplete information into the fractional exclusion statistics in order to apply the latter to some correlated heavy fermion systems. It is shown that the actual inexplicit distribution function of FES may be replaced by an equivalent explicit one of which the form does not change with $α$ value.

Thorsten Leonhardt, Werner Ruehl

In this note we explicitly compute the graviton exchange graph for scalar fields with arbitrary conformal dimension Δin arbitrary spacetime dimension d. This results in an analytical function in Δas well as in d.

M. T. Dova, M. E. Mancenido, A. G. Mariazzi, T. P. McCauley

In the course of its operation, the Volcano Ranch array collected data on the lateral distribution of showers produced by cosmic rays at energies above $10^{17}$ {\rm eV}. From these data very precise measurements of the steepness of the lateral distribution function, characterized by the $η$ parameter, were made. The current availability of sophisticated ha

R. A. Schneider

This short note considers, within the external field approach outlined in hep-ph/0202026, the role of the lowest lying gluon Landau mode in QCD in the high temperature limit. Its influence on a temperature- and field-dependent running coupling constant is examined. The thermal imaginary part of the mode is temperature-independent in our approach and exactly

Sebastian Martin Ruiz, Jonathan Sondow

Using inequalities of Rosser and Schoenfeld, we prove formulas for pi(n) and the n-th prime that involve only the elementary operations +,-,/ on integers, together with the floor function. Pascal Sebah has pointed out that the formula for pi(n) operates in O(n^(3/2)) time. Similar formulas were proven using Bertrand&#39;s Postulate by Stephen Regimbal, An ex

K. Baerwinkel, H. -J. Schmidt, J. Schnack

Large spin systems as given by magnetic macromolecules or two-dimensional spin arrays rule out an exact diagonalization of the Hamiltonian. Nevertheless, it is possible to derive upper and lower bounds of the minimal energies, i.e. the smallest energies for a given total spin S. The energy bounds are derived under additional assumptions on the topology of th

Frank E. Close, Qiang Zhao

We discuss recent claims that $p\bar{p} \to γγ$ may be described by a generalized parton picture. We propose that quark-hadron duality provides a justification for the effective dominance of the &#34;handbag&#34; diagram assumed in recent literature, and that handbag diagrams may dominate phenomena in kinematic regions far more extensive than that might be e