October 1997 arXiv papers — page 19

Heiko Feldmann, Robert Shrock, Shan-Ho Tsai

We show an exact equivalence of the free energy of the $q$-state Potts antiferromagnet on a lattice $Λ$ for the full temperature interval $0 \le T \le \infty$ and the free energy of the $q$-state Potts model on the dual lattice for a semi-infinite interval of complex temperatures (CT). This implies the existence of two quite different types of CT singulariti

E. Balkovsky, G. Falkovich

We describe two complementary formalisms designed for the description of probability density function (PDF) of the gradients of turbulent fields. The first approach, we call it adiabatic, describes PDF at the values much less than dispersion. The second, instanton, approach gives the tails of PDF at the values of the gradient much larger than dispersion. Tog

Hector Giacomini, Sebastien Neukirch

In recent papers we have introduced a method for the study of limit cycles of the Lienard system: dot{x}=y-F(x), dot{y}=-x, where F(x) is an odd polynomial. The method gives a sequence of polynomials R_n(x), whose roots are related to the number and location of the limit cycles, and a sequence of algebraic approximations to the bifurcation set of the system.

Awadhesh Prasad, Vishal Mehra, Ramakrishna Ramaswamy

Strange nonchaotic attractors (SNA) arise in quasiperiodically driven systems in the neighborhood of a saddle node bifurcation whereby a strange attractor is replaced by a periodic (torus) attractor. This transition is accompanied by Type-I intermittency. The largest nontrivial Lyapunov exponent $Λ$ is a good order-parameter for this route from chaos to SNA

Bruce A. Bassett

We demonstrate the parametric amplification of the stochastic gravitational wave background during inflationary reheating and during axion/moduli oscillations. This amplification enhances the detectability of the string/inflationary gravity wave signal, leaving a finger-print on the spectrum which might be found with future gravitational wave detectors.

Brian Chaboyer, P. Demarque, D. B. Guenther

A grid of stellar evolution models for Procyon A has been calculated. These models include the best physics available to us (including the latest opacities and equation of state) and are based on the revised astrometric mass of Girard et al. (1996). The long standing discrepancy between the evolutionary mass and the astrometric mass is now resolved, a result

P. S. Ray, R. S. Foster, E. B. Waltman, M. Tavani

LSI +61 303 is an exotic binary system consisting of a ~10 Msun B star and a compact object which is probably a neutron star. The system is associated with the interesting radio source GT0236+610 that exhibits bright radio outbursts with a period of 26.5 days. We report the results of continuous daily radio interferometric observations of GT0236+610 at 2.25

Patricia A. Whitelock

Our understanding of large amplitude pulsating stars and their status in stellar evolution is briefly reviewed. The paper then describes the near-infrared light curves of various asymptotic giant branch stars, concentrating on possible evidence for changing mass-loss rates. The stars discussed include oxygen- and carbon-rich Miras, OH/IR stars, thick-shelled

Guenther Walther

There exists a considerable amount of research claiming a puzzling anti-correlation between the neutrino detection rate at the Homestake experiment and indicators of solar activity such as the sunspot number, giving rise to explanations involving the hypothesis of a neutrino magnetic moment. It is argued here that the claimed significant anti-correlation is

R. A. Mendez, W. F. van Altena

A new optical reddening model for the Solar neighborhood is presented. The model makes use of the large-scale properties of the dust layer in the Galaxy, and of the observed clumpiness in its distribution, and it is used to compute starcounts in the plane of the Galaxy, which are compared to the observed counts from the Guide Star Catalogue (GSC) for a few r

F. Combes

This symposium has revealed considerable new progress on nuclei of galaxies over the last three years. In this talk, I will try to point out the advances since the last meeting on exactly the same subject held three years ago at Ringberg Castle the Galactic Center", ed. R. Genzel and A. Harris, Kluwer.

Andrew C. Layden

I review the properties of the Galaxy's stellar halo, specifically as traced by horizontal branch stars, but with reference to and in comparison with other stellar tracers. I discuss the halo density profile, the variation in horizontal branch morphology with Galactic position, and the kinematics of halo stars in several regions of the Galaxy. I summariz

Giovanni Vladilo

The effects of the dust on the determination of elemental abundances in damped Ly alpha (DLA) absorbers are investigated. Relations between the observed abundances measured in the gas phase and the overall abundances (gas plus dust) are derived as a function of dust-to-gas ratio, metallicity, element-to-element abundance pattern, average extinction coefficie

G. Vladilo, M. Centurion, R. Falomo, P. Molaro

We present a spectroscopic and imaging study of the z=0.558 MgII absorption system towards the BL Lac PKS 0118-272. At the absorber redshift we detect lines of the low ionization species MgI, MgII, CaII, TiII, MnII, and FeII. The column densities of these species are typical of the interstellar gas in the disk of the Galaxy. By assuming dust-free gas with so

Erik Kuulkers, Rudy Wijnands, Tomaso Belloni, Mariano Mendez

Using the RXTE PCA we discovered deep dips in the X-ray light curves of the black-hole candidates GRO J1655-40 and 4U 1630-47 during outburst. Similar kind of dips for GRO J1655-40 were found in 90s measurements of the RXTE ASM during the same outburst. The duration of the dips in both sources is in the order of minutes. The occurrences of the dips observed

Simon F. Portegies Zwart, Frank Verbunt, Ene Ergma

We study the formation of low-mass X-ray binaries with a black hole as accreting object. The performed semi-analytic analysis reveals that the formation rate of black holes in low-mass X-ray binaries is about two orders of magnitude smaller than that of systems with a neutron star as accretor. This is contradicted by the six observed systems, which are all t

G. Cremonese, H. Boehnhardt, J. Crovisier, A. Fitzsimmons

We report on the discovery and analysis of a striking neutral sodium gas tail associated with comet C/1995 O1 Hale-Bopp. Sodium D-line emission has been observed at heliocentric distance r<1.4 AU in some long-period comets and the presence of neutral sodium in the tailward direction of a few bright comets has been noted, but the extent, and in particular the

F. A. Ringwald, T. Naylor

BZ Cam is the first cataclysmic variable star with an accretion disk wind evident in its optical spectrum. The wind was found by Thorstensen, who discovered intermittent P Cygni profiles occurring simultaneously in He I 5876 Angstroms and H alpha. We have since obtained spectra with 0.4-Angstroms/pixel dispersion and 60-s time resolution. We find a wind much

Oleg Y. Gnedin

Anticipating new spectroscopic studies of quasar companions, we calculate expected emission line spectra for the companion galaxies. Under the assumption of isotropic photoionizing radiation, we predict equivalent widths for Halpha, Hbeta, [O III], [O II], [Ne III], and Mg II lines. We consider 6 quasars, two of which (PKS 2135-14 and PKS 2349-014) have very

P. Ruiz-Lapuente

Supernovae are bright luminous stellar objects observable up to redshifts close to z~1. They are used to probe the geometry of the Universe and its expansion rate by applying different methods. In this article, I review various approaches used to measure the present expansion rate of the Universe, $H_{0}$, and the paths to determine its matter density $Ω_{M}

Masashi Chiba, Yuzuru Yoshii

We present the three-dimensional orbital motions of metal-poor stars in conjunction with their metal abundances, for the purpose of getting insight into the formation process of the Galaxy. Our sample stars, which include metal-deficient red giants and RR Lyrae variables observed by the Hipparcos satellite, are least affected by known systematics, stemmed fr

Savdeep Sethi

We present a matrix model which interpolates between type IIA and type IIB NS five-branes. The matrix description involves a three-dimensional bulk quantum field theory interacting with impurities localized in one spatial direction. We obtain a dual matrix formulation for the exotic six-dimensional theory on coincident type IIB NS five-branes by studying the

Benjamin Grinstein, Detlef R. Nolte

We begin the process of classifying all supersymmetric theories with quantum modified moduli. We determine all theories based on a single SU or Sp gauge group with quantum modified moduli. By flowing among theories we have calculated the precise modifications to the algebraic constraints that determine the moduli at the quantum level. We find a class of theo

Kirill Krasnov

A quantum mechanical description of black hole states proposed recently within non-perturbative quantum gravity is used to study the emission and absorption spectra of quantum black holes. We assume that the probability distribution of states of the quantum black hole is given by the ``area&#39;&#39; canonical ensemble, in which the horizon area is used inst

Aharon Davidson

We examine the possibility that Friedman-Robertson-Walker evolution is governed by an effective (rather then by the actual) energy density. A concrete example is provided by $Λ=0$ Regge-Teitelboim cosmology, where critical cosmology only requires subcritical matter density $(Ω_{m}<1)$, and the age of a flat matter dominated Universe gets enhanced by a factor

T. Yokoo, S. Raymond, A. Zheludev, S. Maslov

Linear-chain nickelates with the composition (Nd_x Y_{1-x})_2 Ba Ni O_5 (x=1, x=0.75, x=0.5, and x=0.25) are studied in a series of neutron scattering experiments. Powder diffraction is used to determine the temperature dependence of the magnetic structure in all four systems. Single-crystal inelastic neutron scattering is employed to investigate the tempera

Kin-Wang Ng, Guo-Chin Liu

We give a full analysis of the auto- and cross-correlations between the Stokes parameters of the cosmic microwave background. In particular, we derive the windowing function for an antenna with Gaussian response in polarization experiment, and construct correlation function estimators corrected for instrumental noise. They are applied to calculate the signal

David A. Kosower

I derive a single factorization formula which summarizes all soft and collinear divergences of a tree-level gauge theory amplitude. The singular factor squared is in a certain sense the generalization of the Catani-Seymour dipole factorization formula.

C. R. Allton

This paper is a review of recent lattice determinations of the light quark masses. It describes the method employed to calculate quark masses in the lattice formulation, and the extrapolations required to reach the physical regime. This review is designed to be accessible to a general audience, not specifically lattice theorists.

Dubravko Klabucar, Dalibor Kekez

Extending our earlier treatments of pi0, eta_c and eta_b, we study the eta-eta&#39; system and its gamma-gamma decays using a model which is a leading version of the consistently coupled Schwinger-Dyson (SD) and Bethe-Salpeter (BS) approach. The electromagnetic interactions are incorporated through a (generalized) impulse approximation consistent with this b

Mark Bowick

In this talk I review some of the recent developments in the field of random surfaces and the Dynamical Triangulation approach to simplicial quantum gravity. In two dimensions I focus on the c=1 barrier and the fractal dimension of two-dimensional quantum gravity coupled to matter with emphasis on the comparison of analytic predictions and numerical simulati

Y. M. Vilk, S. Allen, H. Touchette, S. Moukouri

It is shown that in the two-dimensional attractive Hubbard model, the mean-field phase transition is replaced by a renormalized classical regime of fluctuations where a pseudogap opens up in the single-particle spectral weight. It is argued that this pseudogap and precursors of the ordered state quasiparticles can occur only in strongly anisotropic quasi two

S. M. Bilenky, C. Giunti, W. Grimus

We discuss long-baseline neutrino oscillations in the framework of the two 4-neutrino schemes which can accommodate all existing neutrino oscillation data. Negative results of short-baseline reactor and accelerator experiments allow to obtain rather strong bounds on the long-baseline nu_e->nu_e and nu_mu->nu_e transition probabilities. We consider in detail

V. E. Rochev, P. A. Saponov

A new nonperturbative approach is used to investigate the Gross-Neveu model of four fermion interaction in the space-time dimensions 2, 3 and 4, the number $N$ of inner degrees of freedom being a fixed integer. The spontaneous symmetry breaking is shown to exist in $D=2,3$ and the running coupling constant is calculated. The four dimensional theory seems to

Cristina Manuel

Chiral symmetry is used as the guiding principle to derive hard thermal loop effects in chiral perturbation theory. This is done by using a chiral invariant background field method for the non-linear sigma model and the Wess-Zumino-Witten lagrangian, with and without external vector and axial vector sources. It is then shown that the n-point hard thermal loo

M. Schroeder, W. Kinzel

An artificial neural network can be used to generate a series of numbers. A boolean perceptron generates bit sequences with a periodic structure. The corresponding spectrum of cycle lengths is investigated analytically and numerically; it has similarities with properties of rational numbers.

I. Antoniadis, S. Dimopoulos, G. Dvali

We show that theories in which supersymmetry is broken via Scherk-Schwarz compactification at the weak scale, possess at least one scalar particle with Compton wavelength in the millimetre range, which mediates a force with strength 1/3 of gravity. Such forces are going to be explored in upcoming experiments using micro-electromechanical systems or cantileve

A W Blain, R J Ivison, Ian Smail

The first observations to detect a population of distant galaxies directly in the submillimetre waveband have recently been made using the new Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). The results indicate that a large number of distant galaxies are radiating strongly in this waveband. Here we discuss thei

N. J. Cerf, C. Adami, R. M. Gingrich

We analyze the properties of the conditional amplitude operator, the quantum analog of the conditional probability which has been introduced in [quant-ph/9512022]. The spectrum of the conditional operator characterizing a quantum bipartite system is invariant under local unitary transformations and reflects its inseparability. More specifically, it is shown

B. J. Boyle, I. Georgantopoulos, A. J. Blair, G. C. Stewart

We present additional optical spectroscopic identifications of sources identified in three deep ASCA GIS fields which also form part of a deep ROSAT survey. In total, 26 ASCA sources have been detected down to a 2-10keV flux limit of S = 5e-14 erg/cm/s. LDSS observations have increased the spectroscopic completeness of the survey to between 65 and 85 per cen

Matt Visser, David Hochberg

Wormholes and black holes have traditionally been treated a quite separate objects with relatively little overlap. The possibility of a connection arises in that wormholes, if they exist, might have profound influence on black holes, their event horizons, and their internal structure. After discussing some connections, we embark on an overview of what can ge

Donald Spector

We find examples of duality among quantum theories that are related to arithmetic functions by identifying distinct Hamiltonians that have identical partition functions at suitably related coupling constants or temperatures. We are led to this after first developing the notion of partial supersymmetry-in which some, but not all, of the operators of a theory

Douglas Singleton

A possible resolution to the question of where the nucleon gets some portion of its internal angular momentum, not carried by the valence quarks, is given in terms of the electromagnetic field angular momentum of the nucleon. This field angular momentum is similiar in origin to that of the Thomson dipole (an electric charge and a magnetic monopole), but aris

T. Shigehara, H. Mizoguchi, T. Mishima, Taksu Cheon

We clarify from a general perspective, the condition for the appearance of chaotic energy spectrum in quantum pseudointegrable billiards with a point scatterer inside.

T. Shigehara, H. Mizoguchi, T. Mishima, Taksu Cheon

We discuss spectral properties of the Laplacian with multiple ($N$) point interactions in two-dimensional bounded regions. A mathematically sound formulation for the problem is given within the framework of the self-adjoint extension of a symmetric (Hermitian) operator in functional analysis. The eigenvalues of this system are obtained as the poles of a tran

D. Cocolicchio, M. Viggiano

In this paper, the WKB approximation to the scattering problem is developed without the divergences which usually appear at the classical turning points. A detailed procedure of complexification is shown to generate results identical to the usual WKB prescription but without the cumbersome connection formulas.

P. Zanardi, M. Rasetti

We argue that several claims of paper Phys. Rev. Lett 79, 1953 (1997), by Lu-Ming Duan and Guang-Can Guo, are questionable. In particular we stress that the environmental noise considered by the authors belongs to a very special class

Fusun Akman

We produce a master identity {m}{m}=0 for homotopy Gerstenhaber algebras, as defined by Getzler and Jones and utilized by Kimura, Voronov, and Zuckerman in the context of topological conformal field theories. To this end, we introduce the notion of a &#34;partitioned multilinear map&#34; and explain the mechanics of composing such maps. In addition, many new

Doug Bullock, Charles Frohman, Joanna Kania-Bartoszyńska

We construct lattice gauge field theory based on a quantum group on a lattice of dimension 1. Innovations include a coalgebra structure on the connections, and an investigation of connections that are not distinguishable by observables. We prove that when the quantum group is a deformation of a connected algebraic group (over the complex numbers), then the a

Jonathan Fine

This note defines a flag vector for $i$-graphs. The construction applies to any finite combinatorial object that can be shelled. Two possible connections to quantum topology are mentioned. Further details appear in the author&#39;s &#34;On quantum topology, hypergraphs and flag vectors&#34;, (preprint q-alg/9708001).

Anatoly N. Kochubei

We construct an irreducible representation of the canonical commutation relations by operators on a certain Banach space over a local field of characteristic p. The Carlitz polynomials forming the basis of the space are shown to be the counterparts of the Hermite functions for this situation. The analogues of coherent states are related to the Carlitz expone

E. L. Lomon

Exotic hadrons of a few GeV/c^2 mass, exhibiting a spectrum determined by the perturbative interaction of a non-minimal number of valence quarks, have long been predicted as signals of the underlying QCD structure. Models that include the confinement region, in addition to the region of asymptotic freedom, predict exotic masses 0.2--0.8 GeV higher than the o

L. J. Abu-Raddad, J. Piekarewicz, A. J. Sarty, M. Benmerrouche

We study the nuclear (or A) dependence of the coherent eta photoproduction reaction in a relativistic impulse approximation approach. We use a standard relativistic parameterization of the elementary amplitude, based on a set of four Lorentz- and gauge-invariant amplitudes, to calculate the coherent production cross section from He-4, C-12, and Ca-40. In con

Takashi Nakatsukasa, Niels R. Walet

A model Hamiltonian describing a two-level system with a crossing plus a pairing force is investigated using technique of large-amplitude collective motion. The collective path, which is determined by the decoupling conditions, is found to be almost identical to the one in the Born-Oppenheimer approximation for the case of a strong pairing force. For the wea

Jan Ryckebusch, Dimitri Debruyne, Wim Van Nespen

The polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei are studied. It is pointed out that they open good perspectives to study the dynamics of dinucleons in the medium in detail. The ($γ,pp$) and ($γ,pn$) angular cross sections, photon asymmetries and outgoing nucleon polarizations are calculated for the target nuclei $^

D. S. Kosov, A. I. Vdovin, J. Wambach

Based on the formalism of thermo-field dynamics a new approach for studying collective excitations in hot finite Fermi systems is presented. Two approximations going beyond the thermal RPA namely renormalized thermal RPA and thermal second RPA are formulated.

S. A. Rakityansky, S. A. Sofianos

An exact method for direct calculation of the Jost functions and Jost solutions for non-central potentials which couple partial waves of different angular momenta is presented. A combination of the variable-constant method with the complex coordinate rotation is used to replace the matrix Schrödinger equation by an equivalent system of linear first--order di

Nathan Seiberg

We consider the compactification of M theory on a light-like circle as a limit of a compactification on a small spatial circle boosted by a large amount. Assuming that the compactification on a small spatial circle is weakly coupled type IIA theory, we derive Susskind&#39;s conjecture that M theory compactified on a light-like circle is given by the finite $

Adrian R. Lugo

A set of generalized superalgebras containing arbitrary tensor p-form operators is considered in dimensions $D=2n+1$ for $n=1,4 mod 4$ and the general conditions for its existence expressed in the form of generalized Jacobi identities is established. These are then solved in a univoque way and some lowest dimensional cases $ D= 3, 9, 11 $ of possible interes

Martin Cederwall, Anders Westerberg

We propose a method for constructing super-brane actions where every background tensor potential corresponds to a world-volume field strength. The procedure provides a natural coupling to the background and automatically displays the SL(2;Z) symmetry of the IIB string theory. The Dirichlet 3-brane is used as a test ground for these ideas. A polynomial action

Sunil Mukhi

I review some recent developments in our understanding of the dynamics of Z_2 orientifolds of type IIA and IIB strings and M-theory. Interesting physical phenomena that occur in each spacetime dimension from 10 to 1 are summarized, along with some relationships to nonperturbative effects and to M- and F-theory. The conceptual aspects that are highlighted are

J. Kijowski, G. Rudolph, M. Rudolph

The functional integral of the massless Schwinger model in $(1+1)$ dimensions is reduced to an integral in terms of local gauge invariant quantities. It turns out that this approach leads to a natural bosonisation scheme, yielding, in particular the famous `bosonisation rule&#39;&#39; and giving some deeper insight into the nature of the bosonisation phenome

Fermilab E791 Collaboration, E. M. Aitala

We present a measurement of the form-factor ratios r_V=V(0)/A_1(0) and r_2=A_2(0)/A_1(0) for the decay D^+ -> \overline K^{*0} e^+ ν_e. The measurement is based on a signal of approximately 3000 $D^+ -> \overline K^{*0} e^+ ν_e, \overline K^{*0} -> K^-π^+$ decays reconstructed in data from charm hadroproduction experiment E791 at Fermilab. The results are r_

A. A. Pankov, N. Paver

By means of a model-independent analysis, we discuss the constraints on anomalous trilinear gauge-boson couplings that can be obtained from the study of electron-positron annihilation into $W$ pairs at LC with \sqrt{s}=0.5 TeV and 1 TeV. We consider the general CP conserving anomalous effective Lagrangian, as well as some specific models with reduced number

Eugene Golowich, Joachim Kambor

We perform a calculation of the isospin and hypercharge axialvector current propagators to two loops in SU(3)xSU(3) chiral perturbation theory. A large number of order p^6 divergent counterterms are fixed, and complete two-loop renormalized expressions for the pion and eta masses and decay constants are given. The calculated isospin and hypercharge axialvect

Z. Kunszt

I discuss hard diffractive scattering in the framework of perturbative QCD and Regge-parametrization.

Z. Kunszt

This talk is a short overview of the physics potential of the LHC with emphasis on Higgs search and SUSY search. First I review why LHC with the ATLAS and CMS detectors is expected to give a decisive test of the electroweak symmetry breaking mechanism of the Standard Model. Then I consider the Higgs sector of the Standard Model (SM). Finally the search for s

C. W. Kim, J. D. Kim, J. Song

We have studied the position dependence of neutrino energy on the Kusenko-Segrè mechanism as an explanation of the proper motion of pulsars. The mechanism is also examined in three-generation mixing of neutrinos and in a non-adiabatic case. The position dependence of neutrino energy requires the higher value of magnetic field such as $B\sim 3\times 10^{15}$

D. de Florian, R. Sassot

We analyse recent data on the production of forward neutrons in deep inelastic scattering at HERA in the framework of a perturbative QCD description for semi-inclusive processes, which includes fracture functions.

Francois Gelis

We calculate within the Hard Thermal Loop expansion the production rate of soft photons and lepton pairs by a hot quark-gluon plasma at thermal equilibrium, up to the 2-loop order. Strong collinear divergences appear to mix the orders of the perturbative expansion so that the 2-loop order is in fact dominant compared to the 1-loop order. More precisely, angu

V. A. Maisheev

Propagation of gamma-beam in the anisotropic medium is considered. The simpliest example of such a medium of the general type is a combination of the two linearly polarized monochromatic laser waves with different frequencies (dichromatic wave). The optical properties of this combination are described with the use of the permittivity tensor. The refractive i

Andreas S. Kronfeld

The charm quark&#39;s mass is determined from Monte Carlo calculations of the $\bar{c}c$ spectrum. The main sources of uncertainty are perturbation theory (for conversion to $\MSbar$), the continuum-limit extrapolation, Monte Carlo statistics, and the effects of quenching. The (preliminary) result for the $\MSbar$ mass is $\bar{m}_{ch}(m_{ch})=1.33\pm 0.08$

APE collaboration, A. Bartoloni, S. Cabasino, N. Cabibbo

We report on the progress and status of the APEmille project: a SIMD parallel computer with a peak performance in the TeraFlops range which is now in an advanced development phase. We discuss the hardware and software architecture, and present some performance estimates for Lattice Gauge Theory (LGT) applications.

Hiroko Ichie, Atsunori Tanaka, Hideo Suganuma

We study the role of the monopole for color confinement by using the monopole current system. For the self-energy of the monopole current less than ln$(2d-1)$, long and complicated monopole world-lines appear and the Wilson loop obeys the area law, and therefore the monopole current system almost reproduces essential features of confinement properties in the

J. E. Hetrick, Ph. de Forcrand

We present a new method of gauge fixing to standard lattice Landau gauge, Max Re Tr $\sum_{μ,x}U_{μ,x}$, in which the link configuration is recursively smeared; these smeared links are then gauge fixed by standard extremization. The resulting gauge transformation is simultaneously applied to the original links. Following this preconditioning, the links are g

C. Alexandrou, A. Borici, A. Feo, Ph. de Forcrand

We present results, for heavy to moderate quark masses, of a study of thermodynamic properties of 1-flavour QCD, using the multiboson algorithm. Finite-size scaling behaviour is studied on lattices of size $8^3\times 4$, $12^3\times 4$ and $16^3\times 4$. It is shown that, for heavy quarks, the peak of the Polyakov loop susceptibility grows linearly with the

Ph. de Forcrand, M. Garcia Perez, J. E. Hetrick, I. -O. Stamatescu

We study topological properties of SU(3) gauge theory using improved cooling. In the absence of fermions, we measure a topological susceptibility of $(182(8) MeV)^4$ and an instanton size $\sim 0.6$ fm. In the presence of light staggered fermions and across the chiral transition, the susceptibility drops in a manner consistent with the quenched case, and the

Carlo Rovelli

The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its convent

A. Ashtekar, J. Baez, A. Corichi, K. Krasnov

A `black hole sector&#39; of non-perturbative canonical quantum gravity is introduced. The quantum black hole degrees of freedom are shown to be described by a Chern-Simons field theory on the horizon. It is shown that the entropy of a large non-rotating black hole is proportional to its horizon area. The constant of proportionality depends upon the Immirzi

Mirta S. Iriondo, Enzo O. Leguizamón, Oscar A. Reula

We show that the 3+1 vacuum Einstein field equations in Ashtekar&#39;s variables constitutes a first order symmetric hyperbolic system for arbitrary but fixed lapse and shift fields, by suitable adding to the system terms proportional to the constraint equations.

Mirta S. Iriondo, Enzo O. Leguizamón, Oscar A. Reula

By suitably re-scaling the conformal Einstein&#39;s equations we are able to apply recent results in the theory of PDE, and prove that they possess slow solutions in a future neighborhood of an initial surface reaching ${\cal I}^+$. The structure of the equations obtained allows to split (up to any given order) the initial data into those generating slow sol

A. Banerjee, A. Beesham, S. Chatterjee, A. A. Sen

The well known monopole solution of Barriola and Vilenkin (BV) resulting from the breaking of a global SO(3) symmetry is extended in general relativity along with a zero mass scalar field and also in Brans-Dicke(BD) theory of gravity.In the case of BD theory, the behaviour of spacetime and other variables such as BD scalar field and the monopole energy densi

L. Leherte, J. Glasgow, K. Baxter, E. Steeg

A fundamental goal of research in molecular biology is to understand protein structure. Protein crystallography is currently the most successful method for determining the three-dimensional (3D) conformation of a protein, yet it remains labor intensive and relies on an expert&#39;s ability to derive and evaluate a protein scene model. In this paper, the prob

Ronen Segev, Eshel Ben-Jacob

In order to form the intricate network of synaptic connections in the brain, the growth cones migrate through the embryonic environment to their targets using chemical communication. As a first step to study self-wiring, 2D model systems of neurons have been used. We present a simple model to reproduce the salient features of the 2D systems. The model incorp

A. Kraemer, E. Diaz-Herrera

A density-functional approach is used to calculate the inhomogeneous vortex density distribution in the flux liquid phase at the planar surface of a layered superconductor, where the external magnetic field is perpendicular to the superconducting layers and parallel to the surface. The interactions with image vortices are treated within a mean field approxim

A. D. Dinsmore, D. T. Wong, Philip Nelson, A. G. Yodh

We explore the interplay of membrane curvature and nonspecific binding due to excluded-volume effects among colloidal particles inside lipid bilayer vesicles. We trapped submicron spheres of two different sizes inside a pear-shaped, multilamellar vesicle and found the larger spheres to be pinned to the vesicle&#39;s surface and pushed in the direction of inc

D. Ullmo, K. Richter, H. U. Baranger, F. von Oppen

We study interaction effects on the orbital magnetism of diffusive mesoscopic quantum systems. By combining many-body perturbation theory with semiclassical techniques, we show that the interaction contribution to the ensemble averaged quantum thermodynamic potential can be reduced to an essentially classical operator. We compute the magnetic response of dis

Juergen Horbach, Walter Kob, Kurt Binder

Using molecular dynamics computer simulations we investigate the dynamics of supercooled silica in the frequency range 0.5-20~THz and the wave-vector range 0.13-1.1Å^{-1}. We find that for small wave-vectors the dispersion relations are in very good agreement with the ones found in experiments and that the frequency at which the boson-peak is observed shows

M. Batsch, L. Schweitzer, B. Kramer

Using the method of energy-level statistics, the localization properties of electrons moving in two dimensions in the presence of a perpendicular random magnetic field and additional random disorder potentials are investigated. For this model, extended states have recently been proposed to exist in the middle of the band. In contrast, from our calculations o

Kelin Wang, Jinlong Yang, Tongzhong Li, Gan Qin

The polariton system is studied by a concise approach using a simple model. A new ground state with negative energy is obtained and found to exhibit the symmetry breaking.

P. J. Klar, D. Wolverson, D. E. Ashenford, B. Lunn

Large-area high density patterns of quantum dots with a diameter of 200 nm have been prepared from a series of four Zn_{0.93}Mn_{0.07}Te/ZnTe multiple quantum well structures of different well width (4 nm, 6 nm, 8 nm and 10 nm) by electron beam lithography followed by Ar+ ion beam etching. Below-bandgap photomodulated reflectivity spectra of the quantum dot

E. Tutis, H. Niksic, S. Barisic

In this lecture we present some interesting issues that arise when the dynamics of the charge carriers in the CuO$_2$ planes of the high temperature superconductors is considered. Based on the qualitative picture of doping, set by experiments and some previous calculations, we consider the strength of various inter and intra-cell charge transfer susceptibili

J. X. Zhong, U. Grimm, R. A. Roemer, M. Schreiber

We study the statistical properties of energy spectra of two-dimensional quasiperiodic tight-binding models. We demonstrate that the nearest-neighbor level spacing distributions of these non-random systems are well described by random matrix theory. Properly taking into account the symmetries of models defined on various finite approximants of quasiperiodic

Roberto Iengo, Claudio A. Scrucca

We study the dissipative thermodynamics of vortex lines in layered superconductors within a simple string model in the dilute limit of negligible vortex interactions and compute the specific heat $C_v$ in presence of arbitrary dissipation. The interplay of dissipation, inertia and elasticity is shown to control the qualitative thermodynamical behavior and th

Tomas Lofwander, Goran Johansson, Magnus Hurd, Goran Wendin

We study voltage-biased superconducting planar d-wave junctions for arbitrary transmission and arbitrary orientation of the order parameters of the superconductors. For a certain orientation of the superconductors the odd ac components disappear, resulting in a doubling of the Josephson frequency. We study the sensitivity of this disappearance to orientation

Joonhyun Yeo, M. A. Moore

A thin film superconductor shaped into a spherical shell at whose center lies the end of long thin solenoid in which there is an integer flux $NΦ_0$ has been previously extensively studied numerically as a model of a two-dimensional superconductor. The emergent flux from the solenoid produces a radial B-field at the superconducting shell and $N$ vortices in

I. Ichinose, T. Matsui

We study the t-J model on a ladder by using slave-fermion-CP^1 formalism which is quite useful for study of lightly-doped high-T_c cuprates. By integrating half of spin variables, we obtain a low-energy effective field theory whose spin part is nothing but CP^1 sigma model. We especially focus on dynamics of composite gauge field which determines properties

D. Rainer, J. A. Sauls

Superfluid $^3$He confined in aerogel offers a unique chance to study the effects of a short mean free path on the properties of a well defined superfluid Fermi liquid with anisotropic pairing. Transport coefficients and collective excitations, e.g. longitudinal sound, are expected to react sensitively to a short mean free path and to offer the possibility f

Adrienne L. Fairhall, Victor S. L&#39;vov, Itamar Procaccia

A recent theoretical development in the understanding of the small-scale structure of Navier-Stokes turbulence has been the proposition that the scales $η_n(R)$ that separate inertial from viscous behavior of many-point correlation functions depend on the order $n$ and on the typical separations $R$ of points in the correlation. This is a proposal of fundame

M. Lakshmanan

In this set of lectures, we review briefly some of the recent developments in the study of the chaotic dynamics of nonlinear oscillators, particularly of damped and driven type. By taking a representative set of examples such as the Duffing, Bonhoeffer-van der Pol and MLC circuit oscillators, we briefly explain the various bifurcations and chaos phenomena as