October 1998 arXiv papers — page 2

Umberto Marini Bettolo Marconi

We investigate the time dependent Ginzburg-Landau (TDGL) equation for a non conserved order parameter on an infinitely ramified (deterministic) fractal lattice employing two alternative methods: the auxiliary field approach and a numerical method of integration of the equations of evolution. In the first case the domain size evolves with time as $L(t)\sim t^

Umberto Marini Bettolo Marconi, Pedro Tarazona

We present a new time-dependent Density Functional approach to study the relaxational dynamics of an assembly of interacting particles subject to thermal noise. Starting from the Langevin stochastic equations of motion for the velocities of the particles we are able by means of an approximated closure to derive a self-consistent deterministic equation for th

M. Hummel, C. Pich, F. Schwabl

We investigate antiferromagnetic spin chains, which are coupled by a weak antiferromagnetic exchange interaction on a hexagonal lattice. We particulary study the role of the dipole-dipole interaction within the framework of a Heisenberg model with nearest-neighbor exchange and additional dipolar interaction. We find several commensurate and incommensurate ph

S. V. Kuplevakhsky, A. V. Naduev, S. V. Naydenov

We discuss some of the basic theoretical aspects of current-carrying states in superconducting superlattices with tunnel barriers in the mesoscopic regime, when the superconducting layer thickness is small compared to the BCS coherence length but large compared to the atomic scale. We establish the necessary conditions for the observation of the classical Jo

Pragya Shukla

. We study the evolution of the distribution of eigenvalues of a $N\times N$ matrix subject to a random perturbation drawn from (i) a generalized Gaussian ensemble (ii) a non-Gaussian ensemble with a measure variable under the change of basis. It turns out that, in the case (i), a redefinition of the parameter governing the evolution leads to a Fokker-Planck

K. Schonhammer

The theoretical description of interacting fermions in one spatial dimension is simplified by the fact that the low energy spectrum of noniteracting fermions is identical to the one of a harmonic chain. This fermion-boson transmutation allows to describe interacting fermions as a system of coupled oscillators. Tomonaga's model of interacting nonrelativis

Predrag Cvitanovic, C. P. Dettmann, Ronnie Mainieri, Gabor Vattay

The trace formula for the evolution operator associated with nonlinear stochastic flows with weak additive noise is cast in the path integral formalism. We integrate over the neighborhood of a given saddlepoint exactly by means of a smooth conjugacy, a locally analytic nonlinear change of field variables. The perturbative corrections are transfered to the co

Jean-Pierre Eckmann, Claude-Alain Pillet, Luc Rey-Bellet

We consider a finite chain of non-linear oscillators coupled at its ends to two infinite heat baths which are at different temperatures. Using our earlier results about the existence of a stationary state, we show rigorously that for arbitrary temperature differences and arbitrary couplings, such a system has a unique stationary state. (This extends our earl

Akihiro Ishizawa, Yuji Hattori

Using EDQNM approximation, it is shown that the magnetic stretching term is responsible for turning the small-scale turbulent structures into the large coherent magnetic structures in the 2-D MHD turbulence.

Anup Rej

Within the framework of star formation in starburst galaxies undergoing interactions, connections among the red quasars, the BL Lacs, and the Blazars with the gamma-ray bursts are discussed in the light of the "hypernovae" scenario. It is proposed that the gamma-ray bursts occur primarily in the star formation regions in starburst environments, and a

P. J. E. Peebles, A. Vilenkin

We present an explicit observationally acceptable model for evolution from inflation to the present epoch under the assumption that the entropy and matter of the familiar universe are from gravitational particle production at the end of inflation. This eliminates the problem of finding a satisfactory coupling of the inflaton and matter fields. Since the infl

Bruce A. Wilking, Thomas P. Greene, Michael R. Meyer

We present an analysis of low resolution infrared spectra for 20 brown dwarf candidates in the core of the $ρ$ Ophiuchi molecular cloud. Fifteen of the sources display absorption-line spectra characteristic of late-type stars. By comparing the depths of water vapor absorption bands in our candidate objects with a grid of M dwarf standards, we derive spectral

Gaspard Duchene

Various surveys of low-mass binaries in star forming regions have been performed in recent years. They reached opposite conclusions concerning possible binary excesses in some of these associations. I develop a consistent method to reanalyze all these studies, so that I can compare all data consistently, and understand the previous findings. I also report th

Martin White

I review why we expect the CMB anisotropy to be polarized, what we can learn from studying polarization and the level of the experimental challenge it presents. A discussion of current and future polarization sensitive experiments will focus on the expected sensitivity of PLANCK.

Cosmology, Xray group, :, M. Plionis

Poster Titles: (1) Optical to IRAS galaxy bias factors using the Local Group Dipole (2) The X-ray Luminosity Function of Local Galaxies (3) The ROSAT X-ray Background Dipole (4) The Angular Correlation Function of RASS Extragalactic Sources (5) Galaxy Cluster Shapes

Roberto Capuzzo-Dolcetta, Paolo Miocchi

We present preliminary results on the parallelization of a Tree-Code for evaluating gravitational forces in N-body astrophysical systems. Our HPF/CRAFT implementation on a CRAY T3E machine attained an encouraging speed-up behavior, reaching a value of 75 with 128 processor elements (PEs). The speed-up tests regard the evaluation of the forces among N = 130,3

Alec Boksenberg, Wallace L. W. Sargent, Michael Rauch

An extremely careful separation of the weak metal-line systems relating to the Lyman forest absorbers into individual ``single-phase ionization&#39;&#39; components with accurate parameters has yielded a large sample in the wide redshift range 1.9 < z < 4.4. The systems typically span several hundred km/s and within each the components show a strong coherenc

A. Biviano, A. Mazure, C. Adami, P. Katgert

We summarize several results based on the velocity data-set for cluster galaxies provided by ENACS (the ESO Nearby Abell Cluster Survey). We describe the distribution of velocity dispersions of a complete sample of rich galaxy clusters, and compare it to the distribution of cluster X-ray temperatures, and with predictions of theoretical models. We then addre

P. Katgert, C. Adami, P. de Theije, A. Mazure

In this paper we summarize the main properties of the ENACS (the ESO Nearby Abell Cluster Survey), which was one of the ESO Keyprogrammes carried out in the first half of the 1990&#39;s, and we discuss some recent work on the properties of the galaxies in the rich clusters in the ENACS sample. We stress the importance of the ENACS sample as a local, volume-l

Sheperd Doeleman Colin Lonsdale Shannon Pelkey

We present full resolution (~0.2mas, ~0.1 A.U.) Very Long Baseline Interferometry maps of the v=1, J=1-0 SiO masers in the Orion-KL nebula. The morphology and turbulent nature of the maser emission argues against models in which the masers form in an expanding and rotating protostellar disk. Rather, we find that the symmetry evident in the SiO maser emission

P. J. E. Peebles

We have fossil evidence from the thermal background radiation that our universe expanded from a considerably hotter denser state. We have a well defined and testable description of the expansion, the relativistic Friedmann-Lemaitre model. Its observational successes are impressive but I think hardly enough for a convincing scientific case. The lists of obser

D. J. Buckley, M. C. Dorrington, P. J. Edwards, T. J. L. McComb

A technique for detecting the presence of cloud in the field of view of an atmospheric Cerenkov telescope using a far infra red radiometer is described. Models for the radiative emission from clear and cloudy skies are tested and found to represent the measurements.

L. Lara, L. Feretti, G. Giovannini, S. Baum

We have observed the radio source NGC 3862 (3C264) simultaneously with the EVN and the MERLIN arrays, obtaining detailed images of its radio structure from parsec to sub-kiloparsec scales. 3C264 shows a one-sided jet, with evident variations in its morphological properties with distance. We have analyzed HST optical data of NGC 3862 finding a one-to-one corr

Y. Dabrowski

Recent X-ray spectroscopy made with ASCA have shown broad, skewed iron line emission from Seyfert-1 galaxies. The large extent of the red tail allows probing of the innermost regions of the black hole&#39;s accretion disc. A model of line emission has been developed and very strong evidence for the presence of a rapidly rotating Kerr black hole has been esta

M. G. Witte, G. J. Savonije

We study the linear, but fully non-adiabatic tidal response of a uniformly rotating, somewhat evolved X_c=0.4, 10 Msun main sequence star to the dominant l=2 components of its binary companion&#39;s tidal potential. This is done numerically with a 2D implicit finite difference scheme. We assume the spin vector of the 10 Msun star to be aligned perpendicular

F. van der Hooft, C. Kouveliotou, J. van Paradijs, W. S. Paciesas

We have studied the hard X-ray variability of the soft X-ray transient GRO J0422+32 with BATSE in the 20-100 keV energy band. Our analysis covers 180 days following the first X-ray detection of the source on 1992 August 5, fully covering its primary and secondary X-ray outburst. We computed power density spectra (PDSs) in the 20-50, 50-100, and 20-100 keV en

R. Michael Jarvis, Gordon M. MacAlpine

In the Hubble Deep Field (HDF), twelve candidate sources of high-redshift (z > 3.5) AGN activity have been identified. The color selection criteria were established by passing spectra of selected quasars and Seyfert galaxies (appropriately redshifted and modified for &#34;Lyman forest&#34; absorption), as well as stars, observed normal and starburst galaxies

Philip J. Armitage, C. J. Clarke, C. A. Tout

We present theoretical models for the evolution of T Tauri stars surrounded by circumstellar discs. The models include the effects of pre-main-sequence stellar and time dependent disc evolution, and incorporate the effects of stellar magnetic fields acting on the inner disc. For single stars, consistency with observations in Taurus-Auriga demands that disc d

A. Loinger

We prove that the anomalous form of Schwarzschild metric within the spatial domain bounded by Schwarzschild pseudosingular surface is a mathematical mishap, devoid of any physical meaning. As a special consequence, the portions of geodesics internal to the above domain are not physically interpretable. Accordingly, the theoretical notion of black hole descri

A. Houghton, H. -J. Kwon, J. B. Marston

Bosonization of degenerate fermions yields insight both into Landau Fermi liquids, and into non-Fermi liquids. We begin our review with a pedagogical introduction to bosonization, emphasizing its applicability in spatial dimensions greater than one. After a brief historical overview, we present the essentials of the method. Well known results of Landau theor

Jacek Dziarmaga, Pablo Laguna, Wojciech H. Zurek

We show that, in second-order phase transformations induced by an inhomogeneous quench, the density of topological defects is drastically suppressed as the velocity with which the quench propagates becomes smaller than the speed at which the front of the broken symmetry phase spreads. The velocity of the broken symmetry phase front is approximately given by

Doron Cohen

Both in atomic physics and in mesoscopic physics it is sometimes interesting to consider the energy time-dependence of a parametrically-driven chaotic system. We assume an Hamiltonian ${\cal H}(Q,P;x(t))$ where $x(t)=Vt$. The velocity $V$ is slow in the classical sense but not necessarily in the quantum-mechanical sense. The crossover (in time) from ballisti

S. Ahlig, R. Alkofer

The Bethe-Salpeter equation provides the most widely used technique to extract bound states and resonances in a relativistic Quantum Field Theory. Nevertheless a thorough discussion how to identify its solutions with physical states is still missing. The occurrence of complex eigenvalues of the homogeneous Bethe-Salpeter equation complicates this issue furth

B. Dion, T. Gregoire, D. London, L. Marleau

We examine, as model-independently as possible, the production of bileptons at hadron colliders. When a particular model is necessary or useful, we choose the 3-3-1 model. We consider a variety of processes: q anti-q -> Y^{++} Y^{--}, u anti-d -> Y^{++} Y^{-}, anti-u d -> Y^+ Y^{--}, q anti-q -> Y^{++} e^{-} e^{-}, q anti-q -> phi^{++} phi^{--}, u anti-d ->

Darwin Chang, We-Fu Chang, Ernest Ma

We propose an alternative interpretation of the top events discovered at the Tevatron in 1995. Given that the charge of the $b$ quark jet cannot be measured for the whole sample with certainty, the signal can be due to a quark of charge -4/3 at the reported mass, i.e. 174 GeV, while the top quark is actually heavier, say above 230 GeV. We point out in this p

B. Z. Kopeliovich, B. Povh

Recent results from the H1 experiment [1] have confirmed the existence of a substantial baryon asymmetry of the proton sea at small $x$ with magnitude predicted in hep-ph/9607486. This is a strong support for the idea [3] that baryon number can be transferred by gluons through a large rapidity interval without attenuation. In this paper we calculate the depe

M. Buballa, M. Oertel

Bulk properties of strange quark matter (SQM) are investigated within the SU(3) Nambu-Jona-Lasinio model. In the chiral limit the model behaves very similarly to the MIT bag model which is often used to describe SQM. However, when we introduce realistic current quark masses, the strange quark becomes strongly disfavored, because of its large dynamical mass.

E. Alvarez, P. Meessen

This is the written version of a set of introductory lectures on string theory.

S. Dalley, B. van de Sande

We use the light-front Hamiltonian of transverse lattice gauge theory to compute from first principles the glueball spectrum and light-front wavefunctions in the leading order of the 1/N_c colour expansion. We find 0^{++}, 2^{++}, and 1^{+-} glueballs having masses consistent with N_c=3 data available from Euclidean lattice path integral methods. The wavefun

E. I. Buchbinder, I. L. Buchbinder, S. M. Kuzenko

We compute the one-loop non-holomorphic effective potential for the N=4 SU(n) supersymmetric Yang-Mills theory with the gauge symmetry broken down to the maximal torus. Our approach remains powerful for arbitrary gauge groups and is based on the use of N=2 harmonic superspace formulation for general N=2 Yang-Mills theories along with the superfield backgroun

B. Chen, H. Itoyama, H. Kihara

The nonabelian Berry phase is computed in the T dualized quantum mechanics obtained from the USp(2k) matrix model. Integrating the fermions, we find that each of the spacetime points X_ν^{(i)} is equipped with a pair of su(2) Lie algebra valued pointlike singularities located at a distance m_{(f)} from the orientifold surface. On a four dimensional paraboloi

N. Chandra, M. Kollar, D. Vollhardt

A nearly universal feature of the specific heat curves C(T,U) vs. T for different U of a general class of Hubbard models is observed. That is, the value C_+ of the specific heat curves at their high-temperature crossing point T_+ is almost independent of lattice structure and spatial dimension d, with C_+/k_B \approx 0.34. This surprising feature is explaine

J. M. Roman, J. Soto

We present a continuum model for doped manganites which consist of two species of quantum spin 1/2 fermions interacting with classical spin fields. The phase structure at zero temperature turns out to be considerably rich: antiferromagnetic insulator, antiferromagnetic two band conducting, canted two band conducting, canted one band conducting and ferromagne

F. Gungor

The purpose of this paper is to present a class of particular solutions of a C(2,1) conformally invariant nonlinear Klein-Gordon equation by symmetry reduction. Using the subgroups of similitude group reduced ordinary differential equations of second order and their solutions by a singularity analysis are classified. In particular, it has been shown that whe

M. Conte, E. Di Salvo, A. Penzo, M. Pusterla

We discuss the perspectives of measuring direct CP violation parameters in hyperon decays by measurements with proton and/or antiproton beams, to be carried out at various facilities, and in particular we propose new experiments at the Tevatron and at the LHC.

Bo-Qiang Ma, Jacques Soffer

It is shown that neutrino and antineutrino deep inelastic scattering of unpolarized and polarized $Λ$ and $\barΛ$ productions, can provide a clean separation of unpolarized and polarized fragmentation functions of a quark into a $Λ$, for both light-flavor quarks and antiquarks and also for strange quarks. Combining with $Λ$ and $\barΛ$ productions in polariz

V. Gogohia, H. Toki, T. Sakai, Gy. Kluge

Using the effective potential approach for composite operators we have formulated the quantum model of the QCD vacuum. It is based on the existence and importance of the nonperturbative $q^{-4}$-type dynamical, topologically nontrivial excitations of the gluon field configuration. The QCD vacuum is found stable since the vacuum energy density has no imaginar

Merced Montesinos, Abdel Pérez-Lorenzana

The non quantum relativistic version of the proof of Feynman for the Maxwell equations is discussed in a framework with a minimum number of hypotheses required. From the present point of view it is clear that the classical equations of motion corresponding to the gauge field interactions can be deduced from the minimal coupling rule, and we claim here reside

Vladimir Pestov

It is proved that a discrete group $G$ is amenable if and only if for every unitary representation of $G$ in an infinite-dimensional Hilbert space $\cal H$ the maximal uniform compactification of the unit sphere $\s_{\cal H}$ has a $G$-fixed point, that is, the pair $(\s_{\cal H},G)$ has the concentration property in the sense of Milman. Consequently, the ma

Hsien-Hung Shih, Shih-Chang Lee, Hsiang-nan Li

We develop perturbative QCD factorization theorems for the exclusive semileptonic heavy baryon decay $Λ_b \to pl{\barν}$, in which the relevant hadronic form factor is expressed as the convolution of a hard subamplitude with the $Λ_b$ baryon wave function and the proton wave function. The specific evolution scale for the proton wave function, determined from

M. J. Ablowitz, Y. Ohta, A. D. Trubatch

The scalar nonlinear Schrodinger (NLS) equation and a suitable discretization are well known integrable systems which exhibit the phenomena of ``effective&#39;&#39; chaos. Vector generalizations of both the continuous and discrete system are discussed. Some attention is directed upon the issue of the integrability of a discrete version of the vector NLS equa

Diego A. R. Dalvit, Francisco D. Mazzitelli

We study the creation of photons in a one dimensional oscillating cavity with two perfectly conducting moving walls. By means of a conformal transformation we derive a set of generalized Moore&#39;s equations whose solution contains the whole information of the radiation field within the cavity. For the case of resonant oscillations we solve these equations

Decio Krause, Steven French

Motivated by considerations in the foundations of quantum mechanics and inspired by the literature on vague predicates, we introduce the concept of an opaque predicate. While in the case of vague predicates there is a kind of indeterminacy with respect to the predicate, in the sense that the vagueness concerns whether a well-determined object satisfies it or

L. Vaidman

Since its discovery in 1993, we witness an intensive theoretical and experimental effort centered on teleportation. Very recently it was claimed in the press that ``quantum teleportation has been achieved in the laboratory&#39;&#39; (T. Sudbery, Nature, 390, p. 551). Here, I briefly review this research focusing on the connection to nonlocal measurements, an

Giseppe Curci, Erika D&#39;Ambrosio

Interferometric gravitational wave detectors are devoted to pick up the effect induced on masses by gravitational waves. The variations of the length dividing two mirrors is measured through a laser interferometric technique. The Brownian motion of the masses related to the interferometer room temperature is a limit to the observation of astrophysical signal

Alexander S. Zazerskiy

The unified field is a Maxwell-Lorentz field. Maxwell-Lorentz equations for potentials in standard four-dimensional form are satisfied exactly. This is achieved by involving new fundamental field sources, strict definition of which requires higher dimensionality. Source currents do not &#34;see&#34; each other enough that, in each point of the space in any d

S. A. Bass, H. Weber, C. Ernst, M. Bleicher

We analyze the reaction dynamics of central Pb+Pb collisions at 160 GeV/nucleon. First we estimate the energy density pile-up at mid-rapidity and calculate its excitation function: The energy density is decomposed into hadronic and partonic contributions. A detailed analysis of the collision dynamics in the framework of a microscopic transport model shows th

Gary Prézeau

The renormalized elastic $ππ$ scattering amplitude to one loop is calculated in the chiral limit in the $σ$ model and in a Quantum Hadrodynamic model (QHD-III) with vector mesons. It is argued that QHD-III reduces to the linear $σ$ model in the limit that the vector meson masses become large. The pion decay constant is also calculated to 1-loop in the $σ$ mo

Abdelghani Zeghib

Here, we classify Lie groups acting isometrically on compact Lorentz manifolds, and in particular we describe the geometric structure of compact homogeneous Lorentz manifolds.

Sarah Rees

A group is combable if it can be represented by a language of words satisfying a fellow traveller property; an automatic group has a synchronous combing which is a regular language. This article surveys results for combable groups, in particular in the case where the combing is a formal language.

Ken&#39;ichi Ohshika

One of the basic problems in studying topological structures of deformation spaces for Kleinian groups is to find a criterion to distinguish convergent sequences from divergent sequences. In this paper, we shall give a sufficient condition for sequences of Kleinian groups isomorphic to surface groups to diverge in the deformation spaces.

Nguyen Anh Ky

Some introductory concepts and basic definitions of the Lie superalgebras and their quantum deformations are exposed. Especially the induced representation methods in both cases are described. Based on the Kac representation theory we have succeeded in constructing representations of several higher rank superalgebras. When representations of quantum superalg

Clara S. Chan, David P. Robbins, David S. Yuen

Let n >= 2 be an integer and consider the set T_n of n by n permutation matrices pi for which pi_{ij}=0 for j>=i+2. In this paper we study the convex hull of T_n, which we denote by P_n. P_n is a polytope of dimension binom{n}{2}. Our main purpose is to provide evidence for the following conjecture concerning its volume. Let v_n denote the minimum volume of

E. Karat

We discuss a simple system which has a central charge in its Poincare algebra. We show that this system is exactly solvable after quantization and that the algebra holds without anomalies.

Jan B. Thomassen

A method to perform bosonization of a fermionic theory in (1+1) dimensions in a path integral framework is developed. The method relies exclusively on the path integral property of allowing variable shifts, and does not depend on the explicit form of Greens functions. Two examples, the Schwinger model and the massless Thirring model, are worked out.

I. A. Batalin, K. Bering, P. H. Damgaard

We give a superfield formulation of the path integral on an arbitrary curved phase space, with or without first class constraints. Canonical tranformations and BRST transformations enter in a unified manner. The superpartners of the original phase space variables precisely conspire to produce the correct path integral measure, as Pfaffian ghosts. When extend

C. P. Burgess, L. E. Ibanez, F. Quevedo

We show that if the string scale is identifed with the intermediate scale, $M_s=\sqrt{M_W M_{Planck}} \sim 10^{11}$ GeV, then the notorious hierarchy, $M_W/M_{Planck} \sim 10^{-16}$, can be explained using only $M_c/M_s \sim 0.01 \sim α_{GUT} $ as small input parameters, where $M_c$ is the compactification scale. This is possible for weakly-coupled Type-I op

Haim Goldberg, T. J. Weiler

A new strong-interaction has been postulated for neutrinos above ~10^{19} eV to explain the production of highest-energy cosmic ray events. We derive a dispersion relation relating the hypothesized high-energy cross-section to the lower-energy neutrino-nucleon elastic amplitude. Remarkably, we find that the real forward amplitude becomes anomalous seven orde

V. Gimenez

For the first time, we compute non-perturbatively, i.e. without lattice perturbation theory, the renormalization constants of two-fermion operators in the quenched approximation at $β=6.0$, 6.2 and 6.4 using the Wilson and the tree-level improved SW-Clover actions. We apply these renormalization constants to fully non-perturbatively estimate quark masses in

J. Maalampi, N. Romanenko

We consider the reaction ee ->qqQQ as a test of lepton number non-conservation in the framework of the left-right-symmetric electroweak model. The main contributions to this process are due to Majorana neutrino exchange in t-channel and doubly charged Higgs (Delta{--}) exchange in s-channel with a pair of right-handed weak bosons (WR) as intermediate state.

M. Vänttinen, L. Mankiewicz, E. Stein

Using the renormalon technique, we estimate higher-twist contributions in deeply virtual Compton scattering and in hard exclusive $π^0$ leptoproduction.

Ram Brustein, Merav Hadad

The origin of dark matter in the universe may be scalar particles produced by amplification of quantum fluctuations during a period of dilaton-driven inflation. We show, for the first time, that a single species of particles, depending on its mass and interactions, can be a source of both cold and hot dark matter simultaneously. Detection of such weakly inte

Stephen Godfrey, Tao Han, Pat Kalyniak

In a strongly-interacting electroweak sector with an isosinglet vector state, such as the techni-omega, $ω_T$, the direct $ ω_T Z γ$ coupling implies that an $ω_T$ can be produced by $Z γ$ fusion in $e γ$ collisions. This is a unique feature for high energy $e^+e^-$ or $e^-e^-$ colliders operating in an $eγ$ mode. We consider the processes $e^- γ\to e^- Zγ$

D. Gomez Dumm, A. Pich

The interplay between short- and long-distance contributions to the K_L-->mu+ mu- decay amplitude is analyzed. The long-distance piece is estimated using chiral perturbation theory techniques and large-N_C considerations, leading to a consistent description of the pi^0-->e+ e-, eta-->mu+ mu- and K_L-->mu+ mu- branching ratios.

Jochen Biebel

The effects of CP violating anomalous ZZZ and gammaZZ vertices in ZZ production are determined. We present the differential cross-section for e+e- -> ZZ with dependence on the spins of the Z bosons. It is shown that from the different spin combinations those with one longitudinally and one transversally polarized Z in the final state are the most sensitive t

V. L. Eletsky, B. L. Ioffe, J. I. Kapusta

The mass shift and width broadening of $ρ$-mesons produced in heavy ion collisions is estimated. It is found that the mass increases by some tens of MeV but the width becomes large, increasing by 200 MeV at beam energies of a few GeV$\cdot$A and by twice that amount at beam energies of about a hundred GeV$\cdot$A.

Yosef Nir

This is a written version of a series of three lectures aimed at graduate students in the field of experimental high energy physics. The emphasis is on physics that is relevant to $B$-factories. The main topics covered are: (i) The flavor sector of the Standard Model; (ii) Determination of the mixing parameters; (iii) CP violation in meson decays (a model in

A. Gomez Nicola, D. A. Steer

We study bosonisation in the massive Thirring and sine-Gordon models at finite temperature T and nonzero fermion chemical potential $μ$. For that purpose we use both canonical operator and path integral approaches, paying particular attention to the issues of thermal normal ordering and renormalisation. At T>0 and $μ=0$, the massive Thirring model bosonises

John Ellis, N. E. Mavromatos, D. V. Nanopoulos

We consider cosmology in the framework of a `material reference system&#39; of D particles, including the effects of quantum recoil induced by closed-string probe particles. We find a time-dependent contribution to the cosmological vacuum energy, which relaxes to zero as $\sim 1/ t^2$ for large times $t$. If this energy density is dominant, the Universe expa

G. Kälbermann, H. Halevi

It is shown that if our visible universe is a thin trapped shell in a five-dimensional universe, all matter in it may be connected almost instantaneously through the fifth dimension. What appears to be action at a distance is then understood as undetectable ultrafast communication.

G. N. C. Kirby, R. Morrison, D. W. Stemple

Reflective systems allow their own structures to be altered from within. Here we are concerned with a style of reflection, called linguistic reflection, which is the ability of a running program to generate new program fragments and to integrate these into its own execution. In particular we describe how this kind of reflection may be provided in the compile

U. H. E. Hansmann, Y. Okamoto, J. Onuchic

We study the free energy landscape of the small peptide Met-enkephalin. Our data were obtained from a generalized-ensemble Monte Carlo simulation taking the interactions among all atoms into account. We show that the free energy landscape resembles that of a funnel, indicating that this peptide is a good folder. Our work demonstrates that the energy landscap

Jeroen van den Brink, Daniel Khomskii

We consider the double-exchange for systems in which doped electrons occupy degenerate orbitals, treating the realistic situation with double degenerate $e_g$ orbitals. We show that the orbital degeneracy leads in general to formation of anisotropic magnetic structures and that in particular, depending on the doping concentration, the layered magnetic struct

Matthew G. Sexton, Joshua E. S. Socolar, David G. Schaeffer

We study a scalar lattice model for inter-grain forces in static, non-cohesive, granular materials, obtaining two primary results. (i) The applied stress as a function of overall strain shows a power law dependence with a nontrivial exponent, which moreover varies with system geometry. (ii) Probability distributions for forces on individual grains appear Gau

Carlos P. Herrero

Quantum effects on the atom delocalization in amorphous silicon have been studied by path-integral Monte Carlo simulations from 30 to 800 K. The quantum delocalization is appreciable vs. topological disorder, as seen from structural observables such as the radial distribution function (RDF). At low temperatures, the width of the first peak in the RDF increas

Stefan Goedecker

Methods exhibiting linear scaling with respect to the size of the system, so called O(N) methods, are an essential tool for the calculation of the electronic structure of large systems containing many atoms. They are based on algorithms which take advantage of the decay properties of the density matrix. In this article the physical decay properties of the de

Alberto Berretti, Guido Gentile

For the standard map the homotopically non-trivial invariant curves of rotation number satisfying the Bryuno condition are shown to be analytic in the perturbative parameter, provided the latter is small enough. The radius of convergence of the Lindstedt series -- sometimes called critical function of the standard map -- is studied and the relation with the

P. Yiou, D. Sornette, M. Ghil

Using multi-scale ideas from wavelet analysis, we extend singular-spectrum analysis (SSA) to the study of nonstationary time series of length $N$ whose intermittency can give rise to the divergence of their variance. SSA relies on the construction of the lag-covariance matrix C on M lagged copies of the time series over a fixed window width W to detect the r

Marc Davis, Sandra M. Faber

A second generation spectrograph for the Keck telescope is under construction at the Lick Observatory shops and will be delivered to Hawaii in 1999. Starting in the Fall of 1999, we shall begin the second phase of the DEEP project: a dense redshift survey of galaxies at Z=1. With each pointing of DEIMOS we shall obtain simultaneous short slit spectra of 70-1

Christopher W. Stubbs

Microlensing surveys search for the transient brightening of a background star that is the signature of gravitational lensing by a foreground compact object. This technique is an elegant way to search for astrophysical candidates that might comprise the dark matter halo of the Milky Way. While the current projects have successfully detected the phenomenon of

D. E. Reichart, F. J. Castander, R. C. Nichol

We present a Bayesian inference analysis of the Markevitch (1998) and Allen & Fabian (1998) cooling flow corrected X-ray cluster temperature catalogs that constrains the slope and the evolution of the empirical X-ray cluster luminosity-temperature (L-T) relation. We find that for the luminosity range 10^44.5 erg s^-1 < L_bol < 10^46.5 erg s^-1 and the redshi

Alberto Buzzoni

The problem of UV properties of primeval galaxies is briefly assessed from the theoretical point of view discussing its impact on the definition of the cosmological model.

Margo F. Aller, Hugh D. Aller, Philip A. Hughes, George E. Latimer

Results from a long-term program to quantify the range of behavior of the cm-wavelength total flux and linear polarization variability properties of a sample of 41 radio-loud BL Lac objects using weekly to tri-monthly observations with the University of Michigan 26-m telescope operating at 14.5, 8.0, and 4.8 GHz are presented; these observations are used to

Matthew J. Benacquista

Space-based gravitational wave detectors will have the ability to observe continuous low frequency gravitational radiation from binary star systems. They can determine the direction to continuous sources with an angular resolution approaching tens of arcminutes. This resolution should be sufficient to identify binary sources as members of some nearby globula

G. Amelino-Camelia, John Ellis, N. E. Mavromatos, D. V. Nanopoulos

We discuss possible signatures of quantum gravity for the propagation of light, including an energy-dependent velocity (refractive index), dispersion in velocity at a given energy, and birefringence. We also compare the sensitivities of different astrophysical observations, including BATSE data on GRB 920229, BeppoSAX data on GRB 980425, the possible HEGRA o

H. J. Martinez, M. E. Merchan, C. A. Valotto, D. G. Lambas

We compute quasar-galaxy and AGN-galaxy cross-correlation functions for samples taken from the \cite{VCV98} catalog of quasars and active galaxies, using tracer galaxies taken from the Edinburgh/Durham Southern Catalog. The sample of active galaxy targets shows positive correlation at projected separations $r_p < 6 h^{-1} Mpc$ consistent with the usual power

Rick Edelson, Kirpal Nandra

During 1997 March-July, XTE observed the bright, strongly variable Seyfert 1 galaxy NGC 3516 once every ~12.8 hr for 4.5 months and nearly continuously (with interruptions due to SAA passage but not Earth occultation) for a 4.2 day period in the middle. These were followed by ongoing monitoring once every ~4.3 days. These data are used to construct the first

B. Altieri, L. Metcalfe, J. P. Kneib, B. McBreen

We present results of ultra-deep ISOCAM observations through a cluster-lens at 7 and 15 micron with the Infrared Space Observatory (ISO) satellite. These observations reveal a large number of luminous Mid-Infrared (MIR) sources. Cross-identification in the optical and Near-Infrared (NIR) wavebands shows that about half of the 7 micron sources are cluster gal

Bradley E. Schaefer

Explosive astrophysical events at high red shift can be used to place severe limits on the fractional variation in the speed of light ($Δc/c$), the photon mass ($m_γ$), and the energy scale of quantum gravity ($E_{QG}$). I find $Δc/c < 6.3 \times 10^{-21}$ based on the simultaneous arrival of a flare in GRB 930229 with a rise time of $220 \pm 30 μs$ for phot

J. Delabrouille, J. -L. Puget, R. Gispert, J. -M. Lamarre

This paper discusses the problem of the optimisation of the scanning strategy for the Planck mission.