April 1998 arXiv papers — page 13

K. Pinn, C. Wieczerkowski

There are 880 magic squares of size 4 by 4, and 275,305,224 of size 5 by 5. It seems very difficult if not impossible to count exactly the number of higher order magic squares. We propose a method to estimate these numbers by Monte Carlo simulating magic squares at finite temperature. One is led to perform low temperature simulations of a system with many gr

Hualin Shi, Wei-Mou Zheng

By including the contribution of the thermal cloud to the Lagrangian of the condensate of a Bose gas, we extend the time-dependent variational method at zero temperature to study temperature-dependent low collective excitation modes. A Gaussian trial wave function of the condensate and a static distribution density of the thermal cloud are used, and analytic

Z. Tsvetanov, R. Morganti, R. A. E. Fosbury, M. G. Allen

We have collected emission line ([Oiii] 5007 and Halpha+[Nii]) and radio continuum images for a volume limited (cz <= 3600 km/s) sample of southern Seyfert galaxies. The optical data were obtained at ESO using the 2.2 m, NTT and 3.6 m telescopes, and have a typical resolution of 1&#34; and noise level of ~1e-16 ergs cm-2 s-1 arcsec-2. The radio continuum obs

Phillip Helbig

Recently, Park & Gott claimed that there is a statistically significant, strong, negative correlation between the image separation and source redshift for gravitational lenses. This is somewhat puzzling if one believes in a flat (k = 0) universe, since in this case the typical image separation is expected to be independent of the source redshift, while one e

G. Fossati, L. Maraschi, A. Celotti, A. Comastri

We collect data from the radio to the gamma-ray range for three complete samples of blazars: the Slew Survey and the 1Jy samples of BL Lacs and the 2Jy sample of Flat Spectrum Radio-Loud Quasars (FSRQs). The fraction of objects detected in gamma-rays (E > 100 MeV) is 17%, 26% and 40% in the three samples respectively. Except for the Slew Survey sample, gamma

G. Fossati, L. Chiappetti

The blazar Mkn 421 has been observed, as part of the AO1 Core Program, five times from 2 to 7 May 1997. In the LECS+MECS energy band the spectrum shows convex curvature, well represented by a broken power--law. Flux variability (more than a factor 2) has been detected over the entire 0.1--10 keV range, accompanying which the spectrum steepens with the decrea

L. Maraschi

I describe a general framework that could allow to understand the broad band spectra of blazars and lead to a unified picture of the emission from relativistic jets, in BL Lac objects as well as in flat spectrum, radio loud Quasars. The scheme serves as a useful basis to introduce and discuss some of the most in teresting results so far obtained on Blazars w

Ethan Schreier, Alessandro Marconi, David Axon, Nicola Caon

We report HST NICMOS observations of the central region of NGC 5128 at 2.2mic and in Paschen Alpha (PA). The continuum images show extended emission typical of an elliptical galaxy and a strong unresolved central source we identify as the nucleus of the galaxy. Its position is consistent with ground-based IR and radio data, and with the peak of reddening fou

W. Bednarek

Multiwavelength observations of high energy flare in 1996 from 3C 279 seems to favour the so called mirror model between different inverse Compton scattering models proposed as a possible explanation of gamma-ray emission in blazars. We performed kinematic analysis of the relativistic blob - mirror system and found that only part of the mirror located very c

Maciej Konacki, Andrzej J. Maciejewski, Alex Wolszczan

In this paper we present a new method that can be used for analysis of time of arrival of a pulsar pulses (TOAs). It is designated especially to detect quasi-periodic variations of TOAs. We apply our method to timing observations of PSR B1257+12 and demonstrate that using it it is possible to detect not only first harmonics of a periodic variations, but also

E. Carretta, C. Cacciari, F. R. Ferraro, F. Fusi Pecci

New BVI CCD photometry is presented for 60 RR Lyrae variables in the globular cluster M3. Light curves have been constructed and ephemerides have been (re)-derived for all of them. Four stars (i.e. V29, V136, V155 and V209), although recognized as variables, had no previous period determinations. Also, the period derived for V129 is significantly different f

B. J. Boyle

We present proposed ground-based support observations at the AAO for the forthcoming Hubble Deep Field South (HDF-S) campaign.

Matthew A. Bershady, James D. Lowenthal, David C. Koo

We have used the Keck 10m telescope to count objects as a function of image size in 2 high galactic latitude fields covering 1.5 arcmin^2 and reaching 50% completeness at K=24 and J=24.5 for stellar sources. Counts extend ~1 mag deeper in K than surveys with other telescopes; complement Keck surveys providing counts at comparable or shallower depths but not

Carlos De Breuck, M. S. Brotherton, Hien D. Tran, Wil van Breugel

We report the discovery of WN J0717+4611, a highly polarized red quasar at z=1.462, selected from a sample of faint (S_{1.4GHz} > 10 mJy) ultra steep spectrum (alpha < -1.3) radio sources. VLA observations at 4.85 GHz show that the radio source is dominated by a 21 mJy core. Using the Keck telescopes, we obtained spectra with a combined wavelength range cove

Nemanja Kaloper

We compute the entropy of extremal black strings in three dimensions, using Strominger&#39;s approach to relate the Anti-de-Sitter near-horizon geometry and the conformal field theory at the asymptotic infinity of this geometry. The result is identical to the geometric Bekenstein-Hawking entropy. We further discuss an embedding of three-dimensional black str

J Alberto Lobo, Miquel Montero

In this paper we design and develop several filtering strategies for the analysis of data generated by a resonant bar Gravitational Wave (GW) antenna, with the goal to assess the presence (or absence) in them of long duration monochromatic GW signals, as well as their eventual amplitude and frequency, within the sensitivity band of the detector. Such signals

H. Weigel

Within an extended Skyrme soliton model for baryons the interplay between the collective radial motion and the SU(3)--flavor--rotations is investigated. The coupling between these modes is mediated by flavor symmetry breaking. Collective coordinates which describe the corresponding large amplitude fluctuations are introduced and treated canonically. When dia

Andreas Gathmann

In the first part of the paper, we give an explicit algorithm to compute the (genus zero) Gromov-Witten invariants of blow-ups of an arbitrary convex projective variety in some points if one knows the Gromov-Witten invariants of the original variety. In the second part, we specialize to blow-ups of P^r and show that many invariants of these blow-ups can be i

Louis Funar

The aim of this paper (inspired from a problem of Habegger) is to describe the set of cubical decompositions of compact manifolds mod out by a set of combinatorial moves analogous to the bistellar moves considered by Pachner, which we call bubble moves. One constructs a surjection from this set onto the the bordism group of codimension one immersions in the

T. Gilbert, J. R. Dorfman

We generalize Gaspard&#39;s method for computing the ε-entropy production rate in Hamiltonian systems to dissipative systems with attractors considered earlier by Tél, Vollmer, and Breymann. This approach leads to a natural definition of a coarse grained Gibbs entropy which is extensive, and which can be expressed in terms of the SRB measures and volumes of

A. Trovato, J. van Mourik, A. Maritan

A lattice model of a hetero-polymer with random hydrophilic-hydrophobic charges interacting with the solvent is introduced, whose continnuum counterpart has been proposed by T. Garel, L. Leibler and H. Orland {J. Phys. II France 4, 2139 (1994)]. The transfer matrix technique is used to study various constrained annealed systems which approximate at various d

P. Gaspard, R. Klages

We study the consequences of deterministic chaos for diffusion-controlled reaction. As an example, we analyze a diffusive-reactive deterministic multibaker and a parameter-dependent variation of it. We construct the diffusive and the reactive modes of the models as eigenstates of the Frobenius-Perron operator. The associated eigenvalues provide the dispersio

Tsutomu Momoi, Kenn Kubo

We study the ferromagnetism due to orbital degeneracy in the Hubbard model in infinite dimensions. The model contains the intraorbital repulsion $U$, the interorbital repulsion $U^\prime$, the exchange $J$ (Hund coupling) and the pair hopping $J^\prime$, where all of them originate from the on-site Coulomb interaction. The ground state of the effective one-s

H. Dorn

The formal extension of the T-duality rules for open strings from Abelian to non-Abelian gauge field background leads in a well known manner to the notion of matrix valued D-brane position. The application of this concept to the non-Abelian gauge field RG $\beta $-function of the corresponding $\sigma $-model yields a mass term in the gauge field dynamics on

Gabriel Lopes Cardoso

We consider four-dimensional charged black-holes occuring in toroidally compactified heterotic string theory, whose ten-dimensional interpretation involves a Kaluza-Klein monopole and a five-brane. We show that these four-dimensional black-holes can be connected to two-dimensional charged heterotic black-holes upon removal of the constants appearing in the h

Jin Hong, Seok-Jin Kang, Tetsuji Miwa, Robert Weston

We consider the analogue of the 6-vertex model constructed from alternating spin n/2 and spin m/2 lines, where $1\leq n<m$. We identify the transfer matrix and the space on which it acts in terms of the representation theory of $U_q(sl_2)$. We diagonalise the transfer matrix and compute the S-matrix. We give a trace formula for local correlation functions. W

Neil Humphreys, David Matravers, Roy Maartens

We construct an exact relativistic cosmology in which an inhomogeneous but isotropic local region has fractal number counts and matches to a homogeneous background at a scale of the order of $10^2$ Mpc. We show that Einstein&#39;s equations and the matching conditions imply either a nonlinear Hubble law or a very low large-scale density.

Ben O&#39;Shaughnessy, Dimitrios Vavylonis

We study A-B reaction kinetics at a fixed interface separating A and B bulks. Initially, the number of reactions ${\cal R}_t \sim t n_A^\infty n_B^\infty$ is 2nd order in the far-field densities $n_A^\infty,n_B^\infty$. First order kinetics, governed by diffusion from the dilute bulk, onset at long times: ${\cal R}_t\approx x_t n_A^\infty$ where $x_t\sim t^{

K. Saito, K. Tsushima, AW Thomas, AG Williams

The propagation of the scalar ($\sigma$) and vector ($\omega$) mesons in nuclear matter is studied in detail using the Walecka model over a wide range of densities and including the effects of a finite $\sigma$ width through the inclusion of a two-pion loop. We calculate the dispersion relation and spectral functions of the $\sigma$ and (transverse and longi

J. Springael, R. Conte, M. Musette

It has recently been argued that there might exist a four-parameter analytic solution to the Bianchi IX cosmological model, which would extend the three-parameter solution of Belinskii et al. to one more arbitrary constant. We perform the perturbative Painlevé test in the proper time variable, and confirm the possible existence of such an extension.

Jonas Blom, Edwin Langmann

We find and solve a large class of integrable dynamical systems which includes Calogero-Sutherland models and various novel generalizations thereof. In general they describe $N$ interacting particles moving on a circle and coupled to an arbitrary number, $m$, of $su(N)$ spin degrees of freedom with interactions which depend on arbitrary real parameters $x_j$

G. M. D&#39;Ariano, C. Macchiavello, L. Maccone

We show the feasibility of a tomographic reconstruction of Schrödinger cat states generated according to the scheme proposed by S. Song, C.M. Caves and B. Yurke [Phys. Rev. A 41, 5261 (1990)]. We present a technique that tolerates realistic values for quantum efficiency at photodetectors. The measurement can be achieved by a standard experimental setup.

C. Jung, M. Mueller, I. Rotter

We consider the behaviour of open quantum systems in dependence on the coupling to one decay channel by introducing the coupling parameter $α$ being proportional to the average degree of overlapping. Under critical conditions, a reorganization of the spectrum takes place which creates a bifurcation of the time scales with respect to the lifetimes of the reso

Arun Kumar Pati

After a measurement, to observe the relative phases of macroscopically distinguishable states we have to ``undo&#39;&#39; a quantum measurement. We generalise an earlier model of Peres from two state to N-state quantum system undergoing measurement process and discuss the issue of observing relative phases of different branches. We derive an inequality which

Paul J. Werbos

This paper provides mathematical details related to another new paper which suggests: (1) new approaches to the analysis of soliton stability; (2) families of Lagrangian field theories where solitons might possibly exist even without topological charge; (3) alternative approaches to quantizing solitons, with testable nuclear implications. This paper evaluate

G. Q. Li, G. E. Brown

We study $K^+$ and $Λ$ flow in heavy-ion collisions at beam energies of about 2A GeV. We present our results in both the `traditional&#39; (i.e., in terms of the average transverse momentum in the reaction plane) as well as `modern&#39; (i.e., in terms of coefficients of the Fourier analysis of azimuthal distributions) methods of flow analysis. We find signi

D. E. Kahana, S. H. Kahana

A two phase cascade is presented for the treatment of ultra-high energy ion-ion collisions at energies from 17-200 GeV. First a high energy, fast cascade is performed, in which original baryons and freed hard partons, if any, collide. This stage ignores energy loss from soft (slow) processes. In this first version no hard processes, aside from Drell-Yan prod

M. Thoresen, P. Navratil, B. R. Barrett

Different techniques for calculating effective operators within the framework of the shell model using the same effective interaction and the same excitation spaces are presented. Starting with the large-basis no-core approach, we compare the time-honored perturbation-expansion approach and a model-space truncation approach. Results for the electric quadrupo

Greg Martin

We derive an upper bound for the least number of variables needed to guarantee that a system of t quadratic forms (t>=2) over a field F has a nontrivial zero. In particular, if F is a local field, then 2t^2+3 variables insure the existence of a nontrivial zero (2t^2+1 if t is even), while if F=Q_p with p>=11, then 2t^2-2t+5 variables suffice (2t^2-2t+1 if 3

Chin-Lung Wang

We show that birational smooth complex projective varieties with numerically effective canonical bundles along the exceptional loci have the same Betti numbers. In particular, birational smooth minimal models share the same Betti numbers. Our methods indicate a link between $p$-adic measure and the minimal model theory.

Kalle Karu

We consider a class of stable smoothable n-dimensional varieties, the analogs of stable curves. Assuming the minimal model program in dimension n+1, we prove that this class is bounded. From Kollar&#39;s method of constructing projective moduli spaces we get as a corollary that minimal model program in dimension n+1 implies the existence of a projective coar

Mauro C. Beltrametti, Alan Howard, Michael Schneider, Andrew J. Sommese

Let $X\subset P^N$ be an n-dimensional connected projective submanifold of projective space. Let $p : P^N\to P^{N-q-1}$ denote the projection from a linear $P^q\subset P^N$. Assuming that $X\not\subset P^q$ we have the induced rational mapping $ψ:=p_X: X\to P^{N-q-1}$. This article started as an attempt to understand the structure of this mapping when $ψ$ ha

Louis Funar

We prove that the image of the mapping class group by the representations arising in the SU(2)-TQFT is infinite, provided that the genus is bigger than 2 and the level r of the theory is different from 2,3,4,6. In particular the quotient of the mapping class group by the normaizer of the r-th power of a Dehn twist is infinite if the genus is at least 3 and r

Greg Martin

Every positive rational number has representations as Egyptian fractions (sums of reciprocals of distinct positive integers) with arbitrarily many terms and with arbitrarily large denominators. However, such representations normally use a very sparse subset of the positive integers up to the largest demoninator. We show that for every positive rational there

R. Vershynin

Absolutely representing system (ARS) in a Banach space $X$ is a set $D \subset X$ such that every vector $x$ in $X$ admits a representation by an absolutely convergent series $x = \sum_i a_i x_i$ with $(a_i)$ reals and $(x_i) \subset D$. We investigate some general properties of ARS. In particular, ARS in uniformly smooth and in B-convex Banach spaces are ch

Denis Uglov

An action of the Yangian of the general Lie algebra gl(N) is defined on every irreducible integrable highest weight module of affine gl(N) with level greater than 1. This action is derived, by means of the Drinfeld duality and a subsequent semi-infinite limit, from a certain induced representation of the degenerate double affine Hecke algebra H. Each vacuum

Nima Arkani-Hamed, Riccardo Rattazzi

We consider strongly coupled supersymmetric gauge theories softly broken by the addition of gaugino masses $m_λ$ and (non-holomorphic) scalar masses $m^2$, taken to be small relative to the dynamical scale $Λ$. For theories with a weakly coupled dual description in the infrared, we compute exactly the leading soft masses for the &#34;magnetic&#34; degrees of

Esko Keski-Vakkuri, Per Kraus

Polchinski and Pouliot have shown that M-momentum transfer between membranes in supergravity can be understood as a non-perturbative instanton effect in gauge theory. Here we consider a dual process: electric flux transmission between D-branes. We show that this process can be described in perturbation theory as virtual string pair creation, and is closely r

Csaba Csaki, Hitoshi Murayama

We discuss the effects of instantons in partially broken gauge groups on the low-energy effective gauge theory. Such effects arise when some of the instantons of the original gauge group G are no longer contained in (or can not be gauge rotated into) the unbroken group H. In cases of simple G and H, a good indicator for the existence of such instantons is th

Jacqueline Faridani, Smaragda Lola, Patrick J. O&#39;Donnell, Utpal Sarkar

We study the scale at which one can generate the lepton asymmetry of the universe which could then get converted to a baryon asymmetry during the electroweak phase transition. We consider the possibility that the Yukawa couplings are small but sufficiently large to generate enough lepton asymmetry. This forbids the possibility of the $(B-L)$ breaking scale b

Subhendra Mohanty, Utpal Sarkar

We point out that a background torsion field will produce an effective potential to the $K$ and $\bar{K}$ with opposite signs. This allows us to constrain the background torsion field from the $K_L$ and $K_S$ mass difference, CPT violating $K^\circ$ and $\bar{K^\circ}$ mass difference and the CP violating quantities $ε$ and $η_{+-}$. The most stringent bound

Chong Sheng Li, P. Nadolsky, C. -P. Yuan, Hong-Yi Zhou

If a light gluino, with a mass of the order of GeV, exists in the minimal supersymmetric extension of the Standard Model, then it can contribute to the production rate of the top quark pairs at hadron colliders via the process gluino + gluino --> t + tbar. Because the top quark is heavy, the masses of the superpartners of the left-handed and right-handed top

Samim Erhan, Peter E. Schlein

We show that a triple-Regge parametrization of inclusive single diffraction agrees with the data in the following two domains: (a) xi > 0.03 at all t, (b) |t| > 1 GeV^2 at all xi. Since the triple-Regge parametrization fails when applied to the full xi-t range of the total single-diffractive cross section, we conclude that damping occurs only at low-xi and l

Marek Pawlowski

The old Weyl&#39;s idea of scale recalibration freedom and the Infeld and van der Waerden (IW) ideas concerning geometrical interpretation of the natural spinor phase gauge symmetry are discussed in the context of moderm models of fundamental particle interactions. It is argued that IW gauge symmetry can be naturaly identified with U(1) symmetry of Weinberg-

M. Laine, K. Rummukainen

Non-perturbative lattice simulations have shown that there is no electroweak phase transition in the Standard Model for the allowed Higgs masses, m_H \gsim 75 GeV. In the Minimal Supersymmetric Standard Model, in contrast, it has been proposed that the transition should exist and even be strong enough for baryogenesis up to m_H ~ 105 GeV, provided that the l

Amol Dighe, Isard Dunietz, Robert Fleischer

It is well known that $\sin(2β)$, where $β$ is one of the angles of the unitarity triangle of the CKM matrix, can be determined in a theoretically clean way by measuring mixing-induced CP violation in the decay $B_d \to J/ψK_S$. Another clean extraction of this CKM angle is provided by the time-dependent angular distribution for the decay products of $B_d \t

Amol Dighe, Isard Dunietz, Robert Fleischer

Suggestions for efficiently determining the lifetimes and mass difference of the light and heavy $B_s$ mesons ($B_s^L, B_s^H$) from $B_s \to J/ ψϕ, D_s^{*+}D_s^{*-}$ decays are given. Using appropriate weighting functions for the angular distributions of the decay products (moment analysis), one can extract $(Γ_H, Γ_L, Δm)_{B_s}$. Such a moment analysis allo

S. Bilke, Z. Burda, A. Krzywicki, B. Petersson

Four-dimensional simplicial quantum gravity is modified either by coupling it to U(1) gauge fields or by introducing a measure weighted by the orders of the triangles. Strong coupling expansion and Monte Carlo simulations are used. Although the two modifications of the standard pure-gravity model are apparently very distinct, they produce strikingly similar

Matteo Beccaria, Giuseppe Curci, Erika D&#39;Ambrosio

We study the numerical simulation of supersymmetric models having a local Nicolai map. The mapping can be regarded as a stochastic equation and its numerical integration provides an algorithm for the simulation of the original model. In this paper, the method is discussed in details and applied to examples in 0+1 and 1+1 dimensions.

Leonard Parker

I consider certain renormalization effects in curved spacetime quantum field theory. In the very early universe these effects resemble those of a cosmological constant, while in the present universe they give rise to a significant finite renormalization of the gravitational constant. The relevant renormalization term and its relation to elementary particle m

A. Tanguy, M. Gounelle, S. Roux

We study the effect of long-range elastic interactions in the dynamical behavior of an elastic chain driven quasi-statically in a quenched random pinning potential and in the strong pinning limit. This is a generic situation occuring in solid friction, crack propagation, wetting front motion, ... Tuning the exponent of the algebraic decay of the elastic inte

Walter Kob, Jean-Louis Barrat

This is a Reply to the Comment of Muessel and Rieger cond-mat/9804063 to out paper on ``Aging Effects in a Lennerd-Jones Glass&#39;&#39;. We show that the scaling function proposed by Muessel and Rieger does not lead to a satisfactory scaling of our aging data.

Luis A. N. Amaral, Martin Meyer

We introduce a new model for large scale evolution and extinction in which species are organized into food chains. The system evolves by two processes: origination/speciation and extinction. In the model, extinction of a given species can be due to an externally induced change in the environment or due to the extinction of all preys of that species (co-extin

Eric Cockayne, Karin M. Rabe

In this article, we motivate the detailed comparison of the physical properties of individual configurations of a ferroelectric solid solution as a means toward developing first principles models for these systems. We compare energies, dielectric constants epsilon_infinity, mode effective charges of local polar distortions, and the zero temperature piezoelec

Youngki Lee, Luis A. N. Amaral, David Canning, Martin Meyer

We analyze the fluctuations in the gross domestic product (GDP) of 152 countries for the period 1950--1992. We find that (i) the distribution of annual growth rates for countries of a given GDP decays with ``fatter&#39;&#39; tails than for a Gaussian, and (ii) the width of the distribution scales as a power law of GDP with a scaling exponent $β\approx 0.15$.

G. Biroli, R. Monasson

The Glauber dynamics of the Hopfield model at low storage level is considered. We analytically derive the spectrum of relaxation times for large system sizes. The longest time scales are gathered in families, each family being in one to one correspondence with a stationary (not necessarily stable) point of the static mean-field free-energy. Inside a family,

Nikolai V. Prokof&#39;ev, Boris V. Svistunov

We present a precise solution of the polaron problem by a novel Monte Carlo method. Basing on conventional diagrammatic expansion for the Green function of the polaron, $G({\bf k}, τ)$, we construct a process of generating continuous random variables ${\bf k}$ and $τ$, with the distribution function exactly coinciding with $G({\bf k}, τ)$. The polaron spectr

E. K. Lenzi, L. C. Malacarne, R. S. Mendes

A unified presentation of the perturbation and variational methods for the generalized statistical mechanics based on Tsallis entropy is given here. In the case of the variational method, the Bogoliubov inequality is generalized in a very natural way following the Feynman proof for the usual statistical mechanics. The inequality turns out to be form-invarian

L. R. Evangelista, L. C. Malacarne, R. S. Mendes

The classical limit for generalized partition functions is obtained using coherent states. In this framework it is presented a general procedure to obtain all the corrections to the classical limit. In particular, the first and second order quantum corrections are worked out explicitly, and the classical limit for the Tsallis thermostatistics is determined.

P. G. Silvestrov

Edge effects in the depinned phase of flux lines in hollow superconducting cylinder with columnar defects and electric current along the cylinder are investigated. Far from the ends of the cylinder vortices are distributed almost uniformly (delocalized). Nevertheless, near the edges these free vortices come closer together and form well resolved dense bunche

Claudius Gros, Ralph Werner

We reconsider the Cross and Fischer approach to spin-Peierls transitions. We show that a soft phonon occurs only if Omega_0<2.2 T_SP. For CuGeO_3 this condition is not fulfilled and the calculated temperature dependence of the Peierls-active phonon modes is in excellent agreement with experiment. A central peak of a width ~0.2 meV is predicted at T_SP. Good

S. A. Suslov, A. J. Roberts

A lubrication model describes the dynamics of a thin layer of fluid spreading over a solid substrate. But to make forecasts we need to supply correct initial conditions to the model. Remarkably, the initial fluid thickness is not the correct initial thickness for the lubrication model. Theory recently developed in \cite{Roberts89b,Roberts97b} provides the co

In-Saeng Suh, Chul H. Lee

The conversion of neutron matter into strange matter in a neutron star occurs through the non-leptonic weak-interaction process. We study the energy loss of the neutron star by the emission of axions in that process. Owing to that process, the neutron star will liberate the energy which can in no way be negligible as an axion burst.

In-Saeng Suh, G. J. Mathews

We have computed finite temperature corrections to the electron-hadron scattering cross sections. These are based upon the renormalized electron mass and the modified density of states due to the presence of a background thermal bath. It is found that the electron-hadron thermal transport scattering cross section can be much larger than the zero temperature

Piet Hut

Stellar dynamics is almost unreasonably well suited for an implementation in terms of special-purpose hardware. Unlike the case of molecular dynamics, stellar dynamics deals exclusively with a long-range force, gravity, which leads to a computational cost scaling as the square of the number of stars involved. While special tricks can lead to a reduction of t

L. Lemonon, M. Pierre, C. J. Cesarsky, D. Elbaz

We have imaged the inner square arcminute of the well known lensing and cooling flow cluster A2390 (z = 0.23) down to a sensitivity of 65 and 130 microJy at 6.75 and 15 micronmetre, respectively. We report the first evidence of an active star-forming region in a cooling flow (at those wavelengths) and strong emission in the mid-IR from lensed galaxies locate

A. A. Shaker, G. Longo, P. Merluzzi

We find a strong correlation between the effective radius of the largest early-type galaxies in compact groups of galaxies and the velocity dispersion of the groups. The lack of a similar correlation for late type galaxies is supportive of the so called second generation merging scenario which predicts that ellipticals should dominate the internal dynamics o

Julien E. G. Devriendt, Shiv K. Sethi, Bruno Guiderdoni, Biman B. Nath

We estimate the evolution of the contribution of galaxies to the cosmic background flux at $912 Å$ by means of a semi-analytic model of galaxy formation and evolution. Such a modelling has been quite successful in reproducing the optical properties of galaxies. We assume hereafter the high-redshift damped Lyman-$α$ (DLA) systems to be the progenitors of pres

A. Cappi, C. Benoist, L. N. da Costa, S. Maurogordato

We perform a fractal analysis of the Southern Sky Redshift Survey 2, following the methods prescribed by Pietronero and collaborators, to check their claim that the galaxy distribution is fractal at all scales, and we discuss and explain the reasons of some controversial points, through tests on both galaxy samples and simulations. We confirm that the amplit

B. J. Boyle, O. Almaini, I. Georgantopoulos, A. J. Blair

We report on the discovery of a narrow-emission-line object at z=0.672 detected in a deep ASCA survey. The object, AXJ0341.4-4453, has a flux in the 2--10keV band of 1.1+/-0.27 E-13 erg/s/cm**2, corresponding to a luminosity of 1.8E44 erg/s (q0=0.5, $H0 = 50km/s/Mpc. It is also marginally detected in the ROSAT 0.5-2keV band with a flux 5.8E-15 erg/s/cm**2. B

Ue-Li Pen

Defect models have recently been declared dead (Watson 1997), because they predict microwave background and matter fluctuations grossly out of line with what we see. In this talk we apply the fact that many defects are automatically destroyed at the time of radiation-matter transition, thus resurrecting the defects model. Moreover, the resurrected version pr

Neta A. Bahcall, Xiaohui Fan

How much matter is there in the universe? Does the universe have the critical density needed to stop its expansion, or is the universe underweight and destined to expand forever? We show that several independent measures, especially those utilizing the largest bound systems known - clusters of galaxies - all indicate that the mass-density of the universe is

Niranjan Ramachandran

We define Albanese and Picard 1-motives of smooth (simplicial) schemes over a perfect field. For smooth proper schemes, these are the classical Albanese and Picard varieties. For a curve, these are t he homological 1-motive of Lichtenbaum and the motivic $H^1$ of Deligne. This paper proves a conjecture of Deligne about providing an algebraic description, via

Rami Entin, Jaume Gomis

We analyze the large $N$ spectrum of chiral primary operators of three dimensional fixed points of the renormalization group. Using the space-time picture of the fixed points and the correspondence between anti-de Sitter compactifications and conformal field theories we are able to extract the dimensions of operators in short superconformal multiplets. We wr

Andrzej Czarnecki, William J. Marciano

Two loop electroweak corrections to b --> s gamma decays are computed. Fermion and photonic loop effects are found to reduce R = BR(b --> s gamma)/BR(b --> c e nu) by 8+-2% and lead to the standard model prediction BR(B --> X_s gamma)=(3.28 +- 0.30)x10^-4 for inclusive B meson decays. Comparison of R^{theory} =(3.04 +- 0.25)x10^-3(1+0.10rho), where rho is a

Daniel Z. Freedman, Samir D. Mathur, Alec Matusis, Leonardo Rastelli

Conformal techniques are applied to the calculation of integrals on AdS(d+1) space which define correlators of composite operators in the superconformal field theory on the d-dimensional boundary. The 3-point amplitudes for scalar fields of arbitrary mass and gauge fields in the AdS supergravity are calculated explicitly. For 3 gauge fields we compare in det

Duiliu-Emanuel Diaconescu, Sergei Gukov

Three dimensional N=2 gauge theories with arbitrary gauge group and fundamental flavors are engineered from degenerations of Calabi-Yau four-folds. We show how Coulomb and Higgs branches emerge in the geometric picture. The analysis of instanton generated superpotentials unravels interesting aspects of the five-brane effective action in M theory.

T. S. Nunner, J. Schmalian, K. H. Bennemann

We investigate the interplay of the electron-phonon and the spin fluctuation interaction for the superconducting state of YBa$_2$Cu$_3$O$_{7}$. The spin fluctuations are described within the nearly antiferromagnetic Fermi liquid theory, whereas the phonons are treated using a shell model calculation of all phonon branches. The electron-phonon coupling is cal

A. A. Deriglazov, D. M. Gitman

A manifestly Poincare invariant formulations for $SO(1,10)$ and SO(2,9) superstring actions are proposed. The actions are invariant under a local fermionic $κ$-symmetry as well as under a number of global symmetries, which turn out to be on-shell realization of the known ``new supersymmetry`` S-algebra. Canonical quantization of the theory is performed and r

M. Teper

We calculate the mass spectra and string tensions of SU(2), SU(3), SU(4) and SU(5) gauge theories in 2+1 dimensions. We do so by simulating the corresponding lattice theories and then extrapolating dimensionless mass ratios to the continuum limit. We find that such mass ratios are, to a first approximation, independent of the number of colours and that the r

G. Wellein, H. Fehske, A. P. Kampf

We study the magnetic properties of a frustrated Heisenberg spin chain with a dynamic spin-phonon interaction. By Lanczos diagonalization, preserving the full lattice dynamics, we explore the non-adiabatic regime with phonon frequencies comparable to the exchange coupling energy which is e.g. the relevant limit for the spin-Peierls compound $CuGeO_3$. When c

Changhao Jin

Methods are described in the framework of light-cone expansion which allow one to determine the Cabibbo-Kobayashi-Maskawa matrix elements |V_ub| and |V_cb| from measurements of the differential decay rates as a function of the scaling variables in the inclusive semileptonic decays of B mesons. By these model-independent methods the dominant hadronic uncertai

Baruch Meerson

A selection problem that appears in the Lifshitz-Slyozov (LS) theory of Ostwald ripening is reexamined. The problem concerns selection of a self-similar distribution function (DF) of the minority domains with respect to their sizes from a whole one-parameter family of solutions. A strong selection rule is found via an account of fluctuations. Fluctuations pr

J. E. Naya, S. D. Barthelmy, L. M. Bartlett, N. Gehrels

The Gamma Ray Imaging Spectrometer (GRIS) recently observed the gamma-ray emission from the Galactic center region. We have detected the 1809 keV Galactic 26Al emission at a significance level of 6.8-sigma but have found no evidence for emission at 1173 keV and 1332 keV, expected from the decay chain of the nucleosynthetic 60Fe. The isotopic abundances and f

Johanna Erdmenger, Christian Rupp, Klaus Sibold

We investigate the superconformal transformation properties of Green functions with one or more insertions of the supercurrent in N=1 supersymmetric quantum field theories. These Green functions are conveniently obtained by coupling the supercurrent and its trace to a classical supergravity background. We derive flat space superconformal Ward identities from

Vicent J. Martinez, Maria-Jesus Pons-Borderia, Rana A. Moyeed, Matthew J. Graham

We introduce a statistical quantity, known as the $K$ function, related to the integral of the two--point correlation function. It gives us straightforward information about the scale where clustering dominates and the scale at which homogeneity is reached. We evaluate the correlation dimension, $D_2$, as the local slope of the log--log plot of the $K$ funct

M. Käning, B. P. Lavrov, A. S. Melnikov, J. Röpcke

For the first time the emission of the radiative dissociation continuum of the hydrogen molecule ($a^{3}Σ_{g}^{+} \to b^{3}Σ_{u}^{+}$ electronic transition) is proposed to be used as a source of information for the spectroscopic diagnostics of non-equilibrium plasmas. The detailed analysis of excitation-deactivation kinetics, rate constants of various collis

M. C. Abbati, A. Mania&#39;

We investigate the differential calculus defined by Ashtekar and Lewandowski on projective limits of manifolds by means of cylindrical smooth functions and compare it with the C^infty calculus proposed by Froehlicher and Kriegl in more general context. For products of connected manifolds, a Boman theorem is proved, showing the equivalence of the two calculi

Neil Humphreys, Roy Maartens, David Matravers

Physical (and weak) regularity conditions are used to determine and classify all the possible types of spherically symmetric dust spacetimes in general relativity. This work unifies and completes various earlier results. The junction conditions are described for general non-comoving (and non-null) surfaces, and the limits of kinematical quantities are given

V. D. Efros, W. Leidemann, G. Orlandini

A non-conventional approach to calculating reactions in quantum mechanics is presented. Reaction observables are obtained with bound state calculation techniques. The accuracy of the method to calculate few-nucleon response functions is discussed.