August 1997 arXiv papers — page 13

E. Brocato, S. Cassisi, V. Castellani

We present Very Low Mass stellar models as computed including non-grey model atmospheres for selected assumptions about the star metallicities. The role of atmospheres is discussed and the models are compared with models based on the Eddington approximation and with similar models appeared in the recent literature. Theoretical predictions concerning both the

R. G. Carlberg

The geometry of Freedman-Roberston-Walker cosmological models is fixed by the mass density parameter, Omega_M, and the cosmological constant, Omega_Lambda. The classical volume-redshift cosmological relation is a sensitive Omega=[Omega_M,Omega_Lambda] indicator but its redshift dependence is observationally degenerate with the luminosity or number density ev

G. H. Tovmassian, J. Greiner, F. -J. Zickgraf, P. Kroll

A new magnetic cataclysmic variable is identified as the counterpart of the X-ray source RX J0719.2+6557. The emission lines show radial velocity variations with a period of 98.2 min. This coincides with the period of deep eclipses (up to 4 mag) in the photometric light curve. The phase of the eclipse relative to the spectroscopic phase, and its structure in

A. Jorissen, S. Van Eck

The current understanding of the origin of barium and S stars is reviewed, based on new orbital elements and binary frequencies. The following questions are addressed: (i) Is binarity a necessary condition to produce a barium star? (ii) What is the mass transfer mode (wind accretion or RLOF?) responsible for their formation? (iii) Do barium stars form as dwa

A. D. Dolgov

Quantum field theory predicts that vacuum energy (or what is the same, cosmological constant) should be 50-100 orders of magnitude larger than the existing astronomical limit. A very brief review of possible solutions of this problem is presented. A mechanism of adjustment of vacuum energy down to (almost) zero by the back-reaction of massless vector or seco

J. Mora, C. Stephens, H. Waelbroeck

We argue that the phenomenon of symmetry breaking in genetics can enhance the adaptability of a species to changes in the environment. In the case of a virus, the claim is that the codon bias in the neutralization epitope improves the virus' ability to generate mutants that evade the induced immune response. We support our claim with a simple ``toy model

H. Waelbroeck

A survey of the patterns of synonymous codon preferences in the HIV env gene reveals a relation between the codon bias and the mutability requirements in different regions in the protein. At hypervariable regions in $gp120$, one finds a greater proportion of codons that tend to mutate non-synonymously, but to a target that is similar in hydrophobicity and vo

C. Stephens, I. Garcia, J. Mora, H. Waelbroeck

A theoretical and experimental analysis is made of the effects of self-adaptation in a simple evolving system. Specifically, we consider the effects of coding the mutation and crossover probabilities of a genetic algorithm evolving in certain model fitness landscapes. The resultant genotype-phenotype mapping is degenerate, there being no direct selective adv

O. Angeles, C. Stephens, H. Waelbroeck

In genetic systems there is a non-trivial interface between the sequence of symbols which constitutes the chromosome, or ``genotype'', and the products which this sequence encodes --- the ``phenotype''. This interface can be thought of as a ``computer''. In this case the chromosome is viewed as an algorithm and the phenotype as the re

Harry J. Lipkin

New results going beyond those obtained from isospin and flavor symmetry and subject to clear experimental tests are obtained for effects of FSI in $B^\pm$ decays to charmless strange final states containing neutral flavor-mixed mesons like $ω$, $ϕ$, $η$ and $η'$. The most general strong-interaction diagrams containing arbitrary numbers of quarks and glu

Thomas Schaefer

We study an interacting ensemble of instantons at finite baryon chemical potential. We emphasize the importance of fermionic zero modes and calculate the fermion induced interaction between instantons at non-zero chemical potential. We show that unquenched simulations of the instanton ensemble are feasible in two regimes, for sufficiently small and for very

R. Arnowitt, Pran Nath

The development of supergravity unified models and their implications for current and future experiments are discussed.

K. G. Chetyrkin, B. A. Kniehl, M. Steinhauser

If quantum chromodynamics (QCD) is renormalized by minimal subtraction (MS), at higher orders, the strong coupling constant alpha_s and the quark masses m_q exhibit discontinuities at the flavour thresholds, which are controlled by so-called decoupling constants, zeta_g and zeta_m, respectively. Adopting the modified MS (MS-bar) scheme, we derive simple form

Pushan Majumdar, H. S. Sharatchandra

We construct wave packets for the hydrogen atom labelled by the classical action-angle variables with the following properties. i) The time evolution is exactly given by classical evolution of the angle variables. (The angle variable corresponding to the position on the orbit is now non-compact and we do not get exactly the same state after one period. Howev

Sergio Ferrara, Murat Gunaydin

We give an invariant classification of orbits of the fundamental representations of exceptional groups $E_{7(7)}$ and $E_{6(6)}$ which classify BPS states in string and M theories toroidally compactified to d=4 and d=5. The exceptional Jordan algebra and the exceptional Freudenthal triple system and their cubic and quartic invariants play a major role in thi

Kostyantin Ilienko, Aleksandr A. Zheltukhin

An application of the Newman-Penrose dyad formalism for description of tensionless (null) string dynamics in 4D Minkowski spacetime is studied in a background of antisymmetric fields. We present a special class of background antisymmetric fields which admits exact solutions of the null string motion equations and formulate a sufficient condition of the absen

Gerald B. Cleaver

I review findings of various research groups regarding perturbative heterotic string model building in the last 12 months. Attention is given to recent studies of extra U(1)'s and local discrete symmetries (LDS's) in generic string models. Issues covered include the role of U(1)'s and LDS's in limiting proton decay, developments in classifica

B. C. Allanach, G. A. Blair, M. A. Diaz, H. Dreiner

The Searches Working Group discussed a variety of topics relating to present and future measurements of searches at LEP 2. The individual contributions are included separately.

G. Chalmers, W. Siegel

We present a general formalism for simplifying manipulations of spin indices of massless and massive spinors and vectors in Feynman diagrams. The formalism is based on covariantly reducing the number of field components in the action in favor of chiral/self-dual fields. In this paper we concentrate on calculational simplifications involving fermions in gauge

O. V. Babourova, B. N. Frolov

The equation of perfect dilaton-spin fluid motion in the form of generalized hydrodynamic Euler-type equation in a Weyl-Cartan space is derived. The equation of motion of a test particle with spin and dilatonic charge in the Weyl-Cartan geometry background is obtained. The peculiarities of test particle motion in a Weyl-Cartan space are discussed.

Baruch Meerson, Pavel V. Sasorov

Dynamics of coarsening of a statistically homogeneous fractal cluster, created by a morphological instability of diffusion-controlled growth, is investigated theoretically. An exact mathematical setting of the problem is presented that obeys a global conservation law. A statistical mean field theory is developed that accounts for shadowing during the growth

Rajesh Gopakumar, Sanjaye Ramgoolam

We consider the scattering of zero branes off an elementary string in Matrix theory or equivalently gravitons off a longitudinally wrapped membrane. The leading supergravity result is recovered by a one-loop calculation in zero brane quantum mechanics. Simple scaling arguments are used to show that there are no further corrections at higher loops, to the lea

S. B. Popov

I discuss the nature of the compact X-ray source inside the supernova remnant RCW 103. Several models, based on the accretion onto a compact object such as a neutron star or a black hole (isolated or binary), are analyzed. I show that it is more likely that the X-ray source is an accreting neutron star than an accreting black hole. I also argue that models o

Jose A. Miranda, Michael Widom

The Saffman-Taylor viscous fingering instability occurs when a less viscous fluid displaces a more viscous one between narrowly spaced parallel plates in a Hele-Shaw cell. Experiments in radial flow geometry form fan-like patterns, in which fingers of different lengths compete, spread and split. Our weakly nonlinear analysis of the instability predicts these

A. Del Sol Mesa, C. Quesne, Yu. F. Smirnov

We study in detail the bound state spectrum of the generalized Morse potential~(GMP), which was proposed by Deng and Fan as a potential function for diatomic molecules. By connecting the corresponding Schrödinger equation with the Laplace equation on the hyperboloid and the Schrödinger equation for the Pöschl-Teller potential, we explain the exact solvabilit

Vadim Schechtman

We describe the algebra of a universal formal deformation as the zeroth cohomology of the dg Lie algebra corresponding to this deformation problem. A report at Arbeitstagung 1997 on the joint work with V.Hinich.

Phung Ho Hai

Given a Hecke symmetry $R$, one can define a matrix bialgebra $E_R$ and a matrix Hopf algebra $H_R$, which are called function rings on the matrix quantum semi-group and matrix quantum groups associated to $R$. We show that for an even Hecke symmetry, the rational representations of the corresponding quantum group are absolutely reducible and that the fusion

Arnon Dar

The Hubble Space Telescope has recently discovered thousands of gigantic comet-like objects in a ring around the central star in the nearest planetary nebula. We suggest that such circumstellar rings exist around most stars. Collisions of the relativistic debris from gamma ray bursts in dense stellar regions with such gigantic comet-like objects, which have

Oleg A. Soloviev

It is shown that the integration measure over the matrix $Y$ in the matrix representation of the Schild action can be fixed by comparing the Schild matrix model with the random lattice string model for D=0. It is further checked that the given measure is consistent with the case D=1 as well.

P. Hajicek, Berne

The subject of this paper are spherically symmetric thin shells made of barotropic ideal fluid and moving under the influence of their own gravitational field as well as that of a central black hole; the cosmological constant is assumed to be zero. The general super-Hamiltonian derived in a previous paper is rewritten for this spherically symmetric special c

R. Chitra, T. Giamarchi, P. Le Doussal

We study various dynamical properties of the weakly pinned Wigner crystal in a high magnetic field. Using a Gaussian variational method we can compute the full frequency and field dependence of the real and imaginary parts of the diagonal and Hall conductivities. The zero temperature Hall resistivity is independent of frequency and remains unaffected by diso

S. Mayburov

We argue that the account of Reference Frames quantum properties must change the standard space-time picture accepted in Quantum Mechanics. If RF is connected with some macroscopic solid object then its free quantum motion - wave packet smearing results in additional uncertainty into the measurement of test particle coordinate. It makes incorrect the use of

W. Peters, M. Post, H. Lenske, S. Leupold

We calculate the modification of a rho meson in nuclear matter through its coupling to resonance-hole states. Starting from a recently proposed model, we include all four star resonances up to 1.9 GeV. In contrast to previous works, we include not only resonances that couple to the rho in a relative p-wave, but also those that couple to an s-wave state. In a

E. G. Bessonov

In the present work foundations of the law of the energy conservation and the introduction of particles in the classical electrodynamics are discussed. We pay attention to a logic error which takes place at an interpretation of the Poynting's theorem as the law of conservation of energy. It was shown that the laws of conservation of energy and momentum o

Konstantin G. Zloshchastiev

In this paper we consider the class of exact solutions of the Schrodinger equation with the Razavi potential. By means of this we obtain some wavefunctions and mass spectra of the relativistic scalar field model with spontaneously broken symmetry near the static kink solution. Appearance of the bosons, which have two different spins, will be shown in the the

Katsushi Ito, Sung-Kil Yang

We study the Picard-Fuchs differential equations for the Seiberg-Witten period integrals in N=2 supersymmetric Yang-Mills theory. For A-D-E gauge groups we derive the Picard-Fuchs equations by using the flat coordinates in the A-D-E singularity theory. We then find that these are equivalent to the Gauss-Manin system for two-dimensional A-D-E topological Land

P. L. Shopbell, J. Bland-Hawthorn

We have obtained detailed imaging Fabry-Perot observations of the nearby galaxy M82, in order to understand the physical association between the high-velocity outflow and the starburst nucleus. The observed velocities of the emitting gas in M82 reveal a bipolar outflow of material, originating from the bright starburst regions in the galaxy's inner disk, but

R. Dum, A. Sanpera, K. -A. Suominen, M. Brewczyk

We study wave packet dynamics of a Bose condensate in a periodically shaken trap. Dichotomy, that is, dynamic splitting of the condensate, and dynamic stabilization are analyzed in analogy with similar phenomena in the domain of atoms in strong laser fields.

G. Pastore, O. Akinlade, F. Matthews, Z. Badirkhan

The optimized random phase approximation (ORPA) for classical liquids is re-examined in the framework of the generating functional approach to the integral equations. We show that the two main variants of the approximation correspond to the addition of the same correction to two different first order approximations of the homogeneous liquid free energy. Furt

W. E. Ormand

A method for making realistic estimates of the density of levels in even-even nuclei is presented making use of the Monte Carlo shell model (MCSM). The procedure follows three basic steps: (1) computation of the thermal energy with the MCSM, (2) evaluation of the partition function by integrating the thermal energy, and (3) evaluating the level density by pe

R. A. Arndt, I. I. Strakovsky, R. L. Workman

A number of recent multipole analyses from Mainz, RPI, BNL and Virginia Tech (VPI) have focused on the first resonance region. One goal common to these studies was an improved set of Delta(1232) photo-decay amplitudes. There has been considerable debate over the differing results found for A(1/2), A(3/2) and the E2/M1 ratio. We show that a much more consiste

Th. Wilbois, P. Wilhelm, H. Arenhoevel

Several methods for the treatment of pion photoproduction in the region of the Delta(1232) resonance are discussed, in particular the effective Lagrangian approach and the speed plot analysis are compared to a dynamical treatment. As a main topic, we discuss the extraction of the genuine resonance parts of the magnetic dipole and electric quadrupole multipol

H. W. Hamber, R. M Williams

Functional measures for lattice quantum gravity should agree with their continuum counterparts in the weak field, low momentum limit. After showing that the standard simplicial measure satisfies the above requirement, we prove that a class of recently proposed non-local measures for lattice gravity do not satisfy such a criterion, already to lowest order in

Julie D. Blum, Keith R. Dienes

It is well-known that the SO(32) and $E_8\times E_8$ heterotic strings can be continuously connected to each other in nine dimensions. Since the strong-coupling duals of these theories are respectively the SO(32) Type I theory and M-theory compactified on a line segment, there should be a corresponding continuous connection between the Type I string and M-th

Nemanja Kaloper, Keith A. Olive

In this article, we examine the possibility that there exist special scalar-tensor theories of gravity with completely nonsingular FRW solutions. Our investigation in fact shows that while most probes living in such a Universe never see the singularity, gravity waves always do. This is because they couple to both the metric and the scalar field, in a way whi

Isard Dunietz

Our analysis suggests that the charmless yield in B decays is enhanced over traditional estimates. The c c.bar pair produced in b to c c.bar transitions may be seen significantly as light hadrons due to non-perturbative effects. Existing data samples at Upsilon(4S) and Z^0 factories allow key measurements which are outlined.

R. Arnowitt, Pran Nath

Dark matter detection rates for supergravity models with R parity where supersymmetry is broken at a scale >~M_G are discussed. Non-universal soft breaking masses in both the Higgs and squark sectors are considered, and it is seen that these can effect rates by a factor of 10-100 when m_X <~ 65 GeV (X=lightest neutralino) but otherwise make relatively small

F. Becattini

It is shown that hadron abundances in high energy e+e-, pp and p{\bar p} collisions, calculated by assuming that particles originate in hadron gas fireballs at thermal and partial chemical equilibrium, are in very good agreement with the data. The freeze-out temperature of the hadron gas fireballs turns out to be nearly constant over a large center of mass e

R. Haeussling, F. Scheck

Every nonsingular fermion mass matrix, by an appropriate unitary transformation of right-chiral fields, is equivalent to a triangular matrix. Using the freedom in choosing bases of right-chiral fields in the minimal standard model, reduction to triangular form reduces the well-known ambiguities in reconstructing a mass matrix to trivial phase redefinitions.

P. Di Bari

We expose briefly the role of entropy in the early universe and in particular the importance of searching for new mechanisms of entropy production. We describe a mechanism that shows how entropy is produced during early annihilations and under which conditions the production is not negligible. A MeV tau neutrino provides an interesting application.

R. Gatto, M. Modugno, G. Pettini

We calculate the equation of state of the Gross-Neveu model in 2+1 dimensions at order 1/N, where N is the number of fermion species. We make use of a general formula valid for four-fermion theories, previously applied to the model in 1+1 dimensions. We consider both the discrete and continuous symmetry versions of the model. We show that the pion-like excit

F. Karsch, A. Patkos, P. Petreczky

A new perturbative scheme is proposed for the evaluation of the free energy density of field theories at finite temperature. The screened loop expansion takes into account exactly the phenomenon of screening in thermal propagators.The approach is tested in the N-component scalar field theory at 2-loop level and also at 3-loop in the large $N$ limit. The pert

M. Stratmann, W. Vogelsang

We study photoproduction reactions in a polarized ep collider mode of HERA at sqrt(s)=298 GeV. We examine the sensitivity of the cross sections and their asymmetries to the proton&#39;s polarized gluon distribution and to the completely unknown parton distributions of longitudinally polarized photons.

S. Hegyi

The H-function extension of the Negative Binomial Distribution is investigated for scaling exponents mu<0. Its analytic form is derived via a convolution property of the H-function. Applications are provided using multihadron and galaxy count data for P(n).

Bernd A. Berg

Monte Carlo (MC) simulations of many systems, in particular those with conflicting constraints, can be considerably speeded up by using multicanonical or related methods. Some of these approaches sample with a-priori unknown weight factors. After introducing the concept, I shall focus on two aspects: (i) Opinions about the optimal choice of weight factors. (

T. Carli, M. Kuhlen

Signals for processes induced by QCD instantons are searched for in HERA data on the hadronic final state in deep-inelastic scattering. The maximally allowed fraction of instanton induced events is found at 95% confidence level to be on the percent level in the kinematic domain 0.0001<x<0.01 and 5 < Q-squared < 100 GeV-squared. The most stringent limits are

ZEUS Collaboration

Using the ZEUS detector at HERA, we have searched for heavy excited states of electrons, neutrinos, and quarks in $e^+p$ collisions at a center-of-mass energy of 300~GeV. With an integrated luminosity of 9.4~pb$^{-1}$, no evidence was found for electroweak production and decay of such states. Limits on the production cross section times branching ratio and o

Friedrich W. Hehl, Uwe Muench

A four-dimensional differentiable manifold is given with an arbitrary linear connection $Γ_α^β=Γ_{iα}^βdx^i$. Megged has claimed that he can define a metric $G_{αβ}$ by means of a certain integral equation such that the connection is compatible with the metric. We point out that Megged&#39;s implicite definition of his metric $G_{αβ}$ is equivalent to the as

Jose A. Miranda, Michael Widom

Polarized ferrofluids, lipid monolayers and magnetic bubbles form domains with deformable boundaries. Stability analysis of these domains depends on a family of nontrivial integrals. We present a closed form evaluation of these integrals as a combination of Legendre functions. This result allows exact and explicit formulae for stability thresholds and growth

Victor Barzykin, Ian Affleck

We demonstrate the existence of a large Kondo screening cloud in the k-channel Kondo model using both renormalization group improved perturbation theory and the large-k limit. We study position (r) dependent spin Green&#39;s functions in both static and equal time cases. The equal-time Green&#39;s function provides a natural definition of the screening cloud

Sora Cho, Leon Balents, Matthew P. A. Fisher

The two-dimensional surface of a coupled multilayer integer quantum Hall system consists of an anisotropic chiral metal. This unusual metal is characterized by ballistic motion transverse and diffusive motion parallel (\hat{z}) to the magnetic field. Employing a network model, we calculate numerically the phase coherent two-terminal z-axis conductance and it

S. Theodorakis, E. Leontidis

We study the bound states of a Kronig Penney potential for a nonlinear one-dimensional Schroedinger equation. This potential consists of a large, but not necessarily infinite, number of equidistant delta-function wells. We show that the ground state can be highly degenerate. Under certain conditions furthermore, even the bound state that would normally be th

S. F. Fischer, P. O. J. Scherer

A new mechanism for the primary photoinduced charge separation in photosynthesis is proposed. It involves as real intermediate between the excited special pair state P* and the primary charge separated state P+HL- a trip-trip-singlet PTBLT, which consists of a triplet on the dimer P and a further triplet on the monomer BL. Both combine to a singlet. The elec

Ken Sekimoto, Shin-ichi Sasa

When the process of a system in contact with a heat bath is described by classical Langevin equation, the method of stochastic energetics [K. Sekimoto, J. Phys. Soc. Jpn. vol. 66 (1997) p.1234] enables to derive the form of Helmholtz free energy and the dissipation function of the system. We prove that the irreversible heat Q_irr and the time lapse $Delta t}

Boris Neubert, Michel Pleimling, Rolf Siems

A general concept for the derivation of symmetry-based pseudo spin Hamiltonians is described. It systematically bridges the gap between the atomistic basis and various pseudo spin models presented in literature. It thus allows the application of the multitude of analytical and numerical procedures derived for the statistical mechanics treatment of the latter

Z. Zhai, H. Srikanth, S. Sridhar, A. Erb

We report novel non-linear phenomena in the $ab$-plane microwave impedance of $YBaCu_{2}O_{7-δ}$ single crystals. The $R_s$ vs. $H_{rf}$ data are well described by the non-linear RSJ model : $\dotϕ+\sin ϕ=i_{rf}\cos ωt$. The entire crystal behaves like a single Josephson junction. The extraordinary coherence of the data suggests an intrinsic mechanism.

E. Brezin, A. Zee

We study localization and delocalization in a class of non-hermitean Hamiltonians inspired by the problem of vortex pinning in superconductors. We show how to take into account multiple scattering. We also obtain some bounds on the complex energy spectrum.

Dan Cristea, Bonnie Lynn Webber

The way in which discourse features express connections back to the previous discourse has been described in the literature in terms of adjoining at the right frontier of discourse structure. But this does not allow for discourse features that express expectations about what is to come in the subsequent discourse. After characterizing these expectations and

Victor I. Belinicher, Victor S. L&#39;vov, Itamar Procaccia

This manuscript is a draft of work in progress, meant for network distribution only. It will be updated to a formal preprint when the numerical calculations will be accomplished. In this draft we develop a consistent closure procedure for the calculation of the scaling exponents $ζ_n$ of the $n$th order correlation functions in fully developed hydrodynamic t

Arjendu K. Pattanayak, Paul Brumer

We analytically establish the role of a spectrum of Lyapunov exponents in the evolution of phase-space distributions $ρ(p,q)$. Of particular interest is $λ_2$, an exponent which quantifies the rate at which chaotically evolving distributions acquire structure at increasingly smaller scales and which is generally larger than the maximal Lyapunov exponent $λ$

Tommy Wiklind, Francoise Combes

A detailed study of the absorbing molecular clouds towards the radio source PKS1413+135, at a redshift z=0.247, is reported. Physical conditions are derived for the molecular gas in the frame work of two models: a homogeneous multicomponent model with equal filling factors, and a two-phase medium consisting of dense clumps embedded in a more diffuse componen

Martin Elvis, Fabrizio Fiore, Paolo Giommi, Paolo Padovani

We have selected quasars with X-ray colors suggestive of a low energy cut-off, from the ROSAT PSPC pointed archive. We examine the radio and optical properties of these 13 quasars. Five out of the seven quasars with good optical spectra show associated optical absorption lines, with two having high delta-v candidate systems. Two other cut-off quasars show re

Fabrizio Fiore, Martin Elvis, Paolo Giommi, Paolo Padovani

We have used the WGA catalog of ROSAT PSPC X-ray sources to study the X-ray spectrum of about 500 quasars in the redshift interval 0.1--4.1, detected with a signal to noise better than 7. We have parameterized the PSPC spectrum in terms of two `effective energy spectral indices&#39;, alpha_Soft (0.1-0.8 keV), and alpha_Hard (0.4-2.4 keV), which allows for th

B. P. Holden, A. K. Romer, R. C. Nichol, M. P. Ulmer

We have measured fluxes or flux limits for 31 of the 79 cluster candidates in the Palomar Distant Cluster Survey (PDCS) using archival ROSAT/PSPC pointed observations. Our X-ray survey reaches a flux limit of $\simeq 3 \times 10^{-14}$ erg s$^{-1}$ cm$^{-2}$ (0.4 - 2.0 keV), which corresponds to luminosities of $L_x\simeq 5 \times 10^{43}$ erg s$^{-1}$ ($H_o

Ewa L. Lokas

Using the two-point Edgeworth series up to second order we construct the weakly nonlinear conditional probability distribution function for the density field around an overdense region. This requires calculating the two-point analogues of the skewness parameter $S_{3}$. We test the dependence of the two-point skewness on distance from the peak for scale-free

I. M. George, T. J. Turner, Hagai Netzer, K. Nandra

(Abridged) We present the results from a detailed analysis of the 0.6 - 10 keV spectra of 23 ASCA observations of 18 objects. We find that in most cases the underlying continuum can be well-represented by a powerlaw with a photon index Gamma approx 2. However we find strong evidence for photoionized gas in the line-of-sight to 13/18 objects. We present detai

Kurt Roettiger, James M. Stone, Richarch F. Mushotzky

A754 is a well-observed cluster of galaxies which exhibits a variety of morphological peculiarities. These include a bar of X-ray emission that is offset significantly from the galaxy distribution, an elongated X-ray surface brightness distribution extending between two distinct peaks in the galaxy distribution, and an extremely non-isothermal and asymmetric

B. R. Ragot, J. G. Kirk

Anomalous transport processes in which the variance of the distance travelled does not necessarily increase linearly with time are modelled using the formalism of continuous time random walks. We compute particle propagators which have the required dependence on space and time and use these to find the spatial dependence of the synchrotron radiation emitted

J. G. Kirk

The theory of particle acceleration at shock fronts is briefly reviewed, with special emphasis on the production of the particles responsible for the nonthermal emission from blazars. The flat radio/IR spectra of these sources cannot be produced by diffusive acceleration at a simple nonrelativistic shock front propagating in a homogeneous medium. It can, how

The MACHO Collaboration, C. Alcock, R. A. Allsman, D. R. Alves

We report the discovery of RV Tauri stars in the Large Magellanic Cloud. In light and colour curve behaviour, the RV Tauri stars appear to be a direct extension of the type II Cepheids to longer periods. A single period- luminosity-colour relationship is seen to describe both the type II Cepheids and the RV Tauri stars in the LMC. We derive the relation: $V_

S. A. Stanford, Peter R. Eisenhardt, Mark Dickinson

We present results from an optical-IR photometric study of early-type galaxies in 19 galaxy clusters out to z=0.9. The galaxy sample is selected on the basis of morphologies determined from HST WFPC2 images, and is photometrically defined in the K-band to minimize redshift-dependent selection biases. The optical-IR colors of the early-type cluster galaxies b

Yuri G. Zarhin

Let $K$ be a field finitely generated over the field of rational numbers, $K(c)$ the extension of $K$ obtained by adjoining all roots of unity, $L$ an infinite Galois extension of $K$, $X$ an abelian variety defined over $K$. We prove that under certain conditions on $X$ and $K$ the existence of infinitely many L-rational points of finite order on $X$ implie

Martin Schmaltz, Raman Sundrum

We investigate Seiberg&#39;s N=1 field theory duality for four-dimensional supersymmetric QCD with the M-theory 5-brane. We find that the M-theory configuration for the magnetic dual theory arises via a smooth deformation of the M-theory configuration for the electric theory. The creation of Dirichlet 4-branes as Neveu-Schwarz 5-branes are passed through eac

Igor Halperin, Ariel Zhitnitsky

This paper has been withdrawn by the authors, due an incorrect treatment of the effective Lagrangian, which led to the wrong conclusion on the disappearance of physical theta dependence in gluodynamics. See hep-ph/9711398 for a correct procedure.

Edward Frenkel, Nicolai Reshetikhin

Deformed $\W$--algebra $\W_{q,t}(\g)$ associated to an arbitrary simple Lie algebra $\g$ is defined together with its free field realizations and the screening operators. Explicit formulas are given for generators of $\W_{q,t}(\g)$ when $\g$ is of classical type. These formulas exhibit a deep connection between $\W_{q,t}(\g)$ and the analytic Bethe Ansatz in

Daniel E. Holz, Robert M. Wald

We present a new approach to calculating the statistical distributions for magnification, shear, and rotation of images of cosmological sources due to gravitational lensing. In this approach one specifies an underlying Robertson-Walker cosmological model together with relevant information on the clumping of matter on scales much smaller than the Hubble radiu

C. P. Constantinidis, F. P. Devecchi

The 2-dimensional version of the Schwarz and Sen duality model (Tseytlin model) is analyzed at the classical and quantum levels. The solutions are obtained after removing the gauge dependent sector using the Dirac method. The Poincarè invariance is verified at both levels. An extension with global supersymmetry is also proposed.

V. S. Podolsky, Lev I. Deych, A. A. Lisyansky

We consider the dynamics of an ionic crystal with a single impurity in the vicinity of the polariton resonance. We show that if the polariton spectrum of the host crystal allows for a gap between polariton branches, the defect gives rise to a novel kind of local states with frequencies within the gap. Despite the atomic size of the impurity we find that new

Adam Szczepaniak, Anatoly Radyushkin, Chueng-Ryong Ji

We examine the role of O(α_s) perturbative corrections to the pion elastic form factor F_π(Q^2). We express the quark current three-point function in terms of light cone variables and use Borel transformation to simultaneously model the Feynman mechanism contribution determined by the soft part of the pion light cone wave function and the hard term involving

O. V. Babourova, B. N. Frolov

The variational theory of the perfect fluid with intrinsic spin and dilatonic charge (dilaton-spin fluid) is developed. The spin tensor obeys the classical Frenkel condition. The Lagrangian density of such fluid is stated, and the equations of motion of the fluid, the Weyssenhoff-type evolution equation of the spin tensor and the conservation law of the dila

John C. Baez, Stephen Sawin

We extend the theory of diffeomorphism-invariant spin network states from the real-analytic category to the smooth category. Suppose that G is a compact connected semisimple Lie group and P -> M is a smooth principal G-bundle. A `cylinder function&#39; on the space of smooth connections on P is a continuous complex function of the holonomies along finitely m

Charles D. Bailyn, Raj K. Jain, Paolo Coppi, Jerome A. Orosz

We examine the distribution of masses of black holes in transient low mass X-ray binary systems. A Bayesian analysis suggests that it is probable that six of the seven systems with measured mass functions have black hole masses clustered near seven solar masses. There appears to be a significant gap between the masses of these systems and those of the observ

Leovigildo Alonso, Ana Jeremias, Joseph Lipman

We give several related versions of global Grothendieck Duality for unbounded complexes on noetherian formal schemes. The proofs, based on a non-trivial adaptation of Deligne's method for the special case of ordinary schemes, are reasonably self-contained, modulo the Special Adjoint Functor Theorem. An alternative approach, inspired by Neeman and based on re

Enzo Marinari, Giorgio Parisi, Davide Rossetti

We study the dynamical behavior of the Sherrington Kirkpatrick model. Thanks to the APE supercomputer we are able to analyze large lattice volumes, and to investigate the low $T$ region. We present a determination of the remnant magnetization and of its time decay exponent, of the energy time decay exponent, and we discuss aging phenomena in the model.

Dzero Collaboration, B. Abbott

We search for inclusive high $E_T$ diphoton events with large missing transverse energy in $p\bar{p}$ collisions at $\sqrt{s}$=1.8 TeV. Such events are expected from pair production of charginos and neutralinos within the framework of the minimal supersymmetric standard model with a light gravitino. No excess of events is observed. In that model, and assumin

Andrej Vilfan, Erwin Frey, Franz Schwabl

We discuss the force-velocity relations obtained in a two-state crossbridge model for molecular motors. They can be calculated analytically in two limiting cases: for a large number and for one pair of motors. The effect of the strain-dependent detachment rate on the motor characteristics is studied. It can lead to linear, myosin-like, kinesin-like and anoma

Adel Khoudeir, Yoan Parra

The $SL(2,R)$ duality symmetric action for the Born-Infeld theory in terms of two potentials, coupled with non-trivial backgroud fields in four dimensions is established. This construction is carried out in detail by analysing the hamiltonian structure of the Born-Infeld theory. The equivalence with the usual Born-Infeld theory is shown.

M. Requardt

Continuing previous work we develop a certain piece of functional analysis on general graphs and use it to create what Connes calls a &#39;spectral triple&#39;, i.e. a Hilbert space structure, a representation of a certain (function) algebra and a socalled &#39;Dirac operator&#39;, encoding part of the geometric/algebraic properties of the graph. We derive i

M. Peter, Y. Sumino

We calculate final-state interaction corrections to the energy-angular distribution of l^+ in semi-leptonic top quark decay, where the parent top quark is produced via e^+e^- -> t\bar{t} near threshold. These are the corrections due to gluon exchange between t and \bar{b} (\bar{t} and b) and between b and \bar{b}. Combining with previously known other correc

M. Hayakawa, T. Kinoshita

The pseudoscalar pole contribution is the dominant source of the $ {\cal O}(α^3) $ hadronic light-by-light scattering effect in muon $g - 2$. We have examined this contribution taking account of the off-shell structure of the pseudoscalar-photon-photon anomaly vertex deduced from available experimental data. Our work leads to an improved estimate, $ -79.2 (1