October 1999 arXiv papers — page 17

Joachim Krug, Martin Rost

Unstable homoepitaxy on rough substrates is treated within a linear continuum theory. The time dependence of the surface width $W(t)$ is governed by three length scales: The characteristic scale $l_0$ of the substrate roughness, the terrace size $l_D$ and the Ehrlich-Schwoebel length $l_{ES}$. If $l_{ES} \ll l_D$ (weak step edge barriers) and $l_0 \ll l_m \s

D. Queloz, M. Mayor, L. Weber, A. Blecha

A 4MJ planet with a 15.8day orbital period has been detected from very precise radial velocity measurements with the CORALIE echelle spectrograph. A second remote and more massive companion has also been detected. All the planetary companions so far detected in orbit closer than 0.08 AU have a parent star with a statistically higher metal content compared to

Wayne Hu, P. J. E. Peebles

This model assumes the baryons, radiation, three families of massless neutrinos, and cold dark matter were mutually thermalized before the baryon number was fixed, primeval curvature fluctuations were subdominant, and homogeneity was broken by scale-invariant fluctuations in a new dark matter component that behaves like a relativistic ideal fluid. The fluid

Romeel Davé, Lars Hernquist, Neal Katz, David H. Weinberg

We determine the evolution from $z=3\to 0$ of the galaxy and mass correlation functions and bias factor in a $50h^{-1}$Mpc $Λ$CDM hydrodynamic simulation with $10h^{-1}$kpc resolution. The mass correlation function grows with time, but the galaxy correlation function shows little evolution and is well described by a power law. At early times, galaxies are bi

Romeel Davé, Jeffrey P. Gardner, Lars Hernquist, Neal Katz

What type of objects are being detected as $z\sim 3$ "Lyman break galaxies"? Are they predominantly the most massive galaxies at that epoch, or are many of them smaller galaxies undergoing a short-lived burst of merger-induced star formation? We attempt to address this question using high-resolution cosmological hydrodynamic simulations including sta

J. J. Dalcanton, R. A. Bernstein

We present first results of a program to study the dynamics of undisturbed bulgeless, low surface density disk galaxies in order to probe the underlying structure of dark matter halos. High resolution H-alpha rotation curves are combined with optical and infrared imaging to place strong limits on the halo profiles. We find noticable variation in the shapes o

I. M. George, T. J. Turner, T. Yaqoob, H. Netzer

We present the result of 27 ASCA observations of 26 radio-quiet quasars (RQQs) from the PG survey. All the RQQs were detected except 2 BALQSOs. We find the variability characteristics of the sources to be consistent with Seyf-1s. A powerlaw offers an acceptable description of the time-averaged spectra in the 2-10 keV (RQQ-frame) band for all but 1 dataset. T

T. J. Turner, G. C. Perola, F. Fiore, G. Matt

This paper presents a BeppoSAX observation of NGC 7582 made during 1998 November and an optical spectrum taken in 1998 October. The new X-ray data reveal a previously unknown hard X-ray component in NGC 7582, peaking close to 20 keV. Rapid variability is observed with correlated changes in the 5-10 and 13-60 keV bands indicating that a single continuum compo

Edward F. Brown

A neutron star in a long-lived, low-mass binary can easily accrete enough matter to replace its entire crust. Previous authors noted that an accreted crust, being formed from the burning of accreted hydrogen and helium, allows a series of non-equilibrium reactions, at densities >6e11 g/cc, which release a substantial amount of heat (1 MeV per accreted nucleo

M. V. Naik, S. L. D'Costa, S. K. Ghosh, B. Mookerjea

The observational and operational efficiency of the TIFR 1 meter balloon borne far infrared telescope has been improved by incorporating a multielement solid state optical photometer (SSOP) at the Cassegrain focus of the telescope. The SSOP is based on a 1-D linear photo diode array (PDA). The online and offline processing schemes of the PDA signals which ha

Tammy A. Smecker-Hane, Georgi I. Mandushev, James E. Hesser, Peter B. Stetson

We report on the chemical abundances of stars in the Carina dwarf spheroidal galaxy (dSph) derived from low-resolution spectra. We have determined values of [Fe/H] for 52 stars from the reduced equivalent width of the Ca II infrared triplet lines. The Carina dSph has a mean metallicity of [Fe/H] = -1.99 +/- 0.08 and an intrinsic metallicity dispersion 0.25 d

Tammy Smecker-Hane, Andrew McWilliam

The dwarf spheroidal galaxies (dSphs) in the Local Group are excellent systems on which we can test theories of galaxy formation and evolution. Color-magnitude diagrams (CMDs) containing many thousands of stars from the asymptotic giant branch to well below the oldest main-sequence turnoff are being used to infer their star-formation histories, and surprisin

Patricia C. Hanlan, Joel N. Bregman

The slow inward flow of the hot gas in elliptical galaxy cooling flows is nearly impossible to detect directly due to instrumental limitations. However, in rotating galaxies, if the inflowing gas conserves angular momentum, it will eventually form a disk. The X-ray signature of this phenomenon is a flattening of the X-ray isophotes in the inner 1-10 kpc regi

P. Cassaro, C. Stanghellini, M. Bondi, D. Dallacasa

We have observed 28 sources selected from the 1Jy sample of BL Lac objects (Stickel et al. 1991) with the Very Large Array (VLA) in A, B and D configurations at 1.36, 1.66 and 4.85 GHz, and/or with the Westerbork Synthesis Radio Telescope (WSRT) at 1.40 GHz. In this paper we present high sensitivity images at arcsecond resolution of the 18 objects showing ex

Christian Hettlage, Karl Mannheim, John G. Learned

Cosmic ray interactions in the solar atmosphere yield a flux of electron and muon neutrinos with energies greater than 10 GeV. We discuss the influence of neutrino oscillations on the event rates in water-based Cerenkov detectors due to this neutrino flux and comment on the possibility of detecting the sun as a high energy neutrino source.

J. Kaluzny, I. Thompson, W. Krzeminski, W. Pych

We present the results of a photometric survey for variable stars in the nearby globular cluster M5. A 14.8x22.8 arcmin^2 field centered on the cluster was monitored for a total of 37 hours with a CCD camera mounted on the 1.0-m Swope telescope. Five new variables were identified: four blue stragglers which are SX Phe pulsating variables, and an eclipsing bi

Felix Ryde

A review on the spectral and temporal properties of gamma-ray bursts is given. Special attention is paid to the spectral evolution of their continuum emission and its connection to the time evolution of the intensity. Efforts on systematizing these observations as well as the effects due the limitations of the current detectors on the observed sample are dis

Lawrence Rudnick

I introduce a straightforward technique for the filtering of extended astronomical images into components of different spatial scales. For a positive original image, each component is positive definite, and the sum of all components equals the original image. In this way, the components are each individually suitable for flux measurements and broadband spect

Lawrence Rudnick

I present a brief overview of observational, modeling and theoretical issues related to ageing calculations based on spectral steepening. These include problems such as inhomogeneous magnetic fields, diffusion of relativistic particles, confusion from multiple particle populations and particle acceleration. Although some of the effects are only of order unit

L. Gregorini, I. Prandoni

The change in the slope of the radio source counts suggests the emergence of a new population of radio galaxies at mJy and sub-mJy levels. Our understanding of such faint radio sources has advanced over the last decade through increasingly sensitive radio surveys and follow-up works at optical wavelength. The sub-mJy population seems to include both star for

Gabriela Canalizo, Alan Stockton, M. S. Brotherton, Wil van Breugel

UN J1025-0040 is a quasar at z = 0.6344 that shows an extremely bright post starburst population of age ~ 400 Myr (Brotherton et al. 1999). Images of UN J1025-0040 show a nearly stellar object 4.2 arcseconds SSW of the quasar. We present imaging and spectroscopy that confirm that this object is a companion galaxy at redshift z = 0.6341. We estimate an age of

Cheongho Han

To improve photometric precision by removing blending effect, a newly developed technique of difference image analysis (DIA) is adopted by several gravitational microlensing experiment groups. However, the principal problem of the DIA method is that, by its nature, it has difficulties in measuring the baseline flux $F_0$ of a source star, causing degeneracy

V. N. Lukash

In these lectures we dwell upon the cosmological corner-stones of the Very Early Universe (VEU) theory: Parametric Amplification Effect (PAE) responsible for the generation of Primordial Cosmological Perturbations (PCPs), Chaotic and Stochastic Inflation, Principal Tests of VEU, and others.

Hector Aceves

We present a study of the dynamics of triplets of galaxies. In particular we focus on properties that are directly comparable with observations: e.g., velocity dispersion, mean harmonic radius, and virial mass. We find, for example, that the median velocity dispersion of our simulations is smaller (<50 km/s) than the observed value (~100 km/s). A possible so

Fran De Aquino

This is a set of 25 articles, developed starting from the Relativistic Theory of Quantum Gravity (first article). Together they form the Theory of Everything.

Haim Diamant, David Andelman

A theory is presented for the binding of small molecules such as surfactants to semiflexible polymers. The persistence length is assumed to be large compared to the monomer size but much smaller than the total chain length. Such polymers (e.g. DNA) represent an intermediate case between flexible polymers and stiff, rod-like ones, whose association with small

Piotr Popowski

I demonstrate that the two unexpected results in the local Universe: 1) anomalous intrinsic (V-I)_0 colors of the clump giants and RR Lyrae stars in the Galactic center, and 2) very short distances to the Magellanic Clouds (LMC, SMC) as inferred from clump giants, are connected with each other. The (V-I)_0 anomaly is partially resolved by using the photometr

C. Song, Z. Cao, B. R. Dawson, B. E. Fick

We use the CORSIKA air shower simulation program to review the method for assigning energies to ultra-high energy (UHE) cosmic rays viewed with the air fluorescence technique. This technique uses the atmosphere as a calorimeter, and we determine the corrections that must be made to the calorimetric energy to yield the primary cosmic ray energy.

Jamal Jalilian-Marian, Sangyong Jeon, Raju Venugopalan, Jens Wirstam

The one loop effective action in quantum field theory can be expressed as a quantum mechanical path integral over world lines, with internal symmetries represented by Grassmanian variables. In this paper, we develop a real time, many body, world line formalism for the one loop effective action. In particular, we study hot QCD and obtain the classical transpo

Andre de Gouvea, Alexander Friedland, Hitoshi Murayama

We determine the sensitivity of the KamLAND and Borexino experiments to the neutrino regeneration effect in the Earth as a function of Delta m^2 and theta, using realistic numbers for the signal and background rates. We compare the results obtained with the chi^2 method with those obtained from the conventional day-night asymmetry analysis. We also investiga

Roberto Mignani, Roberto Scipioni

We present an approach to generalised fermionic statistics which relates the existence of a generalised statistical behaviour to non-invariant ground states. Considering the thermal average of an operatorial generalization of the Heisenberg algebra, we get an occupation number which depends on the degree of mixing between symmetric and antisymmetric sectors

G. Waysand, D. Bloyet, J. P. Bongiraud, J. I. Collar

In compliance with international agreements on nuclear weapons limitation, the French ground-based nuclear arsenal has been decommissioned in its totality. One of its former underground missile control centers, located in Rustrel, 60 km east of Avignon (Provence) has been converted into the ``Laboratoire Souterrain à Bas Bruit de Rustrel-Pays d&#39;Apt&#39;&

JM Figueroa-O&#39;Farrill

Certain supergravity solutions (including domain walls and the magnetic fivebrane) have recently been generalised by Brecher and Perry by relaxing the condition that the brane worldvolume be flat. In this way they obtain examples in which the brane worldvolume is a static spacetime admitting parallel spinors. In this note we simply point out that the restric

Davide Lazzati, Gabriele Ghisellini, Annalisa Celotti, Martin J. Rees

It is proposed that the gamma-ray photons that characterize the prompt emission of Gamma-Ray Bursts are produced through the Compton drag process, caused by the interaction of a relativistic fireball with a very dense soft photon bath. If gamma-ray bursts are indeed associated with Supernovae, then the exploding star can provide enough soft photons for radia

Remo Garattini

A simple model of spacetime foam, made by N wormholes in a semiclassical approximation, is taken under examination. The Casimir-like energy of the quantum fluctuation of such a model and its probability of being realized are computed. Implications on the Bekenstein-Hawking entropy and the cosmological constant are considered.

I. Caprini, L. Micu, C. Bourrely

We bring some clarifications and improvements to the method of dispersion relations in the external masses variables, that we proposed recently for investigating the final state interactions in the B nonleptonic decays. We first present arguments for the existence of an additional term in the dispersion representation, which arises from an equal-time commuta

S. W. Allen, A. C. Fabian, R. M. Johnstone, K. A. Arnaud

We present a detailed analysis of the X-ray properties of the cooling flows in a sample of nearby, X-ray bright clusters of galaxies using high-quality ASCA spectra and ROSAT X-ray images. We demonstrate the need for multiphase models to consistently explain the spectral and imaging X-ray data for the clusters. The mass deposition rates of the cooling flows,

Ya. M. Blanter, M. Buttiker

Theoretical and experimental work concerned with dynamic fluctuations has developed into a very active and fascinating subfield of mesoscopic physics. We present a review of this development focusing on shot noise in small electric conductors. Shot noise is a consequence of the quantization of charge. It can be used to obtain information on a system which is

Aseshkrishna Datta, Biswarup Mukhopadhyaya, Francesco Vissani

We show that an R-parity violating supersymmetric scenario which can account for the atmospheric nu(mu) deficit has testable signals at the Fermilab Tevatron with upgraded energy and luminosity. The explanation of neutrino masses and maximal nu(mu)-nu(tau) oscillation in terms of bilinear R-violating terms in the superpotential associates comparable numbers

Hai-Yang Cheng, Kwei-Chou Yang

Implications of recent CLEO measurements of hadronic charmless B decays are discussed. (i) Employing the Bauer-Stech-Wirbel (BSW) model for form factors as a benchmark, the $B\toπ^+π^-$ data indicate that the form factor $F_0^{Bπ}(0)$ is smaller than that predicted by the BSW model, whereas the data of $B\toωπ, K^*η$ imply that the form factors $A_0^{Bω}(0),

I. Anderson, M. Fels, C. Torre

We present a generalization of Lie&#39;s method for finding the group invariant solutions to a system of partial differential equations. Our generalization relaxes the standard transversality assumption and encompasses the common situation where the reduced differential equations for the group invariant solutions involve both fewer dependent and independent

Nipun Vats, Terry Rudolph, Sajeev John

The single photon occupation of a localized field mode within an engineered network of defects in a photonic band-gap (PBG) material is proposed as a unit of quantum information (qubit). Qubit operations are mediated by optically-excited atoms interacting with these localized states of light as the atoms traverse the connected void network of the PBG structu

Marek Zukowski, Dagomir Kaszlikowski

A sequence of Bell inequalities for N-particle systems, which involve three settings of each of the local measuring apparatuses, is derived. For Greenberger-Horne-Zeilinger states, quantum mechanics violates these inequalities by factors exponentially growing with N. The threshold visibilities of the multiparticle sinusoidal interference fringes, for which l

Qiong-gui Lin

The scattering of relativistic Dirac particles by a Coulomb field $\pm Ze^2/r$ in two dimensions is studied and the scattering amplitude is obtained as a partial wave series. For small $Z$ the series can be summed up approximately to give a closed form. The result, though being aproximate, exhibites some nonperturbative feature and cannot be obtained from pe

Renat A. Sultanov, Sadhan K. Adhikari

Three-body charge transfer reactions with Coulomb interaction in the final state are considered in the framework of coordinate-space integro-differential Faddeev-Hahn-type equations within two- and six-state close coupling approximations. The method is employed to study direct muon transfer in low-energy collisions of the muonic hydrogen H$_μ$ by helium (He$

Renat A. Sultanov, Sadhan K. Adhikari

Low-energy muon-transfer cross sections and rates in collisions of muonic atoms with hydrogen isotopes are calculated using a six-state close-coupling approximation to coordinate-space Faddeev-Hahn-type equations. In the muonic case satisfactory results are obtained for all hydrogen isotopes and the experimentaly observed strong isotopic dependence of transf

J. C. R. Bloch, M. A. Ivanov, T. Mizutani, C. D. Roberts

We explore the Delta-I= 1/2 rule and epsilon&#39;/epsilon in K -> pi pi transitions using a Dyson-Schwinger equation model. Exploiting the feature that QCD penguin operators direct K^0_S transitions through 0^{++} intermediate states, we find an explanation of the enhancement of I=0 K -> pi pi transitions in the contribution of a light sigma-meson. This mech

Ye. S. Golubeva, W. Cassing, L. A. Kondratyuk, A. Sibirtsev

We explore the possibility to measure the elastic and inelastic $ωN$ cross section in $p{+}d{\to}d{+}ω{+}p_{sp}$ and $p{+}A$ reactions. Our studies indicate that the elastic scattering cross sections can be determined for $ω$ momenta above 1 GeV/c in $p{+}d$ reactions by gating on high proton spectator momenta whereas the $ωN$ absorption cross section down t

R. Shyam, I. J. Thompson

The calculated rate of events in some of the existing solar neutrino detectors is directly proportional to the rate of the $^7$Be($p,γ)^8$B reaction measured in the laboratory at low energies. However, the low-energy cross sections of this reaction are quite uncertain as various measurements differ from each other by 30-40 %. The Coulomb dissociation process

DISTO collaboration, F. Balestra, Y. Bedfer, R. Bertini

The total cross section of the reaction $pp\to ppK^+K^-$ has been determined for proton--proton reactions with $p_{beam}=3.67 GeV/c$. This represents the first cross section measurement of the $pp \to ppK^-K^+$ channel near threshold, and is equivalent to the inclusive $pp\to ppK^-X$ cross section at this beam momentum. The cross section determined at this b

A. Schiller, L. Bergholt, M. Guttormsen, E. Melby

We present a new iterative procedure to extract the level density and the gamma strength function from primary gamma spectra for energies close up to the neutron binding energy. The procedure is tested on simulated spectra and on data from the Yb-173(He-3,alpha)Yb-172 reaction.

P. Busch

In the statistical description of dynamical systems, an indication of the irreversibility of a given state change is given geometrically by means of a (pre-)ordering of state pairs. Reversible state changes of classical and quantum systems are shown to be represented by isometric state transformations. An operational distinction between reversible and irreve

A. Iliev, D. Markushevich

The Abel-Jacobi maps of the families of elliptic quintics and rational quartics lying on a smooth cubic threefold are studied. It is proved that their generic fiber is the 5-dimensional projective space for quintics, and a smooth 3-dimensional variety birational to the cubic itself for quartics. The paper is a continuation of the recent work of Markushevich-

Miguel Abreu, Dusa McDuff

Let $M$ be either $S^2\times S^2$ or the one point blow-up $\cp# \bcp$ of $\cp$. In both cases $M$ carries a family of symplectic forms $\om_\la$, where $\la > -1$ determines the cohomology class $[\om_\la]$. This paper calculates the rational (co)homology of the group $G_\la$ of symplectomorphisms of $(M,\om_\la)$ as well as the rational homotopy type of it

Laurent Bartholdi

I answer a question from the 1993 International Mathematical Olympiads by constructing an equivalent algebraic problem, and unearth a surprising behaviour of some polynomials over the two-element field.

Walter D. Neumann, Paul Norbury

We give a topological model for a polynomial map from $\C^n$ to $\C$ in the neighborhood of a fiber with isolated singularities. This is motivated out of the ``unfolding of links&#39;&#39; described earlier by the first author and Lee Rudolph. The topological model gives a useful encoding of the local and global monodromy for the map. The new ingredients ---

Karim Benakli, Yaron Oz

We consider heterotic string compactifications to four dimensions when instantons shrink to zero size. If the standard model gauge group originates from the new gauge symmetry associated with the small instantons singularity, then the weakly or strongly coupled heterotic string scales can be taken to be arbitrarily low. The SO(32) and E_8\times E_8 gauge gro

J. Sonnenschein

We present a theorem that determines the value of the Wilson loop associated with a Nambu-Goto action which generalizes the action of the $AdS_5\times S_5$ model. In particular we derive sufficient conditions for confining behavior. We then apply this theorem to various string models. We go beyond the classical string picture by incorporating quadratic quant

Andrey Dubin

I propose a class of D\geq{2} lattice SU(N) gauge theories dual to certain vector models endowed with the local [U(N)]^{D} conjugation-invariance and Z_{N} gauge symmetry. In the latter models, both the partitition function and Wilson loop observables depend nontrivially only on the eigenvalues of the link-variables. Therefore, the vector-model facilitates a

J. Karkowski, Z. Swierczynski

The excitations of the vortex in Abelian Higgs model with small ratio of vector and Higgs particle masses are considered. Three main modes encountered in numerical computations are described in detail. They are also compared to analytic results obtained recently by Arodz and Hadasz.

Jan Rafelski, Jean Letessier

We review the current status of strangeness as signature of the formation and dissociation of the deconfined QGP at the SPS energy scale, and present the status of our considerations for RHIC energies. By analyzing, within the framework of a Fermi statistical model, the hadron abundance and spectra, the properties of a disintegrating, hadron evaporating, dec

G. Tavares-Velasco, J. J Toscano

We discuss the implications on light by light scattering of two kind of exotic particles: doubly charged scalar bosons and doubly charged fermions; the virtual effects of a nonstandard singly charged gauge boson are also examined. These particles, if their masses lie in the range 0.1--1.0 TeV, will have a clear signature in the future linear colliders. The p

Benoit Vanderheyden, A. D. Jackson

We discuss random matrix models for the spontaneous breaking of both chiral and color symmetries at zero chemical potential and finite temperature. Exploring different Lorentz and gauge symmetric color structures of the random matrix interactions, we find that spontaneous chiral symmetry breaking is always thermodynamically preferred over diquark condensatio

Peter Kroll

The soft physics approach to form factors and Compton scattering at moderately large momentum transfer is reviewed. It will be argued that in that approach the Compton cross section is given by the Klein-Nishina cross section multiplied by a factor describing the structure of the proton in terms of two new form factors. These form factors as well as the ordi

Y. Kato

In Supersymmetry with large $\tanβ$ values, the lighter stau ($\tildeτ_{1}$) may be lighter than the lightest chargino ($\tildeχ^{\pm}_{1}$). The decay $\tildeχ^{\pm}_{1} \to \tildeτ^{\pm}_{1} ν_τ$, followed by $\tildeτ^{\pm}_{1} \to \tildeχ^{0}_{1} τ$, alters a phenomenology of the chargino production. We study the chargino pair production at future $e^{+}e

Davison E. Soper

Calculations of observables in quantum chromodynamics are typically performed using a method that combines numerical integrations over the momenta of final state particles with analytical integrations over the momenta of virtual particles. I describe the most important steps of a method for performing all of the integrations numerically.

G. Moortgat-Pick, S. Hesselbach, F. Franke, H. Fraas

We study polarization and spin correlation effects in the MSSM and in extended supersymmetric models at an e^+e^- linear collider with polarized beams. The production of light neutralinos e^+ e^- --> \tildeχ^0_1 \tildeχ^0_2 and the subsequent decay \tildeχ^0_2 --> \tildeχ^0_1 e^+ e^- including full spin correlations is compared in three supersymmetric models

A. Abada, D. Becirevic, Ph. Boucaud, J. P. Leroy

We present preliminary results for heavy to light transitions of pseudoscalar mesons, induced by the vector and tensor operators. This lattice study is performed in quenched approximation, by using the nonperturbatively improved Wilson action and operators. We also update the values of the heavy-light meson decay constants.

L3 Collaboration

A search for excited leptons, e*, mu*, tau*, nu_e*, nu_mu*, and nu_tau* was performed with the L3 detector at LEP using data collected at a centre-of-mass energy of 189 GeV, corresponding to an integrated luminosity of 176 pb^{-1}. No evidence of their production is observed. From the searches for pair produced excited leptons, lower mass limits are set clos

L3 Collaboration

Searches for scalar top and scalar bottom quarks, as well as for mass-degenerate scalar quarks of the first two families are performed at 189 GeV centre-of-mass energy with the L3 detector at LEP. No signals are observed. Model-independent limits on the scalar top production cross sections are determined for the decay modes t1~ -> c chi_1^0 and t1~ -> b l nu

M. Caccia, R. Campagnolo, C. Meroni, W. Kucewicz

The physics goals at the future e+e- linear collider require high performance vertexing and impact parameter resolution. Two possible technologies for the vertex detector of an experimental apparatus are outlined in the paper: an evolution of the Hybrid Pixel Sensors already used in high energy physics experiments and a new detector concept based on the mono

Peter J. Bussey

The past year has seen a number of important developments in hard photoproduction physics at the HERA Collider. These are surveyed.

Masahiro Kuze

The latest status of searches at HERA for physics beyond the Standard Model is summarized on behalf of the H1 and ZEUS collaborations. Emphasis is put on production of resonant particles accessible within the HERA center-of-mass energy, such as leptoquarks, squarks in R-parity-violating supersymmetry or excited fermions. Most of the results presented here ar

J. W. van Holten

The existence of Killing-Yano tensors on space-times can be probed by spinning particles. Specifically, Dirac particles possess new fermionic constants of motion corresponding to non-standard supersymmetries on the particle worldline. A geometrical duality connects space-times with Killing-Yano structure, but without torsion, to other space-times with Killin

H. F. Dowker, R. S. Garcia, S. Surya

Studies in 1+1 dimensions suggest that causally discontinuous topology changing spacetimes are suppressed in quantum gravity. Borde and Sorkin have conjectured that causal discontinuities are associated precisely with index 1 or n-1 Morse points in topology changing spacetimes built from Morse functions. We establish a weaker form of this conjecture. Namely,

A. V. Izyumov, B. D. Simons

We develop a general variational approach to study the statistical properties of the tail states of a wide class of non-Hermitian operators. The utility of the method, which is a refinement of the instanton approach introduced by Zittartz and Langer, is illustrated in detail by reference to the problem of a quantum particle propagating in an imaginary scalar

G. Baskaran

Members of the high Tc cuprate family (with defect free $CuO_2$ planes) are suggested to have an `{\em Intrinsic single layer superconducting} Tc&#39;, larger than the experimentally observed Tc, at a given hole concentration. This difference occurs to varying degrees among the different members, due to an anomalous response of the d-wave superconducting sta

Gary S. Grest, Mathias Puetz, Kurt Kremer, Ralf Everaers

The non-linear stress-strain relation for crosslinked polymer networks is studied using molecular dynamics simulations. Previously we demonstrated the importance of trapped entanglements in determining the elastic and relaxational properties of networks. Here we present new results for the stress versus strain for both dry and swollen networks. Models which

T. Hikihara, M. Kaburagi, H. Kawamura, T. Tonegawa

The ground-state phase diagram of frustrated S=1 XXZ spin chains with the competing nearest- and next-nearest-neighbor antiferromagnetic couplings is studied using the infinite-system density-matrix renormalization-group method. We find six different phases, namely, the Haldane, gapped chiral, gapless chiral, double Haldane, Néel, and double Néel (uudd) phas

Th. Oestreich, L. J. Sham

We present an analytical and numerical study of the coherent exciton polarization including exciton-exciton correlation. The time evolution after excitation with ultrashort optical pulses can be divided into a slowly varying polarization component and novel ultrafast collective modes. The frequency and damping of the collective modes are determined by the hi

Richard P. Sear

Hard spheres with an attraction of range a tenth to a hundredth of the sphere diameter are constrained to remain fluid even at densities when monodisperse particles at equilibrium would have crystallised, in order to compare with experimental systems which remain fluid. They are found to have a fluid-fluid transition at high density. As the range of the attr

Takuya Okabe

We evaluate vertex corrections to $T_c$ on the basis of the antiferromagnetic spin-fluctuation model of the high-$T_c$ superconductivity. It is found that the corrections are attractive in the $d_{x^2-y^2}$ channel, and they become appreciable as we go through an intermediate-coupling regime of $T_c\simeq 100$K, the maximum $T_c$ attainable in the one-loop É

Hongsuk Yi, N. H. Hur, Jaejun Yu

The magnetic susceptibility and spin-spin correlation of the double-exchange model for doped manganites are investigated through the Monte Carlo calculations on the three-dimensional lattice model. Deviations of the susceptibility from the Curie-Weiss behavior above the ferromagnetic ordering temperature $T_c$ seem to indicate a formation of local ferromagne

Hongsuk Yi, Jaejun Yu, Sung-Ik Lee

From a Monte Carlo study of the ferromagnetic Kondo lattice model for doped manganites, including the antiferromagnetic superexchange interaction ($J_{AF}$), we found that the ferromagnetic ordering was suppressed as $J_{AF}$ increased. The ferromagnetic transition temperature $T_c$, as obtained from a mean field fit to the calculated susceptibilities, was f

Abhik Basu

We study the effects of homogenous and isotropic initial conditions on decaying Magnetohydrodynamics (MHD). We show that for an initial distribution of velocity and magnetic field fluctuations, appropriately defined structure functions decay as power law in time. We also show that for a suitable choice of initial cross-correlations between velocity and magne

M. R. de Oliveira, E. Bica, H. Dottori

We performed numerical simulations of star cluster encounters with Hernquist&#39;s TREECODE in a CRAY YMP-2E computer. We used different initial conditions (relative positions and velocities, cluster sizes, masses and concentration degrees) with total number of particles per simulation ranging from 4608 to 20480. Long term interaction stages (up to 1 Gyr) wh

Danielle Alloin, Richard Barvainis, Stephane Guilloteau

The z=2.39 radio galaxy 53W002 lies in a cluster of Ly-alpha emission line objects and may itself be undergoing a major burst of star formation. CO(3--2) emission, at 102 GHz, was detected from 53W002 by Scoville et al. (1997a), who also reported a possible 30 kpc extension and velocity gradient suggesting a rotating gaseous disk. In this paper we present ne

Chris Mihos

Measurements of the kinematics of merging galaxies are often used to derive dynamical masses, study evolution onto the fundamental plane, or probe relaxation processes. These measurements are often compromised to some degree by strong non-equilibrium motions in the merging galaxies. This talk focuses on the evolution of the kinematics of merging galaxies, an

M. Guainazzi, S. Molendi, P. Vignati, G. Matt

An-energy dependent variation of the X-ray emission from the archetypical &#34;Compton-thick&#39;&#39; Seyfert 2 galaxy NGC1068 has been observed between two BeppoSAX observations, performed one year apart. This variation (at the 2.6 sigma level) is highest in the 3--10 keV band and declines towards lower and higher energies. The most straightforward explana

H. -W. Rix, E. Falco, C. Impey, C. Kochanek

We present H-band observations of gravitationally lensed QSO host galaxies obtained with NICMOS on HST as part of the CfA-Arizona-Gravitational-Lens-Survey (CASTLES). The detections are greatly facilitated by the lensing magnification in these systems; we find that most hosts of radio-quiet QSOs (RQQ) at z~2 are of modest luminosity (L<L_*). They are 2-5 tim

L. V. E. Koopmans, A. G. de Bruyn

We present the first unambiguous case of external variability of an extra-galactic radio source, the CLASS gravitational lens B1600+434, consisting of two images lensed by an edge-on disk galaxy. The VLA 8.5-GHz difference light curve of the lens images shows external variability at the 14.6-sigma confidence level. Although the current single-frequency VLA o

A. Coc, M. G. Porquet, F. Nowacki

We study here the onset of thermal equilibrium affecting the lifetimes of 26Al and 34Cl nuclei within a hot astrophysical photon gas. The 26Al isotope is of prime interest for gamma ray astronomy with the observation of its delayed (t_1\2=0.74 My) 1.809MeV gamma-ray line. Its nucleosynthesis is complicated by the presence of a short lived (t_1\2=6.34s) spin

S. A. Rinehart, J. R. Houck, J. D. Smith

We present the first medium-resolution ($R\sim 600$) mid-infrared (8-13.3\micron) spectra of 11 Be stars. A large number of lines are observed and identified in these spectra, including, as an example, 39 hydrogen recombination lines in the spectrum of $γ$ Cas. In the majority of our spectra, all of the observed lines are attributable to hydrogen recombinati

R. P. Fender, G. G. Pooley, P. Durouchoux, R. P. J. Tilanus

We present almost-simultaneous detections of Cygnus X-1 in the radio and mm regimes, obtained during the low/hard X-ray state. The source displays a flat spectrum between 2 and 220 GHz, with a spectral index flatter than 0.15 (3sigma). There is no evidence for either a low- or high-frequency cut-off, but in the mid-infrared (~30 microns) thermal emission fro

Pedro Augusto, J. Ignacio Gonzalez-Serrano, Alastair C. Edge, Nectaria A. B. Gizani

We are conducting a multi-wavelength (radio, optical, and X-ray) observational campaign to classify, morphologically and physically, a sample of 55 flat-spectrum radio sources dominated by structure on kpc-scales. This sample contains 22 compact-/medium-sized symmetric object candidates, a class of objects thought to be the early stages of the evolution of r

Ewa L. Lokas

I apply the modified spherical infall model to test the dependence of the shape of density profiles of dark matter halos on redshift. The model predicts that the density profile of a halo of a given mass steepens with time and its concentration parameter changes like c~1/(1+z_0)^2.

E. Sadler, T. Oosterloo, R. Morganti

We present HI data cubes of four low-luminosity early-type galaxies which are currently forming stars. These galaxies have absolute magnitudes in the range M_B=-17.9 to -19.9 (H_o=50 km/s/Mpc). Their HI masses range between a few times 10^8 and a few times 10^9 M_sun and the corresponding values for M_HI/L_B are between 0.07 and 0.42, so these systems are HI

Jurgen Knodlseder, Miguel Cervino, Daniel Schaerer, Peter von Ballmoos

OB associations and young open clusters constitute the most prolific nucleosynthesis sites in our Galaxy. The combined activity of stellar winds and core-collapse supernovae ejects significant amounts of freshly synthesised nuclei into the interstellar medium. Radioactive isotopes, such as 26Al or 60Fe, that have been co-produced in such events may eventuall

M. N. Chernodub

We investigate string solutions to the classical equations of motion (&#34;classical QCD strings&#34;) for a dual Ginzburg-Landau model corresponding to SU(3) gluodynamics in an abelian projection. For a certain relation between couplings of the model the string solutions are defined by first order differential equations. These solutions are related to vorte

D. V. Shantsev, Y. M. Galperin, T. H. Johansen

Magnetization hysteresis loops and the ac susceptibility of a superconducting thin disk are calculated in the critical-state model assuming a field-dependent critical current density, Jc(B). The results are obtained by solving numerically the set of coupled integral equations for the flux and current distributions [PRB 60(17) p.13112 (1999)] for a disk place