September 2000 arXiv papers — page 13

M. Genovese, G. Brida, C. Novero, E. Predazzi

In this paper we describe a test of Bell inequalities using a non- maximally entangled state, which represents an important step in the direction of eliminating the detection loophole. The experiment is based on the creation of a polarisation entangled state via the superposition, by use of an appropriate optics, of the spontaneous fluorescence emitted by tw

Xiao-Gang He, B. J. McKellar

We study the Aharonov-Casher (AC) effect and the related He-McKellar-Wilkens (HMW) effect in 2+1 dimensions. In this restricted space these effects are the result of the interaction of the electromagnetic field tensor with the dual of a current. Transferring the dual operation from the current to the field tensor shows that this interaction may be reinterpre

K. Hallatschek, D. Biskamp

3D Braginskii turbulence simulations show that the energy flux in the core/edge transition region of a tokamak is strongly modulated - locally and on average - by radially propagating, nearly coherent sinusoidal or solitary zonal flows. The flows are geodesic acoustic modes (GAM), which are primarily driven by the Stringer-Winsor term. The flow amplitude tog

G. Vazquez, C. Camara, S. Putterman, K. Weninger

The Spectrum of the light emitted by a sonoluminescing bubble is extremely well fit by the spectrum of a blackbody. Furthermore the radius of emission can be smaller than the wavelength of the light. Consequences, for theories of sonoluminescence are discussed.

A. D. Jackson, A. Lande, B. Lautrup

The apparent superluminal propagation of electromagnetic signals seen in recent experiments is shown to be the result of simple and robust properties of relativistic field equations. Although the wave front of a signal passing through a classically forbidden region can never move faster than light, an attenuated replica of the signal is reproduced ``instanta

L. V. Fil'kov, V. L. Kashevarov, E. S. Konobeevski, M. V. Mordovskoy

An analysis of experimental data, obtained at the Linear Accelerator of INR, is carried out with the aim of searching for supernarrow dibaryons in the reactions pd->p+X and pd->p+pX_1. Dibaryons with masses 1904\pm 2, 1926\pm 2, and 1942\pm 2 MeV have been observed in M_{X} missing mass spectra. In M_{X_1} missing mass spectra, the peaks have been found at M

P. von Brentano, A. Dewald, C. Friessner, A. F. Lisetskiy

The data on low spin states in the odd-odd nucleus 50Mn investigated with the 50Cr(p,ngamma)50Mn fusion evaporation reaction at the FN-TANDEM accelerator in Cologne are reported. Shell model and collective rotational model interpretations of the data are given.

S. Liran, A. Marinov, N. Zeldes

A highly extrapolatable semiempirical shell model mass equation applicable to translead elements up to Z=126 is presented. The equation is applied to the recently discovered superheavy nuclei with Z=118 and A=293 and with Z=114 and A=289 and their decay products.

A. Bonasera, T. Maruyama, S. Chiba

We discuss the dynamics of finite systems within molecular dynamics models. Signatures of a critical behavior are analyzed and compared to experimental data both in nucleus-nucleus and metallic cluster collisions. We suggest the possibility to explore the instability region via tunneling. In this way we can obtain fragments at very low temperatures and densi

Tomaz Prosen

Spectral analysis of the {\em adjoint} propagator in a suitable Hilbert space (and Lie algebra) of quantum observables in Heisenberg picture is discussed as an alternative approach to characterize infinite temperature dynamics of non-linear quantum many-body systems or quantum fields, and to provide a bridge between ergodic properties of such systems and the

Giulio Casati, Tomaz Prosen

We study an area preserving parabolic map which emerges from the Poincar\' e map of a billiard particle inside an elongated triangle. We provide numerical evidence that the motion is ergodic and mixing. Moreover, when considered on the cylinder, the motion appear to follow a gaussian diffusive process.

Jean-Pierre Eckmann, Martin Hairer

We consider the stochastic Ginzburg-Landau equation in a bounded domain. We assume the stochastic forcing acts only on high spatial frequencies. The low-lying frequencies are then only connected to this forcing through the non-linear (cubic) term of the Ginzburg-Landau equation. Under these assumptions, we show that the stochastic PDE has a unique invariant

Shantilal G. Goradia

The fact that mass has an effect on surrounding space is the first essential element of general relativity. This paper unifies this mass/space distinction of general relativity with Newtonian gravity at a subatomic scale and with reported experimental findings of the last century. The subatomic distinction of mass concentration mainly in nucleons surrounded

Valeri V. Dvoeglazov

Recently, several discussions on the possible observability of 4-vector potential have been published in literature. Furthermore, several authors recently claimed existence of the helicity=0 electromagnetic field. We re-examine the theory of antisymmetric tensor field and 4-vector potentials. We study the massless limits too. In fact, a theoretical motivatio

Matilde Marcolli, Bai-Ling Wang

This is the second part of the proof of the exact traiangles in Seiberg-Witten Floer theory. We analyse the splitting and gluing of flow lines of the Chern-Simons-Dirac functional when the underlying three-manifold splits along a torus. (two corrections added)

Joachim Rosenthal, Xiaochang Wang

Let $M$ be a square matrix and let $p(t)$ be a monic polynomial of degree $n$. Let $Z$ be a set of $n\times n$ matrices. The multiplicative inverse eigenvalue problem asks for the construction of a matrix in $Z$ such that the product matrix $MZ$ has characteristic polynomial $p(t)$. In this paper we provide new necessary and sufficient conditions when $Z$ is

Daniel Grieser, Michael J Gruber

The Singular Asymptotics Lemma by Brüning and Seeley and the Push-Forward Theorem by Melrose lie at the very heart of their respective approaches to singular analysis. We review both and show that they deal with the same basic problem, giving solutions that emphasize different aspects of it. This also points to a possible common extension.

Ioannis Gasparis

Let X be an L_1-predual space and let K be a countable linearly independent subset of the extreme points of its closed dual ball. It is shown that if the norm-closed linear span Y of K is w^*-closed in X^*, then Y is the range of a w^*-continuous contractive projection in X^*. This result is applied in order to provide new and simpler proofs of the results o

Matilde Marcolli, Bai-Ling Wang

Some aspects of the construction of SW Floer homology for manifolds with non-trivial rational homology are analyzed. In particular, the case of manifolds that are obtained as zero-surgery on a knot in a homology sphere, and for torsion spinc structures. We discuss relative invariants in the case of torsion spinc structures.

A. G. Kovalev, M. A. Singer

We give new and rather general gluing theorems for anti-self-dual (ASD) conformal structures, following the method suggested by Floer. The main result is a gluing theorem for pairs of conformally ASD manifolds `joined' across a common piece (union of connected components) of their boundaries. This theorem genuinely operates in the b-category (in the sens

Matilde Marcolli, Bai-Ling Wang

This is the third part of the work on the exact triangles. We construct chain homomorphisms and show exactness of the resulting sequence.

Maurizio Parton

The aim of this paper is to write an explicit orthonormal parallelization for all parallelizable products of spheres, using an explicit isomorphism with a trivial vector bundle.

Y. Henrio

Let R be a complete discrete valuation ring of mixed characteristics, with algebraically closed residue field k. We study the existence problem of equivariant liftings to R of Galois covers of nodal curves over k. Using formal geometry, we show that this problem is actually a local one. We apply this local-to-global principle to obtain new results concerning

P. Freitas

We build a one-parameter family of S^{1}-invariant metrics on the unit disc with fixed total area for which the second eigenvalue of the Laplace operator in the case of both Neumann and Dirichlet boundary conditions is simple and has an eigenfunction with a closed nodal line. In the case of Neumann boundary conditions, we also prove that this eigenfunction a

Bilal Khan

The Hanna Neumann conjecture states that if F is a free group, then for all finitely generated subgroups H,K <= F, rank(H intersect K) - 1 <= [ rank(H)-1 ] [ rank(K)-1 ] In this paper, we show that if one of the subgroups, say H, has a generating set consisting of only positive words, then H is not part of any counterexample to the conjecture. We further sho

Kenneth Bromberg, John Holt

Let $N$ be a hyperbolic 3-manifold and $B$ a component of the interior of $AH(π_1(N))$, the space of marked hyperbolic 3-manifolds homotopy equivalent to $N$. We will give topological conditions on $N$ sufficient to give $ρ\in \bar{B}$ such that for every small neighborhood $V$ of $ρ$, $V \cap B$ is disconnected. This implies that $\bar{B}$ is not manifold w

Kenneth Bromberg

In this paper we extend Thurston&#39;s hyperbolic Dehn surgery theorem to a class of geometrically infinite hyperbolic 3-manifolds. As an application we prove a modest density theorem for Kleinian groups. We also discuss hyperbolic Dehn surgery on geometrically finite hypebolic cone-manifolds.

Nicolas Perrin

In this article we prove the irreducibility of the Hilbert scheme of rationnal curves on homogeneous varieties with fixed class in the Chow ring. This result has also been proved by J. F. Thomsen [T] and B. Kim and R. Pandharipande [KP]. Our method is totaly different (we don&#39;t use the compactification of stable maps) and enables us to prove the existenc

Xi Chen

We study the following question: fix a sufficient general curve D of degree d in P^2, what is the least number of intersections between D and an irreducible curve of degree m? G. Xu proved this number i(d, m) is at least d - 2 for all m. This problem can be regarded as the algebraic part of Kobayashi conjecture on the hyperbolicity of P^2 D. We first improve

Stefano Monni, Jun S. Song, Yun S. Song

We use algebraic methods to compute the simple Hurwitz numbers for arbitrary source and target Riemann surfaces. For an elliptic curve target, we reproduce the results previously obtained by string theorists. Motivated by the Gromov-Witten potentials, we find a general generating function for the simple Hurwitz numbers in terms of the representation theory o

Hael Collins, Bob Holdom

We study the behavior of a general gravitational action, including quadratic terms in the curvature, supplemented by a compact scalar field in 4+1 dimensions. The generalized Einstein equation for this system admits solutions which are compact in one direction and Poincare invariant in the remaining directions. These solutions do not require any fine-tuning

Steven S. Gubser, Indrajit Mitra

We exhibit a tachyonic mode in a linearized analysis of perturbations of large anti-de Sitter Reissner-Nordstrom black holes in four dimensions. In the large black hole limit, and up to a 0.7% discrepancy which is probably round-off error in the numerical analysis, the tachyon appears precisely when the black hole becomes thermodynamically unstable.

P. F. Borges, H. Boschi-Filho, C. Farina

We show that Bose-Einstein condensation of charged scalar fields interacting with a topological gauge field at finite temperature is inhibited except for special values of the topological field. We also show that fermions interacting with this topological gauge field can condense for some values of the gauge field.

Dirk Prange

We derive new examples for algebraic relations of interacting fields in local perturbative quantum field theory. The fundamental building blocks in this approach are time ordered products of free (composed) fields. We give explicit formulas for the construction of Poincare covariant ones, which were already known to exist through cohomological arguments. For

Henri Verschelde

We introduce the 2PPI expansion which sums the bubble graphs to all orders. We show that this expansion can be renormalised with the usual counterterms in a mass independent scheme. We discuss its application to the O(N) linear sigma model.

A. Cappelli, G. D&#39;Appollonio, R. Guida, N. Magnoli

Several pieces of evidence have been recently brought up in favour of the c-theorem in four and higher dimensions, but a solid proof is still lacking. We present two basic results which could be useful for this search: i) the values of the putative c-number for free field theories in any even dimension, which illustrate some properties of this number; ii) th

Jian Jing, Ming Yu

Motivated by superstring theories on $AdS_3$, we construct spacetime superconformal algebras (SCAs) living on the $AdS_3$ boundary in terms of the transversal physical degrees of freedom. The SCAs constructed are N=4 large, middle algebras, and N=3 algebra, corresponding to superstring theories on $AdS_3 \times S ^3 \times S^3 \times S ^1$, $AdS_3 \times S ^

C. Merino, S. J. Brodsky, J. Rathsman

We propose the asymmetry in the fractional energy of charm versus anticharm jets produced in high energy diffractive photoproduction as a sensitive test of the interference of the Odderon (C = -) and Pomeron (C = +) exchange amplitudes in QCD. If measured at HERA, this asymmetry could provide the first experimental evidence of the Odderon.

William B. Kilgore, Walter T. Giele

We present results of a next-to-leading order calculation of three jet production at hadron colliders. This calculation will have many applications. In addition to computing such three-jet observables as spectra, mass distributions, this calculation permits the first next-to-leading order studies at hadron colliders of jet and event shape variables.

Elmar Bittner, Maria-Paola Lombardo, Harald Markum, Rainer Pullirsch

We investigate the eigenvalue spectrum of the staggered Dirac matrix in two-color QCD at nonzero temperature and at baryon density when the eigenvalues become complex. The quasi-zero modes and their role for chiral symmetry breaking and the deconfinement transition are examined. The bulk of the spectrum and its relation to quantum chaos is considered. Compar

Stephen R. Cotanch, Felipe J. Llanes-Estrada

We represent QCD at the hadronic scale by means of an effective Hamiltonian, H, formulated in the Coulomb gauge. As in the Nambu-Jona-Lasinio model, chiral symmetry is dynamically broken, however our approach is renormalizable and also includes confinement through a linear potential with slope specified by lattice gauge theory. We perform a comparative study

Ian Low

We discuss the possibility of extracting |V_{ub}| from various spectra of inclusive B decays, without large systematic errors which usually arise from having to model the Fermi motion of the heavy quark. This strategy can be applied to the electron energy spectrum, as well as the hadronic mass spectrum. Modulo violation of local hadron-parton duality, the th

N. N. Nikolaev, V. R. Zoller

The recent progress in color BFKL-Regge phenomenology of small-x DIS on nucleons, pions and photons is reviewed

N. N. Nikolaev

I review the modern status of QCD theory of diffractive vector meson production with the focus on shrinkage of photons with Q2 and (Q2+mV2)$scaling, j-plane properties of the QCD pomeron and Regge shrinkage of diffraction cone, $s$-channel helicity non-conservation and sensitivity to spin-orbital properties of vector mesons.

Nguyen Anh Ky, Hoang Ngoc Long, Le Phuoc Trung, Dang Van Soa

Contribution from new gauge bosons in the 3 - 3 - 1 models to the anomalous magnetic moment of the muon, mass difference of the kaon system and rare kaon decay are calculated and numerically estimated. Bounds on masses of new gauge bosons: bileptons and Z&#39; are derived.

W. Porod

We have studied the reconstruction of supersymmetric theories at high scales by evolving the fundamental parameters from the electroweak scale upwards. Universal minimal supergravity and gauge mediated supersymmetry breaking have been taken as representative alternatives. Pseudo-fixed point structures require the low-energy boundary values to be measured wit

Mayumi Aoki, Noriyuki Oshimo

We discuss a supersymmetric extension of the standard model with an extra U(1) gauge symmetry. In this model, the proton stability is guaranteed by the gauge symmetry without invoking R parity. The gauge symmetry breakdown automatically generates an effective $μ$ term and large Majorana masses for right-handed neutrinos. The supersymmetry-soft-breaking terms

Cristina Manuel

We review the non-Fermi or marginal liquid behavior of a relativistic QED plasma. In this medium a quasiparticle has a damping rate that depends linearly on the distance between its energy and the Fermi surface. We stress that this dependence is due to the long-range character of the magnetic interactions in the medium. Finally, we study how the quark dampin

T. Teshima, T. Asai

We assume the universal Yukawa coupling (democratic mass matrix) with small violations for quarks, charged leptons and neutrinos masses. We could reproduce the mass hierarchy for quark masses and V_{CKM} matrix elements precisely. We adopt the see-saw mechanism for the explanation of smallness of neutrino masses and introduce the right-handed Majorana neutri

Iain W. Stewart

The application of renormalization group techniques to bound states in non-relativistic QED and QCD is discussed. For QED bound states like Hydrogen and positronium, the renormalization group allows large logarithms of the velocity, ln v (or equivalently ln alpha&#39;s), to be predicted in a universal and simple way. The series of (alpha ln alpha)&#39;s are

Giuseppe Di Carlo, Roberto Scimia

In the framework of a non-compact lattice regularization of nonabelian gauge theories we look, in the SU(2) case, for the scaling window through the analysis of the ratio of two masses of hadronic states. In the two-dimensional parameter space of the theory we find the region where the ratio is constant, and equal to the one in the Wilson regularization. In

A. Valassi

An overview of measurements of Bose-Einstein correlations in W-pair events at LEP is given. The results presented are based on data collected at centre-of-mass energies between 172 and 202GeV. The review concentrates on the search for Bose-Einstein correlations between pions from different W&#39;s in e+e- -> W+W- -> qqbarqqbar events. No agreement is reached

M. Yu. Zotov

Recently, Byland and Scialom studied the evolution of the Bianchi I, the Bianchi III and the Kantowski-Sachs universe on the basis of dynamical systems methods (Phys. Rev. D57, 6065 (1998), gr-qc/9802043). In particular, they have pointed out a problem to determine the stability properties of one of the degenerate critical points of the corresponding dynamic

D. R. Matravers, N. P. Humphreys

Conditions for smooth cosmological models are set out and applied to inhomogeneous spherically symmetric models constructed by matching together different Lemaitre-Tolman-Bondi solutions to the Einstein field equations. As an illustration the methods are applied to a collapsing dust sphere in a curved background. This describes a region which expands and the

Kazuhiro Tominaga, Motoyuki Saijo, Kei-ichi Maeda

We study gravitational waves from a spinning test particle scattered by a relativistic star using a perturbation method. The present analysis is restricted to axial modes. By calculating the energy spectrum, the waveforms and the total energy and angular momentum of gravitational waves, we analyze the dependence of the emitted gravitational waves on a partic

Caroline Santos

We study static black hole solutions in scalar tensor gravity. We present exact solutions in hiperextended models with a quadratic scalar potential.

R. H. Heffner, J. E. Sonier, D. E. MacLaughlin, G. J. Nieuwenhuys

We report predominantly zero field muon spin relaxation measurements in a series of Ca-doped LaMnO_3 compounds which includes the colossal magnetoresistive manganites. Our principal result is a systematic study of the spin-lattice relaxation rates 1/T_1 and magnetic order parameters in the series La_{1-x}Ca_xMnO_3, x = 0.0, 0.06, 0.18, 0.33, 0.67 and 1.0. In

A. Prigent, O. Dauchot

Investigations of counter-rotating Taylor-Couette flow (TCF) in the narrow gap limit are conducted in a very large aspect ratio apparatus. The phase diagram is presented and compared to that obtained by Andereck et al. The spiral turbulence regime is studied by varying both internal and external Reynolds numbers. Spiral turbulence is shown to emerge from the

Sergey Novikov

Effect of static charges on charge carrier transport in disordered organic materials is considered. Long range nature of Coulomb interaction requires to take into consideration a finite thickness of the transport layer. Presence of conducting electrodes significantly modifies properties of organic medium, removes a long range Coulomb divergence, and makes it

Frantisek Slanina, Yi-Cheng Zhang

We study a new evolutionary game, where players are tempted to take part by the premium, but compete for being the first who take a specific move. Those, who manage to escape the bulk of players, are the winners. While for large premium the game is very similar to the Minority Game studied earlier, significant new behavior, reminiscent of spin glasses is obs

A. K. Zhuravlev, M. I. Katsnelson

An accurate numerical consideration of 1D spinless fermion model with next-nearest neighbour (NNN) interactions is carried out for the electron concentrations 4/7. It is shown that depending on the parameters of the model it can be either Luttinger liquid or bipolaron liquid. In the former case competing interactions can result in a smooth behavior of one-el

A. F. Barabanov, R. Hayn, A. A. Kovalev, O. V. Urazaev

A semi-phenomenological approach to describe the evolution of Fermi surface (FS) and electronic structure with doping is presented which is based on the spin-fermion model. The doping is simulated by a frustration term in the spin Hamiltonian and the complex internal structure of the spin-polaron quasiparticle is taken into account by a superposition of spin

Amin Jazaeri, Indubala I. Satija

A class of one-dimensional lattice models with incommensurate complex potential $V(θ)=2[λ_r cos(θ)+i λ_i sin(θ)]$ is found to exhibit localization transition at $|λ_r|+|λ_i|=1$. This transition from extended to localized states manifests in the behavior of the complex eigenspectum. In the extended phase, states with real eigenenergies have finite measure and

Kicheon Kang, Sam Young Cho, Ju-Jin Kim, Sung-Chul Shin

An interacting quantum dot side-coupled to a perfect quantum wire is studied. Transport through the quantum wire is investigated by using an exact sum rule and the slave-boson mean field treatment. It is shown that the Kondo effect provides a suppression of the transmission due to the destructive interference of the ballistic channel and the Kondo channel. A

L. Saviot, E. Duval, J. F. Jal, A. J. Dianoux

Low-frequency Raman and inelastic neutron scattering of amorphous bis-phenol A polycarbonate is measured at low temperature, and compared. The vibrational density of states and light-vibration coupling coefficient are determined. The frequency dependences of these parameters are explained by propagating vibration modes up to an energy of about 1 meV, and fra

I. Mirebeau, M. Hennion, H. Casalta, H. Andres

Original paper from Mirebeau et al. PRL 83, 628, 1999 Comment from W. Bao et al (cond-mat/0008042, 2 Aug 2000 submitted to PRL, updated on 1 sep 2000

T. Brandes, F. Renzoni

We propose a new transport mechanism through tunnel-coupled quantum dots based on the coherent population trapping effect. Coupling to an excited level by the coherent radiation of two microwaves can lead to an extremely narrow current antiresonance. The effect can be used to determine interdot dephasing rates and is a mechanism for a very sensitive, optical

G. L. Buchbinder

The hydrodynamic equations for a crystals with interstitials, taking into account the dissipative processes of the viscosity, heat conduction and the interstitial diffusion are derived. To achieve that we use the phenomenological approach has originally been applied in the theory of the superfluids for the derivation of equations of the two-fluid hydrodynami

Cailin A. Nelson, Peter P. Eggleton

We undertake a comparison of observed Algol-type binaries with a library of computed Case A binary evolution tracks. The library consists of 5500 binary tracks with various values of initial primary mass M_{10}, mass ratio q_0, and period P_0, designed to sample the phase-space of Case A binaries in the range -0.10 < log M_{10} < 1.7. Each binary is evolved

Patrick S. Wojdowski, Duane A. Liedahl, Masao Sako

We analyze the ASCA spectrum of the Cen X-3 X-ray binary system in eclipse using atomic models appropriate to recombination-dominated level population kinetics in an overionized plasma. In order to estimate the wind characteristics, we first fit the eclipse spectrum to a single-zone photoionized plasma model. We then fit spectra from a range of orbital phase

Qingjuan Yu, Scott Tremaine

We investigate resonant capture of small bodies by planets that migrate inwards, using analytic arguments and three-body integrations. If the orbits of the planet and the small body are initially circular and coplanar, the small body is captured when it crosses the 2:1 resonance with the planet. As the orbit shrinks it becomes more eccentric, until by the ti

Hannah Jang-Condell, Lars Hernquist

We describe the results of a simulation of collisionless cold dark matter in a LambdaCDM universe to examine the properties of objects collapsing at high redshift (z=10). We analyze the halos that form at these early times in this simulation and find that the results are similar to those of simulations of large scale structure formation at low redshift. In p

Witold Maciejewski

Motivated by STIS observations of more than 50 nearby galactic nuclei, we consider long-slit emission-line spectra when the slit is wider than the instrumental PSF. The finite width of the slit generates complex patterns in the spectra that can have considerable diagnostic power if they are modeled with adequate sophistication. They allowed us to develop a n

Gibor Basri

I present the results of a multiyear survey of very low mass stars and brown dwarfs, at high spectral resolution. The spectra were gathered with the HIRES echelle at the Keck Observatory. Some of these objects are stellar and others are substellar (or ambiguous). Early indications that such objects can be rapidly rotating but display little H-alpha emission

L. T. Barone, E. Molinari, H. Boehringer, G. Chinarini

After the completion of the catalogue built with ESO key program (REFLEX), we are beginning to explore the multiband optical characteristics of a subsample of those clusters selected in a statistically independent way. We have already observed in B, V, R, 9 of the about 50 clusters of the subsample, with 0.15 \le z \le 0.18. More time has been allocated by E

Tim de Zeeuw

Masses of black holes in nearby galactic nuclei can be measured in a variety of ways, using stellar and gaseous kinematics. Reliable black hole masses are known for several dozen objects, so that demographic questions can start to be addressed with some confidence. Prospects for the near future are discussed briefly.

Ben Moore, Vicent Quilis, Richard Bower

The observed morphological evolution since z ~ 0.5 within galaxy clusters provides evidence for a hierarchical universe. This evolution is driven by dynamical effects that operate within the cluster environment -- suppression of star-formation by ram-pressure and viscous stripping of the intra-galactic medium and tidal heating of disks by gravitational encou

Ben Moore

I review four decades of numerical simulations of galaxy clusters focussing on the attempts to resolve their internal structure. Overmerging describes the numerical or physical disruption of dark matter halos within dense environments. This problem was inherent in simulations prior to 1998 but can be completely overcome with current algorithms and hardware.

Paolo A. Mazzali

The spectrum of the normal Type Ia SN 1990N observed very early on (14 days before B maximum) was analysed by Fisher et al (1997), who showed that the large width and the unusual profile of the strong line near 6000Åcan be reproduced if the line is assumed to be due to \CII 6578, 6583Åand if Carbon is located in a high velocity shell. This line is one of the

N. K. Spyrou, N. Stergioulas

The spin-down of a millisecond pulsar in a compact binary system leads to self-energy losses, that cause the binary&#39;s orbital period to increase (the effect being of first post-Newtonian (1PN) order). If the pulsar&#39;s period-derivative is not exceedingly small, this effect can become measurable in long-term high-precision timing measurements of the bi

G. Bjornsson, E. J. Lindfors

In a recent paper, Rol and colleagues present evidence for a variable polarization in the optical afterglow following the gamma-ray burst GRB 990712. The variation is highly significant, but the position angle appears time independent. Contrary to their conclusion, we point out that this can in fact be explained with existing afterglow models, namely that of

E. Andres, P. Askebjer, X. Bai, G. Barouch

This paper briefly summarizes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector. The complete data set from 1997 was analyzed. For E_mu>10 TeV, the detector exceeds 10,000 m^2 in effective area between declinations of 25 and 90 degrees. Neutrinos generated in the atmosphere by cosmic ray interactions were used to veri

Xinwu Cao, D. R. Jiang

We explore the relationship between the extended radio and line emission for a radio-loud quasar sample including both core-dominated and lobe-dominated quasars. A strong correlation is present between the extended radio and broad-line emission. The core emission is also correlated with the broad-line emission for core-dominated quasars in the sample. The st

Xinwu Cao, Y. D. Xu, J. H. You

Recently, Narayan & Raymond (1999) proposed that the thermal emission lines from the hot plasma in advection dominated accretion flows (ADAFs) are potentially observable with the next generation of X-ray observatories, with which the physical properties of some X-ray sources can be probed. In ADAFs, the temperature of the ion is so high that the thermal broa

Shih-Ping Lai, You-Hua Chu, C. H. Rosie Chen, Robin Ciardullo

The SNR candidate MF83 in M101 is coincident with a very luminous X-ray source. Based on the high X-ray luminosity, it has been suggested that MF83 is a &#34;hypernova remnant&#34; requiring an explosion energy about two orders of magnitude higher than normal supernovae. We have analyzed high-quality ground-based and HST observations of MF83, and find that M

Jimmy A. Irwin, Joel N. Bregman

We have derived azimuthally-averaged radial iron abundance profiles of the X-ray gas contained within 12 clusters of galaxies with redshift 0.03 < z < 0.2 observed with BeppoSAX. We find evidence for a negative metal abundance gradient in most of the clusters, particularly significant in clusters that possess cooling flows. The composite profile from the 12

S. J. Kannappan, D. G. Fabricant

We search for bulk counterrotation of the gas and stars in 67 galaxies of all types and a wide range of luminosities. Bulk counterrotation characterizes \~25-30% of E/S0&#39;s with extended gas, but at most a few percent of Sa-Sbc spirals. For S0&#39;s, the frequency of counterrotation we derive agrees with previous work, but we sample significantly fainter

S. J. Kannappan, D. G. Fabricant

We analyze asymmetries in the gas rotation curves of 113 galaxies drawn from the Nearby Field Galaxy Survey, spanning a broad range of luminosities and morphologies. If the origin of the rotation curve is chosen to minimize the asymmetry, then ~23% of sample galaxies show asymmetry >5% within 1.3r_e. However, not all gas kinematic asymmetries indicate asymme

S. J. Kannappan, D. G. Fabricant

We measure the frequency of bulk gas-stellar counterrotation in a sample of 67 galaxies drawn from the Nearby Field Galaxy Survey, a broadly representative survey of the local galaxy population down to M_B-15. We detect 4 counterrotators among 17 E/S0&#39;s with extended gas emission (24% +8 -6). In contrast, we find no clear examples of bulk counterrotation

B. Noheda, D. E. Cox, G. Shirane, S-E. Park

The origin of ultrahigh piezoelectricity in the relaxor ferroelectric PbZn1/3Nb2/3O3-PbTiO3 was studied with an electric field applied along the [001] direction. The zero-field rhombohedral R phase starts to follow the direct polarization path to tetragonal symmetry via an intermediate monoclinic M phase, but then jumps irreversibly to an alternate path invo

N. R. Pantoja, H. Rago

A regularization procedure, that allows one to relate singularities of curvature to those of the Einstein tensor without some of the shortcomings of previous approaches, is proposed. This regularization is obtained by requiring that (i) the density $|det {\bf g}|^{1/2}G^a_{b}$, associated to the Einstein tensor $G^a_{b}$ of the regularized metric, rather tha

Filipe Freire, Daniel F. Litim, Jan M. Pawlowski

We discuss gauge symmetry and Ward-Takahashi identities for Wilsonian flows in pure Yang-Mills theories. The background field formalism is used for the construction of a gauge invariant effective action. The symmetries of the effective action under gauge transformations for both the gauge field and the auxiliary background field are separately evaluated. We

Roger G. Melko, Byron C. den Hertog, Michel J. P. Gingras

Recently it has been suggested that long range magnetic dipolar interactions are responsible for spin ice behavior in the Ising pyrochlore magnets ${\rm Dy_{2}Ti_{2}O_{7}}$ and ${\rm Ho_{2}Ti_{2}O_{7}}$. We report here numerical results on the low temperature properties of the dipolar spin ice model, obtained via a new loop algorithm which greatly improves t

Kang Li, Carlos M. Naón

By introducing a doublet of electromagnetic four dimensional vector potentials, we set up a manifestly Lorentz covariant and SO(2) duality invariant classical field theory of electric and magnetic charges. In our formulation one does not need to introduce the concept of Dirac string.

V. A. Miransky, I. A. Shovkovy, L. C. R. Wijewardhana

The Bethe-Salpeter equations for diquarks with the quantum numbers of the Nambu-Goldstone bosons are analyzed in the color-flavor locked phase of cold dense QCD with three quark flavors. The decay constants and the velocities of the Nambu-Goldstone bosons are calculated in the Pagels-Stokar approximation. It is also shown that, in contrast to the case of den

D. Blume, Chris H. Greene

The diffusion Monte Carlo method is applied to describe a trapped atomic Bose-Einstein condensate at zero temperature, fully quantum mechanically and nonperturbatively. For low densities, $n(0)a^3 \le 2 \cdot 10^{-3}$ [n(0): peak density, a: s-wave scattering length], our calculations confirm that the exact ground state energy for a sum of two-body interacti

O. Scavenius, A. Dumitru, E. S. Fraga, J. T. Lenaghan

We discuss homogeneous nucleation in a first-order chiral phase transition within an effective field theory approach to low-energy QCD. Exact decay rates and bubble profiles are obtained numerically and compared to analytic results obtained with the thin-wall approximation. The thin-wall approximation overestimates the nucleation rate for any degree of super

J. Piilo, K. -A. Suominen, K. Berg-Sorensen

We have simulated binary collisions between atoms in optical lattices during Sisyphus cooling. Our Monte Carlo Wave Function simulations show that the collisions selectively accelerate mainly the hotter atoms in the thermal ensemble, and thus affect the steady state which one would normally expect to reach in Sisyphus cooling without collisions.

Ulrich Heinz

I review the status of the search for quark-gluon plasma in relativistic heavy-ion collisions. The available data provide strong evidence for the "three pillars of the Little Bang model": strong radial expansion of the collision fireball with Hubble-like scaling, thermal hadron emission and primordial hadrosynthesis. It is argued that the initial state of th

M. C. Arnesen, S. Bose, V. Vedral

We investigate the entanglement between any two spins in a one dimensional Heisenberg chain as a function of temperature and the external magnetic field. We find that the entanglement in an antiferromagnetic chain can be increased by increasing the temperature or the external field. Increasing the field can also create entanglement between otherwise disentan