March 1999 arXiv papers — page 18

Neven Bilic, Raoul D. Viollier

A system of self-gravitating massive fermions is studied in the framework of the general-relativistic Thomas-Fermi model. We study the properties of the free energy functional and its relation to Einstein's field equations. A self-gravitating fermion gas we then describe by a set of Thomas-Fermi type self-consistency equations.

M. P. Lilly, K. B. Cooper, J. P. Eisenstein, L. N. Pfeiffer

We recently reported [PRL 82, 394 (1999)] large transport anisotropies in a two-dimensional electron gas in high Landau levels. These observations were made utilizing both square and Hall bar sample geometries. Simon recently commented [cond-mat/9903086] that a classical calculation of the current flow in the sample shows a magnification of an underlying ani

F. Ronning, C. Kim, D. L. Feng, D. S. Marshall

An angle resolved photoemission study on Ca2CuO2Cl2, a parent compound of high Tc superconductors is reported. Analysis of the electron occupation probability, n(k) from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant even

Eric Jeckelmann, Chunli Zhang, Steven R. White

We study the one-dimensional Holstein model with spin-1/2 electrons at half-filling. Ground state properties are calculated for long chains with great accuracy using the density matrix renormalization group method and extrapolated to the thermodynamic limit. We show that for small electron-phonon coupling or large phonon frequency, the insulating Peierls gro

Patrik Henelius, Anders W. Sandvik, Carsten Timm, S. M. Girvin

We present quantum Monte Carlo results for the field and temperature dependence of the magnetization and the spin-lattice relaxation rate $1/T_1$ of a two-dimensional $S=1/2$ quantum Heisenberg ferromagnet. The Monte Carlo method, which yields results free of systematic errors, is described in detail. The high accuracy of the calculated magnetization allows

Nicola Marzari, David Vanderbilt, Alessandro De Vita, M. C. Payne

Al(110) has been studied for temperatures up to 900 K via ensemble density-functional molecular dynamics. The strong anharmonicity displayed by this surface results in a negative coefficient of thermal expansion, where the first interlayer distance decreases with increasing temperature. Very shallow channels of oscillation for the second-layer atoms in the d

R. Raimondi, P. Schwab, C. Castellani

The calculation of the dephasing time in electron systems is presented. By means of the Keldysh formalism we discuss in a unifying way both weak localization and interaction effects in disordered systems. This allows us to show how dephasing arises both in the particle-particle channel (weak localization) and in the particle-hole channel (interaction effect)

R. Baviera, D. Vergni, A. Vulpiani

In this paper we test the random walk hypothesis on the high frequency dataset of the bid--ask Deutschemark/US dollar exchange rate quotes registered by the inter-bank Reuters network over the period October 1, 1992 to September 30, 1993. Then we propose a stochastic model for price variation which is able to describe some important features of the exchange

A. Villares Ferrer, A. O. Caldeira

Exploring a classical solution of the non-linear sigma model for a quantum Hall ferromagnet, a skyrmion-magnon effective hamiltonian is obtained via the collective coordinates method. Using the Feynman-Vernon functional integral formalism for this model we find the temperature dependent transport coefficients which characterize a single skyrmion dynamics.

Kirill Ilinski

In this short note we discuss recent attempts to describe pre-crash market dynamics with analogies from theory of critical phenomena.

Pablo Jensen

This paper presents a comprehensive analysis of simple models useful to analyze the growth of nanostructures obtained by cluster deposition. After detailing the potential interest of nanostructures, I extensively study the first stages of growth (the submonolayer regime) by kinetic Monte-Carlo simulations. These simulations are performed in a wide variety of

Michal Rokni, Y. Levinson

We describe the interaction of surface acoustic waves with electrons in an array of quantum wires, patterned out of a two dimensional electron gas. Two specific geometries are considered, in which the surface acoustic wave travels parallel, or perpendicular to the wires. Although we assume the electron wave functions in different wires do not overlap, the sc

Jian-Sheng Wang

We discuss two important techniques, series expansion and Monte Carlo simulation, for random sequential adsorption study. Random sequential adsorption is an idealization for surface deposition where the time scale of particle relaxation is much longer than the time scale of deposition. Particles are represented as extended objects which are adsorbed to a con

Y. Tanaka, S. Kashiwaya

To reveal the influence of the exchange interaction on the Josephson effect, the d.c. Josephson current in unconventional-superconductor / ferromagnet / unconventional-superconductor junctions is studied. When the two superconductors have d-wave symmetry, the Josephson current is drastically suppressed with the increase of the exchange interaction. On the ot

Qijin Chen, Ioan Kosztin, Boldizsar Janko, K. Levin

We investigate the behavior of the superconducting transition temperature within a previously developed BCS-Bose Einstein crossover picture. This picture, based on a decoupling scheme of Kadanoff and Martin, further extended by Patton, can be used to derive a simple form for the superconducting transition temperature in the presence of a pseudogap. We extend

P. Castiglione, M. Cencini, A. Vulpiani, E. Zambianchi

In the framework of chaotic scattering we analyze passive tracer transport in finite systems. In particular, we study models with open streamlines and a finite number of recirculation zones. In the non trivial case with a small number of recirculation zones a description by mean of asymptotic quantities (such as the eddy diffusivity) is not appropriate. The

I. Arad, L. Biferale, I. Mazzitelli, I. Procaccia

We address scaling in inhomogeneous and anisotropic turbulent flows by decomposing structure functions into their irreducible representation of the SO(3) symmetry group which are designated by $j,m$ indices. Employing simulations of channel flows with Re$_λ\approx 70$ we demonstrate that different components characterized by different $j$ display different s

Nahum Arav, Robert H. Becker, Sally A. Laurent-Muehleisen, Michael D. Gregg

We find that the depth and shape of the broad absorption lines (BALs) in BALQSO 1603+3002 are determined largely by the fraction of the emitting source which is covered by the BAL flow. In addition, the observed depth of the BALs is poorly correlated with their real optical depth. The implication of this result is that abundance studies based on direct extra

J. Vinko, L. L. Kiss, J. Thomson, G. Furesz

Medium resolution spectroscopic observations of SN 1998aq made in April-May, 1998, are presented. We confirm its Type Ia classification based on the prominent Si II 6355 A line and other features similar to SNe Ia. No significant sign of hydrogen Balmer-alpha line was seen in high-resolution spectra taken at 8 days before maximum. Preliminary estimate of red

C. Burigana, D. Maino, N. Mandolesi, F. Villa

We simulate Planck observations by adopting a detailed model of the microwave sky including monopole, dipole, anisotropies of the cosmic microwave background (CMB) and galactic and extragalactic foregrounds. We estimate the impact of main beam optical aberrations on CMB anisotropy measurements in presence of extragalactic source fluctuations and we discuss t

B. G. Elmegreen, Y. N. Efremov, R. E. Pudritz, H. Zinnecker

Young stars form on a wide range of scales, producing aggregates and clusters with various degrees of gravitational self-binding. The loose aggregates have a hierarchical structure in both space and time that resembles interstellar turbulence, suggesting that these stars form in only a few turbulent crossing times with positions that map out the previous gas

A. Lancon, M. Mouhcine, M. Fioc, D. Silva

Based on evolutionary spectral synthesis models explicitly including the spectra of variable AGB stars, we select near-IR features that dentify the strong O-rich or C-rich AGB contributions to the near-IR light of post-starburst populations. AGB temperature scales and lifetimes remain major sources of uncertainties. We discuss applications and suggest massiv

A. J. Young, C. S. Crawford, A. C. Fabian, W. N. Brandt

We report on a short optical monitoring programme of the narrow-line Seyfert 1 Galaxy IRAS 13224-3809. Previous X-ray observations of this object have shown persistent giant variability. The degree of variability at other wavelengths may then be used to constrain the conditions and emission processes within the nucleus. Optical variability is expected if the

Istvan Szapudi, Alexander S. Szalay

We describe a set of new estimators for the N-point correlation functions of point processes. The variance of these estimators is calculated for the Poisson and binomial cases. It is shown that the variance of the unbiased estimator converges to the continuum value much faster than with any previously used alternative, all terms with slower convergence exact

N. Robichon, F. Arenou, J. -C. Mermilliod, C. Turon

New memberships, mean parallaxes and proper motions of all 9 open clusters closer than 300 pc (except the Hyades) and 9 rich clusters between 300 and 500 pc have been computed using Hipparcos data. Precisions, ranging from 0.2 to 0.5 mas for parallaxes and 0.1 to 0.5 mas/yr for proper motions, are of great interest for calibrating photometric parallaxes as w

Laerte Sodre, Grazyna Stasinska

We have analyzed the emission line properties in the integrated spectra of 15 normal spiral galaxies. We show that very clear trends appear when plotting relevant emission line ratios or equivalent widths as a function of galaxy spectral types, obtained with a Principal Component Analysis of the continua and absorption features of spectra. The equivalent wid

Mercedes Molla, Jean-Rene Roy

NGC 1313 is the most massive disk galaxy showing a flat radial abundance distribution in its interstellar gas, a behavior generally observed in magellanic and irregular galaxies. We have attempted to reproduce this flat abundance distribution using a multiphase chemical evolution model, which has been previously used sucessfully to depict other spiral galaxi

N. A. J. Schutgens, G. Toth

We present numerical simulations, obtained with the Versatile Advection Code, of the oscillations of an inverse polarity prominence. The internal prominence equilibrium, the surrounding corona and the inert photosphere are well represented. Gravity and thermodynamics are not taken into account, but it is argued that these are not crucial. The oscillations ca

Wenfei Yu, Tipei Li, Mei Wu

We have investigated the bimodal distribution of the duration of BATSE gamma-ray bursts (GRBs) by analyzing light curves of 64 ms time resolution. We define the average pulse width of GRBs from the auto-correlation function of GRB profiles. The distribution of the average pulse width of GRBs is bimodal, suggesting that GRBs are composed of long-pulse GRBs an

A. Magazzu, G. Umana, E. L. Martin

We present a 8.4 GHz VLA survey of 50 optical counterparts to 46 ROSAT All-Sky survey (RASS) X-ray sources south of the Taurus-Auriga star-forming region. This survey detected 3 sources with a sensitivity limit of ~ 0.12 mJy. Merging our sample with other radio observations of sources in and around Taurus-Auriga, we find scarce radio emission among RASS sour

Martin Lemoine, Guenter Sigl, Peter Biermann

We predict energy spectra and angular distributions of nucleons above 10**(19) eV that originate from sources distributed in the Local Supercluster, which is also supposed to contain a large scale magnetic field of strength between 0.05 and 0.5 micro Gauss. We show that this model can explain all present-day features of ultra-high energy cosmic rays, at leas

L. Ciotti

In the context of the study of the properties of the mutual mass distribution of the bright and dark matter in elliptical galaxies, present a family of two-component, spherical, self-consistent galaxy models, where one density distribution follows a gamma_1 profile, and the other a gamma_2 profile [(gamma_1,gamma_2) models], with different total masses and `

M. Villar-Martin, L. Binette, R. A. E. Fosbury

We present UV rest frame spectra of 3 powerful narrow line radio galaxies and the hyperluminous type 2 active galaxy SMM02399-0136, all at high redshift (z>2). We find high velocities (FWHM>1000, km/s) in the extended gas of all objects. A natural explanation is the interaction between the radio jet and the ambient gas, that drives shocks into the gas and ac

Paola Andreani, Andrea Cimatti, Huub Roettgering, Remo Tilanus

Preliminary results of a project aiming at unveiling the nature of the extremely red galaxies (ERGs) (objects with colours R-K>6 and I-K>5) found in deep optical-NIR surveys are presented. Very little is known about these objects, the critical issue being whether they are old ellipticals at z>1 or distant star-forming galaxies strongly reddened by dust extin

Michael W. Wise, Craig L. Sarazin

We have calculated the emergent X-ray properties for models of cluster cooling flows including the effects of accumulated cooled material. The opacity of this cooled gas can reduce the overall X-ray luminosity of the cooling flow, and values of Mdot based on these luminosities can underestimate the true value by factors of ~2. We find that accumulated cooled

D. A. Leahy, H. Marshall

Observations of Her X-1 by the Extreme Ultraviolet Explorer (EUVE) at the end of the x-ray Short High state are reported here. Her X-1 is found to exhibit a strong orbital modulation of the EUV flux, with a large dip superposed on a broad peak around orbital phase 0.5 when the neutron star is closest the observer. Alternate mechanisms for producing the obser

Alvio Renzini

Clusters of galaxies allow a direct estimate of the metallicity and metal production yield on the largest scale so far. The ratio of the total iron mass in the ICM to the total optical luminosity of the cluster (the iron mass-to-light-ratio) is the same for all clusters which ICM is hotter than $\sim 2$ keV, and the elemental proportions (i.e. the [$α$/Fe] r

A. Y. Potekhin, Yu. A. Shibanov, J. Ventura

We study partially ionized hydrogen plasma at temperatures T = 10^{5.5}-10^{6.5} K and magnetic fields B = 10^{12}-10^{13} G, typical of photospheres of isolated neutron stars. We construct an analytic model of the plasma free energy and derive a generalized Saha equation which is used to obtain the opacities.

I. V. Lavrinenko, H. Lu, C. N. Pope, K. S. Stelle

The gauge transformations of p-form fields in supergravity theories acquire a non-commuting character when one introduces potentials both for the theory's original field strengths and for their duals. This has previously been shown in the ``doubled'' formalism for maximal supergravities, where a generalised duality relation between original and d

Ivan Schmidt, Jian-Jun Yang

We discuss QCD condensate contributions to the gluon propagator both in the fixed-point gauge and in covariant gauges for the external QCD vacuum gluon fields with the conclusion that a covariant gauge is essential to obtain a gauge invariant QCD vacuum energy density difference and to retain the unitarity of the quark scattering amplitude. The gauge-invaria

E. Solano, C. L. Cesar, R. L. de Matos Filho, N. Zagury

We study a method for the implementation of a reliable teleportation protocol (theoretically, 100% of success) of internal states in trapped ions. The generation of the quantum channel (any of four Bell states) may be done respecting technical limitations on individual addressing and without claiming the Lamb-Dicke regime. An adequate Bell analyzer, that tra

S. Mano

A conformal field theory on the boundary of three-dimensional asymptotic anti-de Sitter spaces which appear as near horizon geometry of D-brane bound states is discussed. It is shown that partition functions of gravitational instantons appear as high and low temperature limits of the partition function of the conformal field theory. The result reproduces pha

W. Schadow, Ch. Elster, W. Gloeckle

The Faddeev equation for three-body scattering below the three-body breakup threshold is directly solved without employing a partial wave decomposition. In the simplest form it is a three-dimensional integral equation in four variables. From its solution the scattering amplitude is obtained as function of vector Jacobi momenta. Based on Malfliet-Tjon type po

E. Pian, L. Amati, L. A. Antonelli, R. C. Butler

We present BeppoSAX GRBM and WFC light curves of GRB980425 and NFI follow-up data taken in 1998 April, May, and November. The first NFI observation has detected within the 8' radius error box of the GRB an X-ray source positionally consistent with the supernova SN 1998bw, exploded within a day of GRB980425, and a fainter X-ray source, not consistent with

C. A. A. de Carvalho, R. M. Cavalcanti

We derive the semiclassical series for the partition function in Quantum Statistical Mechanics (QSM) from its path integral representation. Each term of the series is obtained explicitly from the (real) minima of the classical action. The method yields a simple derivation of the exact result for the harmonic oscillator, and an accurate estimate of ground-sta

J. Froehlich, G. M. Graf, J. Walcher

Properties of eigenstates of one-particle Quantum Hall Hamiltonians localized near the boundary of a two-dimensional electron gas - so-called edge states - are studied. For finite samples it is shown that edge states with energy in an appropriate range between Landau levels remain extended along the boundary in the presence of a small amount of disorder, in

Kai Hencken, Dirk Trautmann, Gerhard Baur

We study the spectrum of the bremsstrahlung photons coming from the electrons and positrons, which are produced in the strong electromagnetic fields present in peripheral relativistic heavy ion collisions. We compare different approaches, making use of the exact pair production cross section in heavy ion collisions as well as the double equivalent photon app

Robert A. Herrmann

Using mathematical techniques to model one of the most simplistic of human linguistic processes, it is rationally predicted that within the nonstandard physical world (NSP-world) there exists a force-like (logical) operator *S and an entity w' such that *S{w'} sequentially generates each of the Natural systems that comprise a Universe. This model sho

Barbara Coluzzi, Marc Mezard, Giorgio Parisi, Paolo Verrocchio

We compute the thermodynamic properties of the glass phase in a binary mixture of soft spheres. Our approach is a generalization to mixtures of the replica strategy, recently proposed by Mezard and Parisi, providing a first principle statistical mechanics computation of the thermodynamics of glasses. The method starts from the inter-atomic potentials, and tr

A. A. Andrianov, V. A. Andrianov, R. Rodenberg

The effective quark models with quasilocal interaction are used for description of two composite Higgs doublets, in strong coupling (tricritical) regime below the compositeness scale Λ_{C}. The low energy effective action of Two-Higgs Doublet Standard Model (2HD SM) is obtained in the large N_c and large-log approximation. The two-point correlators of scalar

Silvio Franz, Federico Ricci-Tersenghi

We perform an accurate test of Ultrametricity in the aging dynamics of the three dimensional Edwards-Anderson spin glass. Our method consists in considering the evolution in parallel of two identical systems constrained to have fixed overlap. This turns out to be a particularly efficient way to study the geometrical relations between configurations at distan

M. Frank, H. Hamidian, K. Puolamaki

We explore the phenomenology of supersymmetric SO(10) grand unified theories with gauge mediated supersymmetry breaking. We show that if SO(10) breaking proceeds through intermediate left-right symmetric gauge groups which are broken at the supersymmetry breaking scale, then perturbative unification allows the existence of only a few consistent models with v

S. Massar, R. Parentani

We rephrase the derivation of black hole radiation so as to take into account, at the level of transition amplitudes, the change of the geometry induced by the emission process. This enlarged description reveals that the dynamical variables which govern the emission are the horizon area and its conjugate time variable. Their conjugation is established throug

H. L. Lai, J. Huston, S. Kuhlmann, J. Morfin

An up-to-date global QCD analysis of high energy lepton-hadron and hadron-hadron interactions is performed to better determine the gluon and quark parton distributions in the nucleon. Improved experimental data on inclusive jet production, in conjunction with precise deep inelastic scattering data, place good constraints on the gluon over a wide range of x;

J. C. Mattingly, Ya. G. Sinai

We give a geometric approach to proving know regularity and existence theorems for the 2D Navier-Stokes Equations. We feel this point of view is instructive in better understanding the dynamics. The technique is inspired by constructions in the Dynamical Systems.

M. Adler, P. van Moerbeke

Consider a symmetric (finite) matrix ensemble, with a certain probability distribution. What is the probability that the spectrum belongs to a certain interval or union of intervals on the real line? In this paper, we show that, upon introducing an appropriate time parameter, this probability is intimately related to Pfaffians, which as a vector satisfy the

K. Banaszek, C. Radzewicz, K. Wodkiewicz, J. S. Krasinski

We report a direct measurement of the Wigner function characterizing the quantum state of a light mode. The experimental scheme is based on the representation of the Wigner function as an expectation value of a displaced photon number parity operator. This allowed us to scan the phase space point-by-point, and obtain the complete Wigner function without usin

A. Flores, G. Ruffini, A. Rius, E. Cardellach

Ionospheric tomography using GPS data has been reported in the literature and even the application to radar altimeter calibration was succesfully carried out in a recent work. We here present a new software tool, called Global Ionospheric Stochastic Tomography software (GIST), and its powerful capability for ingesting GPS data from different sources (ground

E. G. Bessonov

In this paper we explore some surprising consequences of the retardation effects of Maxwell's electrodynamics to a system of charged particles. The specific cases of three interacting particles are considered in the framework of classical electrodynamics. We show that the solutions of the equations of motion defined by the Darvin Lagrangian in some cases

Michael K. Murray, Michael A. Singer

The discrete Nahm equations, a system of matrix valued difference equations, arose in the work of Braam and Austin on half-integral mass hyperbolic monopoles. We show that the discrete Nahm equations are completely integrable in a natural sense: to any solution we can associate a spectral curve and a holomorphic line-bundle over the spectral curve, such that

P. T. Leung, W. -M. Suen, C. P. Sun, K. Young

Dissipative quantum systems are sometimes phenomenologically described in terms of a non-hermitian hamiltonian $H$, with different left and right eigenvectors forming a bi-orthogonal basis. It is shown that the dynamics of waves in open systems can be cast exactly into this form, thus providing a well-founded realization of the phenomenological description a

Oscar Arratia, Miguel A. Martin, Mariano A. Olmo

This paper investigates the classical and quantum elementary systems with Newton-Hoooke symmetry. A complete classification is given by explicit computation. In addition, we present an application example of quantization using the Moyal scheme.

S. Ivashkovich, V. Shevchishin

We give a proof of the Gromov compactness theorem using the language of stable curves (i.e. cusp-curve of Gromov, or stable maps of Kontsevich and Manin) in general setting: An almost complex structure on a target manifold is only continuous and can vary; the curves are only assumed to have fixed ``topological type'', in particular they can be non-cl

Gerd Schmalz, Jan Slovak

The general theory of parabolic geometries is applied to the study of the normal Cartan connections for all hyperbolic and elliptic 6-dimensional CR-manifolds of codimension two. The geometric meaning of the individual components of the torsion is explained and the chains of dimensions one and two are discussed. This seems to be the first application of the

Daisuke Matsushita

In this note, we prove that every fibre space structures of a projective irreducible symplectic manifold is a lagrangian fibration.

Osamu Fujino

Let $(X,Δ)$ be a proper dlt pair and $L$ a nef Cartier divisor such that $aL-(K_X+Δ)$ is nef and log big on $(X,Δ)$ for some $a\in {\mathbb Z}_{>0}$. Then $|mL|$ is base point free for every $m\gg 0$.

Osamu Fujino

In this paper we treat some applications of Kawamata's positivity theorem. We get a weak answer to \cite [Section 3]{KeMaMc}. And we investigate the singularities on the target spaces of some morphisms.

Akikazu Hashimoto, N. Itzhaki

Using the spectral representation approach to the Zamolodchikov's c-function and the Maldacena conjecture for the D1-branes, we compute the entropy of type IIB strings. An agreement, up to a numerical constant which cannot be determined using this approach, with the Bekenstein-Hawking entropy is found.

Anastasia Doikou, Rafael I. Nepomechie

We formulate a systematic Bethe-Ansatz approach for computing bound-state (``breather'') S matrices for integrable quantum spin chains. We use this approach to calculate the breather boundary S matrix for the open XXZ spin chain with diagonal boundary fields. We also compute the soliton boundary S matrix in the critical regime.

Jean-Pierre Derendinger

An effective supergravity description of all instabilities of N_4=4 superstrings is derived. The construction is based on the N_4=4 BPS mass formula at finite temperature and uses the properties of N_4=4 gauged supergravity. It provides the boundaries of the various thermal phases in the non-perturbative moduli space. It also draws a precise picture of the d

Ludger Hannibal

We show that the solutions of SU(2) Yang-Mills-dilation and Einstein-Yang-Mills-dilaton theories described in a sequence of papers by Kleihaus and Kunz are not regular in the gauge field part.

Hiroaki Terashima

We present a simple and systematic method to calculate the Rindler noise, which is relevant to the analysis of the Unruh effect, by using the fluctuation-dissipative theorem. To do this, we calculate the dissipative coefficient explicitly from the equations of motion of the detector and the field. This method gives not only the correct answer but also a hint

Kei Ito

Duality between N=1 supersymmetric gauge theories(Seiberg's duality) is geometrized, in the framework of AdS/CFT correspodences. It is shown that Seiberg's duality corresponds to monodromy of wrapped D5 branes on the homology cycles of a generalized conifold where D3 branes are located. The celebrated \tilde{N}_c=N_f-N_c, \tilde{N}_f=N_f rule is repr

P. K. Townsend

The M(atrix) model has a dual realization as IIA superstring theory in the near-horizon geometry of the supergravity D0-brane. The role of $adS_2$ in this correspondence is reviewed, and some aspects of holography that it suggests are discussed.

Esteban Calzetta, Bei Lok Hu

The aim of this paper is two-fold: in probing the statistical mechanical properties of interacting quantum fields, and in providing a field theoretical justification for a stochastic source term in the Boltzmann equation. We start with the formulation of quantum field theory in terms of the Schwinger - Dyson equations for the correlation functions, which we

Milton Dean Slaughter

We utilize non-perturbative and fully relativistic methods to calculate the\thinspace \thinspace $ΔNγ$ electromagnetic transition amplitudes $G_{M}^{*}(q^{2})$ (related to the magnetic dipole moment $% M_{1^{+}}^{3/2}(q^{2})$), $G_{E}^{*}(q^{2})$ (related to the electric quadrupole moment $E_{1^{+}}^{3/2}(q^{2})$), the electromagnetic ratio $% R_{EM}(q^{2})\

M. Gluck, E. Reya, I. Schienbein

Using constituent quark model constraints we calculate the gluon and sea-quark content of pions solely in terms of their valence density (fixed by πN Drell-Yan data) and the known sea and gluon distributions of the nucleon, using the most recent updated valence-like input parton densities of the nucleon. The resulting small-x dynamical QCD predictions for g^

E. J. Chun, D. Comelli, David H. Lyth

We study in detail a supersymmetric Peccei-Quinn model, which has a DFSZ and a KSVZ version. The fields breaking the Peccei-Quinn (PQ) symmetry correspond to flat directions (flaton fields) and have unsuppressed couplings when PQ symmetry is unbroken. The models have interesting particle physics phenomenology. The PQ scale is naturally generated through radi

B. Kubis, T. R. Hemmert, Ulf-G. Meißner

We calculate the form factors of the baryon octet in the framework of heavy baryon chiral perturbation theory. The calculated charge radius of the $Σ^-$ is in agreement with recent measurements from CERN and Fermilab. We show that kaon loop effects can play a significant role in the neutron electric form factor. Furthermore. we derive generalized Caldi-Pagel

Gudrun Hiller, Gino Isidori

We present a detailed estimate of the transverse muon polarization (P_T) due to electromagnetic final-state interactions in the decay $K^+ \to μ^+ νγ$. This CP-conserving effect represents the dominant contribution to P_T within the Standard Model. As a result of an explicit calculation, we find that the CP-conserving contribution to P_T is quite small, typi

R. L. Jaffe, D. Kharzeev

We consider the production and decay of the $χ_2$ charmonium state in polarized and unpolarized $pp$ collisions at RHIC in the framework of an effective theory based on the QCD multipole expansion. We find that the angular distribution in the decay of the produced charmonium, $χ_2 \to J/ψ+ γ$, in the unpolarized case allows us to distinguish clearly between

F. Gliozzi, P. Provero

We point out that the world sheet swept by the confining string in presence of dynamical quarks can belong to two different phases, depending on the number of charge species and the quark masses. When it lies in the normal phase (as opposed to the tearing one) the string breaking is invisible in the Wilson loop, while is manifest in operators composed of dis

K. S. Cheng, Y. Li, W. -M. Suen

We study the thermal evolution of a pulsar after a glitch in which the energy is released from a relative compact region. A set of relativistic thermal transport and energy balance equations is used to study the thermal evolution, without making the assumption of spherical symmetry. We use an exact cooling model to solve this set of differential equtions. Ou

P. T. Leung, Y. T. Liu, W. -M. Suen, C. Y. Tam

Using a recently developed perturbation theory for uasinormal modes (QNM's), we evaluate the shifts in the real and imaginary parts of the QNM frequencies due to a quasi-static perturbation of the black hole spacetime. We show the perturbed QNM spectrum of a black hole can have interesting features using a simple model based on the scalar wave equation.

P. T. Leung, Y. T. Liu, W. -M. Suen, C. Y. Tam

Quasinormal mode (QNM) gravitational radiation from black holes is expected to be observed in a few years. A perturbative formula is derived for the shifts in both the real and the imaginary part of the QNM frequencies away from those of an idealized isolated black hole. The formulation provides a tool for understanding how the astrophysical environment surr

Miguel Alcubierre, Bernd Brugmann, Mark Miller, Wai-Mo Suen

We propose a re-formulation of the Einstein evolution equations that cleanly separates the conformal degrees of freedom and the non-conformal degrees of freedom with the latter satisfying a first order strongly hyperbolic system. The conformal degrees of freedom are taken to be determined by the choice of slicing and the initial data, and are regarded as giv

Ion I. Cotăescu

The problem of the quantum modes of the scalar free field on anti-de Sitter backgrounds with an arbitrary number of space dimensions is considered. It is shown that this problem can be solved by using the same quantum numbers as those of the nonrelativistic oscillator and two parameters which give the energy quanta and respectively the ground state energy. T

K. A. Bronnikov, C. P. Constantinidis, R. L. Evangelista, J. C. Fabris

We study the possible existence of charged and neutral black holes in the Bergmann-Wagoner class of scalar-tensor theories (STT) of gravity in four dimensions. The existence of black holes is shown for anomalous versions of these theories, with a negative kinetic term in the Lagrangian. The Hawking temperature of these holes is zero, while the horizon area i

K. Karlsson, O. Gunnarsson, O. Jepsen

We have studied the Cu core level photoemission spectra in the Anderson impurity model for cuprates with different Cu-O networks, dimensionalities (zero, one, two and three) and Cu valencies (two and three). We focus on the shape of the leading peak and obtain very good agreement with the experimental data. We show how the shape of the spectrum is related to

David Vanderbilt

Recent theoretical advances have established that the electric polarization in an insulating crystal can be viewed as a multivalued quantity that is determined by certain Berry phases associated with the occupied Bloch bands. The application of this approach to the computation of piezoelectric coefficients is not entirely straightforward, since a naive deter

Daniel A. Stariolo, Sergio A. Cannas

The violation of the Fluctuation-Dissipation Theorem (FDT) in a two-dimensional Ising model with both ferromagnetic exchange and antiferromagnetic dipolar interactions is established and investigated via Monte Carlo simulations. Through the computation of the autocorrelation C(t+t_w,t_w) and the integrated response (susceptibility) functions we obtain the FD

M. Tsuchiizu, Y. Suzumura

A role of umklapp scattering has been examined for two-coupled chains with both forward and backward scatterings by applying renormalization group method to bosonized Hamiltonian. It has been found that a state with relevant interchain hopping changes into a state with irrelevant (confined) one when the magnitude of umklapp scattering becomes larger than tha

Yu. I. Latyshev, S. -J. Kim, T. Yamashita

We developed the focused ion beam (FIB) and ion milling techniques for a fabrication of the Bi_2Sr_2CaCu_2O_{8+δ} (Bi-2212) stacked junctions with in-plane size L_{ab} from several microns down to the submicron scale without degradation of T_c. We found that behaviour of submicron junctions (L_{ab} < 1 μm) is quite different from the bigger ones. The critica

Marc Thilo Figge, Maxim Mostovoy, Jasper Knoester

We study the magnetic response due to neutral solitons induced by disorder in polymer materials. We account for interchain interactions, which, if sufficiently strong, result in a bond-ordered phase, in which the neutral solitons are bound into pairs. We analytically calculate the corresponding pair size distribution. As the spins of the solitons have a dist

Jesper Lykke Jacobsen

Fully packed loop models on the square and the honeycomb lattice constitute new classes of critical behaviour, distinct from those of the low-temperature O(n) model. A simple symmetry argument suggests that such compact phases are only possible when the underlying lattice is bipartite. Motivated by the hope of identifying further compact universality classes

Juan M. Lopez, Jose J. Ramasco, Miguel A. Rodriguez

We comment on a recent Letter by Braunstein and Buceta [PRL vol.81, 630 (1998)], in which a novel equation has been proposed to describe the dynamics of interfaces in the presence of quenched disorder. We argue that the ansatz Braunstein and Buceta presented is just an effective description of the very short times regime and has no significance for the macro

Toshiaki Iitaka, Toshikazu Ebisuzaki

We propose an efficient linear-scaling time-dependent method for calculating nonlinear response function, and study the size effects in non-degenerate two photon absorption spectra of Si nanocrystallites by using semi-empirical pseudopotentials.

Karl-Peter Marzlin, Weiping Zhang

We study the spontaneous emission of a partially excited Bose-Einstein condensate composed of two-level atoms. The formation of polaritons induced by the ground-state part of the condensate leads to an avoided crossing in the photon spectrum. This avoided crossing acts similarly to a photonic band gap and modifies the spontaneous emission rate.

Akira Oguri

The dc conductance through a finite Hubbard chain of size N coupled to two noninteracting leads is studied at T = 0 in an electron-hole symmetric case. Assuming that the perturbation expansion in U is valid for small N (=1,2,3,...) owing to the presence of the noninteracting leads, we obtain the self-energy at ω= 0 analytically in the real space within the s

J. H. Han, P. Ao, X. -M. Zhu

We calculate the effective mass of a single quantized vortex in the BCS superconductor at finite temperature. Using the effective action for a vortex, we arrive at the mass formula as the integral of the spectral function $J(ω)/ω^3$ over frequency. The spectral function is given in terms of the transition elements of the gradient of the Hamiltonian between B