September 2001 arXiv papers — page 4

A. I. Larkin, B. I. Shklovskii

It is shown that the voltage dependence of the tunneling conductance between two lightly doped semiconductors, which are separated by an large area tunneling barrier, can reveal the high energy part of the Coulomb gap if the barrier is thick enough. At the barrier thickness smaller than average distance between impurities no Coulomb gap feature can be found.

Claudio Attaccalite, Saverio Moroni, Paola Gori-Giorgi, Giovanni B. Bachelet

The ground state energy of the two--dimensional uniform electron gas has been calculated with fixed--node diffusion Monte Carlo, including backflow correlations, for a wide range of electron densities as a function of spin polarization. We give a simple analytic representation of the correlation energy which fits the density and polarization dependence of th

Martin E. Beer, Philipp Podsiadlowski

We describe the theory and implementation of a three-dimensional fluid dynamics code which we have developed for calculating the surface geometry and circulation currents in the secondaries of interacting binary systems. The main method is based on an Eulerian-Lagrangian scheme to solve the advective and force terms in Euler's equation. Surface normalise

Vittorio Giovannetti, Lorenzo Maccone, Jeffrey H. Shapiro, Franco N. C. Wong

It is shown that parametric downconversion, with a short-duration pump pulse and a long nonlinear crystal that is appropriately phase matched, can produce a frequency-entangled biphoton state whose individual photons are coincident in frequency. Quantum interference experiments which distinguish this state from the familiar time-coincident biphoton state are

M. Ramspeck, U. Heber, H. Edelmann

We present the result of differential spectral analyses of a further four apparently normal B-type stars. Abundance anomalies (e.g. He, C, N enrichment), slow rotation and/or high gravities suggest that the programme stars are evolved low-mass B-type stars. In order to trace their evolutionary status several scenarios are discussed. Post-AGB evolution can be

Uriel Frisch, Sabino Matarrese, Roya Mohayaee, Andrei Sobolevski

Reconstructing the density fluctuations in the early Universe that evolved into the distribution of galaxies we see today is a challenge of modern cosmology [ref.]. An accurate reconstruction would allow us to test cosmological models by simulating the evolution starting from the reconstructed state and comparing it to the observations. Several reconstructio

Gabriel A. Durkin, Christoph Simon, Dik Bouwmeester

Multi-photon states from parametric down-conversion can be entangled both in polarization and photon number. Maximal high-dimensional entanglement can be concentrated from these states via photon counting. This makes them natural candidates for quantum key distribution, where the presence of more than one photon per detection interval has up to now been cons

Luis Anchordoqui, Haim Goldberg

The existence of extra degrees of freedom beyond the electroweak scale may allow the formation of black holes in nearly horizontal neutrino air showers. In this paper we examine the average properties of the light descendants of these black holes. Our analysis indicates that black hole decay gives rise to deeply penetrating showers with an electromagnetic co

L. Benfatto, A. Toschi, S. Caprara, C. Castellani

We study the evolution of the superconducting coherence length $ξ_0$ from weak to strong coupling, both within a s-wave and a d-wave lattice model. We show that the identification of $ξ_0$ with the Cooper-pair size $ξ_{pair}$ in the weak-coupling regime is meaningful only for a fully-gapped (e.g., s-wave) superconductor. Instead in the d-wave superconductor,

D. V. Soroka, V. A. Soroka

It is shown that two definitions for the exterior differential in superspace, giving the same exterior calculus, when applied to the Poisson bracket lead to the different results. Examples of the even and odd linear brackets, corresponding to semi-simple Lie groups, are given and their natural connection with BRST and anti-BRST charges is indicated.

Tim Oliver Eynck, Eric Laenen, Lukas Phaf, Stefan Weinzierl

We compare the phase space slicing and dipole subtraction methods in the computation of the inclusive and differential next-to-leading order cross sections for heavy quark production in the simple process gamma^* -> Q Qbar. For the phase space slicing method we study the effects of improvement terms that remove restrictions on the slicing parameter s_min. Fo

L. Bonora, A. Sorin

Using cohomological methods we discuss several issues related to chiral anomalies in noncommutative U(N) YM theories in any even dimension. We show that for each dimension there is only one solution of the WZ consistency condition and that there cannot be any reducible anomaly, nor any mixed anomaly when the gauge group is a product group. We also clarify so

J. A. S. Lima, R. Silva, J. Santos

The concept of Jeans gravitational instability is rediscussed in the framework of nonextensive statistics and its associated kinetic theory. A simple analytical formula generalizing the Jeans criterion is derived by assuming that the unperturbed self- gravitating collisionless gas is kinetically described by the $q$-parameterized class of power law velocity

Bogusław Broda, Grzegorz Duniec

A practical implementation of the non-Abelian Stokes theorem for topologically nontrivial loops (knots) with possible intersections is proposed.

D. P. Bennett, A. C. Becker, J. L. Quinn, A. B. Tomaney

We present an analysis of the longest timescale microlensing events discovered by the MACHO Collaboration during a 7 year survey of the Galactic bulge. We find 6 events that exhibit very strong microlensing parallax signals due, in part, to accurate photometric data from the GMAN and MPS collaborations. The microlensing parallax fit parameters are used in a

Yakir Aharonov, Jeeva Anandan, Shmuel Nussinov

Re-considering this work.

Karen Windmeier Wetz

In 1948 H.B.G.Casimir predicted that an attractive force between two perfectly conducting neutral plates exists due to changes in the electromagnetic vacuum energy caused by the influence of the plates. In 1956 E.M. Lifshitz derived an extension of Casimir's expression applicable to finite temperatures and arbitrary dielectric constants for the two half-

A. D. Baute, I. L. Egusquiza, J. G. Muga

Using the concept of crossing state and the formalism of second quantization, we propose a prescription for computing the density of arrivals of particles for multiparticle states, both in the free and the interacting case. The densities thus computed are positive, covariant in time for time independent hamiltonians, normalized to the total number of arrival

Atsushi Miyauchi

Presented here is a matrix inversion method utilizing quantum searching algorithm. In this method, huge Hilbert space as a whole spanned by myriad of eigen states is searched and evaluated efficiently by sequential reduction in dimension one by one. Total iteration steps required for search are proportional to the number of unknown variables. Our method coul

Lov K. Grover, Anirvan Sengupta

Quantum search is a quantum mechanical technique for searching N possibilities in only sqrt(N) steps. This paper gives a fresh perspective on the algorithm in terms of a resonance phenomenon which is implemented through classical coupled oscillators. Consider N oscillators, one of which is of a different resonant frequency. We could identify which one this i

I. N. Filikhin, V. A. Roudnev, S. L. Yakovlev, B. Vlahovic

The characteristics of the four $^4$He atom cluster are investigated using the differential equations for Yakubovsky components. Binding energy, mean-square radius and density function are calculated for the ground state.The spatial properties of the cluster and its subsystems are studied.

Pierre Desesquelles

This article introduces recursive relations allowing the calculation of the number of partitions with constraints on the minimum and/or on the maximum fragment size.

A. Chikanian, L. E. Finch, R. S. Longacre, J. Sandweiss

We discuss the problem of observing spontaneous parity and CP violation in collision systems. We discuss and propose observables which may be used in heavy-ion collisions to observe such violations, as well as event-by-event methods to analyze the data. Finally, we discuss simple monte-carlo models of these CP violating effects which we have used to develop

J. M. Udias, Javier R. Vignote, E. Moya de Guerra, A. Escuderos

A comparison of impulse approximation calculations for the (e,e'p) reaction, based on the Dirac equation and the Schrodinger one is presented. Trivial (kinematics) differences are indicated, as well as how to remove them from the standard nonrelativistic formalism. Signatures of the relativistic approach are found where the enhancement of the lower compo

Qingfeng Li, Zhuxia Li

We have studied equilibration with respect to isospin degree of freedom in four 96 mass systems $^{96}Ru+^{96}Ru$, $^{96}Ru+^{96}Zr$, $^{96}Zr+^{96}Ru$, $^{96}Zr+^{96}Zr$ at 100 AMeV and 400 AMeV with isospin dependent QMD. We propose that the neutron-proton differential rapidity distribution is a sensitive probe to the degree of equilibration with respect t

Bao-An Li, Andrew T. Sustich, Matt Tilley, Bin Zhang

The isospin-dependence of mechanical and chemical instabilities is investigated within a thermal and nuclear transport model using a Skyrme-type phenomenological equation of state for neutron-rich matter. Respective roles of the nuclear mean field and the 2-body stochastic scattering on the evolution of density and isospin fluctuations in either mechanically

A. E. Kudryavtsev, V. E. Tarasov, B. L. Berman, W. J. Briscoe

We discuss the experimental and theoretical status of charge-symmetry violation (CSV) in the elastic scattering of pi+ and pi- on 3H and 3He. Analysis of the experimental data for the ratios r1, r2, and R at Tpi = 142, 180, 220, and 256 MeV provides evidence for the presence of CSV. We describe pion scattering from the three-nucleon system in terms of single

K. Filimonov

In 1999 the CERES/NA45 ran at the CERN SPS with a beam energy of 40 GeV/nucleon. The data set comprises about 8.7 millions Pb-Au events with a trigger selection corresponding to approximately the most central 30% of the geometrical cross section. Results on low-mass electron pair analysis are presented. The upgrade of the experimental setup with the radial d

Christian Fleischhack

It is proven that the physical measure for the two-dimensional Yang-Mills theory is purely singular with respect to the kinematical Ashtekar-Lewandowski measure. For this, an explicit decomposition of the gauge orbit space into supports of these two measures is given. Finally, the results are extended to more general (e.g. confining) theories. Such a singula

Miguel D. Bustamante, Sergio A. Hojman

In this work, we construct the general solution to the Heat Equation (HE) and to many tensor structures associated to the Heat Equation, such as Symmetries, Lagrangians, Poisson Brackets (PB) and Lagrange Brackets, using newly devised techniques that may be applied to any linear equation (e.g., Schroedinger Equation in field theory, or the small-oscillations

Stephen Berman, Chongying Dong, Shaobin Tan

In this paper we study the representation theory for certain ``half lattice vertex algebras.'' In particular we construct a large class of irreducible modules for these vertex algebras. We also discuss how the representation theory of these vertex algebras are related to the representation theory of some associative algebras.

Sung Ho Wang

We show the total space of the canonical line bundle $\mathbb{L}$ of a Kahler-Einstein manifold $X^n$ supports integrable $SU(n+1)$ structures, or Calabi-Yau structures. The canonical real line bundle $L \subset \mathbb{L}$ over a minimal Lagrangian submanifold $M \subset X$ is calibrated in this setting and hence can be considered as the special Lagrangian

Andrea Nahmod, Atanas Stefanov, Karen Uhlenbeck

We construct a gauge theoretic change of variables for the wave map from $R \times R^n$ into a compact group or Riemannian symmetric space, prove a new multiplication theorem for mixed Lebesgue-Besov spaces, and show the global well-posedness of a modified wave map equation - $n \ge 4$ - for small critical initial data. We obtain global existence and uniquen

Dan Voiculescu

Using simple operator-valued analytic function considerations several general analytic subordination results for a freely Markovian triple of operator algebras are derived from the analytic subordination result for generalized resolvents in the case of a free increment with amalgamation. This includes a generalization of Biane's subordination result in t

Wolfgang Ebeling

A relation is proved between the Poincaré series of the coordinate algebra of a two-dimensional quasihomogeneous isolated hypersurface singularity and the characteristic polynomial of its monodromy operator. For a Kleinian singularity not of type $A_{2n}$, this amounts to the statement that the Poincaré series is the quotient of the characteristic polynomial

Laurent Fargues

We generalize the work of M. Harris and R. Taylor on the local Langlands correspondence for the linear group over $\mathbb{Q}_p$. We prove some cases of the Kottwitz conjectures for the supercuspidal part of the compactly supported $\ell$-adic cohomology of Rapoport-Zink rigid-analytic spaces. This means that we decompose this part in terms of local Langland

J. Cassaigne, P. Hubert, S. Troubetzkoy

We establish a relationship between the word complexity and the number of generalized diagonals for a polygonal billiard. We conclude that in the rational case the complexity function has cubic upper and lower bounds. In the tiling case the complexity has cubic asymptotic growth.

Mark Hoffmann

We give an explicit computation of the Banach envelope for the Paley-Wiener type spaces $E^p, 0<p<1$. This answers a question by Joel Shapiro.

Helene Barcelo, Robert Maule, Sheila Sundaram

For a fixed positive integer n, let S_n denote the symmetric group of n! permutations on n symbols, and let maj(sigma) denote the major index of a permutation sigma. For positive integers k<m not greater than n and non-negative integers i and j, we give enumerative formulas for the cardinality of the set of permutations sigma in S_n with maj(sigma) congruent

Wolfgang Ebeling

In the author&#39;s paper &#39;&#39;Poincaré series and monodromy of a two-dimensional quasihomogeneous hypersurface singularity&#39;&#39; a relation is proved between the Poincaré series of the coordinate algebra of a two-dimensional quasihomogeneous isolated hypersurface singularity and the characteristic polynomial of its monodromy operator. We study this

Alfredo T. Suzuki, Ricardo Bentín

In the usual and current understanding of planar gauge choices for Abelian and non Abelian gauge fields, the external defining vector $n_μ$ can either be space-like ($n^2<0$) or time-like ($n^2>0$) but not light-like ($n^2=0$). In this work we propose a light-like planar gauge that consists in defining a modified gauge-fixing term, $\cal{L}_{GF}$, whose main

Yuji Igarashi, Katsumi Itoh, Hiroto So

Using the Pauli-Villars regularization, we make a perturbative analysis of the quantum master equation (QME), $\Sigma =0$, for the Wilsonian effective action. It is found that the QME for the UV action determines whether exact gauge symmetry is realized along the renormalization group (RG) flow. The basic task of solving the QME can be reduced to compute the

Ruo Peng Wang

A quantum Dirac field theory with no divergences of vacuum energy is presented. The vacuum energy divergence is eliminated by removing a extra degree of freedom of the Dirac fields. The conditions for removing the extra degree of freedom, expressed in the form of a conservation law and an orthogonality relation, define another spin 1/2 field with the same re

P. J. Bussey

At the HERA collider at DESY, high energy electron and positron beams interact with proton beams. A review is presented of the variety of ways in which these collisions produce final states containing charm and beauty quarks.

D. Kharzeev, A. Krasnitz, R. Venugopalan

We compute numerically the topological charge distribution in the initial stage of a high energy heavy ion collision. This charge distribution is generated by Chern-Simons number fluctuations associated with the dynamics of strong classical fields in the initial state. The distribution is found to be quite narrow at RHIC and LHC energies reflecting a small v

Zurab Tavartkiladze

Mechanism for generation of suppressed neutrino masses, within low scale theories, is considered. The mechanism do not have extradimensional nature and is realized through extended $SU(2)_L$ scalar multiplets. Latters, in some cases, are also crucial for successful low scale unification.

Th. Mannel, St. Wolf

We discuss the impact of the soft degrees of freedom inside the B_c meson on its rate in the semi-leptonic decay B_c -> X l nu_l where X denotes light hadrons below the D^0 threshold. In particular we identify contributions involving soft hadrons which are non-vanishing in the limit of massless leptons. These contributions become relevant for a measurement o

Ernest Ma

If the one term $(\hat ν_e \hat μ- \hat e \hat ν_μ) \hat τ^c$ is added to the MSSM (Minimal Supersymmetric Standard Model) superpotential, the recently observed muon g--2 (anomalous magnetic moment) excess can be explained very simply by a light $\tilde ν_e$. If the soft symmetry-breaking terms $\hat ν_α\hat h_2^0 - \hat l_α\hat h_2^+$ are also added, realis

Stefan W. Bosch

We discuss the exclusive radiative B-meson decays B -> K* gamma and B -> rho gamma in a model-independent manner. The analysis is based on the heavy-quark limit of QCD. This allows a factorization of perturbatively calculable contributions to the B -> V gamma matrix elements from non-perturbative form factors and universal light-cone distribution amplitudes.

D. Kazanas, A. Nicolaidis

We have proposed that the cosmic ray spectrum &#34;knee&#34;, the steepening of the cosmic ray spectrum at energy $E \gsim 10^{15.5}$ eV, is due to &#34;new physics&#34;, namely new interactions at TeV cm energies which produce particles undetected by the experimental apparatus. In this letter we examine specifically the possibility that this interaction is

M. Czakon, J. Gluza, M. Zralek

In the standard approach to the neutrino oscillations a unitary relation among weak and mass eigenstates of light neutrinos is imposed. However, in many extensions of the SM left-handed, active neutrinos mix with additional heavy neutrino states. Consequences of this additional mixing, driven by experimental constraints, on the neutrino oscillations are cons

Takahiro MIURA, Minoru TANAKA

We study the exclusive semi-tauonic B decay, $\bar B \to D τ\barν_τ$, in two-Higgs-doublet models. Using recent experimental and theoretical results on hadronic form factors, we estimate theoretical uncertainties in the branching ratio. As a result, we clarify the potential sensitivity of this mode to the charged Higgs exchange. Our analysis will help to pro

M. Beneke

I discuss three B physics results with potential for exhibiting new flavour-changing interactions: (1) the time-dependent CP asymmetry in B\to J/ψK_S decay; (2) branching fractions and CP asymmetries in B\to ππ, πK decays; (3) inclusive and exclusive semi-hadronic b\to s transitions.

M. C. Ruivo, P. F. Costa, C. A. Sousa

The behavior of kaons and pions in hot non strange quark matter, simulating neutron matter, is investigated within the SU(3) Nambu-Jona-Lasinio [NJL] and in the Enlarged Nambu-Jona-Lasinio [ENJL] (including vector pseudo-vector interaction) models. At zero temperature, it is found that in the NJL model, where the phase transition is first order, low energy m

Paolo Cea, Leonardo Cosmai

We study vacuum dynamics of SU(3) lattice gauge theory at finite temperature. Using the lattice Schrödinger functional, SU(3) vacuum is probed by means of an external constant Abelian chromomagnetic field. Our preliminary numerical data suggest that, by increasing the strength of the applied external field, deconfinement temperature decreases towards zero. T

S. Hands, I. Montvay, L. Scorzato, J. Skullerud

We study SU(2) lattice gauge theory at non-zero chemical potential with one staggered quark flavor in the adjoint representation. In this model the fermion determinant, although real, can be both positive and negative. We have performed numerical simulations using both hybrid Monte Carlo and two-step multibosonic algorithms, the latter being capable of explo

BES Collaboration

Radiative decays of the radially excited charmonium resonance, ψ(2S), into ππ, K Kbar and ηηfinal states have been measured in a sample of 3.96 * 10^6 ψ(2S) events collected by the BES collaboration. The branching ratios B(ψ(2S) -> γf_{2}(1270)) = (2.27 +- 0.26 +- 0.39) * 10^{-4} and B(ψ(2S) -> γf_0(1710)) * B(f_0(1710) -> K^+ K^-) = (5.59 +- 1.12 +- 0.93) *

Y. Bisabr, H. Salehi

A mechanism is introduced to reduce a large cosmological constant to a sufficiently small value consistent with observational upper limit. The basic ingradient in this mechanism is a distinction which has been made between the two unit systems used on cosmology and particle physics. We have used a conformal invariant gravitational model to define a particula

Gaurav Sharma, H. Joel Trussell

This paper surveys current technology and research in the area of digital color imaging. In order to establish the background and lay down terminology, fundamental concepts of color perception and measurement are first presented us-ing vector-space notation and terminology. Present-day color recording and reproduction systems are reviewed along with the comm

Dan L. Burk, Mark A. Lemley

Although patent law purports to cover all manner of technologies, we have noticed recent divergence in the standards applied to biotechnology and to software patents: the Federal Circuit has applied a very permissive standard of obviousness in biotechnology, but a highly restrictive disclosure requirement. The opposite holds true for software patents, which

A. Michael Noll

The popular conception is that data traffic nearly, if not already, exceeds voice traffic on backbone networks. However, the results of research reported in this paper imply that voice traffic greatly exceeds data traffic when real users are asked to estimate their usage of a wide variety of media. Media usage was surveyed for students in New York City and i

Luis C. O. Dacal, Jose A. Brum

We present here the results of calculations of the negative trion binding energy in the presence of an electron gas. The screening of the Coulomb interaction and the Pauli exclusion principle are considered. Our results show a rapid ionization of the negative trion due to the Pauli exclusion principle while the screening is mainly responsible for the weakeni

Jian-Xin Zhu, C. S. Ting, A. V. Balatsky

The local quasiparticle spectra around the vortex core of a d-wave superconductor in the mixed state is studied by solving the lattice Bogoliubov-de Gennes equations self-consistently. It is shown that in addition to the zero-energy states, there also exist core states of high angular momentum. A nonmagnetic unitary impurity sitting at the core center is non

Luis C. O. Dacal, R. Ferreira, G. Bastard, Jose A. Brum

We present a model to take into account the interface defects contribution on the binding energy of charged exciton in GaAs/Al$_{0.3}$Ga$_{0.7}$As quantum wells. The dependence of the binding energy gain and of the trion size on the quantum well width are variationally calculated. We show that the trion is more sensitive to interface defects than the exciton

Y. Y. Xue, D. H. Cao, B. Lorenz, C. W. Chu

An unusual thermal-magnetic hysteresis was observed between a minor magnetic transition around 120 K and the main one at 80 K in superconducting RuSr2(R,Ce)2Cu2O10-delta (Ru1222R) samples, where R = Gd or Eu, down to a submicron length-scale. The observation suggests a possible phase-separation and is consistent with the very small but universal demagnetizin

N. Stefanakis

We calculate the tunneling conductance spectra of a normal metal / insulator / triplet superconductor from the reflection amplitudes using the Blonder-Tinkham-Klapwijk (BTK) formula. For the triplet superconductor we assume one special p-wave order parameter having line nodes and two two dimensional $f$-wave order parameters with line nodes breaking the time

Jae Yoo, Akira Yamaguchi, Motohiro Nakano, J. Krzystek

The preparations, X-ray structures, and detailed physical characterizations are presented for two new mixed-valence tetranuclear manganese complexes that function as single-molecule magnets (SMM&#39;s): [Mn4(hmp)6Br2(H2O)2]Br2.4H2O and [Mn4(6-me-hmp)6Cl4].4H2O, where hmp- is the anion of 2-hydroxymethylpyridine and 6-me-hmp- is the anion of 6-methyl-2-hydrox

Yoram Louzoun, Sorin Solomon

The Generalized Lotka Voltera (GLV) formalism has been introduced in order to explain the power law distributions in the individual wealth (w_i (t)) (Pareto law) and financial markets returns (fluctuations) (r) as a result of the auto-catalytic (multiplicative random) character of the individual capital dynamics. As long as the multiplicative random factor (

Karsten Reuter, M. Veronica Ganduglia-Pirovano, Catherine Stampfl, Matthias Scheffler

Using density-functional theory, we predict that the oxidation of the Ru(0001) surface proceeds via the accumulation of sub-surface oxygen in two-dimensional islands between the first and second substrate layer. This leads locally to a decoupling of an O-Ru-O trilayer from the underlying metal. Continued oxidation results in the formation and stacking of mor

E. Cimpoiasu, G. A. Levin, C. C. Almasan, A. P. Paulikas

We report magnetoresistivity measurements on strongly underdoped YBa_2Cu_3O_x (x=6.25, 6.36) single crystals in applied magnetic fields H || c-axis. We identify two different contributions to both in-plane and out-of-plane magnetoresistivities. The first contribution has the same sign as the temperature coefficient of the resistivity \partial ln(ρ_i)/\partia

Argyrios Tsolakidis, Daniel Sanchez-Portal, Richard M. Martin

We report on a general method for the calculation of the frequency-dependent optical response of clusters based upon time-dependent density functional theory (TDDFT). The implementation is done using explicit propagation in the time domain and a self-consistent program that uses a linear combination of atomic orbitals (LCAO). Our actual calculations employ t

B. I. Ivlev

Two interaction mechanisms of particles in a fluid are proposed on base of forces, mediated by hydrodynamic thermal fluctuations. The first one is similar to the conventional van der Waals interaction, but instead of been mediated by electromagnetic fluctuations, it is mediated by fluctuations of hydrodynamic sound waves. The second one is due to a thermal d

Eugene V. Colla, Lambert K. Chao, M. B. Weissman

Barkhausen noise, including both periodic and aperiodic components, is found in and near the relaxor regime of a familiar relaxor ferroelectric, PbMg$_{1/3}$Nb$_{2/3}$O$_3$, driven by a periodic electric field. The temperature dependences of both the amplitude and spectral form show that the size of the coherent dipole moment changes shrink as the relaxor re

Ronald Blaak, David Dubbeldam

We have constructed a regular binary thermal lattice-gas in which the thermal diffusion and mass diffusion are coupled and form two nonpropagating diffusive modes. The power spectrum is shown to be similar in structure as for the one in real fluids, in which the central peak becomes a combination of coupled entropy and concentration contributions. Our theore

L. S. Schulman, E. Mihokova, A. Scardicchio, P. Facchi

Millisecond crystal relaxation has been used to explain anomalous decay in doped alkali halides. We attribute this slowness to Fermi-Pasta-Ulam solitons. Our model exhibits confinement of mechanical energy released by excitation. Extending the model to long times is justified by its relation to solitons, excitations previously proposed to occur in alkali hal

Wira B. Nurdin, Klaus-Dieter Schotte

In this micro-canonical simulation the temperature and also the specific heat are determined as averages of expressions easy to implement. The XY-chain is studied for a test. The second order transition on a cubic lattice and the first order transition on an fcc lattice are analyzed in greater detail to have a more severe test about the feasibility of this m

C. Ferdeghini, V. Ferrando, G. Grassano, W. Ramadan

The electronic anisotropy in MgB2, which arises from its layered crystal structure is not completely clear until now. High quality c-oriented films offer the opportunity of studying such property. MgB2 thin films were deposited by using two methods both based on room temperature precursor deposition (by Pulsed Laser Ablation) and ex-situ annealing in Mg atmo

M. C. Gordillo, J. Boronat, J. Casulleras

We present diffusion Monte Carlo calculations of D$_2$ adsorbed inside a narrow carbon nanotube. The 1D D$_2$ equation of state is reported, and the one-dimensional character of the adsorbed D$_2$ is analyzed. The isotopic dependence of the constitutive properties of the quantum fluid are studied by comparing D$_2$ and H$_2$. Quantum effects due to their dif

Pavol Farkasovsky

The density matrix renormalization group method is used to examine possibilities of electronic ferroelectricity in the spinless Falicov-Kimball model. The model is studied for a wide range of parameters including weak and strong interactions as well as the symmetric and unsymmetric case. In all examined cases the $<d^{+}f>$-expectation value vanishes for van

Todor Mishonov, Nicolas Chéenne, Didier Robbes, Joseph Indekeu

The generation of harmonics of the voltage response is considered when an AC current is applied through a superconducting film above T_c. It is shown that almost at all temperatures the mechanism of the temperature oscillations created by the AC current and the temperature dependence of the resistance dominates over the isothermal nonlinear electric conducti

M. Roberts, Y. C. Chung, S. Lyapin, N. J. Mason

We have measured the current-voltage (I-V) of type II InAs/GaSb/InAs double heterojunctions (DHETs) with &#39;GaAs like&#39; interface bonding and GaSb thickness between 0-1200 Å. A negative differential resistance (NDR) is observed for all DHETs with GaSb thickness $>$ 60 Åbelow which a dramatic change in the shape of the I-V and a marked hysteresis is obse

H. J. Lewandowski, D. M. Harber, D. L. Whitaker, E. A. Cornell

We observe counter-intuitive spin segregation in an inhomogeneous sample of ultra-cold, non-condensed Rubidium atoms in a magnetic trap. We use spatially selective microwave spectroscopy to verify a model that accounts for the differential forces on two internal spin states. In any simple understanding of the cloud dynamics, the forces are far too small to a

I. R. Shein, A. L. Ivanovskii

The band structure and the Fermi surface of hexagonal diborides ZrB2, VB2, NbB2, TaB2 have been studied by the self-consistent full-potential LMTO method and compared with those for the isostructural superconductor MgB2. Factors responsible for the superconducting properties of AlB2-like diborides are analyzed, and the results obtained are compared with prev

Cristina Buzea, Tsutomu Yamashita

This review paper illustrates the main normal and superconducting state properties of magnesium diboride, a material known since early 1950&#39;s, but recently discovered to be superconductive at a remarkably high critical temperature Tc=40K for a binary compound. What makes MgB2 so special? Its high Tc, simple crystal structure, large coherence lengths, hig

Ya. V. Fominov, N. M. Chtchelkatchev, A. A. Golubov

Superconductor/ferromagnet bilayers are known to exhibit nontrivial dependence of the critical temperature T_c on the thickness d_f of the ferromagnetic layer. We develop a general method for investigation of T_c as a function of the bilayer&#39;s parameters. It is shown that interference of quasiparticles makes T_c(d_f) a nonmonotonic function. The results

M. S. Brotherton, R. F. Green, G. A. Kriss, W. Oegerle

We present far-ultraviolet spectra of the Seyfert 1.5 galaxy NGC 5548 obtained in 2000 June with the Far Ultraviolet Spectroscopic Explorer (FUSE). Our data span the observed wavelength range 915--1185 Angstroms at a resolution of 20 km/s. The spectrum shows a weak continuum and emission from O VI, C III, and He II. The FUSE data were obtained when the AGN w

Bradley M. Peterson

Continuum and emission-line variability of active galactic nuclei provides a powerful probe of microarcsecond scale structures in the central regions of these sources. In this contribution, we review basic concepts and methodologies used in analyzing AGN variability. We develop from first principles the basics of reverberation mapping, and pay special attent

Peter L. Gonthier, Michelle S. Ouellette, Joel Berrier, Shawn O&#39;Brien

We simulate the characteristics of the Galactic population of radio and $γ$-ray pulsars using Monte Carlo techniques. At birth, neutron stars are spatially distributed in the Galactic disk, with supernova-kick velocities, and randomly dispersed in age back to $10^9$ years. They are evolved in the Galactic gravitational potential to the present time. From a r

Neil M. Nagar, Andrew S. Wilson, Heino Falcke

We present simultaneous, sub-arcsecond (<=50pc) resolution 5 GHz, 8.4 GHz, and 15 GHz VLA observations of a well-defined sample of sixteen low-luminosity active galactic nuclei (LLAGNs). The radio emission in most of these nuclei does not show the rising spectrum (0.2 <= s <= 1.3, L_nu propto nu^{s}) expected from thermal electrons in an advection dominated

S. R. Majewski, A. D. Forestell, J. C. Ostheimer, C. Palma

We are exploring the extended stellar distributions of Galactic satellite galaxies and globular clusters. For seven objects studied thus far, the observed profile departs from a King function at large r, revealing a ``break population&#39;&#39; of stars. In our sample, the relative density of the ``break&#39;&#39; correlates to the inferred M/L of these obje

D. Queloz, G. W. Henry, J. P. Sivan, S. L. Baliunas

The G0V star HD166435 has been observed by the fiber-fed spectrograph ELODIE as one of the targets in the large extra-solar planet survey that we are conducting at the Observatory of Haute-Provence. We detected coherent, low-amplitude, radial-velocity variations with a period of 3.7987days, suggesting a possible close-in planetary companion. Subsequently, we

J. Poirier, C. D&#39;Andrea

Project GRAND is an array of proportional wire chambers composed of 64 stations with each station containing eight proportional wire planes and a 50 mm steel plate. The proportional wire planes together with the steel absorber allow a measurement of the angle and identity of single muon tracks. Of the two data-taking triggers, one is for single tracks. Since

J. Poirier, D. Baker, J. Barchie, C. D&#39;Andrea

Project GRAND is an extensive air shower array of proportional wire chambers. It has 64 stations in a 100m x 100m area; each station has eight planes of proportional wire chambers with a 50 mm steel absorber plate above the bottom two planes. This arrangement of planes, each 1.25 square meters of area, allow an angular measurement for each track to 0.25 degr

David A. Smith, Andrew S. Wilson, Keith A. Arnaud, Yuichi Terashima

The results from a recent Chandra ACIS-S study of the cluster surrounding Cygnus A are presented. We have deprojected the X-ray spectra taken from various elliptical shells in order to derive the run of temperature, density, pressure, and abundance for the ICM as a function of radius. We confirm a drop in temperature of the X-ray emitting gas from $\sim 8$ k

D. R. Gies, M. V. McSwain, R. L. Riddle, Z. Wang

We present results from new optical and UV spectroscopy of the unusual binary system SS 433, and we discuss the relationship of the particular spectral components we observe to the properties of the binary. (1) The continuum spectrum which we associate with flux from the super-Eddington accretion disk and the dense part of its wind. (2) H-alpha moving compon

J. -M. Miralles, H. Haemmerle, N. Pirzkal, P. Schneider

In June 1997, parallel observations using the Space Telescope Imaging Spectrograph (STIS) on the HST started to be taken in substantial numbers along many different lines-of-sight. We are using the imaging data to investigate the distortion of background galaxies by the gravitational field of the large scale matter distribution, also known as Cosmic Shear. T

Tracy L. Smith, Adolf N. Witt

Interstellar dust contains a component which reveals its presence by emitting a broad, unstructured band of light in the 540 to 950 nm wavelength range, referred to as Extended Red Emission (ERE). The presence of interstellar dust and ultraviolet photons are two necessary conditions for ERE to occur. This is the basis for suggestions which attribute ERE to a

J. Poirier, C. D&#39;Andrea, M. Dunford

The Ground-Level Event (GLE) associated with the X5.7 solar flare of July 14, 2000 is studied by the Project GRAND proportional wire chamber array. Results are compared to those obtained by the Climax Neutron Monitor experiment which detects secondary neutrons. The Climax monitor, located in Climax, Colorado, is operated by the University of Chicago. The tim

P. C. van der Kruit

One the most cited papers in astronomy is Ken Freeman&#39;s 1970 paper on exponential disks in galaxies. In this contribution I review what has been done in this area since then and what we can infer about systematic properties of disks in galaxies from surface photometry, HI synthesis observations and measurements of stellar kinematics. Most disks have radi

Mallory S. E. Roberts, Roger W. Romani, Simon Johnston

We present X-ray, radio, and infrared observations of the 68 ms pulsar PSR J1420-6048 and its surrounding nebula, a possible counterpart of the gamma-ray source GeV J1417-6100/3EG J1420-6038. Pulsed X-ray emission at the radio period is marginally detected by ASCA from a source embedded in the hard spectrum X-ray nebula AX J1420.1-6049. At radio wavelengths,