August 1999 arXiv papers — page 14

Ivan A. Larkin, L. S. Levitov

The incompressible Quantum Hall strip is sensitive to charging of localized states in the cyclotron gap. We study the effect of localized states by a density functional approach and find electron density and the strip width as a function of the density of states in the gap. Another important effect is electron exchange. By using a model density functional wh

R. K. Koleva, A. Widom, D. Garelick, Meredith Harris

Kinematic measurements of two simultaneous coordinates from postural sway during quiet standing were performed employing multiple ultrasonic transducers. The use of accurate acoustic devices was required for the detection of the small random noise displacements. The trajectory in the anteroposterior - mediolateral plane of human chest was measured and compar

Shan-Wen Tsai, J. B. Marston

We use the density-matrix renormalization-group (DMRG) algorithm and finite-size scaling to study a supersymmetric (SUSY) spin chain that models plateau transitions in the integer quantum Hall effect. To illustrate the method, we first present results for the S=1 antiferromagnetic spin chain. Different scaling behavior of the dimerization operator is obtaine

A. Rubio-Ponce, R. Baquero

We have reproduced band structure calculations from the literature and have used them to analyze in detail the energy landscape around the Fermi level. We found three Van Hove singularities, two below (-230, -54 meV) and one above the Fermi level (+27 meV). We have studied the composition of each one of them and found that states comming from the chain do co

K. L. Sebastian

We argue that the recent experiments of Kelly et. al.(Angew. Chem. Int. Ed. Engl. 36, 1866 (1997)) on molecular ratchets, in addition to being in agreement with the second law of thermodynamics, is a test of the principle of detailed balance for the ratchet. We suggest new experiments, using an asymmetric ratchet, to further test the principle. We also point

F. Weig, W. Zwerger

We study the detection of a BCS transition within a sample of Lithium--6 atoms confined in a harmonic trap. Using the local density approximation we calculate the pair correlation function in the normal and superfluid state at zero temperature. We show that the softening of the Fermi hole associated with a BCS transition leads to an observable increase in th

Werner Hanke, Marc G. Zacher, Enrico Arrigoni, Shou-Cheng Zhang

Recent angle resolved photoemission (ARPES) data, which found evidence for a d-wave-like modulation of the antiferromagnetic gap, suggest an intimate interrelation between the antiferromagnetic insulator and the superconductor with its d-wave gap. This poses a new challenge to microscopic descriptions, which should account for this correlation between, at fi

O. Zobay, B. M. Garraway

The influence of atomic interactions on time-dependent tunneling processes of Bose-Einstein condensates is investigated. In a variety of contexts the relevant condensate dynamics can be described by a Landau-Zener equation modified by the appearance of nonlinear contributions. Based on this equation it is discussed how the interactions modify the tunneling p

Anita Mehta, J. M. Luck

We present two models of competitive learning, which are respectively interfacial and cooperative learning. This learning is outcome-related, so that spatially and temporally local environments influence the conversion of a given site between one of two different types. We focus here on the behavior of the models at coexistence, which yields new critical beh

Mai Suan Li, Marek Cieplak

We propose two approaches for determining the native basins in off-lattice models of proteins. The first of them is based on exploring the saddle points on selected trajectories emerging from the native state. In the second approach, the basin size can be determined by monitoring random distortions in the shape of the protein around the native state. Both te

Mai Suan Li, Marek Cieplak

Model off-lattice sequences in two dimensions are constructed so that their native states are close to an on-lattice target. The Hamiltonian involves the Lennard-Jones and harmonic interactions. The native states of these sequences are determined with a high degree of certainty through Monte Carlo processes. The sequences are characterized thermodynamically

Sandeep K. Joshi, A. M. Jayannavar

We have studied the reflection delay time distribution from a one-dimensional electronically random system of finite length. We show that the average delay time is a non-monotonic function of the strength of the disorder and exhibits three qualitatively different regimes. In the weak disorder limit the scattering is dominated by the ordinary Born scattering.

Yuri S. Kivshar, Tristram J. Alexander, Sergey K. Turitsyn

We consider the Bose-Einstein condensate in a parabolic trap as a macroscopic quantum oscillator and describe, analytically and numerically, its collective modes - a nonlinear generalisation of the (symmetric and antisymmetric) Hermite-Gauss eigenmodes of a harmonic quantum oscillator.

N. F. Rulkov, M. M. Sushchik, L. S. Tsimring, A. R. Volkovskii

Utilization of chaotic signals for covert communications remains a very promising practical application. Multiple studies indicated that the major shortcoming of recently proposed chaos-based communication schemes is their susceptibility to noise and distortions in communication channels. In this talk we discuss a new approach to communication with chaotic s

Eyal Maoz, Jeffrey A. Newman, Laura Ferrarese, Peter B. Stetson

Distances measured using Cepheid variable stars have been essential for establishing the cosmological distance scale and the value of the Hubble constant. These stars have remained the primary extragalactic distance indicator since 1929 because of the small observed scatter in the relationship between their pulsation period and luminosity, their large number

T. W. Giblin, J. van Paradijs, C. Kouveliotou, V. Connaughton

In this Letter, we present the first evidence in the BATSE data for a prompt high-energy (25-300 keV) afterglow component from a gamma-ray burst (GRB), GRB980923. The event consists of rapid variabilty lasting ~40 s followed by a smooth power law emission tail lasting ~400 s. An abrupt change in spectral shape is found when the tail becomes noticeable. Our a

J. B. Hutchings, D. M. Crenshaw, A. C. Danks, T. R. Gull

Narrow-band imaging of the nuclear region of NGC 4151 with the Hubble Space Telescope is presented. The filter bandpasses isolate line emission in various high velocity ranges in several ions. Slitless and long-slit spectra of the region with the Space Telescope Imaging Spectrograph also indicate the locations of high velocity gas. These emission regions are

K. A. Postnov, M. E. Prokhorov, V. M. Lipunov

We show that the distribution of observed energies of GRB with known redshifts can be explained by the hypothesis of the standard energy release E_0=5 10^51 ergs. Two situations are possible, either the beaming angle differs from burst to burst, or there is a universal emssion diagram in each burst, the observed difference being due to different viewing angl

V. V. Vassiliev, D. A. Carter-Lewis, A. M. Hillas, M. P. Kertzman

VERITAS is a proposed major ground-based gamma-ray observatory to be built at the Whipple Observatory in southern Arizona, USA. It will consist of an array of seven 10m imaging Cherenkov telescopes designed to conduct gamma-ray observations in the energy range of 50 GeV - 50 TeV. A description of the baseline VERITAS design and optimization criteria are pres

A. Dobrzycki, D. Engels, H. -J. Hagen

During the course of Hamburg/CfA Bright Quasar Survey we discovered a bright (B=15.9), high redshift (z=2.51) quasar HS 1603+3820. The quasar has a rich complex of CIV absorbers, containing at least five systems, all within 3000 km/s from one another. Despite large ejection velocity (v(ej)>5000 km/s for all components) the complex is likely to be associated

David H. Weinberg, Romeel Dave', Jeffrey P. Gardner, Lars Hernquist

We review theoretical approaches to the study of galaxy formation, with emphasis on the role of hydrodynamic simulations in modeling the high redshift galaxy population. We present new predictions for the abundance of star-forming galaxies in the Lambda + cold dark matter model (Omega_m=0.4, Omega_L=0.6), combining results from several simulations to probe a

Klaus Strobel, Christoph Schaab, Manfred K. Weigel

Properties of non-rotating and rapidly rotating protoneutron stars and neutron stars are investigated. Protoneutron stars are hot, lepton rich neutron stars which are formed in Type-II supernovae. The hot dense matter is described by a realistic equation of state which is obtained by extending a recent approach of Myers and Swiatecki to the nuclear mass form

Sabine Schindler

We investigate the evolution of clusters of galaxies in a sample of distant clusters with redshifts between 0.3 and 1.0. We show the abilities and limitations of combined ROSAT and ASCA data to draw cosmological conclusions. For the first time bolometric luminosities, masses, gas masses, gas mass fractions, and iron masses are derived in such a distant sampl

Thorsten Naab, Andreas Burkert, Lars Hernquist

The origin of boxy and disky elliptical galaxies is investigated. The results of two collisionless N-body simulations of spiral-spiral mergers with mass ratios of 1:1 and 3:1 are discussed and the projected properties of the merger remnants are investigated. It is shown that the equal-mass merger leads to an anisotropic, slowly rotating system with preferent

Yoshihiro Ueda, Tadayuki Takahashi, Yoshitaka Ishisaki, Takaya Ohashi

We present first results from the ASCA Medium Sensitivity Survey (AMSS; or the GIS catalog project). From the serendipitous fields amounting to 106 degE-2, we determined the Log N - Log S relations in the 0.7-7 keV and 2-10 keV bands with the best statistical accuracy obtained so far, over the flux range from 1 x 10E-11 to 5 x 10E-14 and 7 x 10E-14 erg sE-1

Andrei V. Frolov, Arne L. Larsen

We consider scattering and capture of circular cosmic strings by a Schwarzschild black hole. Although being a priori a very simple axially symmetric two-body problem, it shows all the features of chaotic scattering. In particular, it contains a fractal set of unstable periodic solutions; a so-called strange repellor. We study the different types of trajector

P. Meszaros, M. J. Rees

The role of a photospheric component and of pair breakdown is examined in the internal shock model of gamma-ray bursts. We discuss some of the mechanisms by which they would produce anomalously steep low energy slopes, X-ray excesses and preferred energy breaks. Sub-relativistic comptonization should dominate in high comoving luminosity bursts with high bary

M. Brhlik, L. Everett, G. L. Kane, J. Lykken

We investigate the possibility of large CP- violating phases in the soft breaking terms derived in superstring models. The bounds on the electric dipole moments (EDM's) of the electron and neutron are satisfied through cancellations occuring because of the structure of the string models. Three general classes of four-dimensional string models are conside

Richard Altendorfer, Jonathan Bagger

The partial breaking of supersymmetry in anti-de Sitter (AdS) space can be accomplished using two of four dual representations for the massive OSp(1,4) spin-3/2 multiplet. The representations can be ``unHiggsed,'' which gives rise to a set of dual N=2 supergravities and supersymmetry algebras.

Marc Garbey, Hans G. Kaper

This article addresses some asymptotic and numerical issues related to the solution of Burgers' equation, $-\epsilon u_{xx} + u_t + u u_x = 0$ on $(-1,1)$, subject to the boundary conditions $u(-1) = 1 + \delta$, $u(1) = -1$, and its generalization to two dimensions, $-\epsilon \Delta u + u_t + u u_x + u u_y = 0$ on $(-1,1) \times (-\pi, \pi)$, subject to th

A. Yamilov, L. I. Deych, A. A. Lisyansky

A detailed analytical study of an impurity induced polariton band arising inside a spectral gap between lower and upper polariton branches is presented. Using the microcanonical method, we calculate the density of states and localization length of the impurity polaritons. Analytical results are compared with numerical simulations and excellent agreement is f

Ulf Lindstrom, Martin Rocek, Rikard von Unge

We develop a graphical representation of polynomial invariants of unitary gauge groups, and use it to find the algebraic curve corresponding to a hyperkahler quotient of a linear space. We apply this method to four dimensional ALE spaces, and for the A_k, D_k, and E_6 cases, derive the explicit relation between the deformations of the curves away from the or

Aristophanes Dimakis, Folkert Muller-Hoissen

The existence of an infinite set of conserved currents in completely integrable classical models, including chiral and Toda models as well as the KP and self-dual Yang-Mills equations, is traced back to a simple construction of an infinite chain of closed (respectively, covariantly constant) 1-forms in a (gauged) bi-differential calculus. The latter consists

Yang Sun, Kenji Hara, Javid A. Sheikh, Jorge G. Hirsch

We present a fully quantum-mechanical, microscopic, unified treatment of ground-state band and multi-phonon $γ$-vibrational bands using shell model diagonalization with the triaxial projected shell model. The results agree very well with data on the g- and $γ$-band spectra in $^{156-170}$Er, as well as with recently measured $4^+$ 2-phonon $γ$-bandhead energ

Jens O. Andersen, Eric Braaten, Michael Strickland

The quark contribution to the free energy of a hot quark-gluon plasma is calculated to leading order in hard-thermal-loop (HTL) perturbation theory. This method selectively resums higher order corrections associated with plasma effects, such as screening, quasiparticles, and Landau damping. Comparing to the weak-coupling expansion of QCD, the error in the on

Kamiokande Collaboration

A total of 137 upward stopping muons of minimum energy 1.6 GeV are observed by Super-Kamiokande during 516 detector live days. The measured muon flux is 0.39+/-0.04(stat.)+/-0.02(syst.)x10^{-13}cm^{-2}s^{-1}sr^{-1} compared to an expected flux of 0.73+/-0.16(theo.)x10^{-13}cm^{-2}s^{-1}sr^{-1}. Using our previously-published measurement of the upward through

Bosiljka Tadić

We study Barkhausen noise in a diluted two-dimensional Ising model with the extended domain wall and weak random fields occurring due to coarse graining. We report two types of scaling behavior corresponding to (a) low disorder regime where a single domain wall slips through a series of positions when the external field is increased, and (b) large disorder r

Yoshio Torii, Yoichi Suzuki, Mikio Kozuma, Takahiro Kuga

We construct a Mach-Zehnder interferometer using Bose-Einstein condensed rubidium atoms and optical Bragg diffraction. In contrast to interferometers based on normal diffraction, where only a small percentage of the atoms contribute to the signal, our Bragg diffraction interferometer uses all the condensate atoms. The condensate coherence properties and high

Eric A. Galapon

In single Hilbert space, Pauli's well-known theorem implies that the existence of a self-adjoint time operator canonically conjugate to a given Hamiltonian signifies that the time operator and the Hamiltonian possess completely continuous spectra spanning the entire real line. Thus the conclusion that there exists no self-adjoint time operator conjugate

B. Ram

We give a method in which a quantum of mass equal to twice the Planck mass arises naturally. Then using Bose-Einstein statistics we derive an expression for the black hole entropy which physically tends to the Bekenstein-Hawking formula.

Takayuki Tsuchida, Miki Wadati

We study matrix generalizations of derivative nonlinear Schrödinger-type equations, which were shown by Olver and Sokolov to possess a higher symmetry. We prove that two of them are `C-integrable' and the rest of them are `S-integrable' in Calogero's terminology.

Ari Mizel, M. W. Mitchell, Marvin L. Cohen

We formulate a novel ground state quantum computation approach that requires no unitary evolution of qubits in time: the qubits are fixed in stationary states of the Hamiltonian. This formulation supplies a completely time-independent approach to realizing quantum computers. We give a concrete suggestion for a ground state quantum computer involving linked q

H. Moya-Cessa, J. A. Roversi, S. M. Dutra, A. Vidiella-Barranco

We present a feasible scheme for reconstructing the quantum state of a field prepared inside a lossy cavity. Quantum coherences are normally destroyed by dissipation, but we show that at zero temperature we are able to retrieve enough information about the initial state, making possible to recover its Wigner function as well as other quasiprobabilities. We p

Maider Machado, Pablo Ordejon, Emilio Artacho, Daniel Sanchez-Portal

We present a systematic Density Functional Theory (DFT) study of geometries and energies of the nucleic acid DNA bases (guanine, adenine, cytosine and thymine) and 30 different DNA base-pairs. We use a recently developed linear-scaling DFT scheme, which is specially suited for systems with large numbers of atoms. As a first step towards the study of large DN

I. R. Barabanov, V. I. Beresnev, V. N. Kornoukhov, E. A. Yanovich

Rare-earth (Yb/Gd) complexes with neutral organophosphorus ligands are briefly discussed for their application in liquid scintillation technique. To evaluate the principle feasibility of a high rare-earth loaded scintillator, the ytterbium chloride complexes with tri-isoamylphosphine oxides were synthesized. Relative scintillation efficiency (RSE) for two Yb

S. I. Betelu, D. G. Aronson, S. B. Angenent

In the focusing problem we study a solution of the porous medium equation $u_t=Δ(u^m)$ whose initial distribution is positive in the exterior of a closed non-circular two dimensional region, and zero inside. We implement a numerical scheme that renormalizes the solution each time that the average size of the empty region reduces by a half. The initial condit

Mikhail V. Khenner, Dmitrii V. Lyubimov

We consider longwave mode of the interface instability in the system comprising of two immiscible fluid layers. The fluids fill out plane horizontal cavity which is subjected to horizontal harmonic vibration. The analysis is performed within the framework of "high frequency of the vibration" approximation and the averaging procedure. The nonlinear eq

J. Meng, N. Takigawa

The structure of superheavy elements newly discovered in the $^{208}$Pb($^{86}$Kr,n) reaction at Berkeley is systematically studied in the Relativistic Mean Field (RMF) approach. It is shown that various usually employed RMF forces, which give fair description of normal stable nuclei, give quite different predictions for superheavy elements. Among the effect

G. A. Miller

The process $π+ A$ leading to a pair of mini-jets at high relative transverse momentum ($k_t \gsim 2$ GeV) while leaving the nucleus in its ground state was selected as a definitive test of the existence of color transparency by Frankfurt, Miller and Strikman in 1993. The preliminary results of Fermilab experiment E791, led by Ashery and Weiss-Babai, show a

Gilles Pisier

Let F(X) denote the norm closure of the space of all finite rank operators on a Banach space X. We show that there are Banach spaces X for which the product map $a\otimes b\to ab$ does not define a surjective map from the projective tensor product $F(X) \hat\otimes F(X)$ onto F(X).

Do Ngoc Diep, Nguyen Viet Hai

We construct start-products on the co-adjoint orbit of Lie group $\Aff({\bf C})$ of affine transformations of the complex straight line and apply them to obtain the irreducible unitary representations of this group. These results show effectiveness of the Fedosov quantization even for groups which are neither nilpotent nor exponential. Together with the resu

Terasoma, Tomohide

In this paper, we show that the coefficient of the Taylor expansion of Selberg integrals with respect to exponent variables are expressed as a linear combination of multiple zeta values. We use beta-nbc base so that the Selberg integral is holomorphic with respect to the exponent variables.

Travis Schedler

In the 1980's, Belavin and Drinfeld classified solutions r of the classical Yang-Baxter equation (CYBE) for simple Lie algebras \mathfrak g satisfying 0 \neq r + r_{21} \in (S^2 \mathfrak{g})^{\mathfrak{g}}. They proved that all such solutions fall into finitely many continuous families and introduced combinatorial objects to label these families, Belavi

Alexandre A. Panin

We describe here the lower garland of some lattices of intermediate subgroups in linear groups. The results are applied to the case of subgroup lattices in general and special linear groups over a class of rings, containing the group of rational points T of a maximal non-split torus in the corresponding algebraic group. It turns out that these garlands coinc

Alexandre A. Panin

We construct Galois theory for sublattices of certain complete modular lattices and their automorphism groups. A well-known description of the intermediate subgroups of the general linear group over a semilocal ring containing the group of diagonal matrices, due to Z.I.Borewicz and N.A.Vavilov, can be obtained as a consequence of this theory.

Markus A. Luty, Riccardo Rattazzi

We give a self-contained discussion of recent progress in computing the non-perturbative effects of small non-holomorphic soft supersymmetry breaking, including a simple new derivation of these results based on an anomaly-free gauged U(1)_R background. We apply these results to N = 1 theories with deformed moduli spaces and conformal fixed points. In an SU(2

Yoshitaka Okumura

We present the general method to introduce the generalized Chern-Simons form and the descent equation which contain the scalar field in addition to the gauge fields. It is based on the technique in a noncommutative differential geometry (NCG) which extends the $N$-dimensional Minkowski space $M_N$ to the discrete space such as $M_N\times Z_2$ with two point

N. Tanimura

The chiral symmetry breaking in the 4-dimensional QED with the chirally invariant four-fermion interaction is discussed by using a novel path integral expression in terms of the field-strength tensor. In the local potential approximation, we find that the chiral symmetry is spontaneously broken for any nonzero gauge and four-fermion couplings on the tree lev

Marcia J. King

A relativistic quantized particle model avoids difficulties through (1) a Hamiltonian undecomposable into H=H(0)+H(I), (2) a separation of the evolution parameter s from dynamics, (3) "leptons" and "hadrons" composed of "quarks," and (4) the absence of background reference frames. The stringlike Lagrangian is L=-{-[F(Q)]2 [dQ/ds]2+[Fd

Amir H. Fariborz

In this talk, an overview of the status of the light scalar mesons in the context of the non linear chiral Lagrangian of references [1-3] is presented. The evidence for the existence of a scalar nonet below 1 GeV is reviewed, and it is shown that by introducing a scalar nonet an indirect way of probing the quark substructure of these scalars through the scal

Hsin-Chia Cheng, Konstantin T. Matchev

In a realistic theory with large extra dimensions and TeV scale gravity, there are often other particles living in the extra dimensions in addition to gravitons. A well motivated candidate is the flavon in a flavor theory which explains the smallness of the fermion masses by the large volume of the extra dimensions. The flavon interactions involve the Higgs

Jonathan A. Bagger, Adam F. Falk, Morris Swartz

We compute the bounds from precision observables on alternative theories of electroweak symmetry breaking. We show that a cut-off as large as 3 TeV can be accomodated by the present data, without unnatural fine tuning.

James M. Gelb, S. P. Rosen

We consider the effect of thermal broadening of the $^7$Be neutrino on vacuum oscillation solutions of the solar neutrino problem and analyze the conditions under which the electron-neutrino survival probability must be averaged over neutrino energy. For "just-so" solutions with $Δm^2$ of order $5 \times 10^{-11}~{\rm eV}^2$ averaging is not necessar

Martin J. Savage

The rare decay K_L -> pi pi e e that has recently been observed by KTeV is analyzed in chiral perturbation theory at the one-loop level.

Mikkel B. Johnson, Leonard S. Kisslinger

We propose an analog of the familiar gap equation for the case of four-quark condensates at finite temperature. The condensates of interest correspond to scalar, vector, psudoscalar, axial vector, and tensor Dirac structures. Working with correlators at zero chemical potential without factorization, we arrive at coupled equations for these four-quark condens

V. V. Kiselev, A. E. Kovalsky

The fragmentation function of vector particle into possible bound S-wave states with a heavy antiquark is calculated in the leading order of perturbative QCD for the high energy processes at large transverse momenta with the different behaviour of anomalous chromomagnetic moment. One-loop equations are derived for the evolution of fragmentation function mome

L. A. Mikaelyan, V. V. Sinev

We shortly review past and future experiments at reactors aimed at searches for neutrino masses and mixing. We also consider new idea to search at Krasnoyarsk for small mixing angle oscillations in the atmosheric neutrino mass parameter region.

J. Z. Bai

Using the upgraded Beijing Spectrometer (BESII), we have measured the total cross section for $e^+e^-$ annihilation into hadronic final states at center-of-mass energies of 2.6, 3.2, 3.4, 3.55, 4.6 and 5.0 GeV. Values of $R$, $σ(e^+e^-\to {hadrons})/σ(e^+e^-\toμ^+μ^-)$, are determined.

Dieter Maison, Steven L. Liebling

Using mainly analytical arguments, we derive the exact relation $η_{max}=\sqrt{3/8π}$ for the maximal vacuum value of the Higgs field for static gravitational global monopoles. For this value, the global monopole bifurcates with the de Sitter solution obtained for vanishing Higgs field. In addition, we analyze the stability properties of the solutions.

Carmen Molina-Paris, Paul R. Anderson, Stephen A. Ramsey

The renormalization of a scalar field theory with a quartic self-coupling (a $λϕ^4$ theory) via adiabatic regularization in a general Robertson-Walker spacetime is discussed. The adiabatic counterterms are presented in a way that is most conducive to numerical computations. A variation of the adiabatic regularization method is presented which leads to analyt

C. C. Briggs

A simple derivation is given of the Einstein-Maxwell field equations from the 2nd ordinary exterior differential of a precursor to the soldering form for n-dimensional differentiable manifolds having a general linear connection and in 5-dimensional general relativity in particular.

C. C. Briggs

A sequence of generalizations of Cartan's conservation of torsion theorem is given for n-dimensional differentiable manifolds having a general linear connection.

C. C. Briggs

A simple formula is given for generating Chern characters by repeated exterior differentiation for n-dimensional differentiable manifolds having a general linear connection.

Erik D. Demaine, Joseph O'Rourke

Open problems from the 15th Annual ACM Symposium on Computational Geometry.

Thorsten Emig, Philippe Claudin, Jean-Philippe Bouchaud

We present exact solutions of the non-linear {\sc bcre} model for granular avalanches without diffusion. We assume a generic sandpile profile consisting of two regions of constant but different slope. Our solution is constructed in terms of characteristic curves from which several novel predictions for experiments on avalanches are deduced: Analytical result

M. Fuchs, M. R. Mayr

Results of the idealized mode-coupling theory for the structural relaxation in suspensions of hard-sphere colloidal particles are presented and discussed with regard to recent light scattering experiments. The structural relaxation becomes non-diffusive for long times, contrary to the expectation based on the de Gennes narrowing concept. A semi-quantitative

Robert Leary, Jonathan Doye

A new atomic cluster structure corresponding to the global minimum of the 98-atom Lennard-Jones cluster has been found using a variant of the basin-hopping global optimization algorithm. The new structure has an unusual tetrahedral symmetry with an energy of -543.665361, which is 0.022404 lower than the previous putative global minimum. The new LJ_98 structu

T. K. Ng

We study in this paper the properties of a gas of fermions interacting {\em via} a scalar potential $v(q)=4π{e}^2/q^2$ for $q<Λ<<k_F$ at dimensions larger than one, where $Λ$ is a high momentum cutoff and $k_F$ is the fermi wave vector. In particular, we shall consider the $e^2\to\infty$ limit where the potential becomes confining. Within a bosonization appr

Y. L. Liu, T. K. Ng

In this paper we study a model of s-wave marginal Fermi liquid superconductor at two dimensions. Besides the usual Bardeen-Cooper-Schrieffer(BCS) point attractive interaction, the fermions in our system also interact {\em via} a long range repulsive interaction $v(q)=g_{D}/q^2$. We find that although superconductivity is not destroyed by the long-ranged repu

Chi-Ho Cheng, T. K. Ng

The supersymmetric formulation of t-J model is studied in this paper at the mean-field level where $δ$-T phase diagram is computed. We find that slave-fermion-like spiral phase is stable at low doping concentration, and the slave-boson-like d-wave fermionic spin pairing state becomes energetically favourable when $δ\geq$ 0.23. An improvement in free energy u

S. Pleutin, E. Jeckelmann, M. A. Martin-Delgado, G. Sierra

In this note, first the Recurrent Variational Approach (RVA) is introduced by using as example a non-trivial spin-model, the spin-1/2 antiferromagnetic two-leg-ladder. Then, a first application of this scheme to the electronic structure of conjugated polymers is proposed. An analogy between the two-leg ladder and the dimerized chain described by the Extended

Mike Guidry, Lian-Ao Wu, Yang Sun, Cheng-Li Wu

We present an SU(4) model of high-$T_c$ superconductivity. One dynamical symmetry of this model corresponds to the previously proposed SO(5) model for unification of superconductivity and antiferromagnetism, but there are two additional dynamical symmetries: SO(4), associated with antiferromagnetic order and SU(2), associated with a D-wave pairing condensate

D. Andrew Howell, Lifan Wang, J. Craig Wheeler

The distribution of high redshift Type Ia supernovae (SNe Ia) with respect to projected distance from the center of the host galaxy is studied and compared to the distribution of local SNe. The distribution of high-z SNe Ia is found to be similar to the local sample of SNe Ia discovered with CCDs, but different than the sample discovered photographically. Th

Scott J. Kenyon, Kenneth Wood, Barbara A. Whitney, Michael J. Wolff

We describe planetesimal accretion calculations for the dusty ring observed in the nearby A0 star HR 4796A. Models with initial masses of 10-20 times the minimum mass solar nebula produce a ring of width 7-15 AU and height 0.3-0.6 AU at 70 AU in roughly 10 Myr. The ring has a radial optical depth of 1. These results agree with limits derived from infrared im

Yu. N. Gnedin, S. O. Kiikov

We consider the phenomenon of a gamma-ray burst as a nonlinear collapse of a magnetic cavity surrounding a neutron star with very strong magnetic field B = 10^15 - 10^16 G due to the process of the bubble shape instability in a resonant MHD field of the accreting plasma. The QED effect of vacuum polarizability by the strong magnetic field is taken into accou

M. S. Sahu, W. Landsman, F. C. Bruhweiler, T. R. Gull

We reinvestigate the question of spatial variation of the local D/H abundance, using both archival GHRS spectra, and new echelle spectra of G191-B2B obtained with the Space Telescope Imaging Spectrograph (STIS) aboard HST. Our analysis uses stratified line-blanketed non-LTE model atmosphere calculations to determine the shape of the intrinsic WD Lyman-alpha

Masatoshi Imanishi, Shiro Ueno

We report the results of hard X-ray observations of four multinuclei merging infrared luminous galaxies (IRLGs). We selected these four sources for their excess of radio to far-infrared luminosity ratio compared with starburst galaxies. This excess suggests that activity associated with a supermassive black hole (SMBH) contributes strongly to the IRLGs&#39;

J. S. B. Wyithe, R. L. Webster, E. L. Turner

Spectrophotometric observation of the gravitationally microlensed quasar Q2237+0305 during a High Magnification Event (HME) is potentially a very powerful tool for probing the structure of the quasars accretion disc on scales of less than 10^-8 arc seconds. How often we can expect to observe a HME is dependent on the lens system parameters of galactic transv

Grigory I. Barenblatt, Alexandre J. Chorin, V. M. Prostokishin

Processing the data from a large variety of zero-pressure-gradient boundary layer flows shows that the Reynolds-number-dependent scaling law, which the present authors obtained earlier for pipes, gives an accurate description of the velocity distribution in a self-similar intermediate region of distances from the wall adjacent to the viscous sublayer. The ap

Eda Cesaratto

This paper has been withdrawn Any real number $x$ in the unit interval can be expressed as a continued fraction $x=[n_1,...,n_{_N},...]$. Subsets of zero measure are obtained by imposing simple conditions on the $n_{_N}$. By imposing $n_{_N}\le m \forall N\in \zN$, Jarnik defined the corresponding sets $E_m$ and gave a first estimate of $d_H(E_m)$, $d_H$ the

Ted Jacobson

I argue that black hole entropy counts only those states of a black hole that can influence the outside, and attempt (with only partial success) to defend this claim against various objections, all but one coming from string theory. Implications for the nature of the Bekenstein bound are discussed, and in particular the case for a holographic principle is ch

Jaume Garriga, Alexander Vilenkin

We discuss models in which the smallness of the effective vacuum energy density $ρ_Ł$ and the coincidence of the time of its dominance $t_Ł$ with the epoch of galaxy formation $t_G$ are due to anthropic selection effects. In such models, the probability distribution for $ρ_Ł$ is a product of an {\it a priori} distribution ${\cal P}_*(ρ_Ł)$ and of the number

Alexander A. Voronov

The goal of this paper is to complete Getzler-Jones&#39; proof of Deligne&#39;s Conjecture, thereby establishing an explicit relationship between the geometry of configurations of points in the plane and the Hochschild complex of an associative algebra. More concretely, it is shown that the $B_\infty$-operad, which is generated by multilinear operations know

E. Levin, K. Tuchin

In this paper a solution is given to the nonlinear equation which describes the evolution of the parton cascade in the case of the high parton density. The related physics is discussed as well as some applications to heavy ion-ion collisions.

Scott T. Kay, F. R. Pearce, A. Jenkins, C. S. Frenk

Numerical simulations of galaxy formation require a number of parameters. Some of these are intrinsic to the numerical integration scheme (eg the timestep), while others describe the physical model (eg the gas metallicity). In this paper, we present results of a systematic exploration of the effects of varying a subset of these parameters on simulations of g

Y. Wiaux

A specific choice of gauge is shown to imply a decoupling between the tensor and scalar components of Gravitational Radiation in the context of Brans-Dicke type theories of gravitation. The comparison of the predictions of these theories with those of General Relativity is thereby made straightforward.

Hagen Kleinert

We show that the calculation of L-loop Feynman integrals in D dimensions can be reduced to a series of matrix multiplications in D times L dimensions. This gives rise to a new type of expansions for the critical exponents in three dimensions in which all coefficients can be calculated exactly.

Mohan Narayan, G. Rajasekaran, Rahul Sinha, C. P. Burgess

The solar neutrino counting rate in a real time detector like Super--Kamiokanda, SNO, or Borexino is enhanced due to neutrino oscillations in the Moon during a partial or total solar eclipse. The enhancement is calculated as a function of the neutrino parameters in the case of three flavor mixing. This enhancement, if seen, can further help to determine the

J. Z. Bai

BES data on $J/ψ\to γ(K^+K^-π^+π^-)$ are presented. The $K^*\bar K^*$ contribution peaks strongly near threshold. It is fitted with a broad $0^{-+}$ resonance with mass $M = 1800 \pm 100$ MeV, width $Γ= 500 \pm 200$ MeV. A broad $2^{++}$ resonance peaking at 2020 MeV is also required with width $\sim 500$ MeV. There is further evidence for a $2^{-+}$ compone

Micho Durdevich

The paper is a brief informal introduction to C*-algebraic foundations of causal contextual subquantum theories. In particular, it is explained how the contextuality property (which is a necessary consistency condition of all causal subquantum theories) naturally appears within the framework of certain C*-algebraic extensions of the quantum observables algeb