September 1999 arXiv papers — page 21

P. Coleman, C. Pepin, A. M. Tsvelik

We develop a supersymmetric representation of spin operators which unifies the Schwinger and Abrikosov representations of SU(N) spin operators, allowing a second-quantized treatment of representations of the SU(N) group with both symmetric and antisymmetric character. By applying this to the SU(N) Kondo model, we show that it is possible to develop a control

Konstantin Varnashev

The detailed analysis of the global structure of the renormalization-group (RG) flow diagram for a model with isotropic and cubic interactions is carried out in the framework of the massive field theory directly in three dimensions (3D) within an assumption of isotropic exchange. Perturbative expansions for RG functions are calculated for arbitrary $N$ up to

Maciej Bak, Roman Micnas

We examine extended bound states in the dilute limit of the extended Hubbard model with next-nearest-neighbour (nnn) hopping and nnn interactions on the two dimensional square lattice. By the exact solution of a two-body problem we show that d-wave pairing is strongly favored by the nnn hopping. We determine the binding energies, mobilities and dispersion cu

P. Cea, L. Tedesco

We investigate (2+1)-dimensional QED coupled with Dirac fermions both at zero and finite temperature. We discuss in details two-components (P-odd) and four-components (P-even) fermion fields. We focus on P-odd and P-even Dirac fermions in presence of an external constant magnetic field. In the spontaneous generation of the magnetic condensate survives even a

A. Hanany, B. Kol, A. Rajaraman

We identify the lift to M theory of the four types of orientifold points, and show that they involve a chiral fermion on an orbifold fixed circle. From this lift, we compute the number of normalizable ground states for the SO(N) and $Sp(N)$ supersymmetric quantum mechanics with sixteen supercharges. The results agree with known results obtained by the mass d

Emili Bagan, Martin Lavelle, David McMullan

There is a widespread belief in particle physics that there is no relativistic description of a charged particle. This is claimed to be due to persistent, long range interactions which distort the in and out going plane waves and generate infra-red divergences. In this paper we will show that this is not the case in QED. We construct locally gauge invariant

Emili Bagan, Martin Lavelle, David McMullan

Gauge theories are characterised by long range interactions. Neglecting these interactions at large times, and identifying the Lagrangian matter fields with the asymptotic physical fields, leads to the infra-red problem. In this paper we study the perturbative applications of a construction of physical charges in QED, where the matter fields are combined wit

Bastian Bergerhoff, Manfred Lindner, Manfred Weiser

We study the question whether a possible metastable vacuum state is actually populated in a phase transition in the early universe, as is usually assumed in the discussion of vacuum stability bounds e.g. for Standard Model parameters. A phenomenological (3+1)-dimensional Langevin equation is solved numerically for a toy model with a potential motivated by th

S. Rai Choudhury, Naveen Gaur, Abhinav Gupta

A complete experiment on decay $K_L \to l^+ l^-$ will not only consist of measurement of the decay rates but also lepton polarization etc. These additional observations will yield tests of CP invariance in these decays. In $K_L$ and $K_S$ decays, the e mode is slower than the $μ$ mode by roughly $(m_e/m_μ)^2$ \cite{sehgal1}. As well discussed in literature \

U. Ellwanger, C. Hugonie

We study the upper limits on the mass of the lightest and second lightest CP even Higgs bosons in the (M+1)SSM, the MSSM extended by a gauge singlet. The dominant two loop contributions to the effective potential are included, which reduce the Higgs masses by 10 GeV. Since the coupling R of the lightest Higgs scalar to gauge bosons can be small, we study in

D. Boyanovsky, H. J. de Vega, M. Simionato

We study the generation of a non-equilibrium plasma in scalar QED with N charged scalar fields through spinodal instabilities in the case of a super cooled second order phase transition and parametric amplification when the order parameter oscillates with large amplitude around the minimum of the potential.The focus is to study the non-equilibrium electromag

Werner Kerler

Establishing an exact relation for the derivative we show that the eigenvalue flows of the hermitean Wilson-Dirac operator obey a differential equation. We obtain a complete overview of the characteristic features of its solutions. The underlying mathematical aspects are fully clarified.

Koji Hashimoto

In this paper, we generalize a boundary state to the one incorporating non-constant gauge field strength as an external background coupled to the boundary of a string worldsheet in bosonic string theory. This newly defined boundary state satisfies generalized nonlinear boundary conditions with non-constant gauge field strength, and is BRST invariant. The div

Vladimir A. Sablikov, Yasha Gindikin

The density operator in the Luttinger model consists of two components, one of which describes long-wave fluctuations and the other is related to the rapid oscillations of the charge-density-wave (CDW) type, caused by short-range electron correlations. It is commonly believed that the conductance is determined by the long-wave component. The CDW component is

Metin Gurses, Atalay Karasu, Vladimir Sokolov

In this work we develop a general procedure for constructing the recursion operators fro non-linear integrable equations admitting Lax representation. Svereal new examples are given. In particular we find the recursion operators for some KdV-type of integrable equations.

A. S. Parkins, H. J. Kimble

We propose a scheme for teleporting an atomic center-of-mass wave function between distant locations. The scheme uses interactions in cavity quantum electrodynamics to facilitate a coupling between the motion of an atom trapped inside a cavity and external propagating light fields. This enables the distribution of quantum entanglement and the realization of

M. A. Nielsen

A density matrix $ρ$ may be represented in many different ways as a mixture of pure states, $ρ= \sum_i p_i |ψ_i\ra \la ψ_i|$. This paper characterizes the class of probability distributions $(p_i)$ that may appear in such a decomposition, for a fixed density matrix $ρ$. Several illustrative applications of this result to quantum mechanics and quantum informa

Martti Havukainen

We show how two level atoms can be used to determine the local time dependent spectrum. The method is applied to a one dimensional cavity. The spectrum obtained is compared with the mode spectrum determined using spatially filtered second order correlation functions. The spectra obtained using two level atoms give identical results with the mode spectrum. On

Marc-Oliver Mewes, Gabriele Ferrari, Florian Schreck, Alice Sinatra

We confine 4 10^8 fermionic 6Li atoms simultaneously with 9 10^9 bosonic 7Li atoms in a magneto-optical trap based on an all-semiconductor laser system. We optimize the two-isotope sample for sympathetic evaporative cooling. This is an essential step towards the production of a quantum-degenerate gas of fermionic lithium atoms.

Gerard van der Geer, Marcel van der Vlugt

We give a method for constructing Kummer covers with many points over finite fields.

Osamu Fujino

Let $(P\in X,Δ)$ be a three dimensional log canonical pair such that $Δ$ has only standard coefficients and $P$ is a center of log canonical singularities for $(X,Δ)$. Then we get an effective bound of the indices of these pairs and actually determine all the possible indices. Furthermore, under certain assumptions including the log Minimal Model Program, an

A. I. Molev

This paper completes a series devoted to explicit constructions of finite-dimensional irreducible representations of the classical Lie algebras. Here the case of odd orthogonal Lie algebras (of type B) is considered (two previous papers dealt with C and D types). A weight basis for each representation of the Lie algebra o(2n+1) is constructed. The basis vect

Izabella Laba, Terence Tao

We prove an x-ray estimate in general dimension which is stronger than the Kakeya estimates of Wolff. This generalizes an x-ray estimate in three dimensions which is also due to Wolff.

Charles H. C. Little, Franz Rendl, Ilse Fischer

A bipartite graph G is known to be Pfaffian if and only if it does not contain an even subdivision H of $K_{3,3}$ such that $G - VH$ contains a 1-factor. However a general characterisation of Pfaffian graphs in terms of forbidden subgraphs is currently not known. In this paper we describe a possible approach to the derivation of such a characterisation. We a

D. Talalaev

The expression of the quantum Ruijsenaars-Schneider Hamiltonian is obtained in the framework of the dynamical $R$-matrix formalism. This generalizes to the case of $U_q(sl_n)$ the result obtained by O. Babelon, D. Bernard and E. Billey for $U_q(sl_2)$ which is the higher difference Lame operator. The general method involved is the universal $R$-matrix constr

Terence Tao

We show that a homogeneous convolution kernel on an arbitrary homogeneous group which is L \log L on the unit annulus is bounded on L^p for 1 < p < \infty and is of weak-type (1,1), generalizing the result of Seeger. The proof is in a similar spirit to that of Christ and Rubio de Francia.

Yoshitaka Kuno, Yasuhiro Okada

This article reviews the current theoretical and experimental status of the field of muon decay and its potential to search for new physics beyond the Standard Model. The importance of rare muon processes with lepton flavor violation is highly stressed, together with precision measurements of normal muon decay. Recent up-to-date motivations of lepton flavor

John M. LoSecco

This paper reviews the history of the atmospheric neutrino anomaly. The historical record does not support more recent claims that the anomaly constitutes evidence for a neutrino mass. Most experiments have reported an apparent muon deficiency which is independent of energy and distance. Time dependent variations in the Super Kamioka results are noted.

S. Munier, H. Navelet

To study diffractive photon production at HERA, we compute the projection of the virtual photon-photon impact-factor on the BFKL leading-order eigenfunctions E(n,nu) for non-zero transfer. This calculation supplements former ones performed for n=0. We provide an expression for n=+/-2 and check that all the other components are zero.

Rouzbeh Allahverdi, Bruce A. Campbell, R. H. A. David Shaw

Recently, there have been studies of parametric resonance decay of oscillating real homogeneous cosmological scalar fields, in both the narrow-band and broad-band case, primarily within the context of inflaton decay and (p)reheating. However, many realistic models of particle cosmology, such as supersymmetric ones, inherently involve complex scalar fields. I

H. Davoudiasl, J. L. Hewett, T. G. Rizzo

We explore the phenomenology associated with the recently proposed localized gravity model of Randall and Sundrum where gravity propagates in a 5-dimensional non-factorizable geometry and generates the 4-dimensional weak-Planck scale hierarchy by an exponential function of the compactification radius, called a warp factor. The Kaluza-Klein tower of gravitons

B. Alles, L. Cosmai, M. D&#39;Elia, A. Papa

Various cooling methods, including a recently introduced one which smoothes out only quantum fluctuations larger than a given threshold, are applied to the study of topology in 2d CP(N-1) models. A critical comparison of their properties is performed.

Alun George

The dynamical triangulations approach to quantum gravity is investigated in detail for the first time in five dimensions. In this case, the most general action that is linear in components of the f-vector has three terms. It was suspected that the corresponding space of couplings would yield a rich phase structure. This work is primarily motivated by the hop

M. E. Berbenni, T. Guhr, J. -Z. Ma, S. Meyer

Random matrix theory (RMT) is a powerful statistical tool to model spectral fluctuations. In addition, RMT provides efficient means to separate different scales in spectra. Recently RMT has found application in quantum chromodynamics (QCD). In mesoscopic physics, the Thouless energy sets the universal scale for which RMT applies. We try to identify the equiv

Seyong Kim

Using commodity component personal computers based on Alpha processor and commodity network devices and a switch, we built an 8-node parallel computer. GNU/Linux is chosen as an operating system and message passing libraries such as PVM, LAM, and MPICH have been tested as a parallel programming environment. We discuss our lattice QCD project for a heavy quar

S. Bonazzola, E. Gourgoulhon, P. Grandclement, J. -A. Marck

A review is given of recent results about the computation of irrotational Darwin-Riemann configurations in general relativity. Such configurations are expected to represent fairly well the late stages of inspiralling binary neutron stars.

G. L. Alberghi, R. Casadio, G. Venturi

An effective action is obtained for the area and mass aspect of a thin shell of radiating self-gravitating matter. On following a mini-superspace approach, the geometry of the embedding space-time is not dynamical but fixed to be either Minkowski or Schwarzschild inside the shell and Vaidya in the external space filled with radiation. The Euler-Lagrange equa

Weiqiang Yu, Stephan Haas

The dynamical spin structure factor and the Raman response are calculated for structurally dimerized and spin-Peierls chains in a magnetic field, using exact diagonalization techniques. In both cases there is a spin liquid phase composed of interacting singlet dimers at small fields h < h_c1, an incommensurate regime (h_c1 < h < h_c2) in which the modulation

Shiwei Zhang

We present a quantum Monte Carlo method which allows calculations on many-fermion systems at finite temperatures without any sign decay. This enables simulations of the grand-canonical ensemble at large system sizes and low temperatures. Both diagonal and off-diagonal expectations can be computed straightforwardly. The sign decay is eliminated by a constrain

Shiwei Zhang

This article contains lecture notes on the constrained path Monte Carlo method and its applications to study the Hubbard model. The lectures were given at the NATO Advanced Summer Institute held in Ithaca NY (1998). The article is published as a chapter in the book `Quantum Monte Carlo Methods in Physics and Chemistry,&#39; Ed. M.P. Nightingale and C.J. Umri

Richard P. Sear

Recent work on charged colloidal suspensions with very low levels of added salt has suggested that although pairs of the colloidal particles repel, clusters of the particles attract. Motivated by this, we study simple model particles which have many-body attractions. These attractions are generic many-body attractions and are not calculated for any specific

F. M. Araujo-Moreira, P. N. Lisboa Filho, S. M. Zanetti, E. R. Leite

Superconductivity in thin films and powders, and in single crystals of Pr-123 has been found by Blackstead et al. and Zou et al., respectively. Nevertheless, up to now it has never been reported in sintered-policrystalline samples. We have prepared high-quality samples of this material by following a sol-gel method. We characterized the structure of all samp

Romuald A. Janik, Maciej A. Nowak, Gabor Papp, Ismail Zahed

We review some recent techniques for dealing with non-hermitian random matrix models based on generalized Green&#39;s functions. We introduce the diagrammatic methods in the hermitian case and generalize them to the non-hermitian case. The results are illustrated in terms of the eigenvalue distribution, eigenvector statistics and addition laws.

Gianaurelio Cuniberti, Andrea Fechner, Maura Sassetti, Bernhard Kramer

The DC current-voltage characteristics, induced by a driving electric field with frequency Omega, of a one dimensional electron channel with a tunnel barrier is calculated. Electron-electron interaction of finite-range is taken into account. For intermediate interaction strengths, the non-linear differential conductance shows cusp-like minima at bias voltage

O. Kirillova

In this work we study the Boolean Networks of different geometric shape and lattice organization. It was revealed that no only a spatial shape but also type of lattice are very important for definition of the structure-dynamics relation. The regular structures do not give a critical regime in the investigated cases. Hierarchy together with the irregular stru

Olga Kirillova

In this paper, results of investigations of the simplest mechanisms of a structure formation are presented. In frameworks of the suggested model the main attention was focused on such characteristics as wiring of the system, clusters formation, dynamics of the wiring. The idea to take into account an influence of the environment factor is employed in the pro

Dmitry N. Aristov, Daniel R. Grempel

We study the spin fluctuation dynamics of Cu-O chains in the oxygen deficient planes of YBa(2)Cu(3)O(6+x). The chains are described by a model including antiferromagnetic interactions between the spins and Kondo-like scattering of the oxygen holes by the copper spins. There are incommensurate spin fluctuations along the direction of the chains. The dynamic s

I. Ya. Korenblit, A. Aharony, O. Entin-Wohlman

The effect of localized holes on the long-range antiferromagnetic order in bilayer cuprates is studied, by applying the renormalization group to the appropriate non-linear sigma model. The theory accounts quantitatively for the magnetic phase diagram of Ca doepd YBa_2Cu_3O_6.

Sergei V. Berezovsky

Nonlinear properties of the order parameter modulation wave in such systems as thiourea are described in the framework of the phenomenological model with no Lifshitz invariant. It is also shown that for some values of the thermodynamic potential parameters the lock-in transition is continuous in the type II systems. Close to this transition the soliton latti

David Hochberg, Carmen Molina-Paris, Juan Perez-Mercader, Matt Visser

In previous work [cond-mat/9904207,cond-mat/9904215] we have developed a general method for casting stochastic partial differential equations (SPDEs) into a functional integral formalism, and have derived the one-loop effective potential for these systems. In this paper we apply the same formalism to a specific field theory of considerable interest, the reac

H. Jin, J. Kötzler

Single crystals of the layered superconductor Bi2Sr2(Ca1-xLax)Cu2O8+d were successfully grown out by a self-flux method. Upon La-doping, the c-axis contracts but the structure remains stable up to the critical concentration xc, above which the crystals contain the pure Bi2(Sr,La)2CuO6 phase. The reduction of the superconducting transition temperature follows

H. Jin, S. Skwirblies, J. Kötzler

Bi2Sr2-xLaxCaCu2O8+d superconducting whiskers were successfully grown from Bi-rich meltscontaining various La contents. Effect of La-doping on the whisker growth, structure and superconductivity has been studied. It has been found that the whiskers can be grown only from La-doped melts, no whisker was obtained from the La-free melt x=0. Within the doping reg

Yoshihiro ASAI

We have studied the ground state of the two-dimensional Hubbard model by using the adaptive sampling quantum monte carlo method. We found enhancement of the d-wave correlation function, the spin gap and the coexistence of both the commensurate and incommensurate peaks in $S(\vec{q})$, which does not contradict a recent experimental finding that both the reso

A. Zyuzin, B. Spivak, I. Vagner, P. Wyder

We discuss a mesoscopic mechanism of exchange interaction in ferromagnet-normal metal-ferromagnet multilayers. We show that in the case when the metal&#39;s thickness is larger than the electron mean free path, the relative orientation of magnetizations in the ferromagnets is perpendicular. The exchange energy between ferromagnets decays with the metal thick

Thomas Papenbrock

We compute the Lyapunov exponents and the Kolmogorov-Sinai (KS) entropy for a self-bound N-body system that is realized as a convex billiard. This system exhibits truly high-dimensional chaos, and 2N-4 Lyapunov exponents are found to be positive. The KS entropy increases linearly with the numbers of particles. We examine the chaos generating defocusing mecha

J. Main, P. A. Dando, Dz. Belkic, H. S. Taylor

Periodic orbit quantization requires an analytic continuation of non-convergent semiclassical trace formulae. We propose a method for semiclassical quantization based upon the Pade approximant to the periodic orbit sums. The Pade approximant allows the re-summation of the typically exponentially divergent periodic orbit terms. The technique does not depend o

E. A. Baltz, C. Briot, P. Salati, R. Taillet

We consider neutralino annihilation in dense extragalactic systems known to be dominated by dark matter, in particular M87 and several local dwarf spheroidal galaxies. These annihilations can produce energetic gamma rays which may be visible to atmospheric Cerenkov telescopes. We explore the supersymmetric parameter space, and compute the expected flux of ga

Daniel D. Kelson, Garth D. Illingworth, Marijn Franx, Pieter G. van Dokkum

The $M/L$ ratios and absorption line-strengths of distant cluster galaxies can be used to directly study their stellar populations, determine their redshift of formation, their scatter in ages, and any dependence of their ages on such internal properties such as velocity dispersion or mass. Comparing the zero-point the fundamental plane in the $z=0.33$ clust

F. Courbin, P. Magain, M. Kirkove, S. Sohy

A method for spatial deconvolution of spectra is presented. It follows the same fundamental principles as the ``MCS image deconvolution algorithm&#39;&#39; (Magain, Courbin, Sohy, 1998) and uses information contained in the spectrum of a reference Point Spread Function (PSF) to spatially deconvolve spectra of very blended sources. An improved resolution rath

E. Oliva

I very briefly describe the latest generation near infrared (1-2.5 micron) instruments which are available on, or under development for `large&#39; (D>=3.5 m) telescopes. Most of the imagers under construction are limited to relatively small fields, while the spectrometers aim at quite high resolving powers. The alternative instruments which I discuss here a

G. Houdek, N. J. Balmforth, J. Christensen-Dalsgaard, D. O. Gough

We present estimates of the amplitudes of intrinsically stable stochastically excited radial oscillations in stars near the main sequence. The amplitudes are determined by the balance between acoustical energy generation by turbulent convection (the Lighthill mechanism) and linear damping. Convection is treated with a time-dependent, nonlocal, mixing-length

You-Hua Chu, Martin A. Guerrero, Robert A. Gruendl

Two sources of X-ray emission are expected from planetary nebulae: the hot central stars with $T_{eff} > 10^5$ K, and shocked fast stellar winds at temperatures of 10$^6 - 10^7$ K. The stellar emission and nebular emission differ in spatial distribution and spectral properties. Observations of X-ray emission from PNe may provide essential information on form

A. L. Roy, J. S. Ulvestad, A. S. Wilson, E. J. M. Colbert

Seyfert galaxies come in two main types (types 1 and 2) and the difference is probably due to obscuration of the nucleus by a torus of dense molecular material. The inner edge of the torus is expected to be ionized by optical and ultraviolet emission from the active nucleus, and will radiate direct thermal emission (e.g. NGC 1068) and will cause free-free ab

Alfred Krabbe, Juergen Wolf

LISA is a proposed low resolution (R~15-30) imaging spectrometer for SOFIA, the American-German Stratospheric Observatory for Far Infrared Astronomy. Covering the wavelength range from 40micron to 220micron with three channels, LISA provides diffraction limited spectroscopy for each pixel within a rectangular field of view (FOV). The FOV sizes for the channe

Rien van de Weygaert, Yehuda Hoffman

Unlike the substantial coherent bulk motion in which our local patch of the Cosmos is participating, the amplitude of the random motions around this large scale flow seems to be surprisingly low. Attempts to invoke global explanations to account for this coldness of the local cosmic velocity field have not yet been succesfull. Here we propose a different vie

Angeles I. Diaz, Mar Alvarez Alvarez, Elena Terlevich, Roberto Terlevich

V,R,I continuum bands and Halpha + [NII] photometry for circumnuclear star forming regions (CNSFR) is presented, for galaxies with different kinds of nuclear activity: NGC 7469 (Sy 1), NGC 1068 (Sy 2), NGC 7177 (LINER) and NGC 3310 (Starburst). Their Halpha luminosities (0.02 - 7x10**40 erg/s; uncorrected for internal extinction), are comparable to those obs

D. Grupe, H. -C. Thomas, K. M. Leighly

We report the discovery of a new X-ray transient AGN, RX J1624.9+7554. This object appeared to be bright in the ROSAT All-Sky Survey, but had turned off in two pointed observations about one and a half years later. The optical identification spectrum shows a non-emission line spectrum of a spiral galaxy at z=0.064. %We will discuss several hypotheses that ca

C. Mayen, G. Soucail

When the logarithmic slope of the galaxy counts is lower than 0.4 (this is the case in all filters at high magnitude), the magnification bias due to the lens makes the number density of objects decrease. Consequently, the radial distribution shows a typical depletion curve. We present simulations of depletion curves obtained for a variety of different lens m

C. H. Ishwara-Chandra, D. J. Saikia

We present radio images of two giant quasars from the Molonglo/1Jy sample, and make a comparative study of giant radio sources selected from the literature with 3CR radio sources of smaller sizes to investigate the evolution of giant sources, and test their consistency with the unified scheme. The luminosity-size diagram shows that the giant sources are less

A. J. Weinberger, E. E. Becklin, G. Schneider, B. A. Smith

Coronagraphic imaging with the Near Infrared Camera and Multi Object Spectrometer on the Hubble Space Telescope reveals a large, ~400 AU (4&#39;&#39;) radius, circumstellar disk around the Herbig Ae/Be star HD 141569. A reflected light image at 1.1 micron shows the disk oriented at a position angle of 356 +/- 5 deg and inclined to our line of sight by 51 +/-

K. I. Kellermann, E. A. Richards

Deep radio surveys show a population of very red counterparts of microjansky radio sources, which are unidentified to I = 25 in ground based images and I = 28.5 in the Hubble Deep Field. This population of optically faint radio sources, which comprises about 20% of the microjansky radio samples, may be dust enshrouded starburst galaxies, extreme redshift or

Paolo Aschieri, Daniel Brace, Bogdan Morariu, Bruno Zumino

We show that the Born-Infeld theory with n complex abelian gauge fields written in an auxiliary field formulation has a U(n,n) duality group. We conjecture the form of the Lagrangian obtained by eliminating the auxiliary fields and then introduce a new reality structure leading to a Born-Infeld theory with n real fields and an Sp(2n,R) duality symmetry. The

Béla Bollobás, Christian Borgs, Jennifer T. Chayes, Jeong Han Kim

We consider the random 2-satisfiability problem, in which each instance is a formula that is the conjunction of m clauses of the form (x or y), chosen uniformly at random from among all 2-clauses on n Boolean variables and their negations. As m and n tend to infinity in the ratio m/n --> alpha, the problem is known to have a phase transition at alpha_c = 1,

Yong-Hoon Kim, Martin Städele, Richard M. Martin

We report density-functional studies of several small molecules ($H_{2}, N_{2}, CO, H_{2}O$, and $CH_{4}$) within the Krieger-Li-Iafrate (KLI) approximation to the exact Kohn-Sham local exchange potential, using a three-dimensional real-space finite-difference pseudopotential method. It is found that exchange-only KLI leads to markedly improved eigenvalue sp

Ken Nakanishi

Newell-Whitham type car-following model with hyperbolic tangent optimal velocity function in a one-lane circuit has a finite set of the exact solutions for steady traveling wave, which expressed by elliptic theta function. Each solution of the set describes a density wave with definite number of car-bunches in the circuit. By the numerical simulation, we obs

Mikhail Menshikov, Konstantine Rybnikov, Stanislav Volkov

If one randomly punches holes in an infinite tensed membrane, when does the tension cease to exist? This problem was introduced by R. Connelly in connection with applications of rigidity theory to natural sciences. We outline a mathematical theory of tension based on graph rigidity theory and introduce several probabilistic models for this problem. We show t

Grigory Garkusha

The general theory of Grothendieck categories is presented. We systemize the principle methods and results of the theory, showing how these results can be used for studying rings and modules.

A. Donini, M. B. Gavela, P. Hernandez, S. Rigolin

The prospects of measuring the leptonic angles and CP-odd phases at a neutrino factory are discussed in two scenarios: 1) three active neutrinos as indicated by the present ensemble of atmospheric plus solar data; 2) three active plus one sterile neutrino when the LSND signal is also taken into account. For the latter we develop one and two mass dominance ap

M. Göckeler, R. Horsley, W. Kürzinger, H. Oelrich

A recent lattice calculation of the spin-dependent structure function g_2 is revisited. It has been recognized that the twist-three operator, which gives rise to d_2, mixes non-perturbatively with operators of lower dimensions under renormalization. This changes the results substantially.

T. Affolder, CDF Collaboration

We have studied the production of B hadrons in 1.8-TeV p-pbar collisions. We present measurements of the fragmentation fractions, f_u, f_d, f_s and f_baryon, of produced b quarks that yield B^+, B^0, B^0_s and Lambda_b hadrons. Reconstruction of several electron-charm final states yields f_s/(f_u+f_d)=0.213+/-0.068 and f_baryon/(f_u+f_d)=0.118+/-0.042, assum

Ronald J. Adler, Ilya M. Nemenman, James M. Overduin, David I. Santiago

We discuss a recent provocative suggestion by Amelino-Camelia and others that classical spacetime may break down into ``quantum foam&#39;&#39; on distance scales many orders of magnitude larger than the Planck length, leading to effects which could be detected using large gravitational wave interferometers. This suggestion is based on a quantum uncertainty l

Weimin Chen, J. P. Franck, J. Jung

We report peculiar vortex motion in clean Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystals, which reveals nearly linear-$T$ resistivity tails extending to low temperatures. The resistivity was found to satisfy the classical Bardeen-Stephen model for free flux flow, which is otherwise hard to observe under normal experimental conditions in high-$T_c$ cuprates. Moreo

Eyal Goldmann, Scot R. Renn

We investigate the edge reconstruction phenomenon believed to occur in quantum dots in the quantum Hall regime when the filling fraction is nu < 1. Our approach involves the examination of large dots (< 40 electrons) using a partial diagonalization technique in which the occupancies of the deep interior orbitals are frozen. To interpret the results of this c

Luca Salasnich

We study the Bose-Einstein condensation for a cloud of $^7$Li atoms with attractive nonlocal (finite-range) interaction in a harmonic trap. In addition to the low-density metastable branch, that is present also in the case of local interaction, a new stable branch appears at higher densities. For a large number of atoms, the size of the cloud in the stable h

J. Craig Wheeler

There are hints that nearby Type Ia supernovae may be a little different than those at large redshift. Confidence in the conclusion that there is a cosmological constant and an accelerating Universe thus still requires the hard work of sorting out potential systematic effects. Polarization data show that core-collapse supernovae (Type II and Ib/c) probably d

J. Afonso, B. Mobasher, A. Hopkins, L. Cram

The study of the nature of faint radio sources is of great importance since a significant fraction of these objects is thought to be composed of actively star-forming galaxies. Due to the increased sensitivity of radio telescopes, we are now not only able to catalogue large numbers of these sources in the sub-millijansky regime, but also to start the study o

P. A. Woudt, R. C. Kraan-Korteweg, A. P. Fairall

The nature and extent of the Great Attractor (GA) has been the subject of much debate in the past decade, partly due to the fact that a large fraction of the GA overdensity is hidden by the southern Milky Way. Based on our deep optical galaxy search behind the southern Milky Way and a subsequent redshift survey we discovered that the Norma cluster (ACO 3627)

J. A. Sellwood

A long-standing controversy in studies of spiral structure has concerned the lifetimes of individual spiral patterns. Much theoretical work has sought quasi-stationary spiral modes while N-body simulations have consistently displayed recurrent, short-lived patterns. The simulations manifest a recurrent cycle of true instabilities related to small-scale featu

R. Ehrlich

The features and problems of a speculative model based on the electron neutrino being a tachyon are discussed. The model is consistent with five properties of the cosmic ray spectrum, and it predicts a flux of neutrons in a narrow energy region centered on 4.5 +/- 2.2 x 10^{15} eV.

Scott C. Chapman, Douglas Scott, Charles C. Steidel, Colin Borys

We have carried out targetted sub-mm observations as part of a programme to explore the connection between the rest-frame UV and far-IR properties of star-forming galaxies at high redshift, which is currently poorly understood. On the one hand the Lyman break technique is very effective at selecting z~3 galaxies. On the other hand `blank field&#39; imaging i

S. Krasnikov

The paper has been withdrawn by the author, due to a fatal error. A horse stumbles that has four legs.

D. G. Angelakis, E. Paspalakis, P. L. Knight

We investigate the transient response of a $Λ$-type system with one transition decaying to a modified radiation reservoir with an inverse square-root singular density of modes at threshold, under conditions of transparency. We calculate the time evolution of the linear susceptibility for the probe laser field and show that, depending on the strength of the c

Philippe Jacquod, A. Douglas Stone

We study a generic model of interacting fermions in a finite-sized disordered system. We show that the off-diagonal interaction matrix elements induce density of states fluctuations which generically favor a minimum spin ground state at large interaction amplitude, $U$. This effect competes with the exchange effect which favors large magnetization at large $

Y. Alhassid, Ph. Jacquod, A. Wobst

We introduce a random interaction matrix model (RIMM) for finite-size strongly interacting fermionic systems whose single-particle dynamics is chaotic. The model is applied to Coulomb blockade quantum dots with irregular shape to describe the crossover of the peak spacing distribution from a Wigner-Dyson to a Gaussian-like distribution. The crossover is univ

Boris Kastening, Hagen Kleinert

We present an efficient algorithm for calculating multiloop Feynman integrals perturbatively.

Rodrigo Aros, Mauricio Contreras, Rodrigo Olea, Ricardo Troncoso

A new formula for the conserved charges in 3+1 gravity for spacetimes with local AdS asymptotic geometry is proposed. It is shown that requiring the action to have an extremum for this class of asymptotia sets the boundary term that must be added to the Lagrangian as the Euler density with a fixed weight factor. The resulting action gives rise to the mass an

Gavriel Segre

Paper erroneously re-submitted as duplicte. Readers should look at math-ph/9909004.

G. H. Rawitscher, B. D. Esry, E. Tiesinga, J. P. Burke

Three different numerical techniques for solving a coupled channel Schroedinger equation are compared. This benchmark equation, which describes the collision between two ultracold atoms, consists of two channels, each containing the same diagonal Lennard-Jones potential, one of positive and the other of negative energy. The coupling potential is of an expone

Joel David Hamkins

Introducing unfoldable cardinals last year, Andres Villaveces ingeniously extended the notion of weak compactness to a larger context, thereby producing a large cardinal notion, unfoldability, with some of the feel and flavor of weak compactness but with a greater consistency strength. Specifically, kappa is theta-unfoldable when for any transitive structure

Vaughan F. R. Jones

We introduce a notion of planar algebra, the simplest example of which is a vector space of tensors, closed under planar contractions. A planar algebra with suitable positivity properties produces a finite index subfactor of a II_1 factor, and vice versa.