May 1997 arXiv papers — page 9

M. Staats, U. Nowak, K. D. Usadel

Diluted Ising antiferromagnets in a homogenous magnetic field have a disordered phase for sufficiently large values of the field and for low temperatures. Here, the system is in a domain state with a broad size-distribution of fractal domains. We study the relaxation dynamics of this domain state after removing the external field for two and three dimensions

Yuli V. Nazarov, D. V. Averin

We study the current drag in the system of two electrostatically coupled finite 1D electron channels. We present the perturbation theory results along with the results for two non-perturbative regimes. It is shown that the drag may become absolute, that is, the currents in the channels are equal in a finite window of the bias voltages.

Sebastian Eggert, Ann E. Mattsson, Jari M. Kinaret

We present explicit expressions for the correlation functions of interacting fermions in one dimension which are valid for arbitrary system sizes and temperatures. The result applies to a number of very different strongly correlated systems, including mesoscopic quantum wires, quantum Hall edges, spin chains and quasi-one-dimensional metals. It is for exampl

C. T. Shih, Y. C. Chen, T. K. Lee

The boundary of phase separation of the two-dimensional t-J model is investigated by the power-Lanczos method and Maxwell construction. The method is similar to a variational approach and it determines the lower bound of the phase separation boundary with $J_c/t=0.6\pm 0.1$ in the limit $n_e\sim 1$. In the physical interesting regime of high T_c superconduct

Werner Winiwarter, Yahiko Kambayashi

In this paper we present first results from a comparative study. Its aim is to test the feasibility of different inductive learning techniques to perform the automatic acquisition of linguistic knowledge within a natural language database interface. In our interface architecture the machine learning module replaces an elaborate semantic analysis component. T

K. Hurley, E. Costa, M. Feroci, F. Frontera

The gamma-ray burst of 1997 February 28 was localized using the arrival-time analysis method with the Ulysses, BeppoSAX, and WIND spacecraft. The result is a plus-or-minus 31.5 arcsec (3 sigma) wide annulus of possible arrival directions which intersects both the position of the burst determined independently by the SAX Wide Field Camera, and the position of

J. C. Wheeler, Peter Hoeflich

Physical models of Type Ia supernovae (SN Ia) that do not depend on secondary calibrators have indicated that the Hubble Constant must be about 65 km/s/Mpc for well over a decade with the range of uncertainty shrinking with the sophistication of the models. This estimate is in good agreement with those based on HST observations of Cepheid variables and with

C. J. Horowitz, Gang Li

Supernovae provide a unique opportunity for large scale parity violation because they are dominated by neutrinos. We calculate the parity violating asymmetry A of neutrino emission in a strong magnetic field. We assume the neutrinos elastically scatter many times from slightly polarized neutrons. Because of multple interactions, A grows with the optical thic

Angelica de Oliveira-Costa, George F. Smoot, Alexei A. Starobinsky

We present a new data analysis method to study rectangular T^3 ``small universes" with one or two of its dimensions significantly smaller than the present horizon (which we refer to as T^1- and T^2-models, respectively). We find that the 4 year COBE/DMR data set a lower limit on the smallest cell size for T^1- and T^2-models of 3000h^{-1} Mpc, at 95% con

Boudewijn F. Roukema, David Valls-Gabaud

Several recent measurements have been made of the angular correlation function $w(θ,m)$ of faint galaxies in deep surveys (e.g., Hubble Deep Field, HDF). Are the measured correlations indicative of gravitational growth of primordial perturbations or of the relationship between galaxies and (dark matter dominated) galaxy haloes? A first step in answering this

M. Montuori, F. Sylos Labini, A. Amici

We analyze subsamples of Abell and ACO cluster catalogs, in order to study the spatial properties of the large scale matter distribution. The subsamples analyzed are estimated to be nearly complete and are the standard ones used in the correlation analysis by various authors. The statistical analysis of cluster correlations is performed without any assumptio

P. Schneider, L. van Waerbeke, Y. Mellier, B. Jain

We present evidence for a coherent shear signal in a field containing the z=1.2 radio-source PKS1508-05. Since there were no intervening mass concentrations known before targeting this field, we interpret this signal as due to weak lensing by large-scale structure. This result is the outcome of a re-analysis of the observations of Fort et al. (1996) in the f

Adi Nusser, Jörg M. Colberg

We show that the equations of motion governing the evolution of a collisionless gravitating system of particles in an expanding universe can be cast in a form which is almost independent of the cosmological density parameter, $Ω$, and the cosmological constant, $Λ$. The new equations are expressed in terms of a time variable $τ\equiv \ln D$, where $D$ is the

S. L. Lumsden, C. A. Collins, R. C. Nichol, V. R. Eke

We have re-examined the nature of the cluster galaxy luminosity function using the data from the Edinburgh-Durham Southern Galaxy Catalogue and the Edinburgh-Milano Redshift Survey. We derive a best fit luminosity function over the range M(bj)=-18 to -21, for a composite sample of 22 of the richer clusters that has M*=-20.16+/-0.02 and alpha=-1.22+/-0.04. Th

H. Oberhummer, A. N. Ivanov, N. I. Troitskaya, M. Faber

The relativistic field theory model of the deuteron suggested by us previously is applied to the calculation of the reaction rate of the low-energy two-proton fusion p + p -> D + e+ + nu. The theoretical prediction of the reaction rate obtained is 2.9 times larger than given by the potential approach. This leads to a strong suppression of the high energy sol

Jeffrey P. Gardner, Neal Katz, David H. Weinberg, Lars Hernquist

We calculate the number of damped Lyman-alpha absorbers expected in various popular cosmological models as a function of redshift and compare our predictions with observed abundances. The Press-Schechter formalism is used to obtain the distribution of halos with circular velocity in different cosmologies, and we calibrate the relation between circular veloci

Jozef H. Przytycki, Adam S. Sikora

This paper gives insight into intriguing connections between two apparently unrelated theories: the theory of skein modules of 3-manifolds and the theory of representations of groups into special linear groups of 2 by 2 matrices. Let R be a ring with an invertible element A. For any 3-manifold M one can assign an R-module called the Kauffman bracket skein mo

I. Chepelev, A. A. Tseytlin

We compute long-distance interaction potentials between certain 1/2 and 1/4 supersymmetric D-brane configurations of type IIB theory, demonstrating detailed agreement between classical supergravity and one-loop instanton matrix model results. This confirms the interpretation of D-branes as described by classical matrix model backgrounds as being `populated&#

John M. Pierre

We consider eight-brane configurations in M(atrix) theory and compute their interaction potentials with gravitons, membranes, and four-branes. We compare these results with the interactions of D8-branes with D0-branes, D2-branes, and D4-branes in IIA string theory. We find agreement between the two approaches for eight-brane interactions with two-branes and

H. S. Egawa, N. Tsuda

A model of simplicial quantum gravity in three dimensions is investigated numerically based on the technique of the dynamical triangulation (DT). We are concerned with the surfaces appearing on boundaries (i.e., sections) of three-dimensional DT manifold with $S^{3}$ topology. A new scaling behavior of genus distributions of boundary surfaces is found.Furthe

D. G. Polyakov, K. V. Samokhin

We argue that the finite temperature dynamics of the integer quantum Hall system is governed by two independent length scales. The consistent scaling description of the transition makes crucial use of two temperature critical exponents, reflecting the interplay between charging effects and interaction-induced dephasing. Experimental implications of the two-s

Washington Taylor

A Yang-Mills solution is constructed on T^6 which corresponds to a brane configuration composed purely of 0-branes and 6-branes. This configuration breaks all supersymmetries and has an energy greater than the sum of the energies of its components; nonetheless, the configuration is stable classically, at least to quadratic order. An analogous construction is

Jiannis Pachos

Within the framework of a local expansion of the logarithm of the O(N) sigma-model vacuum functional, valid for slowly varying fields, the modified Virasoro algebra is studied. The operator-like central charge term is given, up to second order, for a general functional.

G. Wanders

Constraints on the parameters in the one- and two-loop pion-pion scattering amplitudes of standard chiral perturbation theory are obtained from explicitly crossing-symmetric sum rules. These constraints are based on a matching of the chiral amplitudes and the physical amplitudes at the symmetry point of the Mandelstam plane. The integrals over absorptive par

Nathan Seiberg

We survey the various field theories with 16 real supercharges. The most widely known theory in this class is the N=4 theory in four dimensions. The moduli space of vacua of these theories are described and the physics at the singularities of the moduli spaces are studied.

E. Gaztanaga, P. Fosalba, E. Elizalde

We compare the latest results from CMB experiments at scales around $l_e \sim 150$ over different parts of the sky to test the hypothesis that they are drawn from a Gaussian distribution, as is usually assumed. Using both the diagonal and the full covariance $χ^2$ test, we compare the data with different sets of strategies and find in all cases incompatibili

A. C. Quillen, T. E. Pickering

We present near-Infrared images of low surface brightness galaxies: H band images of UGC 6614 and F568-6 (Malin 2). The H band images show spiral structure so we are confident that we are seeing the galaxy disks as well as the central bulges. The optical-IR colors of these galaxies, $R-H = 2.2\pm 0.2$, $B-H = 3.5-4.2$, are extremely red and are similar to th

Wataru Kawasaki, Kazuhiro Shimasaku, Mamoru Doi, Sadanori Okamura

We describe an objective and automated method for detecting clusters of galaxies from optical imaging data. This method is a variant of the so-called `matched-filter' technique pioneered by Postman et al. (1996). With simultaneous use of positions and apparent magnitudes of galaxies, this method can, not only find cluster candidates, but also estimate th

Alon E. Faraggi, Marco Matone

We postulate that physical states are equivalent under coordinate transformations. We then implement this equivalence principle first in the case of one-dimensional stationary systems showing that it leads to the quantum analogue of the Hamilton-Jacobi equation which in turn implies the Schroedinger equation. In this context the Planck constant plays the rol

M. Yu. Konstantinov

The hypothesis about possible existence of new class of particles able to travel faster then light as a source of dark matter, recently formulated by L. Gonzalez-Mesters, is analyzed. To this end the general geometrical model for several kinds of matter with different Lorentziann structures coexisting on the same manifold is introduced and the local energy d

Suresh Govindarajan

We consider M(atrix) theory compactifications to seven dimensions with eight unbroken supersymmetries. We conjecture that both M(atrix) theory on K3 and Heterotic M(atrix) theory on T^3 are described by the same 5+1 dimensional theory with N=2 supersymmetry which is broken to N=1 by the base space. The emergence of the extra dimension follows from a recent r

Suresh G. Mishra, P. A. Sreeram

The signature for a non-Fermi liquid behavior near a quantum phase transition has been observed in thermal and transport properties of many metallic systems at low temperatures. In the present work we consider specific examples of itinerant ferromagnet as well as antiferromagnet in the limit of vanishing transition temperature. The temperature variation of s

I. Schienbein

O(α) QED radiative corrections to neutral current deep inelastic production of heavy quarks are calculated in the leading log approximation and compared with the corresponding corrections assuming a massless charm parton. Besides the inclusive case, corrections to the semi-inclusive d^3σ/dx dy dz and the effect of z-cuts are studied. In the latter case, the

Helge Frauenkron, Ugo Bastolla, Erwin Gerstner, Peter Grassberger

We demonstrate that the recently proposed pruned-enriched Rosenbluth method (P. Grassberger, Phys. Rev. E 56 (1997) 3682) leads to extremely efficient algorithms for the folding of simple model proteins. We test them on several models for lattice heteropolymers, and compare to published Monte Carlo studies. In all cases our algorithms are faster than all pre

Kikuo Harigaya

Ring torsion effects on optical excitation properties in poly(para-phenylene) (PPP) and polyaniline (PAN) are investigated by the intermediate exciton formalism. Long-range excitons are characterized, and the long-range component of the oscillator strengths is calculated. We find that ring torsions affect the long-range excitons in PAN more easily than in PP

S. C. Woon

The method analytic continuation of operators acting integer n-times to complex s-times (hep-th/9707206) is applied to an operator that generates Bernoulli numbers B_n (Math. Mag. 70(1), 51 (1997)). B_n and Bernoulli polynomials B_n(s) are analytic continued to B(s) and B_s(z). A new formula for the Riemann zeta function zeta(s) in terms of nested series of

I. E. Lagaris, A. Likas, D. I. Fotiadis

In a previous article we have shown how one can employ Artificial Neural Networks (ANNs) in order to solve non-homogeneous ordinary and partial differential equations. In the present work we consider the solution of eigenvalue problems for differential and integrodifferential operators, using ANNs. We start by considering the Schrödinger equation for the Mor

S. Wallentowitz, R. L. de Matos Filho, W. Vogel

We propose a method for measuring entangled vibronic quantum states of a trapped atom. It is based on the nonlinear dynamics of the system that appears by resonantly driving a weak electronic transition. The proposed technique allows the direct sampling of a Wigner-function matrix, displaying all knowable information on the quantum correlations of the motion

S. Wallentowitz, W. Vogel

Raman-type laser excitation of a trapped atom allows one to realize the quantum mechanical counterpart of phenomena of nonlinear optics, such as Kerr-type nonlinearities, parametric amplification, and multi-mode mixing. Additionally, huge nonlinearities emerge from the interference of the atomic wave function with the laser waves. They lead to a partitioning

R. Vilela Mendes, J. A. Dente

A problem of great concern in aviation and submarine propulsion is the control of the boundary layer and, in particular, the methods to extend the laminar region as a means to decrease noise and fuel consumption. In this paper we study the flow of air along an airfoil when a layer of ionized gas and a longitudinal electric field are created in the boundary l

R. M. Santilli

In this note we outline the history of q-deformations; indicate their physical shortcomings; suggest their apparent resolution via an invariant formulation based on a new mathematics of genotopic type; and point out their expected physical significance once formulated in an invariant way.

Y. H. Ng, J. F. McCann

Total cross sections for electron capture are calculated for collisions of fast protons and alpha-particles with atomic hydrogen. The distorted- wave impulse approximation is applied over the energy range 10-1500 keV/u. State-selective results are given for the 1s, 2s and 2p levels. Both the 'post' and 'prior' forms of the model are calculate

I. Keller, A. Oron, P. Z. Bar-Yoseph

A weakly nonlinear model for two-dimensional Faraday waves over infinite depth is derived and studied. Sideband instability of monochromatic standing waves as well as non-monochromatic solutions are studied analytically. Persistent irregular regimes are found numerically.

K. Saito, M. Oka, T. Suzuki

The meson(K and $π$) exchange currents for the hypernuclear magnetic moments are calculated using the effective Lagrangian method. The seagull diagram, the mesonic diagram and the $Σ^0$-excitation diagram are considered. The $Λ$-N exchange magnetic moments for the ${}^5_ΛHe$, ${}^6_ΛHe$ and ${}^6_ΛLi$ are calculated employing the harmonic oscillator shell mo

M. Brack, S. M. Reimann, M. Sieber

We give a semiclassical interpretation of the mass asymmetry in the fission of heavy nuclei. Using only a few classical periodic orbits and a cavity model for the nuclear mean field, we reproduce the onset of left-right asymmetric shapes at the fission isomer minimum and the correct topology of the deformation energy surface in the region of the outer fissio

K. J. Eskola

The role of minijet production as initial conditions for QGP production at $τ\sim 0.1 fm/c$ in nuclear collisions at the LHC and RHIC energies is discussed.

E. Friedman, A. Gal, J. Mares

Total and reaction cross sections are derived self consistently from the attenuation cross sections measured in transmission experiments at the AGS for K^+ on Li^6, C, Si and Ca in the momentum range of 500-700 MeV/c by using a V_{opt}=t_{eff}(rho)rho optical potential. Self consistency requires, for the KN in-medium t matrix, that Im t_{eff}(rho) increases

Thomas R. Hemmert, Barry R. Holstein, Germar Knoechlein, Stefan Scherer

We are studying the electron scattering process e p to e' p' gamma in order to obtain information on the genuine virtual Compton scattering (VCS) process gamma^* N to gamma N. In addition to the two kinematical variables of real Compton scattering, e.g. the scattering angle theta and the energy omega' of the outgoing photon, the invariant amplitu

Saharon Shelah

The Kalikow problem for a pair (lambda, kappa) of cardinal numbers, lambda > kappa (in particular kappa =2) is whether we can map the family of omega --sequences from lambda to the family of omega --sequences from kappa in a very continuous manner. Namely, we demand that for eta, nu in lambda^omega we have: eta, nu are almost equal if and only if their image

Andreas Blass, Yuri Gurevich, Saharon Shelah

Turing machines define polynomial time (PTime) on strings but cannot deal with structures like graphs directly, and there is no known, easily computable string encoding of isomorphism classes of structures. Is there a computation model whose machines do not distinguish between isomorphic structures and compute exactly PTime properties? This question can be r

Saharon Shelah

Our main result is that possibly some non-null set of reals cannot be divided to uncountably many non-null sets. We deal also with a non-null set of reals, the graph of any function from it is null and deal with our iterations somewhat more generally.

Renata Kallosh

The action of supersymmetric Born-Infeld theory (D-9-brane in a Lorentz covariant static gauge) has a geometric form of the Volkov-Akulov-type. The first non-linearly realized supersymmetry can be made manifest, the second world-volume supersymmetry is not manifest. We also study the analogous 2 supersymmetries of the quadratic action of the covariantly quan

F. Englert

I discuss features required for preserving unitarity in black hole decay and concepts underlying such a perspective. Unitarity requires that correlations extend on the scale of the horizon. I show, in a toy model inspired by string theories, that such correlations can indeed arise. The model suggests that, after a time of order 4M ln M following the onset of

Gernot Akemann, Jan C. Plefka

A supereigenvalue model with purely positive bosonic eigenvalues is presented and solved by considering its superloop equations. This model represents the supersymmetric generalization of the complex one matrix model, in analogy to the relation between the supereigenvalue and the hermitian one matrix model. Closed expressions for all planar multi-superloop c

Pierre van Baal

We review recent results for the low-lying glueball spectrum on the three-sphere in intermediate volumes that incorporate instanton effects. The latter are implemented through boundary conditions on the fundamental domain obtained by minimising the norm of the gauge field along the gauge orbit. Non-perturbative corrections due to the boundary conditions in f

Yoichi Kazama

As a step toward satisfactory understanding of the quantum dynamics of Dirichlet \break (D-) particles, the amplitude for the basic process describing the scattering of two quantized D-particles is computed in bosonic string theory. The calucluation is performed and cross-checked using three different methods, namely, (i) path integral, (ii) boundary state,

F. Toppan

It is pointed out that affine Lie algebras appear to be the natural mathematical structure underlying the notion of integrability for two-dimensional systems. Their role in the construction and classification of 2D integrable systems is discussed. The super- symmetric case will be particularly enphasized. The fundamental examples will be outlined.

Michael Birkel, Subir Sarkar

It has been suggested by Bartlett and Hall that our universe may have the critical density in baryons by virtue of specific interactions with a `shadow' world. We show that this possibility is severely constrained by primordial nucleosynthesis, stellar evolution and the thermalization of the cosmic microwave background. In particular, recent observations

G. Moultaka

We report on how a straightforward (albeit technically involved) analytic study of the 1-loop effective potential in the Minimal Supersymmetric Standard Model, modifies the usual electroweak symmetry breaking conditions involving $\tan β$ and the other free parameters of the model. The study implies new constraints which (in contrast with the existing ones l

Heinz Sorge, Edward Shuryak, Ismail Zahed

We argue that a decrease of the chiral scalar meson mass is responsible for re-creation of $Ψ'$ from $J/Ψ$ in ultrarelativistic nucleus-nucleus collisions. This causes the charmonium yields to freeze out at temperatures close to the chiral symmetry restoration temperature $T_c$. As a result $Ψ'/Ψ$ may serve as a thermometer for $T_c$ itself. Results

P. M. Ferreira, I. Jack, D. R. T. Jones, C. G. North

We present calculations of the leading and $O(1/N_f)$ terms in a large-$N_f$ expansion of the $β$-functions and anomalous dimensions for various supersymmetric gauge theories, including supersymmetric QCD. In the case of supersymmetric QCD, we show that our $O(1/N_f)$ approximation displays an infra-red fixed point in the conformal window $3N_c/2 < N_f < 3N_

S. Fajfer, P. Singer

We present a detailed analysis of the $D \to V γ$ transitions, using a model which combines heavy quark effective theory and the chiral Lagrangian approach and includes symmetry breaking. We notice that in addition to the previously considered s - channel annihilation and t - channel W - exchange, there is a long distance penguin - like $ c \to u γ$ contribu

M. Yu. Kopysov, Yu. E. Pokrovsky

We discuss a possible new manifestation of the formation of an initial nonequilibrium flux tube stage in high energy heavy ion collisions. It is shown that a strong asymmetry in particle distributions around axes of hard-transverse jets takes place due to a large difference between longitudinal and transverse forces acting on the hardly scattered quarks or g

She-Sheng Xue

We discuss the necessity of a right-handed Weyl neutrino due to the vector-like phenomenon of the regularized Standard Model. It is shown that this right-handed neutrino is decoupled from low energies as a free particle, and Dirac neutrino masses are very small. We suggest gauge-invariant couplings between down quarks and charged leptons so that charged lept

V. Morénas, A. Le Yaouanc, L. Oliver, O. Pène

The slope of the Isgur-Wise function for ground state mesons is evaluated for the heavy mass limit of quark models à la Bakamjian-Thomas, which has been previously discussed by us in general terms. A full calculation in various spectroscopic models with relativistic kinetic energy gives a rather stable result $ρ^2 \approx 1$, much lower than previous estimat

S. P. Klevansky, A. Ogura, P. Rehberg, J. Hüfner

Chiral symmetry is an important aspect of QCD. Modelling this via the Nambu-Jona-Lasinio model, we construct a complete relativistic transport theory for quarks and mesons. The collision integral is analysed in a systematic 1/N_c approximation, and via this, it is shown that one can naturally incorporate mesonic degrees of freedom plus the hadronization of q

S. A. Caveny, P. M. Stevenson

The recent calculation of the four-loop beta function in QCD provides further evidence that the Banks-Zaks expansion in 16half-n_f is sufficiently well behaved to be useful even for n_f=2 light flavours. This expansion inherently predicts &#34;freezing&#34; of the QCD couplant at low energies as a perturbative effect. We consider the e+e- and Bjorken-sum-rul

The E852 Collaboration

The $ηπ^{-}$ system has been studied in the reaction $π^{-} p \to ηπ^{-} p$ at 18 GeV/c. A large asymmetry in the angular distribution is observed indicating interference between L-even and L-odd partial waves. The $a_{2}(1320)$ is observed in the $J^{PC}$ = $2^{++}$ wave, as is a broad enhancement between 1.2 and 1.6 GeV/c^{2} in the $J^{PC} = 1^{-+}$ wave.

D0 Collaboration, B. Abbott

We present limits on anomalous WWZ and WW-gamma couplings from a search for WW and WZ production in p-bar p collisions at sqrt(s)=1.8 TeV. We use p-bar p -> e-nu jjX events recorded with the D0 detector at the Fermilab Tevatron Collider during the 1992-1995 run. The data sample corresponds to an integrated luminosity of 96.0+-5.1 pb^(-1). Assuming identical

CLEO Collaboration, J. P. Alexander et al

Using the CLEO II detector at the $e^+e^-$ storage ring CESR, we have determined the Michel parameters $ρ$, $ξ$, and $δ$ in $τ^\mp \to l^\mpν\barν$ decay as well as the tau neutrino helicity parameter $h_{ν_τ}$ in $τ^\mp \to π^\mpπ^0ν$ decay. From a data sample of $3.02\times 10^6$ tau pairs produced at $\sqrt{s}=10.6 GeV$, using events of the topology $e^+e

J. Colding, N. K. Nielsen, Y. Verbin

The explicit relationship is determined between the interior properties of a static cylindrical matter distribution and the metric of the exterior space-time according to Einstein gravity for space-time dimensionality larger or equal to four. This is achieved through use of a coordinate system isotropic in the transverse coordinates. As a corollary, similar

Giampiero Esposito, Alexander Yu. Kamenshchik, Gennaro Miele

Quantum cosmology may restrict the class of gauge models which unify electroweak and strong interactions. In particular, if one studies the normalizability criterion for the one-loop wave function of the universe in a de Sitter background one finds that the interaction of inflaton and matter fields, jointly with the request of normalizability at one-loop ord

C. Barrabès, G. F. Bressange, P. A. Hogan

The outward-pointing principal null direction of the Schwarzschild Riemann tensor is null hypersurface-forming. If the Schwarzschild mass spontaneously jumps across one such hypersurface then the hypersurface is the history of an outgoing light-like shell. The outward-- pointing principal null direction of the Kerr Riemann tensor is asymptotically (in the ne

Jose M. Montanero, Andres Santos, Mirim Lee, James W. Dufty

The stability of idealized shear flow at long wavelengths is studied in detail. A hydrodynamic analysis at the level of the Navier-Stokes equation for small shear rates is given to identify the origin and universality of an instability at any finite shear rate for sufficiently long wavelength perturbations. The analysis is extended to larger shear rates usin

P. L. Krapivsky, E. Ben-Naim

We study the domain number and size distributions in the one-dimensional Ising and $q$-state Potts models subject to zero-temperature Glauber dynamics. The survival probability of a domain, $S(t)\sim t^{-ψ}$, and an unreacted domain, $Q_1(t)\sim t^{-δ}$, are characterized by two independent nonrtrivial exponents. For the Ising case, we find $ψ=0.126$ and $δ=

H. Rosner, R. Hayn, J. Schulenburg

Band structure calculations for Ba_2Cu_3O_4Cl_2 within the local density approximation (LDA) are presented. The investigated compound is similar to the antiferromagnetic parent compounds of cuprate superconductors but contains additional Cu_B atoms in the planes. Within the LDA, metallic behavior is found with two bands crossing the Fermi surface (FS). These

Kirone Mallick, Sven Sandow

We study the one dimensional partially asymmetric simple exclusion process (ASEP) with open boundaries, that describes a system of hard-core particles hopping stochastically on a chain coupled to reservoirs at both ends. Derrida, Evans, Hakim and Pasquier [J. Phys. A 26, 1493 (1993)] have shown that the stationary probability distribution of this model can b

A. K. Kienappel, M. A. Moore

The equilibrium dynamics of a thin film type II superconductor with spherical geometry are investigated numerically in a simulation based on the lowest Landau level approximation to the time-dependent Ginzburg-Landau equation. Both the static and time-dependent density-density correlation functions of the superconducting order parameter have been investigate

K. Kundu, B. C. Gupta

We study the formation of stationary localized states using the discrete nonlinear Schrödinger equation in a Cayley tree with connectivity $K$. Two cases, namely, a dimeric power law nonlinear impurity and a fully nonlinear system are considered. We introduce a transformation which reduces the Cayley tree into an one dimensional chain with a bond defect. The

Kohji Nakamura, Hideo Hasegawa, Tamio Oguchi, Kazuhisa Sueoka

First-principles calculations have been performed for the exchange interaction and exchange force between two magnetic Fe(100) thin films. It is shown that the magnitude of the calculated exchange force is of the order of $10^{-9} $N at $d/a < 1$ and of the order of $10^{-10} $N at $1 < d/a < 1.5$, where $d$ denotes the distance between surfaces of the two t

Masanori Kohno, Minoru Takahashi

The magnetization process of the spin-1/2 antiferromagnetic XXZ model with Ising-like anisotropy in the ground state is investigated. We show numerically that the Ising-like XXZ models on square and cubic lattices show a first-order phase transition at some critical magnetic field. We estimate the value of the critical field and the magnetization jump on the

Hideo Yoshioka, Yoshikazu Suzumura

We examine spin-Peierls systems in the presence of spin defects which are introduced by replacing magnetic ions $Cu^{2+}$ with non-magnetic ones $Zn^{2+}$ in $CuGeO_3$. By using the action for the bosonized Hamiltonian, it is shown directly that the antiferromagnetic state induced by the spin defects coexists with the spin-Peierls states. Further the doping

Boldizsar Janko, Jiri Maly, K. Levin

We demonstrate how resonant pair scattering of correlated electrons above T_c can give rise to pseudogap behavior. This resonance in the scattering T-matrix appears for superconducting interactions of intermediate strength, within the framework of a simple fermionic model. It is associated with a splitting of the single peak in the spectral function into a p

Carlton M. Caves, Ruediger Schack

A source of unpredictability is equivalent to a source of information: unpredictability means not knowing which of a set of alternatives is the actual one; determining the actual alternative yields information. The degree of unpredictability is neatly quantified by the information measure introduced by Shannon. This perspective is applied to three kinds of u

Charles F. Gammie, Robert Popham

We write down and solve equations describing steady state, optically thin, advection-dominated accretion onto a Kerr black hole. The mean flow, described by the relativistic fluid equations, is axisymmetric and vertically averaged. The effect of turbulence in the flow is represented by a viscous shear stress. Our treatment differs in several important ways f

H. R. Schmitt, A. L. Kinney, D. Calzetti, T. Storchi-Bergmann

We present the results of an extensive literature search of multiwavelength data for a sample of 59 galaxies, consisting of 26 Starbursts, 15 Seyfert 2&#39;s, 5 LINER&#39;s, 6 normal spirals and 7 normal elliptical galaxies. The data include soft X-ray fluxes, ultraviolet and optical spectra, near, mid/far infrared photometry and radio measurements, selected

Chung-Pei Ma, Edmund Bertschinger, Lars Hernquist, David H. Weinberg

Any viable cosmological model must produce enough structure at early epochs to explain the amount of gas associated with high-redshift damped Ly$α$ systems. We study the evolution of damped Ly$α$ systems at redshifts $z\ge 2$ in cold dark matter (CDM) and cold+hot dark matter (CDM+HDM) models using both N-body and hydrodynamic simulations. Our approach incor

Sukyoung Yi, Pierre Demarque, Yong-Cheol Kim

We consider the origin of the UV bright phase of metal-rich helium-burning stars, the slow blue phase (SBP), that was predicted by various earlier works. Based on improved physics including OPAL opacities, we confirm the existence of the SBP. In addition to our grid of evolutionary tracks, we provide an analytical understanding of the main characteristics of

Pascal Chardonnet, Jean Orloff, Pierre Salati

The discovery of a single anti-helium nucleus in the cosmic ray flux would definitely point toward the existence of stars and even of entire galaxies made of anti-matter. The presence of anti-nuclei in cosmic rays has actually profound implications on the fundamental question of the baryon asymmetry of the universe. It is therefore crucial to determine the a

Lucia Fania, Giorgio Ottaviani

Arrondo, Sols and De Cataldo proved that there are only finitely many families of codimension two subvarieties not of general type in the smooth quadric of dimension $n+2$ for $n\ge 2 $, $n\neq 4$. In this paper we drop the assumption $n\neq 4$ from the previous result (obviously the assumption $n\ge 2$ cannot be removed).

T. E. Browder, A. Datta, X. -G. He, S. Pakvasa

We consider the possibility of observing CP violation in quasi-inclusive decays of the type $B^-\to K^- X$, $B^-\to K^{*-} X$, $\bar B^0\to K^- X$ and $\bar B^0\to K^{*-} X$, where $X$ does not contain strange quarks. We present estimates of rates and asymmetries for these decays in the Standard Model and comment on the experimental feasibility of observing

Edi Halyo

We examine five dimensional extreme black holes with three charges in the matrix model. We build configurations of the 5+1 super Yang-Mills theory which correspond to black holes with transverse momentum charge. We calculate their mass and entropy from the super Yang-Mills theory and find that they match the semi-classical black hole results. We extend our r

Paul S. Aspinwall, David R. Morrison

The map between the moduli space of F-theory (or type II string) compactifications and heterotic string compactifications can be considerably simplified by using &#34;stable degenerations&#34;. We discuss how this method applies to both the E8 x E8 and the Spin(32)/Z2 heterotic string. As a simple application of this method we derive some basic properties of

J. Michael Owen, David H. Weinberg, August E. Evrard, Lars Hernquist

We analyze hierarchical structure formation based on scale-free initial conditions in an Einstein-de Sitter universe, including a baryonic component. We present three independent, smoothed particle hydrodynamics (SPH) simulations, performed with two different SPH codes (TreeSPH and P3MSPH) at two resolutions. Each simulation is based upon identical initial c

Peter E. Haagensen, Kasper Olsen, Ricardo Schiappa

Starting from a consistency requirement between T-duality symmetry and renormalization group flows, the two-loop metric beta function is found for a d=2 bosonic sigma model on a generic, torsionless background. The result is obtained without Feynman diagram calculations, and represents further evidence that duality symmetry severely constrains renormalizatio

John Cardy

Using methods of conformal field theory, we conjecture an exact form for the probability that n distinct clusters span a large rectangle or open cylinder of aspect ratio k, in the limit when k is large.

Gianpiero Mangano

We propose a path integral formulation of noncommutative generalizations of spacetime manifold in even dimensions, characterized by a length scale $λ_P$. The commutative case is obtained in the limit $λ_P=0$.

Kenji Hotta

In recent years, Susskind, Thorlacius and Uglum have proposed a model for strings near a black hole horizon in order to represent the quantum mechanical entropy of the black hole and to resolve the information loss problem. However, this model is insufficient because they did not consider the metric modification due to massive strings and did not explain how

Kenji Hotta, Keiji Kikkawa, Hiroshi Kunitomo

Brandenberger and Vafa have proposed the string cosmological model based on T-duality. In this model, they took the toroidal target space and introduced the new position \tilde{x} conjugate to the winding mode, in addition to the position x conjugate to the momentum mode. In this way they can describe a universe larger than the string scale with the coordina

G. Martinelli, G. C. Rossi, C. T. Sachrajda, S. Sharpe

We propose a method to improve lattice operators composed of Wilson fermions which allows the removal of all corrections of $O(a)$, including those proportional to the quark mass, leaving only errors of $O(a^2)$. The method exploits the fact that chiral symmetry is restored at short distances. By imposing this requirement on correlation functions of improved