April 2000 arXiv papers — page 19

Alessandro Fabbri, Diego J. Navarro, Jose Navarro-Salas

The formation of near-extremal Reissner-Nordstrom black holes in the S-wave approximation can be described, near the event horizon, by an effective solvable model. The corresponding one-loop quantum theory remains solvable and allows to follow analytically the evaporation process which is shown to require an infinite amount of time.

Dong Lai

Self-similar solutions provide good descriptions for the gravitational collapse of spherical clouds or stars when the gas obeys a polytropic equation of state, $p=Kρ^γ$ (with $γ\le 4/3$). We study the behaviors of nonradial perturbations in the similarity solutions of Larson, Penston and Yahil, which describe the evolution of the collapsing cloud prior to co

K. H. Andersen, P. Castiglione, A. Mazzino, A. Vulpiani

We show that {\it strong} anomalous diffusion, i.e. $\mean{|x(t)|^q} \sim t^{q ν(q)}$ where $q ν(q)$ is a nonlinear function of $q$, is a generic phenomenon within a class of generalized continuous-time random walks. For such class of systems it is possible to compute analytically nu(2n) where n is an integer number. The presence of strong anomalous diffusio

R. Ocaña, A. Taldenkov, P. Esquinazi, Y. Kopelevich

We have performed high-resolution measurements of the magnetic field (0~T~$ \le B \le 9~$T) and temperature (10 K~$\le T < 140~$K) dependence of the longitudinal and transverse Hall thermal conductivity of a twinned YBa$_{2}$Cu$_{3}$O$_{6.95}$ single crystal. We have used and compared two recently published methods to extract the thermal Hall angle $θ_H(T,B)

Shengjun Wu, Yongde Zhang

We show that not all 4-party pure states are GHZ reducible (i.e., can be generated reversibly from a combination of 2-, 3- and 4-party maximally entangled states by local quantum operations and classical communication asymptotically) through an example, we also present some properties of the relative entropy of entanglement for those 3-party pure states that

M. Hart, P. Jefferies, N. F. Johnson, P. M. Hui

We show analytically how the fluctuations (i.e. standard deviation) in the Minority Game (MG) can be made to decrease below the random coin-toss limit if the agents use more general behavioral strategies. This suppression of the standard deviation results from a cancellation between the actions of a crowd, in which agents act collectively and make the same d

Bastian Bergerhoff, Juergen Reingruber

We propose a nonperturbative scheme for the calculation of thermal damping-rates using exact renormalization group (RG)-equations. Special emphasis is put on the thermal RG where first results for the rate were given in M. Pietroni, Phys. Rev. Lett. 81 (1998), 2424. We point out that in order to obtain a complete result that also reproduces the known perturb

F. Affouard, E. Cochin, R. Decressain, M. Descamps

By means of NMR experiment and MD computer simulation we investigate the dynamical properties of a chloroadamantane orientationally disordered crystal. We find a plastic-plastic dynamical transition at T_x ~ 330 K in the pico-nanosecond regime. It is interpreted as the rotational analogue of the Goldstein crossing temperature between quasi-free diffusion and

J. Barrette, R. Bellwied, S. Bennett, R. Bersch

Directed flow of antiprotons is studied in Au+Au collisions at a beam momentum of 11.5A GeV/c. It is shown that antiproton directed flow is anti-correlated to proton flow. The measured transverse momentum dependence of the antiproton flow is compared with predictions of the RQMD event generator.

A. V. Gulov, V. V. Skalozub

Model independent search for signals of heavy Z&#39; gauge bosons in low-energy four-fermion processes is analyzed. It is shown that the renormalizability of the underlying theory containing Z&#39;, formulated as a scattering in the field of heavy virtual states, can be implemented in specific relations between different processes. Considering the two-Higgs-

K. P. Hart, B. J. van der Steeg

In this paper we show that, when we iteratively add Sacks reals to a model of ZFC we have for every two reals in the extension a continuous function defined in the ground model that maps one of the reals onto the other.

S. Weiss, D. Koelle, J. Mueller, K. Barthel

We analyzed voltage rectification for dc SQUIDs biased with ac current with zero mean value. We demonstrate that the reflection symmetry in the 2-dimensional SQUID potential is broken by an applied flux and with appropriate asymmetries in the dc SQUID. Depending on the type of asymmetry, we obtain a rocking or a simultaneously rocking and flashing ratchet, t

Yong Liu, Utpal Sarkar

Suppose the geometrical explaination to the weak CP phase in quark sector is also valid for neutrinos, the mixing and CP violation in neutrino system are discussed. We find a larger $J_{CP}$ than $3\times 10^{-3}$ implys the large-mixing solution for solar neutrino problem. In case of bi-maximal mixing, we predict relative large CP violation with $J_{CP}$ la

Gael Combe, Jean-Noel Roux

The series of equilibrium states reached by disordered packings of rigid, frictionless discs in two dimensions, under gradually varying stress, are studied by numerical simulations. Statistical properties of trajectories in configuration space are found to be independent of specific assumptions ruling granular dynamics, and determined by geometry only. A mon

Shibusa Yuuichirou

We calculate all of vielbein superfields up to second order in anticommuting coordinates in terms of the component fields of 11-dimensional on-shell supergravity by using `Gauge completion&#39;. This configuration of superspace holds the $κ$-symmetry for supermembrane Lagrangian and represents 11-dimensional on-shell supergravity.

Shengjun Wu, Yongde Zhang

We extend Vedral and Plenio&#39;s theorem (theorem 3 in Phys. Rev. A 57, 1619) to a more general case, and obtain the relative entropy of entanglement for a class of mixed states, this result can also follow from Rains&#39; theorem 9 in Phys. Rev. A 60, 179.

James E. Rhoads, Andrew S. Fruchter

We present near-infrared observations of the counterpart of GRB 000301c. The K&#39; filter (2.1 micron) light curve shows a well-sampled break in the decay slope at t=3.5 days post-burst. The early time slope is very shallow (~ -0.1), while the late time slope is steep (-2.2). Comparison with the optical (R band) light curve shows marginally significant diff

B. Mielnik, L. M. Nieto, O. Rosas-Ortiz

The higher order supersymmetric partners of the Schroedinger&#39;s Hamiltonians can be explicitly constructed by iterating a simple finite difference equation corresponding to the Baecklund transformation. The method can completely replace the Crum determinants. Its limiting, differential case offers some new operational advantages.

D. Salgado, J. L. Sanchez-Gomez

A brief analysis of the compatibility between the quantum jump and the Markov property for quantum systems described by a stochastic evolution scheme is presented.

Stephan Heiss, Stefan Weigert

In Moyal&#39;s formulation of quantum mechanics, a quantum spin s is described in terms of continuous symbols, i.e. by smooth functions on a two-dimensional sphere. Such prescriptions to associate operators with Wigner functions, P- or Q-symbols, are conveniently expressed in terms of operator kernels satisfying the Stratonovich-Weyl postulates. In analogy t

Mari A. Watanabe, Flavio H Fenton, Steven J. Evans, Harold Hastings

Discordant alternans,the phenomenon of 2 separate cardiac tissue locations exhibiting action potential duration (APD) alternans of opposite phase, appears to be a potential mechanism for electrocardiographic T wave alternans, but its initiation mechanism is unknown. We studied behavior of one- and two- dimensional cardiac tissue spatially homogenous in all r

A. W. Thomas, G. Krein

Chiral loop corrections for hadronic properties are considered in a constituent quark model. It is emphasized that the correct implementation of such corrections requires a sum over intermediate hadronic states. The leading non-analytic corrections are very important for baryon magnetic moments and explain the failure of the sum rule $(\mu_{\Sigma^{+}}+2\mu_

S. S. Hsiao, D. H. Lu, Shin Nan Yang

The question of pseudovector versus pseudoscalar coupling schemes for the kaon-hyperon-nucleon interaction is re-examined for the reaction $γp\to K^+ Λ$ in several isobaric models. These models typically include Born terms, $K^*$- and $K_1$-exchange in the t-channel, and a few different combinations of spin-1/2 baryon resonances in the $s$- and $u$-channels.

V. Z. Enolskii, F. Gesztesy, H. Holden

We provide a complete treatment of algebro-geometric solutions of the classical massive Thirring system. In particular, we study Dubrovin-type equations for auxiliary divisors, consider the corresponding algebro-geometric initial value problem, and derive the theta function representations of algebro-geometric solutions of the Thirring system.

Eric Leichtnam, Ryszard Nest, Boris Tsygan

We show that the index of an elliptic Fourier integral operator associated to a contact diffeomorphism $ϕ$ of cosphere bundles of two Riemannian manifolds X and Y is given by $\int_{B^*X}\hat{A}(T^*X)\expθ - \int_{B^*Y}\hat{A}(T^*Y)\expθ$. Here $B^*$ stands for the unit coball bundle and $θ$ is a certain characteristic class depending on the principal symbol

Riccardo Capovilla, Jemal Guven, Efrain Rojas

We describe the dynamics of a relativistic extended object in terms of the geometry of a configuration of constant time. This involves an adaptation of the ADM formulation of canonical general relativity. We apply the formalism to the hamiltonian formulation of a Dirac-Nambu-Goto relativistic extended object in an arbitrary background spacetime.

Steven Corley

In this note we show how Ward identities may be derived for a quantum field theory dual of a string theory using the AdS/CFT correspondence. In particular associated with any gauge symmetry of the bulk supergravity theory there is a corresponding constraint equation. Writing this constraint in Hamilton-Jacobi form gives a generating functional for Ward ident

A. Akhmetshin, Y. Volvovsky

J. F. van Diejen and H. Puschmann have recently shown that the dynamics of zeros of the n-solitonic solutions to the Schrodinger equation with the reflectionless potential is governed by a rational Ruijsenaars-Schneider system. We use the algebraic-geometrical construction of solutions to the Schrodinger equation to generalize this result to the elliptic cas

A. Bassetto, L. Griguolo, F. Vian

We review several aspects of Yang-Mills theory (YMT) in two dimensions, related to its perturbative and topological properties. Consistency between light-front and equal-time formulations is thoroughly discussed.

P. Bantay

Symmetric product orbifolds, i.e. permutation orbifolds of the full symmetric group S_{n} are considered by applying the general techniques of permutation orbifolds. Generating functions for various quantities, e.g. the torus partition functions and the Klein-bottle amplitudes are presented, as well as a simple expression for the discrete torsion coefficient

Ko Furuta, Takeo Inami

We construct noncommutative extension of the Wess-Zumino-Witten (WZW) model and study its ultraviolet property. The β-function of the U(N) noncommutative WZW model resembles that of the ordinary WZW model. The U(1) noncommutative model has also a nontrivial fixed point.

Michal Brhlik

I review the mechanism of electroweak baryogenesis within the framework of a string motivated supersymmetric extension of the Standard Model with large flavor-independent CP-violating phases. Possible implications for the Higgs sector are considered in correlation with the properties of the right-handed stop. I also comment on the compatibility of supersymme

Martin Schroedter, Robert L. Thews, Johann Rafelski

We study quantitatively the formation and evolution of B_c bound states in a space-time domain of deconfined quarks and gluons (quark-gluon plasma, QGP). At the Relativistic Heavy Ion Collider (RHIC) one expects for the first time that typical central collisions will result in multiple pairs of heavy (in this case charmed) quarks. This provides a new mechani

H. G. Dosch, M. Eidemuller, M. Jamin, E. Meggiolaro

Taking the gauge invariant quark correlator as an example, in this work we perform a direct comparison of lattice QCD simulations with the QCD sum rule approach. The quark correlator is first investigated in the framework of QCD sum rules and the correlation length of the quark field is calculated. Comparing the phenomenological part of the sum rule with pre

Guo-Hong Wu

The triangular basis is proposed as an efficient way of analyzing general quark mass matrices. Applying the method to hermitian hierarchical matrices with five texture zeros, analytic predictions for quark mixing can be readily obtained. One unique texture pair is found most favorable with present data. Some remarks are also made concerning parallel textures

M. Frewer, H. J. Rothe

We prove that lattice QCD generates the axial anomaly in the continuum limit under very general conditions on the lattice action, which includes the case of Ginsparg-Wilson fermions. The ingredients going into the proof are gauge invariance, locality of the Dirac operator, absence of fermion doubling, the general form of the lattice Ward identity, and the po

Robert V. Kowalewski, Paul D. Jackson

Deviations between the form of trajectory assumed in a fit to a set of measurements and the actual form of the trajectory can give rise to sequential correlations in the residuals from the fit. These correlations can provide a more powerful goodness-of-fit test than that based on the minimum chi-square from a least squares fit. The use of this additional inf

L3 Collaboration

A search for a Higgs boson decaying into invisible particles is performed using the data collected at LEP by the L3 experiment at centre-of-mass energies of 183 GeV and 189 GeV. The integrated luminosities are respectively 55.3 pb^-1 and 176.4 pb^-1. The observed candidates are consistent with the expectations from Standard Model processes. In the hypothesis

Ricardo Garcia-Salcedo, Nora Breton

We present a model for an inhomogeneous and anisotropic early universe filled with a nonlinear electromagnetic field of Born-Infeld (BI) type. The effects of the BI field are compared with the linear case (Maxwell). Since the curvature invaria nts are well behaved then we conjecture that our model does not present an initial big bang singularity. The existen

Jiri Bicak

Contents: 1) Introduction and a few excursions [A word on the role of explicit solutions in other parts of physics and astrophysics. Einstein&#39;s field equations. &#34;Just so&#34; notes on the simplest solutions: The Minkowski, de Sitter and anti-de Sitter spacetimes. On the interpretation and characterization of metrics. The choice of solutions. The outl

Krzysztof R. Apt, Andrea Schaerf

In (Apt et al, TOPLAS 1998) we introduced the imperative programming language Alma-0 that supports declarative programming. In this paper we illustrate the hybrid programming style of Alma-0 by means of various examples that complement those presented in (Apt et al, TOPLAS 1998). The presented Alma-0 programs illustrate the versatility of the language and sh

N. Harrison, L. Balicas, J. S. Brooks, M. Tokumoto

We present the results of magnetotransport and magnetic torque measurements on the alpha-(BEDT-TTF)2KHg(SCN)4 charge-transfer salt within the high magnetic field phase, in magnetic fields extending to 33 T and temperatures as low as 27 mK. While the high magnetic field phase (at fields greater than ~ 23 T) is expected, on theoretical grounds, to be either a

S. M. Komirenko, K. W. Kim, M. A. Stroscio, M. Dutta

In order to justify applicability of the standard approach of perturbation theory for the description of transport phenomena in wide-band polar semiconductors with strong electron-phonon interactions, we have compared dependences of energy losses to the lattice on the electron drift velocity obtained for different materials in the frameworks of (a) a perturb

M. Huthmann, J. A. G. Orza, R. Brito

The time dependence of deviations from the Gaussian state in a freely cooling homogeneous system of smooth inelastically colliding spheres is investigated by kinetic theory. We determine the full time dependence of the coefficients of an expansion around the Gaussian state in Generalized Laguerre polynomials. Approximating this system of equations to sixth o

Richard T Giles, Feodor V Kusmartsev

We investigate the roto-breathers recently observed in experiments on Josephson ladders subjected to a uniform transverse bias current. We describe the switching mechanism in which the number of rotating junctions increases. In the region close to switching we find that frequency locking, period doubling, quasi-periodic behaviour and symmetry breaking all oc

P. Mendels, A. Keren, L. Limot, M. Mekata

We present the first Ga(4f) NMR study of the Cr susceptibility in the archetype of Kagome based frustrated antiferromagnets, SrCr$_{8}$Ga$_{4}$O$_{19}$. Our major finding is that the susceptibility of the frustrated lattice goes through a maximum around 50 K. Our data also supports the existence of paramagnetic ``clusters&#39;&#39; of spins, responsible for

M. R. Falvo, J. Steele, A. Buldum, J. D. Schall

We report, through experimental observations and computer simulations, that atomic lattice interlocking can determine whether an object rolls or slides on a surface. We have quantitatively manipulated carbon nanotubes (CNTs) on a variety of substrates with an atomic force microscope (AFM) and observe rolling to occur only on graphite. We measure the forces w

C. Grimaldi, P. Ryser, S. Straessler

Despite a large amount of data and numerous theoretical proposals, the microscopic mechanism of transport in thick film resistors remains unclear. However, recent low temperature measurements point toward a possible variable range hopping mechanism of transport. Here we examine how such a mechanism affects the gauge factor of thick film resistors. We find th

A. K. Zvezdin

New macroscopic quantum interference effects in the behavior of the antiferromagnetic nanoclusters under action of a swept magnetic field are predicted and theoretically investigated, namely : oscillations of the magnetic susceptibility of nanocluster similar to the electron Bloch oscillations in crystal and the corresponding Stark ladder-like resonances in

A. E. Carlsson, S. Zapata

A method for generating angular forces around $σ$-bonded transition metal ions is generalized to treat $π$-bonded configurations. The theoretical approach is based on an analysis of a ligand-field Hamiltonian based on the moments of the electron state distribution. The functional forms that are obtained involve a modification of the usual expression of the b

S. Moss de Oliveira, Domingos Alves, J. S. Sa Martins

The idea of this review is to connect the different models of evolution to those of biological ageing through Darwin&#39;s theory. We start with the Eigen model of quasispecies for microevolution, then introduce the Bak-Sneppen model for macroevolution and, finally, present the Penna model for biological ageing and some of its most important results. We also

J. Chovan, N. Papanicolaou

An effective field theory is derived that describes the low-frequency spin dynamics in the low-temperature orthorombic phase of La_2CuO_4. Restricted to a single CuO_2 layer the effective theory is a simple generalization of the relativistic nonlinear sigma model to include all spin interactions allowed by symmetry. Incorporating a weak interlayer interactio

Beom Jun Kim

We investigate numerically the resistive transition in the two-dimensional XY gauge glass model. The resistively-shunted junction dynamics subject to the fluctuating twist boundary condition is used and the linear resistances in the absence of an external current at various system sizes are computed. Through the use of the standard finite-size scaling method

Noelle Pottier, Alain Mauger

A time-domain formulation of the equilibrium quantum fluctuation-dissipation theorem (FDT) in the whole range of temperatures is presented. In the classical limit, the FDT establishes a proportionality relation between the dissipative part of the linear response function and the derivative of the corresponding equilibrium correlation function. At zero temper

A. I. Olemskoi, A. V. Khomenko

The theory of a jamming transition is proposed for the homogeneous car-following model within the framework of Lorenz scheme. We represent a jamming transition as a result of the spontaneous deviations of headway and velocity that is caused by the acceleration/braking rate to be higher than the critical value. The stationary values of headway and velocity de

Toshiaki Iitaka, Toshikazu Ebisuzaki

We extend the recently proposed order-N algorithms (cond-mat/9703224) for calculating linear- and nonlinear-response functions in time domain to the systems described by nonorthonormal basis sets.

A. B. Kolton, D. Dominguez, C. J. Olson, N. Gronbech-Jensen

We study a 3D model of driven vortices in weakly coupled layered superconductors with strong pinning. Above the critical force $F_c$, we find a plastic flow regime in which pancakes in different layers are uncoupled, corresponding to a pancake gas. At a higher $F$, there is an ``smectic flow&#39;&#39; regime with short-range interlayer order, corresponding t

B. Spivak, A. Zyuzin, M. Hruska

We consider a system of superconducting grains embedded in a normal metal. At zero temperature this system exhibits a quantum superconductor-normal metal phase transition. This transition can take place at arbitrarily large conductance of the normal metal.

O. P. Sushkov

We consider a magnetic impurity in a spin liquid state of a magnetic system which is close to the quantum phase transition to the magnetically ordered state. There is similarity between this problem and the Kondo problem. We derive the impurity Green&#39;s function, consider renormalizations of the magnetic moments of the impurity, calculate critical indexes

Gregory M. Braverman, Sergey A. Gredeskul, Yshai Avishai

Persistent scaling behavior of magnetization in layered high $T_c$ superconductors with short--range columnar defects is explained within the Ginzburg Landau theory. In the weak field region, the scaling function differs from that of a clean sample and both the critical and crossing temperatures are renormalized due to defects. In the strong field region, de

P. D. Ditlevsen

Reduced wavenumber models of turbulence, shell models, show cascade processes and anomalous scaling of correlators which might be analogous to what is observed in Navier-Stokes (N-S) turbulence. The scaling properties of the shell models depends on the specific symmetries and invariants of the models. A new shell model is investigated. It is argued that this

H. K. C. Yee

The dependence of star formation rate on galaxian environment is a key issue in the understanding of galaxy formation and evolution. However, the study of this subject is complex and observationally challenging. This paper reviews some of the current results, drawing mostly from recent large redshift surveys such the LCRS, the MORPH collaboration, and the CN

C. Alard

The large number of microlensing events discovered towards the Galactic Bulge bears the promise to reconstruct the stellar mass function. The more interesting issue concerning the mass function is certainly to probe its low mass end. However due to the source confusion, even if the distribution and the kinematics of the lenses are known, the estimation of th

Leonid Malyshkin, Jeremy Goodman

We study the stochastic coagulation equation using simplified models and efficient Monte Carlo simulations. It is known that (i) runaway growth occurs if the two-body coalescence kernel rises faster than linearly in the mass of the heavier particle; and (ii) for such kernels, runaway is instantaneous in the limit that the number of particles tends to infinit

H. J. Witt, S. Mao, C. R. Keeton

We study gravitational lens time delays for a general family of lensing potentials, which includes the popular singular isothermal elliptical potential and singular isothermal elliptical density distribution but allows general angular structure. Using a novel approach, we show that the time delay can be cast in a very simple form, depending only on the obser

C. S. Reynolds, M. A. Nowak, P. R. Maloney

We present a deep X-ray observation of the low-luminosity active galactic nucleus in NGC4258 (M106) using ASCA. The soft X-ray spectrum <2keV is dominated by thermal emission from optically-thin plasma with kT~0.5keV. The hard X-ray emission is clearly due to a power-law component with photon index Gamma=1.8 absorbed by a column density of N_H=8x10^22/cm^2.

Bing Zhang, Alice K. Harding

We propose a unified picture of high magnetic field radio pulsars and magnetars by arguing that they are all rotating high-field neutron stars, but have different orientations of their magnetic axes with respective to their rotation axes. In strong magnetic fields where photon splitting suppresses pair creation near the surface, the high-field pulsars can ha

M. Le Louarn, N. Hubin, M. Sarazin, A. Tokovinin

The performance of an adaptive optics (AO) system on a 100m diameter ground based telescope working in the visible range of the spectrum is computed using an analytical approach. The target Strehl ratio of 60% is achieved at 0.5um with a limiting magnitude of the AO guide source near R~10, at the cost of an extremely low sky coverage. To alleviate this probl

Diego F. Torres, S. Capozziello, G. Lambiase

We explore whether supermassive non-baryonic stars (in particular boson, mini-boson and non-topological soliton stars) might be at the center of some galaxies, with special attention to the Milky Way. We analyze, from a dynamical point of view, what current observational data show, concluding that they are compatible with a single supermassive object without

B. R. Parodi, A. Saha, A. Sandage, G. A. Tammann

A sample of 35 SNe Ia with good to excellent photometry in B and V, minimum internal absorption, and 1200 < v < \approx 30000 km/s is compiled from the literature. As far as their spectra are known they are all Branch-normal. For 29 of the SNe Ia also peak magnitudes in I are known. The SNe Ia have uniform colors at maximum, i.e. <B-V>=-0.012 mag (sigma=0.05

Toshitaka Tatsumi

Spontaneous magnetization of quark liquid is examined on the analogy with that in electron gas. It is pointed out that quark liquid has potential to be ferromagnetic at rather low densities, around nuclear saturation density. Somme comments are given as for implications on magnetars.

W. Collmar, S. Benlloch, J. E. Grove, R. C. Hartman

We report first observational results of multifrequency campaigns on the prominent Virgo blazars 3C 273 and 3C 279 which were carried out in January and February 1999. Both blazars are detected from radio to gamma-ray energies. We present the measured X- to gamma-ray spectra of both sources, and for 3C 279 we compare the 1999 broad-band (radio to gamma-ray)

T. Kitayama, Y. Tajiri, M. Umemura, H. Susa

To elucidate the effects of the UV background radiation on the collapse of pregalactic clouds, we implement a radiation-hydrodynamical calculation, combining one-dimensional spherical hydrodynamics with an accurate treatment of the radiative transfer of ionizing photons. Both absorption and scattering of UV photons are explicitly taken into account. It turns

T. Rauscher, F. -K. Thielemann

Theoretical reaction rates in the temperature range 0.01*10^9<=T[K]<=10.*10^9 are calculated in the statistical model (Hauser-Feshbach formalism) for targets with 10<=Z<=83 (Ne to Bi) and for a mass range reaching the neutron and proton driplines. Reactions considered are (n,gamma), (n,p), (n,alpha), (p,gamma), (p,alpha),(alpha,gamma), and their inverse reac

Brad M. S. Hansen

Planet formation is accompanied by the formation of comet clouds. In systems where planets migrate on rapid timescales, the diffusive evolution of comet orbits may stall, resulting in a comet cloud intermediate between a flattened Kuiper Belt and a spherical Oort cloud. These `failed Oort clouds&#39; may provide a `smoking gun&#39;, indicating that planetary

David W. Hogg

In very crowded fields, the modulation of the background by the sea of unresolved faint sources induces centroid shifts. The errors increase with the number of sources per beam. Even the most optimistic simulations of imaging data show that position errors can become severe (on the order of the beam size) at flux levels at which images contain 1/50 to 1/15 s

Igor F. Herbut

The Ginzburg-Landau-Wilson theory that describes the disordered Fermi liquid - d-wave superconductor phase transition at zero temperature is derived at weak coupling. The theory represents an interacting dissipative system of bosonic Cooper pairs in an effective random potential. I show that there exists a wide crossover regime in the theory controlled by a

Rouzbeh Allahverdi

We present a detailed examination of thermalization after inflation for perturbative inflaton decay. Different interactions among particles in the plasma of inflaton decay products are considered and it will be shown that 2 -> 2 scatterings and particle decay are the important ones. We show that thermalization occurs after decays dominate scatterings, and th

A. Muecke, R. J. Protheroe

(abr.) The spectral energy distribution (SED) of blazars typically has a double-humped appearance usually interpreted in terms of synchrotron self-Compton models. In proton blazar models, the SED is instead explained in terms of acceleration of protons and subsequent cascading. We discuss a variation of the Synchrotron Proton Blazar model, first proposed by

Robin J. Spivey

A supermassive rotating toroidal black hole (TBH) is proposed as the fundamental structure of quasars and other jet-producing active galactic nuclei. Rotating protogalaxies gather matter from the central gaseous region leading to the birth of massive toroidal stars whose internal nuclear reactions proceed very rapidly. Once the nuclear fuel is spent, gravita

A. Lagoyannis, F. Auger, A. Musumarra, N. Alamanos

Proton elastic scattering and inelastic scattering to the first excited state of 6He have been measured over a wide angular range using a 40.9A MeV 6He beam. The data have been analyzed with a fully microscopic model of proton-nucleus scattering using 6He wave functions generated from large space shell model calculations. The inelastic scattering data show a

Carlos Barcelo, Matt Visser

Branes are ubiquitous elements of any low-energy limit of string theory. We point out that negative tension branes violate all the standard energy conditions of the higher-dimensional spacetime they are embedded in; this opens the door to very peculiar solutions of the higher-dimensional Einstein equations. Building upon the (3+1)-dimensional implementation

M. Benayoun, L. DelBuono, Ph. Leruste, H. B. O&#39;Connell

We examine the mechanisms producing departures from ideal mixing for vector mesons within the context of the Hidden Local Symmetry (HLS) model. We show that kaon loop transitions between the ideal combinations of the $ω$ and $ϕ$ mesons necessitate a field transformation in order to get the mass eigenstates. It is shown that this transformation is close to a

A. Banfi, G. Marchesini, Yu. L. Dokshitzer, G. Zanderighi

Perturbative QCD analysis is presented of the cumulative out-of-plane momentum distribution in the near-to-planar e+e- annihilation events, K_out << Q. In this kinematical region multiple gluon radiation effects become essential. They are resummed with the single-logarithmic accuracy, which programme includes the 2-loop treatment of the basic radiation and m

M. Pohlen, R. -J. Dettmar, R. Luetticke, U. Schwarzkopf

We present detailed three-dimensional modelling of the stellar luminosity distribution for the disks of 31 relatively nearby (<= 110 Mpc) edge-on spiral galaxies. In contrast to most of the standard methods available in the literature we take into account the full three-dimensional information of the disk. We minimize the difference between the observed 2D-i

Cecile Appert, Ludger Santen

We study boundary induced phase transitions in a driven lattice gas exhibiting metastability. The phase diagram for open systems, parameterized by the input and output rates, consists of two regions corresponding to the free flow and jammed phase. Both have been entirely characterized. The microscopic states in the high density phase are shown to have an int

M. E. Gomez, G. Lazarides, C. Pallis

The minimal supersymmetric standard model with universal boundary conditions and &#34;asymptotic&#34; Yukawa unification is considered. The full one-loop effective potential for radiative electroweak symmetry breaking as well as the one-loop corrections to the charged Higgs boson, b-quark and tau lepton masses are included. The CP-even Higgs boson masses are

Alice Sinatra, Yvan Castin, Carlos Lobo

We propose an efficient stochastic method to implement numerically the Bogolubov approach to study finite-temperature Bose-Einstein condensates. Our method is based on the Wigner representation of the density matrix describing the non condensed modes and a Brownian motion simulation to sample the Wigner distribution at thermal equilibrium. Allowing to sample

S. Burdin, A. Georges, D. R. Grempel

It is shown that the large-N approach yields two energy scales for the Kondo lattice model. The single-impurity Kondo temperature, $T_K$, signals the onset of local singlet formation, while Fermi liquid coherence sets in only below a lower scale, $T^{\star}$. At low conduction electron density $n_c$ (&#34;exhaustion&#34; limit), the ratio $T^{\star}/T_K$ is

P. O. Fedichev, G. V. Shlyapnikov

We describe a dramatic decrease of the critical velocity in elongated cylindrical Bose-Einstein condensates which originates from the non-uniform character of the radial density profile. We discuss this mechanism with respect to recent measurements at MIT.

R. Ketzmerick, L. Hufnagel, F. Steinbach, M. Weiss

In mixed systems, besides regular and chaotic states, there are states supported by the chaotic region mainly living in the vicinity of the hierarchy of regular islands. We show that the fraction of these hierarchical states scales as $\hbar^{-α}$ and relate the exponent $α=1-1/γ$ to the decay of the classical staying probability $P(t)\sim t^{-γ}$. This is n

E. E. Donets, A. Pashnev, V. O. Rivelles, D. Sorokin

The dynamics of an N=4 spinning particle in a curved background is described using the N=4 superfield formalism. The $SU(2)_{local}\times SU(2)_{global}$ N=4 superconformal symmetry of the particle action requires the background to be a real &#34;Kähler-like&#34; manifold whose metric is generated by a sigma-model superpotential. The anti-de-Sitter spaces ar

Yoav Achiman, Carsten Merten

Right-handed (RH) rotations do not play a role in the Standard Model, and only the differences of the LH mixing angles are involved in ${\bf V}_{\scr \textrm{CKM}}$. This leads to the huge freedom in the fermionic mass matrices. However, that is no more true in extensions of the Standard Model. For example in GUTs large RH rotations of the quarks can be rela

Hamid Kharraziha

A new model for the exchange of two gluons between the virtual photon and the proton, in non-diffractive deeply inelastic electron-proton scattering, is developed and studied. This model relies on a perturbative calculation, previously applied to diffraction, and a general result from Regge theory. As a first application of the model, we study corrections to

A. M. Badalian, B. L. G. Bakker

From a fit to the experimental data on the $b\bar{b}$ fine structure, the two-loop coupling constant is extracted. For the 1P state the fitted value is $α_s(μ_1) = 0.33 \pm 0.01(exp)\pm 0.02 (th)$ at the scale $μ_1 = 1.8 \pm 0.1$ GeV, which corresponds to the QCD constant $Λ^{(4)}(2-loop) = 338 \pm 30$ MeV (n_f = 4) and $α_s(M_Z) = 0.119 \pm 0.002. For the 2

Daniel Khomskii

An orbital ordering, often observed in Mott insulators with orbital degeneracy, is usually supposed to disappear with doping, e.g. in the ferromagnetic metallic phase of manganites. We propose that the orbital ordering of a novel type may exist in such situation: there may occur ferro orbital ordering of complex orbitals (linear superposition of basic orbita

Sin Kyu Kang, C. S. Kim, J. D. Kim

Neutrino oscillations as solutions of the solar neutrino problems and the atmospheric neutrino deficits may restrict neutrino mass squared differences and mixing angles in three-neutrino mixing scheme. Currently we have several solutions depending on the interpretations of the solar neutrino problems. Combining the neutrino oscillation solutions and a mass m

S. Heinrichs, J. Rottler, Ph. Maass

We develop a theory for nucleation on top of islands in epitaxial growth based on the derivation of lifetimes and rates governing individual microscopic processes. These processes are strongly affected by the additional step edge barrier E_S for descending atoms. If the dissociation times of unstable clusters can be neglected, the theory predicts that for sm

Robert Braun, W. Butler Burton

Growing evidence supports the suggestion that the compact high-velocity clouds of HI (CHVCs) are located throughout the Local Group and continue to fuel galactic evolution. Recent distance estimates to individual objects lie in the range 150-850 kpc, implying an HI mass range of 10^5.7 to 10^7.2 M_Sun together with sizes ranging from 2-12 kpc, while the aver

Marek Biskup, Christian Borgs, Jennifer T. Chayes, Logan J. Kleinwaks

We present a general, rigorous theory of Lee-Yang zeros for models with first-order phase transitions that admit convergent contour expansions. We derive formulas for the positions and the density of the zeros. In particular, we show that for models without symmetry, the curves on which the zeros lie are generically not circles, and can have topologically no