March 1999 arXiv papers — page 8

J. Ricardo G. de Mendonca

We carried out a finite-size scaling analysis of the restricted solid-on-solid version of a recently introduced growth model that exhibits a roughening transition accompanied by spontaneous symmetry breaking. The dynamic critical exponent of the model was calculated and found to be consistent with the universality class of the directed percolation process in

Pieter Kok, Samuel L. Braunstein

We study the experimental realisation of quantum teleportation as performed by Bouwmeester {\em et al}. [Nature {\bf 390}, 575 (1997)] and the adjustments to it suggested by Braunstein and Kimble [Nature {\bf 394}, 841 (1998)]. These suggestions include the employment of a detector cascade and a relative slow-down of one of the two down-converters. We show t

S. Fajfer, J. Zupan

We consider the scalar form factor in the weak current matrix element <P K| j_μ|0>, P =π,η,η&#39;. It obtains the contributions from the scalar meson resonance K^*_0(1430) and from the scalar projection of the vector meson K^*(892) resonance. We analyze decay amplitudes of the Cabibbo suppressed decays D->K P, P =π,η,η&#39; using the factorization approach.

Michele Pasquini, Maurizio Serva

The dynamics of prices in financial markets has been studied intensively both experimentally (data analysis) and theoretically (models). Nevertheless, a complete stochastic characterization of volatility is still lacking. What it is well known is that absolute returns have memory on a long time range, this phenomenon is known as clustering of volatility. In

J. Dukelsky, G. Sierra

We apply the DMRG method to the BCS pairing Hamiltonian which describes ultrasmall superconducting grains. Our version of the DMRG uses the particle (hole) states around the Fermi level as the system block (environment). We observe a smooth logarithmic-like crossover between the few electron regime and the BCS-bulk regime.

B. Ziaja

The analysis of intermittent data is improved. The standard method of recovering the history of a particle cascade is proved in general not to reproduce the structure of the true cascade. The recovering corrections to the standard method are proposed and tested in the framework of multiplicative cascading models.

Shyamoli Chaudhuri

See hep-th/9907179.

J. Magnin, H. R. Christiansen

We study the $bar{d} - \bar{u}$ asymmetry of the proton in a model approach in which hadronic fluctuations of the nucleon are generated through gluon splitting and recombination mechanisms. Within this framework, it is shown that the \ud asymmetry of the proton is consistently described by including only nucleon fluctuations to $|πN>$ and $|πΔ>$ bound states

Andreas Jaster

Starting from the ordered state, we investigate the short-time behaviour of the hard-disk model. For the positional order, we determine the critical exponents eta and z from the dynamic relaxation of the order parameter and the cumulant with molecular dynamics simulations. The results are compared with previous Monte Carlo (MC) simulations. The bond orientat

C. Bourrely, J. Soffer, Tai Tsun Wu

We show that the rising total cross section $\sigma(\gamma\gamma \to hadrons)$ recently observed by the L3 and OPAL Collaborations at LEP are fully consistent with the impact-picture for high-energy scattering. The impact picture is then used to predict this total cross section at higher energies. These experimental results confirm once more the success of t

Monika Randhawa, V. Bhatnagar, P. S. Gill, M. Gupta

Texture specific quark mass matrices which are hermitian and hierarchical are examined in detail . In the case of texture 6 zeros matrices, out of sixteen possibilities examined by us, none is able to fit the low energy data (LED), for example, $V_{us} = 0.2196 \pm 0.0023$, $V_{cb} = 0.0395 \pm 0.0017$, $\frac{V_{ub}}{V_{cb}} = 0.08 \pm 0.02$, $V_{td}$ lies

Sergey Barannikov

The predictions of the Mirror Symmetry are extended in dimensions n>3 and are proven for projective complete intersections Calabi-Yau varieties. Precisely, we prove that the total collection of rational Gromov-Witten invariants of such variety can be expressed in terms of certain invariants of a new generalization of variation of Hodge structures attached to

Anjan S. Joshipura, Sudhir K. Vempati

Neutrino mass spectrum is reanalyzed in supersymmetric models with explicit trilinear $R$ violation. Models in this category are argued to provide simultaneous solution to the solar and atmospheric neutrino anomalies. It is shown specifically that large mixing and hierarchical masses needed for the vacuum solution of neutrino anomalies arise naturally in the

A. Gashi, E. Matsinos, G. C. Oades, G. Rasche

We calculate the electromagnetic corrections to the isospin invariant mixing angle and to the two eigenphases for the $s$-, $p_{1/2}$- and $p_{3/2}$-partial waves for $π^- p$ elastic and charge exchange scattering. These corrections have to be applied to the nuclear quantities in order to obtain the two hadronic phase shifts for each partial wave. The calcul

Theodora Ioannidou, Paul Sutcliffe

Recently Jarvis has proved a correspondence between SU(N) monopoles and rational maps of the Riemann sphere into flag manifolds. Furthermore, he has outlined a construction to obtain the monopole fields from the rational map. In this paper we examine this construction in some detail and provide explicit examples for spherically symmetric SU(N) monopoles with

E. O. Iltan

We study the Electric Dipole moment of b quark in the general two Higgs Doublet model (model III) and three Higgs Doublet model with O(2) symmetry in the Higgs sector. We analyse the dependency of this quantity to the new phase coming from the complex Yukawa couplings and masses of charged and neutral Higgs bosons. We see that the Electric Dipole moment of b

Prasanta Das, Pankaj Jain

We study the $SU(3)_L\otimes U(1)_X$ extension of the Standard model with a strong U(1) coupling. We argue that current experiments limit this coupling to be relatively large. The model is dynamically broken to the Standard $SU(2)_L \otimes U(1)$ model at the scale of a few TeV with all the extra gauge bosons and the exotic quarks acquiring masses much large

Changhyun Ahn, Hoil Kim

We study toric singularities of the form of $\C^4/\Ga$ for finite abelian groups $\Ga \subset SU(4)$. In particular, we consider the simplest case $\Ga=\Z_2 \times \Z_2 \times \Z_2$ and find explicitly charge matrices for partial resolutions of this orbifold by extending the method by Morrison and Plesser. We obtain three kinds of algebraic equations, $z_1 z

Ramchander R. Sastry

The quantum field theory of extended objects is employed to address the hitherto nonrenormalizable Pauli interaction. This is achieved by quantizing the Dirac field using the infinite dimensional generalization of the extended object formulation. The order $α$ contribution to the anomalous magnetic moment of the electron (and of the muon) arising from the Pa

P. Rozmej, R. Arvieu

The dynamics of wave packets in a relativistic Dirac oscillator is compared to that of the Jaynes-Cummings model. The strong spin-orbit coupling of the Dirac oscillator produces the entanglement of the spin with the orbital motion similar to what is observed in the model of quantum optics. The collapses and revivals of the spin which result extend to a relat

L. Stodolsky

We discuss fluctuations in the measurement process and how these fluctuations are related to the dissipational parameter characterising quantum damping or decoherence. On the example of the measuring current of the variable-barrier or QPC problem we show there is an extra noise or fluctuation connected with the possible different outcomes of a measurement. T

A. Piwinski

The lifetime of a stored beam due to the Touschek effect is calculated for arbitrary ratios of beam height to beam width. A variation of the beam envelopes is taken into account, i.e. the derivatives of the horizontal and vertical amplitude functions and dispersions are included. The calculation is done for arbitrary energies in the rest frame of the collidi

A. V. Gorbatyuk, F. -J. Niedernostheide

Semiconductor $p^+ - p^- - n - p^+ - n^{++}$ structures with large junction and contact areas are treated as 1 \times 2-dimensional active media, in which self-organized pattern formation can be expected. The local bistable behavior of the structures may emanate from two different mechanisms both governed by a nonlinear current feedback-loop between the elec

David Carlton

We wish to give a new proof of one of the main results of Atkin and Lehner. Their theory depends, among other things, on a theorem characterizing forms in S_k(Gamma_0(N)) whose Fourier coefficients satisfy a certain vanishing condition. Our proof involves rephrasing this vanishing condition in terms of representation theory; this, together with an elementary

M. Dokuchaev, R. Exel, P. Piccione

The partial group algebra of a group G over a field K, denoted by K_{par}(G), is the algebra whose representations correspond to the partial representations of G over K-vector spaces. In this paper we study the structure of the partial group algebra K_{par}(G), where G is a finite group. In particular, given two finite abelian groups G_1 and G_2, we prove th

H. Albuquerque, S. Majid

Recently we have reformulated the octonions as quasissociative algebras (quasialgebras) living in a symmetric monoidal category. In this note we provide further examples of quasialgebras, namely ones where the nonassociativity is induced by a Z_n-grading and a nontrivial 3-cocycle

William Beckner

Complexity of geometric symmetry for differential operators with mixed homogeniety is examined here. Sharp Sobolev estimates are calculated for the Grushin operator in low dimensions using hyperbolic symmetry and conformal geometry.

A. M. Voldman, N. I. Vulpe

The new necessary and sufficient affine invariant conditions for the existence and for determining the number of centers for general quadratic system are pointed out. These conditions correspond to the partition of 12-dimensional coefficient space of indicated system with respect to the number and the multiplicity of its finite critical points.

Alexander V. Karabegov

The description of all deformation quantizations with separation of variables on a Kaehler manifold obtained in our earlier paper is used to identify the Fedosov star-product of Wick type constructed by M. Bordemann and S. Waldmann. This star-product is shown to be the one with separation of variables which corresponds to the trivial deformation of the Kaehl

Yutaka Hosotani, Ryuichi Nakayama

Simple derivation of the Hamilton-Jacobi equation for bosonic strings and p-branes is given. The motion of classical strings and p-branes is described by two and p+1 local fields, respectively. A variety of local field equations which reduce to the Hamilton-Jacobi equation in the classical limit are given. They are essentially nonlinear, having no linear ter

Vijay Balasubramanian, Per Kraus

Anti-de Sitter (AdS) space can be foliated by a family of nested surfaces homeomorphic to the boundary of the space. We propose a holographic correspondence between theories living on each surface in the foliation and quantum gravity in the enclosed volume. The flow of observables between our ``interior&#39;&#39; theories is described by a renormalization gr

Mohsen Alishahiha, Andreas Brandhuber, Yaron Oz

We consider Type 0B D3-branes placed at conical singularities and analyze in detail the conifold singularity. We study the non supersymmetric gauge theories on their worldvolume and their conjectured dual gravity descriptions. In the ultraviolet the solutions exhibit a logarithmic running of the gauge coupling. In the infrared we find confining solutions and

Maciej Slusarczyk

Domain wall - type solution with oscillating thickness in a real, scalar field model is investigated with the help of a polynomial approximation. We propose a simple extension of the polynomial approximation method. In this approach we calculate higher order corrections to the planar domain wall solution, find that the domain wall with oscillating thickness

Yuji Ohta

This note reviews the progress on the low energy dynamics of N=2 supersymmetric Yang-Mills theories after the works of Seiberg and Witten. Specifically, the theory of prepotential for non-specialists is reviewed.

R Delbourgo

A summary of the successes of and obstacles to the gauge technique (a non-perturbative method of solving Dyson-Schwinger equations in gauge theories) is given, as well as an outline of how progress may be achieved in this field.

Jin Young Kim, H. W. Lee, Y. S. Myung

We calculate the absorption cross section by studying the spin--dependent wave equation in three-dimensional anti-de Sitter space(AdS$_3$). Here the AdS/CFT correspondence is used. It turns out that the new gauge bosons coupled to (2,0) and (0,2) operators on the boundary at infinity receive logarithmic corrections. This shows that the gauge bosons may play

David Dooling, Kyungsik Kang

We perform an analysis of general quark mass matrices in the general nearest neighbor interaction form. Excellent agreement with experiment is realized with this general texture, which is neither hermitian nor real-symmetric. We then propose a new class of quark mass matrices that contain no additional parameters other than the quark masses themselves, and t

William J. Marciano

Various precision determinations of the Fermi constant are compared. Included are muon and (leptonic) tau decays as well as indirect prescriptions employing $α, m_Z, m_W, \ssthwmzms, Γ(Z\to\ell^+\ell^-)$, and $Γ(Z \to ν\bar ν)$ as input. Their good agreement tests the standard model at the $\pm 0.1%$ level and provides stringent constraints on new physics. T

Jens Erler

We perform a global analysis of electroweak precision measurements to find constraints on physics beyond the Standard Model. In particular, we discuss oblique parameters, which are useful to constrain additional matter fields, as well as extra $Z$ bosons, and supersymmetry. We also summarize the present information on the Higgs boson mass.

Alex Pomarol, Riccardo Rattazzi

We discuss a recently proposed scenario where the sparticle masses are purely mediated by gravity through the superconformal anomaly. This scenario elegantly evades the supersymmetric flavor problem since soft masses, like the anomaly, are not directly sensitive to ultraviolet physics. However, its minimal incarnation fails by predicting tachyonic sleptons.

Dan Pirjol

In the absence of the QCD penguin contributions a measurement of the time-dependent asymmetry in the decay $B^0(t)\to π^+π^-$ gives directly the weak angle $α$. Several bounds have been proposed in the literature on the magnitude of the penguin effects on this determination, the prototype of which is the isospin bound of Grossman and Quinn. It is pointed out

S. V. Molodtsov, A. M. Snigirev, G. M. Zinovjev

The phonon-like excitations of (anti)-instanton ($\bar II$) liquid due to adiabatic variations of vacuum wave functions are studied in this paper. The kinetic energy term is found and the proper effective Lagrangian for such excitations is evaluated. The properties of their spectrum, while corresponding masses are defined by $Λ_{QCD}$, are investigated.

J. Gasser, G. Wanders

The Roy equation in the single channel case is a nonlinear, singular integral equation for the phase shift in the low-energy region. We first investigate the infinitesimal neighborhood of a given solution, and then present explicit expressions for amplitudes that satisfy the nonlinear equation exactly. These amplitudes contain free parameters that render the

F. M. Steffens, W. Melnitchouk, A. W. Thomas

A next-to-leading order analysis of inelastic electroproduction of charm is performed using an interpolating scheme which maps smoothly onto massless QCD evolution at large Q^2 and photon-gluon fusion at small Q^2. In contrast with earlier analyses, this scheme allows the inclusion of quark and target mass effects and heavy quark thresholds, as well as possi

M. Kirchbach

The key assumption used recently by Feldmann, Kroll and Stich [Phys.Rev. D58, 114006 (1998)] that the decay constants f_η, and f_η&#39; of the respective eta and eta &#39; mesons in the quark flavor basis follow the pattern of strange and non--strange quarkonia mixing in their wave functions, is reproduced in identifying the non-isotriplet part of the strong

S. Catani, M. L. Mangano, P. Nason, C. Oleari

We compute the effects of soft-gluon resummation, at the next-to-leading-logarithmic level, in the fixed-target hadroproduction cross section for prompt photons. We find in general that the corrections to the fixed next-to-leading-order results are large for large renormalization scales, and small for small scales. This leads to a significant reduction of th

D. V. Shirkov

A &#34;natural&#34; model for the QCD invariant (running) coupling, free of the IR singularity, is proposed. It is based upon the hypothesis of finite gluon mass $ m_{gl}$ existence and, technically, uses an accurate treating of threshold behavior of Feynman diagram contribution. The model correlates with the unitarity condition. Quantitative estimate, perfo

Maria Teresa Dova, John Swain, Lucas Taylor

We analyse the sensitivities of exclusive one-prong tau branching fractions to: the tau neutrino mass; its mixing with a fourth generation neutrino; the weak charged current magnetic and electric dipole moments of the tau; and the Michel parameter $η$. Quantitative constraints are derived from current experimental data and the future constraints derivable fr

G. S. Sharov, V. P. Petrov

For the string baryon model &#34;triangle&#34; the initial-boundary value problem is stated and solved in general. This problem implies defining a classical motion of the system on the base of given initial position and initial velocities of string points. The presented solution reduces the initial-boundary value problem for the considered model to the syste

P Boyle

We present an investigation of a gauge invariant smearing technique that allows the construction of smearing functions with arbitrary radial behaviour, by foresaking the space filling nature of traditional smearing techniques. This is applied to both heavy-heavy, heavy-light, and light-light systems with one particular choice of radial ``wavefunction&#39;&#3

Gregory S. Mitchell

The experiment E155 at SLAC measured the spin structure functions g_1 and g_2 of the proton and deuteron. The experiment used deep inelastic scattering of 48.3 GeV longitudinally polarized electrons incident on polarized solid ^{15}NH_3 and ^{6}LiD targets. The data taken by three independent spectrometers covered a kinematic range of 0.014 < x < 0.9 and 1 (

Y. A. Kulchitsky, V. B. Vinogradov

The detailed experimental information about the electron and pion responses, the electron energy resolution and the e/h ratio as a function of incident energy E, impact point Z and incidence angle $Θ$ of the Module-0 of the iron-scintillator barrel hadron calorimeter with the longitudinal tile configuration is presented. The results are based on the electron

ALEPH Collaboration

The production of W+W- pairs is analysed in a data sample collected by ALEPH at a mean centre-of-mass energy of 182.7 GeV, corresponding to an integrated luminosity of 57 pb-1. Cross sections are given for different topologies of W decays into leptons or hadrons. Under Standard Model assumptions for the W-pair production and decay, the W-pair cross section i

Y. A. Kulchitsky

The lateral and longitudinal profiles of the hadronic showers detected by iron-scintillator tile hadron calorimeter with longitudinal tile configuration have been investigated. The results are based on 100 GeV pion beam data. Due to the beam scan provided many different beam impact locations with cells it is succeeded to obtain detailed picture of transverse

Y. A. Kulchitsky

The hadronic shower longitudinal and lateral leakages and its effect on the pion response and energy resolution of iron-scintillator barrel hadron prototype calorimeter with longitudinal tile configuration with a thickness of 9.4 nuclear interaction lengths have been investigated. The results are based on 100 GeV pion beam data at incidence angle $Θ= 10^o$ a

Y. A. Kulchitsky

The detailed information about electron response, electron energy resolution and e/h ratio as a function of incident energy E, impact point Z and incidence angle $Θ$ of iron-scintillator hadron prototype calorimeter with longitudinal tile configuration is presented. These results are based on electron and pion beams data of E = 20, 50, 100, 150, 300 GeV at $

G. Modanese

It was recently suggested that the gravitational action could contain a scale-dependent cosmological term, depending on the length or momentum scale characteristic of the processes under consideration. In this work we explore a simple possible consequence of this assumption. We compute the field generated in empty space by a static spherical source (the Schw

S. M. Wagh, S. D. Maharaj

We investigate the formation of a locally naked singularity in the collapse of radiation shells in an expanding Vaidya-deSitter background. This is achieved by considering the behaviour of non-spacelike and radial geodesics originating at the singularity. A specific condition is determined for the existence of radially outgoing, null geodesics originating at

Thomas Kistler, Michael Franz

We present an open architecture for just-in-time code generation and dynamic code optimization that is flexible, customizable, and extensible. While previous research has primarily investigated functional aspects of such a system, architectural aspects have so far remained unexplored. In this paper, we argue that these properties are important to generate op

E. Orignac, T. Giamarchi, P. Le Doussal

A new thermodynamic phase resulting from the competition between a commensurate potential and disorder in interacting fermionic or bosonic systems is predicted. It requires interactions of finite extent. This phase, intermediate between the Mott insulator and the Anderson insulator, is both incompressible and has no gap in the conductivity. The corresponding

Martin R. Zirnbauer

Kamenev and Mezard, and Yurkevich and Lerner, have recently shown how to reproduce the large-frequency asymptotics of the energy level correlations for disordered electron systems, by doing perturbation theory around the saddles of the compact nonlinear sigma model derived from fermionic replicas. We present a critical review of their procedure and argue tha

Kieran Mullen

Dislocations and disclinations in a lattice of Josephson junctions will affect the dynamics of vortex excitations within the array. These defects effectively distort the space in which the excitations move and interact. The interaction energy between such defects and excitations are determined and vortex trajectories in twisted lattices are calculated. Final

Francois Drolet, Jorge Vinals

A mesoscopic model of a diblock copolymer is used to study the stability of a lamellar structure under a uniform shear flow. We first obtain the nonlinear lamellar solutions under both steady and oscillatory shear flows. Regions of existence of these solutions are determined as a function of the parameters of the model and of the flow. Finally, we address th

R. J. Keizer, A. de Visser, M. J. Graf, A. A. Menovsky

The effect of Pd doping on the superconducting phase diagram of the unconventional superconductor UPt3 has been measured by (magneto)resistance, specific heat, thermal expansion and magnetostriction. Experiments on single- and polycrystalline U(Pt1-xPdx)3 for x<= 0.006 show that the superconducting transition temperatures of the A phase, Tc+, and of the B ph

Valeria Ferrari, Guillermo Chiappe, Enrique V. Anda, Maria A. Davidovich

The persistent current through a quantum dot inserted in a mesoscopic ring of length L is studied. A cluster representing the dot and its vicinity is exactly diagonalized and embedded into the rest of the ring. The Kondo resonance provides a new channel for the current to flow. It is shown that due to scaling properties, the persistent current at the Kondo r

Jon Magne Leinaas

In two space dimensions the possibilities of fractional spin as well as fractional statistics exist. I examine the relation between fractional spin and statistics for Laughlin quasi-particles in a two-dimensional electron system with spherical geometry. The relevance of this for quasi-particles in a planar system is discussed.

R. J. Keizer, A. de Visser, A. A. Menovsky, J. J. M. Franse

Neutron-diffraction experiments have been carried out on U(Pt1-xPdx)3 single crystals (x<= 0.05). The small-moment antiferromagnetic order (SMAF) reported for pure UPt3 is robust upon doping and persists till at least x= 0.005. The ordered moment grows from 0.018(2) mB/U-atom for pure UPt3 to 0.048(8) mB/U-atom for x= 0.005. The Neel temperature, TN, is appr

A. Siber, B. Gumhalter

Following the recently accumulated information on the vibrational properties of the Cu(001) surface acquired through single- and multiphonon He atom scattering experiments and the concomitant theoretical investigations, we have reexamined the properties of the Debye-Waller factor (DWF) characteristic of the He \to Cu(001) collisions using the recently develo

Christofer Cronstrom, Milan Noga

Within the simplest model of metals, namely a gas of electrons with Coulomb interactions, in the presence of a uniform background of positive charge to enforce electric neutrality of the system, we have derived a mechanism, by which the Coulomb interaction between the electrons generates a new kind of magnetism. The ground state of the metal is represented b

Ronald Blaak, Daan Frenkel, Bela M. Mulder

We investigate the possibility that freely rotating cylinders with an aspect ratio $L/D=0.9$ exhibit a cubatic phase similar to the one found for a system of cut-spheres. We present theoretical arguments why a cubatic phase might occur in this particular system. Monte Carlo simulations do not confirm the existence of a cubatic phase for cylinders. However, t

A. Barrat

In a recent letter (cond-mat/9903108), Barthelemy and Nunes Amaral discuss the crossover phenomenon between regular and ``small-world&#39;&#39; networks, as a function of the network size $n$ and of the disorder $p$. They claim that the average distance $\ell$ between vertices of the network scales with $n / n^*$, with $n^*(p \ll 1) sim p^{-τ}$ and $τ\approx

J. H. Jung, J. S. Ahn, T. W. Noh, Jinhyoung Lee

Temperature and polarization dependent electronic structure of La1/2Sr3/2MnO4 were investigated by optical conductivity analyses. With decreasing temperature, for E//ab, a broad mid-infrared (MIR) peak of La1/2Sr3/2MnO4 becomes narrower and moves to the higher frequency, while that of Nd1/2Sr3/2MnO4 nearly temperature independent. We showed that the MIR peak

Alexei Vazquez, Oscar Sotolongo-Costa

The dynamics of an elastic interface profile h(x,t) under a driving force increasing at rate c, a restored force -epsilon h, and disorder is investigated. Using perturbation theory and functional renormalization group the phase diagram and the scaling exponents, up to the first order in 4-d, are obtained. The model is found to be critical in the double limit

L. Armus, B. T. Soifer, G. Neugebauer

With a infrared luminosity of nearly 10^13 Lsuns, IRAS 09104+4109 is the most luminous galaxy with z<0.5 in the IRAS All Sky Survey. A radio-loud Seyfert 2 type optical spectrum, a cD host galaxy in a rich cluster, and a massive cooling flow make IRAS 09104+4109 unique among ultraluminous infrared galaxies. Cannibalized cluster members and the cooling interc

J. F. C. Santos, A. E. Piatti, J. J. Claria, E. Bica

A comparative analysis of Washington color-magnitude diagrams (CMDs) for 14 star clusters and respective surrounding fields in the Large Magellanic Cloud (LMC) outer disk is presented. Each CCD frame including field and respective cluster covers an area of 185 arcmin^2. The stellar population sampled is of intermediate age and metallicity. CMD radial analysi

V. Tatischeff, R. Ramaty, A. Valinia

A distinct low energy cosmic-ray component has been proposed to explain the essentially constant Be/Fe ratio at low metallicities. Atomic collisions of such low energy ions produce characteristic nonthermal X-ray emission. In this paper, we study the possible contribution of such X-rays to the Galactic ridge emission. We show that they would account for < 10

Milan M. Cirkovic, J. Bland-Hawthorn, Srdjan Samurovic

Recent highly sensitive detections of line emission from extended gas in the local universe demonstrate the feasibility of detecting H$α$ emitting galactic halos out to $z\sim1$. We determine the form of the surface brightness vs. redshift dependence which takes into account UV background evolution. Successful detections will have a major impact on a wide ra

Markus Kissler-Patig, Keith M. Ashman, Stephen E. Zepf, Kenneth C. Freeman

We present a study of the globular cluster systems of two edge-on spiral galaxies, NGC4565 and NGC5907, from WFPC2 images in the F450W and F814W filters. The globular cluster systems of both galaxies appear to be similar to the Galactic globular cluster system. In particular, we derive total numbers of globular clusters of N_{GC}(4565)= 204+/-38 {+87}{-53} a

Ennio Poretti

The importance of Cepheids is well known in many fields of astronomy. Section 2 introduces the Fourier decomposition, a tool to describe quantitatively the light curves of pulsating stars. Sect. 3 shows how an observational result was progressively built on the basis of old and new data; the latter were collected on selected targets just to clarify some cont

L. Chiappetti, L. Maraschi, F. Tavecchio, A. Celotti

We present the results of BeppoSAX observations of PKS 2155-304 during an intense gamma-ray flare. The source was in a high X-ray state. A temporal analysis of the data reveals a tendency of the amplitude of variations to increase with energy, and the presence of a soft lag with a timescale of the order 10^3 s. A curved continuum spectrum, with no evidence o

Roger M. Hutchings, Peter A. Thomas

We model a one-dimensional shock-tube using smoothed particle hydrodynamics and investigate the consequences of having finite shock-width in numerical simulations. We investigate the cooling of gas during passage through the shock for different cooling regimes. For a shock temperature of 10^5K, the maximum temperature of the gas is much reduced and the cooli

Dominik J. Schwarz, Christoph Schmid, Peter Widerin

The cosmological QCD transition affects primordial density perturbations. If the QCD transition is first order, the sound speed vanishes during the transition and density perturbations fall freely. For scales below the Hubble radius at the transition the primordial Harrison-Zel&#39;dovich spectrum of density fluctuations develops large peaks and dips. These

A. P. Lobanov, J. A. Zensus

The long-term evolution of the synchrotron emission from the parsec-scale jet in the quasar 3C345 is analysed, on the basis of multi-frequency monitoring with very long baseline interferometry (VLBI) and covering the period 1979-1994. We combine the model fits from 44 VLBI observations of 3C345 made at 8 different frequencies between 2.3 and 100GHz. We calcu

R. X. Chang, J. L. Hou, C. G. Shu, C. Q. Fu

In the present paper, we introduce a two-component model of the Galactic disk to investigate its chemical evolution. The formation of the thick and thin disks occur in two main accretion episodes with both infall rates to be Gaussian. Both the pre-thin and post-thin scenarios for the formation of the Galactic disk are considered. The best-fitting is obtained

H. Hirashita

We examine the dust-to-gas ratio as a function of metallicity for dwarf galaxies [dwarf irregular galaxies (dIrrs) and blue compact dwarf galaxies (BCDGs)]. Using a one-zone model and adopting the instantaneous recycling approximation, we prepare a set of basic equations which describes processes of dust formation and destruction in a galaxy. Four terms are

M. Longhetti, A. Bressan, C. Chiosi, R. Rampazzo

We analyze the star formation properties of a sample of 21 shell galaxies and 30 early-type galaxies members of interacting pairs, located in low density environments (Longhetti et al 1998a, 1998b). The study is based on new models developed to interpret the information coming from `blue&#39; H$δ$/FeI, H+K(CaII) and \D4000 line-strength indices proposed by R

I. H. Stairs, D. J. Nice, S. E. Thorsett, J. H. Taylor

We present a new timing solution for PSR B1534+12, based on coherently-dedispersed observations at Jodrell Bank and, recently, Arecibo. The new data have resulted in improved measurements of the post-Keplerian timing parameters, including the orbital period derivative. At present, the poorly-known distance to the pulsar limits the precision of the measuremen

S. M. Barr, Shaaban Khalil

We examine the cancellation mechanism between the different contributions to the electric dipole moment of the neutron in a model with dilaton-dominated SUSY breaking. We find these accidental cancellations occur at few points in parameter space. For a wide region of this space we must constrain the phase of $μ$ to be of order $10^{-1}$ and have the phases o

M. V. Chizhov, S. T. Petcov

The extrema of the probabilities of the transitions $ν_μ (ν_e) \to ν_e (ν_{μ;τ})$, $ν_{2} \to ν_e$, etc. of neutrinos passing through a medium consisting of i) two layers of different constant densities or ii) three layers of constant density, of which the first and the third are identical but differ in density from the second (e.g., mantle-core-mantle in th

H. Ness, A. J. Fisher

We calculate non-perturbatively the inelastic effects on the conductance through a conjugated molecular wire-metal heterojunction, including realistic electron-phonon coupling. We show that at sub-band-gap energies the current is dominated by quantum coherent transport of virtual polarons through the molecule. In this regime, the tunneling current is strongl

Galit Eyal

We investigate supersymmetric models in which an anomalous $U(1)_{X}$ symmetry explains the Yukawa hierarchy, and the related $D_{X}$-term plays a role in supersymmetry breaking. We use a bottom-up approach to model building. Phenomenological viability leads to a scenario with degenerate squark and slepton spectra and with heavy gauginos. Features of a Kähle

Peter Bouwknegt, Leung Chim, David Ridout

In this paper we further elaborate on the notion of fractional exclusion statistics, as introduced by Haldane, in two-dimensional conformal field theory, and its connection to the Universal Chiral Partition Function as defined by McCoy and collaborators. We will argue that in general, besides the pseudo-particles introduced recently by Guruswamy and Schouten

Alejandro Ayala, Gordon Baym, James L. Popp

The Hanbury Brown--Twiss (HBT) effect in two-particle correlations is a fundamental wave phenomenon that occurs at the sensitive elements of detectors; it is one of the few processes in elementary particle detection that depends on the wave mechanics of the produced particles. We analyze here, within a quantum mechanical framework for computing correlations

Xian-Jin Li

In 1952 Peter Roquette gave an arithmetic proof of the Riemann hypothesis for algebraic function fields of a finite constants field, which was proved by André Weil in 1940. The construction of Weil&#39;s scalar product is essential in Roquette&#39;s proof. In this paper a scalar product for algebraic function fields over a number field is constructed which i

Boris Tsirelson

Independent random signs can govern various discrete models that converge to non-isomorphic continuous limits. Convergence of Fourier-Walsh spectra is established under appropriate conditions.

Zhang-Ju Liu, Ping Xu

The purpose of this paper is to establish a connection between various subjects such as dynamical r-matrices, Lie bialgebroids, and Lagrangian subalgebras. Our method relies on the theory of Dirac structures developed in dg-ga/9508013 and dg-ga/9611001. In particular, we give a new method of classifying dynamical r-matrices of simple Lie algebras $\frak g$,

Malgorzata Bakalarska, Boguslaw Broda

Description of two three-dimensional topological quantum field theories of Witten type as twisted supersymmetric theories is presented. Low-energy effective action and a corresponding topological invariant of three-dimensional manifolds are considered.

B. Melic, B. Nizic, K. Passek

We comment on the results of a complete leading-twist next-to-leading order QCD analysis of the spacelike pion electromagnetic form factor at large-momentum transfer Q. For the asymptotic distribution amplitude, we have examined the sensitivity of the predictions to the choice of the renormalization scale. The results show that reliable perturbative predicti

Schuyler Cullen, Maxim Perelstein

Recently there has been a lot of interest in models in which gravity becomes strong at the TeV scale. The observed weakness of gravitational interactions is then explained by the existence of extra compact dimensions of space, which are accessible to gravity but not to Standard Model particles. In this letter we consider graviton emission into these extra di

Tai-fu Feng

We perform the complete computation of the contributions to $b\to s+γ, b\to s e^{+}e^{-}, b\to s\sum ν_{i} \barν_{i}$ in supersymmetric model with bilinear R-parity violation. We compare our calculations with the evaluations in SM and the experimental results. We find that the supersymmetric contributions can be quite large in those processes. From the analy