January 2000 arXiv papers — page 16

V. Anguelov, H. Vankov

We present the results concerning the main shower characteristics in a strong magnetic field obtained through shower simulation. The processes of magnetic bremsstrahlung and pair production were taken into account for values of the parameter $χ\gg 1$. We compare our simulation results with a recently developed cascade theory in a strong magnetic field.

Takuji Tsujimoto, Toshikazu Shigeyama, Yuzuru Yoshii

We suggest that if the astrophysical site for r-process nucleosynthesis in the early Galaxy is confined to a narrow mass range of Type II supernova (SN II) progenitors, with a lower mass limit of Mms = 20 Msun, a unique feature in the observed distribution of [Ba/Mg] vs.[Mg/H] for extremely metal-poor stars can be adequately reproduced. We associate this fea

Kunihito Ioka, Keisuke Taniguchi

We investigate the effects of the magnetic dipole-dipole coupling and the electromagnetic radiation on the frequency evolution of gravitational waves from inspiralling binary neutron stars with magnetic dipole moments. This study is motivated by the discovery of the superstrongly magnetized neutron stars, i.e., magnetar. We derive the contributions of the ma

R. G. H. Robertson

Current evidence for neutrino oscillation is reviewed, some areas for closer investigation are suggested, and a plausible future experimental program is summarized.

Mannque Rho, Edward Shuryak, Andreas Wirzba, Ismail Zahed

QCD superconductors in the color-flavor-locked (CFL) phase support excitations (generalized mesons) that can be described as pairs of particles or holes (rather than particle-hole) around a gapped Fermi surface. In weak coupling and to leading logarithm accuracy the scalar and pseudoscalar excitations are massless and the vector and axial-vector excitations

M. J. Konstantinovic, Z. V. Popovic, M. Isobe, Y. Ueda

We present the Raman-scattering spectra of CaV2O5 and MgV2O5. The magnetic contribution in the Raman spectra of CaV2O5 is found in the form of a strong asymmetric line, centered at 2Delta, with a tail on the high-energy side. Our analysis of its spectral shape shows that the magnetic ordering in CaV2O5 can be described using a S=1/2 two-leg ladder Heisenberg

A. Sagnotti

I review the salient features of three classes of open-string models with broken supersymmetry. These suffice to exhibit, in relatively simple settings, the two phenomena of ``brane supersymmetry'' and ``brane supersymmetry breaking''. In the first class of models, to lowest order supersymmetry is broken both in the closed and in the open sec

C. Giunti, M. C. Gonzalez-Garcia, C. Peña-Garay

We present an analysis of the neutrino oscillation solutions of the solar neutrino problem in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones. We perform a fit to the full data set corresponding to the 825-day Super-Kamiokande data sample as well as to Chlorine, GALLEX and SAGE and Kamiokande experiments. In

Shigeyuki Komura, David Andelman

Adhesion between membranes is studied using a phenomenological model, where the inter-membrane distance is coupled to the concentration of sticker molecules on the membranes. The model applies to both for adhesion of two flexible membranes and to adhesion of one flexible membrane onto a second membrane supported on a solid substrate. We mainly consider the c

P. L. Garrido, Miguel A. Muñoz, F. de los Santos

Motivated by some recent criticisms to our alternative Langevin equation for driven lattice gases (DLG) under an infinitely large driving field, we revisit the derivation of such an equation, and test its validity. As a result, an additional term, coming from a careful consideration of entropic contributions, is added to the equation. This term heals all the

M. Crescimanno, C. G. Koay, R. Peterson, R. Walsworth

We use a modified Thomas-Fermi approximation to estimate analytically the critical velocity for the formation of vortices in harmonically trapped BEC. We compare this analytical estimate to numerical calculations and to recent experiments on trapped alkali condensates.

L. Benet, T. H. Seligman

In rotating scattering systems, the generic saddle-center scenario leads to stable islands in phase space. Non-interacting particles whose initial conditions are defined in such islands will be trapped and form rotating rings. This result is generic and also holds for systems quite different from planetary rings.

Cristina Manuel, Michel H. G. Tytgat

We construct the U_L(3) x U_R(3) effective lagrangian which encodes the dynamics of the low energy pseudoscalar excitations in the Color-Flavor-Locking superconducting phase of QCD at finite quark density. We include the effects of instanton-induced interactions and study the mass pattern of the pseudoscalar mesons. A tentative comparison with the analytical

P. F. L. Maxted, T. R. Marsh, C. K. J. Moran, Z. Han

WD1704+481 is a visual binary in which both components are white dwarfs. We present spectra of the H-alpha line of both stars which show that one component (WD1704+481.2 = Sanduleak B = GR 577) is a close binary with two white dwarf components. Thus, WD1704+481 is the first known triple degenerate star. From radial velocity measurements of the close binary w

P. Astone, G. Pizzella

A procedure with a Bayesan approach for calculating upper limits to gravitational wave bursts from coincidence experiments with multiple detectors is described.

P. Valageas, J. Silk, R. Schaeffer

We study the distribution of baryonic and luminous matter within the framework of a hierarchical scenario. Using an analytical model for structure formation which has already been checked against observations for galaxies, Lyman-$α$ clouds, clusters and reionization processes, we present its predictions for the bias of these objects. We describe its dependen

A. Takami, T. Hashimoto, M. Horibe, A. Hayashi

We investigate, analytically and numerically, the fermion determinant of a new action on a (1+1)-dimensional Euclidean lattice. In this formulation the discrete chiral symmetry is preserved and the number of fermion components is a half of that of Kogut-Susskind. In particular, we show that our fermion determinant is real and positive for U(1) gauge group un

Omar Mustafa, Maen Odeh

A new pseudoperturbative (artificial in nature) methodical proposal [15] is used to solve for Schrodinger equation with a class of phenomenologically useful and methodically challenging anharmonice oscillator potentials V(q)=α_o q^2 + αq^4. The effect of the [4,5] Pade' approximant on the leading eigenenergy term is studied. Comparison with results from

Kazuya Koyama, Jiro Soda

Birth of the brane world is studied using the Hamiltonian approach. It is shown that an inflating brane world can be created from nothing. The wave function of the universe obtained from the Wheeler de-Witt equation and the time-dependent Schr$\ddot{o}$dinger equation for quantized scalar fields on the brane are the same as in the conventional 4-dimensional

B. Grzadkowski, J. F. Gunion, J. Kalinowski

Already in the simplest two-Higgs-doublet model with CP violation in the Higgs sector, the $3\times3$ mixing matrix for the neutral Higgs bosons can substantially modify their couplings, thereby endangering the ``classical'' Higgs search strategies. However, there are sum rules relating Yukawa and Higgs-Z couplings which ensure that the ZZ, $b\anti b

Gordon L. Kane, Malcolm J. Perry, Anna N. Zytkow

We argue that if string theory as an approach to the fundamental laws of physics is correct, then there is almost no room for anthropic arguments in cosmology. The quark and lepton masses and interaction strengths are determined.

Yonatan Zunger

Particle and string actions on coset spaces typically lack a quadratic kinetic term, making their quantization difficult. We define a notion of twistors on these spaces, which are hypersurfaces in a vector space that transform linearly under the isometry group of the coset. By associating the points of the coset space with these hypersurfaces, and the intern

Philip Pearle, James Ring, Juan I. Collar, Frank T. Avignone

A brief review is given of the Continuous Spontaneous Localization (CSL) model in which a classical field interacts with quantized particles to cause dynamical wavefunction collapse. One of the model's predictions is that particles "spontaneously" gain energy at a slow rate. When applied to the excitation of a nucleon in a Ge nucleus, it is shown

V. B. Belyaev, M. B. Miller, A. V. Sermyagin

At the Institute in Physical-Technical Problems experiments on sonoluminescence was started by our group at the beginning of 1998. The study was focused at properties of the SBSL, and the aim was to find more optimum conditions for a search for some recently predicted rare effects in SBSL- process.

J. G. Muga, M. Buttiker

The time dependence of quantum evanescent waves generated by a point source with an infinite or a limited frequency band is analyzed. The evanescent wave is characterized by a forerunner (transient) related to the precise way the source is switched on. It is followed by an asymptotic, monochromatic wave which at long times reveals the oscillation frequency o

Yu-Xi Liu, Chang-pu Sun

We study the hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells. The corresponding polariton states are given. The analytical solution and the numerical result of the stationary spectrum for the cavity field are finished

Yu-xi Liu, Chang-pu Sun

The interaction between the radiation field in a microcavity with a mirror undergoing damping oscillation is investigated. Under the heavily damping cases, the mirror variables are adiabatically eliminated. The the stationary conditions of the system are discussed. The small fluctuation approximation around steady values is applied to analysis the antibunchi

Gina Hamilton

Until this century, the number of working female scientists has been indeterminate. Prevailing wisdom indicates that women, historically, have not excelled in the mathematics and sciences, for various reasons. These range from societal pressures to marry and bear children, to a lack of systematic scientific education for females, to the lack of opportunity i

S. Kondratyuk, O. Scholten

We present a model for dressing the nucleon propagator and vertices. In the model the use of a K-matrix approach (unitarity) and dispersion relations (analyticity) are combined. The principal application of the model lies in pion-nucleon scattering where we discuss effects of the dressing on the phase shifts.

R. D. Pinto, P. Varona, A. R. Volkovskii, A. Szucs

We report on experimental studies of synchronization phenomena in a pair of analog electronic neurons (ENs). The ENs were designed to reproduce the observed membrane voltage oscillations of isolated biological neurons from the stomatogastric ganglion of the California spiny lobster Panulirus interruptus. The ENs are simple analog circuits which integrate fou

J. Timmer

We discuss the problem of parameter estimation in nonlinear stochastic differential equations based on sampled time series. A central message from the theory of integrating stochastic differential equations is that there exists in general two time scales, i.e. that of integrating these equations and that of sampling. We argue that therefore maximum likelihoo

T. Uezu

In the symmetric and the asymmetric trapezoid maps, as a slope of the trapezoid is increased, the period doubling cascade occurs and the symbolic sequence of periodic points is the Metropolis-Stein-Stein sequence and the convergence of the onset point of the period 2^m solution to the accumulation point is exponentially fast. We reported these results previo

Boris Tsirelson

The set of zeros of a Brownian motion gives rise to a product system in the sense of William Arveson (that is, a continuous tensor product system of Hilbert spaces). Replacing the Brownian motion with a Bessel process we get a continuum of non-isomorphic product systems.

Alessandro Arsie

Generalizing the construction of the Maslov class for a Lagrangian embedding in a symplectic vector space, we prove that it is possible to give a consistent definition of this class for any Lagrangian submanifold of a Calabi-Yau manifold. Moreover, we prove that this class can be represented by the contraction of the Kaehler form associated to the Calabi-Yau

Guangfeng Jiang

The main object of this note is to study the conormal module $M$ and the computation of the second symbolic power $\bar I^{(2)}$ of an ideal $\bar I$ in the residue ring $R/H$ of a polynomial ring $R$ over a field of characteristic zero. The torsion part $T(M)$ of $M$ and the torsion free module $M/T(M)$ are expressed by the primitive ideal of $I$ relative t

Roman R. Zapatrin

With any locally finite partially ordered set $K$ its incidence algebra $Ω(K)$ is associated. We shall consider algebras over fields with characteristic zero. In this case there is a correspondence $K \leftrightarrow Ω(K)$ such that the poset $K$ can be reconstructed from its incidence algebra up to an isomorphism -- due to Stanley theorem. In the meantime,

T. Oaku, N. Takayama, H. Tsai

The aim of this paper is to give two new algorithms, which are elimination free, to find polynomial and rational solutions for a given holonomic system associated to a set of linear differential operators in the Weyl algebra D = k<x_1, ..., x_n, dx_1, ..., dx_n> where k is a subfield of the complex numbers.

Georgios Metikas

We discuss the use of derivative expansion techniques for the construction of thermal effective potentials. We present a theory for which the thermal bubble is analytic at the origin of the momentum-frequency space, although the internal propagators in the loop have the same mass. This means that, for this theory, the thermal effective potential is uniquely

Semyon Pol&#39;shin

Two different systems of the generalized coherent states for the de Sitter group are constructed. These systems have the physical sense of particles and antiparticles over de Sitter space and obeys the Klein-Gordon equation. Using these systems the de Sitter-invariant propagators for massive spin~0 and~1/2 fields over de Sitter space are constructed.

Agapitos Hatzinikitas

The goal of this note is to provide a recursive algorithm that allows one to calculate the expansion of the metric tensor up to the desired order in Riemann normal coordinates. We test our expressions up to fourth order and predict results up to sixth order. For an arbitrary number of symmetric partial derivatives acting on the components of the metric tenso

M. Billo&#39;, M. Caselle, A. D&#39;adda, P. Provero

We consider two-dimensional Yang-Mills theories on arbitrary Riemann surfaces. We introduce a generalized Yang-Mills action, which coincides with the ordinary one on flat surfaces but differs from it in its coupling to two-dimensional gravity. The quantization of this theory in the unitary gauge can be consistently performed taking into account all the topol

Matthew D. E. Szyndel

We investigate the sigma and baby Skyrme models with an RP^2 target space. We compare these models to models with an S^2 target space. We investigate the interactions between solitons and defects in the RP^2 sigma model.

R. Caseiro, J. -P. Francoise, R. Sasaki

Calogero-Moser systems can be generalized for any root system (including the non-crystallographic cases). The algebraic linearization of the generalized Calogero-Moser systems and of their quadratic (resp. quartic) perturbations are discussed.

Andre Wehner, James T. Wheeler

We extend 2n-dim biconformal gauge theory by including Lorentz-scalar matter fields of arbitrary conformal weight. We show that for a massless scalar field of conformal weight zero in a torsion-free biconformal geometry, the solution is determined by the Einstein equation on an n-dim submanifold, with the stress-energy tensor of the scalar field as source. T

Gordon P. Ramsey

There have been many versions of spin-dependent parton distributions in the literature. Although most agree with present data within uncertainties, they are based upon different physical assumptions. Some physical models are discussed and the corresponding predictions for double spin asymmetries are shown. A summary of the most feasible measurements in the a

C. Balazs, C. -P. Yuan

We present results of QCD corrections to Higgs boson production at the CERN Large Hadron Collider. Potentially large logarithmic contributions from multiple soft-gluon emission are summed up to all order in the strong coupling. Various kinematical distributions, including the Higgs transverse momentum, are predicted with O(alpha_s^3) precision. Comparison is

B. Borasoy

We include in a systematic way the eta&#39; in baryon chiral perturbation theory. The most general relativistic effective Lagrangian describing the interaction of the lowest lying baryon octet with the Goldstone boson octet and the eta&#39; is presented up to linear order in the derivative expansion and its heavy baryon limit is obtained. As explicit example

M. Vanderhaeghen, J. M. Friedrich, D. Lhuillier, D. Marchand

The QED radiative corrections to virtual Compton scattering (reaction $e p \to e p γ$) are calculated to first order in $α_{em} \equiv e^2 / 4 π$. A detailed study is presented for the one-loop virtual corrections and for the first order soft-photon emission contributions. Furthermore, a full numerical calculation is given for the radiative tail, correspondi

Isard Dunietz

Because the Bd -> J/psi Ks asymmetry determines only sin(2 beta), a discrete ambiguity in the true value of beta remains. This note reviews how the ambiguity can be removed. Extractions of the CKM angle alpha are discussed next. Some of the methods require very large data samples and will not be feasible in the near future. In the near future, semi-inclusive

Wilfried Buchmuller, Stefan Fredenhagen

Basic ingredients of the theory of baryogenesis are reviewed with emphasis on out-of-equilibrium decays of heavy particles. The present use of kinetic theory is explained and some attempts to go beyond the classical Boltzmann equations are discussed.

A. B. Kaidalov, A. P. Krutenkova

Different aspects of the Gribov--Glauber approach for calculation of inclusive pion double charge exchange (DCX) on nuclei are investigated. Recently we have shown that inelastic rescatterings (IR) with two (and more) pions in the intermediate states give an important contribution to the process of DCX at energies above $\sim0.6 GeV$. In this paper we use th

A. L. Kataev, G. Parente, A. V. Sidorov

The summary of the results of our next-to-next-to-leading fits of Tevatron experimental data for $xF_3$ structure function of the $νN$ deep-inelastic scattering is given. The special attention is paid to the extraction of twist-4 contributions and demonstration of the interplay between these effects and higher-order perturbative QCD corrections. The factoriz

Bo-Qiang Ma

It is shown that the proton &#34;spin crisis&#39;&#39; or &#34;spin puzzle&#34; can be understood by the relativistic effect of quark transversal motions due to the Melosh-Wigner rotation. The quark helicity $Δq$ measured in polarized deep inelastic scattering is actually the quark spin in the infinite momentum frame or in the light-cone formalism, and it is

Konstantin Goulianos

A phenomenological model of hard diffraction is presented, in which the structure of the Pomeron is derived from the structure of the parent hadron. Predictions for diffractive deep inelastic scattering are compared with data.

F. Berruto, G. Grignani, P. Sodano

We analyse - within the hamiltonian formalism with staggered fermions - the patterns of chiral symmetry breaking for the strongly coupled Schwinger and $U({\cal N}_c)$-color `t Hooft models with one and two flavor of fermions. Using the correspondence between these strongly coupled gauge models and antiferromagnetic spin chains, we provide a rather intuitive

H. Arisue

We calculate the large-q expansion of the second moment correlation length at the first order phase transition point of the q-state Potts model in two dimensions both in the ordered and disordered phases to order 21 in $1/\sqrt{q}$. They coincide with each other to the third term of the series but differ a little in higher orders. Numerically the ratio of th

Valery Telnov

The idea of plasma suppression of beam-beam effects at muon colliders is discussed. It is shown that one should take into account collisions in the plasma that were ignored before. Rough estimates show that this effect leads to a fast ``recovery&#39;&#39; of the beam magnetic field. For beam parameters characteristic for muon colliders the suppression of the

Valery Telnov

It is shown that at a 100 TeV muon collider the synchrotron radiation in the ring will determine the minimum horizontal emittance.

Valery Telnov

It is shown that at muon colliders with the energy in the region of 100 TeV the process of coherent pair creation by the muon in the field of the opposing beam becomes important and imposes some limitations on collider parameters.

Valery Telnov

It is well known that at linear e^+e^-(e^-e^-) colliders using laser backscattering one can obtain colliding gamma-gamma, gamma-electron beams with energy and luminosity comparable to those in e^+e^- collisions. In this paper, it is explained why this can not be done at high energy muon colliders. Due to several physics reasons the gamma-gamma luminosity is

Valery Telnov

Using the laser backscattering method at future linear colliders one can obtain gamma-gamma and gamma-electron colliding beams (photon colliders) with energy and luminosity comparable to that in e^+e^- collisions. This option has been included in the pre-conceptual designs of linear colliders and in work on a Technical Design Report which is in progress. The

Valery Telnov

A method of electron beam cooling is considered which can be used for linear colliders. The electron beam is cooled during collision with focused powerful laser pulse. The ultimate transverse emittances are much below those achievable by other methods. This method is especially useful for high energy gamma-gamma colliders. In this paper we review and analyse

Y. A. Kulchitsky, V. B. Vinogradov

The extension of the longitudinal hadronic shower profile parameterization which takes into account non-compensations of calorimeters and the algorithm of the longitudinal hadronic shower profile curve making for a combined calorimeter are suggested. The proposed algorithms can be used for data analysis from modern combined calorimeters like in the ATLAS det

Dinesh Loomba, Valerie Halyo, Eric R. Lee, Irwin T. Lee

We present a new experimental method for searching for free fractional charge in bulk matter; this new method derives from the traditional Millikan liquid drop method, but allows the use of much larger drops, 20 to 100 mm in diameter, compared to the traditional method that uses drops less than 15 mm in diameter. These larger drops provide the substantial ad

Semyon Pol&#39;shin

The group theoretical approach to the relativistic wave equations in the de Sitter and Anti-de Sitter spaces for spin~0 and 1/2 massive particles is considered. The invariant wave equations which determines the appropriate irreducible representations are constructed. The explicit solutions of these equations possessing a simplicity and physical transparency

Kazuya Koyama, Kayoko Maeda, Jiro Soda

It appears difficult to construct a simple model for an open universe based on the one bubble inflationary scenario. The reason is that one needs a large mass to avoid the tunneling via the Hawking Moss solution and a small mass for successful slow-rolling. However, Rubakov and Sibiryakov suggest that the Hawking Moss solution is not a solution for the false

Nikolay Mateev, Vijay Menon, Keshav Pingali

Restructuring compilers use dependence analysis to prove that the meaning of a program is not changed by a transformation. A well-known limitation of dependence analysis is that it examines only the memory locations read and written by a statement, and does not assume any particular interpretation for the operations in that statement. Exploiting the semantic

B. Jancovici

In a two-dimensional two-component plasma, the second moment of the density correlation function has the simple value {12 pi [1-(gamma/4)]^2}^{-1}, where gamma is the dimensionless coupling constant. This result is derived by using analogies with critical systems.

Martin Howard, R. K. P. Zia

We study the population profile in a simple discrete time model of population dynamics. Our model, which is closely related to certain ``bit-string&#39;&#39; models of evolution, incorporates competition for resources via a population dependent death probability, as well as a variable reproduction probability for each individual as a function of age. We firs

Z. V. Popovic, R. Gajic, M. J. Konstantinovic, R. Provoost

The phonon dynamics of LiV2O5 single crystals is studied using infrared and Raman spectroscopy techniques. The infrared-active phonon frequencies and dielectric constants are obtained by oscillator fitting procedure of the reflectivity data measured at room temperature. The Raman scattering spectra are measured at room temperature and at T=10 K in all nonequ

Xin-Zhong Yan, Hongwei Zhao, Chia-Ren Hu

On the basis of the Keldysh method of non-equilibrium systems, we develop a theory of electron tunneling in normal-metal/superconductor junctions. By using the tunneling Hamiltonian model (being appropriate for the tight-binding systems), the tunneling current can be exactly obtained in terms of the equilibrium Green functions of the normal metal and the sup

R. Cote, H. A. Fertig

The collective modes of striped phases in a quantum Hall system are computed using the time-dependent Hartree-Fock approximation. Uniform stripe phases are shown to be unstable to the formation of modulations along the stripes, so that within the Hartree-Fock approximation the groundstate is a stripe crystal. Such crystalline states are generically gapped at

N. Bailey, J. Sethna, C. Myers

In seeking to understand at a microscopic level the response of dislocations to stress we have undertaken to study as completely as possible the simplest case: a single dislocation in a two dimensional crystal. The intention is that results from this study will be used as input parameters in larger length scale simulations involving many defects. We present

J. David Kokales, Patrick Fournier, Lucia V. Mercaldo, Vladimir V. Talanov

The pairing state symmetry of the electron-doped cuprate superconductors is thought to be s-wave in nature, in contrast with their hole-doped counterparts which exhibit a d-wave symmetry. We re-examine this issue based on recent improvements in our electron-doped materials and our measurement techniques. We report microwave cavity perturbation measurements o

N. Markovic, C. Christiansen, D. E. Grupp, A. M. Mack

The temperature dependence of the resistance R(T) of ultrathin quench-condensed films of Ag, Bi, Pb and Pd has been investigated. In the most resistive films, R(T)=Roexp(To/T)^x, where x=0.75. Surprisingly, the exponent x was found to be constant for a wide range of Ro and To in all four materials, possibly implying a consistent underlying conduction mechani

Bernd Rinn, Philipp Maass, Jean-Philippe Bouchaud

We investigate aging in glassy systems based on a simple model, where a point in configuration space performs thermally activated jumps between the minima of a random energy landscape. The model allows us to show explicitly a subaging behavior and multiple scaling regimes for the correlation function. Both the exponents characterizing the scaling of the diff

J. B. Staunton, J. Poulter, B. Ginatempo, E. Bruno

A scheme for making ab-initio calculations of the dynamic paramagnetic spin susceptibilities of solids at finite temperatures is described. It is based on Time-Dependent Density Functional Theory and employs an electronic multiple scattering formalism. Incommensurate and commensurate anti-ferromagnetic spin fluctuations in paramagnetic Cr and compositionally

Iskander G. Batirev, Ali Alavi, Michael W. Finnis

We derive a formula, useful for first-principles calculations, which relates the free energy of an oxide/metal interface to the free energies of surfaces and the work of separation of the interface. We distinguish the latter {\it mechanical} quantity from the {\it thermodynamic} work of adhesion, and we describe explicitly how both may be calculated. Our for

H. Chamati, D. M. Danchev, N. S. Tonchev

The scaling properties of the free energy and some of universal amplitudes of a group of models belonging to the universality class of the quantum nonlinear sigma model and the O(n) quantum $ϕ^4$ model in the limit $n\to \infty$ as well as the quantum spherical model, with nearest-neighbor and long-range interactions (decreasing at long distances $r$ as $1/r

C. W. J. Beenakker, M. Patra, P. W. Brouwer

This is a theory for the effect of localization on the super-Poissonian noise of radiation propagating through an absorbing disordered waveguide. Localization suppresses both the mean photon current I and the noise power P, but the Fano factor P/I is found to remain unaffected. For strong absorption the Fano factor has the universal value 1+3f/2 (with f the

I. V. Stasyuk, O. V. Velychko, Z. Czapla, R. Czukwinski

A simple description of thermodynamics of DMAAS and DMAGaS ferroelectric crystals by means of Landau expansion is proposed. Conditions of occurrence of phase transitions are established and their temperatures are obtained. The influence of external hydrostatic pressure on phase transitions is described. The temperature behaviour of dielectric susceptibility

Kristinn Johnsen

We study theoretically the optics in undoped direct gap semiconductors which are strongly driven in the THz regime. We calculate the optical sideband generation due to nonlinear mixing of the THz field and the near infrared probe. Starting with an inversion symmetric microscopic Hamiltonian we include the THz field nonperturbatively using non-equilibrium Gre

Martin Petersilka, E. K. U. Gross, Kieron Burke

The role of the exchange-correlation potential and the exchange-correlation kernel in the calculation of excitation energues from time-dependent density functional theory is studied. Excitation energies of the He and Be atoms are calculated, both from the exact ground-state Kohn-Sham potential, and from two orbital-dependent approximations. These are exact e

Kieron Burke, Martin Petersilka, E. K. U. Gross

A review of the approximations in any time-dependent density functional calculation of excitation energies is given. The single-pole approximation for the susceptibility is used to understand errors in popular approximations for the exchange-correlation kernel. A new hybrid of exact exchange and adiabatic local density approximation is proposed and tested on

D. V. Bizyaev

We used three indicators of massive star formation: $H_α$, FIR and non-thermal radio luminosities, to compare estimations of Star Formation Rate (SFR) for the sample of 34 spiral galaxies. To adjust SFR values, obtained from different indicators, we considered the slope $α$ and/or upper mass limit $M_{up}$ of Initial Mass Function (IMF) as free parameters. T

J. R. D. Lepine, Yu. N. Mishurov, S. Yu. Dedikov

We investigate the possibility of describing the spiral pattern of the Milky Way in terms of a model of superposition 2- and 4-armed wave harmonics (the simplest description, besides pure modes). Two complementary methods are used: a study of stellar kinematics, and direct tracing of positions of spiral arms. In the first method, the parameters of the galact

M. E. van den Ancker, P. R. Wesselius, A. G. G. M. Tielens

We present the results of ISO SWS and LWS grating scans towards the three brightest members of the BD+40 4124 group in the infrared: BD+40 4124 (B2Ve), LkHalpha 224 (A7e) and the embedded source LkHalpha 225. Emission from the pure rotational lines of H_2, from ro-vibrational transitions of CO, from PAHs, from H I recombination lines and from the infrared fi

A. A. Esin, J. -P. Lasota, R. I. Hynes

We show that the 1996 outburst of the X-ray binary transient system GRO J1655-40 can be explained by the standard dwarf-nova type disc instability, followed by an episode of enhanced mass transfer from the secondary if the mass transfer rate in GRO J1655-40 is within a factor < 10 of the stability limit. We argue that irradiation of the secondary during the

Harald Kuntschner

We have measured central line strengths for a magnitude-limited sample of early-type galaxies in the Fornax cluster, comprising 11 elliptical (E) and 11 lenticular (S0) galaxies, more luminous than MB=-17. When compared with single-burst stellar population models we find that the centres of Fornax ellipticals follow a locus of fixed age and have metallicitie

T. P. Roberts, R. S. Warwick

We use the extensive public archive of ROSAT High Resolution Imager (HRI) observations to carry out a statistical investigation of the X-ray properties of nearby galaxies. Specifically we focus on the sample of 486 bright (B_T < 12.5) northern galaxies studied by Ho, Filippenko and Sargent (HFS) in the context of their exploration of the optical spectroscopi

S. Basu, S. Turck-Chieze, G. Berthomieu, A. S. Brun

Recent studies have established that peaks in solar oscillation power spectra are not Lorentzian in shape, but have a distinct asymmetry. Fitting a symmetric Lorentzian profile to the peaks therefore produces a shift in frequency of the modes. Accurate determination of low-frequency modes is essential to infer the structure of the solar core by inversion of

Claudia Winge, Thaisa Storchi-Bergmann, Martin J. Ward, Andrew S. Wilson

Results from an analysis of low resolution (R~250) near-IR long-slit spectra covering simultaneously the I, J, H, and K bands, for a sample of 15 Seyfert galaxies and the N5253 starburst nucleus, are presented. The Seyfert galaxies were selected as presenting `linear&#39; or cone-like high excitation emission line in the optical, most probably due to the col

K. T. Chyzy, R. Beck, S. Kohle, U. Klein

We present a high-resolution VLA study of the total power and polarized radio continuum emission at 8.46 and 4.86 GHz of the irregular galaxy NGC 4449, known for its weak rotation and non-systematic gas motions. We found strong galaxy-scale regular magnetic fields, which is surprising because of a lack of ordered rotation required for the dynamo action. The

W. Collmar, O. Reimer, K. Bennett, H. Bloemen

The Compton Gamma-Ray Observatory (CGRO) experiments EGRET and COMPTEL observed the Virgo sky region continuously for 7 weeks between December 10, 1996 and January 28, 1997. The prominent quasar 3C~273 was found to be the brightest source in gamma-rays and was significantly detected by EGRET and COMPTEL. The EGRET experiment observed a time-variable flux at

Kristen Menou, Jean-Marie Hameury, Jean-Pierre Lasota, Ramesh Narayan

We construct time-dependent models of accretion discs around black holes and neutron stars. We investigate the effect of evaporating the disc inner regions during quiescence on the predictions of the Disc Instability Model (DIM) for these systems. We do not include irradiation of the disc in the models. Removing the inner, most unstable parts of the accretio

F. Nicastro, L. Piro, A. De Rosa, M. Feroci

NGC 5548 was observed by BeppoSAX in a single long (8 day) observation from 0.2 to 200 keV. We find (1) the spectral variation of the source is produced by a change of the intrinsic power law slope; (2) a high energy cut-off at $E_c= 115^{+39}_{-27}$ keV with a hint of change of $E_c$ with flux; (3) OVII and OVIII absorption K edges, and a possible blended O

E. Egami, G. Neugebauer, B. T. Soifer, K. Matthews

We present Keck high-resolution near-IR (2.2 microns; FWHM~0.15&#34;) and mid-IR (12.5 microns; FWHM~0.4&#34;) images of APM08279+5255, a z=3.91 IR-luminous BALQSO with a prodigious apparent bolometric luminosity of 5x10^{15} Lsun, the largest known in the universe. The K-band image shows that this system consists of three components, all of which are likely

Zheng Zheng, Andrew Gould

The two outer triangular caustics (regions of infinite magnification) of a close binary microlens move much faster than the components of the binary themselves, and can even exceed the speed of light. When $ε> 1$, where $εc$ is the caustic speed, the usual formalism for calculating the lens magnification breaks down. We develop a new formalism that makes use

S. S. Larsen, T. Richtler

We present an analysis of correlations between integrated properties of galaxies and their populations of young massive star clusters. Data for 21 nearby galaxies presented by Larsen & Richtler (1999) are used together with literature data for 10 additional galaxies, spanning a range in specific U-band luminosity T_L(U) from 0 to 15. We find that T_L(U) corr

Ch. Helm, A. Odagawa, M. Sakai, H. Adachi

Thin stacks consisting of a single intrinsic Josephson junction on (Bi,Pb)-Sr-Ca-Cu-O thin films are investigated under the influence of external microwave fields. The $I$-$V$-characteristic shows a single resistive branch, a clear superconducting gap edge structure and a pronounced current step in external microwave fields. With increasing irradiation power