December 2001 arXiv papers — page 15

Alexandre Arbey, Julien Lesgourgues, Pierre Salati

A complex scalar field has recently been suggested to bind galaxies and flatten the rotation curves of spirals. Its cosmological behavior is thoroughly investigated here. Such a field is shown to be a potential candidate for the cosmological dark matter that fills up a fraction Omega_cdm = 0.3 of the Universe. However, problems arise when the limits from gal

M. L. McConnell, A. A. Zdziarski, K. Bennett, H. Bloemen

We have used observations of Cygnus X-1 from the Compton Gamma-Ray Observatory (CGRO) and BeppoSAX to study the variation in the MeV gamma-ray emission between the hard and soft spectral states, using spectra that cover the energy range 20 keV up to 10 MeV. These data provide evidence for significant spectral variability at energies above 1 MeV. In particula

Marton Balazs

We compute the growth fluctuations in equilibrium of a wide class of deposition models. These models also serve as general frame to several nearest-neighbor particle jump processes, e.g. the simple exclusion or the zero range process, where our result turns to current fluctuations of the particles. We use martingale technique and coupling methods to show tha

A. Ivanchik, E. Rodriguez, P. Petitjean, D. Varshalovich

We estimate the cosmological variation of the proton-to-electron mass ratio μ=m_p/m_e by measuring the wavelengths of molecular hydrogen transitions in the early universe. The analysis is performed using high spectral resolution observations (FWHM ~ 7 km/s) of two damped Lyman-αsystems at z_{abs}=2.3377 and 3.0249 observed along the lines of sight to the qua

Pei Herng Hor, Young Hoon Kim

We have studied the charge dynamics of Sr-doped La2CuO4 at hole concentration p =0.07. We observed a clear indication of the competition between two new characteristic collective modes of the Wigner lattice orders suggested earlier: one corresponds to a Tc =15 K superconductivity and the other to Tc =30 K. Our results naturally explain the recent observation

P. B. Ivanov

The formation rate of a close binary consisting of a super-massive black hole and a compact object (presumably a white dwarf) in galactic cusps is calculated with help of the so-called loss cone approximation. For a power low cusp of radius $r_{a}$, the black hole mass $M\sim 10^{6}M_{\odot}$, this rate $\dot N_{wd}\sim 4\cdot 10^{-5}K(p}\sqrt{{GM\over r_{a}

Mihai Dima, James Barron, Anthony Johnson, Luke Hamilton

The determination of the masses of Supersymmetric particles such as the Selectron for energies above threshold using the energy end-points method is subject to signal deconvolution difficulties and to Standard Model and Supersymmetric backgrounds. The important features of Right and Left Selectron production are used to design an experimentally robust method

Eduardo Cuervo-Reyes, Marcos Rigol, Jesus Rubayo-Soneira

Hadron spectra and other properties of quark systems are studied in the framework of a non-relativistic spin-independent phenomenological model. The chosen confining potential is harmonic, which allowed us to obtain analytical solutions for both meson and baryon (of equal constituent quarks) spectra. The introduced parameters are fixed from the low-lying lev

Henning Heiselberg, Ben Mottelson

The shell structures for weakly interacting fermions in harmonic oscillator traps at zero temperature undergo several transitions depending on the number of particles in the trap and their interaction strength. Calculations of the one and two particle spectra give the pairing gaps, and the many particle state is constructed by the seniority scheme. For suffi

Laura Andrianopoli

We discuss the reduction of N=2 supergravity to N=1, by a consistent truncation of the second gravitino multiplet.

Yasushi Ikebe, Thomas H. Reiprich, Hans Boehringer, Yasuo Tanaka

We present a newly measured X-ray temperature function of galaxy clusters using a complete flux-limited sample of 61 clusters. The sample is constructed with the total survey area of 8.14 steradians and the flux limit of 1.99e-11 ergs/s/cm^2 in the 0.1-2.4keV band. X-ray temperatures and fluxes of the sample clusters were accurately measured with ASCA and RO

Konstadinos Sfetsos

There is remarkable relation between self-dual Yang-Mills and self-dual Einstein gravity in four Euclidean dimensions. Motivated by this we investigate the Spin(7) and G_2 invariant self-dual Yang-Mills equations in eight and seven Euclidean dimensions and search for their possible analogs in gravitational theories. The reduction of the self-dual Yang-Mills

Oron Zachar, Igor Zaliznyak

We introduce a general model for understanding the effect of quenched disorder on charge ordering in half-doped Manganese- and Cobalt-Oxides with different crystal structures. Current experimental results (Table-1) are discussed in light of the global phase diagram of the model (Fig. 2).

Ilidio Lopes, Joseph Silk

The experimental uncertainties in G between different experiments have important implications for helioseismology. We show that these uncertainties for the standard solar model lead to a range in the value of the square of the sound speed in the nuclear region that is as much as 0.15% higher than the inverted helioseismic sound speed. While a lower value of

Yoji Osaki, Friedrich Meyer

Photometric humps in outburst that are locked with the binary orbital period have been observed exclusively in the early phase of outbursts of WZ Sge stars. It is suggested that this "early hump" phenomenon is the manifestation of the tidal 2:1 resonance in accretion disks of binary systems with extremely low mass ratios. The "early humps" ca

V. Garzo, J. M. Montanero

The Navier-Stokes transport coefficients of a granular gas are obtained from the Chapman-Enskog solution to the Boltzmann equation. The granular gas is heated by the action of an external driving force (thermostat) which does work to compensate for the collisional loss of energy. Two types of thermostats are considered: (a) a deterministic force proportional

Hiroyuki Kawamura, Jiro Kodaira, Cong-Feng Qiao, Kazuhiro Tanaka

In the heavy-quark limit, the valence Fock-state components in the B mesons are described by a set of two light-cone wavefunctions. We show that these two wavefunctions obey simple coupled differential equations, which are based on the equations of motion in the Heavy Quark Effective Theory (HQET), and the analytic solutions for them are obtained. The result

Ben-Hao Sa, Xu Cai, Zong-Di Su, An Tai

Using a hadron and string cascade model, JPCIAE, we investigated the dependence of event-by-event charge fluctuation on the energy, centrality, window size, resonance decay, and the final state interaction for $Pb+Pb$ collisions at SPS and LHC energies and $Au+Au$ collisions at RHIC energies. The JPCIAE results of charge fluctuation as a function of the rapi

V. P. Nair

Noncommutative three-dimensional gravity can be described in terms of a noncommutative Chern-Simons theory. We extend this structure and also propose an action for gravitational fields on an even dimensional noncommutative space. The action is worked out in some detail for fields on a noncommutative ${\bf CP}^2$ and on $S^4$.

Sergiu I. Vacaru, D. Singleton

In this paper we use the anholonomic frames method to construct exact solutions for vacuum 5D gravity with metrics having off-diagonal components. The solutions are in general anisotropic and possess interesting features such as an anisotropic warp factor with respect to the extra dimension, or a gravitational scaling/running of some of the physical paramete

Jay D. Salmonson, Titus J. Galama

A correlation is presented between the pulse lag and the jet-break time for seven BATSE gamma-ray bursts with known redshifts. This is, to our best knowledge, the first known direct tight correlation between a property of the gamma-ray burst phase (the pulse lag) and the afterglow phase (the jet-break time). As pulse lag and luminosity have been found to be

Aaron Sokasian, Tom Abel, Lars. E. Hernquist

We study the reionization of Helium II by quasars using a numerical approach that combines 3D radiative transfer calculations with cosmological hydrodynamical simulations. Sources producing the ionizing radiation are selected according to an empirical quasar luminosity function and are assigned luminosities according to their intrinsic masses. We present mod

Vittorio Giovannetti, Seth Lloyd, Lorenzo Maccone

We present a system to measure the distance between two parties that allows only trusted people to access the result. The security of the protocol is guaranteed by the complementarity principle in quantum mechanics. The protocol can be realized with available technology, at least as a proof of principle experiment.

Almut Beige, Christian Schoen, Jiannis Pachos

We discuss an experimental setup where two laser-driven atoms spontaneously emit photons and every photon causes a ``click'' at a point on a screen. By deriving the probability density for an emission into a certain direction from basic quantum mechanical principles we predict a spatial interference pattern. Similarities and differences with the clas

Mark P. Davidson

Stochastic field equations for linearized gravity are presented. The theory is compared with the usual quantum field theory and questions of Lorentz covariance are discussed. The classical radiation approximation is also presented.

J. M. Isidro

It has been established that endowing classical phase space with a Riemannian metric is sufficient for describing quantum mechanics. In this letter we argue that, while sufficient, the above condition is certainly not necessary in passing from classical to quantum mechanics. Instead, our approach to quantum mechanics is modelled on a statement that closely r

N. Kamikubota, K. Furukawa, S. Kusano, T. Obata

As an accelerator control system survives over several years, it is often the case that new subsystems are introduced into the original control system. The control system for the KEK electron/positron injector-linac has been using Unix workstations and VME computers since 1993. During the eight-year operation, we extended the system by introducing a) Windows

J. F. Geurdes

In the present paper a counter-example to Bell's theorem is given which is based on common probability densities as standard normal (Gaussian) and uniform probability densities. The reason for violating the Bell inequalities lies in the 'softening' of functions similar to the Dirac delta such that they can be 'hidden' inside a sign functi

C. H. Wang, X. C. Kong, G. Lei, S. F. Xu

We will use EPICS toolkit [1] to build a prototype for upgrading BEPC control system. The purposes are for the following three aspects: (1) Setup a network based distributed control system with EPICS. (2) Study some front-end control technology. (3) Merge the existing control systems into EPICS. The hardware architecture consists of three physical layers. Th

J. C. Pacheco, N. Vinh Mau

We apply a particle-particle RPA model to study the properties of the two-neutron valence wave function in nuclei 14-C, 12-Be, 11-Li and 14-Be. The RPA model takes account of two body correlations in the core so that it gives a better description of energies and amplitudes than models which assume a neutron closed shell (or subshell) core. With a Gogny neutr

B. Kampfer, R. Kotte, C. Hartnack, J. Aichelin

The preliminary experimental data on $ϕ$ production in the reaction Ni(1.93 AGeV) + Ni point to a puzzling high $ϕ$ yield which can not be reproduced with present transport codes. We survey the experimental situation and present prospects for dedicated measurements of the $ϕ$ multiplicities with the $K^+ K^-$ and $e^+ e^-$ channels at HADES and FOPI.

P. Shukla

The Glauber model is extensively applied to heavy ion collision for describing a number of interaction processes over a wide range of energies from near the Coulomb barrier to higher energies. The model gives the nucleus-nucleus interaction in terms of interaction between the constituent nucleons with a given density distribution. The model is a semiclassica

Alberto De Sole, Victor G. Kac

We classify the subalgebras of the general Lie conformal algebra $\gc_N$ that act irreducibly on $\C[\partial]^N$ and that are normalized by the $\operatorname{sl}_2$--part of a Virasoro element. The problem turns out to be closely related to classical Jacobi polynomials $P_n^{(-σ,σ)}$, $σ\in\C$. The connection goes both ways -- we use in our classification

Dirk Hundertmark, Barry Simon

For a Jacobi matrix J on l^2(Z_+) with Ju(n)=a_{n-1} u(n-1) + b_n u(n) + a_n u(n+1), we prove that \sum_{|E|>2} (E^2 -4)^{1/2} \leq \sum_n |b_n| + 4\sum_n |a_n -1|. We also prove bounds on higher moments and some related results in higher dimension.

José F. Cariñena, Héctor Figueroa

The time evolution operator $K$ is introduced in the graded context and its main properties are discussed. In particular, the operator $K$ is used to analize the projectability of constraint functions arising in the Lagrangian formalism for singular Lagrangians.

Friedrich Knop

Let K be a connected Lie group and M a Hamiltonian K-manifold. In this paper, we introduce the notion of convexity of M. It implies that the momentum image is convex, the moment map has connected fibers, and the total moment map is open onto its image. Conversely, the three properties above imply convexity. We show that most Hamiltonian manifolds occuring &#

Vivian De Smedt, Simon Salamon

The aim of the paper is to determine left-invariant,anti-self-dual, non conformally flat, Riemannian metrics on four-dimensional Lie groups.

Cyrille Ospel

For a commutative algebra the shuffle product is a morphism of complexes. We generalize this result to the quantum shuffle product, associated to a class of non-commutative algebras (for example all the Hopf algebras). As a first application we show that the Hochschild-Serre identity is the dual statement of our result. In particular, we extend this identity

Salih Celik, Sultan A. Celik

We introduce a two-parameter deformation of 2x2 matrices without imposing any condition on the matrices and give the universal R-matrix of the nonstandard quantum group which satisfies the quantum Yang-Baxter relation. Although in the standard two-parameter deformation the quantum determinant is not central, in the nonstandard case it is central. We note tha

Salih Celik, Sultan A. Celik

We introduce a noncommutative differential calculus on the two-parameter $h$-superplane via a contraction of the (p,q)-superplane. We manifestly show that the differential calculus is covariant under $GL_{h_1,h_2}(1| 1)$ transformations. We also give a two-parameter deformation of the (1+1)-dimensional phase space algebra.

Salih Celik, Sultan A. Celik

In this paper properties of the quantum supermatrices in the quantum supergroup $GL_{p,q}(1|1)$ are discussed. It is shown that any element of $GL_{p,q}(1|1)$ can be expressed as the exponential of a matrix of non-commuting elements, like the group $GL_q(1|1)$. An explicit construction of this exponential representation is presented.

A. Bella, A. Dow, K. P. Hart, M. Hrusak

Given a Boolean algebra B and an embedding e:B -> P(N)/fin we consider the possibility of extending each or some automorphism of B to the whole P(N)/fin. Among other things, we show, assuming CH, that for a wide class of Boolean algebras there are embeddings for which no non-trivial automorphism can be extended.

Salih Celik, Sultan A. Celik

In this paper, we give the quantum analogue of the dual matrices for the quantum supergroup $GL_q(1|1)$ and discuss these properties of the quantum dual supermatrices.

S. Ishii, P. Milman

This paper shows that an analytic space $X$ has a unique maximal model through which every proper surjective morphism from a non-singular analytic space to $X$ factors. This is called the {\sl geometric minimal model} of $X$ and characterized by the contraction property of rational curves. Some other properties such as functoriality, the direct product prope

Alexander Yong

Fulton and Woodward have recently identified the smallest degree of $q$ that appears in the expansion of the product of two Schubert classes in the (small) quantum cohomology ring of a Grassmannian. We present a combinatorial proof of this result, and provide an alternative characterization of this smallest degree in terms of the rim hook formula for the qua

Thomas W. Mattman

We classify Dehn surgeries on (p,q,r) pretzel knots resulting in a manifold M(s) having cyclic fundamental group and analyze those leading to a finite fundamental group. The proof uses the theory of cyclic and finite surgeries developed by Culler, Shalen, Boyer, and Zhang. In particular, Culler-Shalen seminorms play a central role.

Lek-Heng Lim, Judith A. Packer, Keith F. Taylor

In this paper we use the concept of wavelet sets as introduced by X. Dai and D. Larson, to decompose the wavelet representation of the discrete group associated to an arbitrary $n \times n$ integer dilation matrix as a direct integral of irreducible monomial representations. In so doing we generalize a result of F. Martin and A. Valette in which they show th

D. Palle

We show that the existence of the fundamental ultraviolet cut-off (minimal scale) fixed by weak interactions enhances the QCD running coupling evaluated at one quantum loop level, starting at the scale in the vicinity of the cut-off. The enhancement of the QCD running coupling could completely explain the observed anomalous TeVatron and HERA data. The QCD in

A. Jakovac

In this work a perturbative linear response analysis is performed for the time evolution of the quasi-conserved charge of a scalar field. One can find two regimes, one follows exponential damping, where the damping rate is shown to come from quantum Boltzmann equations. The other regime (coming from multiparticle cuts and products of them) decays as power la

Johann Rafelski

In these remarks I explain the motivation which leads us to consider chemical nonequilibrium processes in flavor equilibration and in statistical hadroniziation of quark--gluon plasma (QGP). Statistical hadronization allowing for chemical non-equilibrium is introduced. The reesults of fits to RHIC-130 results, including multistrange hadrons, are shown to agr

G. Rodrigo, H. Czyz, J. H. Kuhn, M. Szopa

Electron-positron annihilation into hadrons plus an energetic photon from initial state radiation allows the hadronic cross-section to be measured over a wide range of energies. The full next-to-leading order QED corrections for the cross-section for e^+ e^- annihilation into a real tagged photon and a virtual photon converting into hadrons are calculated wh

Siba Prasad Das, Amitava Datta, Monoranjan Guchait

We investigate the prospect of stop squark search at Tevatron RUN-II in mSUGRA motivated as well as unconstrained supersymmetric models, when the lighter stop squark turns out to be the next lightest supersymmetric particle (NLSP). In this case the decay into a 4-body final state consisting of a b quark, the lightest neutralino and two light fermions may com

Paolo Di Vecchia

In this talk we discuss the need to introduce a string theory in order to obtain a consistent quantum theory of gravity unified with gauge interactions. We then discuss some basic properties of string theory and the origin and the properties of the D(irichlet)-branes. Finally we use them for discussing the Maldacena conjecture and its extension to non-confor

I. P. Lokhtin, S. V. Petrushanko, L. I. Sarycheva, A. M. Snigirev

We analyze the azimuthal anisotropy of jet spectra due to energy loss of hard partons in quark-gluon plasma, created initially in nuclear overlap zone in collisions with non-zero impact parameter. The calculations are performed for semi-central Pb-Pb collisions at LHC energy.

A. Bartl, T. Gajdosik, E. Lunghi, A. Masiero

We study FCNC and CP violating processes in the MSSM without a new flavour structure (flavour blind MSSM). The low energy parameters are determined by the running of the soft breaking terms from the GUT scale with SUSY phases consistent with the EDM constraints. We find that the CP asymmetry in b -> s gamma can reach large values potentially measurable at B

Daniel Magestro

This contribution focuses on the results of statistical model calculations at RHIC energies, including recently available experimental data. Previous calculations of particle yield ratios showed good agreement with measurements at SPS and lower energies, suggesting that the composite system possesses a high degree of chemical equilibrium at freeze-out. The e

F. Tessarotto

COMPASS, a new fixed target experiment at CERN, aimed at the study of nucleon spin structure and hadron spectroscopy, has started to collect physics data in Autumn 2001. This paper describes the COMPASS apparatus and the measurement of the gluon polarisation $ΔG /G$. The apparatus consists in a solid state polarised target and a two stage spectro-meter with

I. M. Dremin, P. Edén

Here, we discuss QCD predictions on multiplicities in parton and dipole approaches. The most general treatment is based on the notion of the generating functions. The generating function G is defined as $G(u,y)=\sum_nu^nP_n(y)$, where $P_n$ is the probability of the n-particle production at energy denoted by y, u is an auxiliary variable. The mean multiplici

E. A. De Wolf

Correlations among hadrons with the same electric charge produced in Z$^0$ decays are studied using the high statistics data collected from 1991 through 1995 with the OPAL detector at LEP. Normalized factorial cumulants up to fourth order are used to measure genuine pa rticle correlations as a function of the size of phase space domains in rapidity, azimutha

A. B. Lahanas, D. V. Nanopoulos, V. C. Spanos

In the framework of the Constrained Minimal Supersymmetric Standard Model we discuss the impact of the recent experimental information, especially from the E821 Brookhaven experiment on $g_μ-2$ along with the light Higgs boson mass bound from LEP, in delineating regions of the parameters which are consistent with cosmological data. The effect of these to the

Spencer R. Klein

At very high energies, the bremsstrahlung and pair production cross sections exhibit complex behavior due to the material in which the interactions occur. The cross sections in dense media can be dramatically different than for isolated atoms. This writeup discusses these in-medium effects, emphasizing how the cross section has different energy and target de

Eugen Radu, Dumitru Astefanesei

The behavior of a arbitrary coupled quantum scalar field is studied in the background of the Gödel spacetime. Closed forms are derived for the effective action and the vacuum expectation value of quadratic field fluctuations by using $ζ$-function regularization. Based on these results, we argue that causality violation presented in this spacetime can not be

Moshe Tennenholtz

Much work in computer science has adopted competitive analysis as a tool for decision making under uncertainty. In this work we extend competitive analysis to the context of multi-agent systems. Unlike classical competitive analysis where the behavior of an agent's environment is taken to be arbitrary, we consider the case where an agent's environmen

Naohisa Ogawa, Yoshinori Furukawa

Icicles with wave patterns on their surfaces can sometimes be seen hanging from roofs of buildings. Surprisingly, most of these wave patterns are at intervals of about 1 cm. The reason for this uniformity of interval has not been clarified. Here we show a formula to explain this remarkable phenomenon by introducing a new instability theory. This theory is gi

N. Andrei

Comment on paper by A. Zvyagin, Phys. Rev. B 64, R060405 (2001).

S. S. Botelho, F. D. A. Aarao Reis

We extend a previously proposed deposition model with two kinds of particles, considering the restricted solid-on-solid condition. The probability of incidence of particle C (A) is p (1-p). Aggregation is possible if the top of the column of incidence has a nearest neighbor A and if the difference in the heights of neighboring columns does not exceed 1. For

Mukundan Chakrapani, S. J. Mitchell, D. H. Van Winkle, P. A. Rikvold

Surfaces of surfactant-templated polyacrylamide hydrogels were imaged by atomic force microscopy (AFM), and the surface morphology was studied by numerical scaling analysis. The templated gels were formed by polymerizing acrylamide plus a cross-linker in the presence of surfactants, which were then removed by soaking in distilled water. Gels formed in the pr

Isabel Campos, James W. Davenport

We investigate numerically the magnetic properties of the 3D Isotropic and Anisotropic Hubbard model at half-filling. The behavior of the transition temperature as a function of the anisotropic hopping parameter is qualitatively described. In the Isotropic model we measure the scaling properties of the susceptibility finding agreement with the magnetic criti

D. -X. Chen, J. J. Moreno, A. Hernando, A. Sanchez

We study how the addition of defects in an otherwise uniform Josehpson junction array modifies the critical current of the array, by numerically solving the system of coupled Josephson equations. Our results confirm the existence of two different regimes, depending on the normalized maximum Josephson current of each junction, $i_{\rm max}$: for large $i_{\rm

Y. -J. Wang, F. H. L. Essler, M. Fabrizio, A. A. Nersesyan

We study a two-leg antiferromagnetic spin-1/2 ladder in the presence of a staggered magnetic field. We consider two parameter regimes: strong (weak) coupling along the legs and weak (strong) coupling along the rungs. In both cases, the staggered field drives the Haldane spin-liquid phase of the ladder towards a Gaussian quantum criticality. In a generalized

C. Tordeux, J. -B. Fournier, P. Galatola

We characterize vesicle adhesion onto homogeneous substrates by means of a perturbative expansion around the infinite adhesion limit, where curvature elasticity effects are absent. At first order in curvature elasticity, we determine analytically various global physical quantities associated with adhering vesicles: height, adhesion radius, etc. Our results a

Arnaud Buhot, Avraham Halperin

The force laws governing the extension behavior of homopolypeptides are obtained from a phenomenological free energy capable of describing the helix-coil transition. Just above the melting temperature of the free chains, T*, the plot of force, f, vs. end-to-end distance, R, exhibits two plateaus associated with coexistence of helical and coil domains. The lo

T. M. Gassym

The distribution function of electrons and phonons interacting with electrons in semiconductors and semimetals in high electric and quantizing magnetic fields as a result of the solution of the coupled system of equations for the density matrixes of electrons and phonons is obtained. The effects of heating of electrons and phonons and their arbitrary mutual

A. G. Mal'shukov, V. Shlyapin, K. A. Chao

We have investigated the transport of spin polarization through a classically chaotic semiconductor loop with a strong Rashba spin-orbit interaction. We found that if the escape time of a particle is long enough, the configuration averaged spin conductance oscillates strongly with the geometric spin phase. We predict a sizable rotation of spin polarization a

S. Siljamaki, A. Harju, R. M. Nieminen, V. A. Sverdlov

Using variational quantum Monte Carlo method, the effect of Landau-level mixing on the lowest-energy--state diagram of small quantum dots is studied in the magnetic field range where the density of magnetic flux quanta just exceeds the density of electrons. An accurate analytical many-body wave function is constructed for various angular momentum and spin st

Artem V. Galaktionov, Andrei D. Zaikin

We analyze an interplay between the proximity effect and quantum interference of electrons in hybrid structures superconductor-normal metal-superconductor which contain several insulating barriers. We demonstrate that the dc Josephson current in these structures may change qualitatively due to quantum interference of electrons scattered at different interfac

Yoshiyuki Saito

This papers deals with overall phase transformation kinetics. The Fokker-Planck type equation is derived from the generalized nucleation theory proposed by Binder and Stauffer. Existence of the steady state solution is shown by a method based on the mean value theorem of differential calculus. From the analysis of asymptotic behavior of the Fokker-Planck typ

Vladimir Kobelev, Anatoly B. Kolomeisky, Michael E. Fisher

A theoretical analysis of Coulomb systems on lattices in general dimensions is presented. The thermodynamics is developed using Debye-Huckel theory with ion-pairing and dipole-ion solvation, specific calculations being performed for 3D lattices. As for continuum electrolytes, low-density results for sc, bcc and fcc lattices indicate the existence of gas-liqu

H. M. Bozler, Yuan Gu, Jinshan Zhang, K. S. White

We provide evidence for a finite temperature ferromagnetic transition in 2-dimensions as $H \to 0$ in thin films of $^3$He on graphite, a model system for the study of two-dimensional magnetism. We perform pulsed and CW NMR experiments at fields of 0.03 - 0.48 mT on $^3$He at areal densities of 20.5 - 24.2 atoms/nm$^2$. At these densities, the second layer o

Richard A. Klemm, Marco Ameduri

We reduce the autocorrelation function $C_{11}(t)$ of the equivalent neighbor model of $N$ classical spins exhibiting Heisenberg dynamics and exchange coupling $J$ to quadrature. As the temperature $T\to\infty$, $C_{11}(t)\propto t^{-N}$ for $Jt>>1$. At low $T$, the antiferromagnetic $C_{11}(t)$ is a simple function of $(JT)^{1/2}t$, exhibiting strong frustr

Dmitri S. Golubev, Andrei D. Zaikin, Gerd Schön

The recent claim by Kirkpatrick and Belitz (cond-mat/0111398) that Ward identities could be used to prove the absence of electron dephasing at T=0 contains serious flaws. These authors try to draw conclusions about dephasing from an analysis of the diffuson, which is not sensitive to this process. The Cooperon, which does contain this information, is analyze

Luiz C. de Albuquerque, Marcelo M. Leite

The critical exponents $ν_{L2}, η_{L2}$ and $γ_{L2}$ of a uniaxial Lifshitz point are calculated at two-loop level using renormalization group and $ε_{L}$-expansion techniques. We found a new constraint involving the loop momenta along the competition axis, which allows to solve the two-loop integrals. The exponent $γ_{L2}$ obtained using our method is in go

J. M. De Buizer

The infrared represents an alternative wavelength regime in which to study the environments of maser emission, while at the same time complementing the information obtained through radio techniques. The near infrared (1-2 microns) yields information on outflows, shocks, and reflected dust emission, while the thermal infrared (3-30 microns) yields information

Olaf Wucknitz

We use the radio ring in JVAS B0218+357 to constrain the mass models with LensCLEAN. H0 is determined from the resulting model and the time delay. B0218+357 is one of the best systems to reduce systematic errors in H0 and may thus be called a "golden lens".

S. Chaty, I. F. Mirabel, P. Goldoni, S. Mereghetti

We report on several European Southern Observatory (ESO) near-infrared (NIR) observational campaigns aimed at understanding the nature of galactic black hole candidates. Our results, including NIR photometry of the sources GRO J1655-40, GRS 1739-278, GRS 1716-249, GRS 1121-68 and GX 339-4, show that all the sources but GRO J1655-40 are consistent with low-ma

Knox S. Long, Philip A. Charles, Guillaume Dubus

We have used Hubble Space Telescope to obtain moderate resolution 1150-5700 Ang. spectroscopy of the nucleus of M33 and a blue star ~1 arcsec NNW of the nucleus in an attempt to find the optical counterpart of the nuclear X-ray source and to characterize stellar populations in the nuclear region. The STIS spectra of the nucleus can be modelled in terms of tw

M. Bureau, C. Carignan

Neutral hydrogen VLA D-array observations of the dwarf irregular galaxy HoII, a prototype galaxy for studies of shell formation, are presented. HI is detected to radii over 16' or 4 R_25, and M_HI=6.44x10^8 M_sun. The total HI map has a comet-like appearance suggesting that HoII is affected by ram pressure from an intragroup medium (IGM). A rotation curv

G. G. Pavlov, D. Sanwal, G. P. Garmire, V. E. Zavlin

X-ray images of some young supernova remnants show bright point sources which have not been detected in radio, optical and gamma-ray bands. Despite the similarity of the X-ray spectra of these objects, they show a variety of temporal properties. Most likely, they are neutron stars whose properties (spin periods? magnetic fields? environments?) are different

John J. Salzer, Caryl Gronwall, Vicki L. Sarajedini, Valentin A. Lipovetsky

The KPNO International Spectroscopic Survey (KISS) is an objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors, and is the first purely digital objective-prism survey for emission-line galaxies. Here we present the first list of e

George A. Baker

Recent experimental results from supernovae Ia observations have been interpreted to show that the rate of expansion of the universe is increasing. Other recent experimental results find strong indications that the universe is ``flat.'' In this paper, I investigate some solutions of Einstein's field equations which go smoothly between Schwarzschi

J. M. Oliveira, R. D. Jeffries, M. J. Kenyon, S. A. Thompson

We report on the analysis of 2MASS near-infrared data of a sample of low-mass stars and brown dwarfs in the sigma Orionis cluster. Youth and cluster membership have been spectroscopically confirmed using the Li I spectral line. We find little evidence in the JHKs colour-colour diagram for near-infrared excess emission for these cluster members. By comparison

T. Yaqoob, U. Padmanabhan, T. Dotani, K. Nandra

The ASCA calibration has evolved considerably since launch and indeed, is still evolving. There have been concerns in the literature that changes in the ASCA calibration have resulted in the Fe-Kalpha lines in active galaxies (AGN) now being systematically narrower than was originally thought. If this were true, a large body of ASCA results would be impacted

F. A. Aharonian

The recent developments in studies of TeV radiation from blazars are highlighted and the implications of these results for derivation of cosmologically important information about the cosmic infrared background radiation are discussed.

Nissim Kanekar, Ramana M. Athreya, Jayaram N. Chengalur

We present Giant Metrewave Radio Telescope (GMRT) observations of redshifted 21-cm absorption from the $z=0.437$ metal line absorption system towards PKS 1243-072. HI absorption is clearly detected; the absorption profile has a velocity spread of $\sim 20$ km/s. Detection of 21-cm absorption indicates that the absorber has an HI column density large enough t

M. Aglietta, P. Antonioli, G. Bari, C. Castagnoli

We study the impact of neutrino oscillations on the supernova neutrino signal in the Large Volume Detector (LVD). The number of expected events for a galactic supernova (D=10 kpc) is calculated, assuming neutrino masses and mixing that explain solar and atmospheric neutrino results. The possibility to detect neutrinos in different channels makes LVD sensitiv

V. Beckmann, A. Wolter, A. Celotti, L. Costamante

We present BeppoSAX LECS, MECS, and PDS spectra of eleven X-ray selected BL Lacertae objects. Combining these sources with the ones presented elsewhere we have a sample of 21 BL Lacs from the Einstein Medium Sensitivity and Einstein Slew Survey. The sample shows strong correlations of several physical parameters with the peak frequency of the synchrotron bra

P. Berczik, G. Hensler, Ch. Theis, R. Spurzem

We present our recently developed 3-dimensional chemodynamical code for galaxy evolution. This code follows the evolution of different galactic components like stars, dark matter and different components of the interstellar medium (ISM), i.e. a diffuse gaseous phase and the molecular clouds. Stars and dark matter are treated as collisionless N-body systems.

P. G. Prada Moroni, V. Castellani, S. Degl'Innocenti, M. Marconi

We discuss the CM diagram of the galactic cluster NGC2420 to the light of current theoretical predictions. By relying on the most recent updating of the physical input, one finds too luminous theoretical He burning stars together with the evidence for a misfitting of the lower portion of the MS. Moreover one finds two well known overshooting signatures, as g

M. Ali Alpar

Large pulsar glitches seem to be common to all radio pulsars and to exhibit a universal behaviour connecting the rate of occurrence, event size and interglitch relaxation that can be explained if the glitches are due to angular momentum exchange in the neutron star. This has implications for the energy dissipation rate. The large timing excursions observed i

Edo Noordermeer, Linda S. Sparke, Stephen E. Levine

Lopsidedness is a common feature in galaxies, both in the distribution of light and in the kinematics. We investigate the kinematics of a model for lopsided galaxies that consists of a disc lying off-centre in a dark halo, and circling around the halo centre. We search for families of stable, closed, non-crossing orbits, and assume that gas in our galaxies m