February 2001 arXiv papers — page 6

Maria Peressi, Luciano Colombo, Stefano de Gironcoli

The mechanism determining the band alignment of the amorphous/crystalline Si heterostructures is addressed with direct atomistic simulations of the interface performed using a hierarchical combination of various computational schemes ranging from classical model-potential molecular dynamics to ab-initio methods. We found that in coordination defect-free samp

Danny Birmingham, Ivo Sachs, Siddhartha Sen

In this review, we summarize exact results for the three-dimensional BTZ black hole. We use rigorous mathematical results to clarify the general structure and properties of this black hole spacetime and its microscopic description. In particular, we study the formation of the black hole by point particle collisions, leading to an exact analytic determination

Carsten Raas, Alexander Bühler, Götz S. Uhrig

We investigate the anti-adiabatic limit of an anti-ferromagnetic S=1/2 Heisenberg chain coupled to Einstein phonons. The flow equation method is used to decouple the spin and the phonon part of the Hamiltonian. In the effective spin model long range spin-spin interactions are generated. We determine the phase transition from a gapless state to a gapped (dime

Markus Lazar

We give the geometric Wandzura-Wilczek-type relations between the meson wave functions of dynamical twist by means of the meson wave functions of geometric twist. We discuss the difference between geometric and dynamical Wandzura-Wilczek-type relations. Additionally, the interrelations between the different twist notations of meson wave functions are discuss

Th. Koschny, H. Potempa, L. Schweitzer

The disorder driven quantum Hall to insulator transition is investigated for a two-dimensional lattice model. The Hall conductivity and the localization length are calculated numerically near the transition. For uncorrelated and weakly correlated disorder potentials the current carrying states are annihilated by the negative Chern states originating from the

T. Koide, M. Maruyama, F. Takagi

We apply the projection operator method (POM) to $ϕ^4$ theory and derive both quantum and semiclassical equations of motion for the soft modes. These equations have no time-convolution integral term, in sharp contrast with other well-known results obtained using the influence functional method (IFM) and the closed time path method (CTP). However, except for

N. Otuka, P. K. Sahu, M. Isse, Y. Nara

We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65+65 A GeV by using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show

M. Foygel, Alexey Yamilov, Lev I. Deych, A. A. Lisyansky

We study the local states within the polariton bandgap that arise due to deep defect centers with strong electron-phonon coupling. Electron transitions involving deep levels may result in alteration of local elastic constants. In this case, substantial reversible transformations of the impurity polariton density of states occur, which include the appearance/

Hiroyuki Yamashita

We study quantum corrections on four derivative term of vector multiplets in ${\cal{N}}=2$ supersymmetric Yang-Mills theory. We first show splitting of quantum correction on gauge neutral hypermultiplets from U(1) vector multiplets at four derivative order. We then revisit the non-renormalization theorem given by N. Seiberg and M. Dine and show the non-renor

J. M. An, W. E. Pickett

A series of calculations on MgB2 and related isoelectronic systems indicates that the layer of Mg(2+) ions lowers the non-bonding B "pi" (p_z) bands relative to the bonding "sigma" (sp_xp_y) bands compared to graphite, causing sigma --> pi charge transfer and sigma band doping of 0.13 holes/cell. Due to their two dimensionality the sigma band

Stanley L. Robertson, Darryl J. Leiter

We present evidence that the power law part of the quiescent x-ray emissions of neutron stars in low mass x-ray binaries is magnetospheric in origin. It can be very accurately calculated from known rates of spin and magnetic moments determined from the the $\sim 10^{3 - 4}$ times brighter luminosity at the transition to the hard spectral state. This strongly

G. E. Brown, A. Heger, N. Langer, C. -H. Lee

The discrepancy in the past years of many more black-hole soft X-ray transients (SXTs), of which a dozen have now been identified, had challenged accepted wisdom in black hole evolution. The sheer number of inferred SXTs requires that many, if not most, stars of ZAMS masses $20-35\msun$ end up as black holes (Portegies Zwart et al. 1997; Ergma & van den Heuv

Adrian Kent, David Wallace

We investigate quantum interrogation techniques which allow imaging information about semi-transparent objects to be obtained with lower absorption rates than standard classical methods. We show that a gain proportional to log N can be obtained when searching for defects in an array of N pixels, if it is known that at most M of the pixels can have transparen

G. Vidal, R. F. Werner

We present a measure of entanglement that can be computed effectively for any mixed state of an arbitrary bipartite system. We show that it does not increase under local manipulations of the system, and use it to obtain a bound on the teleportation capacity and on the distillable entanglement of mixed states.

Serge Massar, Graeme Mitchison, Stefano Pironio

We show that it is not possible to discriminate two close transparencies without a certain number of photons being absorbed. We extend this to the discrimination of patterns of transparency (images).

Bill Dalton

We use trajectory calculations to successfully explain two-photon "ghost" diffraction, a phenomenon previously explained via quantum mechanical entanglement. The diffraction patterns are accumulated one photon pair at a time. The calculations are based on initial correlation of the trajectories in the crystal source and a trajectory-wave ordering int

Hideo Kosaka, Andrey A. Kiselev, Filipp A. Baron, Ki Wook Kim

An entanglement-preserving photo-detector converts photon polarization to electron spin. Up and down spin must respond equally to oppositely polarized photons, creating a requirement for degenerate spin energies, ge=0 for electrons. We present a plot of ge-factor versus lattice constant, analogous to bandgap versus lattice constant, that can be used for g-fa

V. Berejnov, O. M. Lavrenteva, A. Nir

The axisymmetric deformation and motion of interacting droplets in an imposed temperature gradient is considered using boundary-integral techniques for slow viscous motion. Results showing temporal drop motion, deformations and separation are presented for equal-viscosity fluids. The focus is on cases when the drops are of equal radii or when the smaller dro

A. F. Borghesani

We report measurements of excess electron mobility in dense Argon gas at the two temperatures $T=152.15$ and 162.30 K, fairly close to the critical one ($T_c =150.7$ K), as a function of the gas density $N$ up to 14 atoms$\cdot$nm$^{-3}$ ($N_{c}=8.08$ atoms$\cdot$nm$^{-3}$). For the first time a maximum of the zero-field density-normalized mobility $μ_{0}N$

S. G. Porsev, M. G. Kozlov, Yu. G. Rakhlina, A. Derevianko

To support efforts on cooling and trapping of alkaline-earth atoms and designs of atomic clocks, we performed ab initio relativistic many-body calculations of electric-dipole transition amplitudes between low-lying states of Mg, Ca, and Sr. In particular, we report amplitudes for ^1P_1 --> ^1S_0, ^3S_1, ^1D_2$, for ^3P_1 --> ^1S_0, ^1D_2, and for ^3P_2 --> ^

R. Anni

A simple analytical expression, which closely approximates the Coulomb potential between two uniformly charged spheres, is presented. This expression can be used in the optical potential semiclassical analyses which require that the interaction be analytic on and near the real r-axis.

A. E. Kudryavtsev, V. E. Tarasov

It is shown that, if isospin is not conserved in $a^0_0$- and $f_0$-meson mixing, forward-backward asymmetry arises in the reaction $pn\to da^0_0$. This effect increases near the reaction threshold. The asymmetry is estimated within the framework of a model in which the $a^0_0$-$f_0$ mixing is due to the virtual $π^0\leftrightarrowη$ transition and the diffe

Jian-Ye Liu, Yan-Fang Yang, Wei Zuo, Shun-Jin Wang

In the simulation of intermediate energy heavy ion collisions by using the isospin dependent quantum molecular dynamics, the isospin effect on the process of multifragmentation and dissipation has been studied. It is found that the multiplicity of intermediate mass fragments $N_{imf}$ for the neutron-poor colliding system is always larger than that for the n

F. Coester, W. N. Polyzou

Relativistic quantum dynamics requires a unitary representation of the Poincare group on the Hilbert space of states. The dynamics of many-body systems must satisfy cluster separability requirements. In this paper we formulate an abstract framework of four dimensional Euclidean Green functions that can be used to construct relativistic quantum dynamics of N-

I. G. Bearden

3pi- correlations from Pb+Pb collisions at 158 GeV/c per nucleon are presented as measured by the focusing spectrometer of the NA44 experiment at CERN. The three-body effect is found to be stronger for PbPb than for SPb. The two-dimensional three-particle correlation function is also measured and the longitudinal extension of the source is larger than the tr

Rusty S. Towell

A precise measurement of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on liquid hydrogen and deuterium targets is reported. Over 370,000 Drell-Yan muon pairs were recorded. From these data, the ratio of anti-down ($\bar{d}$) to anti-up ($\bar{u}$) quark distributions in the proton sea is determined over a wide range in Bjorken-x. A st

Boris Chirikov, Oleg Zhirov

The structure of very complicated irregular "microscopic" (local) entropy fluctuations around a big separated "macroscopic" (global) fluctuation in the statistical equilibrium was studied in numerical experiments on a simple 2--freedom strongly chaotic Hamiltonian model described by the modified Arnold cat map. A comparison of transient noneq

K. Nishinari, J. Matsukidaira, D. Takahashi

A two-dimensional cellular automaton(CA) associated with a two-dimensional Burgers equation is presented. The 2D Burgers equation is an integrable generalization of the well-known Burgers equation, and is transformed into a 2D diffusion equation by the Cole-Hopf transformation. The CA is derived from the 2D Burgers equation by using the ultradiscrete method,

A. G. Ramm

Let $lu = -u^{\prime \prime} + q(x)u$, where $q(x)$ is a real-valued $L^2_{loc}(0, \infty)$ function. H. Weyl has proved in 1910 that for any $z$, $Imz \neq 0$, the equation $(l - z)w=0$, $x>0$, has a solution $w \in L^2(0, \infty)$. We prove this classical result using a new argument.

A. G. Ramm

Let $u_t = u_{xx} - q(x) u, 0 \leq x \leq 1$, $t>0$, $u(0, t) = 0, u(1, t) = a(t), u(x,0) = 0$, where $a(t)$ is a given function vanishing for $t>T$, $a(t) \not\equiv 0$, $\int^T_0 a(t) dt < \infty$. Suppose one measures the flux $u_x (0,t) := b_0 (t)$ for all $t>0$. Does this information determine $q(x)$ uniquely? Do the measurements of the flux $u_x (1,t)

J. Dimock

We study the covariant free bosonic string field theory and explore its locality (causality) properties. We find covariant string fields which are strictly local and covariant, but act on an unconstrained Hilbert space with an indefinite inner product. From these we also define observable fields which act on the physical Hilbert space with an definite inner

A. Odzijewicz, A. Ryzko

Using the q-version of the Darboux transform we obtain the general solution of q-difference Riccati equation from a special one by the action of one-parameter group. This allows us to construct the solutions for the latge class of q-difference Riccati equations as well as q-difference Schrodinger equations

Ali Ulas Ozgur Kisisel

This paper investigates Hamiltonian properties of the algebro-geometric discretization of KP hierarchy introduced in \cite{Gie1}. A Poisson bracket is introduced. The system is related to the periodic band matrix system of \cite{vM-M}. It is shown that the bracket descends to the latter and endows it with bi-Hamiltonian structure together with the first brac

Ali Ulas Ozgur Kisisel

This paper studies a certain completely integrable discretization of the KP hierarchy. This was constructed by Gieseker in \cite{Gie1}, from certain algebro-geometric data. This paper has the dual aim of showing that this construction is generically invertible, and obtaining explicit expressions for the flow equations. A subsequent article will discuss the H

Charles P. Boyer, Krzysztof Galicki, Michael Nakamaye

We show that $\scriptstyle{#9(S^2\times S^3)}$ admits an 8-dimensional complex family of inequivalent non-regular Sasakian-Einstein structures. These are the first known Einstein metrics on this 5-manifold. In particular, the bound $\scriptstyle{b_2(M)\leq8}$ which holds for any regular Sasakian-Einstein $\scriptstyle{M}$ does not apply to the non-regular ca

A. V. Ershov

This paper is the supplement to the section 2 of the paper &#34;Floating bundles and their applications&#34; (math.AT/0102054). Below we construct the denumerable set of extensions of the formal group of geometric cobordisms $F(x\otimes 1,1\otimes x)$ by the Hopf algebra $H=Ω_U^*(Gr).$

Alexander Schmitt

We provide a construction of the moduli spaces of framed Hitchin pairs and their master spaces. These objects have come to interest as algebraic versions of solutions of certain coupled vortex equations by work of Lin and Stupariu. Our method unifies and generalizes constructions of several similar moduli spaces. Here are some points which are also of intere

J. S. Birman, P. Boldi, M. Rampichini, S. Vigna

In their paper `A new algorithm for recognizing the unknot&#39;, in Geometry and Topology&#39;, 2 (1998) n. 9, 175-220, the first author and Michael Hirsch presented a then new algorithm for recognizing the unknot. The first part of the algorithm required the systematic enumeration of all discs which support a `braid foliation&#39; and are embeddable in 3-sp

Denny H. Leung, Wee-Kee Tang

If αand βare countable ordinals such that β\neq 0, denote by \tilde{T}_{α,β} the completion of $c_{00}$ with respect to the implicitly defined norm ||x|| = max{||x||_{c_{0}}, 1/2 sup \sum_{i=1}^{j}||E_{i}x||}, where the supremum is taken over all finite subsets E_{1},...,E_{j} of $\mathbb{N}$ such that $E_{1}<...<E_{j}$ and {min E_{1},...,min E_{j}} \in S_β.

David A. Cox

The revised version has two additional references and a shorter proof of Proposition 5.7. This version also makes numerous small changes and has an appendix containing a proof of the degree formula for a parametrized surface.

Ph. Brax

We study the warped geometry of heterotic M-Theory in five dimensions where five-branes are included in the bulk. Five-branes wrapping holomorphic curves lead to BPS configurations where the junction conditions are automatically satisfied. We consider five-branes wrapped around non-supersymmetric cycles and show that the configuration is unstable. We describ

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

Classical Calogero-Moser models with rational potential are known to be superintegrable. That is, on top of the r involutive conserved quantities necessary for the integrability of a system with r degrees of freedom, they possess an additional set of r-1 algebraically and functionally independent globally defined conserved quantities. At the quantum level, K

Nematollah Riazi

Basic concepts and definitions in differential geometry and topology which are important in the theory of solitons and instantons are reviewed. Many examples from soliton theory are discussed briefly, in order to highlight the application of various geometrical concepts and techniques.

Yi-hong Gao, Zhong-xia Yang

Quantum corrections to the energy of D0-branes in a constant RR 4-form background are studied. Using the Born-Oppenheimer approximation, we compute the long-range interaction between two spherical D2-D0 bound states. We extend this calculation to the case where some mass terms are added. For the special value of masses at which the classical energy vanishes,

R. L. Jaffe

I review what is known about the quark and gluon spin distributions in the nucleon. I discuss in some detail (a) the existence of sum rules for angular momentum; (b) the interpretation and possible measurement of the nucleon&#39;s transversity distributions; and (c) the uses of spin-dependent fragmentation functions.

H. V. Klapdor-Kleingrothaus

The GENIUS (\underline {Ge}rmanium in Liquid \underline {Ni}trogen \underline {U}nderground \underline {S}etup) project has been proposed in 1997 \cite{KK-BEY97} as first third generation double beta decay project, with a sensitivity aiming down to a level of an effective neutrino mass of $<m>\sim$ 0.01 - 0.001 eV. Such sensitivity has been shown to be indis

H. V. Klapdor-Kleingrothaus

Double beta decay is indispensable to solve the question of the neutrino mass matrix together with $ν$ oscillation experiments. The most sensitive experiment - since eight years the HEIDELBERG-MOSCOW experiment in Gran-Sasso - already now, with the experimental limit of $<m_ν> < 0.26$ eV practically excludes degenerate $ν$ mass scenarios allowing neutrinos a

Monika Randhawa, Manmohan Gupta

Motivated by the possibility of the low value of sin2βin the measurements of BABAR and BELLE collaborations, a reference unitarity triangle is constructed using the unitarity of the CKM matrix and the experimental values of the well known CKM elements, without involving any inputs from the processes which might include the new physics effects. The angles of

Kenneth Lane

If the discrepancy between the theoretical and newly measured values of the muon&#39;s anomalous magnetic moment is ascribed to muon substructure, there results an improved model--independent limit on its energy scale, 1.2 TeV < Lambda_mu < 3.2 TeV at 95% C.L.

The DELPHI Collaboration, P. Abreu

A search for the supersymmetric partner of the goldstino, the sgoldstino S, at LEP2 is presented. The production Sgamma followed by S decay into two gluons or into two photons was studied at 189 - 202 GeV LEP centre-of-mass energies. No evidence for the S production was found and limits on the S mass corresponding to different theory parameters are given.

Aleksander Filip Zarnecki

Measurement of the Yukawa couplings of the first-generation leptoquarks has been studied for e+e- collisions at TESLA, at sqrt(s)=800 GeV. By combining measurements from different production and decay channels, determination of Yukawa couplings with precision on the few per-cent level is possible. TESLA will be sensitive to very small leptoquark Yukawa coupl

Lewis H. Ryder, Bahram Mashhoon

Rapporteur&#39;s Introduction to the GT8 session of the Ninth Marcel Grossmann Meeting (Rome, 2000); to appear in the Proceedings.

K Glampedakis, N Andersson

We study the scattering of massless scalar waves by a Kerr black hole by letting plane monochromatic waves impinge on the black hole. We calculate the relevant scattering phase-shifts using the Pruefer phase-function method, which is computationally efficient and reliable also for high frequencies and/or large values of the angular multipole indices (l,m). W

Laurent Freidel

We present the construction of the partition function of 3-dimensional gravity in the Lorentzian regime as a state sum model over a triangulation. This generalize the work of Ponzano and Regge to the case of Lorentzian signature.

A. Mallios, I. Raptis

A locally finite, causal and quantal substitute for a locally Minkowskian principal fiber bundle $\cal{P}$ of modules of Cartan differential forms $\omg$ over a bounded region $X$ of a curved $C^{\infty}$-smooth differential manifold spacetime $M$ with structure group ${\bf G}$ that of orthochronous Lorentz transformations $L^{+}:=SO(1,3)^{\uparrow}$, is pre

Joerg Frauendiener, Christian Klein

This is the third in a series of papers on the construction of explicit solutions to the stationary axisymmetric Einstein equations which can be interpreted as counter-rotating disks of dust. We discuss the physical properties of a class of solutions to the Einstein equations for disks with constant angular velocity and constant relative density which was co

Soumitra SenGupta, Saurabh Sur

Static spherically symmetric solution in a background spacetime with torsion is derived explicitly. The torsion considered here is identified with the field strength of a second rank antisymmetric tensor field namely the Kalb-Ramond field and the proposed solution therefore has much significance in a string inspired gravitational field theory.

L. C. Garcia de Andrade

Closed Time-like curves (CTC) in Cosmic strings in teleparallel $T_{4}$ gravity are forbidden.This result shown here in $T_{4}$ was shown by Soleng (Phys.Rev.D49 (1994)1124) also to be valid in Einstein-Cartan (EC) gravity.Here we show that in $T_{4}$ to allow for CTC we are also led to a lower bound on the angular momentum of the cosmic string.This result i

Ioannis Raptis

A quantum causal topology is presented. This is modeled after a non-commutative scheme type of theory for the curved finitary spacetime sheaves of the non-abelian incidence Rota algebras that represent `gravitational quantum causal sets&#39;. The finitary spacetime primitive algebra scheme structures for quantum causal sets proposed here are interpreted as t

Daniel Albro

Primitive Optimality Theory (OTP) (Eisner, 1997a; Albro, 1998), a computational model of Optimality Theory (Prince and Smolensky, 1993), employs a finite state machine to represent the set of active candidates at each stage of an Optimality Theoretic derivation, as well as weighted finite state machines to represent the constraints themselves. For some purpo

Anja Belz

This paper describes a novel approach to constructing phonotactic models. The underlying theoretical approach to phonological description is the multisyllable approach in which multiple syllable classes are defined that reflect phonotactically idiosyncratic syllable subcategories. A new finite-state formalism, OFS Modelling, is used as a tool for encoding, a

Jason Eisner

We consider the problem of ranking a set of OT constraints in a manner consistent with data. We speed up Tesar and Smolensky&#39;s RCD algorithm to be linear on the number of constraints. This finds a ranking so each attested form x_i beats or ties a particular competitor y_i. We also generalize RCD so each x_i beats or ties all possible competitors. Alas, t

P. Prelovsek, T. Tohyama, S. Maekawa

The Hall constant R_H is considered for the stripe structures. In order to explain the vanishing of R_H in LNSCO at x = 1/8, we use the relation of R_H to the Drude weight D as well as direct numerical calculation, to obtain results within the t-J model, where the stripes are imposed via a charge potential and a staggered magnetic field. The origin of R_H ~

R. Roth, H. Feldmeier

The structure and stability of dilute degenerate Fermi gases trapped in an external potential is discussed with special emphasis on the influence of s- and p-wave interactions. In a first step an Effective Contact Interaction for all partial waves is derived, which reproduces the energy spectrum of the full potential within a mean-field model space. Using th

Sergey A. Vitkalov

Recent experiments in silicon MOSFETs indicate that the Hall coefficient is independent of magnetic field applied at a small angle with respect to the plane. Below a scattering between spin-up and spin-down carriers is considered to be the main reason for the experimental observation. Comparison of two band model with experiment provides an upper limit for t

E. K. Lenzi, C. Anteneodo, L. Borland

We investigate the escape behavior of systems governed by the one-dimensional nonlinear diffusion equation $\partial_t ρ= \partial_x[\partial_x Uρ] + D\partial^2_x ρ^ν$, where the potential of the drift, $U(x)$, presents a double-well and $D, ν$ are real parameters. For systems close to the steady state we obtain an analytical expression of the mean first pa

D. Dulic, A. Pimenov, D. van der Marel, D. M. Broun

We present microwave and infrared measurements on SmLa0.8Sr0.2CuO4-d, which are direct evidence for the existence of a transverse optical plasma mode, observed as a peak in the c-axis optical conductivity. This mode appears as a consequence of the existence of two different intrinsic Josephson couplings between the CuO2 layers, one with a Sm2O2 block layer,

A. Ordemann, E. Tomer, G. Berkolaiko, S. Havlin

Self-attracting walks (SATW) with attractive interaction u > 0 display a swelling-collapse transition at a critical u_{\mathrm{c}} for dimensions d >= 2, analogous to the Θtransition of polymers. We are interested in the structure of the clusters generated by SATW below u_{\mathrm{c}} (swollen walk), above u_{\mathrm{c}} (collapsed walk), and at u_{\mathrm{c

Anke Ordemann, Markus Porto, H. Eduardo Roman, Shlomo Havlin

We study the asymptotic shape of self-avoiding random walks (SAW) on the backbone of the incipient percolation cluster in d-dimensional lattices analytically. It is generally accepted that the configurational averaged probability distribution function <P_{\mathrm{B}}(r,N)> for the end-to-end distance r of an N step SAW behaves as a power law for r -> 0. In t

I. M. Yurin, V. B. Kalinin

In this work the long-wave limit of electron-electron interaction arising from the exchange of virtual phonons in an approximation close to &#34;jelly&#34; model is considered. It is shown that the interaction through the exchange of virtual phonons is actually not screened in contrast to the Coulomb one; this just leads to instability relative to the format

JJ Ramasco, JM Lopez, MA Rodriguez

We study the pinning-depinning phase transition of interfaces in the quenched Kardar-Parisi-Zhang model as the external driving force $F$ goes towards zero. For a fixed value of the driving force we induce depinning by increasing the nonlinear term coefficient $λ$, which is related to lateral growth, up to a critical threshold. We focus on the case in which

A. Rajantie

In superconductors, and in other systems with a local U(1) gauge invariance, there are two mechanisms that form topological defects in phase transitions. In addition to the standard Kibble mechanism, thermal fluctuations of the magnetic field also lead to defect formation. This mechanism is specific to local gauge theories, predicts a qualitatively different

S. Drozdz, J. Kwapien, F. Gruemmer, F. Ruf

A novel application of the correlation matrix formalism to study dynamics of the financial evolution is presented. This formalism allows to quantify the memory effects as well as some potential repeatable intradaily structures in the financial time-series. The present study is based on the high-frequency Deutsche Aktienindex (DAX) data over the time-period b

J. K. Freericks, V. Zlatic&#39;

Many experimental systems exist that possess charge-density-wave order in their ground state. While this order should be able to be described with models similar to those used for superconductivity, nearly all systems have a ratio of the charge-density-wave order parameter to the transition temperature that is too high for conventional theories. Recent work

H. Kontani, K. Kanki

This is a reply to the comment by O. Narikiyo (cond-mat/0012505) on our paper J. Phys. Soc. Jpn. {\bf 68}, (1999) 1614. We point out mistakes about his arguments, and we show that our analysis is compatible with the established Fermi liquid theory, so the obtained result is justified.

C. Burstedde, K. Klauck, A. Schadschneider, J. Zittartz

We propose a 2-dimensional cellular automaton model to simulate pedestrian traffic. It is a vmax=1 model with exclusion statistics and parallel dynamics. Long-range interactions between the pedestrians are mediated by a so called floor field which modifies the transition rates to neighbouring cells. This field, which can be discrete or continuous, is subject

Bartolo Luque, Fernando J. Ballesteros, Enrique M. Muro

Standard Random Boolean Networks display an order-disorder phase transition. We add to the standard Random Boolean Networks a disconnection rule which couples the control and order parameters. By this way, the system is driven to the critical line transition. Under the influence of perturbations the system point out self-organized critical behavior. Several

A. Kemper, A. Schadschneider, J. Zittartz

We apply the transfer-matrix DMRG (TMRG) to a stochastic model, the Domany-Kinzel cellular automaton, which exhibits a non-equilibrium phase transition in the directed percolation universality class. Estimates for the stochastic time evolution, phase boundaries and critical exponents can be obtained with high precision. This is possible using only modest num

In-Ho Lee, Sang Boo Nam

The notion of a finite pairing interaction energy range suggested by Nam, results in some states at the Fermi level not participating in pairings when there are scattering centers such as impurities. The fact that not all states at the Fermi level participate in pairing is shown to suppress $T_c$ in an isotropic superconductor and destroy superconductivity.

Regina E. Schulte-Ladbeck, Ulrich Hopp, Laura Greggio, Mary M. Crone

We report the results of near-IR imaging in J and H, of I Zw 36 ($\approx$Z$_{\odot}$/14) with the Hubble Space Telescope. Whereas imaging with the pre-COSTAR Faint Object Camera (FOC) previously resolved hot and massive stars in the near-UV, the NICMOS data furnish a census of the cool, intermediate- and low-mass stars. There clearly was star formation in I

Gillian Wilson, Nick Kaiser, Gerard A. Luppino

We present a weak lensing and photometric study of six half by half degree fields observed at the CFHT using the UH8K CCD mosaic camera. The fields were observed for a total of 2 hours each in I and V, resulting in catalogs containing ~ 20 000 galaxies per passband per field. We use V-I color and I magnitude to select bright early type galaxies at redshifts

L. Homer, Scott F. Anderson, Bruce Margon, Eric W. Deutsch

We have obtained exposures of the field of X0512-401 in the globular cluster NGC1851, in X-rays with the Chandra X-ray Observatory, and in the far-UV with the Hubble Space Telescope. We derive an accurate new X-ray position within ~1&#34; for X0512-401, which enables us to confirm that the only plausible candidate for the optical/UV counterpart is the Star A

Gregory G. Howes, Steven C. Cowley, James C. McWilliams

The effect of magnetic shear and shear flow on local gravitationally induced instabilities is investigated. A simple model is constructed allowing for an arbitrary entropy gradient and a shear plasma flow in the Boussinesq approximation. A transformation to shearing magnetic coordinates achieves a model with plasma flow along the magnetic field lines where t

Ignacio Trujillo, Alister W. Graham, Nicola Caon

This paper addresses some questions which have arisen from the use of the Sérsic r^{1/n} law in modelling the luminosity profiles of early type galaxies. The first issue deals with the trend between the half-light radius and the structural parameter n. We show that the correlation between these two parameters is not only real, but is a natural consequence fr

Sueli M. Viegas

It is well-known that photoionization is the major mechanism powering nebulae emission-lines. For about 30 years, numerical simulations using photoionization codes have been employed to analyze HII regions, planetary nebulae and active galactic nuclei. Although these models can reproduce most of the observed features, some remain unexplained. Two possible ca

HEGRA Collaboration, F. Aharonian

232 hours of data were accumulated from 1997 to 1999, using the HEGRA Stereoscopic Cherenkov Telescope System to observe the supernova remnant Cassiopeia A. TeV gamma ray emission was detected at the 5 sigma level, and a flux of (5.8 +- 1.2(stat) +- 1.2(syst)) 10^(-9) ph m^(-2) s^(-1) above 1 TeV was derived. The spectral distribution is consistent with a po

U. Munari, R. Jurdana-Sepic, D. Moro

The rich plate archive of the Asiago observatory has been searched for plates containing the symbiotic stars AS 323, Ap 3-1, CM Aql, V1413 Aql (=AS 338), V443 Her, V627 Cas (=AS 501) and V919 Sgr. The program objects have been found on 602 plates, where their brightness has been estimated against the UBVRI photometric sequences calibrated by Henden and Munar

G. Carraro, F. Patat, H. Baumgardt

We report on UBVRI photometry of two $5^{\prime} \times 5^{\prime}$ fields in the region of the young open cluster NGC 3324. One of our fields covers the core region, while the other is closer to the tidal radius of the cluster. Our study provides the first CCD photometry of NGC 3324. We find that the cluster is very young and probably contains several pre M

A. Goldwurm, P. Goldoni, A. Gros, J. Stephen

The IBIS telescope onboard INTEGRAL, the ESA gamma-ray space mission to be launched in 2002, is a soft gamma-ray (20 keV - 10 MeV) device based on a coded aperture imaging system. We describe here basic concepts of coded masks, the imaging system of the IBIS telescope, and the standard data analysis procedures to reconstruct sky images. This analysis include

V. Korchagin, Y. D. Mayya, E. I. Vorobyov

We compute radial color gradients produced by an outwardly propagating circular wave of star formation and compare our results with color gradients observed in the classical ring galaxy, the ``Cartwheel&#39;&#39;. We invoke two independent models of star formation in the ring galaxies. The first one is the conventional density wave scenario, in which an intr

V. N. Shalyapin

The monitoring of the gravitational lens Q2237+0305 carried out by the OGLE group during 1997--1999 is analyzed. The significant light amplifications in the C and A quasar components with maxima in mid- and late 1999, respectively, are interpreted as the crossing of microlens caustics by the source. A constraint on the emitting-region size R < 10^(15) cm has

T. Bloecker, R. Osterbart, G. Weigelt, Y. Balega

Structural and chemical changes during the AGB and post-AGB evolution are discussed with respect to two recent observational and theoretical findings. On the one hand, high-resolution infrared observations revealed details of the dynamical evolution of the fragmented, bipolar dust shell around the far-evolved carbon star IRC+10216 giving evidence for rapid c

A. Goldwurm

The Center of our Galaxy is a peculiar region where a number of crucial astrophysical phenomena take place, from star formation to SN explosions and accretion onto a massive black hole. The quest for a massive black hole in the Galactic Nucleus is of course of particular relevance because, it would be the closest of such extreme objects, which are now believ

Alex Lazarian, Dmitri Pogosyan, Enrique Vazquez-Semadeni, Barbara Pichardo

In this paper we test the results of a recent analytical study by Lazarian and Pogosyan, on the statistics of emissivity in velocity channel maps, in the case of realistic density and velocity fields obtained from numerical simulations of MHD turbulence in the interstellar medium (ISM). To compensate for the lack of well-developed inertial ranges in the simu

M. Orito, T. Kajino, G. J. Mathews, R. N. Boyd

We reanalyze the cosmological constraints on the existence of a net universal lepton asymmetry and neutrino degeneracy. We show that neutrinos can begin to decouple at higher temperatures than previous estimates due to several corrections which diminish the neutrino reaction rate. These decoupled neutrinos are therefore not heated as the particle degrees of

Mingliang Cai, Gregory J. Galloway

Over the past decade there has been an increasing interest in the study of black holes, and related objects, in higher (and lower) dimensions, motivated to a large extent by developments in string theory. The aim of the present paper is to obtain higher dimensional analogues of some well known results for black holes in 3+1 dimensions. More precisely, we obt

Ichiro Oda

We explore the possibility of generalizing the locally localized gravity model in five space-time dimensions to arbitrary higher dimensions. In a space-time with negative cosmological constant, there are essentially two kinds of higher-dimensional cousins which not only take an analytic form but also are free from the naked curvature singularity in a whole b

D. G. Cerdeno, E. Gabrielli, S. Khalil, C. Munoz

We analyze different phenomenological aspects of D-brane constructions. First, we obtain that scenarios with the gauge group and particle content of the supersymmetric standard model lead naturally to intermediate values for the string scale, in order to reproduce the value of gauge couplings deduced from experiments. Second, the soft terms, which turn out t

ZEUS Collaboration

Dijet production has been studied in neutral current deep inelastic e+p scattering for 470 < Q**2 < 20000 GeV**2 with the ZEUS detector at HERA using an integrated luminosity of 38.4 pb**{-1}. Dijet differential cross sections are presented in a kinematic region where both theoretical and experimental uncertainties are small. Next-to-leading-order (NLO) QCD

W. M. Alberico, S. M. Bilenky, C. Maieron

After the EMC and subsequent experiments at CERN, SLAC and DESY on the deep inelastic scattering of polarized leptons on polarized nucleons, it is now established that the Q^2=0 value of the axial strange form factor of the nucleon, a quantity which is connected with the spin of the proton and is quite relevant from the theoretical point of view, is relative