January 2003 arXiv papers — page 13

M. Pioro-Ladriere, M. Ciorga, J. Lapointe, P. Zawadzki

Coulomb and spin blockade spectroscopy investigations have been performed on an electrostatically defined ``artificial molecule'' connected to spin polarized leads. The molecule is first effectively reduced to a two-level system by placing both constituent atoms at a specific location of the level spectrum. The spin sensitivity of the conductance ena

Spiro Karigiannis

We consider some infinitesmal and global deformations of G_2 structures on 7-manifolds. We discover a canonical way to deform a G_2 structure by a vector field in which the associated metric gets "twisted" in some way by the vector cross product. We present a system of partial differential equations for an unknown vector field whose solution would yi

I. Jack, D. R. T. Jones

We present a detailed analysis of how a mixed-anomaly-free U(1) symmetry can be used to both resolve the slepton mass problem associated with Anomaly Mediated Supersymmetry Breaking and generate the fermion mass hierarchy via the Froggatt-Nielsen mechanism. Flavour changing neutral currents problems are evaded by a specific form of the Yukawa textures.

M. Haskins, J. M. Speight

The most fruitful approach to studying low energy soliton dynamics in field theories of Bogomol'nyi type is the geodesic approximation of Manton. In the case of vortices and monopoles, Stuart has obtained rigorous estimates of the errors in this approximation, and hence proved that it is valid in the low speed regime. His method employs energy estimates

F. Bournaud, F. Combes

Polar ring galaxies are peculiar systems in which a gas rich, nearly polar ring surrounds an early-type or elliptical host galaxy. Two formation scenarios for these objects have been proposed: they are thought to form either in major galaxy mergers or by tidal accretion of the polar material from a gas rich donor galaxy. Both scenarios are studied through N-

D. Baskaran, S. R. Lau, A. N. Petrov

For a two-surface B tending to an infinite--radius round sphere at spatial infinity, we consider the Brown--York boundary integral H_B belonging to the energy sector of the gravitational Hamiltonian. Assuming that the lapse function behaves as N \sim 1 in the limit, we find agreement between H_B and the total Arnowitt--Deser--Misner energy, an agreement firs

Claudio D`Antoni, Rainer Verch

The paper "Scaling algebras and short-distance analysis for charge carrying quantum fields" by C. D'Antoni and R. Verch, hep-th/0301145, has been withdrawn by the authors since it was found that it overlaps considerably with independent work contained in the Ph.D.\ thesis by G. Morsella who, at the time when our preprint has been submitted to the

A. Dymarsky, V. Pestun

We consider CIV-DV prepotential F for N=1 SU(n) SYM theory at the extremum of the effective superpotential and prove the relation $2F-S dF/dS = - 2 u_2 Lambda^2n /(n^2-1)$

Anindya Biswas, Sudipta Mukherji, Shesansu Sekhar Pal

We analyse possible cosmological scenarios on a brane where the brane acts as a dynamical boundary of various black holes with anti-de Sitter or de Sitter asymptotics. In many cases, the brane is found to describe completely non-singular universe. In some cases, quantum gravity era of the brane-universe can also be avoided by properly tuning bulk parameters.

Florian Schuetz, Marcus Kollar, Peter Kopietz

We show that at low temperatures T an inhomogeneous radial magnetic field with magnitude B gives rise to a persistent magnetization current around a mesoscopic ferromagnetic Heisenberg ring. Under optimal conditions this spin current can be as large as g mu_B (T / hbar) exp [ - 2 pi (g mu_B B / Delta )^1/2 ], as obtained from leading-order spin-wave theory.

Ezio Vasselli

We construct the crossed product of a C(X)-algebra by an endomorphism, in such a way that the endomorphism itself becomes induced by the bimodule of continuous sections of a vector bundle. Some motivating examples for such a construction are given. Furthermore, we study the C*-algebra of G-invariant elements of the Cuntz-Pimsner algebra associated with a G-v

Y. F. Huang, K. S. Cheng

Gamma-ray burst remnants become trans-relativistic typically in days to tens of days, and they enter the deep Newtonian phase in tens of days to months, during which the majority of shock-accelerated electrons will no longer be highly relativistic. However, a small portion of electrons are still accelerated to ultra-relativistic speeds and capable of emittin

Pierre Mathieu, Elisabeth Remy

We prove that the heat kernel on the infinite Bernoulli percolation cluster in Z^d almost surely decays faster than t^{-d/2}. We also derive estimates on the mixing time for the random walk confined to a finite box. Our approach is based on local isoperimetric inequalities.

Winfried Koller, Alexander Prüll, Hans Gerd Evertz, Wolfgang von der Linden

The ferromagnetic Kondo model with classical corespins is studied via unbiased Monte-Carlo simulations. We show that with realistic parameters for the manganites and at low temperatures, the double-exchange mechanism does not lead to phase separation in one-dimensional chains but rather stabilizes individual ferromagnetic polarons. Within the ferromagnetic p

J. S. Dowker, Klaus Kirsten

Summations and relations involving the Hurwitz and Riemann zeta-functions are extended first to Barnes zeta-functions and then to zeta-functions of general type. The analysis is motivated by the evaluation of determinants on spheres which are treated both by a direct expansion method and by regularised sums. Comments on existing calculations are made. A Kalu

J. -M. Courty, A. Heidmann, M. Pinard

We show that back-action noise in interferometric measurements such as gravitational-waves detectors can be completely suppressed by a local control of mirrors motion. An optomechanical sensor with an optimized measurement strategy is used to monitor mirror displacements. A feedback loop then eliminates radiation-pressure effects without adding noise. This v

Masahiko Higuchi, Hiroshi Yasuhara

An explicitly orbital-dependent correlation energy functional is proposed, which is to be used in combination with the orbital-dependent exchange energy functional in energy-band calculations. It bears a close resemblance to the second-order direct and exchange perturbation terms calculated with Kohn-Sham orbitals and Kohn-Sham energies except that one of th

M. Sami, Pravabati Chingangbam, Tabish Qureshi

We examine the possibility of rolling tachyon to play the dual roll of inflaton at early epochs and dark matter at late times. We argue that enough inflation can be generated with the rolling tachyon either by invoking the large number of branes or brane world assisted inflation. However, reheating is problematic in this model.

Prasanta K. Tripathy, Sandip P. Trivedi

We study compactifications of Type IIB string theory on a K3 \times T^2/Z_2 orientifold in the presence of RR and NS flux. We find the most general supersymmetry preserving, Poincare invariant, vacua in this model. All the complex structure moduli and some of the Kahler moduli are stabilised in these vacua. We obtain in an explicit fashion the restrictions i

Jian Qi Shen

This essay discusses some geometric effects associated with gravitomagnetic fields and gravitomagnetic charge as well as the gravity theory of the latter. Gravitomagnetic charge is the duality of gravitoelectric charge (mass) and is therefore also termed the dual mass which represents the topological property of gravitation. The field equation of gravitomagn

Stephen Montgomery-Smith

We obtain logarithmic improvements for conditions for regularity of the Navier-Stokes equation, similar to those of Prodi-Serrin or Beale-Kato-Majda. Some of the proofs make use of a stochastic approach involving Feynman-Kac like inequalities. As part of the our methods, we give a different approach to a priori estimates of Foias, Guillope and Temam.

Tetsushi Ito

The aim of this paper is to prove the weight-monodromy conjecture (Deligne's conjecture on the purity of monodromy filtration) for varieties p-adically uniformized by the Drinfeld upper half spaces of any dimension. The ingredients of the proof are to prove a special case of the Hodge standard conjecture, and apply a positivity argument of Steenbrink, M.

J. P. Ma

Diffractive photoproduction of $η_c$ is an important process to study the effect of Odderon, whose existence is still not confirmed in experiment. A detailed interpretation of Odderon in QCD, i.e., in terms of gluons is also unclear.Taking charm quarks as heavy quarks, we can use NRQCD and take $η_c$ as a $c\bar c$ bound state. Hence, in the production of $η

Chuan-Hung Chen

We study the nonresonant three-body decays of $B^{+}\to D^{(*)-}_{s} K^{+} π^{+}$ and $B_{d}\to D_{s}^{(*)-} K^{0} π^{+}$. We find that these decays can provide the information on the time-like form factors of $D^{(*)}_{s} K$. We also explicitly investigate $B_{d}\to D_{s}^{(*)-} K^{*+}$ decays by discriminating the nonresonant contributions with the unknown

Vladimir Trifonov

In this note we formalize certain aspects of observation process in an attempt to link the logic of the observer with properties of the observables structures. It is shown that an observer with Boolean logic perceives her environment as a four-dimensional Lorentzian manifold.

X. F. Sun, Seiki Komiya, J. Takeya, Yoichi Ando

Magnetic-field-induced ordering of electrons around vortices is a striking phenomenon recently found in high-$T_c$ cuprates. To identify its consequence in the quasiparticle dynamics, the magnetic-field ($H$) dependence of the low-temperature thermal conductivity $κ$ of La$_{2-x}$Sr$_x$CuO$_4$ crystals is studied for a wide doping range. It is found that the

Michal Horodecki, Aditi Sen De, Ujjwal Sen, Karol Horodecki

We provide a first operational method for checking indistinguishability of orthogonal states by local operations and classical communication (LOCC). This method originates from the one introduced by Ghosh et al. (Phys. Rev. Lett. 87, 5807 (2001) (quant-ph/0106148)), though we deal with pure states. We apply our method to show that an arbitrary complete multi

P. J. Dodd, J. J. Halliwell

Using non-relativistic many body quantum field theory, a master equation is derived for the reduced density matrix of a dilute gas of massive particles undergoing scattering interactions with an environment of light particles. The dynamical variable that naturally decoheres (the pointer basis) is essentially the local number density of the dilute gas. Earlie

E. G. Beltrametti, S. Bugajski

The frame of classical probability theory can be generalized by enlarging the usual family of random variables in order to encompass nondeterministic ones: this leads to a frame in which two kinds of correlations emerge: the classical correlation which is coded in the mixed state of the physical system and a new correlation, to be called probabilistic entang

Arun K. Pati

Quantum operations represented by completely positive maps encompass many of the physical processes and have been very powerful in describing quantum computation and information processing tasks. We introduce the notion of relative phase change for a quantum system undergoing quantum operation. We find that the relative phase shift of a system not only depen

M. A. Martin-Delgado, M. Navascues

We study several properties of distillation protocols to purify multilevel qubit states (qudits) when applied to a certain family of initial mixed bipartite states. We find that it is possible to use qudits states to increase the stability region obtained with the flow equations to distill qubits. In particular, for qutrits we get the phase diagram of the di

David J. Fernandez C

The higher order supersymmetric partners of a stationary periodic potential are studied. The transformation functions associated to the band edges do not change the spectral structure. However, when the transformation is implemented for factorization energies inside of the forbidden bands, the final potential will have again the initial band structure but it

Feng Qi, Zhonghuai Hou, Houwen Xin

In the present letter, we introduce a new method to quantify the effect of disorder on spatiotemporal chaos [Y. Braiman, etc. Nature, 378, p465 (1995)]. Base on the autocorrelation function, we define a parameter to measure the effect of disorder. The results are intriguing and similar to the results obtained by J. Lindner etc. [J. Lindner, etc. Physics Lett

M. A. Batanin

It is well known since Stasheff's work that 1-fold loop spaces can be described in terms of the existence of higher homotopies for associativity (coherence conditions) or equivalently as algebras of contractible non-symmetric operads. The combinatorics of these higher homotopies is well understood and is extremely useful. For $n \ge 2$ the theory of symm

Farzali Izadi

The goal of this paper is to describe all local diffeomorphisms mapping a family of circles, in an open subset of $\r^3$, into straight lines. This paper contains two main results. The first is a complete description of the rectifiable collection of circles in $\r^3$ passing through one point. It turns out that to be rectifiable all circles need to pass thro

Gennaro Amendola

Refining the notion of an ideal triangulation of a compact three-manifold, we provide in this paper a combinatorial presentation of the set of pairs (M,a), where M is a three-manifold and a is a collection of properly embedded arcs. We also show that certain well-understood combinatorial moves are sufficient to relate to each other any two refined triangulat

Nodar Berikashvili

For a fibration with the fiber $K(π,n)$-space, the algebraic model as a twisted tensor product of chains of the base with standard chains of $K(π,n)$-complex is given which preserves multiplicative structure as well. In terms of this model the action of the $n$-cohomology of the base with coefficients in $π$ on the homology of fibration is described.

R. Basili

Given an nxn nilpotent matrix over an algebraically closed field K, we prove some properties of the set of all the nxn nilpotent matrices over K which commute with it. Then we give a proof of the irreducibility of the variety of all the pairs (A,B) of nxn nilpotent matrices over K if either char K = 0 or char K isn't less than n/2. We get as a consequenc

Jan A. Sanders, Jing Ping Wang

In this paper we show that if one writes down the structure equations for the evolution of a curve embedded in an (n)-dimensional Riemannian manifold with constant curvature this leads to a symplectic, a Hamiltonian and an hereditary operator. This gives us a natural connection between finite dimensional geometry, infinite dimensional geometry and integrable

N. Raghavendra

We develop a purely set-theoretic formalism for binary trees and binary graphs. We define a category of binary automata, and display it as a fibred category over the category of binary graphs. We also relate the notion of binary graphs to transition systems, which arise in the theory of concurrent computing.

Igor Rivin

We define a class of multivariate Laurent polynomials closely related to Chebyshev polynomials, and prove the simple but somewhat surprising (in view of the fact that the signs of the coefficients of the Chebyshev polynomials themselves alternate) result that their coefficients are non-negative.

David Ben-Zvi, Edward Frenkel

We apply the technique of localization for vertex algebras to the Segal-Sugawara construction of an ``internal'' action of the Virasoro algebra on affine Kac-Moody algebras. The result is a lifting of twisted differential operators from the moduli of curves to the moduli of curves with bundles, with arbitrary decorations and complex twistings. This c

Yves Le Jan, Olivier Raimond

In this note, it is proved that the noise (in the sense of Tsirelson) generated by a Brownian sticky flow (as defined in math.PR/0211387) is black.

Karen E. Smith

It is proved that tight closure commutes with localization in any domain which has a module finite extension in which tight closure is known to commute with localization. It follows that tight closure commutes with localization in binomial rings, in particular in semigroup or toric rings.

F. Nazarov, M. Sodin, A. Volberg

Consider a class of functions of one real variable with the following uniqueness property: if a function f(x) from the class vanishes on a set of positive measure, then f is the zero function. In many instances, we would like to have a quantitative version of this property, e.g. a lower bound for f(x) outside a small exceptional set. Such estimates are well-

Alon E. Faraggi, Richard S. Garavuso

We demonstrate the existence of a class of N=1 supersymmetric nonperturbative vacua of Horava-Witten M-theory compactified on a torus fibered Calabi-Yau 3-fold Z with first homotopy group π_{1}(Z)= Z2, having the following properties: 1) SO(10) grand unification group, 2) net number of three generations of chiral fermions in the observable sector, and 3) pot

A. Borowiec, M. Ferraris, M. Francaviglia

Chern--Simons type Lagrangians in $d=3$ dimensions are analyzed from the point of view of their covariance and globality. We use the transgression formula to find out a new fully covariant and global Lagrangian for Chern--Simons gravity: the price for establishing globality is hidden in a bimetric (or biconnection) structure. Such a formulation allows to cal

Chanju Kim, Hang Bae Kim, Yoonbai Kim, O-Kab Kwon

We study dynamics of rolling tachyon and Abelian gauge field on unstable D-branes, of which effective action is given by Born-Infeld type nonlocal action. Possible cosmological evolutions are also discussed. In the Einstein frame of string cosmology, every expanding flat universe is proven to be decelerating.

George E. A. Matsas, Daniel A. T. Vanzella

We investigate the weak-interaction emission of spin-1/2 fermions from decaying (and non-decaying) particles endowed with uniform circular motion. The decay of swirling protons and the neutrino- antineutrino emission from circularly moving electrons are analyzed in some detail. The relevance of our results to astrophysics is commented.

C. Armendariz-Picon, Patrick B. Greene

We consider toy cosmological models in which a classical, homogeneous, spinor field provides a dominant or sub-dominant contribution to the energy-momentum tensor of a flat Friedmann-Robertson-Walker universe. We find that, if such a field were to exist, appropriate choices of the spinor self-interaction would generate a rich variety of behaviors, quite diff

P. Salmi, R. Kinnunen, N. Stepanov

The possibility to detect the massive charged Higgs boson H using the hadronic decay channel H -> tb in the associated production pp -> tH + X in the CMS experiment at LHC is studied. There is a large background from ttbb events which makes the observation difficult. Detection of a Higgs signal in this channel requires an excellent b-tagging performance. Goo

T. Csorgo

Theoretical results in the tau-model are discussed in the context of Bose-Einstein correlations in e+e- annihilations at LEP1 and LEP2 as well as that of relativistic heavy ion collisions at SPS and RHIC.

Roberto Casalbuoni

We discuss the possibility that in finite density QCD an anisotropic phase is realized. This case might arise for quarks with different chemical potential and/or different masses. In this phase crystalline structures may be formed. We consider this possibility and we describe, in the context of an effective lagrangian, the corresponding phonons as the Nambu-

Wojciech Krolikowski

We suggest that the Large Mixing Angle MSW solar solution, whose unique physical status is confidently supported by the recent results from KamLAND experiments, gets its justification in the fermion universality, interpreted for neutrinos and charged leptons in a straightforward way, most readily in the framework of seesaw mechanism. To this end, we consider

T. N. Pham

The recent Belle and Babar measurements of the branching ratios $B^- \to π^+ π^- K^-$ and $B^- \to K^+ K^- K^-$ and $B^\pm \to χ_{c0} K^\pm$ have renewed interests in these decays as another mean to look for direct CP violation in B decays. In this talk, I would like to discuss a recent analysis of the CP violating asymmetry in the partial widths for the dec

Gino Isidori

After a brief introduction to the so-called flavour problem, we discuss the role of rare K decays in probing the mechanism of quark-flavour mixing. Particular attention is devoted to the formulation of the Minimal Flavour Violation hypothesis, as a general and natural solution to the flavour problem, and to the fundamental role of K -> pi nu nu-bar decays in

A. Jakovac

Because of IR (pinch) singularities a resummation is necessary in non-equilibrium field theories, that can be performed by using Kadanoff--Baym equations. Taking Landau prescription correctly into account, Kadanoff--Baym equations reduce to Boltzmann equations only in a restricted kinematical range; in other cases a new equation (the former constraint equati

A. Ringwald

A measurement of the big bang relic neutrinos would open a new window to the early universe. We review various possibilities to detect this cosmic neutrino background and substantiate the assertion that -- apart from the rather indirect evidence to be gained from cosmology and large-scale structure formation -- the annihilation of ultrahigh energy cosmic neu

M. Kuroda, D. Schildknecht

We examine the total cross section of virtual photons on protons, $σ_{γ^* p}(W^2,Q^2)$, at low $x \cong Q^2/W^2 \ll 1$ and its connection with ``elastic'' diffractive production $γ^*_{T,L}p \to X^{J=1}_{T,L} p$ in the two-gluon exchange dynamics for the virtual forward Compton scattering amplitude. Solely based on the generic structure of two-gluon e

W. J. Huo, T. F. Feng

We investigate the lepton flavor violation (LFV) decays, $τ\to lγ$ ($l=μ, e$) and $μ\to eγ$, and the newly observed muon $g-2$ anomaly in the framwork of a squential fourth generation model with a heavy fourth neutrino, $ν'$. By using the recent experimental bounds, we take the constraints of the $4\times 4$ leptonic mixing matrix element factors, $|V_{1

Anatoly Kopylov, Valery Petukhov

We show that a lithium experiment has a potential to confirm or reject the value 1.5% of the solar luminosity attributed to a CNO-cycle by the SSM and to prove that the difference between total energy release of the Sun and what is produced in a hydrogen sequence is really produced in CNO cycle. This will be the stringent test of the theory of stellar evolut

H1 Collaboration

A search for events with a high energy isolated electron or muon and missing transverse momentum has been performed at the electron-proton collider HERA using an integrated luminosity of 13.6 pb-1 in e-p scattering and 104.7 pb-1 in e+p scattering. Within the Standard Model such events are expected to be mainly due to W boson production with subsequent lepto

G. E. Romero

The Kalam Cosmological Argument is perhaps the most solid and widly discussed argument for a caused creation of the universe. The usual objections to the argument mainly focus on the second premise. In this paper we discuss the dependency of the first premise on the topological structure of the space-time manifold adopted for the underlying cosmological mode

Millist W. Vincent, Jixue Liu

XML is of great importance in information storage and retrieval because of its recent emergence as a standard for data representation and interchange on the Internet. However XML provides little semantic content and as a result several papers have addressed the topic of how to improve the semantic expressiveness of XML. Among the most important of these appr

E. Paladino, F. Taddei, G. Giaquinta, G. Falci

We derive the effective hamiltonian for a charge-Josephson qubit in a circuit with no use of phenomenological arguments, showing how energy renormalizations induced by the environment appear with no need of phenomenological counterterms. This analysis may be important for multiqubit systems and geometric quantum computation.

M. Mercedes Calbi, Silvina M. Gatica, Milton W. Cole

We evaluate the equation of state of the quasi-one-dimensional (1D) phase of C60 molecules in small carbon nanotubes, nicknamed ``peas in a pod''. The chemical potential and 1D pressure are evaluated as functions of the temperature and density, initially with the approximation of nearest neighbor interactions and classical statistical mechanics. Quan

V. S. Khrapai, A. A. Shashkin, V. T. Dolgopolov

Using magnetocapacitance data in tilted magnetic fields, we directly determine the chemical potential jump in a strongly correlated two-dimensional electron system in silicon when the filling factor traverses the spin and the cyclotron gaps. The data yield an effective g-factor that is close to its value in bulk silicon and does not depend on filling factor.

M. Johnsson, K. W. Toernroos, P. Lemmens, P. Millet

Two new transition-metal tellurium oxy-chlorides of the general formula Ni_5(TeO_3)_4X_2 (X=Cl, Br) have been isolated during the investigation of the ternary phase diagram NiO-NiCl2-TeO2. They crystallize in the monoclinic system, space group C2/c, and for the case of Ni_5(TeO_3)_4Cl_2 the unit cell is a=19.5674(2) A, b=5.2457(1) A, c=16.3084(1) A, with bet

Krzysztof Rogacki

In this article, we examine the superconducting properties of low- and high-$T_c$ magnetic superconductors in magnetic fields close to the first penetration field. Attention is paid to the properties that relate to the interactions between antiferromagnetism and superconductivity. It is suggested that several features characterizing the interplay between mag

C. Fusco, A. Fasolino, T. Janssen

We study the dynamics of a dimer moving on a periodic one-dimensional substrate as a function of the initial kinetic energy at zero temperature. The aim is to describe, in a simplified picture, the microscopic dynamics of diatomic molecules on periodic surfaces, which is of importance for thin film formation and crystal growth. We find a complex behaviour, c

D. A. Abanin

It is shown that surface of a liquid consisting of several interpenetrating superfluids becomes unstable at some threshold. We demonstrate that the criterion for the onset of the instability changes in the presence of dissipative interaction between the surface and the environment. Possible physical applications of the surface instability are discussed.

Jonathan P. K. Doye, David J. Wales

Recently, the properties of supercooled liquids have been studied by mapping instaneous configurations onto minima of the gradient squared. It was originally suggested that this mapping would probe higher-order saddle points of the potential energy surface. However, it was subsequently shown that the majority of the minima of this function are only local min

Christian Beck

We consider a generalized statistical mechanics model for the creation process of cosmic rays which takes into account local temperature fluctuations. This model yields Tsallis statistics for the cosmic ray spectrum. It predicts an entropic index q given by q=11/9 at largest energies (equivalent to a spectral index of alpha=5/2), and an effective temperature

A. Rosa, D. Marenduzzo, A. Maritan, F. Seno

We study the thermodynamics of an exactly solvable model of a self-interacting partially directed self-avoiding walk (DSAW) in two dimensions, when a force is applied on one end of the chain. The critical force for the unfolding is determined exactly, as a function of the temperature, below the $Θ$-transition. The transition is second order and characterized

Cheng-shi Liu, Ben-kun Ma

Using the three-site Hubbard model and Floquet theorem, we investigate the dynamical behaviors of two electrons which are confined in a line-shape three quantum dot molecule driven by an AC electric field. Because the Hamiltonian contains no spin-flip terms, the six- dimension singlet state and nine-dimensional triplet state sub-spaces are decoupled and can

Matthias Paessens

We compare the Rubinstein-Duke model for reptation to a model where the boundary dynamics is modified by calculating the viscosity of polymer melts. The question is investigated whether the viscosity is determined by details of the dynamics of the polymer ends or by the stretching of the polymer. To this end the dependence of the viscosity on the particle de

R. D. Willmann, G. M. Schütz, K. Jain

Using a generalized Rubinstein-Duke model we prove rigorously that kinematic disorder leaves the prediction of standard reptation theory for the scaling of the diffusion constant in the limit for long polymer chains $D \propto L^{-2}$ unaffected. Based on an analytical calculation as well as Monte Carlo simulations we predict kinematic disorder to affect the

M. A. Korotin, N. A. Skorikov, V. I. Anisimov

The electronic structure of the vanadium dioxide VO_2 in the tetragonal R and two monocinic M_1 and M_2 structural modifications was calculated in frames of the local-density functional (LDA) approach and the LSDA + U formalism of correction for correlation effects. Based on the results of calculation, we argue in favor of the Mott-Hubbard mechanism of the m

J. Dzubiella, C. N. Likos

We examine the out-of-equilibrium dynamical evolution of density profiles of ultrasoft particles under time-varying external confining potentials in three spatial dimensions. The theoretical formalism employed is the dynamical density functional theory (DDFT) of Marini Bettolo Marconi and Tarazona [J. Chem. Phys. {\bf 110}, 8032 (1999)], supplied by an equil

Petr Jizba

We present a discussion of generalized statistics based on Renyi's, Fisher's and Tsallis's measures of information. The unifying conceptual framework which we employ here is provided by information theory. Important applications of generalized statistics to systems with (multi-)fractal structure are examined.

Leonid D. Son, German M. Rusakov, Alexander Z. Patashinski, Mark A. Ratner

A coarsened model for a binary system with limited miscibility of components is proposed; the system is described in terms of structural states in small parts of the material. The material is assumed to have two alternative types of crystalline local arrangements associated with two components of the alloy. Fluctuating characteristics of a cluster are the ty

Kenneth G. Libbrecht

We propose a new type of morphological instability in the diffusion-limited growth of faceted crystals from the vapor phase that can explain the formation of thin ice plates at temperatures near -15 C. The instability appears when the attachment kinetics for facet growth depends strongly on the morphology of the facet surface. In particular, we propose that

Michio Watanabe, David B. Haviland

We review experiments on small-capacitance Josephson junctions. When the Josephson junction is fabricated in the configuration of dc superconducting quantum interference device (SQUID), the Josephson coupling can be tuned IN SITU with an external magnetic field. The electrical transport properties of one-dimensional arrays of small-capacitance dc SQUIDs have

D. -N. Peligrad, B. Nebendahl, M. Mehring, A. Dulcic

Critical fluctuations above $T_c$ are studied in the microwave complex conductivity of BSCCO-2212, BSCCO-2223, and YBCO thin films. The analysis of the experimental data yields the temperature dependences of the reduced coherence length $ξ(T)/ξ_0$. Two critical regimes are observed, having the static critical exponent $ν=1$ close to $T_c$, and a crosover to

Z. Ivezic, R. H. Lupton, S. Anderson, L. Eyer

The potential of the Sloan Digital Sky Survey for wide-field variability studies is illustrated using multi-epoch observations for 3,000,000 point sources observed in 700 deg2 of sky, with time spans ranging from 3 hours to 3 years. These repeated observations of the same sources demonstrate that SDSS delivers ~0.02 mag photometry with well behaved and under

C. Charmousis, V. Onemli, Z. Qiu, P. Sikivie

Dark matter caustics have specific density profiles and, therefore, precisely calculable gravitational lensing properties. We present a formalism which simplifies the relevant calculations, and apply it to four specific cases. In the first three, the line of sight is tangent to a smooth caustic surface. The curvature of the surface at the tangent point is po

Asantha R. Cooray, J. L. Elliot

We revisit the GSC5249-01240 light curve obtained during its occultation by Saturn's North polar region. In addition to refractive scintillations, the power spectrum of intensity fluctuations shows an enhancement of power between refractive and diffractive regimes. We identify this excess power as due to high amplitude spikes in the light curve and sugge

Kristen Menou

Idealized models are used to illustrate the potential of the Laser Interferometer Space Antenna (LISA) as a probe of the largely unknown population of cosmologically-distant Massive Black Holes (MBHs) and as a tool to measure their masses with unprecedented accuracy. The models suggest that LISA will most efficiently probe a MBH population of lower mass than

S. A. Sim, C. Jordan

Analyses of the widths and shifts of optically thin emission lines in the ultraviolet spectrum of the active dwarf Epsilon Eri (K2 V) are presented. The spectra were obtained using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer. The line widths are used to find the non-thermal energy dens

Steven Gratton, Justin Khoury, Paul J. Steinhardt, Neil Turok

We analyze the general conditions on the equation of state $w$ required for quantum fluctuations of a scalar field to produce a scale-invariant spectrum of density perturbations, including models which (in the four dimensional effective description) bounce from a contracting to an expanding phase. We show that there are only two robust cases: $w\approx -1$ (

Nathan Smith, Kris Davidson, Theodore R. Gull, Kazunori Ishibashi

The Homunculus reflection nebula around eta Carinae provides a rare opportunity to observe the spectrum of a star from multiple latitudes. We present STIS spectra of several positions in the Homunculus, showing directly that eta Car has an aspherical stellar wind. P Cygni absorption in Balmer lines depends on latitude, with high velocities and strong absorpt

Krzysztof Gesicki, Agnes Acker, Albert A. Zijlstra

This paper discusses the location of a sample of planetary nebulae on the HR diagram. We determine the internal velocity fields of 14 planetary nebulae from high-resolution echelle spectroscopy, with the help of photoionization models. The mass averaged velocity is shown to be a robust, simple parameter describing the outflow. The expansion velocity and radi

G. Ghirlanda, A. Celotti, G. Ghisellini

We consider the evidence for very hard low energy spectra during the prompt phase of Gamma Ray Bursts (GRB). In particular we examine the spectral evolution of GRB 980306 together with the detailed analysis of some other bursts already presented in the literature (GRB 911118, GRB 910807, GRB 910927 and GRB 970111), and check for the significance of their har

Arnon Dar

The cannonball model (CB) of gamma ray bursts (GRBs) is incredibly more successful than the standard blast-wave models (SM) of GRBs, which suffer from profound inadequacies and limited predictive power. The CB model is falsifiable in its hypothesis and results. Its predictions are summarized in simple analytical expressions, derived, in fair approximations,

M. Castellani, G. Bono, R. Buonanno, F. Caputo

We present B, V photometric data of the Carina Dwarf Spheroidal Galaxy collected with the Wide Field Imager (WFI) available at the 2.2m MPI/ESO telescope. We briefly discuss the main features of the color magnitude diagram and in particular the mix of stellar populations present in this galaxy. A preliminary analysis of the spatial distribution of these popu

S. Bianchi, J. Goncalves, M. Albrecht, P. Caselli

We have observed the dark cloud Barnard 68 with SCUBA at 850 um and with SIMBA at 1.2 mm. The submillimetre and millimetre dust emission correlate well with the extinction map of Alves, Lada and Lada (2001).The A_V/850um correlation is clearly not linear and suggests lower temperatures for the dust in the inner core of the cloud. Assuming a model for the tem

Andreas Burkert, Thorsten Naab

The formation of elliptical galaxies as a result of the merging of spiral galaxies is discussed. We analyse a large set of numerical N-Body merger simulations which show that major mergers can in principle explain the observed isophotal fine structure of ellipticals and its correlation with kinematical properties. Equal-mass mergers lead to boxy, slowly rota

Boris E. Stern

It is shown that an ultrarelativistic shock with the Lorentz factor of order of tens or higher propagating in a moderately dense interstellar medium (density above $\sim 1000 $ cm$^{-3}$) undergoes a fast dramatic transformation into a highly radiative state. The process leading to this phenomenon resembles the first order Fermi acceleration with the differe

Chris Done, Greg M. Madejski, Piotr T. Zycki, Lincoln J. Greenhill

We analyze recent simultaneous Chandra/RXTE observations of the Seyfert 2 galaxy NGC 4945. The unprecedented spatial resolution of Chandra means we are able to separate the spectra of the nucleus, starburst and superwind regions, while the RXTE data extend the spectrum to higher energies. The extreme absorbing column of $N_H\sim 4\times 10^{24}$ cm$^{-2}$ me

S. Johansson, U. Litzén, H. Lundberg, Z. Zhang

We have measured the oscillator strength of the Ni I line at 6300.34 Å, which is known to be blended with the forbidden [O I] $λ$6300 line, used for determination of the oxygen abundance in cool stars. We give also wavelengths of the two isotopic line components of $^{58}$Ni and $^{60}$Ni derived from the asymmetric laboratory line profile. These two line co