January 2004 arXiv papers — page 18

Giulio Biroli, Jean-Philippe Bouchaud

We show that the glass transition predicted by the Mode-Coupling Theory (MCT) is a critical phenomenon with a diverging length and time scale associated to the cooperativity of the dynamics. We obtain the scaling exponents nu and z that relate space and time scales to the distance from criticality, as well as the scaling form of the critical four-point corre

Marek Szydlowski, Adam Krawiec, Wojciech Czaja

We study the Friedmann-Robertson-Walker model with phantom fields modelled in terms of scalar fields. We apply the Ziglin theory of integrability and find that the flat model is nonintegrable. Then we cannot expect to determine simple analytical solutions of the Einstein equations. We demonstrate that there is only a discrete set of parameters where this mod

A. Peles, B. W. Southern, B. Delamotte, D. Mouhanna

Monte Carlo methods are used to study a family of three dimensional XY frustrated models interpolating continuously between the stacked triangular antiferromagnets and a variant of this model for which a local rigidity constraint is imposed. Our study leads us to conclude that generically weak first order behavior occurs in this family of models in agreement

S. Serjeant, A. Carraminana, E. Gonzales-Solares, P. Heraudeau

We present the 90 micron luminosity function of the Final Analysis of the European Large Area ISO Survey (ELAIS), extending the sample size of our previous analysis (paper IV) by about a factor of 4. Our sample extends to z=1.1, around 50 times the comoving volume of paper IV, and 10^{7.7} < h^{-2}L/Lsun < 10^{12.5}. From our optical spectroscopy campaigns o

Kazuhiro Sano, Yoshiaki Ono

The one-dimensional extended Hubbard model with both the on-site $U$ and the nearest neighbor $V$ interactions at quarter filling is studied by using a novel finite size scaling. We diagonalize finite size systems numerically and calculate the Luttinger-liquid parameter $K_ρ$ which is substituted into the renormalization group equation as an initial conditio

Chun-Khiang Chua, George W. S. Hou, Shiue-Yuan Shiau, Shang-Yuu Tsai

Motivated by experimental results on $\bar B\to D^{(*)}K^-K^{0}$, we use a factorization approach to study these decays. Two mechanisms concerning kaon pair production arise: current-produced (from vacuum) and transition (from the $B$ meson). The kaon pair in the $\bar B {}^0\to D^{(*)+}K^-K^0$ decays can be produced only by the vector current (current-produ

Girma Hailu, Howard Georgi

We discuss exact results for the full nonperturbative effective superpotentials of four dimensional $\mathcal{N}=1$ supersymmetric U(N) gauge theories with additional chiral superfield in the adjoint representation and the free energies of the related zero dimensional bosonic matrix models with polynomial potentials in the planar limit using the Dijkgraaf-Va

Barak Dayan, Avi Pe&#39;er, Asher A. Friesem, Yaron Silberberg

We experimentally demonstrate two-photon absorption (TPA) with broadband down-converted light (squeezed vacuum). Although incoherent and exhibiting the statistics of a thermal noise, broadband down-converted light can induce TPA with the same sharp temporal behavior as femtosecond pulses, while exhibiting the high spectral resolution of the narrowband pump l

M. Lorente

The Kravchuk and Meixner polynomials of discrete variable are introduced for the discrete models of the harmonic oscillator and hydrogen atom. Starting from Rodrigues formula we construct raising and lowering operators, commutation and anticommutation relations. The physical properties of discrete models are figured out through the equivalence with the conti

Tamas Geszti

Within Newton-Schrödinger quantum mechanics which allows gravitational self-interaction, it is shown that a no-split no-collapse measurement scenario is possible. A macroscopic pointer moves at low acceleration, controlled by the Ehrenfest-averaged force acting on it. That makes classicality self-sustaining, resolves Everett&#39;s paradox, and outlines a way

H. L. Harney, W. D. Heiss

Eigenvectors of decaying quantum systems are studied at exceptional points of the Hamiltonian. Special attention is paid to the properties of the system under time reversal symmetry breaking. At the exceptional point the chiral character of the system -- found for time reversal symmetry -- generically persists. It is, however, no longer circular but rather e

D. Daems, S. Guérin, H. R. Jauslin, A. Keller

We review various unitary time-dependent perturbation theories and compare them formally and numerically. We show that the Kolmogorov-Arnold-Moser technique performs better owing to both the superexponential character of correction terms and the possibility to optimize the accuracy of a given level of approximation which is explored in details here. As an il

D. Sugny, A. Keller, O. Atabek, D. Daems

We present a strategy for post-pulse orientation aiming both at efficiency and maximal duration within a rotational period. We first identify the optimally oriented states which fulfill both requirements. We show that a sequence of half-cycle pulses of moderate intensity can be devised for reaching these target states.

V. F. Morozov, Shura Hayryan, E. Sh. Mamasakhlisov, A. V. Grigoryan

A simplified model for the closed circular DNA (ccDNA) is proposed to describe some specific features of the helix-coil transition in such molecule. The Hamiltonian of ccDNA is related to the one introduced earlier for the linear DNA. The basic assumption is that the reduced energy of the hydrogen bond is not constant through the transition process but depen

R. J. Taft, J. S. Mattick

Background: Prior to the current genomic era it was suggested that the number of protein-coding genes that an organism made use of was a valid measure of its complexity. It is now clear, however, that major incongruities exist and that there is only a weak relationship between biological complexity and the number of protein coding genes. For example, using t

V. V. Mekhonoshin, Adrian Lange

The linear stability analysis of the Faraday instability on a viscous ferrofluid in a horizontal magnetic field is performed. Strong dipole-dipole interactions lead to the formation of chains elongated in the field direction. The formation of chains results in a qualitative new behaviour of the ferrofluid. This new behaviour is characterized by a neutral sta

A. Baldini, C. Bemporad, F. Cei, T. Doke

The optical properties of LXe in the vacuum ultra violet (VUV), determining the performance of a scintillation calorimeter, are discussed in detail. The available data, measured in a wider spectral region from visible to UV light, and in a large range of Xe densities, from gas to liquid, are examined. It is shown that this information can be used for derivin

Robert A. Crowell, Rui Lian, Ilya A. Shkrob, David M. Bartels

Charge-transfer-to-solvent (CTTS) reactions of hydroxide induced by 200 nm monophotonic or 337 nm and 389 nm biphotonic excitation of this anion in aqueous solution have been studied by means of pump-probe ultrafast laser spectroscopy. Transient absorption kinetics of the hydrated electron, eaq-, have been observed, from a few hundred femtoseconds out to 600

J. Dobaczewski, N. Michel, W. Nazarewicz, M. Ploszajczak

The progress in the modeling of exotic nuclei with an extreme neutron-to-proton ratio is discussed. Two topics are emphasized: (i) the quest for the universal microscopic nuclear energy density functional and (ii) the progress in the continuum shell model.

D. N. Kadrev, M. V. Ivanov, A. N. Antonov, C. Giusti

Using the relationship between the two-particle overlap functions (TOF&#39;s) and the two-body density matrix (TDM), the TOF&#39;s for $^{16}$O$(e,e^{\prime}pp)^{14}$C reaction are calculated on the basis of TDM obtained with a Jastrow-type approach. The main contributions of the removal of $^1S$ and $^3P$ $pp$-pairs from $^{16}$O are taken into account in t

C. Pruneau

We present measurements of net charge and transverse momentum fluctuations in Au + Au collisions at ?sNN = 20, 130, and 200 GeV reported in our QM 2004 poster using measures ?+-,dyn and <?pt,1 ?pt,2>. We observe the dynamical fluctuations are finite at all three energies and exhibit a rather modest dependence on beam energy. We also find both net charge and

S. Baskal, Y. S. Kim

It is possible to associate two angles with two successive non-collinear Lorentz boosts. If one boost is applied after the initial boost, the result is the final boost preceded by a rotation called the Wigner rotation. The other rotation is associated with Wigner&#39;s O(3)-like little group. These two angles are shown to be different. However, it is shown t

Alan Carey, Hendrik Grundling

Let G be one of the local gauge groups C(X,U(n)), C^\infty(X,U(n)), C(X,SU(n)) or C^\infty(X,SU(n)) where X is a compact Riemannian manifold. We observe that G has a nontrivial group topology, coarser than its natural topology, w.r.t. which it is amenable, viz the relative weak topology of C(X,M(n)). This topology seems more useful than other known amenable

John Gough

We construct a transformation between Bose Fock space and Fermi Fock space that is super-symmetric in the sense that it converts Boson fields into Fermi fields over a fixed one-particle space. The transformation involves the spectral splitting of the one-particle space into a continuous direct integral of internal spaces. We present a theory of integration o

Martin Hildebrand

A number of papers have examined various aspects of &#34;random random&#34; walks on finite groups; the purpose of this article is to provide a survey of this work and to show, bring together, and discuss some of the arguments and results in this work. This article also provides a number of exercises. Some exercises involve straightforward computations; othe

R. H. Levene, S. C. Power

The hyperbolic algebra A_h, studied recently by Katavolos and Power, is the weak star closed operator algebra on L^2(R) generated by H^\infty(R), as multiplication operators, and by the dilation operators V_t, t \geq 0, given by V_t f(x) = e^{t/2} f(e^t x). We show that A_h is a reflexive operator algebra and that the four dimensional manifold Lat A_h (with

Gabriela Schmithuesen

We study the Veech group of an origami, i.e. of a translation surface, tessellated by parallelograms. We show that it is isomorphic to the image of a certain subgroup of Aut(F_2) in SL_2(Z) = Out^+(F_2). Based on this we present an algorithm that determines the Veech group.

J. Scott Carter, Masahico Saito

This paper is a brief overview of some of our recent results in collaboration with other authors. The cocycle invariants of classical knots and knotted surfaces are summarized, and some applications are presented.

Alireza Sarveniazi

In this paper I study Ramanujan hypergraps and both abstract and explicit constructions is given.

C. A. Rossi

The motivation for this paper stems \cite{CR} from the need to construct explicit isomorphisms of (possibly nontrivial) principal $G$-bundles on the space of loops or, more generally, of paths in some manifold $M$, over which I consider a fixed principal bundle $P$; the aforementioned bundles are then pull-backs of $P$ w.r.t. evaluation maps at different poi

William P. Orrick

We study the question of finding the maximal determinant of matrices of odd order with entries {-1,1}. The most general upper bound on the maximal determinant, due to Barba, can only be achieved when the order is the sum of two consecutive squares. It is conjectured that the bound is always attained in such cases. Apart from these, only in orders 3, 7, 9, 11

Gregory Lupton, Samuel Bruce Smith

Let w: Map(X,Y;f) -> Y denote a general evaluation fibration. Working in the setting of rational homotopy theory via differential graded Lie algebras, we identify the long exact sequence induced on rational homotopy groups by w in terms of (generalized) derivation spaces and adjoint maps. As a consequence, we obtain a unified description of the rational homo

Lars Eldén

The Google matrix is a positive, column-stochastic matrix that is used to compute the pagerank of all the web pages on the Internet: the eigenvector corresponding to the eigenvalue 1 is the pagerank vector. Due to its huge dimension, of the order of billions, the (presently) only viable method to compute the eigenvector is the power method. For the convergen

Michael Joswig

This is a survey of known algorithms in algebraic topology with a focus on finite simplicial complexes and, in particular, simplicial manifolds. Wherever possible an elementary approach is chosen. This way the text may also serve as a condensed but very basic introduction to the algebraic topology of simplicial manifolds. This text will appear as a chapter i

Nicholas Eriksson

We consider the phylogenetic tree model in which every node of the tree is observed and binary and the transitions are given by the same matrix on each edge of the tree. We are able to compute the Grobner basis and Markov basis of the toric ideal of invariants for trees with up to 11 nodes. These are perhaps the first non-trivial Grobner bases calculations i

Jean-Baptiste Butruille

We prove Gray & Wolf&#39;s conjecture that a Riemannian homogeneous manifold admitting a strict nearly Kahler structure is 3-symmetric. We actually classify them in dimension 6 and use previous results of Swann, Cleyton and Nagy to prove the conjecture in higher dimensions.

Kalle Karu

We generalize the toric residue mirror conjecture of Batyrev and Materov to not necessarily reflexive polytopes. Using this generalization we prove the toric residue mirror conjecture for Calabi-Yau complete intersections in Gorenstein toric Fano varieties.

Andrea Posilicano

Given the symmetric operator $A_N$ obtained by restricting the self-adjoint operator $A$ to $N$, a linear dense set, closed with respect to the graph norm, we determine a convenient boundary triple for the adjoint $A_N^*$ and the corresponding Weyl function. These objects provide us with the self-adjoint extensions of $A_N$ and their resolvents.

Denis Kochan, Pavol Severa

We study &#34;higher-dimensional&#34; generalizations of differential forms. Just as differential forms can be defined as the universal commutative differential algebra containing C^\infty(M), we can define differential gorms as the universal commutative bidifferential algebra. From a more conceptual point of view, differential forms are functions on the sup

E. Frenkel, D. Gaitsgory

Let ${\mathfrak g}$ be a simple Lie algebra. For a level $κ$ (thought of as a symmetric ${\mathfrak g}$-invariant form of ${\mathfrak g}$), let $\hat{\mathfrak g}_κ$ be the corresponding affine Kac-Moody algebra. Let $Gr_G$ be the affine Grassmannian of ${\mathfrak g}$, and let $D_κ(Gr_G)-mod$ be the category of $κ$-twisted right D-modules on $Gr_G$. By taki

David Kerr

We consider the topological entropy of state space and quasi-state space homeomorphisms induced from C*-algebra automorphisms. Our main result asserts that, for automorphisms of separable exact C*-algebras, zero Voiculescu-Brown entropy implies zero topological entropy on the quasi-state space (and also more generally on the entire unit ball of the dual). As

Gady Kozma, Ehud Schreiber

We give two algorithms that allow to get arbitrary precision asymptotics for the harmonic potential of a random walk.

S. G. Naculich, H. J. Schnitzer, N. Wyllard

We describe how the ingredients and results of the Seiberg-Witten solution to N=2 supersymmetric U(N) gauge theory may be obtained from a matrix model.

Pio J. Arias, Rolando Gaitan D.

Lagrangian constraints of the spin 2 selfdual theory in a 2+1 flat space-time are studied and the one degree of freedom reduced action is obtained. From this formulation, the quantum operator algebra is computed and the spin contribution on transformation generators is explored.

Oren Bergman

In certain backgrounds string theory exhibits quantum Hall-like behavior. These backgrounds provide an explicit realization of the effective non-commutative gauge theory description of the fractional quantum Hall effect (FQHE), and of the corresponding large N matrix model. I review results on the string theory realization of the two-dimensional fractional q

Yi Liao, Klaus Sibold

We point out that a field ϕcharged under a global U(1) symmetry generally allows for a starred localized extension with the transformation rule, ϕ\to U_L\starϕ\star U_R^{-1}. This results in a double gauging of the global U(1) symmetry on noncommutative space. We interpret the gauge theory so obtained in terms of the gauge fields that in the commutative limi

Pio J. Arias

It is shown that the non-abelian vectorial model, proposed by C.R.Hagen is obtained using the self-interaction mechanism. The equivalence between this model and the non-abelian topologically massive one is studied showing that the existing equivalence between the abelian models is not sustained.

Maja Buric, Voja Radovanovic

We analyze the divergent part of the one-loop effective action for the noncommutative SU(2) gauge theory coupled to the fermions in the fundamental representation. We show that the divergencies in the 2-point and the 3-point functions in the $θ$-linear order can be renormalized, while the divergence in the 4-point fermionic function cannot.

Masato Arai, Muneto Nitta, Norisuke Sakai

With the non-Abelian Hyper-Kahler quotient by U(M) and SU(M) gauge groups, we give the massive Hyper-Kahler sigma models that are not toric in the N=1 superfield formalism. The U(M) quotient gives N!/[M! (N-M)!] (N is a number of flavors) discrete vacua that may allow various types of domain walls, whereas the SU(M) quotient gives no discrete vacua. We deriv

Rong-Gen Cai

The Lovelock gravity consists of the dimensionally extended Euler densities. The geometry and horizon structure of black hole solutions could be quite complicated in this gravity, however, we find that some thermodynamic quantities of the black holes like the mass, Hawking temperature and entropy, have simple forms expressed in terms of horizon radius. The c

Thomas Appelquist, Maurizio Piai, Robert Shrock

We analyze the diagonal and transition magnetic and electric dipole moments of charged leptons in extended technicolor (ETC) models, taking account of the multiscale nature of the ETC gauge symmetry breaking, conformal (walking) behavior of the technicolor theory, and mixing in the charged-lepton mass matrix. We show that mixing effects dominate the ETC cont

T. Shishkina

The main possibilities of investigation of leptons and bosons birth in interaction of polarized photons are considered. The usage of $γγ\to f \bar{f} [+γ]$ reactions for the luminosity measurement on linear photon collider is analyzed. The achievable precision of the luminosity measuring is considered and calculated. The first-order QED correction to $γγ\to

Mauro Moretti

The strategies recently developed to study Higgs boson properties at the LHC are reviewed. It is shown how to obtain model-independent determinations of couplings to fermions and gauge bosons by exploiting different production and decay channels. We consider the case of Weak Boson Fusion Higgs production with H decaying into b anti-b

C. Diaconu

The production of isolated leptons with high transverse momentum in high energy e-e, p-p or e-p collisions is reviewed. The leptons are produced either through boson splitting or by boson-boson collision and yield experimentally simple and spectacular topologies which can be exploited to validate the Standard Model or to search for new phenomena.

Radovan Dermisek

We show that gauge couplings unify more precisely in the region of SUSY parameter space already preferred by Yukawa unification. While proton decay due to dimension 5 operators is maximally suppressed in this region, the contribution from dimension 6 operators is enhanced as a consequence of lower unification scale.

Hongya Liu

Exact Newtonian potential with an extra space dimension compactified on a circle is derived and studied. It is found that a point mass located at one side of the circle can generate almost the same strength of gravitational force at the other side. Combined with the brane-world scenarios, it means that although one can not see a particle which is confined to

Z. Fodor, S. D. Katz

We present results on lattice QCD at finite temperature (T) and chemical potential (μ). We apply the overlap-improving multi-parameter reweighting technique for n_f=4 and 2+1 staggered QCD. We use semi-realistic masses on L_t=4 lattices. The critical endpoint (E) of 2+1 flavour QCD on the μ-T plane is located. Our results are based on {\cal{O}}(10^3-10^4) co

F. Csikor, G. I. Egri, Z. Fodor, S. D. Katz

We present N_t=4 lattice results for the equation of state of 2+1 flavour staggered, dynamical QCD at finite temperature and chemical potential. We use the overlap improving multi-parameter reweighting technique to extend the equation of state for non-vanishing chemical potentials. The results are obtained along the line of constant physics. Our physical par

Giuseppe Latino

An overview of Run I jet physics at the ppbar Fermilab Tevatron Collider with a particular emphasis on inclusive jet cross section measurements is given. The impact of these studies on PDFs constrain from global fits is underlined. Preliminary results on inclusive jet and di-jet mass cross section measurements in Run II are then summarized.

Alan Barnes

Spacetimes in which the electric part of the Weyl tensor vanishes (relative to some timelike unit vector field) are said to be purely magnetic. Examples of purely magnetic spacetimes are known and are relatively easy to construct, if no restrictions are placed on the energy-momentum tensor. However it has long been conjectured that purely magnetic vacuum spa

A. M. Gavrilik

Nonstandard q-deformed algebras U&#39;_q(so_n), proposed a decade ago for the needs of representation theory, essentially differ from the standard Drinfeld-Jimbo quantum deformation of the algebras U(so_n) and possess with regard to the latter a number of important advantages. We discuss possible application of the q-algebras U&#39;_q(so_n), within two diffe

David Delphenich

Some mathematical aspects of using the translation group as an internal symmetry group in a gauge field theory are presented and discussed. The traditional manner in which gravitation can be accounted for by the introduction of a global frame field on a parallelizable spacetime is reviewed. It is then discussed in the more general context of a global frame f

M. Sharif

The time equation associated to the Dirac Equation (DE) is studied for the radiation-dominated Friedmann-Robertson-Walker (FRW) universe. The results are analysed for small and large values of time. We also incorporate the corrections of the paper studied by Zecca [1] for the matter-dominated FRW universe.

B. K. Sahoo, L. P. Singh

We have solved cosmological gravitational Wave(GW)equation in the frame work of Generalised Brans-Dicke(GBD) theory for all epochs of the Universe.The solutions are expressed in terms of the present value of the Brans-Dicke coupling parameter $ω(ϕ)$.It is seen that the solutions represent travelling growing modes for negative values of $ω_{0}$ for all epochs

Slava G. Turyshev, Michael Shao, Kenneth L. Nordtvedt

This paper discusses new fundamental physics experiment to test relativistic gravity at the accuracy better than the effects of the 2nd order in the gravitational field strength. The Laser Astrometric Test Of Relativity (LATOR) mission uses laser interferometry between two micro-spacecraft whose lines of sight pass close by the Sun to accurately measure defl

Ronald de Wolf

We study nondeterministic quantum algorithms for Boolean functions f. Such algorithms have positive acceptance probability on input x iff f(x)=1. In the setting of query complexity, we show that the nondeterministic quantum complexity of a Boolean function is equal to its ``nondeterministic polynomial&#39;&#39; degree. We also prove a quantum-vs-classical ga

Garin F. J Ananos, Constantino Tsallis

Ensemble averages of the sensitivity to initial conditions $ξ(t)$ and the entropy production per unit time of a {\it new} family of one-dimensional dissipative maps, $x_{t+1}=1-ae^{-1/|x_t|^z}(z>0)$, and of the known logistic-like maps, $x_{t+1}=1-a|x_t|^z(z>1)$, are numerically studied, both for {\it strong} (Lyapunov exponent $λ_1>0$) and {\it weak} (chaos

N. Mannella, A. Rosenhahn, C. H. Booth, S. Marchesini

The temperature dependence of the electronic and atomic structure of the colossal magnetoresistive oxides $La_{1-x}Sr_{x}MnO_{3}$ (x = 0.3, 0.4) has been studied using core and valence level photoemission, x-ray absorption and emission, and extended x-ray absorption fine structure spectroscopy. A dramatic and reversible change of the electronic structure is

Sergi Valverde, Ricard V. Sole

Internet is known to display a highly heterogeneous structure and complex fluctuations in its traffic dynamics. Congestion seems to be an inevitable result of user&#39;s behavior coupled to the network dynamics and it effects should be minimized by choosing appropriate routing strategies. But what are the requirements of routing depth in order to optimize th

T. Giamarchi, S. Biermann, A. Georges, A. Lichtenstein

The Bechgaard salts are made of weakly coupled one dimensional chains. This particular structure gives the possibility to observe in these systems a dimensional crossover between a high temperature (or high energy) one dimensional phase and a two or three dimensional system. Since the filling of the chains is commensurate the system thus undergoes a deconfin

M. Allesch, E. Schwegler, F. Gygi, G. Galli

We present the results of Car-Parrinello (CP) simulations of water at ambient conditions and under pressure, using a rigid molecule approximation. Throughout our calculations, water molecules were maintained at a fixed intramolecular geometry corresponding to the average structure obtained in fully unconstrained simulations. This allows us to use larger time

Jesús Casado-Pascual, José Gómez-Ordóñez, Manuel Morillo

We analyze the phenomenon of nonlinear stochastic resonance (SR) in noisy bistable systems driven by pulsed time periodic forces. The driving force contains, within each period, two pulses of equal constant amplitude and duration but opposite signs. Each pulse starts every half-period and its duration is varied. For subthreshold amplitudes, we study the depe

A. G. Angel, M. R. Evans, D. Mukamel

Condensation occurs in nonequilibrium steady states when a finite fraction of particles in the system occupies a single lattice site. We study condensation transitions in a one-dimensional zero-range process with a single defect site. The system is analysed in the grand canonical and canonical ensembles and the two are contrasted. Two distinct condensation m

Zoltan G. Soos, Sharon A. Bewick, Andrea Peri, Anna Painelli

The dipole P(F) of systems with periodic boundary conditions (PBC) in a static electric field F is applied to one-dimensional Peierls-Hubbard models for organic charge-transfer (CT) salts. Exact results for P(F) are obtained for finite systems of N = 14 and 16 sites that are almost converged to infinite chains in deformable lattices subject to a Peierls tran

G. G. N. Angilella, F. E. Leys, N. H. March, R. Pucci

By solution of the Bethe-Goldstone equation for the Cooper pairing problem, an approximate analytic relation is derived between coherence length xi and the binding energy of the Cooper pair. This relation is then qualitatively confirmed by numerically solving the corresponding self-consistent gap equations, following the crossover from weak to strong couplin

Guillaume Gregoire, Hugues Chate, Yuhai Tu

A microscopic, stochastic, minimal model for collective and cohesive motion of identical self-propelled particles is introduced. Even though the particles interact strictly locally in a very noisy manner, we show that cohesion can be maintained, even in the zero-density limit of an arbitrarily large flock in an infinite space. The phase diagram spanned by th

Prabodh Shukla

Recent work on random field Ising model is described briefly emphasizing exact solutions of the model in simple cases and their relevance in understanding equilibrium and non-equilibrium properties of systems with quenched disorder.

Prabodh Shukla

We analyze the energetics of domains and interfaces in the presence of quenched random fields, particularly at the lower critical dimension of the random field Ising model. The relevance of this study to experiments is also discussed.

Prabodh Shukla

The random field Ising model driven by a slowly varying uniform external field at zero temperature provides a caricature of several threshold activated systems. In this model, the non-equilibrium response of the system can be obtained analytically on a Bethe lattice if the initial state of the system has all spins aligned parallel to each other. We consider

J. Tworzydlo, A. Tajic, C. W. J. Beenakker

We calculate the system-size-over-wave-length ($M$) dependence of sample-to-sample conductance fluctuations, using the open kicked rotator to model chaotic scattering in a ballistic quantum dot coupled by two $N$-mode point contacts to electron reservoirs. Both a fully quantum mechanical and a semiclassical calculation are presented, and found to be in good

Christian D. Santangelo, Oded Farago

The free energy of inserting a protein into a membrane is determined by considering the variation in the spectrum of thermal fluctuations in response to the presence of a rigid inclusion. Both numerically and through a simple analytical approximation, we find that the primary effect of fluctuations is to reduce the effective surface tension, hampering the in

P. J. Huggins, C. Muthu, R. Bachiller, T. Forveille

We report high resolution (1-2 arcsec) imaging of the CO 2-1 line and the millimeter continuum in the proto-planetary nebula He 3-1475. The observations reveal the presence of a massive (~0.6 M_sun} envelope of molecular gas around the origin of the remarkable bipolar jet system seen in optical images with the HST. The CO kinematics are well modeled by an ex

D. Branch, R. C. Thomas, E. Baron, D. Kasen

The Type Ia SN 2000cx exhibited multiple peculiarities, including a lopsided B-band light-curve peak that does not conform to current methods for using shapes of light curves to standardize SN Ia luminosities. We use the parameterized supernova synthetic-spectrum code SYNOW to study line identifications in the photospheric-phase spectra of SN 2000cx. Previou

J. Craig Wheeler

This is the text of a summary of the workshop on asymmetric explosions held in Austin in June, 2003. A brief review is given of the author&#39;s own interests in dynamo theory as it may apply in the core collapse ambience. Of particular interest are saturation fields for the cases with central neutron stars and black holes and the possibility of driving MHD

J. Craig Wheeler

This is the text of an introduction to a workshop on asymmetric explosions held in Austin in June, 2003. The great progress in supernova research over thirty-odd years is briefly reviewed. The context in which the meeting was called is then summarized. The theoretical success of the intrinsically multidimensional delayed detonation paradigm in explaining the

L. G. Althaus, A. H. Corsico

We study the structure and evolution of white dwarf stars with helium-rich atmospheres (DB) in a self-consistent way with the predictions of time-dependent element diffusion. Our treatment of diffusion includes gravitational settling and chemical and thermal diffusion. OPAL radiative opacities for arbitrary metallicity and carbon-and oxygen-rich compositions

Daniel C. Homan

The sensitivity, stability, and uniformity of calibration of the VLBA has revolutionized parsec-scale polarization studies of AGN jets. Not only does polarization probe the magnetic field structures of jets, serving as a hydrodynamic tracer of shocks, bends, and shear, but polarization also probes the medium through which it propagates by encoding the signat

D. C. Homan, J. F. C. Wardle

We present multi-frequency, high resolution VLBA circular polarization images of the radio source 3C 84 in the center of NGC 1275. Our images reveal a complex distribution of circular polarization in the inner parsec of the radio jet, with local levels exceeding 3% polarization, the highest yet detected with VLBI techniques. The circular polarization changes

A. J. Weinberger, E. E. Becklin, B. Zuckerman, I. Song

A search for previously undetected optically thin disks around stars in the nearby, young, TW Hydrae Association was conducted around sixteen stars with sensitive 12 and 18 micron photometry. The survey could detect Zodiacal-like dust, with temperature 200-300 K, at levels of L(IR)/L(*)=7e-3. Possible mid-infrared excess emission from TWA 17 was detected at

Andrew Cumming, Jared Macbeth

Superbursts are very energetic Type I X-ray bursts discovered in recent years by long term monitoring of X-ray bursters, and believed to be due to unstable ignition of carbon in the deep ocean of the neutron star. In this Letter, we follow the thermal evolution of the surface layers as they cool following the burst. The resulting lightcurves agree very well

John R. Thorstensen, William H. Fenton, Cynthia J. Taylor

We present spectroscopy of seven cataclysmic variable stars with orbital periods P(orb) greater than 5 hours, all but one of which are known to be dwarf novae. Using radial velocity measurements we improve on previous orbital period determinations, or derive periods for the first time. The stars and their periods are TT Crt, 0.2683522(5) d; EZ Del, 0.2234(5)

Yoel Rephaeli, Duane Gruber

X-ray emission from the cluster of galaxies A3667 was measured by the PCA and HEXTE experiments aboard the RXTE satellite during the period December 2001 - July 2002. Analysis of the ~141 ks RXTE observation and lower energy ASCA/GIS data, yields only marginalevidence for a secondary power-law emission component in the spectrum. The 90% confidence upper limi

D. Teyssier, D. Fosse, M. Gerin, J. Pety

We present a study of small carbon chains and rings in Photon Dominated Regions (PDRs) performed at millimetre wavelengths. Our sample consists of the Horsehead nebula (B33), the rho,Oph L1688 cloud interface, and the cometary-shaped cloud IC63. Using the IRAM 30-m telescope, the SEST and the Effelsberg 100-m teles cope at Effelsberg., we mapped the emission

C. Cabanac, J. Rodriguez, P. O Petrucci, G. Henri

IGR J19140+098 was discovered during the early INTEGRAL observations of GRS1915+105 in March 2003. The following observations by INTEGRAL and RXTE show significant variability on various time scales from 100s to 1ks, but no pulsations. The ISGRI spectra show strong spectral variability in the 20-80keV range. Combined JEMX_2-ISGRI spectra are well fitted by a

Paolo Cabella, Frode Hansen, Domenico Marinucci, Daniele Pagano

We present a comparison between three approaches to test non-Gaussianity of cosmic microwave background data. The Minkowski functionals, the empirical process method and the skewness of wavelet coefficients are applied to maps generated from non-standard inflationary models and to Gaussian maps with point sources included. We discuss the different power of t

T. P. Roberts, R. S. Warwick, M. J. Ward, M. R. Goad

We report the results of a programme of dual-epoch Chandra ACIS-S observations of five ultraluminous X-ray sources (ULXs) in nearby spiral galaxies. All five ULXs are detected as unresolved, point-like X-ray sources by Chandra, though two have faded below the 10^39 erg/s luminosity threshold used to first designate these sources as ULXs. Using this same crit

C. S. Reynolds, J. Wilms, M. C. Begelman, R. Staubert

(abridged) We present a detailed spectral analysis of the first observation of the Seyfert 1 galaxy MCG-6-30-15 by the European Photon Imaging Camera on board the XMM-Newton observatory, together with contemporaneous data from the Proportional Counter Array on the Rossi X-ray Timing Explorer. Confirming our previously published result, we find that the prese

M. Rejkuba, L. Greggio, M. Zoccali

Simulated color-magnitude diagrams (CMDs) are used to investigate the recent star formation history in NGC 5128. The comparison of the simulations with the observed UV CMD for a field in the NE shell, where recent star formation is present, constrains the initial mass function (IMF) and the duration of the star formation episode. The star formation burst is

Cs. Kiss, A. Moor, L. V. Toth

We present the results of an investigation of the large scale structure of the diffuse interstellar medium in the 2nd Galactic Quadrant (90 <= l <= 180). 145 loops were identified on IRAS based far-infrared maps. Our catalogue lists their basic physical properties. The distribution clearly suggests that there is an efficient process that can generate loop-li

L. Pilo, A. Riotto, A. Zaffaroni

The curvaton and the inhomogeneous reheating scenarios for the generation of the cosmological curvature perturbation on large scales represent an alternative to the standard slow-roll scenario where the observed density perturbations are due to fluctuations of the inflaton field itself. The basic assumption of the curvaton and inhomogeneous reheating mechani