May 1999 arXiv papers — page 3

Nikolai Uraltsev

I review the existing theoretical uncertainties in relating the semileptonic decay width in b->u transitions to the underlying Kobayashi-Maskawa mixing element |V_ub|. The theoretical error bars are only a few percent in |V_ub|, with uncertainties from the impact of the nonperturbative effects nearly negligible.

CCFR collaboration, M. Vakili, C. G. Arroyo, P. Auchincloss

Data from the CCFR E770 Neutrino Deep Inelastic Scattering (DIS) experiment at Fermilab contain events with large Bjorken x (x>0.7) and high momentum transfer (Q^2>50 (GeV/c)^2). A comparison of the data with a model based on no nuclear effects at large x, shows a significant excess of events in the data. Addition of Fermi gas motion of the nucleons in the n

L. Lapikas, G. van der Steenhoven, L. Frankfurt, M. Strikman

Existing cross-section data for 1p-shell knockout in the reaction 12C(e,e'p) - as obtained under different kinematic conditions - are shown to be mutually consistent, apart from a recent measurement performed in Mainz. New data have been collected at the Amsterdam Pulse Stretcher that confirm the normalization of the older measurements. An analysis of th

Marek Gazdzicki, Mark I. Gorenstein

The hypothesis of statistical production of J/psi mesons at hadronization is formulated and checked against experimental data. It explains in the natural way the observed scaling behavior of the J/psi to pion ratio at the CERN SPS energies. Using the multiplicities of J/psi and eta mesons the hadronization temperature T_H = 175 MeV is found, which agrees wit

J. J. Halliwell

In the context of the decoherent histories approach to quantum theory, it is shown that a class of macroscopic configurations consisting of histories of local densities (number, momentum, energy) exhibit negligible interference. This follows from the close connection of the local densities with the corresponding exactly conserved (and so exactly decoherent)

N. S. Vidhyadhiraja, A. N. Tahvildar-Zadeh, Mark Jarrell, H. R. Krishnamurthy

We discuss the "exhaustion" problem in the context of the Periodic Anderson Model using Iterated Perturbation Theory(IPT) within the Dynamical Mean Field Theory. We find that, despite its limitations, IPT captures the exhaustion physics, which manifests itself as a dramatic, strongly energy dependent suppression of the effective Anderson impurity pro

L. Lin, K. F. Liu, J. Sloan

We propose a Monte Carlo algorithm to promote Kennedy and Kuti's linear accept/reject algorithm which accommodates unbiased stochastic estimates of the probability to an exact one. This is achieved by adopting the Metropolis accept/reject steps for both the dynamical and noise configurations. We test it on the five state model and obtain desirable result

Marc-Thierry Jaekel, Serge Reynaud

A new quantum algebraic description of relativistic electrons, built on a conformal dynamical symmetry (SO(4,2)), has recently been proposed to treat localization in space-time. It is shown here that localization of an electron may be represented by components of a SO(4,2) vector which are quantum generalizations of the hexaspherical coordinates of classical

Andrzej Ostruszka, Prot Pakonski, Wojciech Slomczynski, Karol Zyczkowski

Dynamics of deterministic systems perturbed by random additive noise is characterized quantitatively. Since for such systems the KS-entropy diverges we analyse the difference between the total entropy of a noisy system and the entropy of the noise itself. We show that this quantity is non negative and in the weak noise limit is conjectured to tend to the KS-

Marc-Andre Lewis

In this short note, we present supporting evidence for the replica symmetric approach to the random bond q-state Potts models. The evidence is statistically strong enough to reject the applicability of the Parisi replica symmetry breaking scheme to this class of models. The test we use is a generalization of one formerly proposed by Dotsenko et al. and consi

J. Baacke, K. Heitmann

The one-loop effective action of the abelian and nonabelian Higgs models has been studied in various gauges, in the context of instanton and sphaleron transition, bubble nucleation and most recently in nonequilibrium dynamics. Gauge invariance is expected on account of Nielsen' s theorem, if the classical background field is an extremum of the classical

Shin'ichi Nojiri, Sergei D. Odintsov

We construct IIB supergravity (viewed as dilatonic gravity) background with non-trivial dilaton and with curved four-dimensional space. Such a background may describe another vacuum of maximally supersymmetric Yang-Mills theory or strong coupling regime of (non)-supersymmetric gauge theory with (power-like) running gauge coupling which depends on curvature.

Masoud Alimohammadi

Using the auxiliary field representation of the simplicial chiral models on a (d-1)-dimensional simplex, the simplicial chiral models are generalized through replacing the term Tr$(AA^{\d})$ in the Lagrangian of these models by an arbitrary class function of $AA^{\d}$; $V(AA^{\d})$. This is the same method used in defining the generalized two-dimensional Yan

G. C. Dewangan, K. P. Singh, P. N. Bhat

We report BVR surface photometry of a lenticular galaxy, NGC4753 with prominent dust lanes. We have used the multicolor broadband photometry to study dust-extinction as a function of wavelength and derived the extinction curve. We find the extinction curve of NGC 4753 to be similar to the Galactic extinction curve in the visible region which implies that the

Gregory Gabadadze, Zurab Kakushadze

We conjecture that a T-dual form of pure QCD describes dynamics of point-like monopoles. T-duality transforms the QCD Lagrangian into a matrix quantum mechanics of zerobranes which we identify with monopoles. At generic points of the monopole moduli space the SU(N) gauge group is broken down to $U(1)^{N-1}$ reproducing the key feature of 't Hooft's A

Xiao-Gang He

We study the unitarity constraint on the two body Higgs boson elastic scattering in the presence of extra dimensions. The contributions from exchange of spin-2 and spin-0 Kaluza-Klein states can have large effect on the partial wave amplitude. Unitarity condition restrict the maximal allowed value for the ratio $r$ of the center of mass energy to the gravity

Jose L. Cereceda

In a recent article [Phys. Rev. A 54, 1793 (1996)] Krenn and Zeilinger investigated the conditional two-particle correlations for the subensemble of data obtained by selecting the results of the spin measurements by two observers 1 and 2 with respect to the result found in the corresponding measurement by a third observer. In this paper we write out explicit

Maksim Kravtsev

In this paper the notion of quantum finite one-counter automata (QF1CA) is introduced. Introduction of the notion is similar to that of the 2-way quantum finite state automata by A.Kondacs and J.Watrous. The well-formedness conditions for the automata are specified ensuring unitarity of evolution. A special kind of QF1CA, called simple, that satisfies the we

K. B. Korotchenko

The basic principles of the quantum mechanics in the K-field formalism are stated in the paper. The basic distinction of this theory arises from that the quantum theory equations (including well-known Schrodinger, Klein-Gordon and quadratic Dirac equations) are obtained from de Broglie postulate geometric generalization. Rather, they are obtained as the free

H. -K. Chung, K. Kirby, J. F. Babb

For the lithium dimer we calculate cross sections for absorption of radiation from the vibrational-rotational levels of the ground X [singlet Sigma g +] electronic state to the vibrational levels and continua of the excited A [singlet Sigma u +] and B [singlet Pi u] electronic states. Theoretical and experimental data are used to characterize the molecular p

T. A. Heim, D. Green

By extending the concept of Euler-angle rotations to more than three dimensions, we develop the systematics under rotations in higher-dimensional space for a novel set of hyperspherical harmonics. Applying this formalism, we determine all pairwise Coulomb interactions in a few-body system without recourse to multipole expansions. Our approach combines the ad

U. Fano, D. Green, J. L. Bohn, T. A. Heim

The quantum dynamical evolution of atomic and molecular aggregates, from their compact to their fragmented states, is parametrized by a single collective radial parameter. Treating all the remaining particle coordinates in d dimensions democratically, as a set of angles orthogonal to this collective radius or by equivalent variables, bypasses all independent

Alexander A. Vlasov

Equation of motion of Sommerfeld sphere in the one-dimensional potential hole, produced by two equal charges on some distance from each other, is numerically investigated. Two types of solutions are found: (i) damping oscillations, (ii) oscillations without damping (radiationless motion). Solutions with growing amplitude ("climbing-up-the-wall solution&#

N. V. Alexeeva, I. V. Barashenkov, G. P. Tsironis

Chains of parametrically driven, damped pendula are known to support soliton-like clusters of in-phase motion which become unstable and seed spatiotemporal chaos for sufficiently large driving amplitudes. We show that the pinning of the soliton on a "long" impurity (a longer pendulum) expands dramatically its stability region whereas "short"

Baruch Meerson, Pavel V. Sasorov, Ken Sekimoto

We report logarithmically slow expansion of hot bubbles in gases in the process of cooling. A model problem first solved, when the temperature has compact support. Then temperature profile decaying exponentially at large distances is considered. The periphery of the bubble is shown to remain essentially static ("glassy") in the process of cooling unt

T. W. Donnelly, Ingo Sick

We investigate the degree to which the concept of superscaling, initially developed within the framework of the relativistic Fermi gas model, applies to inclusive electron scattering from nuclei. We find that data obtained from the low energy loss side of the quasielastic peak exhibit the superscaling property, i.e., the scaling functions f(ψ') are not o

Z. Aouissat, M. Belkacem

A non-perturbative s-wave renormalization of the pion in a hot and baryon rich medium is presented. This approach proceeds via a mapping of the canonical pion into the axial Noether's charge. The mapping was made dynamical in the Hartree-Fock-Bogoliubov random phase approximation (HFB-RPA). It is shown that this approach, while order mixing, is still sym

F. A. Ivanyuk, H. Hofmann

The linear response approach to nuclear transport has been extended to pair correlations. The latter are treated within a mean field approximation to a pairing interaction with constant matrix elements $G$. The constraint of particle number conservation has been accounted for on a time dependent average, which leads to modified response functions, both in th

Corinne A. Manogue, Tevian Dray

A vexing problem involving nonassociativity is resolved, allowing a generalization of the usual complex Mobius transformations to the octonions. This is accomplished by relating the octonionic Mobius transformations to the Lorentz group in 10 spacetime dimensions. The result will be of particular interest to physicists working with lightlike objects in 10 di

Adonai S. Sant'Anna

A condition for the existence of false gauge field copies in terms of the Lefschetz number of a certain differential operator is presented.

Adonai S. Sant'Anna, Newton C. A. da Costa, Francisco A. Doria

K-theory allows us to define an analytical condition for the existence of `false' gauge field copies through the use of the Atiyah-Singer index theorem. After establishing that result we discuss a possible extension of the same result without the help of the index theorem and suggest possible related lines of work.

Topi Kärki

In this thesis, we develop path integral localization methods that are familiar from topological field theory: the integral over the infinite dimensional integration domain depends only on local data around some finite dimensional subdomain. We introduce a new localization principle that unifies BRST localization, the non-Abelian localization principle and t

Birant Ramazan

Let G be a Lie groupoid and L his Lie algebroid. We give a definition of the classical limit of a C^*-bundle and we use the tangent groupoid associated to G to show that the Poisson structure on L is the classical limit of a C^*-bundle.

T. Ward

We consider a family of isometric extensions of the full shift on p symbols (for p a prime) parametrized by a probability space. Using Heath-Brown's work on the Artin conjecture, it is shown that for all but two primes p the set of limit points of the growth rate of periodic points is infinite almost surely. This shows in particular that the dynamical ze

Xavier Buff, Christian Henriksen

Let $f(z)=e^{2iπθ} z+z^2$, where $θ$ is a quadratic irrational. McMullen proved that the Siegel disk for $f$ is self-similar about the critical point. We give a lower bound for the ratio of self-similarity, and we show that if $θ=(\sqrt 5-1)/2$ is the golden mean, then there exists a triangle contained in the Siegel disk, and with one vertex at the critical

Tatsuya Tsukamoto

We give a sufficient condition for an almost alternating link diagram to represent a non-splittable link. The main theorem gives us a way to see if a given almost alternating link diagram represents a splittable link without increasing numbers of crossings of diagrams in the process. Moreover, we show that almost alternating links with more than two componen

Dennis Gaitsgory

We explain the basics of conformal theory using the language of chiral algebras of Beilinson and Drinfeld.

Bogomil Gerganov

The integrability of the N-cosine model, a N-field generalization of the sine-Gordon model, is investigated. We establish to first order in conformal perturbation theory that, for arbitrary N, the model possesses a quantum conserved current of Lorentz spin 3 on a submanifold of the parameter space where the interaction becomes marginal. The integrability of

Timothy J. Hollowood, Valentin V. Khoze, Michael P. Mattis

We consider the multi-instanton collective coordinate integration measure in N=2 supersymmetric SU(N) gauge theory with N_F fundamental hypermultiplets. In the large-N limit, at the superconformal point where N_F=2N and all VEVs are turned off, the k-instanton moduli space collapses to a single copy of AdS_5*S^1. The resulting k-instanton effective measure i

Alfred Scharff Goldhaber

A simple formal computation, and a variation on an old thought experiment, both indicate that QCD with light quarks may confine fundamental color magnetic charges, giving an explicit as well as elegant resolution to the `global color' paradox, strengthening Vachaspati's SU(5) electric-magnetic duality, opening new lines of inquiry for monopoles in co

I T Drummond, R R Horgan, P V Landshoff, A Rebhan

Exact relations between the QCD thermal pressure and the trace anomaly are derived. These are used, first, to prove the equivalence of the thermodynamic and the hydrodynamic pressure in equilibrium in the presence of the trace anomaly, closing a gap in previous arguments. Second, in the temporal axial gauge a formula is derived which expresses the thermal pr

Sen-Ben Liao, Janos Polonyi, Michael Strickland

Renormalization group flow equations for scalar lambda Phi^4 are generated using three classes of smooth smearing functions. Numerical results for the critical exponent nu in three dimensions are calculated by means of a truncated series expansion of the blocked potential. We demonstrate how the convergence of nu as a function of the order of truncation can

Chanju Kim, Soo-Jong Rey

Thermodynamics of d=4, N=4 supersymmetric SU(N) Yang-Mills theory is studied with particular attention on perturbative expansion at weak `t Hooft coupling regime and interpolation to strong coupling regime thereof. Non-ideal gas effect to free-energy is calculated and found that leading- and next-to-leading-order corrections contribute with relative opposite

M. Bordag, M. Hellmund, K. Kirsten

The vacuum energy of a scalar field in a spherically symmetric background field is considered. Based on previous work [hep-th/9608070], the numerical procedure is refined further and applied to several examples. We provide numerical evidence that repulsive potentials lead to positive contributions to the vacuum energy. Furthermore, the crucial role played by

P. Mukherjee

We show that the degeneracy of topological solitons in the gauged O(3) non-linear sigma model with Chern-Simons term may be removed by chosing a self-interaction potential with symmetry - breaking minima. The topological solitons in the model has energy,charge,flux and angular momentum quantised in each topological sector.

Bo-yu Hou, Kang-jie Shi, Wen-li Yang

In this paper, we give the general crossing relation for boundary reflection matrix $R(β)$, which is the extension of the work given by Ghoshal and Zamolodchikov .We also use the first non-trivial extended crossing relation to determine the scaler factor of $R(β)$ which is the rational diagonal solution to the boundary Yang-Baxter equation in the case of l=2

H. Awata, S. Hirano, Y. Hyakutake

We study a membrane -- anti-membrane system in Matrix theory. It in fact exhibits the tachyon instability. By suitably representing this configuration, we obtain a (2+1)-dimensional U(2) gauge theory with a 't Hooft's twisted boundary condition. We identify the tachyon field with a certain off-diagonal element of the gauge fields in this model. Takin

Yves Sirois

The early observation at HERA of an excess of events compared to the expectation from the Standard Model in very short distance $e^+p$ deep-inelastic scattering processes has renewed the interest in the search for new physics which could manifest in electroweak-like interactions. New preliminary results from the H1 and ZEUS experiments making use of all avai

Christian Schubert

We present an extension of the string-inspired technique suitable to the calculation of amplitudes and effective Lagrangians involving both vector and axial vector gauge fields. The technique is easily adaptable to problems involving constant external fields. We demonstrate the advantages of the formalism by a calculation of the one-loop vector-axialvector a

J. Blumlein, A. Tkabladze

The nucleon mass corrections are calculated to all polarized structure functions for neutral and charged current deep inelastic scattering in lowest order in the coupling constant. The impact of the target mass corrections on the general relations between the twist--2 and twist--3 parts of the structure functions is studied and three new relations between th

C. S. Lam

A formula to unitarize the leading-log BFKL-Pomeron amplitude is derived using a coherent property of two-body collision in the peripheral region. This procedure also allows an algebraic characterization of the Reggeon in QCD based on color, instead of the total angular momentum of the gluons being exchanged.

E. R. Berger

We consider exclusive $π^0$ production in ep-scattering. At high energies odderon and photon exchange contribute. The photon exchange contribution is evaluated exactly using data for the total virtual photon-proton absorption cross section. The odderon exchange contribution is calculated in nonperturbative QCD, using functional integral techniques and the mo

M. Botje

The parton momentum densities in the proton are obtained from a NLO QCD analysis of structure functions measured by HERA and fixed target experiments. The uncertainties in these parton densities, the structure functions and related cross sections are estimated from the experimental errors, taking into account all correlations. Standard Model predictions for

K. Golec-Biernat, A. D. Martin, M. G. Ryskin

We briefly discuss the problem of specifying initial conditions for evolution of off-diagonal (skewed) parton distributions. We present numerical results to show that evolution rapidly washes out differences of input.

A. Szczurek, V. Uleshchenko

We make a few remarks on possible sources of uncertainties of the $\bar d - \bar u$ asymmetry obtained by different methods and comment on its possible verification in the future. In addition we comment on its present understanding.

K. Golec-Biernat, A. D. Martin, M. G. Ryskin, A. G. Shuvaev

We show that the skewed parton distributions are completely determined at small x and ξby the conventional diagonal partons. We study the application to diffractive vector meson production at HERA.

J. Blümlein, V. Ravindran, W. L. van Neerven

We study the scheme transformation of next to leading order QCD corrections to various processes. An interesting relation by Drell, Levy and Yan (DLY) among space like and time like processes is studied carefully in the next to leading order level. We construct factorisation scheme invariants and show that they are DLY-invariant.

Elliot Leader, Alexsander V. Sidorov, Dimiter B. Stamenov

We present a new next-to-leading order QCD analysis of the world data on inclusive polarized deep inelastic lepton-nucleon scattering adding to the old set of data the final SMC results, the HERMES proton and very recent SLAC/E155 deuteron data. We find an excellent fit to the data and present results for the polarized parton densities in different factoriza

G. P. Skoro, M. Zupan, M. V. Tokarev

The prompt photon production in p-p collisions at high energies is studied. Double-spin asymmetry of the process is calculated by using Monte Carlo code SPHINX. A possibility to discriminate the spin-dependent gluon distributions and to determine sign of Delta G is discussed. Detailed study of expected background, such as pi0 production and decay, is given.

Salavat Abdullin, Daniel Denegri

We investigate the probability to find a b or tau in SUSY production with the mSUGRA model. We find that in the entire parameter space the probability per event to find a b-jet of E_T^b > 50 GeV within CMS acceptance (eta < 2.4) is significant for all tan(beta), varying from a 10 % level to 90 % depending on the m_0, m_1/2 region. The probabilities per event

F. Simkovic, G. Pantis, J. D. Vergados, A. Faessler

We have examined the importance of momentum dependent induced nucleon currents such as weak-magnetism and pseudoscalar couplings to the amplitude of neutrinoless double beta decay in the mechanisms of light and heavy Majorana neutrino as well as in that of Majoron emission. Such effects are expected to occur in all nuclear models in the direction of reducing

Barbara Clerbaux

Results on elastic vector meson production at HERA are presented in the framework of perturbative QCD. The energy dependence of the cross section for J/Psi photoproduction and for rho electroproduction is studied. A full polarisation analysis, including the measurement of the 15 elements of the spin density matrix and of R=sigma_L/sigma_T, is presented for r

Barbara Clerbaux

Results on elastic electroproduction of rho mesons are presented for a photon virtuality in the range 1 < Q^2 < 60 GeV^2 and for a hadronic centre of mass energy in the range 30 < W < 140 GeV. The shape of the (pi pi) mass distribution is discussed and measurements of the cross section dependences on Q^2, W and t (the four-momentum transfer squared to the pr

Paolo Lipari

The predictions of the atmospheric nu event rates are affected by significant uncertainties, however the evidence for the `disappearance&#39; of nu_mu&#39;s and antinu_mu&#39;s obtained by SK and other underground detectors is robust and cannot be accounted in the framework of the minimum standard model without assuming very large ad hoc experimental systema

Roland Windmolders

Recent results in polarized DIS are reviewed. Particular emphasis is placed on new measurements of transverse and longitudinal asymmetries, on the tests of the spin sum rules and on the analysis of the spin structure function $g_1$ in perturbative QCD at NLO.

Wei Liu, Bin Zhang, Hanqing Zheng

We re-estimate the decay branching ratio of $B_s\to 2γ$ through $D_s^+D_s^-$ and $D_s^{*+}D_s^{*-}$ intermediate states, in the effective Lagrangian approach. We find that the branching ratio does not exceed a few times $10^{-7}$, contrary to the result recently claimed in the literature.

W. L. van Neerven

Exploration of the small $x$ kinematic region by the HERA experiments led to a revival of some models which existed before the advent of Quantum Chromo Dynamics (QCD) as the theory of the strong interactions. Predictions of these models for the deep inelastic structure functions are compared with those given by QCD. Future experiments will concentrate on the

T. Umekawa, K. Naito, M. Oka

The Wilsonian renormalization group (RG) method is applied to finite temperature systems for the study of non-perturbative methods in the field theory. We choose the O(N) linear sigma model as the first step. Under the local potential approximation, we solve the Wilsonian RG equation as a non-linear partial differential equation numerically. The evolution of

R. Delbourgo, Dongsheng Liu, M. D. Scadron

We show that all abnormal parity three-body meson interactions can be adequately described by quark loops, evaluated at zero external momentum, with couplings determined by $U(N_f)$ symmetry. We focus primarily on radiative meson decays which involve one pseudoscalar. The agreement with experiment for non-rare decays is surprisingly good and requires very fe

M. Wing

The production of heavy quarks has been studied in photoproduction processes with the ZEUS detector at HERA using an integrated luminosity of $36.9 pb^{-1}$. Events with a photon virtuality, $Q^2<1 GeV^2$, were selected with two jets of high transverse energy and an electron in the final state. Consideration of the distribution in $p_T^{rel}$ - the momentum

A. Edery

We show that it is not possible in the absence of dark matter to construct a four-dimensional metric that explains galactic observations. In particular, by working with an effective potential it is shown that a metric which is constructed to fit flat rotation curves in spiral galaxies leads to the wrong sign for the bending of light i.e. repulsion instead of

J. D. Barrow, Y. Gaspar, P. M. Saffin

We report some new exact instantons in general relativity. These solutions are Kähler and fall into the symmetry classes of Bianchi types VI0 and VII0, with matter content of a stiff fluid. The qualitative behaviour of the solutions is presented, and we compare it to the known results of the corresponding self-dual Bianchi solutions. We also give axisymmetri

Fernando de Felice, Liu Siming, Yu Yunqiang

We present new results concerning the existence of static, electrically charged, perfect fluid spheres that have a regular interior and are arbitrarily close to a maximally charged black-hole state. These configurations are described by exact solutions of Einstein&#39;s field equations. A family of these solutions had already be found (de Felice et al., 1995

A. Barvinsky, A. Kamenshchik, C. Kiefer

We give a consistent description of how the inflationary Universe emerges in quantum cosmology. This involves two steps: Firstly, it is shown that a sensible probability peak can be obtained from the cosmological wave function. This is achieved by going beyond the tree level of the semiclassical expansion. Secondly, due to decoherence interference terms betw

W. B. Belayev

We consider cosmological model in 4+1 dimensions with variable scale factor in extra dimension and static external space. The time scale factor is changing. Variations of light velocity, gravity constant, mass and pressure are determined with four-dimensional projection of this space-time. Data obtained by space probes Pioneer 10/11 and Ulysses are analyzed

M. Chaves

Software for the resolution of certain kind of problems, those that rate high in the Stringent Performance Objectives adjustment factor (IFPUG scheme), can be described using a combination of game theory and autonomous systems. From this description it can be shown that some of those problems exhibit chaotic behavior, an important fact in understanding the f

Jean-Philippe Bouchaud, Marc Potters

Risk control has become one of the major concern of financial institutions. The need for adequate statistical tools to measure and anticipate the amplitude of the potential moves of financial markets is clearly expressed, in particular for derivative markets. Classical theories, however, are based on simplified assumptions -- such as Gaussian statistics -- a

B. Mehlig, M. Wilkinson

We give a transparent derivation of a relation obtained using a supersymmetric non-linear sigma model by Andreev and Altshuler [Phys. Rev. Lett. 72, 902, (1995)], which connects smooth and oscillatory components of spectral correlation functions. We show that their result is not specific to random matrix theory. Also, we show that despite an apparent contrad

M. Ibanes, J. Garcia-Ojalvo, R. Toral, J. M. Sancho

We present a study of a phase-separation process induced by the presence of spatially-correlated multiplicative noise. We develop a mean-field approach suitable for conserved-order-parameter systems and use it to obtain the phase diagram of the model. Mean-field results are compared with numerical simulations of the complete model in two dimensions. Addition

Normand Mousseau, G. T. Barkema

At low temperatures, dynamics in amorphous silicon occurs through a sequence of discrete activated events that locally reorganize the topological network. Using the activation-relaxation technique, a data base containing over 8000 such events is generated, and the events are analyzed with respect to their energy barrier and asymmetry, displacement and volume

L. Pitaevskii, S. Stringari

We suggest an experiment to investigate the linear superposition of two spatially separated Bose-Einstein condensates. Due to the coherent combination of the two wave functions, the dynamic structure factor, measurable through inelastic photon scattering at high momentum transfer $q$, is predicted to exhibit interference fringes with frequency period $Δν= q/

Jonathan Doye, David Wales

In recent experiments on sodium chloride clusters structural transitions between nanocrystals with different cuboidal shapes were detected. Here we presents results for the thermodynamics and dynamics of one of these clusters, (NaCl)35Cl-. As the time scales for the structural transitions can be much longer than those accessible by conventional dynamics simu

Minzhong Xu, Xin Sun

The static current operator leads to definitional zero frequency divergence and unphysical results in studying nonlinear optical susceptibilities of polymers. A well-defined dipole-dipole correlation is superior to the complicated current-current correlation to solve this problem. As illustrative examples, optical susceptibilities under both SSH and TLM mode

J. Ortner

This paper investigates the effect of correlations in electronic bilayers on the longitudinal collective mode structure. We employ the dielectric permeability constructed by means of the classical theory of moments. It is shown that the neglection of damping processes overestimates the role of correlations. We conclude that the correct account of damping pro

Supriya Krishnamurthy, Vittorio Loreto, Stephane Roux

Using a simple lattice model for granular media, we present a scenario of self-organization that we term self-organized structuring where the steady state has several unusual features: (1) large scale space and/or time inhomogeneities and (2) the occurrence of a non-trivial peaked distribution of large events which propagate like ``bubbles&#39;&#39; and have

Eshel Ben-Jacob, Ziv Hermon, Alexsander Shnirman

We first present open questions related to the foundations of thermodynamics and statistical physics. We then argue that in principle one can not have &#34;closed systems&#34;, and that a universal background should exist. We propose that the gravitational field plays this role, due to its vanishing energy-momentum tensor. This leads to a new possible pictur

G. Neuttiens, C. Strunk, C. Van Haesendonck, Y. Bruynseraede

We report on intrinsic time-dependent conductance fluctuations observed in mesoscopic AuFe spin glass wires. These dynamical fluctuations have a 1/f-like spectrum and appear below the measured spin glass freezing temperature of our samples. The dependence of the fluctuation amplitude on temperature, magnetic field, voltage and Fe concentration allows a consi

L. Kipp, K. Rossnagel, J. Brugmann, C. Solterbeck

Angle resolved photoemission spectroscopy (ARPES) has been commonly applied to evaluate the shape of Fermi surfaces by employing simple criteria for the determination of the Fermi vector k_F parallel to the surface such as maximum photoemission intensity at the Fermi level or discontinuity in the momentum distribution function. Here we show that these criter

D. Menashe, B. Laikhtman

We use a diagrammatic approach to study low energy physics of a two dimensional electron system where the Fermi level is near van-Hove singularies in the energy spectrum. We find that in most regions of the $ε_F-T$ phase diagram the system behaves as a normal Fermi liquid rather than a marginal Fermi liquid. Particularly, the imaginary part of the self energ

Mark I. Visscher, Gerrit E. W Bauer

We propose to operate a locally-gated charge density wave as an electron pump. Applying an oscillating gate potential with frequency $f$ causes equally spaced plateaux in the sliding charge density wave current separated by $ΔI=2eNf,$ where $N$ is the number of parallel chains. The effects of thermal noise are investigated.

M. Bachmann, H. Kleinert, A. Pelster

We calculate analytically the proportionality constant in the pressure law of a membrane between parallel walls from the strong-coupling limit of variational perturbation theory up to third order. Extrapolating the zeroth to third approximations to infinity yields the pressure constant alpha=0.0797149. This result lies well within the error bounds of the mos

D. Meyer, W. Nolting

We investigate the influence of an interband exchange interaction on magnetism in a two-band Hubbard model. Our main emphasis lies on spin-flip scattering which is often neglected but is neccessary to retain the full rotational symmetry of the Hamiltonian. We find a striking dependence of the magnetization on the interband exchange coupling constant J and a

Massimo Campostrini, Andrea Pelissetto, Paolo Rossi, Ettore Vicari

We determine the critical exponents for the XY universality class in three dimensions, which is expected to describe the $λ$-transition in ${}^4$He. They are obtained from the analysis of high-temperature series computed for a two-component $λϕ^4$ model. The parameter $λ$ is fixed such that the leading corrections to scaling vanish. We obtain $ν= 0.67166(55)

J. O. Fjaerestad, A. Sudbo

We investigate the effect of k-space broadening of the interlayer pairing kernel on the critical temperature T_c and the k-dependence of the gap function in a one-dimensional version of the interlayer pair-tunneling model of high-T_c superconductivity. We consider constant as well as k-dependent intralayer pairing kernels. We find that the sensitivity to k-s

R. W. Romani, A. J. Miller, B. Cabrera, E. Figueroa-Feliciano

We report on the first astronomical observations with a photon counting pixel detector that provides arrival time- (delta t = 100ns) and energy- (delta E_gamma < 0.15eV) resolved measurements from the near IR through the near UV. Our test observations were performed by coupling this Transition Edge Sensor (TES) device to a 0.6m telescope; we have obtained th

Sergei Nayakshin, Saul Rappaport, Fulvio Melia

We investigate different accretion disk models and viscosity prescriptions in order to provide a basic explanation for the exotic temporal behavior in GRS 1915+105. Based on the fact that the overall cycle times are very much longer than the rise/fall time scales in GRS 1915, we rule out the geometry of ADAF or a hot quasi-spherical region plus a cold outer

Inese I. Ivans, Christopher Sneden, Robert P. Kraft, Nicholas B. Suntzeff

We present a chemical composition analysis of 36 giants in the nearby mildy metal-poor (<[Fe/H]> = -1.18) &#34;CN-bimodal&#34; globular cluster M4. Confronted with a cluster that has large and variable interstellar extinction across the cluster face, we combined traditional spectroscopic abundance methods with modifications to line-depth ratio techniques to

Xuelei Chen, Marc Kamionkowski

We develop a formalism for calculating cosmic microwave background (CMB) temperature and polarization anisotropies in cosmological models with Brans-Dicke gravity. We then modify publicly available Boltzmann codes to calculate numerically the temperature and polarization power spectra. Results are illustrated with a few representative models. Comparing with

Frank J. Low, Dean C. Hines, Glenn Schneider

Spectral energy distributions (SEDs) from 0.4 to 4.7 microns are presented for the two principal stellar components of HD~98800, A and B. The third major component, an extensive planetary debris system (PDS), emits > 20% of the luminosity of star B in a blackbody SED at 164 +/- 5K extending from mid-IR to millimeter-wavelengths. At 0.95 microns a preliminary

R. M. Sambruna, M. Eracleous, R. F. Mushotzky

We present a uniform and systematic analysis of the 0.6-10 keV X-ray spectra of radio-loud active galactic nuclei (AGN) observed by ASCA. The sample 10 BLRGs, 5 QSRs, 9 NLRGs, and 10 RGs. At soft X-rays, about half of the NLRGs and all of the RGs exhibit a thermal plasma component, with a bimodal distribution of temperatures and luminosities, suggesting an o