September 2002 arXiv papers — page 16

Nicolas Andruskiewitsch, Sonia Natale

Let k be a field. Let also (F, G) be a matched pair of groups. We give necessary and sufficient conditions on a pair (σ, τ) of 2-cocycles in order that the crossed product algebra and the crossed coproduct coalgebra k^G{}^τ#_σ kF combine into a braided Hopf algebra. We also discuss diagonal realizations of such braided Hopf algebras in the category of Yetter

Hajime Aoki, Satoshi Iso, Keiichi Nagao

We investigate chiral anomaly for fermions in fundamental representation on noncommutative (fuzzy) 2-sphere. In spite that this system is realized by finite dimensional matrices and no regularization is necessary for either UV or IR, we can reproduce the correct chiral anomaly which is consistent with the calculations done in flat noncommutative space. Like

Karl-Peter Marzlin, Stephen D. Bartlett, Barry C. Sanders

We introduce the entanglement gauge describing the combined effects of local operations and nonlocal unitary transformations on bipartite quantum systems. The entanglement gauge exploits the invariance of nonlocal properties for bipartite systems under local (gauge) transformations. This new formalism yields observable effects arising from the gauge geometry

Konstantinos Dimopoulos, David H. Lyth

It is usually supposed that inflation is of the slow-roll variety, and that the inflaton generates the primordial curvature perturbation. According to the curvaton hypothesis, inflation need not be slow-roll, and if it is the inflaton generates a negligible curvature perturbation. We find that the construction of slow-roll inflation models becomes much easie

A. L. Migdall, D. Branning, S. Castelletto, M. Ware

As currently implemented, single-photon sources cannot be made to produce single photons with high probability, while simultaneously suppressing the probability of yielding two or more photons. Because of this, single photon sources cannot really produce single photons on demand. We describe a multiplexed system that allows the probabilities of producing one

R. F. Bishop, C. Emary

The Rabi Hamiltonian describes a single mode of electromagnetic radiation interacting with a two-level atom. Using the coupled cluster method, we investigate the time evolution of this system from an initially empty field mode and an unexcited atom. We give results for the atomic inversion and field occupation, and find that the virtual processes cause the f

T. Heinonen, P. Lahti, J. -P. Pellonpaa

Covariant phase difference observables are determined in two different ways, by a direct computation and by a group theoretical method. A characterization of phase difference observables which can be expressed as difference of two phase observables is given. Classical limit of such phase difference observables are determined and the Pegg-Barnett phase differ

Tarak Nath Dey, G. S. Agarwal

We investigate whether it is possible to store and retrieve the intense probe pulse from a $Λ$-type homogeneous medium of cold atoms. Through numerical simulations we show that it is possible to store and retrieve the probe pulse which are not necessarily weak. As the intensity of the probe pulse increases, the retrieved pulse remains a replica of the origin

Daniel Gottesman, Hoi-Kwong Lo

Shor and Preskill have provided a simple proof of security of the standard quantum key distribution scheme by Bennett and Brassard (BB84) by demonstrating a connection between key distribution and entanglement purification protocols with one-way communications. Here we provide proofs of security of standard quantum key distribution schemes, BB84 and the six-

H. C. Rosu

Aristotle was the first to declare himself in the class of natural philosophers ({\em physiologoi}) and he was the first physicist because he spelled out the first definitions of some basic physical concepts. Moreover, he was the first encyclopedist of the world and perhaps the greatest

S. G. Tantawi, C. Nantista, N. Kroll, Z. Li

The Delay Line Distribution System (DLDS) is an alternative to conventional pulse compression, which enhances the peak power of rf sources while matching the long pulse of those sources to the shorter filling time of accelerator structures. We present an implementation of this scheme that combines pairs of parallel delay lines of the system into single lines

Sigmund Kohler, Jörg Lehmann, Sébastien Camalet, Peter Hänggi

We investigate the influence of external laser excitations on the average current through bridged molecules. For the computation of the current, we use a numerically very efficient formalism that is based on the Floquet solutions of the time-dependent molecule Hamiltonian. It is found that the current as a function of the laser frequency exhibits characteris

J. M. Hickmann, D. Solli, C. F. McCormick, R. Plambeck

We have measured the photonic bandgap in the transmission of microwaves through a two-dimensional photonic crystal slab. The structure was constructed by cementing acrylic rods in a hexagonal closed-packed array to form rectangular stacks. We find a bandgap centered at approximately 11 GHz, whose depth, width and center frequency vary with the number of laye

Michael Meyer-Hermann, Frido Erler, Gerhard Soff

We present a new model for the dynamics of the presynaptic intracellular calcium concentration in neurons evoked by various stimulation protocols. The aim of the model is twofold: We want to discuss the calcium transients during and after specific stimulation protocols as they are used to induce long-term-depression and long-term-potentiation. In addition we

Pieter Maris

The Dyson-Schwinger equations of QCD, truncated to ladder-rainbow level, are used to calculate meson form factors in impulse approximation. The infrared strength of the ladder-rainbow kernel is described by two parameters fitted to the chiral condensate and f_pi; the ultraviolet behavior is fixed by the QCD running coupling. This obtained elastic form factor

Michail P. Rekalo, Egle Tomasi-Gustafsson

We establish the model-independent spin structure of the matrix elements for the near-threshold scalar meson production in $pp-$ and $np$-collisions, when the final particles are emitted in S-state. Polarization phenomena are derived in a general form. The properties of the $t-$channel dynamics, which is based on different meson exchanges, are studied in ter

A. M. Rucklidge, W. J. Rucklidge

Spatial Fourier transforms of quasipatterns observed in Faraday wave experiments suggest that the patterns are well represented by the sum of 8, 10 or 12 Fourier modes with wavevectors equally spaced around a circle. This representation has been used many times as the starting point for standard perturbative methods of computing the weakly nonlinear dependen

Marcelo Gleiser, Rafael C. Howell

This paper has been withdrawn. A much-improved version can be found at hep-ph/0209176.

Elliott H. Lieb

A survey of the stability of matter problem is given, starting with the stability of the hydrogen atom. The stablity of bulk matter with Coulomb potentials, with or without relativistic mechanics, and with or without magnetic fields is discussed. The final section discusses the stability of matter in a relativistic model with the Dirac operator as kinetic en

Richard F. Booth, Alexandre V. Borovik, Neil White

We introduce the concept of orientation for Lagrangian matroids represented in the flag variety of maximal isotropic subspaces of dimension N in the real vector space of dimension 2N+1. The paper continues the study started in math.CO/0209100.

Thomas Marley, Janet C. Vassilev

Let R be a regular local ring of dimension d, I an ideal of R, and M a finitely generated R-module of dimension n. We prove that the set of associated primes of Ext^i_R(R/I,H^j_I(M)) is finite for all i and j in the following cases: (1) dim M\le 3; (2) dim R\le 4; (3) dim M/IM \le 2 and M satisfies Serre's condition S_{n-3}; (4) dim M/IM\le 3, R is unram

Sonia Martinez, Jorge Cortes, Francesco Bullo

Motion planning and control are key problems in a collection of robotic applications including the design of autonomous agile vehicles and of minimalist manipulators. These problems can be accurately formalized within the language of affine connections and of geometric control theory. In this paper we overview recent results on kinematic controllability and

Luen-Chau Li, Serge Parmentier

We address the question of duality for the dynamical Poisson groupoids of Etingof and Varchenko over a contractible base. We also give an explicit description for the coboundary case associated with the solutions of the classical dynamical Yang-Baxter equation on simple Lie algebras as classified by the same authors. Our approach is based on the study of a c

Biswaranjan Behera

We introduce an equivalence relation on the set of single wavelets of L^2(R^n) associated with an arbitrary dilation matrix. The corresponding equivalence classes are characterized in terms of the support of the Fourier transform of wavelets and it is shown that each of these classes is non-empty.

M. Teicher T. Ben-Itzhak

In this paper we prove certain Hurwitz equivalence properties in the braid group. Our main result is that every two factorizations of $Δ_n ^2$ where the elements of the factorization are semi-frame are Hurwitz equivalent. The results of this paper are generalization of the results in \cite{B4}. We use a new presentation of the braid group, called the Birman-

Th. Gallay, A. Mielke

We study a coarsening model describing the dynamics of interfaces in the one-dimensional Allen-Cahn equation. Given a partition of the real line into intervals of length greater than one, the model consists in constantly eliminating the shortest interval of the partition by merging it with its two neighbors. We show that the mean-field equation for the time-

P. Bieliavsky, M. Pevzner

This article is a contribution to the domain of (convergent) deformation quantization of symmetric spaces by use of Lie groups representation theory. We realize the regular representation of $SL(2,\R)$ on the space of smooth functions on the Poincaré disc as a sub-representation of $SL(2,\R)$ in the Weyl-Moyal star product algebra on $\R^2$. We indicate how

Stephane Druel

Soit (V,o) une singularité symplectique isolée de dimension au moins 6 et soit p : $X\longrightarrow V$ l'éclatement normalisé de o dans V. On suppose que le diviseur $p^{-1}(o)$ est réduit, globalement à croisements normaux et qu'il a au moins deux composantes irréductibles. Alors (V,o) est analytiquement isomorphe au quotient de l'espace affine

Massimo Campostrini, Jacek Wosiek

A new, recursive method of calculating matrix elements of polynomial hamiltonians is proposed. It is particularly suitable for the recent algebraic studies of the supersymmetric Yang-Mills quantum mechanics in any dimensions. For the D=2 system with the SU(2) gauge group, considered here, the technique gives exact, closed expressions for arbitrary matrix ele

Mina Aganagic, Cumrun Vafa

We provide a purely perturbative (one loop) derivation of mirror symmetry for supersymmetric sigma models in two dimensions.

Ricardo Bentin

We start from the well-known form of the interval of the special relativity, stare it, and build up an attempt to implement the causality from it. Some features appear to be new, they involve the mass of the particle and the structure of space-time.

Carlos Castro

Four years ago the Extended Scale Relativity (ESR) theory in C-spaces (Clifford manifolds) was proposed as the plausible physical foundations of string theory. In such theory the speed of light and the minimum Planck scale are the two universal invariants. All the dimensions of a C-space can be treated on equal footing by implementing the holographic princip

Thomas K. Gaisser

This talk is a status report on calculations of the flux of atmospheric neutrinos from the sub-GeV range to E_ν~ PeV. In the lower energy range (E_ν< 1 TeV) the primary interest is in using the atmospheric neutrino beam to study neutrino oscillations. In the TeV range and above, atmospheric neutrinos are a calibration source and background for neutrino teles

V. A. Smirnov

The leading power asymptotic behaviour of the dimensionally regularized massless on-shell planar triple box diagram in the Regge limit t/s -> 0 is analytically evaluated.

A. Salim Safir

We calculate the independent helicity amplitudes in the decays $B \to K^* \ell^+ \ell^-$ and $B \to ρ\ell ν_\ell$ in the so-called Large-Energy-Effective-Theory (LEET). Taking into account the dominant $O(α_s)$ and SU(3) symmetry-breaking effects, we calculate various single (and total) distributions in these decays making use of the presently available data

Kuang-Ta Chao, Li-Kun Hao

We review the charmonium production in $e^+e^-$ annihilation at $\sqrt{s}=10.6GeV$. NRQCD predictions for the $J/ψ$ production are compared with the recent measurements by BaBar and Belle. A NRQCD calculation for the $D$-wave charmonium production is reported to further test the color-octet mechanism and detect the $J^{PC}=2^{--}$ state. The issue of double

Sandrine Laplace

The implications of the most recent experimental results in the B and K meson systems on the CKM paradigm are investigated by means of a global fit to the theoretical predictions of the Standard Model. We advocate the frequentist approach Rfit, which is implemented in the CKMFitter package. Within this approach, constraints on the CKM parameters and other qu

Gosta Gustafson, Leif Lonnblad, Gabriela Miu

We apply the Linked Dipole Chain model to hadronic collisions using a modified version of the LDCMC Monte Carlo program. In particular we investigate the effects of multiple scatterings, which in this framework are reformulated in terms of the production of multiple chains of dipoles. We find, among other things, that this way of describing multiple scatteri

W. M. Alberico, C. Ratti

The minimum energy per baryon number of strange quark matter is studied, as a function of the strangeness fraction, in the MIT bag model and in two different versions of the Color Dielectric Model: a comparison is made with the hyperon masses having the same strangeness fraction, and coherently calculated within both models. Calculations are carried out in m

A. Rusetsky

In the perturbative field-theoretical models we investigate the inclusion of the electromagnetic interactions into the purely strong theory that describes hadronic processes. In particular, we study the convention for splitting electromagnetic and strong interactions and the ambiguity of such a splitting. The issue of the interpretation of the parameters of

Gary R. Goldstein, Leonard Gamberg

Both meson photoproduction and semi-inclusive deep inelastic scattering can potentially probe transversity in the nucleon. We explore how that potential can be realized dynamically. The role of rescattering in both exclusive and inclusive meson production as a source for transverse polarization asymmetry is examined. We use a dynamical model to calculate the

V. V. Bytev, E. A. Kuraev, B. G. Shaikhatdenov

Part of eikonal type contributions to $eμ$ large-angle high-energy scattering cross section is considered in a quasi-elastic experimental set-up. Apart from virtual corrections we examine inelastic processes with emission of one and two soft real photons as well as soft lepton and pion pairs. Virtual photon contributions are given within a logarithmic accura

D. Becirevic, V. Gimenez, V. Lubicz, G. Martinelli

We present new results for the renormalisation and subtraction constants for the four fermion Delta F=2 operators, computed non-perturbatively in the RI-MOM scheme (in the Landau gauge). From our preliminary analysis of the lattice data at beta=6.45, for the B-bar B mixing bag-parameter we obtain B_B^{RGI} = 1.46(7)(1).

I. T. Drummond, A. Hart, R. R. Horgan, L. C. Storoni

We calculate the two loop Landau mean links and the one loop renormalisation of the anisotropy for Wilson and improved SU(3) gauge actions, using twisted boundary conditions as a gauge invariant infrared regulator. We show these accurately describe simulated results, and outline a method for generating Feynman rules for general lattice field theories, in a f

P. O. Bowman, U. M. Heller, D. B. Leinweber, A. G. Williams

The quark propagator is at the core of lattice hadron spectrum calculations as well as studies in other nonperturbative schemes. We investigate the quark propagator with an improved staggered action (Asqtad) and an improved gluon action, which provides good quality data down to small quark masses. This is used to construct ans\"{a}tze suitable for model hadr

T. Nakaya

This paper presents the recent results from Super-Kamiokande atmospheric neutrinos and from K2K accelerator neutrinos. Both results show the signal of neutrino oscillation, and provide new and precise information of oscillation parameters. The oscillation parameters are constraint to be between 1.5*10^{-3} eV^2 and 3.9*10^{-3} eV^2 for Δm^2 and to be greater

N. C. R. Makins

Results from the HERMES experiment are presented on single-spin asymmetries in semi-inclusive hadron production from longitudinally polarized targets. The data are compared with a number of theoretical calculations which relate the azimuthal dependence of the asymmetries to the transversity structure function h_1(x).

Nicholas G Phillips, B. L. Hu

Continuing our investigation of the regularization of the noise kernel in curved spacetimes [N. G. Phillips and B. L. Hu, Phys. Rev. D {\bf 63}, 104001 (2001)] we adopt the modified point separation scheme for the class of optical spacetimes using the Gaussian approximation for the Green functions a la Bekenstein-Parker-Page. In the first example we derive t

Nicholas G Phillips, B. L. Hu

In Paper II [N. G. Phillips and B. L. Hu, previous abstract] we presented the details for the regularization of the noise kernel of a quantum scalar field in optical spacetimes by the modified point separation scheme, and a Gaussian approximation for the Green function. We worked out the regularized noise kernel for two examples: hot flat space and optical S

A. A. Kirillov, G. Montani

We derive a ``generic&#39;&#39; inhomogeneous ``bridge&#39;&#39; solution for a cosmological model in the presence of a real self-interacting scalar field. This solution connects a Kasner-like regime to an inflationary stage of evolution and therefore provides a dynamical mechanism for the quasi-isotropization of the universe. In the framework of a standard

M. Novello, S. E. Perez Bergliaffa, K. E. Hibberd

We investigate a static solution with spherical symmetry of a recently proposed field theory of gravitation. In this so-called NDL theory, matter interacts with gravity in accordance with the Weak Equivalence Principle, while gravitons have a nonlinear self-interaction. It is shown that the predictions of NDL agree with those of General Relativity in the thr

Mihalis Dafermos

This talk describes some recent results [16] regarding the problem of uniqueness in the large (also known as strong cosmic censorship) for the initial value problem in general relativity. In order to isolate the essential analytic features of the problem from the complicated setting of gravitational collapse in which it arises, some familiarity with conforma

M. I. Wanas

Absolute parallelism geometry is frequently used for physical applications. It has two main defects, from the point of view of applications. The first is the identical vanishing of its curvature tensor. The second is that its autoparallel paths do not represent physical trajectories. The present work shows how these defects were treated in the course of deve

Vladimir Gudkov, Shmuel Nussinov, Zohar Nussinov

A novel approach to complex problems has been previously applied to graph classification and the graph equivalence problem. Here we apply it to the NP complete problem of finding the largest perfect clique within a graph $G$.

D. C. Peets, Ruixing Liang, C. Stock, W. J. L. Buyers

We have grown cubic centimetre-size crystals of YBa2Cu3Ox suitable for neutron studies, by a top-seeded melt-growth technique. Growth conditions were optimized with an eye toward maximizing phase purity. It was found that the addition of 2% Y2BaCuO5 and 0.5% Pt (by mass) were required to prevent melt loss and to obtain the highest crystallinity. A neutron di

Masaki Oshikawa

I reexamine the Nayak&#39;s criticism [Phys. Rev. Lett. 85, 178 (2000); 86, 943 (2001).] on the U(1) gauge theory approach to the strongly correlated systems. Contrary to his conclusion, the arbitrariness of the charge assignment observed by him does not contradict the possibility of a deconfinement. Should the deconfinement occur, the deconfined slave parti

S. T. Bramwell, K. Christensen, J. -Y. Fortin, P. C. W. Holdsworth

Reply to the comment, cond-mat/0209398 by by N.W. Watkins, S.C. Chapman, and G. Rowlands

Xiaobo Nie, Eli Ben-Naim, Shiyi Chen

We study dynamics of freely cooling granular gases in two-dimensions using large-scale molecular dynamics simulations. We find that for dilute systems the typical kinetic energy decays algebraically with time, E(t) ~ t^{-1}, in the long time limit. Asymptotically, velocity statistics are characterized by a universal Gaussian distribution, in contrast with th

Anders M. N. Niklasson, John M. Wills, Mikhail I. Katsnelson, Igor A. Abrikosov

A first-principles disordered local moment (DLM) picture within the local-spin-density and coherent potential approximations (LSDA+CPA) of the actinides is presented. The parameter free theory gives an accurate description of bond lengths and bulk modulus. The case of $δ$-Pu is studied in particular and the calculated density of states is compared to data fr

S. Mazumdar, R. T. Clay, D. K. Campbell

Charge and spin-orderings in the 1/4-filled organic CT solids are of strong interest, especially in view of their possible relations to organic superconductivity. We show that the charge order (CO) in both 1D and 2D CT solids is of the ...1100... type, in contradiction to mean field prediction of >...1010... CO. We present detailed computations for metal-ins

E. E. Kaul, H. Rosner, V. Yushankhai, J. Sichelschmidt

The magnetic behaviour of the low-dimensional Vanadium-oxides Sr2V3O9 and Ba2V3O9 was investigated by means of magnetic susceptibility and specific heat measurements. In both compounds, the results can be very well described by an S=1/2 Heisenberg antiferromagnetic chain with an intrachain exchange of J = 82 K and J = 94 K in Sr2V3O9 and Ba2V3O9, respectivel

Kathia M. Fehsenfeld, Ronald Dickman, Americo T. Bernardes

A bit-string model for the evolution of a population of haploid organisms, subject to competition, reproduction with mutation and selection is studied, using mean field theory and Monte Carlo simulations. We show that, depending on environmental flexibility and genetic variability, the model exhibits a phase transtion between extinction and survival. The mea

E. M. Dizhur, A. N. Voronovsky, I. N. Kotel&#39;nikov, S. E. Dizhur

We present the concept and the results of pilot measurements of tunneling in a system {Al/$δ_{Si}$-GaAs} under pressure up to 2 GPa at 4.2 K. The obtained results may indicate the following: the barrier height for {Al/$δ$-GaAs} equals to 0.86 eV at P=0 and its pressure coefficient is $3 meV/kbar$; charged impurity density in the delta-layer starts to drop fr

Stefan Wessel, Anuradha Jagannathan, Stephan Haas

The antiferromagnetic Heisenberg model is studied on a two-dimensional bipartite quasiperiodic lattice. The distribution of local staggered magnetic moments is determined on finite square approximants with up to 1393 sites, using the Stochastic Series Expansion Quantum Monte Carlo method. A non-trivial inhomogeneous ground state is found. For a given local c

V. N. Narozhnyi, D. Eckert, G. Fuchs, V. Nekvasil

Magnetic properties of high-quality Al-free nonsuperconducting GdBa_2Cu_3O_{6+y} single crystals grown by flux method have been studied. The magnetic anisotropy below the Néel temperature T_N~2.3K corresponds to the direction of Gd^{3+} magnetic moments along the tetragonal c-axis. At T < T_N clear indications of spin-flop transitions for H||c have been obse

Wei Chen, Kazuo Hida, B. C. Sanctuary

One dimensional S=1 XXZ chains with uniaxial single-ion-type anisotropy are studied by numerical exact diagonalization of finite size systems. The numerical data are analyzed using conformal field theory, the level spectroscopy, phenomenological renormalization group and finite size scaling method. We thus present the first quantitatively reliable ground sta

K. X. Chen, Z. H. Ning, H. Y. Xu, Z. Qi

The magnetic ac susceptibility of high-temperature superconductors is shown to obey some scaling relations.We try to ananlyse this behavior within the framework of a common nonlinear response function of mixed state.The derived equations for critical current and ac susceptibility (x(T)) agree with the scaling relations of experimental data.

M. Ricker, H. -R. Trebin

Quasicrystals can carry, in addition to the classical phonon displacement field, a phason displacement field, which requires a generalized theory of elasticity. In this paper, the third-order strain invariants (including phason strain) of icosahedral quasicrystals are determined. They are connected with 20 independent third-order elastic constants. By means

C. Ulrich, G. Khaliullin, S. Okamoto, M. Reehuis

Neutron scattering was used to determine the spin structure and the magnon spectrum of the Mott--Hubbard insulator YTiO$_3$. The magnetic structure is complex, comprising substantial G-type and A-type antiferromagnetic components in addition to the predominant ferromagnetic component. The magnon spectrum, on the other hand, is gapless and nearly isotropic. W

N. W. Watkins, S. C. Chapman, G. Rowlands

This is a comment on &#34;Universal Fluctuations in Correlated Systems&#34;, by Bramwell et al, Phys. Rev. Lett., 84, 3744 (2000.

Heinz-Juergen Schmidt, Juergen Schnack

We give two examples where symmetric polynomials play an important role in physics: First, the partition functions of ideal quantum gases are closely related to certain symmetric polynomials, and a part of the corresponding theory has a thermodynamical interpretation. Further, the same symmetric polynomials also occur in Berezin&#39;s theory of quantization

Nicolas Giovambattista, Sergey V. Buldyrev, Francis W. Starr, H. Eugene Stanley

We investigate the spatially heterogeneous dynamics in the SPC/E model of water by using molecular dynamics simulations. We relate the average mass $n^*$ of mobile particle clusters to the diffusion constant and the configurational entropy. Hence, $n^*$ can be interpreted as the mass of the ``cooperatively rearranging regions&#39;&#39; that form the basis of

Ludovic Berthier

The rheological behavior of soft glassy materials basically results from the interplay between shearing forces and an intrinsic slow dynamics. This competition can be described by a microscopic theory, which can be viewed as a nonequilibrium schematic mode-coupling theory. This statistical mechanics approach to rheology results in a series of detailed theore

Z. Hossain, L. C. Gupta, C. Geibel

Our resistivity, magnetoresistance, magnetization and specific heat data provide unambiguous evidence that CeRhSn2 is a Kondo lattice system which undergoes magnetic transition below 4 K.

Bambi Hu, Jian-Yang Zhu

In this study, we examine the dynamics of a one-dimensional Frenkel-Kontorova chain consisting of nanosize clusters (the &#39;&#39;particles&#39;&#39;) and photochromic molecules (the &#39;&#39;bonds&#39;&#39;), and being subjected to a periodic substrate potential. Whether the whole chain should be running or be locked depends on both the frequency and the

Werner Krauth

I describe the classic circle-packing problem on a sphere, and the analytic and numerical approaches that have been used to study it. I then present a very simple Markov-chain Monte Carlo algorithm, which succeeds in finding the best solutions known today. The behavior of the algorithm is put into the context of the statistical physics of glasses.

Attila Szolnoki

The one-dimensional pair contact process with a particle source is studied by using dynamical cluster mean-field approximations with sites up to $n=12$. The results obtained for different levels of approximation become convergent especially for $n \ge 6$ and allow us to derive reliable extrapolations to the limit $n \to \infty$. At the zero source limit, the

U. Rössler

The equations-of-motion for the density matrix are derived in a multiband model to describe the response of semiconductors (bulk or quantum well structures) under optical excitation with arbitrary polarization. The multiband model used, comprising the twofold conduction band and the fourfold topmost valence band (or heavy- and light-hole states), incorporate

P. Martinez-Samper, J. G. Rodrigo, G. Rubio-Bollinger, H. Suderow

We present extensive Scanning Tunneling Spectroscopy (STM/S) measurements at low temperatures in the multiband superconductor MgB$_2$. We find a similar behavior in single crystalline samples and in single grains, which clearly shows the partial superconducting density of states of both the $π$ and $σ$ bands of this material. The superconducting gaps corresp

S. V. Dmitriev, A. A. Vasiliev, A. E. Miroshnichenko, T. Shigenari

We give a brief review of some generalized continuum theories applied to the crystals with complicated microscopic structure. Three different ways of generalization of the classical elasticity theory are discussed. One is the high-gradient theory, another is the micropolar type theory and the third one is the many-field theory. The importance of the first tw

Alireza Namazi, Nils Eissfeldt, Peter Wagner, Andreas Schadschneider

The Krauss-model is a stochastic model for traffic flow which is continuous in space. For periodic boundary conditions it is well understood and known to display a non-unique flow-density relation (fundamental diagram) for certain densities. In many applications, however, the behaviour under open boundary conditions plays a crucial role.In contrast to all mo

Ansgar Kirchner, Katsuhiro Nishinari, Andreas Schadschneider

We investigate the role of conflicts in pedestrian traffic, i.e. situations where two or more people try to enter the same space. Therefore a recently introduced cellular automaton model for pedestrian dynamics is extended by a friction parameter $μ$. This parameter controls the probability that the movement of all particles involved in a conflict is denied

D. Pal, B. Basu, P. Bandyopadhyay

In the topological framework of high temperature superconductivity we have discussed the Magnus force acting on its vortices.

D. Pal, B. Basu

The topological approach to the understanding of pairing mechanism in high $T_c$ superconductors analyses the relevance of the Berry phase factor in this context. This also gives the evidence for the pairing mechanism to be of magnetic origin.

A. Yu. Cherny

A sum rule has been derived for the static pair correlation function. This rule is the extension of the well-known equation that relates density fluctuation to compressibility. The obtained sum rule is applied to the Bose and Fermi ideal gases as well as BCS and Bogoliubov&#39;s models.

N. Maeda, T. Aoyama, Y. Ishizuka, K. Ishikawa

Neutral collective excitations in the striped Hall state are studied by using the single mode approximation and Hartree-Fock approximation at the half-filled third and fourth Landau level. We find that the spectrum includes anisotropic NG modes and periodic line nodes.

V. P. S. Awana, T. Kawashima, E. Takayama-Muromachi

The Ru0.9Sr2YCu2.1O7.9 sample being synthesized by high-pressure high-temperature solid-state reaction underwent (weak) ferromagnetic transition at 150 K followed by superconducting transition at 30 K. It showed clear Meissner signal in the field-cooled process up to external magnetic field of a few hundred Oe (~300 Oe). The magnetic susceptibility data and

V. P. S. Awana, M. Karppinen, H. Yamauchi, M. Matvejeff

The valence of Ru was analyzed for two RuSr2(Gd0.75Ce0.25)2Cu2O10 samples with different oxygen contents by Ru LIII edge x ray absorption near-edge structure (XANES) spectroscopy. For the sample as-synthesized in 1 atm O2 the DC magnetization data measured in an applied field of 5 Oe showed a clear branching of the zero-field-cooled (ZFC) and field-cooled (F

Andras Suto

We show that in d>1 dimensions the N-particle kinetic energy operator with periodic boundary conditions has symmetric eigenfunctions which vanish at particle encounters, and give a full description of these functions. In two and three dimensions they represent common eigenstates of bosonic Hamiltonians with any kind of contact interactions, and illustrate a

Ashok Razdan

The time evolution of the coherent forward scattering of Synchrotron radiation for resonant nuclei in Brownian motion is studied . Apart from target thickness, the appearance of dynamical beats also depends on $α$ which is the ratio of harmonic force constant to the damping force constant of a harmonic oscillator undergoing Brownian motion.

David Yong, David L. Lambert

The results of a search for cool subdwarfs are presented. Kinematic (U, V, and W) and stellar parameters (Teff, log g, [Fe/H], and V_t) are derived for 134 candidate subdwarfs based on high resolution spectra. The observed stars span 4200K < Teff < 6400K and -2.70 < [Fe/H] < 0.25 including only 8 giants (log g < 4.0). Of the sample, 100 stars have MgH bands

Nino Panagia

We review the expected properties of the first stellar generations in the Universe. In particular, we consider and discuss the diagnostics, based on the emission from associated HII regions, that permit one to discern bona fide primeval stellar generations from the ones formed after pollution by supernova explosions has occurred. We argue that a proper chara

J. Kaluzny, S. M. Rucinski, I. B. Thompson

We present photometric and spectroscopic observations of the optical companion to the millisecond radio pulsar PSR J1740-5340 in the globular cluster NGC 6397. An analysis of the photometric variability in the B, V, and I-bands indicates an inclination of the system of 43.9+-2.1 degrees if the optical companion fills its Roche lobe (a semi-detached configura

W. V. Dixon, T. M. Brown, W. B. Landsman

We have observed the hot post-AGB star ZNG 1 in the globular cluster M5 with the Far Ultraviolet Spectroscopic Explorer (FUSE). From the resulting spectrum, we derive an effective temperature T_eff ~ 45,000 K, a rotational velocity v_rot ~ 100 km/s, carbon and nitrogen abundances approximately ten times solar, a wind with terminal velocity near 1000 km/s, an

J. M. Rankin, R. Ramachandran

The average polarization properties of conal single and double profiles directly reflect the polarization-modal structure of the emission beams which produce them. These average properties require that the circulating subbeam systems which produce conal beams entail paired PPM and SPM emission elements which are offset from each other in both magnetic azimut

C. S. Kochanek

The solution proposed by Zhao & Qin to the apparent conflict between gravitational lens time delays, local estimates of the Hubble constant and current expectations for the structure of CDM halos is discussed. Two essential points emerge. First, the degeneracy is exactly the same as the local surface density degeneracy previously discussed in the literature.

M. Eracleous, J. P. Halpern, J. C. Charlton

We have observed the broad-line radio galaxy Arp 102B with ASCA in order to determine the absorbing column density towards its X-ray source and measure its X-ray spectrum. The ultimate goal was to constrain the properties of the medium responsible for the metastable Fe II absorption lines observed in its UV spectrum. The 0.5-10 keV X-ray spectrum is describe

R. P. Saglia, Claudia Maraston, Daniel Thomas, Ralf Bender

We measure the central values (within Re/8) of the CaII triplet line indices CaT* and CaT and the Paschen index PaT at 8600 AA for a 93%-complete sample of 75 nearby early-type galaxies with BT<12 and Vgal<2490 km/s. We find that the values of CaT* are constant to within 5% over the range of central velocity dispersions 100<sigma<340 km/s, while the PaT (and

Tomasz Bulik, Marek Sikora, Rafal Moderski

As it was recently shown by Derishev etal (1999), initial GRB ejecta are likely to contain comparable number of protons and neutrons. During acceleration process, and/or later, due to interaction with external medium, such ejecta are likely to be split into spatially distinct shells of neutron and proton-electron plasmas. This leads to dynamical effects whic

M. A. Barstow, N. P. Bannister, R. G. Cruddace, M. P. Kowalski

We report on the successful sounding rocket flight of the high resolution (R=3000-4000) J-PEX EUV spectrometer. J-PEX is a novel normal incidence instrument, which combines the focusing and dispersive elements of the spectrometer into a single optical element, a multilayer-coated grating. The high spectral resolution achieved has had to be matched by unprece