November 2000 arXiv papers — page 5

D. Rusin, C. S. Kochanek, M. Norbury, E. E. Falco

HST V and I-band observations show that the gravitational lens B1359+154 consists of six images of a single z_s=3.235 radio source and its star-forming host galaxy, produced by a compact group of galaxies at z_l = 1. VLBA observations at 1.7 GHz strongly support this conclusion, showing six compact cores with similar low-frequency radio spectra. B1359+154 is

Kelly Holley-Bockelmann, J. Christopher Mihos, Steinn Sigurdsson, Lars Hernquist

We construct numerical models of mildly triaxial elliptical galaxies with central density cusps. Using a technique we call ``adiabatic squeezing'', we begin with a spherical gamma=1 Hernquist model and apply a drag to the velocities of the particles along each principle axis. The final models are stable in isolation, preserving their density structur

A. G. Doroshkevich, P. D. Naselsky

In this paper we briefly discuss the problem of the origin of Ultra High Energy Cosmic Rays in the framework of Top-Down models. We show that, for high energy of decays and in a wide range of spectra of injected protons, their extragalactic flux is consistent with the observed fluxes of cosmic rays in the energy range 0.1 E_{GZK}< E < 10E_{GZK}. For suitable

J. S. Sa&#39; Martins, S. Moss de Oliveira, G. A. de Medeiros

We introduce a multi-locus genetically acquired phenotype, submitted to mutations and with selective value, in an age-structured model for biological aging. This phenotype describes a single-trait effect of the environment on an individual, and we study the resulting distribution of this trait among the population. In particular, our simulations show that th

Krishna Rajagopal, Frank Wilczek

Important progress in understanding the behavior of hadronic matter at high density has been achieved recently, by adapting the techniques of condensed matter theory. At asymptotic densities, the combination of asymptotic freedom and BCS theory make a rigorous analysis possible. New phases of matter with remarkable properties are predicted. They provide a th

David P. Bennett, Sun Hong Rhie

We show that a space-based gravitational microlensing survey for terrestrial extra-solar planets is feasible in the near future, and could provide a nearly complete picture of the properties of planetary systems in our Galaxy. We present simulations of such a survey using a 1-2m aperture space telescope with a ~2 square degree field-of-view which is used to

David J. Lin, R. Misra, Ronald E. Taam

Hydrodynamical winds from a spherical two-temperature plasma surrounding a compact object are constructed. The mass-loss rate is computed as a function of electron temperature, optical depth and luminosity of the sphere, the values of which can be constrained by the fitting of the spectral energy distributions for known X-ray binary systems. The sensitive de

Prakash Mathews

We study the Compton scattering in the noncommutative counter part of QED (NC QED). Interactions in NC QED have momentum dependent phase factors and the gauge fields have Yang Mills type couplings, this modifies the cross sections and are different from the commuting Standard Model. Collider signals of noncommutative space-time are studied at the Next Linear

Jesper Lykke Jacobsen, Jesús Salas

We study the chromatic polynomials for m \times n square-lattice strips, of width 9 <= m <= 13 (with periodic boundary conditions) and arbitrary length n (with free boundary conditions). We have used a transfer matrix approach that allowed us also to extract the limiting curves when n \to \infty. In this limit we have also obtained the isolated limiting poin

Chong-Sun Chu, Brian R. Greene, Gary Shiu

We briefly discuss some possible cosmological implications of noncommutative geometry. While the noncommutativity we consider does not affect gravity, it can play an important role in the dynamics of other fields that are present in the early universe. We point out the possibility that noncommutativity may cause inflation induced fluctuations to become non-g

M. J. Davis, S. A. Morgan, K. Burnett

We introduce a time-dependent projected Gross-Pitaevskii equation to describe a partially condensed homogeneous Bose gas, and find that this equation will evolve randomised initial wave functions to equilibrium. We compare our numerical data to the predictions of a gapless, second order theory of Bose-Einstein condensation [S. A. Morgan, J. Phys. B {\bf 33},

J. S. Sanders, A. C. Fabian

We present a simple method for adaptively binning the pixels in an image. The algorithm groups pixels into bins of size such that the fractional error on the photon count in a bin is less than or equal to a threshold value, and the size of the bin is as small as possible. The process is particularly useful for generating surface brightness and colour maps, w

Saharon Shelah

We deal with stability theory for ``reasonable&#39;&#39; non-elementary classes without any remanents of compactness (like: above Hanf number or definable by L_{omega_1, omega}).

John Ellis

On his way home from Troy, Odysseus had arrived within reach of Ithaca when a great storm blew up. He was swept away, and only several years later was he able to return to reclaim his rights from the rapacious suitors, with the aid of his son Telemachus. Some wonder whether this epic is repeating itself, if the Higgs weighs 115 GeV. If so, are CMS and ATLAS

Sudeshna DasGupta, Pinku Chattopadhyay, Soumen Kumar Roy

The effect of a rigid nonpolar non-mesogenic solute, ``biphenyl&#39;&#39; which is (C_{6}H_{5}-C_{6}H_{5}), on the splay and bend elastic constants and on the rotational viscosity coefficient of (4,4^{\prime})-n-octyl-cyano biphenyl (8CB) is reported. The experiments involve the measurement of voltage dependence of capacitance of a cell filled with the mixtu

P. Philippe, D. Bideau

A simple numerical model is used to simulate the effect of vertical taps on a packing of monodisperse hard spheres. Our results are in agreement with an experimantal work done in Chicago and with other previous models, especially concerning the dynamics of the compaction, the influence of the excitation strength on the compaction efficiency, and some ageing

M. D. Scadron, D. Tadić

We first review the current algebra - PCAC approach to nonleptonic octet baryon 14 weak decay B (\to) (B^{\prime})(π) amplitudes. The needed four parameters are independently determined by (Ω\to Ξπ),(ΛK) and (Ξ^{-}\to Σ^{-}γ) weak decays in dispersion theory tree order. We also summarize the recent chiral perturbation theory (ChPT) version of the eight indep

S. M. Oliveira, L. Bruecher, R. Santos, A. Barroso

We have calculated the one-loop electroweak corrections to the decay t-> bW+, including the counterterm for the CKM matrix elements V(tb). Previous calculations used an incorrect delta V(tb) that led to a gauge dependent amplitude. However, since the contribution stemming from delta V(tb) is small, those calculations only underestimate the width by roughly o

M. K. Volkov, V. L. Yudichev

An effective meson Lagrangian including a scalar glueball is constructed on the base of $U(3)\times U(3)$ chiral symmetry. The glueball is introduced into the meson Lagrangian by using the principle of scale invariance of an effective Lagrangian and the dilaton model. The singlet-octet mixing of scalar meson states is described by means of &#39;t Hooft inter

Jose&#39; P. S. Lemos

We review the toroidal, cylindrical and planar black hole solutions in anti-de Sitter spacetimes and present their properties.

Martin Weigt, Alexander K. Hartmann

The minimal vertex-cover (or maximal independent-set) problem is studied on random graphs of finite connectivity. Analytical results are obtained by a mapping to a lattice gas of hard spheres of (chemical) radius one, and they are found to be in excellent agreement with numerical simulations. We give a detailed description of the replica-symmetric phase, inc

Armin Uhlmann

The entropy H_T(rho) of a state rho with respect to a channel T and the Holevo capacity of the channel require the solution of difficult variational problems. For a class of 1-qubit channels, which contains all the extremal ones, the problem can be significantly simplified by associating an Hermitian antilinear operator theta to every channel of the consider

Saurabh D. Rindani

Order-alpha_s QCD corrections in the soft-gluon approximation to angular distributions of decay charged leptons in the process e+e- -> t tbar, followed by semileptonic decay of t or tbar, are obtained in the e+e- centre-of-mass frame. As compared to distributions in the top rest frame, these have the advantage that they would allow direct comparison with exp

Indranil Mitra, Shibaji Roy

Starting from the (q,p) 5-brane solution of type IIB string theory, we here construct the low energy configuration corresponding to (NS5,Dp)-brane bound states (for $0\leq p\leq 4$) using the T-duality map between type IIB and type IIA string theories. We use the SL(2,Z) symmetry on the type IIB bound state (NS5,D3) to construct (NS5,D5,D3) bound state. We t

Jose Maria Ancochea, Otto Rutwig Campoamor

By using the concept of weight graph associated to certain nilpotent Lie algebras $\frak{g}$, we find necessary and sufficient conditions for a semidirect product $\frak{g}\oplus T_{i}$, where $T_{i}<T$ is a subalgebra of a maximal torus of derivations $T$ of $\frak{g}$ which induces a decomposition of $\frak{g}$ into one dimensional weight spaces, to be 2-s

Kenji Tomita

Corresponding to the recent observational claims that we are in a local void (an underdense region) on scales of 200 - 300 Mpc, the magnitude-redshift relation in a cosmological model with a local void is investigated. It is already evident that the accelerating behavior of high-z supernovae can be explained in this model, because the local void plays a role

Ivan Smith

We study Lefschetz pencils on symplectic four-manifolds via the associated spheres in the moduli spaces of curves, and in particular their intersections with certain natural divisors. An invariant defined from such intersection numbers can distinguish manifolds with torsion first Chern class. We prove that pencils of large degree always give spheres which be

Bosiljka Tadic

We introduce and simulate a growth model of the world-wide Web based on the dynamics of outgoing links that is motivated by the conduct of the agents in the real Web to update outgoing links (re)directing them towards constantly changing selected nodes. Emergent statistical correlation between the distributions of outgoing and incoming links is a key feature

Youngjai Kiem, Dong Hyun Park, Sangmin Lee

The generalized *-products, or the $*_N$-products, appear both in the one-loop effective action of noncommutative Yang-Mills theories and in the coupling of a closed string to N open strings on a disk when the D-brane world-volume is noncommutative. Factorization of the string amplitudes provides a uniform understanding of the $*_N$-products and a hint to ob

Duncan H. J. O&#39;Dell

Eigenvalues and eigenfunctions of Mathieu&#39;s equation are found in the short wavelength limit using a uniform approximation (method of comparison with a `known&#39; equation having the same classical turning point structure) applied in Fourier space. The uniform approximation used here relies upon the fact that by passing into Fourier space the Mathieu eq

R. H. Dalitz, G. Garbarino

The predictions of local realistic theories for the observables concerning the evolution of a $K^0\bar{K}^0$ quantum entangled pair (created in the decay of the $ϕ$-meson) are discussed. It is shown, in agreement with Bell&#39;s theorem, that the most general local hidden-variable model fails in reproducing the whole set of quantum-mechanical joint probabili

F. Floegel, L. Santos, M. Lewenstein

We study the optical loading of a trapped Bose-Einstein condensate by spontaneous emission of atoms in excited electronic state in the Boson-Accumulation Regime. We generalize the previous simplified analysis of ref. [Phys. Rev. A 53, 2466 (1996)], to a 3D case in which more than one trap level of the excited state trap is considered. By solving the correspo

Abhijat Vichare, D. G. Kanhere, S. A. Blundell

We study the thermodynamics of Na_8 and Na_{20} clusters using multiple-histogram methods and an ab initio treatment of the valence electrons within density functional theory. We consider the influence of various electron kinetic-energy functionals and pseudopotentials on the canonical ionic specific heats. The results for all models we consider show qualita

D. Almehed, S. Frauendorf, F. Do&#34;nau

The tilted axis cranking model is used in combination with the random phase approximation and particle number projection to analyze the influence of dynamical pair correlations in the high-K bands of 178-W and their effect on relative energy and angular momentum. The calculations show the importance of dynamical pair correlations to describe the experiment a

B. Kampfer, K. Gallmeister, O. P. Pavlenko

The evolution of strongly interacting matter during the cosmological confinement transition is reviewed. Despite of many proposed relics no specific signal from the rearrangement of quarks and gluons into hadrons has been identified by observations. In contrast to this, several observables in heavy-ion collisions at CERN-SPS energies point to the creation of

Tetsufumi Hirano, Keiichi Tsuda, Kohei Kajimoto

We analyze non-central heavy-ion collisions at the relativistic energy within a full (3+1) dimensional hydrodynamic model. First, the initial parameters in the hydrodynamic model are chosen so that we reproduce the experimental data of both the rapidity distribution and the slope of transverse mass distribution in central Pb + Pb collisions at 158 $A$ GeV at

G. Sparano, G. Vilasi

Geometric structures underlying commutative and non commutative integrable dynamics are analyzed. They lead to a new characterization of noncommutative integrability in terms of spectral properties and of Nijenhuis torsion of an invariant (1,1) tensor field. The construction of compatible symplectic structures is also discussed.

P. Gualtieri, C. M Casciola, R. Benzi, G. Amati

In this paper we discuss the dynamical features of intermittent fluctuations in homogeneous shear flow turbulence. In this flow the energy cascade is strongly modified by the production of turbulent kinetic energy related to the presence of vortical structures induced by the shear. By using direct numerical simulations, we show that the refined Kolmogorov si

Detlev Buchholz

Algebraic quantum field theory is an approach to relativistic quantum physics, notably the theory of elementary particles, which complements other modern developments in this field. It is particularly powerful for structural analysis but has also proven to be useful in the rigorous treatment of models. In this contribution a non-technical survey is given wit

Jozsef Lorinczi, Robert A. Minlos, Herbert Spohn

We prove that Nelson&#39;s massless scalar field model is infrared divergent in three dimensions. In particular, the Nelson Hamiltonian and the Hamiltonian obtained from Euclidean quantization are not unitarily equivalent. In contrast, for dimensions higher than three the Nelson Hamiltonian has a unique ground state in Fock space and the two Hamiltonians are

Richard Kenyon

We compute the asymptotic determinant of the discrete Laplacian on a simply-connected rectilinear region in R^2. As an application of this result, we prove that the growth exponent of the loop-erased random walk in Z^2 is 5/4.

Anatol N. Kirillov

We report about results revolving around Kostka-Foulkes and parabolic Kostka polynomials and their connections with Representation Theory and Combinatorics. It appears that the set of all parabolic Kostka polynomials forms a semigroup, which we call {\it Liskova semigroup}. We show that polynomials frequently appearing in Representation Theory and Combinator

Chandrashekhar Khare

We prove that the reduction mod \ell of the local Langlands correspondence between supercuspidal representations of GL_n(F), where F is a finite extension of Q_p, and representations of the Galois group of F is well-defined. The results and methods of this paper have been used by Vigneras to give a proof of the ``local Langlands conjecture mod \ell&#39;&#39;

Chandrashekhar Khare, C. S. Rajan

We prove that the density of ramified primes in semisimple p-adic representations of Galois groups of number fields is 0. Ravi Ramakrishna has produced examples of such representations that are infinitely ramified.

Katsuya Eda, Saharon Shelah

An infinitary version of the notion of free products has been introduced and investigated by G.Higman. Let G_i (for i in I) be groups and ast_{i in X} G_i the free product of G_i (i in X) for X Subset I and p_{XY}: ast_{i in Y} G_{i}->ast_{i in X} G_{i} the canonical homomorphism for X subseteq Y Subset I. (X Subset I denotes that X is a finite subset of I.)

Paul C. Eklof, Saharon Shelah

We consider the Whitehead problem for principal ideal domains of large size. It is proved, in ZFC, that some p.i.d.&#39;s of size >= aleph_{2} have non-free Whitehead modules even though they are not complete discrete valuation rings.

Paul C. Eklof, Saharon Shelah

It is proved undecidable in ZFC + GCH whether every Z-module has a^{perp} {Z}-precover.

Sergey Finashin

A non-singular connected algebraic curve $A$ in a simply connected algebraic surface $X$ can be knotted so that its homology class and the fundamental group of its complement in $X$ is preserved, provided $A$ is sufficiently complex (not too ``rigid&#39;&#39;). For example, it is true if $A$ admits a degeneration to an irreducible curve $A_0$ having a unique

Tien-Cuong Dinh

Let f be a polynomial endomorphism of degree d>1 of C^k (k>1) which extends to a holomorphic endomorphism of P^k. Assume that the maximal order Julia set of f is laminated by real hypersurfaces in some open set. We show that f is homogenous and is a polynomial lift of a Lattes endomorphism of P^{k-1}.

Jose Maria Ancochea, Otto Rutwig Campoamor

We review the known results about characteristically nilpotent complex Lie algebras, as well as we comment recent developements in the theory.

Ivan Smith

Symplectic four-manifolds give rise to Lefschetz fibrations, which are determined by monodromy representations of free groups in mapping class groups. We study the topology of Lefschetz fibrations by analysing the action of the monodromy on the universal cover of a smooth fibre. We give new and simple proofs that Lefschetz fibrations arising from pencils (i.

S. Ole Warnaar

Given an arbitrary ordered pair of coprime integers (a,b) we obtain a pair of identities of the Rogers--Ramanujan type. These identities have the same product side as the (first) Andrews--Gordon identity for modulus 2ab\pm 1, but an altogether different sum side, based on the representation of (a/b-1)^{\pm 1} as a continued fraction. Our proof, which relies

Yujiro Kawamata

We consider Fujita&#39;s freeness conjecture in a relative setting and prove a criterion by proving a correct Q-divisor version of the Kollar vanishing theorem.

Tom Roby, Frank Sottile, Jeffrey Stroomer, Julian West

We study four operations defined on pairs of tableaux. Algorithms for the first three involve the familiar procedures of jeu de taquin, row insertion, and column insertion. The fourth operation, hopscotch, is new, although specialised versions have appeared previously. Like the other three operations, this new operation may be computed with a set of local ru

Harold Blas

A submodel of the so-called conformal affine Toda model coupled to the matter field (CATM) is defined such that its real Lagrangian has a positive-definite kinetic term for the Toda field and a usual kinetic term for the (Dirac) spinor field. After spontaneously broken the conformal symmetry by means of BRST analysis, we end up with an effective theory, the

Cesar Gomez, Bert Janssen, Pedro J. Silva

A stable non-commutative solution with symmetry breaking is presented for a system of Dp-branes in the presence of a RR (p+5)-form.

Thomas Strobl

In this habilitation thesis we provide an introduction to gravitational models in two spacetime dimensions. Focus is put on exactly solvable models. We begin by introducing and motivating different possible gravitational actions, including those of generalized dilaton theories as well as of purely geometrical, higher derivative theories with and without tors

Bernard de Wit, Hermann Nicolai

In this review we discuss hidden symmetries of toroidal compactifications of eleven-dimensional supergravity. We recall alternative versions of this theory which exhibit traces of the hidden symmetries when still retaining the massive Kaluza-Klein states. We reconsider them in the broader perspective of M-theory which incorporates a more extended variety of

Martin Schnabl

Using anomalous symmetries of the cubic string field theory vertex we derive set of relations between the coefficients of the tachyon condensate. They are in agreement with the results obtained from level truncation approximation.

B. P. Kosyakov

A plausible physical interpretation of the renormalizability condition is given. It is shown that renormalizable quantum field theories describe such systems wherein the tendency to collapse associated with vacuum fluctuations of attractive forces is suppressed by vacuum fluctuations of kinetic energy. Relaying on the classification of topological types of e

Jose&#39; P. S. Lemos

We study the supersymmetry of the charged rotating toroidal black hole solutions found by Lemos and Zanchin, and show that the only configurations that are supersymmetric are: (i) the non-rotating electrically charged naked singularities already studied by Caldarelli and Klemm, and (ii) an extreme rotating toroidal black hole with zero magnetic and electric

Christian Schubert

A survey is given of applications of the ``string-inspired&#39;&#39; worldline formalism to the computation of amplitudes and effective actions in QED.

S. Khalil

We study the inclusive branching ratio for B-> X_s gamma in a class of string-inspired SUSY models with non-universal soft-breaking A-terms. We show that b->s gamma do not severely constrain the non-universality of these models and the parameter regions which are important for generating sizeable contribution to epsilon&#39;/epsilon, of order 2 x10^(-3), are

S. Khalil

We study the predictions for the direct CP violation parameter epsilon&#39;/epsilon in a class of string-inspired model with non-universal soft A-terms. We show that the non-universality of the A-terms plays an important rule in enhancing the supersymmetric contributions to the CP violation epsilon&#39;/epsilon. In particular, the supersymmetric contribution

She-Sheng Xue

We present and study a possible mechanism of extracting energies from the vacuum by external classical fields. Taking a constant magnetic field as an example, we discuss why and how the vacuum energy can be released in the context of quantum field theories. In addition, we give a theoretical computation showing how much vacuum energies can be released. The p

Robert Fleischer

After an introduction to the Standard-Model description of CP violation and a brief look at the present status of this phenomenon in the kaon system, a classification of non-leptonic B-decays is given and the formalism of $B^0_{d,s}$--$\bar{B^0_{d,s}}$ mixing is discussed. We then turn to the $B$-factory benchmark modes, CP violation in charged B decays, and

F. Becattini, J. Cleymans, A. Keranen, E. Suhonen

Results of a systematic study of fully integrated particle multiplicities in central Au-Au and Pb-Pb collisions at beam momenta 1.7 A GeV, 11.6 A GeV (Au-Au) and 158 A GeV (Pb-Pb) using a statistical-thermal model are presented. The close similarity of the colliding systems makes it possible to study heavy ion collisions under definite initial conditions ove

T. Csorgo

The basics and the formalism of Bose-Einstein correlations is briefly reviewed. The invariant Buda-Lund form is summarized. Tools are presented that can be utilized in a model-independent search for non-Gaussian structuctures in the two-particle Bose-Einstein correlation functions. The binary source formalism of particle interferometry is presented and relat

V. A. Khoze, A. D. Martin, M. G. Ryskin

We briefly describe a model for soft diffraction. The model description of ISR, SppbarS and Tevatron data, and the predictions of the total, elastic, single and double diffractive cross sections at the LHC can be found in the original paper. Here we address issues raised at Diffraction 2000, in particular concerning the nature of the resulting Pomeron trajec

I. G. Irastorza, A. Morales, C. E. Aalseth, F. T. Avignone

Two germanium detectors are currently operating in the Canfranc Underground Laboratory at 2450 m.w.e looking for WIMP dark matter. One is a 2 kg 76Ge IGEX detector (RG-2) which has an energy threshold of 4 keV and a low-energy background rate of about 0.3 c/keV/kg/day. The other is a small (234 g) natural abundance Ge detector (COSME), of low energy threshol

Xiao-Gang He, Changhao Jin, J. P. Ma

The effects of initial $b$ quark bound state for the semi-inclusive decays $B\to K(K^*) X$ are studied using light cone expansion and heavy quark effective theory methods. We find that the initial bound state effects on the branching ratios and CP asymmetries are small. In the light cone expansion approach, the CP-averaged branching ratios are increased by a

Riccardo Barbieri, Alessandro Strumia

Is there a Higgs? Where is it? Is supersymmetry there? Where is it? By discussing these questions, we call attention to the `LEP paradox&#39;, which is how we see the naturalness problem of the Fermi scale after a decade of electroweak precision measurements, mostly done at LEP.

S. Fortunato, F. Karsch, P. Petreczky, H. Satz

Effective theories are helpful tools to gain an intuitive insight into phenomena governed by complex laws. In this work we show by means of Monte Carlo simulations that Z(2) spin models with only spin-spin interactions approximate rather well the critical behavior of SU(2) gauge theory at finite temperature. These models are then used to formulate an effecti

Massimo Di Pierro

Matrix Distributed Processing is a collection of classes and functions written in C++ for fast development of efficient parallel algorithms for the most general lattice/grid application. FermiQCD is an Object Oriented Lattice QCD application of MDP, under development at Fermilab.

Z. Burda, Pawel Sawicki

We discuss a new numerical method for the determination of excited states of a quantum system using a generalization of the Feynman-Kac formula. The method relies on introducing an ensemble of non-interacting identical systems with a fermionic statistics imposed on the systems as a whole, and on determining the ground state of this fermionic ensemble by taki

Stefan Sint

I review the strategies which have been developped in recent years to solve the non-perturbative renormalization problem in lattice field theories. Although the techniques are general, the focus will be on applications to lattice QCD. I discuss the momentum subtraction and finite volume schemes, and their application to scale dependent renormalizations. The

Lucien Cremaldi

Standard model mixing and CP violation are expected to be small in the charm sector. Some argue that only in the presence of new physics do we currently expect to observe these effects. Fermilab experiment E791 has the largest sample of reconstructed charm decays recorded to date. We have made an exhaustive search for D0 D0-bar mixing and CP violation in thi

L3 Collaboration

A search for chargino, neutralino and scalar lepton pair-production in e+e- collisions at the centre-of-mass energy of 189 GeV is performed under the assumptions that R-parity is not conserved in decays and only one of the coupling constants lambda_ijk, lambda&#39;_ijk or lambda&#39;&#39;_ijk is non-negligible. No signal is found in a data sample correspondi

Marco Battaglia, Daniel Schulte

The effect of the overlap of gamma gamma -> hadrons to H nu nu events has been studied for the case of the Tesla e+e- linear collider at 350 GeV. It was found that, due to the significant bunch length and the track extrapolation accuracy provided by the Vertex Tracker, the gamma gamma background to physics events can be substantially reduced, with moderate l

K. Huttmann

The lifetimed of the Bbar0 and B- meson lifetimes are measured using data recorded on the Z peak with the ALEPH detector at LEP. An improved analysis based on partially reconstructed Bbar0 -> D*+l-nubar and B- -> D0l-nubar decays is presented.

Hwanbae Park

Measurement results on $D^0$-$\bar D^0$ mixing and CP violation are presented. FOCUS, a fixed target experiment at Fermilab, collected a high statistics photo-produced charm sample collected during the 96-97 run. We reconstructed more than 1 million charmed particles and compared the lifetimes of two $D^0$ meson decays to $K^-π^+$ and $K^-K^+$. The mixing pa

Marco Cavaglia, Paulo Vargas Moniz

We present the canonical and quantum cosmological investigation of a four-dimensional, spatially flat, Friedmann-Robertson-Walker (FRW) model that is derived from the bosonic Neveu-Schwarz/Neveu-Schwarz sector of the low-energy M-theory effective action. We discuss in detail the phase space of the classical theory. We find the quantum solutions of the model

Luis A. Anchordoqui, S. Capozziello, G. Lambiase, Diego F. Torres

Using traversable wormholes as theoretical background, we revisit a deep question of general relativity: Does a uniformly accelerated charged particle radiate? We particularize to the recently proposed gravitational Čerenkov radiation, that happens when the spatial part of the Ricci tensor is negative. If $^{^{(3+1)}}R^i_{\phantom{i}i}< 0$, the matter thread

F. Siebel, J. A. Font, E. Mueller, P. Papadopoulos

We present tests and results of a new axisymmetric, fully general relativistic code capable of solving the coupled Einstein-matter system for a perfect fluid matter field. Our implementation is based on the Bondi metric, by which the spacetime is foliated with a family of outgoing light cones. We use high-resolution shock-capturing schemes to solve the fluid

Hiromi Saida, Jiro Soda

The classical central charge for the higher curvature gravity in 3-dimensions is calculated using the Legendre transformation method. The statistical entropy of BTZ black hole is derived by the Cardy&#39;s formula and the result completely coincides with the Iyer-Wald formula for the geometrical entropy. This coincidence suggests the generalized AdS/CFT corr

David B. Malament

Within the framework of general relativity, in some cases at least, it is a delicate and interesting question just what it means to say that an extended body is or is not &#34;rotating&#34;. It is so for two reasons. First, one can easily think of different criteria of rotation. Though they agree if the background spacetime structure is sufficiently simple,

Hudson Turner

Some normal logic programs under the answer set (stable model) semantics lack the appealing property of &#34;cautious monotonicity.&#34; That is, augmenting a program with one of its consequences may cause it to lose another of its consequences. The syntactic condition of &#34;order-consistency&#34; was shown by Fages to guarantee existence of an answer set.

Sara Cohen, Yaron Kanza, Yakov Kogan, Werner Nutt

EquiX is a search language for XML that combines the power of querying with the simplicity of searching. Requirements for such languages are discussed and it is shown that EquiX meets the necessary criteria. Both a graphical abstract syntax and a formal concrete syntax are presented for EquiX queries. In addition, the semantics is defined and an evaluation a

B. N. Narozhny, I. L. Aleiner, Ady Stern

We consider mesoscopic fluctuations of Coulomb drag transresistivity between two layers at a Landau level filling factor $ν=1/2$ each. We find that at low temperature sample to sample fluctuations exceed both the ensemble average and the corresponding fluctuations at B=0. At the experimentally relevant temperatures, the variance of the transresistivity is pr

M. H. S. Amin

Two different aspects of high T_c superconductivity is studied in two independent parts of this thesis. In the first part we study Landau&#39;s Fermi liquid theory and nearly antiferromagnetic Fermi liquid theory (NAFL) in 2D. We that inflection points on the Fermi surface provide 2D singularities which have to be taken seriously in Fermi liquid consideratio

Ian Affleck, Masaki Oshikawa, Hubert Saleur

SU(3)-invariant &#34;spin&#34; chains with a single impurity, such as a modified exchange coupling on one link, are analyzed using boundary conformal field theory techniques. These chains are equivalent to a special case of the &#34;tJV&#34; model, i.e. the t-J model with a nearest neighbour repulsion added. In the continuum limit they are equivalent to two

V. Barzykin

We consider the low-temperature behavior of NMR relaxation rates $T_1$ and $T_{2G}$ in the spin-1/2 antiferromagnetic chain. We find that $T_1 \propto const$ and $T_{2G} \propto \sqrt{T}$, with logarithmic corrections. We determine both constants and logarithmic terms by matching perturbative RG with exact results, so that the final expressions for the relax

Z. Burda, R. A. Janik, J. Jurkiewicz, M. A. Nowak

Using the theory of free random variables (FRV) and the Coulomb gas analogy, we construct stable random matrix ensembles that are random matrix generalizations of the classical one-dimensional stable Lévy distributions. We show that the resolvents for the corresponding matrices obey transcendental equations in the large size limit. We solve these equations i

Sven P. Rudin, Amy Y. Liu, J. K. Freericks, A. Quandt

Density-functional calculations are presented for high-pressure structural phases of S and Se. The structural phase diagrams, phonon spectra, electron-phonon coupling, and superconducting properties of the isovalent elements are compared. We find that with increasing pressure, Se adopts a sequence of ever more closely packed structures (beta-Po, bcc, fcc), w

F. Ganazzoli, Yu. A. Kuznetsov, E. G. Timoshenko

We study conformations assumed by single diblock star copolymers in a poor solvent by means of the Gaussian variational theory and Monte Carlo simulation in continuous space. Cases of stars with internal and external hydrophobic blocks are analysed. While in the former case the collapsed state has an obvious micellar shape, the latter case exhibits two nontr

Miguel A. Munoz, Ronald Dickman, Romualdo Pastor-Satorras, Alessandro Vespignani

We review some recent results on the relations between sandpiles and a class of absorbing state phase transitions. We use the concept of fixed energy sandpiles (FES), in which external driving and dissipation are absent. FES are shown to exhibit an absorbing state transition with critical properties coinciding with those of the corresponding sandpile model.

S. M. Badalyan, F. M. Peeters

The spectrum of magnetic edge states and their transport properties in the presence of a perpendicular non-homogeneous magnetic field in a quantum wire formed by a parabolic confining potential are obtained. Systems are studied where the magnetic field exhibits a discontinuous jump in the transverse direction and changes its sign, strength, and both sign and

S. Dumitru, A. Boer

The work approaches the study of the fluctuations for the thermodynamic systems in the presence of the fields. The approach is of phenomenological nature and developed in a Gaussian approximation. The study is exemplified on the cases of a magnetizable continuum in a magnetoquasistatic field, as well as for the so called discrete systems. In the last case on

A. Pandey, Dipten Bhattacharya, R. G. Sharma

Relaxation of the intergranular critical state has been observed at a very low applied magnetic field (10-50 Oe) over a temperature regime of 20-77 K in bulk polycrystalline YBa(2)Cu(3)O(7-x) (YBCO) and Bi(1.75)Pb(0.35)Sr(2)Ca(2)Cu(3)O(10+x) (BPSCCO) samples. In such a disordered Josephson junction network, the relaxation is slower than the intragranular rel

Ming-Che Chang, Min-Fong Yang

The effect of a one-dimensional periodic electrostatic modulation on quantum Hall systems with filling factor ν=1 is studied. We propose that, either when the amplitude of the modulation potential or the tilt angle of the magnetic field is varied, the system can undergo a first-order phase transition from a fully spin-polarized homogeneous state to a partial