November 1999 arXiv papers — page 26

D. R. Lorimer, R. Ramachandran

The fact that the majority of the youngest radio pulsars are surrounded by expanding supernova remnants is strong evidence that neutron stars are produced in the supernovae of massive stars. In many cases, the pulsar appears significantly offset from the geometric centre of the supernova remnant, indicating that the neutron star has moved away from the site

Patricia B. Tissera

The star formation rate history of galactic objects in hydrodynamical cosmological simulations are analyzed in relation to their merger histories. The findings suggest that massive mergers produce more efficient starbursts and that, depending on the internal structure of the objects, double starbursts could also occur.

Dipak Munshi, Peter Coles

We investigate the effect of weak gravitational lensing in the limit of small angular scales where projected galaxy clustering is strongly nonlinear. This is the regime likely to be probed by future weak lensing surveys. We use well-motivated hierarchical scaling arguments and the plane-parallel approximation to study multi-point statistical properties of th

Sarbani Basu, H. M. Antia

Most helioseismic analyses are based on solar oscillations frequencies obtained by fitting symmetric peak profiles to the power spectra. However, it has now been demonstrated that the peaks are not symmetric. In this work we study the effects of asymmetry of the peak profiles on the solar oscillations frequencies of p-modes for low and intermediate degrees.

G. Stasinska, R. Szczerba

We have performed a statistical analysis using broad band IRAS data on about 500 planetary nebulae with the aim of characterizing their dust content. Our approach is different from previous studies in that it uses an extensive grid of photoionization models to test the methods for deriving the dust temperature, the dust-to-gas mass ratio and the average grai

F. R. Querci, M. Querci

Nowadays many telescopes around the world are automated and some networks of robotic telescopes are active or planned as shown by the lists we draw up. Such equipment could be used for the training of students and for science in the Universities of Developing Countries and of New Astronomical Countries, by sending them observational data via Internet or thro

Deepak Jain, N. Panchapakesan, S. Mahajan, V. B. Bhatia

Explaining the formation and evolution of galaxies is one of the most challenging problems in observational cosmology. Many observations suggest that galaxies we see today could have evolved from the merging of smaller subsystems. Evolution of galaxies tells us how the mass or number density of the lens varies with cosmic time. Merging between the galaxies a

Noam Soker, Amos Harpaz

We analyze the angular momentum evolution from the red giant branch (RGB) to the horizontal branch (HB) and along the HB. Using rotation velocities for stars in the globular cluster M13, we find that the required angular momentum for the fast rotators is up to 1-3 orders of magnitude (depending on some assumptions) larger than that of the sun. Planets of mas

Carlos Allende Prieto, David L. Lambert

The Hipparcos mission has made it possible to constrain the positions of nearby field stars in the colour-magnitude diagram with very high accuracy. These positions can be compared with the predictions of stellar evolutionary calculations to provide information on the basic parameters of the stars: masses, radii, effective temperatures, ages, and chemical co

Stuart Bowyer, Thomas Berghoefer, Eric Korpela

We report new EUV data on the cluster of galaxies Abell 1795. These data were taken well away from a detector defect which could have compromised earlier results on this cluster. Our new observations confirm the validity of the original data set. However, we find our results are strongly influenced by the variation of the telescope sensitivity over the field

Brad K. Gibson

A summary of recent Large Magellanic Cloud distance determinations mu(LMC) is presented, with an eye towards pinpointing the source(s) of the resulting large discrepancies encountered between some of the techniques. Thirty-eight recent (1998-1999) measurements of mu(LMC) are highlighted, the extrema for which (18.07 versus 18.74) are inconsistent with one an

U. Geppert, D. Page, M. Colpi, T. Zannias

Soft Gamma-ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs) are interpreted as young highly magnetized neutron stars (NSs). Their X-ray luminosity in quiescence, exceeding 10^{35} erg s^{-1} cannot be explained as due to cooling of a highly magnetized NS, but requires as an extra heat source the decay of its magnetic field (MF). We study numerically t

Thomas A. Moore, Ronald W. Hellings

Proposed space-based gravitational wave antennas involve satellites arrayed either in an equilateral triangle around the earth in the ecliptic plane (the ecliptic-plane option) or in an equilateral triangle orbiting the sun in such a way that the plane of the triangle is tilted at 60 degrees relative to the ecliptic (the precessing-plane option). In this pap

P. Mayr

According to a recent conjecture, the moduli space of the heterotic conformal field theory on a $G\subset$ ADE singularity of an ALE space is equivalent to the moduli space of a pure $\cx N=4$ supersymmetric three-dimensional gauge theory with gauge group G. We establish this relation using geometric engineering of heterotic strings and generalize it to theo

M. Cvetic, H. Lu, C. N. Pope

We construct the complete and explicit non-linear Kaluza-Klein Ansatz for deriving the bosonic sector of the standard N=4 SO(4) gauged four-dimensional supergravity from the reduction of D=11 supergravity on S^7. This provides a way of interpreting all bosonic solutions of the four-dimensional gauged theory as exact solutions in eleven-dimensional supergravi

D. J. Fernandez C., H. C. Rosu

Using the concept of spectral engineering we explore the possibilities of building potentials with prescribed spectra offered by a modified intertwining technique involving operators which are the product of a standard first-order intertwiner and a unitary scaling. In the same context we study the iterations of such transformations finding that the scaling i

S. N. Artemenko, S. V. Zaitsev-Zotov, V. E. Minakova, P. Monceau

We derive the convective terms in the damping which determine the structure of the moving charge-density wave (CDW), and study the effect of a current flowing transverse to conducting chains on the CDW dynamics along the chains. In contrast to a recent prediction we find that the effect is orders of magnitude smaller, and that contributions from transverse c

C. Pastorino, Z. Gamba

S8 is the most stable compound of elemental sulfur in solid and liquid phases, at ambient pressure and below 400K. Three crystalline phases of S8 have been clearly identified in this range of thermodynamic parameters, although no calculation of its phase diagram has been performed yet. alpha- and gamma-S8 are orientationally ordered crystals while beta-S8 is

Alessio Filippetti, Nicola A. Hill

We present results of local spin density approximation pseudopotential calculations for the ferroelectromagnet, yttrium manganite (YMnO3). The origin of the differences between ferroelectric and non-ferroelectric perovskite manganites is determined by comparing the calculated properties of yttrium manganite in its ferroelectric hexagonal and non-ferroelectri

Zhe Xu, Carsten Greiner

Applying a microscopically motivated semi-classical Langevin description of the linear sigma model we investigate for various different scenarios the stochastic evolution of a disoriented chiral condensate (DCC) in a rapidly expanding system. Some particular emphasize is put on the numerical realisation of colored noise in order to treat the underlying dissi

M. N. Achasov, V. M. Aulchenko, K. I. Beloborodov, A. V. Berdyugin

The processes $e^+e^-\toμ^+μ^-$ and $e^+e^-\toπ^+π^-$ have been studied with SND detector at VEPP-2M $e^+e^-$ collider in the vicinity of $ϕ(1020)$ resonance. The branching ratios $B(ϕ\toμ^+μ^-)=(3.30\pm 0.45\pm 0.32)\times 10^{-4}$ and $B(ϕ\toπ^+π^-)=(0.71\pm 0.11\pm 0.09)\times 10^{-4}$ were obtained.

Brandon Carter, Anne-Christine Davis

We investigate the cosmological consequences of particle physics theories that admit stable loops of current-carrying string - vortons. In particular, we consider chiral theories where a single fermion zero mode is excited in the string core, such as those arising in supersymmetric theories with a D-term. The resulting vortons formed in such theories are exp

M. Guttormsen, M. Hjorth-Jensen, E. Melby, J. Rekstad

The density of accessible levels at low spin in the (3-He,alpha gamma) reaction has been extracted for the 161,162-Dy and 171,172-Yb nuclei. The energy shift between the level densities of the even-odd and even-even isotopes is measured as a function of excitation energy. The results are compared with predictions from various semi-empirical models. The energ

Stuart Samuel

The standard model of particle physics is analyzed for the case of a Higgs potential not favoring spontaneous electroweak symmetry breaking to gain insight into the physics of the standard model. Electroweak breaking still takes place, and quarks and leptons still acquire masses but through bosonic technicolor. This ``other'' phase of the standard mo

Thomas Vojta

Quantum phase transitions occur at zero temperature when some non-thermal control-parameter like pressure or chemical composition is changed. They are driven by quantum rather than thermal fluctuations. In this review we first give a pedagogical introduction to quantum phase transitions and quantum critical behavior emphasizing similarities with and differen

Andreas Degenhard

In this article we apply a recently invented analytical real-space renormalization group formulation which is based on numerical concepts of the density matrix renormalization group. Within a rigorous mathematical framework we construct non-perturbative renormalization group transformations for the spin-1/2 XXX Heisenberg model in the finite temperature regi

Andreas Degenhard

Based on the original idea of the density matrix renormalization group (DMRG), i.e. to include the missing boundary conditions between adjacent blocks of the blocked quantum system, we present a rigorous and nonperturbative mathematical formulation for the real-space renormalization group (RG) idea invented by L.P. Kadanoff and further developed by K.G. Wils

T. Hirayama, T. Hara

Within the context of quantum field theory in curved spacetimes, Hacyan and Sarmiento defined the vacuum stress-energy tensor with respect to the accelerated observer. They calculated it for uniform acceleration and circular motion, and derived that the rotating observer perceives a flux. Mane related the flux to synchrotron radiation. In order to investigat

The OPAL collaboration, G. Abbiendi

The measurement of small-angle Bhabha scattering is used to determine the luminosity at the OPAL interaction point for the LEP I data recorded between 1993 and 1995. The measurement is based on the OPAL Silicon-Tungsten Luminometer which is composed of two calorimeters encircling the LEP beam pipe, on opposite sides of the interaction point. The luminometer

B. Chen, H. Itoyama, T. Matsuo, K. Murakami

We study the generic $p-p^\prime$ system in the presence of constant NS 2-form $B_{ij}$ field. We derive properties concerning with the noncommutativity of D-brane worldvolume, the Green functions and the spectrum of this system. In the zero slope limit, a large number of light states appear as the lowest excitations in appropriate cases. We are able to rela

Hassan Chamati, Nicholay S. Tonchev

In this paper, we study in details the critical behavior of the ${\cal O}(n)$ quantum $ϕ^4$ model with long-range interaction decaying with the distances r by a power law as $r^{-d-σ}$ in the large n-limit. The zero-temperature critical behavior is discussed. Its alteration by the finite temperature and/or finite sizes in the space is studied. The scaling be

Hongsu Kim

Study of magnetic monopoles in the original version of Born-Infeld (BI) electrodynamics is performed. It then is realized that interesting new physics emerge and they include exotic behavior of radial electric monopole field such as its regularity as $r\to 0$ and its changing behavior with the absence or presence of the radial magnetic monopole field. This l

Boris Botvinnik

We study the question of existence of a Riemannian metric of positive scalar curvature metric on manifolds with the Sullivan-Baas singularities. The manifolds we consider are Spin and simply connected. We prove an analogue of the Gromov-Lawson Conjecture for such manifolds in the case of particular type of singularities. We give an affirmative answer when su

Kenji Sakamoto, Kiyoshi Shiraishi

Solutions for rotating boson stars in (2+1) dimensional gravity with a negative cosmological constant are obtained numerically. The mass, particle number, and radius of the (2+1) dimensional rotating boson star are shown. Consequently we find the region where the stable boson star can exist.

S. Y. Choi, Jae Sik Lee

Gluon fusion is the main production mechanism for Higgs bosons with masses up to several hundred GeV in $pp$ collisions at the CERN Large Hadron Collider. We investigate the effects of the CP-violating phases on the fusion process including both the sfermion-loop contributions and the one-loop induced CP-violating scalar-pseudoscalar mixing in the minimal su

M. Yu. Kuchiev, V. N. Ostrovsky

In the presence of an intensive laser field the radiative recombination of the continuum electron into an atomic bound state generally is accompanied by absorption or emission of several laser quanta. The spectrum of emitted photons represents an equidistant pattern with the spacing equal to the laser frequency. The distribution of intensities in this spectr

Kazuya Koyama, Kayoko Maeda, Jiro Soda

It appears difficult to construct a simple model for an open universe based on the one bubble inflationary scenario. The reason is that one needs a large mass to avoid the tunneling via the Hawking Moss solution and a small mass for successful slow-rolling. However, Rubakov and Sibiryakov suggest that the Hawking Moss solution is not a solution for the false

Rowena Ball

The classical pitchfork of singularity theory is a twice-degenerate bifurcation that typically occurs in dynamical system models exhibiting Z_2 symmetry. Non-classical pitchfork singularities also occur in many non-symmetric systems, where the total bifurcation environment is usually more complex. In this paper three-dimensional manifolds of critical points,

M. Keyl, R. F. Werner

Purification is a process in which decoherence is partially reversed by using several input systems which have been subject to the same noise. The purity of the outputs generally increases with the number of input systems, and decreases with the number of required output systems. We construct the optimal quantum operations for this task, and discuss their as

Asher Peres

When a particle decays into two fragments, the wavefunctions of the latter are spherical shells with expanding radii. In spite of this spherical symmetry, the two particles can be detected only in opposite directions.

Subhash Kak

The state function of a quantum object is undetermined with respect to its phase. This indeterminacy does not matter if it is global, but what if the components of the state have unknown relative phases? Can useful computations be performed in spite of this local indeterminacy? We consider this question in relation to the problem of the rotation of a qubit a

M. Oettel, S. Ahlig, R. Alkofer, C. Fischer

We treat baryons as bound states of scalar or axialvector diquarks and a constituent quark which interact through quark exchange. This description results as an approximation to the relativistic Faddeev equation for three quarks which yields an effective Bethe-Salpeter equation. Octet and decuplet masses and fully four-dimensional wave functions have been co

H. S. Xu, M. B. Tsang, T. X. Liu, X. D. Liu

Isotopic distributions for light particles and intermediate mass fragments have been measured for 112Sn+112Sn, 112Sn+124Sn, 124Sn+112Sn and 124Sn+124Sn collisions at E/A=50 MeV. Isotope, isotone and isobar yield ratios are utilized to obtain an estimate of the isotopic composition of the gas phase, i.e., the relative abundance of free neutrons and protons at

Omar Mustafa, Maen Odeh

The pseudoperturbative shifted-l expansion technique (PSLET) is introduced to determine nodeless states of the 2D Schrodinger equation with an arbitrary cylindrically symmetric potentials. Exact energy eigenvalues and eigenfunctions for the 2D Coulomb and harmonic oscillator potentials are reproduced. Moreover, exact energy eigenvalues, compared to those obt

Daqing Wan

In this article, we introduce a systematic new method to investigate the conjectural p-adic meromorphic continuation of Professor Bernard Dwork's unit root zeta function attached to an ordinary family of algebraic varieties defined over a finite field of characteristic p.

Ji-Ping Sha

Let xi be a smooth oriented vector bundle, with n-dimensional fibre, over a smooth manifold M. Denote by xi-hat the fibrewise one-point compactification of xi. The main purpose of this paper is to define geometrically a canonical element Upsilon(xi) in H^n(xi-hat,Q) (H^n(xi-hat,Z) tensor 1/2, to be more precise). The element Υ(ξ) is a secondary characteristi

Neil Robertson, P. D. Seymour, Robin Thomas

Given a 0-1 square matrix A, when can some of the 1's be changed to -1's in such a way that the permanent of A equals the determinant of the modified matrix? When does a real square matrix have the property that every real matrix with the same sign pattern (that is, the corresponding entries either have the same sign or are both zero) is nonsingular?

Bjorn Poonen, Michael Stoll

Let (A,λ) be a principally polarized abelian variety defined over a global field k, and let \Sha(A) be its Shafarevich-Tate group. Let \Sha(A)_\nd denote the quotient of \Sha(A) by its maximal divisible subgroup. Cassels and Tate constructed a nondegenerate pairing \Sha(A)_\nd \times \Sha(A)_\nd \rightarrow \Q/\Z. If A is an elliptic curve, then by a result

Sergei Merkulov, Lorenz Schwachhöfer

The real form Spin(6,H) in End(R^{32}) of Spin(12,C) in End(C^{32}) is absolutely irreducible and thus satisfies the algebraic identities (40) and (41). Therefore, it also occurs as an exotic holonomy and the associated supermanifold M_g admits a SUSY-invariant polynomial. This real form has been erroneously omitted in our paper. Also, the two real four-dime

Svetlana Ya. Jitomirskaya

We prove that for Diophantine \om and almost every þ, the almost Mathieu operator, (H_{ω,λ,θ}Ψ)(n)=Ψ(n+1) + Ψ(n-1) + λ\cos 2π(ωn +θ)Ψ(n), exhibits localization for λ> 2 and purely absolutely continuous spectrum for λ< 2. This completes the proof of (a correct version of) the Aubry-André conjecture.

David Ginzburg, Stephen Rallis, David Soudry

In this paper, we begin the study of poles of partial L-functions L^S(sigma tensor tau,s), where sigma tensor tau is an irreducible, automorphic, cuspidal, generic (i.e. with nontrivial Whittaker coefficient) representation of G_A x GL_m(A). G is a split classical group and A is the adele ring of a number field F. We also consider tilde{Sp}_{2n}(A) x GL_m(A)

Alex Furman

Consider a countable group Gamma acting ergodically by measure preserving transformations on a probability space (X,mu), and let R_Gamma be the corresponding orbit equivalence relation on X. The following rigidity phenomenon is shown: there exist group actions such that the equivalence relation R_Gamma on X determines the group Gamma and the action (X,mu,Gam

Alex Furman

In this paper the notion of Measure Equivalence (ME) of countable groups is studied. ME was introduced by Gromov as a measure-theoretic analog of quasi-isometries. All lattices in the same locally compact group are Measure Equivalent; this is one of the motivations for this notion. The main result of this paper is ME rigidity of higher rank lattices: any cou

Vidmantas Bentkus, Friedrich Götze

For d-dimensional irrational ellipsoids E with d >= 9 we show that the number of lattice points in rE is approximated by the volume of rE, as r tends to infinity, up to an error of order o(r^{d-2}). The estimate refines an earlier authors&#39; bound of order O(r^{d-2}) which holds for arbitrary ellipsoids, and is optimal for rational ellipsoids. As an applic

Michael B. Dillencourt, David Eppstein, Daniel S. Hirschberg

We define the geometric thickness of a graph to be the smallest number of layers such that we can draw the graph in the plane with straight-line edges and assign each edge to a layer so that no two edges on the same layer cross. The geometric thickness lies between two previously studied quantities, the (graph-theoretical) thickness and the book thickness. W

Andrey Feuerverger, Greg Martin

Rubinstein and Sarnak investigated systems of inequalities of the form pi(x;q,a_1) > ... > pi(x;q,a_r), where pi(x;q,a) denotes the number of primes up to x that are congruent to a mod q. They showed, under standard hypotheses on the zeros of Dirichlet L-functions mod q, that the set of positive real numbers x for which these inequalities hold has positive (

Adonai S. Sant&#39;Anna

We introduce the concept of indexed identity, where the usual notion of identity is a particular case. Our mathematical framework allows us a generalized method for `indexing&#39; predicates, which corresponds to `fuzzification&#39; of properties, in an intuitive sense. It can be established a relationship between this indexed mathematics and fuzzy mathemati

Stefano Montaldo, John C. Wood

We prove that harmonic morphisms preserve the Jacobi operator along harmonic maps. We apply this result to prove infinitesimal and local rigidity (in the sense of Toth) of harmonic morphisms to a sphere.

Bernhard Keller

We present a new and explicit method for lifting a tilting complex to a bimodule complex. The key ingredient of our method is the notion of a strong homotopy action in the sense of Stasheff.

Barry Simon

We present a new approach (distinct from Gel&#39;fand-Levitan) to the theorem of Borg-Marchenko that the m-function (equivalently, spectral measure) for a finite interval or half-line Schrödinger operator determines the potential. Our approach is an analog of the continued fraction approach for the moment problem. We prove there is a representation for the m

Bernhard Keller

We prove that the cyclic homology of a scheme with an ample line bundle coincides with the cyclic homology of its category of algebraic vector bundles. As a byproduct of the proof, we obtain a new construction of the Chern character of a perfect complex on a ringed space.

I. Ya. Aref&#39;eva

Black hole production in the collision of ultra-relativistic particles in the brane-world approach is considered. In particular, stability of the brane under collision with ultra-relativistic particles is discussed. As a toy model we consider the 3 dimensional version of the Randall and Sundrum solution and show that stability of the brane depends on a choic

C. Imbimbo, A. Schwimmer, S. Theisen, S. Yankielowicz

Using the relation between diffeomorphisms in the bulk and Weyl transformations on the boundary we study the Weyl transformation properties of the bulk metric on shell and of the boundary action. We obtain a universal formula for one of the classes of trace anomalies in any even dimension in terms of the parameters of the gravity action.

Laurent Houart, Yolanda Lozano

We discuss in a systematic way all the possible realisations of branes of M and type II theories as topological solitons of a brane-antibrane system. The classification of all the possibilities, consistent with the structure of the theory, is achieved by studying the Wess-Zumino terms in the worldvolume effective actions of the branes of M-theory and their r

Andrey Dubin

We introduce the basics of the nonabelian duality transformation of SU(N) or U(N) vector-field models defined on a lattice. The dual degrees of freedom are certain species of the integer-valued fields complemented by the symmetric groups&#39; \otimes_{n} S(n) variables. While the former parametrize relevant irreducible representations, the latter play the ro

Hajime Aoki, Satoshi Iso, Hikaru Kawai, Yoshihisa Kitazawa

We study the thermodynamic behavior of branched polymers. We first study random walks in order to clarify the thermodynamic relation between the canonical ensemble and the grand canonical ensemble. We then show that correlation functions for branched polymers are given by those for $ϕ^3$ theory with a single mass insertion, not those for the $ϕ^3$ theory the

Yosuke Imamura

Via T-duality, a stack of unwrapped type 0 NS5-branes is transformed into a Kaluza-Klein monopole with A_n type singularity at its center. The spectrum of twisted modes at the singularity contains tachyonic modes. We show that, in certain parameter region, this tachyonic spectrum is completely reproduced as modes of the bulk tachyon field localized on a clas

Petr Jizba

We concern with various aspects of equilibrium and non-equilibrium quantum field theory.

D. Anselmi

I review recent results on conformal field theories in four dimensions and quantum field theories interpolating between conformal fixed points, supersymmetric and non-supersymmetric. The talk is structured in three parts: i) central charges, ii) anomalous dimensions and iii) quantum irreversibility.

M. Niedermaier

Suppose a regularised functional integral depends holomorphically on a parameter that receives only a finite renormalization. Can one expect the correlation functions to retain the analyticity in the parameter after removal of the cutoff(s)? We examine the issue in the Sinh-Gordon theory by computing the intrinsic 4-point coupling as a function of the Lagran

Abilio De Freitas, Sebastian Salamo

From the algebraic treatment of the quasi-solvable systems, and a q-deformation of the associated $su(2)$ algebra, we obtain exact solutions for the q-deformed Schrodinger equation with a 3-dimensional q-deformed harmonic oscillator potential.

Anatolij I. Bugrij, Vitalij N. Shadura

In two-dimensional lattice fermion model a determinant representation for the two-point correlation function of the twist field in the disorder phase is obtained. This field is defined by twisted boundary conditions for lattice fermion field. The large distance asymptotics of the correlation function is calculated at the critical point and in the scaling reg

Andrei V. Afanasev

I use the formalism of skewed parton distributions (SPD) to describe elastic form factors of the nucleon. The results are consistent with approximate dipole behavior of $G_{Mp}(Q^2)$ and recent JLab data for the ratio of the proton form factors $G_{Ep}/G_{Mp}$ at $Q^2\leq 3.5$ GeV$^2$. Using the Angular Momentum Sum Rule, I obtain a numerical estimate for th

Alan. R. White

The U(1) triangle anomaly is present, as an infra-red divergence, in the six-reggeon triple-regge interaction vertex obtained from a maximally non-planar Feynman diagram in the full triple-regge limit of three-to-three quark scattering.

Vittorio Del Duca, Lance Dixon, Fabio Maltoni

Recently, a color decomposition using structure constants was introduced for purely gluonic tree amplitudes, in a compact form involving only the linearly independent subamplitudes. We give two proofs that this decomposition holds for an arbitrary number of gluons. We also present and prove similar decompositions at one loop, both for pure gluon amplitudes a

Paul Singer

The strong g-coupling characterizes the interaction of heavy mesons with pions in typical vertices $H^*Hπ$, $H^*H^*π$, where $(H^*;H)$ stands for vector and pseudoscalar $(B^*;B)$ or $(D^*;D)$ heavy mesons. Its estimation by different theoretical methods has led to a wide range of possible values. We describe a new approach to the determination of g, which e

P. Bialas, L. Bogacz, Z. Burda, D. Johnston

We discuss the finite size behaviour in the canonical ensemble of the balls in boxes model. We compare theoretical predictions and numerical results for the finite size scaling of cumulants of the energy distribution in the canonical ensemble and perform a detailed analysis of the first and third order phase transitions which appear for different parameter v

K. Ackerstaff

Cross section ratios for deep-inelastic scattering from 14N and 3He with respect to 2H have been measured by the HERMES experiment at DESY using a 27.5 GeV positron beam. The data cover a range in the Bjorken scaling variable x between 0.013 and 0.65, while the negative squared four-momentum transfer Q^2 varies from 0.5 to 15 GeV^2. The data are compared to

The OPAL collaboration, G. Abbiendi

A study of W+W- events accompanied by hard photon radiation produced in e+e- collisions at LEP is presented. Events consistent with two on-shell W-bosons and an isolated photon are selected from 183pb^-1 of data recorded at root{s}=189GeV. From these data, 17 W+W-gamma candidates are selected with photon energy greater than 10GeV, consistent with the Standar

J. A. Crittenden

The HERA collider experiments H1 and ZEUS have established extensive measurement programs for diffractive vector-meson production processes during the first six years of their operation. The results provide stringent phenomenological tests of quantum chromodynamical descriptions of hard diffraction. We discuss recent topical results on Upsilon photoproductio

P. Eerola

Investigations of B hadrons are expected to break new ground in measuring CP-violation effects. This series of BEAUTY conferences, originating from the 1993 conference in Liblice, has contributed significantly in developing ideas of CP-violation measurements using B hadrons and formulating and comparing critically the B-physics experiments. In the &#39;99 co

H. Casini, R. Montemayor

In this paper we develop a formalism to describe a superfluid in a gravitational background. This formalism is based on a covariant generalization of the field description for a superconductor in terms of a U(1) spontaneous symmetry breaking. We study the stability of the solutions for a vortexless fluid and the force acting on vortices in the fluid, which i

Ulrich H. Gerlach

The four Rindler quadrants of a pair of oppositely accelerated frames are identified as a (Lorentzian) Mach-Zehnder interferometer. The Rindler frequency dependence of the interference process is expressed by means of a (Lorentzian) differential cross section. The Rindler frequencies of the waves in the two acccelerated frames can be measured directly by mea

A. Ossipov, Tsampikos Kottos, T. Geisel

We study the distribution of phases and of Wigner delay times for a one-dimensional Anderson model with one open channel. Our approach, based on classical Hamiltonian maps, allows us an analytical treatment. We find that the distribution of phases depends drastically on the parameter $σ_A = σ/sin k$ where $σ^2$ is the variance of the disorder distribution an

V. M. Apel, M. J. Sánchez, G. Chiappe

We consider a bidimensional discrete annular cavity with surface roughness (SR) threaded by a magnetic flux. In the ballistic regime and at half filling, localized border-states show up. These border states contribute coherentely to the persistent current and the magnitude of the typical current $I_{typ}$ is enhaced with respect to their value in the absence

Manfred Sigrist, Daniel F. Agterberg

We investigate the influence of domain walls on the vortex dynamics in superconductors with multi-component order parameters. We show that, due to their complex structure domain walls can carry vortices with fractional flux quanta. The decay of conventional vortices into fractional ones on domain walls is examined. This decay presents an extraordinarily stro

F. F. Ferreira, J. F. Fontanari

Within the replica framework we study analytically the instance space of the number partitioning problem. This classic integer programming problem consists of partitioning a sequence of N positive real numbers $\{a_1, a_2,..., a_N}$ (the instance) into two sets such that the absolute value of the difference of the sums of $a_j$ over the two sets is minimized

Jing Shi, X. S. Ling, Ruixing Liang, D. A. Bonn

A giant peak in the temperature dependence of the screening current is observed in the ac magnetic response of an ultra-pure YBa$_2$Cu$_3$O$_{6.993}$ crystal in a magnetic field. At H = 2.0 T ({\bf $H$}$||${\bf c}), the screening current density $J_c(T)$ exhibits a 35-fold rise with 0.5 K increase in temperature, indicating an abrupt $10^3$-fold collapse in

Wonkee Kim, Jian-Xin Zhu, C. S. Ting

Based on the linearized Eilenberger equations, the upper critical field $(H_{c2})$ of mixed d- and s-wave superconductors has been microscopically studied with an emphasis on the competing effects of mass anisotropy and spin Zeeman coupling. We find the mass anisotropy always enhance $H_{c2}$ while the Zeeman interaction suppresses $H_{c2}$. As required by t

S. V. Demishev, A. A. Pronin, N. E. Sluchanko, A. N. Vasil&#39;ev

Temperature dependence in the interval 4.2-300 K and the critical behavior of the dielectric function along c-axis in NaV2O5 have been studied in the frequency range 1 MHz-1 GHz. These data were analyzed together with literature data concerning specific heat, magnetic losses and ultrasonic velocity. We found that all results support the idea about universali

P. R. A. Campos, M. T. Sonoda, J. F. Fontanari

We investigate through numerical simulations the effect of selection on two summary statistics for nucleotide variation in a sample of two genes from a population of N asexually reproducing haploid individuals. One is the mean time since two individuals had their most recent common ancestor ($\bar{T_s}$), and the other is the mean number of nucleotide differ

Orjan Festin, Peter Svedlindh, Beom Jun Kim, Petter Minnhagen

The flux noise spectrum and complex impedance for a 500 Å thick YBCO film are measured and compared with predictions for two dimensional vortex fluctuations. It is verified that the complex impedance and the flux noise spectra are proportional to each other, that the logarithm of the flux noise spectra for different temperatures has a common tangent with slo

Ricardo Perez, Augusto Gonzalez

Confined excitonic complexes in two dimensions, consisting of N_e electrons and N_h holes, are studied by means of Bethe-Goldstone equations. Systems with up to twelve pairs, and asymmetric configurations with N_e \ne N_h are considered. The weak confinement regime gives indication of weak binding or even unbinding in the triexciton and the four-exciton syst

H. Schomerus, C. W. J. Beenakker

The supersymmetry technique [A. V. Kolesnikov and K. B. Efetov, Phys. Rev. Lett. 83, 3689 (1999)] predicts a two-scale behavior of wavefunction decay in disordered wires in the crossover regime from preserved to broken time-reversal symmetry. We have tested this prediction by a transmission approach, relying on the Borland conjecture that relates the decay l

Hiroshi Kuratsuji, Shouhei Kakigi, Hiroyuki Yabu

A theoretical study is given of a new type of optical vortex in nonlinear anisotropic media. This is realized as a special solution of the two-component non-linear Schroedinger equation. The vortex is inherent in the spin texture that is caused by an anisotropy of dielectric tensor, for which a role of spin is played by the Stokes vector (or pseudo-spin). By

Choon-Peng Chng, Jian-Sheng Wang

The system under study is a twin-layered square lattice gas at half-filling, being driven to non-equilibrium steady states by a large, finite `electric&#39; field. By making intra-layer couplings unequal we were able to extend the phase diagram obtained by Hill, Zia and Schmittmann (1996) and found that the tri-critical point, which separates the phase regio

H. Amitsuka, M. Sato, N. Metoki, M. Yokoyama

We have performed elastic neutron-scattering experiments on the heavy-electron compound URu_2Si_2 for pressure P up to 2.8 GPa. We have found that the antiferrmagnetic (100) Bragg reflection below T_m ~ 17.5 K is strongly enhanced by applying pressure. For P < 1.1 GPa, the staggered moment mu_o at 1.4 K increases linearly from ~ 0.017(3) mu_B to ~ 0.25(2) mu

Jurgen Horbach, Walter Kob, Kurt Binder

We present the results of large scale computer simulations in which we investigate the static and dynamic properties of sodium disilicate and sodium trisilicate melts. We study in detail the static properties of these systems, namely the coordination numbers, the temperature dependence of the Q^(n) species and the static structure factor, and compare them wi

H. Schomerus, K. M. Frahm, M. Patra, C. W. J. Beenakker

The quantum-limited linewidth of a laser cavity is enhanced above the Schawlow-Townes value by the Petermann factor K, due to the non-orthogonality of the cavity modes. We derive the relation between the Petermann factor and the residues of poles of the scattering matrix and investigate the statistical properties of the Petermann factor for cavities in which

Matthias Steinmetz, Julio F. Navarro

We discuss possible origins of scaling laws relating structural properties of disk galaxies within the context of hierarchically clustering theories of galaxy formation. Using gasdynamical simulations that incorporate the effects of star formation we illustrate these global trends and highlight the difficulties faced by models that envision disk galaxies as