August 1997 arXiv papers — page 11

Ch. Schaab, B. Hermann, F. Weber, M. K. Weigel

The general statement that strange stars cool more rapidly than neutron stars is investigated in greater detail. It is found that the direct Urca process could be forbidden not only in neutron stars but also in strange stars. If so, strange stars would be slowly cooling and their surface temperatures would be more or less indistinguishable from those of slow

G. D. Lythe

Analysis is presented of a system whose dynamics are dramatically simplified by tiny amounts of additive noise. The dynamics divide naturally into two phases. In the slower phase, trajectories are close to an invariant manifold; this allows small random disturbances to exert a controlling influence. A map is derived which provides an accurate description of

David R. Nelson, Nadav M. Shnerb

The time evolution of spatial fluctuations in inhomogeneous d-dimensional biological systems is analyzed. A single species continuous growth model, in which the population disperses via diffusion and convection is considered. Time-independent environmental heterogeneities, such as a random distribution of nutrients or sunlight are modeled by quenched disorde

Weimin Chen

We established existence of periodic Reeb orbits for a large class of tight contact structures on closed 3-manifolds, notably the Stein fillable structures, based on a fundamental theorem of Cliff Taubes on symplectic 4-manifolds.

E. L. Gubankova, F. Wegner

Modified similarity renormalization (MSR) of Hamiltonians is proposed, that performes by means of flow equations the similarity transformation of Hamiltonian in the particle number space. This enables to renormalize in the energy space the field theoretical Hamiltonian and makes possible to work in a severe trancated Fock space for the renormalized Hamiltoni

Yuval Ne'eman

A superconnection is a supermatrix whose even part contains the gauge-potential one-forms of a local gauge group, while the odd parts contain the (0-form) Higgs fields; the combined grading is thus odd everywhere. We demonstrate that the simple supergroup ${\bar P}(4,R)$ (rank=3) in Kac' classification (even subgroup $\bar {SL}(4,R)$) prverline {SL}(4,R)

J. Segura

We discuss how the measurement of the $\barν_{e}-e^{-}$ elastic cross section at reactor energies can be used to extract new information on the neutrino oscillation parameters. We also consider the magnetic moment contribution and show how both effects tend to cancel each other when the total cross section is measured; to achieve the separation of each of th

Sanjay Jain

In a universe whose elementary constituents are point particles there does not seem to be any obvious mechanism for avoiding the initial singularities in physical quantities in the standard model of cosmology. In contrast in string theory these singularities can be absent even at the level where spacetime is treated classically. This is a consequence of the

K. C. Chase, A. Z. Mekjian, L. Zamick

The thermodynamic properties of bosons moving in a harmonic trap in an arbitrary number of dimensions are investigated in the grand canonical, canonical and microcanonical ensembles by applying combinatorial techniques developed earlier in statistical nuclear fragmentation models. Thermodynamic functions such as the energy and specific heat are computed exac

A. Levinson

The theory of gamma-ray emission from e$^{\pm}$ jets and the implications for jet formation, dynamics and structure are reviewed. In particular, possible carriers of the jet's thrust on small scales, the transition from electromagnetic to particle dominance in Poynting flux jets, formation of pair cascades, synchrotron emission by cascading pairs, and fo

Robert F. Coker, F. Melia

Spectral and kinematic studies suggest that the nonthermal radio source Sgr A*, located at the center of the Milky Way, is a supermassive compact object with a mass 2-3 million solar masses. Winds from nearby stars, located approximately 0.06 pc to the east of Sgr A*, should, in the absence of any outflow from the putative black hole itself, be accreting ont

Remo Garattini

We consider a homogeneous space X=(X,d,m) of dimension $ν\geq 1$ and a local regular Dirichlet form in L^{2}(X,m). We prove that if a Poincaré inequality holds on every pseudo-ball B(x,R) of X, with local characteristic constant c_{0}(x) and c_{1}(r), then a Green's function estimate from above and below is obtained. A Saint-Venant-like principle is reco

Tomasz Brzezinski, Piotr M. Hajac

The notion of a coalgebra-Galois extension is defined as a natural generalisation of a Hopf-Galois extension. It is shown that any coalgebra-Galois extension induces a unique entwining map $ψ$ compatible with the right coaction. For the dual notion of an algebra-Galois coextension it is also proven that there always exists a unique entwining structure compat

Tetsu Kitayama, Shin Sasaki, Yasushi Suto

We compute the number counts of clusters of galaxies, the logN-logS relation, in several X-ray and submm bands on the basis of the Press-Schechter theory. We pay particular attention to a set of theoretical models which well reproduce the ROSAT 0.5-2 keV band logN-logS, and explore possibilities to further constrain the models from future observations with A

D. -G. Welsch, M. Dakna, L. Knoll, T. Opatrny

The problem of photon adding and subtracting is studied, using conditional output measurement on a beam splitter. It is shown that for various classes of states the corresponding photon-added and -subtracted states can be prepared. Analytical results are presented, with special emphasis on photon-added and -subtracted squeezed vacuum states, which are found

T. Opatrny, M. Dakna, D. -G. Welsch

A method for direct sampling of the exponential moments of canonical phase from the data recorded in balanced homodyne detection is presented. Analytical expressions for the sampling functions are shown which are valid for arbitrary states. A numerical simulation illustrates the applicability of the method and compares it with the direct measurement of phase

R. J. Furnstahl, James C. Hackworth

Recent studies show that successful relativistic mean-field models of nuclei are consistent with naive dimensional analysis and naturalness, as expected in low-energy effective field theories of quantum chromodynamics. The nonrelativistic Skyrme energy functional is found to have similar characteristics.

Ch. Elster, J. H. Thomas, W. Gloeckle

The two-body t-matrix is calculated directly as function of two vector momenta for different Malfliet-Tjon type potentials. At a few hundred MeV projectile energy the total amplitude is quite a smooth function showing only a strong peak in forward direction. In contrast the corresponding partial wave contributions, whose number increases with increasing ener

M. Reuter, C. Wetterich

We employ nonperturbative flow equations for an investigation of the effective action in Yang-Mills theories. We compute the effective action $Γ[B]$ for constant color magnetic fields $B$ and examine Savvidy's conjecture of an unstable perturbative vacuum. Our results indicate that the absolute minimum of $Γ[B]$ occurs for B=0. Gluon condensation is desc

S. M. H. Wong

The uncertainty in the equilibration in heavy ion collisions due to the choice of the value of the coupling is examined. The results of the equilibration are indeed affected by this choice. In particular, a variation of $\a_s$ from 0.3 to 0.5 reduces the parton phase of the plasma by as much as 4.0 fm/c and increasing coupling causes a reduction in the gener

N. Armesto, M. A. Braun

The odderon singularity is studied in perturbative QCD in the framework of the Bartels-Kwieciński-Praszalowicz (BKP) equation. Arguments for the odderon intercept being exactly equal to unity are given. Besides, a variational method based on a complete system of one-gluon functions is presented. For the odderon, the highest intercept calculated by this metho

K. Yaman, C. Jeppesen, C. M. Marques

We study the depletion interaction between spherical particles of radius R immersed in a dilute solution of rigid rods of length L. The computed interaction potential is, within numerical accuracy, exact for any value of L/R. In particular we find that for L of order R, the depth of the depletion well is smaller than the prediction of the Derjaguin approxima

L. A. Anchordoqui, M. T. Dova, L. N. Epele, J. D. Swain

We re-examine the interaction of ultra high energy nuclei with the microwave background radiation. We find that the giant dipole resonance leaves a new signature in the differential energy spectrum of iron sources located around 3 Mpc: A depression before the bump which is followed by the expected cutoff.

Z. Bagoly, A. Meszaros, I. Horvath, L. G. Balazs

We have carried out a principal component analysis for 625 gamma-ray bursts in the BATSE 3B catalog for which non-zero values exist for the nine measured variables. This shows that only two out of the three basic quantities of duration, peak flux and fluence are independent, even if this relation is strongly affected by instrumental effects, and these two ac

R. Vogt

A reexamination of hadronic comover scattering indicates that this mechanism cannot explain the observed $ψ$ suppression in Pb+Pb interactions. The possibility of quark-gluon plasma formation is therefore considered.

Gilberto Colangelo, Elisabetta Pallante

We calculate the divergences of the generating functional of quenched Chiral Perturbation Theory at one loop, and renormalize the theory by an appropriate definition of the counterterms. We show that the quenched chiral logarithms can be reabsorbed in the renormalization of the B_0 parameter which, at lowest order, is proportional to the vacuum expectation v

C. M. Hull

A non-abelian generalisation of a theory of gravity coupled to a 2-form gauge field and a dilaton is found, in which the metric and 3-form field strength are Lie algebra-valued. In the abelian limit, the curvature with torsion is self-dual in four dimensions, or has SU(n) holonomy in $2n$ dimensions. The coupling to self-dual Yang-Mills fields in 4 dimension

Bohdan Paczynski, K. Z. Stanek

We compare red clump stars with parallaxes known to better than 10% in the Hipparcos catalog and corrected for the interstellar extinction, with the OGLE red clump stars in Baade's Window also corrected for the interstellar extinction. There are $\sim 600$ and $\sim 10,000$ such stars in the two data sets, respectively. We find empirically that the avera

M. Abou Zeid, C. M. Hull

The geometry of (2,1) supersymmetric sigma-models with isometry symmetries is discussed. The gauging of such symmetries in superspace is then studied. We find that the coupling to the (2,1) Yang-Mills supermultiplet can be achieved provided certain geometric conditions are satisfied. We construct the general gauged action, using an auxiliary vector to genera

Denis V. Juriev

The paper is devoted to a description of quantum group structures in the geometric quantization of a self-interacting string field, which appear under a transition from a tree-level of the theory to the account of loop effects in nonperturbative quantum field theory of strings.

E787 Collaboration, P. Kitching, T. Nakano, M. Rozon

The first observation of the decay K^+ --> pi^+ gamma gamma is reported. A total of 31 events was observed with an estimated background of 5.1 +- 3.3 events in the pi+ momentum range from 100 MeV/c to 180 MeV/c. The corresponding partial branching ratio, B(K+ -> pi+ gamma gamma, 100 MeV/c < P_pi^+ < 180 MeV/c), is (6.0 +- 1.5 (stat) +- 0.7 (sys)) x 10^{-7}.

Richard Cleve, Artur Ekert, Chiara Macchiavello, Michele Mosca

Quantum computers use the quantum interference of different computational paths to enhance correct outcomes and suppress erroneous outcomes of computations. A common pattern underpinning quantum algorithms can be identified when quantum computation is viewed as multi-particle interference. We use this approach to review (and improve) some of the existing qua

Stefan Leupold, Wolfram Peters, Ulrich Mosel

Using a simple parametrization of Breit-Wigner type for the hadronic side of the QCD sum rule for $ρ$ mesons in vacuum as well as in a nuclear medium we explore the range of values for the mass and the width of the $ρ$ meson which are compatible with the operator product expansion.

R. A. Arndt, C. H. Oh, I. I. Strakovsky, R. L. Workman

A partial-wave analysis of NN elastic scattering data has been completed. This analysis covers an expanded energy range, from threshold to a laboratory kinetic energy of 2.5 GeV, in order to include recent elastic pp scattering data produced by the EDDA collaboration at COSY. The results of both single-energy and energy-dependent analyses are described.

Richard Arndt, Chang-Heon Oh, Igor Strakovsky, Ron Workman

A combined analysis of the main reactions of the two-baryon system (pp-->pp, pid-->pid, and pid-->pp) over the sqrt{s} interval from pion threshold to 2.4 GeV has been completed. The overall phase in pid-->pp has now been determined. The combined analysis has resulted in an improved fit to the pid elastic and pid-->pp databases.

S. G. Cooper

To understand recently established empirical p + alpha potentials, RGM calculations followed by inversion are made to study contributions of the d + 3He reaction channels and deuteron distortion effects to the p + alpha potential. An equivalent study of the d + 3He potential is also presented. The contributions of exchange non-locality to the absorption are

T. Mart, D. Kusno, C. Bennhold, L. Tiator

In the framework of the impulse approximation we study the photoproduction of the hypertriton $^3_Λ$H by using realistic $^3$He wave functions obtained as solutions of Faddeev equations with the Reid soft-core potential for different $^3_Λ$H wave functions. We obtain relatively small cross sections of the order of 1 nb. We also find that the influence of Fer

Sanjay K. Ghosh, S. C. Phatak

The mass of dihyperon with spin, parity $J^π=0^{+}$ and isospin $I = 0$ is calculated in the framework of Chiral colour dielectric model. The wave function of the dihyperon is expressed as a product of two colour-singlet baryon clusters. Thus the quark wave functions within the cluster are antisymmetric. Appropriate operators are then used to antisymmetrize

C. Beck, R. Nouicer, ; S. J. Sanders, ; A. Szanto de Toledo

A high-resolution study of fragment-fragment-$γ$ triple coincident measurements of the symmetric-mass fission exit-channel from the ^{28}Si+^{28}Si reaction has been performed at the VIVITRON Tandem facility by using the EUROGAM Phase II $γ$-ray spectrometer. The bombarding energy E_{lab}(^{28}Si) = 111.6 MeV has been chosen to populate a well known quasi-mo

J. de Boer, M. B. Halpern

The Virasoro master equation describes a large set of conformal field theories known as the affine-Virasoro constructions, in the operator algebra (affine Lie algebra) of the WZW model, while the Einstein equations of the general non-linear sigma model describe another large set of conformal field theories. This talk summarizes recent work which unifies thes

Vadim S. Kaplunovsky, Jan Louis

Stabilizing a heterotic string vacuum with a large expectation value of the dilaton and simultaneously breaking low-energy supersymmetry is a long-standing problem of string phenomenology. We reconsider these issues in light of the recent developments in F-theory.

Ram Brustein, Richard Madden

We construct, for the first time, a model of graceful exit transition from a dilaton-driven inflationary phase to a decelerated Friedman-Robertson-Walker era. Exploiting a demonstration that classical corrections can stabilize a high curvature string phase while the evolution is still in the weakly coupled regime, we show that if additional terms of the type

Subir Ghosh

The classical and quantum aspects of planar Coulomb interactions have been studied in detail. In the classical scenario, Action Angle Variables are introduced to handle relativistic corrections, in the scheme of time-independent perturbation theory. Complications arising due to the logarithmic nature of the potential are pointed out. In the quantum case, har

Zhang Yang

It is pointed out that "the colorless objects" in diffractive lepton-nucleon scattering in the small-$x_B$ region can be probed by measuring the scaled factorial moments of final-state-hadrons and the dependence of their scaling behavior upon the diffractive kinematic variables. The Monte Carlo implementation of RAPGAP and JETSET are discussed as illustrativ

N. V. Mikheev, L. A. Vassilevskaya

Some results of an external electromagnetic field influence on axion decays are presented. It is shown that the field catalyzes substantially these processes. The result describing the axion decay $a \to f \tilde f$ we have obtained can be of use to re-examine the lower limit on the axion mass in case of possible existence of strong magnetic fields at the ea

A. L. Kataev

We present the analytical expressions for the contributions of the order $O(\barα~\barα_s)$ and $O(\barα^2)$ corrections to the decay width of the Standard Model Higgs boson into the $\bar{b}b$-pair. The numerical value of the mixed QED and QCD correction of order $O(\barα~\barα_s)$ is comparable with the previously calculated terms in the perturbative serie

W. Roberts

We discuss the application of the tensor formalism of HQET to the strong decays of heavy hadrons. We treat both meson and baryon decays, and note that all of our results are in agreement with the `spin-counting&#39; arguments of Isgur and Wise. We briefly discuss the possible extension of the formalism to include $1/m$ corrections.

N. N. Nikolaev, J. Speth, B. G. Zakharov, .

We compaWe compare the absorptive corrections to the one pion exchange in $pp\to Xn$ and $ep\to e&#39;Xn$ reactions. It is shown that the absorption is stronger in the case of $pp$ collision. The difference in strength of the absorption for the $pp\to Xn$ and $ep\to e&#39;Xn$ reactions breaks the factorization peculiar to the pure one pion exchange. We evalu

L. Accardi, I. Ya. Aref&#39;eva, I. V. Volovich

Photon splitting cascades in a magnetic field are considered. It is shown, in the stochastic limit approximation, that photons in cascades might form entangled states (``triphons&#39;&#39;) and that they obey not Bose but a new type of statistics, the so called infinite or quantum Boltzmann statistics. These states belong to an interacting Fock space which i

Marco Aurelio Diaz

We review the extraction of fundamental supersymmetric parameters from experimental observables related to the detection of charginos and selectrons at $e^+e^-$ colliders. We consider supergravity models with universal scalar and gaugino masses and radiatively broken electroweak symmetry. Two scenarios are considered: (a) The lightest chargino is light enoug

R. Casalbuoni, A. Deandrea, S. De Curtis, D. Dominici

In this work we have studied the phenomenological properties at future e+e- linear colliders of two models of strong electroweak symmetry breaking, characterized by the presence of new spin one strong interacting resonances.

E. Keith, Ernest Ma

We consider the decay of the $Z$ boson into three pseudoscalar bosons in a general two-Higgs-doublet model. Assuming $m_A$ to be very small, and that of the two physical neutral scalar bosons $h_1$ and $h_2$, $A$ only couples to $Z$ through $h_1$, we find the $Z \to A A A$ branching fraction to be negligible for moderate values of $\tan β\equiv v_2/v_1$, if

R. Balbinot, A. Fabbri, L. Mazzacurati

In a one parameter family of dilaton gravity theories which allow the coupling of the dilaton to gravity and to a U(1) gauge field to differ, we have found the existence of everywhere regular spacetimes describing black holes hiding expanding universes inside their horizon.

J. M. Landsberg

This is an elementary introduction to exterior differential systems motivated by two examples: minimal submanifolds and the isometric embedding problem. The two main goals of the lectures are: 1. To explain how to find an appropriate geometric setting for studying a given system of pde. 2. To explain the Cartan algorithm to determine the moduli space of loca

Richard S. Palais

This paper is an expository account of the development of soliton mathematics, from its inception in famous numerical experiments of Fermi-Pasta-Ulam and Zabusky-Kruskal to the recent synthesis of Terng-Uhlenbeck (dg-ga/9707004) that explains hidden symmetries of soliton equations in terms of loop-groups acting by dressing transformations. The inverse scatte

Pinaki Majumdar, Peter Littlewood

We discuss magnetotransport in a low density electron gas coupled to spin fluctuations near and above a ferromagnetic transition. Provided the density is low enough ($n \lesssim 1/ξ^{3}(T)$, with $ξ(T)$ the ferromagnetic correlation length), spin polarons form in an intermediate temperature regime above $T_c$. Both in the spin polaron regime, and in the itin

Rashmi Ray, Joan Soto

We present a quantum field theoretical analysis of a $ν= 1$ quantum Hall system when the effective Landé $g$ factor is small. We clearly demonstrate that the ground state of the system is ferromagnetic. We note that it is the short range component of the Coulomb interaction which is instrumental in aligning the spins. We then go on to derive the effective la

Jae Woo Lee

We have studied kinetics of random sequential adsorption of mixtures on a square lattice using Monte Carlo method. Mixtures of linear short segments and long segments were deposited with the probability $p$ and $1-p$, respectively. For fixed lengths of each segment in the mixture, the jamming limits decrease when $p$ increases. The jamming limits of mixtures

Reinhold Egger, Alexander O. Gogolin

The low-energy theory for single-wall carbon nanotubes including Coulomb interactions is derived and analyzed. It describes two fermion chains without interchain hopping but coupled in a specific way by the interaction. The strong-coupling properties are studied by bosonization, and consequences for experiments on single armchair nanotubes are discussed.

Q. Daniel Wang, Eric V. Gotthelf

We report the results of ROSAT and ASCA X-ray observations of the supernova remnant N157B (or 30 Dor B, SNR 0539-69.1) in the Large Magellanic Cloud. For comparison, we also briefly describe the results on SNR 0540-69.3, the only confirmed Crab-like remnant in the Cloud. The X-ray emission from N157B can be decomposed into a bright comet-shaped feature, supe

Uffe Hellsten, D. N. C. Lin

Within collapsing protogalaxies, thermal instability leads to the formation of a population of cool fragments which are confined by the pressure of a residual hot background medium. The critical mass required for the cold clouds to become gravitationally unstable and to form stars is determined by both their internal temperature and external pressure. We per

G. Leyshon, Stephen A. Eales

We present the results of K-band imaging polarimetry of seven 3CR radio galaxies at redshifts (z) between 0.7 and 1.2. We find strong evidence for polarization in three sources: 3C 22, 3C 41 and 3C 114. Of these, 3C 41 shows strong evidence of having a quasar core whose infrared light is scattered by dust. We also find some evidence for polarization in 3C 54

Neil J. Cornish, David N. Spergel, Glenn D. Starkman

Observations of microwave background fluctuations can yield information not only about the geometry of the universe, but potentially about the topology of the universe. If the universe is negatively curved, then the characteristic scale for the topology of the universe is the curvature radius. Thus, if we are seeing the effects of the geometry of the univers

Jochen M. Braun, Dominik J. Bomans, Jean-Marie Will, Klaas S. de Boer

The youngest stellar populations of a &#39;J&#39;-shaped region (400 pc strip E-W across LH 77 and 850 pc S-N) inside the supergiant shell (SGS) LMC 4 (with a diameter of 1.4 kpc) have been analysed with CCD photometry in B,V passbands. Isochrone fitting to the colour-magnitude diagrams yields ages in the range from 9 Myr to 16 Myr without correlation with t

Christopher B. Moore, Jacqueline N. Hewitt

We report the results of monitoring the four images of the gravitational lens MG 0414+0534 at 15 GHz. In 35 VLA maps spanning 180 days, we measure root-mean-square variations in the image light curves of ~3.5% mostly due to variations in the flux density calibration. The flux ratios, which are independent of flux density calibration variations, show root-mea

V. Celebonovic, S. Samurovic, M. M. Cirkovic

The purpose of this note is to present a possible explanation of the spectral distorsions that could be observed in the CMBR spectrum.We propose that distor- sions of the order of $y \sim 10^{- 6}$ can be interpreted as a consequence of radiative decay of massive tau neutrionos.We have also obtained a constraint on the value of the decaying neutrino mass.

Coel Hellier, Koji Mukai, A. P. Beardmore

We report the first observed outburst of the magnetic cataclysmic variable XY Ari. X-ray observations show a flux increase by an order of magnitude the day after the first signs of outburst. During the 5-d duration the X-ray spin pulse is greatly enhanced and the X-ray spectrum far more absorbed. We suggest that the inner disc pushes inwards during outburst,

Coel Hellier

RXTE observed 20 eclipse egresses of the intermediate polar XY Ari in order to study the size and structure of the X-ray emitting accretion regions. The spin-phase averaged egress lasts 26 s, implying a white dwarf radius of 4.3-7.0 10^8 cm. The individual egresses occur later in orbital phase with later spin phase, as expected if the white dwarf spins in th

Richard S Ellis

Although it is just over a year since the data was made public, the HDF exposure has stimulated considerable progress towards our understanding of the faint galaxy population. I present a brief personal account of the history of faint galaxy studies culminating in the HDF, and describe what I consider to be the main highlights thus far from this remarkable i

J. P. Beaulieu, R. Buchler, M. J. Goupil, Z. Kollath

Using CCD photometry obtained by the EROS collaboration in 1991-1993, we have discovered an LMC variable star with a light curve that is oscillating with a mean period of $\sim 14$ days and an amplitude of $\sim$ 0.3 mag. The oscillations appear with irregular amplitude variations. The Fourier spectrum shows that the pulsation of this star is phase locked be

K. P. Singh, C. R. Shrader, I. M. George

We present results on the X-ray spectra of the radio-loud, high-polarization quasar, PKS 1510-089, based on new data obtained using ASCA, and from archival ROSAT data. The X-ray spectrum obtained by ASCA is unusually hard, with the photon index=1.30+-0.06, while the (non-simultaneous) ROSAT data indicate a steeper spectrum (1.9+-0.3). The X-ray flux at 1 keV

Jan de Boer, Yaron Oz

The fivebrane of M theory is used in order to study the moduli space of vacua of confining phase N=1 supersymmetric gauge theories in four dimensions. The supersymmetric vacua correspond to the condensation of massless monopoles and confinement of photons. The monopole and meson vacuum expectation values are computed using the fivebrane configuration. The co

Vincent R. Eke, Julio F. Navarro, Carlos S. Frenk

We present results of N-body/gasdynamical simulations designed to investigate the evolution of X-ray clusters in a flat, low-density, cold dark matter (CDM) cosmogony. The density profile of the dark matter component can be fitted rather accurately by the simple formula originally proposed by Navarro, Frenk & White to describe the structure of clusters in a

E787 Collaboration, S. Adler, M. S. Atiya, I-H. Chiang

We have observed the rare decay K+ --> pi+ mu+ mu- and measured the branching ratio Gamma(K+ --> pi+ mu+ mu-)/Gamma(K+ --> all) = (5.0 +/- 0.4 (stat.) +/- 0.7 (sys.) +/- 0.6 (theor.)) x 10^{-8}. We compare this result with predictions from chiral perturbation theory and estimates based on the decay K+ --> pi+ e+ e-.

M. P. Nightingale, H. W. J. Bloete

Scaling behavior is studied of several dominant eigenvalues of spectra of Markov matrices and the associated correlation times governing critical slowing down in models in the universality class of the two-dimensional Ising model. A scheme is developed to optimize variational approximants of progressively rapid, independent relaxation modes. These approximan

R. R. Caldwell, Rahul Dave, Paul J. Steinhardt

We examine the possibility that a significant component of the energy density of the universe has an equation-of-state different from that of matter, radiation or cosmological constant ($Λ$). An example is a cosmic scalar field evolving in a potential, but our treatment is more general. Including this component alters cosmic evolution in a way that fits curr

Franz Embacher

Some basic ideas of the Refined Algebraic Quantization scheme are outlined at an intuitive level, using a class of simple models with a single wave equation as quantum constraint. In addition, hints are given how the scheme is applied to more sophisticated models, and it is tried to make transparent the general pattern characterizing this method.

P. Catelan, F. Lucchin, S. Matarrese, C. Porciani

This paper presents a stochastic approach to the clustering evolution of dark matter haloes in the Universe. Haloes, identified by a Press-Schechter-type algorithm in Lagrangian space, are described in terms of `counting fields&#39;, acting as non-linear operators on the underlying Gaussian density fluctuations. By ensemble averaging these counting fields, t

S. Bronoff, G. Dvali, K. Farakos, C. P. Korthals Altes

The physics of the Wilson line leads to new developments in high temperature particle physics. The main tool is the effective action for a given fixed value of the phase of the Wilson line. It furnishes a gauge invariant infrared cut off, and yields for small values of the phases a systematic procedure for obtaining a power series in the coupling g and glog(

Gysbert Zwart

We calculate the tadpole equations and their solutions for a class of four-dimensional orientifolds with orbifold group Z_N X Z_M, and we present the massless bosonic spectra of these models. Surprisingly we find no consistent solutions for the models with Z_2 X Z_4 and Z_4 X Z_4 orbifold groups.

Mark Hindmarsh, Photis Moulatsiotis

A particular class of variant axion models with two higgs doublets and a singlet is studied. In these models the axion couples either to the $u$-quark or $t$-quark or both, but not to $b$, $c$, $s$, or $d$. When the axion couples to only one quark the models possess the desirable feature of having no domain wall problem, which makes them viable candidates fo

J. L. F. Barbon, A. Pasquinucci

We consider in more detail the role of D0-branes as instantons in the construction of SU(N) Super Yang-Mills and Super QCD theories in four space-time dimensions with D4, D6 and NS-branes. In particular, we show how the D0-branes describe both the exact and constrained instantons and reproduce the correct pattern of lifting of zero modes on the various branc

H. Steck, M. Naraschewski, H. Wallis

We study the output properties of a pulsed atom laser consisting of an interacting Bose-Einstein condensate (BEC) in a magnetic trap and an additional rf field transferring atoms to an untrapped Zeeman sublevel. For weak output coupling we calculate the dynamics of the decaying condensate population, of its chemical potential and the velocity of the output a

J. P. B. C de Melo, T. Frederico, Lauro Tomio, A. E. Dorokhov

The electromagnetic tensor for inclusive electron scattering off the pion, ($W^{\mu\nu}$), for momentum transfers such that $q^+=0$, ($q^+=q^0+q^3$) is shown to obey a sum-rule for the component $W^{++}$. From this sum-rule, one can define the quark-antiquark correlation function in the pion, which characterizes the transverse distance distribution between t

Roberto Sacconi

We study numerically the region above the critical temperature of the four dimensional Random Field Ising Model. Using a cluster dynamic we measure the connected and disconnected magnetic susceptibility and the connected and disconnected overlap susceptibility. We use a bimodal distribution of the field with $ h_R=0.35T $ for all temperatures and a lattice s

B. M. Gammel

The rescaled range statistical analysis (R/S) is proposed as a new method to detect correlations in pseudorandom number generators used in Monte Carlo simulations. In an extensive test it is demonstrated that the RS analysis provides a very sensitive method to reveal hidden long run and short run correlations. Several widely used and also some recently propo

Shinji Hirano, Mitsuhiro Kato

Starting from the primal principle based on the noncommutative nature of (9+1)-dimensional spacetime, we construct a topologically twisted version of the supersymmetric reduced model with a certain modification. Our formulation automatically provides extra 1+1 dimensions, thereby the dimensions of spacetime are promoted to 10+2. With a suitable gauge choice,

J. O. Andersen

We study massless $g^2Φ^4$-theory at high temperature and with zero chemical potential. Using modern effective field theory methods,% recently developed by Braaten and Nieto, we derive the screening mass squared to order $g^5$. It is demonstrated that the result is renormalization group invariant to this order in the coupling constant. Renormalization group

Michal Horodecki, Pawel Horodecki

We analyse the problem of distillation of entanglement of mixed states in higher dimensional compound systems. Employing the positive maps method [M. Horodecki et al., Phys. Lett. A 223 1 (1996)] we introduce and analyse a criterion of separability which relates the structures of the total density matrix and its reductions. We show that any state violating t

E. Gotsman, E. M. Levin, U. Maor

We show how and why the small distance (&#34;hard&#34;) interaction, calculable in perturbative QCD, provides a mass cutoff in Gribov&#39;s formula for photon-proton collisions. This enables us to find a new and more restrictive bound for this process, $σ(γ^{*}p)\leq C(ln 1/x)^{5/2}$.A simple model the published experimental data over a wide range of photon

F. Delduc, L. Feher, L. Gallot

Subject to some conditions, the input data for the Drinfeld-Sokolov construction of KdV type hierarchies is a quadruplet $(\A,Λ, d_1, d_0)$, where the $d_i$ are $\Z$-gradations of a loop algebra $\A$ and $Λ\in \A$ is a semisimple element of nonzero $d_1$-grade. A new sufficient condition on the quadruplet under which the construction works is proposed and ex

Horia Scutaru

The fidelity for two displaced squeezed thermal states is computed using the fact that the corresponding density operators belong to the oscillator semigroup.

Weiqiang Wang

We show that the vertex algebra W{1+ \infty} with central charge -1 is isomorphic to a tensor product of the simple W_3 algebra with central charge -2 and a Heisenberg vertex algebra generated by a free bosonic field. We construct a family of irreducible modules of the W_3 algebra with central charge -2 in terms of free fields and calculate the full characte

K. -A. Suominen, Y. B. Band, I. Tuvi, K. Burnett

We derive and apply an optical Bloch equation (OBE) model for describing collisions of ground and excited laser cooled alkali atoms in the presence of near-resonant light. Typically these collisions lead to loss of atoms from traps. We compare the results obtained with a quantum mechanical complex potential treatment, semiclassical Landau-Zener models with d

J. C. J. Paasschens, M. J. M. de Jong, P. W. Brouwer, C. W. J. Beenakker

This is a theoretical study of the interplay of optical phase-conjugation and multiple scattering. We calculate the intensity of light reflected by a phase-conjugating mirror when it is placed behind a disordered medium. We compare the results of a fully phase-coherent theory with those from the theory of radiative transfer. Both methods are equivalent if th

Uwe E. Meier, Frank Demmig

A 2d unsteady bicharacteristic scheme with shock fitting is presented and its characteristic step, shock point step and boundary step are described. The bicharacteristic scheme is compared with an UNO scheme and the Moretti scheme. Its capabilities are illustrated by computing a converging, deformed shock wave.

Tomas Bohr, Vachtang Putkaradze, Shinya Watanabe

We present a simple viscous theory of free-surface flows in boundary layers, which can accommodate regions of separated flow. In particular this yields the structure of stationary hydraulic jumps, both in their circular and linear versions, as well as structures moving with a constant speed. Finally we show how the fundamental hydraulic concepts of subcritic

Ch. Elster, S. P. Weppner

The influence of the energy dependence of the free NN t-matrix on the optical potential of nucleon-nucleus elastic scattering is investigated within the context of a full-folding model based on the impulse approximation. The treatment of the pole structure of the NN t-matrix, which has to be taken into account when integrating to negative energies is describ

H. Merlitz, D. Pelte

The time dependent Schroedinger equation for two identical and charged pions is solved using wavepacket states. It is shown that the expected Coulomb distortion in the momentum correlation function is obliterated by the dispersion of the localized states, and therefore becomes unobservable.

W. T. H. van Oers, for E497 collaboration

Measurements of parity-violating longitudinal analyzing powers (normalized asymmetries) in polarized proton-proton scattering provide a unique window on the interplay between the weak and strong interactions between and within hadrons. Several new proton-proton parity violation experiments are presently either being performed or are being prepared for execut