May 1998 arXiv papers — page 7

A. Garcia, R. Huerta, G. Sanchez-Colon

Strong-flavor and parity a priori mixing in hadrons are shown to describe well the experimental evidence on weak radiative decays of hyperons. An independent determination of the a priori mixing angles is performed. The values obtained for them are seen to have a universality-like property, when compared to their values in non-leptonic decays of hyperons.

D. J. Miller, Michael H. Seymour

The multiplicity of heavy quarks from gluon splitting in e+e- annihilation has now been theoretically calculated and experimentally measured at LEP. However, the experimental measurement requires theoretical input for the shape of the multiplicity with respect to an event shape. In this paper we calculate the multiplicity of heavy quarks from gluon splitting

D. J. Miller, Michael H. Seymour

We calculate the average multiplicity of jets in e+e- annihilation as a function of both the jet resolution parameter, y_cut, and the thrust T. Our result resums to all orders the leading and next-to-leading logarithms in y_cut and 1-T, and is exact up to second order in alpha_s. This allows a comparison between the number of jets found using jet algorithms

Hongying Jin, X. M. Zhang

We examine the mixing between the sigma meson $σ$ and the "pure" glueball field $H$ and study the decays of the scalar glueball candidate $f_0(1500)$ (a linear combination of $σ$ and $H$) into two and four pions in effective linear sigma model. From recent experimental data on $f_0(1500)$ decay to pions we point out that the mixing angle is of order

S. M. Bilenky, C. Giunti, W. Grimus

We present a short review of the present status of the problem of neutrino masses and mixing. The existing experimental results indicate that there are at least four massive neutrinos. We show that only two schemes with mixing of four neutrinos and mass spectra in which two groups of close masses are separated by the ``LSND gap'' (~ 1 eV) are compati

Jian-Jun Yang, Guang-Lie Li

By means of the nuclear parton distributions which can be used to provide a good explanation for the EMC effect in the whole x range, we investigate the energy loss effect in nuclear Drell-Yan process. When the cross section of lepton pair production is considered varying with the center-of-mass energy of the nucleon-nucleon collision, we find that the nucle

Taku Izubuchi, Junichi Noaki, Akira Ukawa

We investigate the phase structure of the two-dimensional lattice Gross-Neveu model formulated with the Wilson fermion action to leading order of 1/N expansion. Structural change of the parity-broken phase under the influence of finite temperature and chemical potential is studied. The connection between the lattice phase structure and the chiral phase trans

The OPAL Collaboration, K. Ackerstaff et al

The production of K^0_S mesons and Lambda baryons in quark and gluon jets has been investigated using two complementary techniques. In the first approach, which provides high statistical accuracy, jets were selected using different jet finding algorithms and ordered according to their energy. Production rates were determined taking into account the dependenc

Henry T. Wong, Jin Li

A Collaboration comprising Taiwan and mainland Chinese scientists has been built up since 1996 to pursue a experimental program in neutrino and astro-particle physics in Taiwan. A pilot experiment to be performed at the Nuclear Power Station II in Taiwan is now under intense preparation. It will make use of a 600 kg CsI(Tl) crystal calorimeter to study vario

A. Arbona, C. Bona

Instabilities in finite difference codes due to the singularity of spherical coordinates at the center are studied. In typical Numerical Relativity applications, standard regularization techniques by themselves do not ensure long term stability. A proposal to remedy that problem is presented, which takes advantage of redundant quantities introduced in recent

L. N. Gyngazov, M. Pawlowski, V. N. Pervushin, V. I. Smirichinski

The paper is devoted to the description a measurable time-interval (``proper time'') in the Hamiltonian version of general relativity with the Dirac-ADM metric. To separate the dynamical parameter of evolution from the space metric we use the Lichnerowicz conformally invariant variables. In terms of these variables GR is equivalent to the conformally

A. Fabbri, J. Navarro-Salas

In this paper we address the issue of determining the semiclassical threshold for black hole formation in the context of a one-parameter family of theories which continuously interpolates between the RST and BPP models. We find that the results depend significantly on the initial static configuration of the spacetime geometry before the influx of matter is t

L. Mangiarotti, G. Sardanashvily

It is shown that any second order dynamic equation on a configuration space $X$ of non-relativistic time-dependent mechanics can be seen as a geodesic equation with respect to some (non-linear) connection on the tangent bundle $TX\to X$ of relativistic velocities. Using this fact, the relationship between relativistic and non-relativistic equations of motion

P. Raychaudhuri, C. Mitra, A. Paramekanti, R. Pinto

Bulk samples of La2.3-xYxCa0.7Mn2O7, x=0,0.3,0.5, with layered perovskite structure have been synthesized and investigated with respect to their electrical, electronic and magnetic properties. It is found that La1.8Y0.5Ca0.7Mn2O7 has tetragonal structure and is a metallic ferromagnet with a magnetic transition temperature of 170 K. The compound shows metalli

A. H. Castro Neto, A. V. Balatsky

We propose a mechanism for superconductivity suppression in stripe-correlated cuprates based on the pinning of the stripes by impurities, such as Zn. The suppression of superfluid density occurs in the vicinity of the impurity due to the low dimensional character of superfluid carriers on the stripes. Simple geometric argument about the planar fraction of th

Reinhold Egger, Hermann Grabert

The Landauer approach to transport in mesoscopic conductors has been generalized to allow for strong electronic correlations in a single-channel quantum wire. We describe in detail how to account for external voltage sources in adiabatic contact with a quantum wire containing a backscatterer of arbitrary strength. Assuming that the quantum wire is in the Lut

M. V. Voinova, M. Rodahl, M. Jonson, B. Kasemo

We have derived the general solution of a wave equation describing the dynamics of two-layere viscoelastic polymer materials of arbitrary thickness deposited on solid (quartz) surfaces in a fluid environment. Within the Voight model of viscoelastic element, we calculate the acoustic response of the system to an applied shear stress, i.e. we find the shift of

M. E. Cates, J. P. Wittmer

We describe a new continuum approach to the modelling of stress propagation in static granular media, focussing on the conical sandpile created from a point source. We argue that the stress continuity equations should be closed by means of scale-free, local constitutive relations between different components of the stress tensor, encoding the construction hi

James Rogers

Since the early Sixties and Seventies it has been known that the regular and context-free languages are characterized by definability in the monadic second-order theory of certain structures. More recently, these descriptive characterizations have been used to obtain complexity results for constraint- and principle-based theories of syntax and to provide a u

Edward L. Wright

The effect of a cosmological constant on the precession of the line of apsides is O(Λc^2 r^3/GM) which is 3(H_\circ P)^2/8π^2 \approx 10^{-23} for a vacuum-dominated Universe with Hubble constant H_\circ = 65 km/sec/Mpc and for the orbital period P = 88 days of Mercury. This is unmeasurably small, so planetary perturbations cannot be used to limit the cosmol

Kathryn V. Johnston, Steinn Sigurdsson, Lars Hernquist

We present the results of a study that uses numerical simulations to interpret observations of tidally disturbed satellites around the Milky Way. When analysing the simulations from the viewpoint of an observer, we find a break in the slope of the star count and velocity dispersion profiles in our models at the location where unbound stars dominate. We concl

Richard G. Bower, Tadayuki Kodama, Ale Terlevich

In this paper, we examine the role that the colour-magnitude relation (CMR) can play in constraining the formation history of rich cluster galaxies. Firstly, we consider the colour evolution of galaxies after star formation ceases. We show that the scatter of the CMR places a strong constraint on the spread in age of the bulk of the stellar population. Howev

Charles D. Dermer

A simple model for variability in relativistic plasma outflows is studied, in which nonthermal electrons are continuously and uniformly injected in the comoving frame over a time interval dt. The evolution of the electron distribution is assumed to be dominated by synchrotron losses, and the energy- and time-dependence of the synchrotron and synchrotron self

R. Rao, R. M. Crutcher, R. L. Plambeck, M. C. H. Wright

We present 1.3 and 3.3 mm polarization maps of Orion-KL obtained with the BIMA array at approximately 4 arcsec resolution. Thermal emission from magnetically aligned dust grains produces the polarization. Along the Orion ``ridge'' the polarization position angle varies smoothly from about 10 degrees to 40 degrees, in agreement with previous lower res

J. B. Jones, S. Phillipps, J. M. Schwartzenberg, Q. A. Parker

We present a study of the smallest and faintest galaxies found in a very deep photographic R band survey of two regions of the Virgo Cluster, totalling 3.2 square degrees, made with the UK Schmidt Telescope. The objects we detect have the same physical sizes and surface brightnesses as Local Group dwarf spheroidal galaxies. The luminosity function of these e

Ian A. Bonnell, Kester W. Smith, Michael R. Meyer, Christopher A. Tout

We present a method of determining lower limits on the masses of pre-main-sequence (PMS) stars and so constraining the PMS evolutionary tracks. This method uses the red-shifted absorption feature observed in some emission-line profiles of T Tauri stars indicative of infall. The maximum velocity of the accreting material measures the potential energy at the s

B. S. Sathyaprakash, Varun Sahni, Sergei F. Shandarin

We analyse shapes of overdense regions (clusters and superclusters) in controlled N-body simulations of gravitational clustering with power law initial spectra P(k) \propto k^n, n = -3, -2, -1, 0. At values of the density just above the percolation transition the number of distinct (isolated) clusters peaks and we use this `natural threshold' to study th

J. S. Gallagher, Eline Tolstoy, Robbie C. Dohm-Palmer, E. D. Skillman

The stellar population of the Pegasus dwarf irregular galaxy is investigated in images taken in the F439W (B), F555W (V), and F814W (I) bands with WFPC2. These and ground-based data are combined to produce color-magnitude diagrams which show the complex nature of the stellar population in this small galaxy. A young (< 0.5 Gyr) main sequence stellar component

Guinevere Kauffmann, Joerg M. Colberg, Antonaldo Diaferio, Simon D. M. White

We introduce a new technique for following the formation and evolution of galaxies in cosmological N-body simulations. Dissipationless simulations are used to track the formation and merging of dark matter halos as a function of redshift. Simple prescriptions, taken directly from semi-analytic models of galaxy formation, are adopted for cooling, star formati

Neil Trentham, Bahram Mobasher

We present the K-band (2.2 microns) luminosity functions of the X-ray luminous clusters MS1054-0321 (z=0.82), MS0451-0305 (z=0.55), Abell 963 (z=0.206), Abell 665 (z=0.182) and Abell 1795 (z=0.063) down to absolute magnitudes M_K = -20. Our measurements probe fainte absolute magnitudes than do any previous studies of the near-infrared luminosity function of

R. De Propris, C. Pritchet

We derive $I$ band luminosity functions for galaxies in Abell 426 (Perseus and Abell 539, two rich, low galactic latitude clusters at moderate redshift. Cluster members are selected via the color-magnitude relation for bright galaxies. We find $α=-1.56 \pm 0.07$ for Perseus over the range $-19.4 < M_I < -13.4$ ($15 < I < 21$) and $α=-1.42 \pm 0.14$ for $-18.

Eric W. Deutsch, Bruce Margon, Scott F. Anderson

We examine images of the field of X1832-330, the luminous (Lx ~ 10^36 erg/s) X-ray burst source near the center of the globular cluster NGC 6652, in order to identify the optical counterpart for further study. U and B ground-based images allow us to set a limit M_B > 3.5 for the counterpart at the time of those observations, provided that the color is (U-B)_

E. Sezgin, P. Sundell

The product of two N=8 supersingletons yields an infinite tower of massless states of higher spin in four dimensional anti de Sitter space. All the states with spin s > 1/2 correspond to generators of Vasiliev's super higher spin algebra shs^E (8|4) which contains the D=4, N=8 anti de Sitter superalgebra OSp(8|4). Gauging the higher spin algebra and introduc

Yu. B. Khavin, M. E. Gershenson, A. L. Bogdanov

We report on the experimental study of electron transport in sub-micron-wide &#39;&#39;wires&#39;&#39; fabricated from Si $δ$-doped GaAs. These quasi-one-dimensional (Q1D) conductors demonstrate the crossover from weak to strong localization with decreasing the temperature. On the insulating side of the crossover, the resistance has been measured as a functi

Claudio Coriano, Hsiang-nan Li, Cetin Savkli

Experiments at CEBAF will scan the intermediate-energy region of the QCD dynamics for the nucleon form factors and for Compton Scattering. These experiments will definitely clarify the role of resummed perturbation theory and of quark-hadron duality (QCD sum rules) in this regime. With this perspective in mind, we review the factorization theorem of perturba

Erich Holtmann, M. Kawasaki, K. Kohri, Takeo Moroi

The effects of radiatively decaying, long-lived particles on big-bang nucleosynthesis (BBN) are discussed. If high-energy photons are emitted after BBN, they may change the abundances of the light elements through photodissociation processes, which may result in a significant discrepancy between the BBN theory and observation. We calculate the abundances of

David J. Gross, Hirosi Ooguri

In this paper we explore some of the features of large N supersymmetric and nonsupersymmetric gauge theories using Maldacena&#39;s duality conjectures. We shall show that the resulting strong coupling behavior of the gauge theories is consistent with our qualitative expectations of these theories. Some of these consistency checks are highly nontrivial and gi

Vibhat Nair, Jordi Miralda-Escude

A large number of microlensing events have been observed in the direction of the Galactic bulge, with a measured optical depth in the range 2 - 3 x 10^{-6}. It has been shown that most of these events are due to bulge stars being lensed by other bulge stars or by foreground disk stars. Among the stars observed in the bulge fields, there should also be disk s

Qimiao Si, C. M. Varma

We calculate the corrections to the conductivity and compressibility of a disordered metal when the mean free path is smaller than the screening length. Such a condition is shown to be realized for low densities and large disorder. Analysis of the stability of the metallic state reveals a transition to the insulating state in two-dimensions.

T. A. Arias

This article reviews recent developments in multiresolution analysis which make it a powerful tool for the systematic treatment of the multiple length-scales inherent in the electronic structure of matter. Although the article focuses on electronic structure, the advances described are useful for non-linear problems in the physical sciences in general. The n

H. R. Christiansen, M. S. Cunha, J. A. Helayel-Neto, L. R. U. Manssur

We find self-dual vortex solutions in a Maxwell-Chern-Simons model with anomalous magnetic moment. From a recently developed N=2-supersymmetric extension, we obtain the proper Bogomol&#39;nyi equations together with a Higgs potential allowing both topological and non-topological phases in the theory.

David Tsiklauri, Raoul D. Viollier

It is shown that the matter concentration observed through stellar motion at the galactic center (Eckart & Genzel, 1997, MNRAS, 284, 576 and Genzel et al., 1996, ApJ, 472, 153) is consistent with a supermassive object of $2.5 \times 10^6$ solar masses composed of self-gravitating, degenerate heavy neutrinos, as an alternative to the black hole interpretation

David Tsiklauri, Raoul D. Viollier

It has been recently shown (Tsiklauri & Viollier, 1998a) that the matter concentration inferred from observed stellar motion at the galactic center (Eckart & Genzel, 1997, MNRAS, 284, 576 and Genzel et al., 1996, ApJ, 472, 153) is consistent with a supermassive object of $2.5 \times 10^6$ solar masses, composed of self-gravitating, degenerate heavy neutrinos

David Tsiklauri

Criterion of the Jeans instability of interstellar gas clouds which are gravitationally coupled with weakly interacting massive particles is revisited. It is established that presence of the dark matter always reduces the Jeans length, and in turn, Jeans mass of the interstellar gas clouds. Astrophysical implications of this effect are discussed.

Jose A. Font, Jose M. Ibanez, Philippos Papadopoulos

We present a new geometrical approach to the study of accretion flows onto rotating (Kerr) black holes. Instead of Boyer-Lindquist coordinates, the standard choice in all existing numerical simulations in the literature, we employ the simplest example of a horizon adapted coordinate system, the Kerr-Schild coordinates. This choice eliminates boundary ambigui

Jiro Arafune, Yukihiro Mimura

The multi-body neutrino potential energy is analytically estimated for a spherical neutron star with a vector potential model for neutrinos. We show that the self-energy and the neutrino number of the neutron star coincide with the semi-classical values in the large volume limit, and confirm that there is no catastrophe in neutron stars with massless neutrin

A. Zapletal

The quantized version of a discrete Knizhnik-Zamolodchikov system is solved by an extension of the generalized Bethe Ansatz. The solutions are constructed to be of highest weight which means they fully reflect the internal quantum group symmetry.

M. Henon, J-M. Petit

Numerical integrations in celestial mechanics often involve the repeated computation of a rotation with a constant angle. A direct evaluation of these rotations yields a linear drift of the distance to the origin. This is due to roundoff in the representation of the sine s and cosine c of the angle theta. In a computer, one generally gets c^2 + s^2 <> 1, res

M. M. Rieger, L. Steinbeck, I. D. White, H. N. Rojas

We present a detailed account of the GW space-time method. The method increases the size of systems whose electronic structure can be studied with a computational implementation of Hedin&#39;s GW approximation. At the heart of the method is a representation of the Green&#39;s function G and the screened Coulomb interaction W in the real-space and imaginary-t

Jan-e Alam, Sourav Sarkar, Pradip Roy, Binayak Dutta-Roy

Unstable particles (such as the vector mesons) have an important role to play in low mass dilepton production resulting from heavy ion collisions and this has been a subject of several investigations. Yet subtleties, such as the implications of the generalization of the Breit-Wigner formula for nonzero temperature and density, e.g. the question of collisiona

Kamiokande Collaboration, Y. Fukuda et al

The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. The results shown here are obtained from data taken between the 31st of May, 1996, and the 23rd of June, 1997. Using our measurement of recoil electrons with energies above 6.5 MeV, we infer the total flux of 8B solar neutrinos to be 2.42+-0.06(stat.)+0.10-0.07(syst

Goetz S. Uhrig, Friedhelm Schoenfeld, Markus Laukamp, Elbio Dagotto

A quantum mechanical picture is presented to describe the behavior of confined spinons in a variety of S=1/2 chains. The confinement is due to dimerization and frustration and it manifests itselfas a nonlinear potential V(x)~ |x|^b, centered at chain ends (b <= 1) or produced by modulation kinks (b > 1). The calculation extends to weak or zero frustration so

Tomonori Totani

Brightness distribution of Gamma-Ray Bursts (GRBs) is studied in detail under the assumption that GRB rate is related to cosmic star formation rate. The two populations of the long- and short-duration bursts in the 4B BATSE catalog are analyzed separately. Taking account of current uncertainties in the observational estimate of star formation rate (SFR), we

B. Sathiapalan

We use the Matrix formalism to investigate what happens to strings above the Hagedorn temperaure. We show that it is not a limiting temperature but a temperature at which the continuum string picture breaks down. We study a collection of $N$ D-0-branes arranged to form a string having $N$ units of light cone momentum. We find that at high temperatures the fa

H. Anlauf, A. B. Arbuzov, E. A. Kuraev, N. P. Merenkov

The leading and next-to-leading radiative corrections to deep inelastic events with tagged photons are calculated analytically. Comparisons with previous results and numerical estimations are presented for the experimental conditions at HERA.

Manuel Manas, Luis Martinez Alonso

We show how Ramond free neutral Fermi fields lead to a $τ$-function theory of BKP type which describes iso-orthogonal deformations of systems of ortogonal curvilinear coordinates. We also provide a vertex operator representation for the classical Ribaucour transformation.

Roberto Onofrio, Lorenza Viola

The Lindblad approach to continuous quantum measurements is applied to a system composed of a two-level atom interacting with a stationary quantized electromagnetic field through a dispersive coupling fulfilling quantum nondemolition criteria. Two schemes of measurements are examined. The first one consists in measuring the atomic electric dipole, which indi

Haiqing Wei, Xin Xue, S. D. Morgera

In a lattice ${\cal L}$ of nuclear spins with ABCABCABC... type periodic structure embedded in a single-crystal solid, each ABC-unit can be used to store quantum information and the information can be moved around via some cellular shifting mechanism. Impurity doping marks a special site D$\not\in{\cal L}$ which together with the local spin lattice constitut

Thomas L. Beck

A method for performing high order mesh refinement multigrid computations is presented. The Full Approximation Scheme (FAS) multigrid technique is utilized for a sequence of nested patches of increasing resolution. Conservation forms are generated on coarse scales by additional defect correction terms which counter the local excess fluxes at the boundaries.

F. Krmpotic, E. J. V. de Passos, D. S. Delion, J. Dukelsky

Self Consistent Quasiparticle Random Phase Approximation (SCQRPA) is considered in application to the Fermi transitions within the O(5) model. It is demonstrated that SCQRPA improves on renormalized QRPA (RQRPA), a method that has recently become rather popular in this context. The analytical form of the SCQRPA vacuum is used to evaluate all the matrix eleme

I. Zakout, H. R. Jaqaman

The Quark Meson Coupling Model which describes nuclear matter as a collection of non-overlapping MIT bags interacting by the self-consistent exchange of scalar and vector mesons is used to study nuclear matter at finite temperature. In its modified version, the density dependence of the bag constant is introduced by a direct coupling between the bag constant

H. Shen, H. Toki, K. Oyamatsu, K. Sumiyoshi

We construct the equation of state (EOS) of nuclear matter using the relativistic mean field (RMF) theory in the wide density, temperature range with various proton fractions for the use of supernova simulation and the neutron star calculations. We first construct the EOS of homogeneous nuclear matter. We use then the Thomas-Fermi approximation to describe i

P. Mohr, H. Beer, H. Oberhummer, G. Staudt

The neutron capture cross section of 26Mg was measured relative to the known gold cross section at thermonuclear energies using the fast cyclic activation technique. The experiment was performed at the 3.75 MV Van-de-Graaff accelerator, Forschungszentrum Karlsruhe. The experimental capture cross section is the sum of resonant and direct contributions. For th

P. Collet, J. -P. Eckmann

We define the topological entropy per unit volume in parabolic PDE&#39;s such as the complex Ginzburg-Landau equation, and show that it exists, and is bounded by the upper Hausdorff dimension times the maximal expansion rate. We then give a constructive implementation of a bound on the inertial range of such equations. Using this bound, we are able to propos

Theodore B. Stanford

We show that two knots have matching Vassiliev invariants of order less than n if and only if they are equivalent modulo the nth group of the lower central series of some pure braid group, thus characterizing Vassiliev&#39;s knot invariants in terms of the structure of the braid groups. We also prove some results about knots modulo the nth derived subgroups

János Kollár

Let $f_i$ be polynomials in $n$ variables without a common zero. Hilbert&#39;s Nullstellensatz says that there are polynomials $g_i$ such that $\sum g_if_i=1$. The effective versions of this result bound the degrees of the $g_i$ in terms of the degrees of the $f_j$. The aim of this paper is to generalize this to the case when the $f_i$ are replaced by arbitr

Mirko Primc

By using the Kang-Kashiwara-Misra-Miwa-Nakashima-Nakayashiki crystal base character formula for the basic $A_2^{(1)}$-module, and the principally specialized Weyl-Kac character formula, we obtain a Rogers-Ramanujan type combinatorial identity for colored partitions. The difference conditions between parts are given by the energy function of certain perfect $

Claude Sabbah

We show that, given a projective regular function f on a smooth quasi-projective variety over C, the corresponding cohomology groups of the algebraic de Rham complex with twisted differential d-df and of the complex of algebraic forms with differential df have the same dimension (a result announced by Barannikov and Kontsevitch). We generalize the result to

Andras Nemethi, Claude Sabbah

We prove that, for an analytic family of ``weakly tame&#39;&#39; regular functions on an affine manifold, the spectrum at infinity of each function of the family is semicontinuous in the sense of Varchenko.

A. Kishimoto, A. Kumjian

Let A be a simple unital AT algebra of real rank zero and Inn(A) the group of inner automorphisms of A. In the previous paper we have shown that the natural map of the group of approximately inner automorphisms into Ext(K_1(A),K_0(A)) oplus Ext(K_0(A),K_1(A)) is surjective; the kernel of this map includes the subgroup of automorphisms which are homotopic to

A. Kehagias

We discuss a D3-D7 system in type IIB string theory. The near-horizon geometry is described by AdS^5 x X^5 where X^5 is a U(1) bundle over a Kahler-Einstein complex surface S with positive first Chern class c_1>0. The surface S can either be P^1 x P^1, P^2 or P_{n_1,...,n_k}, a blow up of P^2 at k points with 3\leq k\leq 8. The P^2 corresponds to the maximal

C. D. Fosco, J. C. Le Guillou

We construct transformations that decouple fermionic fields in interaction with a gauge field, in the path integral representation of the generating functional. Those transformations express the original fermionic fields in terms of non-interacting ones, through non-local functionals depending on the gauge field. This procedure, holding true in any number of

C. R. Preitschopf, M. A. Vasiliev

We formulate classical actions for N=1 supergravity in D=(1,3) as a gauge theory of OSp(1|4). One may choose the action such that it does not include a cosmological term.

F. Pisano, J. A. Silva-Sobrinho, M. D. Tonasse

We consider the contributions of the exotic quarks and gauge bosons to the mass difference between the short- and the long-lived neutral kaon states in $SU(3)_C \times SU(3)_L \times U(1)_N$ model. The lower bound $M_{Z&#39;} \sim$ 14 TeV is obtained for the extra neutral gauge boson ${Z&#39;}^0$. Ranges for values of one of the exotic quark masses and quark

Benjamin Grinstein, Richard F. Lebed

We compare the effects of different quark diagram topologies on the weak hadronic width of heavy-light mesons in the large N_c limit. We enumerate the various topologies and show that the only one dominant (or even comparable) in powers of N_c to the noninteracting spectator &#34;tree&#34; diagram is the &#34;annihilation&#34; diagram, in which the valence q

A. Ali, G. Kramer, C. D. Lu

We present estimates of the direct (in decay amplitudes) and indirect (mixing- induced) CP-violating asymmetries in the non-leptonic charmless two-body decay rates for $B \to PP$, $B \to PV$ and $B \to VV$ decays and their charged conjugates, where P(V) is a light pseudoscalar (vector) meson. These estimates are based on a generalized factorization approach

P. H. Frampton, X. Guan

There are serious discussions for building a muon collider with $μ^{+}μ^{-}$ collisions at c.o.m. energies up to 4 TeV. We point out that the bileptonic gauge bosons predicted in some extensions of the Standard Model would be readily discernable from the backward scattering cross-section, for bilepton masses up to a substantial fraction of the c.o.m. energy.

R. D. Dikeman

The full treatment, both nonperturbative - through O(1/m_c^3) - and perturbative - through O(alpha_s) and BLM type O(alpha_s^2) - of the semileptonic lifetime of the D meson is given. A dedicated discussion of the numerics involved is made, with the result that the leading order prediction plus corrections fail to match experiment. To explain the difference,

G. Raffelt

If axions exist, they are copiously produced in hot and dense plasmas, carrying away energy directly from the interior of stars. Various astronomical observables constrain the operation of such anomalous stellar energy-loss channels and thus provide restrictive limits on the axion interactions with photons, nucleons, and electrons. In typical axion models a

M. Masip, R. Munoz-Tapia

We study the limits on the mass of the lightest Higgs in supersymmetric models extended with a gauge singlet when perturbative unification is required. We find that when maximum intermediate matter is added, the different evolution of the gauge couplings raises the mass bound from 135 GeV to 155 GeV. In these models perturbative unification of the gauge coup

Neven Bilic, David Tsiklauri, Raoul Viollier

In the framework of the Thomas-Fermi model at finite temperature, we show that a cooling nondegenerate gas of massive neutrinos will undergo a phase transition in which quasi-degenerate supermassive neutrino stars are formed through gravitational collapse. For neutrinos in the mass range of 10 to 25 keV these compact dark objects could mimic the role of supe

Y. Kawamura, H. P. Nilles, M. Olechowski, M. Yamaguchi

The relic abundance of stable neutralinos is investigated in $E_8 \times E_8'$ heterotic string theory when supersymmetry is spontaneously broken by hidden-sector gaugino condensates. In the weak coupling regime, very large scalar masses (compared to gaugino masses) are shown to lead to a too large relic abundance of the neutralinos, incompatible with cosmol

M. A. Braun

A review is made of the odderon idea in high-energy physics, complemented by an outline of the recent calculations of the odderon properties in the perturbative QCD.

G. Hellstern, M. Oettel, R. Alkofer, H. Reinhardt

In a covariant model where constituent quarks and diquarks interact through quark exchange, the Bethe-Salpeter equation in ladder approximation for octet and decuplet baryons is solved. Quark and diquark confinement is thereby effectively parametrised by choosing appropriately modified propagators. Numerical results for the baryon masses are presented. In a

Daniel Wicke

The size of non-perturbative corrections to event shape observables is predicted to fall like powers of the inverse centre of mass energy. These power corrections are investigated for different observables from $e^+e^-$-annihilation measured at LEP as well as previous experiments. The obtained corrections are compared to other approaches and theoretical pred

Feng-Cai Ma, Hai-Ming Hu

A testing of quantum mechanics in nuetrino oscillation is presented. The quantum mechanics violation motivated by arguements of quantum gravity is investigated in neutrino system. The formula of density matrix and oscillation probability of nuetrinos with and without the effect of quantum mechanics violation are derived for the cases of neutrino ocsillation

B. A. Kniehl, A. Sirlin

The differences between the on-shell mass and width of the Higgs boson and their pole counterparts are evaluated in leading order. For a heavy Higgs boson, they are found to be sensitive functions of the gauge parameter and become numerically large over a class of gauges that includes the unitary gauge. For a light Higgs boson, the differences remain small i

J. Bijnens, G. Colangelo, P. Talavera

We calculate the vector and scalar form factors of the pion to two loops in Chiral Perturbation Theory. We estimate the unknown O(p^6) constants using resonance exchange. We make a careful comparison to the available data and determine two O(p^4) constants rather precisely, and two O(p^6) constants less precisely. We also use Chiral Perturbation Theory to tw

U. Nierste

Direct CP-asymmetries in inclusive decay modes can be cleanly calculated by exploiting quark-hadron duality. This is in sharp contrast to CP-asymmetries in exclusive channels, where unknown strong phases prevent a clean extraction of CKM parameters from measured CP-asymmetries. We have calculated the inclusive CP-asymmetries in B^{+/-}-decays into charmless

S. M. Bilenky, C. Giunti, W. Grimus

We consider the two schemes with four massive neutrinos which are compatible with the results of all neutrino oscillation experiments. We show that in these two schemes the probabilities of nu_e disappearance and nu_mu->nu_e appearance in long-baseline experiments are strongly suppressed.

T. Teshima, T. Sakai

We analyzed the atmospheric neutrino experiments of SuperKamiokande including zenith angle dependence&#39;s using the three-flavor neutrino framework with the hierarchy m^2_1 \approx m^2_2<<m^2_3. Taking into account the terrestrial, solar neutrino experimental data and the atmospheric neutrino experiments including the sub-GeV and multi-GeV data in SuperKam

O. K. Kalashnikov

The one-particle electron spectrum is found for hot and dense QED and its properties are investigated in comparison with the collective spectrum. It is shown that the one-particle spectrum (in any case its zero momentum limit) is gauge invariant, but the collective spectrum, being qualitatively different, is always gauge dependent. The exception is the case

D. Cormier

For simple inflationary models, we provide a consistent and complete scheme by which the macro-physical details of early universe inflation may be determined explicitly from the underlying micro-physical theory. We examine inflationary dynamics within the context of a fully renormalized, non-perturbative, and non-equilibrium quantum field theory using the cl

K. Splittorff, A. D. Jackson

A chiral random matrix model with locality is constructed and examined. The Nielsen-Ninomiya no-go theorem is circumvented by the use of a generally applicable modified Dirac operator which respects the Ginsparg-Wilson relation. We observe the expected universal behaviour of the eigenvalue density in the microscopic limit.

K. Abe et al

We present an improved comparison of the strong coupling of the gluon to light (q_l=u+d+s), c, and b quarks, determined from multijet rates in flavor-tagged samples of hadronic Z0 decays recorded with the SLC Large Detector at the SLAC Linear Collider between 1993 and 1995. Flavor separation among primary q_l q_l-bar, c c-bar, and b b-bar final states was ma

Stephane Willocq

We report new preliminary B Physics results obtained with 300,000 hadronic Z0 decays collected by the SLD experiment at the SLC between 1993 and 1997. Three analyses are presented: a measurement of B+ and B0 lifetimes, a study of the time dependence of Bs - Bs-bar mixing, and a search for decays of the type b --> sg. All analyses benefit from the small and s

Alberto Saa, Marcelo Schiffer

In this essay we show that an uncharged black-hole moving superluminally in a transparent dielectric medium violates Hawking&#39;s area theorem. The violation is overcome through the emission of radiation. Since modes cannot emerge from the black hole itself, this radiation must originate from a collective effect in the medium, in complete analogy with the V

G. &#39;t Hooft

Trans-Planckian particles are elementary particles accelerated such that their energies surpass the Planck value. There are several reasons to believe that trans-Planckian particles do not represent independent degrees of freedom in Hilbert space, but they are controlled by the cis-Planckian particles. A way to learn more about the mechanisms at work here, i

J. Podolsky, K. Vesely

We demonstrate chaotic behavior of timelike, null and spacelike geodesics in non-homogeneous vacuum pp-wave solutions. This seems to be the first known example of a chaotic motion in exact radiative spacetime.

Lajos Diosi

The calculations of Guang-Wen Ma&#39;s recent Letter [Phys.Lett. A239, (1998) 209] contain an easily detectable error which makes his conclusions irrelevant.