July 1998 arXiv papers — page 7

Tadatomi Shinohara, Hajime Tanaka, Ikuo S. Sogami

Hypotheses of the universal seesaw mechanism and the {\it universal strength for Yukawa couplings} are applied to explain one possible origin of quasi-democratic mass matrices of a special type in a left-right symmetric model with the gauge group $SU(3)_c\times SU(2)_L\times SU(2)_R\times U(1)$. Two kinds of Higgs doublets are postulated to mediate scalar in

Lian-You Shan

An Aoki-Denner form of the renormalization scheme is suggested for the physical amplitudes in MSSM. The Higgs sector is reparameterized with the mass of the CP odd scalar, and the mass of the heavy CP even one instead of $tanβ$ in our scheme. The counterterms of $tanβ$ is fixed perturbatively on mass shell just within Higgs sector. The counterterms of gauge-

Kenji Suzuki

We have proposed the entropy formula of the black hole which is constructed by the intersecting D1-brane and D5-brane with no momentum, whose compactification radii are constrained by the surface gravities in ten-dimensions. We interpret the entropy of the black hole as the statistical entropy of the effective string living on the D5-brane. We further study

Tae-Sun Park, Kuniharu Kubodera, Dong-Pil Min, Mannque Rho

We show how effectively effective quantum field theories work in nuclear physics. Using the physically transparent cut-off regularization, we study the simplest nuclear systems of two nucleons for both bound and scattering states at a momentum scale much less than the pion mass. We consider all the static properties of the deuteron, the two-nucleon scatterin

H. J. S. Dorren

We investigate the integrability of Nonlinear Partial Differential Equations (NPDEs). The concepts are developed by firstly discussing the integrability of the KdV equation. We proceed by generalizing the ideas introduced for the KdV equation to other NPDEs. The method is based upon a linearization principle which can be applied on nonlinearities which have

Markus Pueschel, Martin Roetteler, Thomas Beth

An algorithm is presented allowing the construction of fast Fourier transforms for any solvable group on a classical computer. The special structure of the recursion formula being the core of this algorithm makes it a good starting point to obtain systematically fast Fourier transforms for solvable groups on a quantum computer. The inherent structure of the

H. Gisin, J. Brendel, H. Zbinden, A. Sergienko

The potential of twin photons generated by parametric down-conversion for metrological applications are discussed. We present several experimental results like the measurement of chromatic dispersion and polarization mode dispersion in optical fibers.

G. Chabrier, A. Y. Potekhin

Thermodynamic quantities of Coulomb plasmas consisting of point-like ions immersed in a compressible, polarizable electron background are calculated for ion charges Z=1 to 26 and for a wide domain of plasma parameters ranging from the Debye-Hueckel limit to the crystallization point and from the region of nondegenerate to fully degenerate nonrelativistic or

M. Ferrario, L. Serafini

Free Electron Lasers driven by Super-Conducting Linacs require the generation, acceleration and transport of trains of bunches with high charge, high repetition rate and low emittance. A numerical model already developed for the modeling of beam dynamics in SC Linacs has been now extended to treat RF guns with proper description of the photocathode bunch gen

S. Beirle, U. Werthenbach, G. Zech, T. Zeuner

Gas electron multipliers (GEMs) have been overcoated with a high resistivity 10e14 - 10e15 Ohms / square amorphous carbon layer. The coating avoids charging up of the holes and provides a constant gain immediately after switching on independent of the rate. The gain uniformity across the GEM is improved. Coating opens the possibility to produce thick GEMs of

D. Chruscinski, J. Kijowski

New, gauge-independent, second-order Lagrangian for the motion of classical, charged test particles is proposed. It differs from the standard, gauge-dependent, first order Lagrangian by boundary terms only. A new method of deriving equations of motion from field equations is developed. When applied to classical electrodynamics, this method enables us to obta

J. A. Richmond, S. Nic Chormaic, B. P. Cantwell, G. I. Opat

We propose a novel method for guiding cold, neutral atoms using static magnetic fields. A theoretical study of the magnetic field produced by a tube consisting of two identical, interwound solenoids carrying equal but opposite currents is presented. This field is almost zero throughout the centre of the tube, but it increases with exponential rapidity as one

Bernhard Haisch, Alfonso Rueda, H. E. Puthoff

A NASA-funded research effort has been underway at the Lockheed Martin Advanced Technology Center in Palo Alto and at California State University in Long Beach to develop and test a recently published theory that Newton's equation of motion can be derived from Maxwell's equations of electrodynamics as applied to the zero-point field (ZPF) of the quan

G. J. Stephenson,, T. Goldman

Scalar or right-chiral interaction currents may be expected to produce a neutrino coupled to the electron which is different from, and perhaps even orthogonal to, that coupled to the electron by the standard model weak interaction. We show that, using reasonable parameter values for such additional interactions, it is possible to generate a spectrum which, i

Frederick T. Hawes, Pieter Maris, Craig D. Roberts

We elucidate constraints imposed by confinement and dynamical chiral symmetry breaking on the infrared behaviour of the dressed-quark and -gluon propagators, and dressed-quark-gluon vertex. In covariant gauges the dressing of the gluon propagator is completely specified by P(k^2):= 1/[1+Pi(k^2)], where Pi(k^2) is the vacuum polarisation. In the absence of pa

Elvira Biasioli, Marco Traini, Renzo Leonardi

We study the response of the nucleon, as a system of three bound (constituent) non relativistic quarks, to external (quasi static) electric and magnetic fields. The approach, based on a sum rule technique, is applied to a large class of two and three-body interquark potentials. Lower and upper bounds to the electric polarizability and para-magnetic susceptib

Rainer Verch

The investigation of wavefront sets of n-point distributions in quantum field theory has recently acquired some attention stimulated by results obtained with the help of concepts from microlocal analysis in quantum field theory in curved spacetime. In the present paper, the notion of wavefront set of a distribution is generalized so as to be applicable to st

Shinar Kouranbaeva

Misiolek has shown that the Camassa-Holm (CH) equation is a geodesic flow on the Bott-Virasoro group. In this paper it is shown that the Camassa-Holm equation for the case $κ=0$ is the geodesic spray of the weak Riemannian metric on the diffeomorphism group of the line or the circle obtained by right translating the $H^1$ inner product over the entire group.

Hasan R. Karadayi

We show that a specialization in Weyl character formula can be carried out in such a way that its right-hand side becomes simply a Schur Function. For this, we need the use of fundamental weights. In the generic definition, an Elementary Schur Function $S_Q(x_1,x_2,..,x_Q)$ of degree Q is known to be defined by some polynomial of Q indeterminates $ x_1,x_2,.

Tevian Dray, Corinne A. Manogue

We discuss the eigenvalue problem for 2x2 and 3x3 octonionic Hermitian matrices. In both cases, we give the general solution for real eigenvalues, and we show there are also solutions with non-real eigenvalues.

George E. Andrews, Anne Schilling, S. Ole Warnaar

Using new $q$-functions recently introduced by Hatayama et al. and by (two of) the authors, we obtain an A_2 version of the classical Bailey lemma. We apply our result, which is distinct from the A_2 Bailey lemma of Milne and Lilly, to derive Rogers-Ramanujan-type identities for characters of the W_3 algebra.

Do Ngoc Diep

This research notes is intended to provide a quick introduction to the subject. We expose a K-theoretic approach to study group C*-algebras: started in the elementary part, with one example of description of the structure of C*-algebras of the group of affine transformations of the real straight line, continued then for special classes of solvable and nilpot

P. P. Kulish, V. D. Lyakhovsky

The limiting transitions between different types of quantizations are studied by the deformation theory methods. We prove that for the first order coboundary deformation (g,g*_1 + x g*_2) of a Lie bialgebra (g,g*) one can always get the quantized Lie bialgebra (g,g*_2) as a limit of the sequence of quantizations of the type A(g,g*_1). The obtained results ar

Daniel Hershkowitz, Michael Neumann, Hans Schneider

We show that a matrix is a Hermitian positive semidefinite matrix whose nonzero entries have modulus 1 if and only if it similar to a direct sum of all $1's$ matrices and a 0 matrix via a unitary monomial similarity. In particular, the only such nonsingular matrix is the identity matrix and the only such irreducible matrix is similar to an all 1's ma

George Chapline

Recent hints from observations of distant supernovae of a positive cosmological constant with magnitude comparable to the average density of matter seem to point in the direction of a two fluid model for spacetime; where the "normal" component consists of ordinary matter, while the "superfluid" component is a zero entropy condensate. Such a t

George Siopsis

We discuss non-relativistic scattering by a Newtonian potential. We show that the gray-body factors associated with scattering by a black hole exhibit the same functional dependence as scattering amplitudes in the Newtonian limit, which should be the weak-field limit of any quantum theory of gravity. This behavior arises independently of the presence of supe

Duiliu-Emanuel Diaconescu, Rami Entin

Five dimensional field theories with exceptional gauge groups are engineered from degenerations of Calabi-Yau threefolds. The structure of the Coulomb branch is analyzed in terms of relative Kähler cones. For low number of flavors, the geometric construction leads to new five dimensional fixed points.

Yves Brihaye, Betti Hartmann, Jutta Kunz

We study static spherically symmetric gravitating dyon solutions and dyonic black holes in Einstein-Yang-Mills-Higgs theory. The gravitating dyon solutions share many features with the gravitating monopole solutions. In particular, gravitating dyon solutions and dyonic black holes exist up to a maximal coupling constant, and beside the fundamental dyon solut

Manu Mathur

Recently Faddeev and Niemi proposed a low energy effective action for pure SU(2) Yang Mills theory in 4 dimension to describe its long distance physics. The effective action is O(3) $σ$ model with a mass parameter, a dimensionless coupling constant e and a topological term. In this work, choosing a new set of variables, we relate this $σ$ model to a U(1) gau

Minoru Wakimoto

In this note we calculate the fusion coefficients for minimal series representations of the N=2 superconformal algebra by using a modified Verlinde's formula, and obtain associative and commutative fusion algebras with non-negative integral fusion coefficients at each level. Some references are added.

Bogdan A. Dobrescu, Elizabeth H. Simmons

We present a model of dynamical electroweak symmetry breaking in which the splitting between the top and bottom quark masses arises naturally. The W and Z masses are produced by a minimal technicolor sector, the top quark mass is given by the exchange of a weak-doublet technicolored scalar, and the other quark and lepton masses are induced by the exchange of

K. Zuber

The current status of neutrino oscillation searches with reactors and accelerators is reviewed. An outlook, especially on future long baseline neutrino oscillation projects, is given.

Romuald A. Janik, Maciej A. Nowak, Gabor Papp, Ismail Zahed

We give a pedagogical introduction to the concept that light quarks diffuse in the QCD vacuum following the spontaneous breaking of chiral symmetry. By analogy with disordered electrons in metals, we show that the diffusion constant for light quarks in QCD is $D=2F_π^2/|\la\bar{q}q\to|$ which is about 0.22 fm. We comment on the correspondence between the dif

Utpal Sarkar

A simple model to accomodate light sterile neutrinos naturally with large mixing with the usual neutrinos has been proposed. The standard model gauge group is extended to include an $SU(2)_S$ gauge symmetry. Heavy triplet higgs scalars give small masses to the left-handed neutrinos, while a heavy doublet higgs scalar give mixing with the sterile neutrinos of

G. Montagna, M. Moretti, O. Nicrosini, F. Piccinini

The search for new physics in single- and multi-photon final states with large missing energy at LEP and future e^+ e^- colliders requires precise predictions for the Standard Model irreducible background. While at LEP1 the theoretical situation is under control, going to LEP2 (and beyond) some improvements are necessary. To approach the aimed $O(1%)$ theore

D. Melikhov, N. Nikitin, S. Simula

We discuss a possibility to probe right-handed weak hadronic currents in rare semileptonic b -> s transitions. It is shown that within models involving right-handed as well as left-handed quark currents (LR models) one can expect a strong enhancement of the right-handed K* production in B -> K* l+ l- decays compared with models including only left-handed qua

J. J. Yang, H. Q. Shen, G. L. Li, T. Huang

The leading nonperturbative QCD corrections to the one gluon exchange quark-quark, quark-antiquark and $q \bar{q}$ pair-excitation potentials are derived by using a covariant form of nonlocal two-quark and two-gluon vacuum expectation values. Our numerical calculation indicates that the correction of quark and gluon condensates to the quark-antiquark potenti

Yuan-ben Dai, Ming-qiu Huang

Exclusive semileptonic $B$ decays into excited charmed mesons are studied with QCD sum rules in the leading order of heavy quark effective theory. Two universal Isgur-Wise functions τand ζfor semileptonic B decays into four lowest lying excited $D$ mesons ($D_1$, $D_2^*$, $D'_0$, and $D'_1$) are determined. The decay rates and branching ratios for th

P. Bicudo, N. Brambilla, E. Ribeiro, A. Vairo

Assuming a Gaussian approximation for the QCD gluodynamics, all the nonperturbative physics can be encoded into two parameters: the gluon correlation length $T_g$ and the gluon condensate $G_2$. These parameters are sufficient in order to describe the heavy-heavy quark nonperturbative interaction. In this work we adopt the same framework in order to study he

R. N. Faustov, A. P. Martynenko

In the framework of the quasipotential method we calculate the contributions of the kind (Zα)^6m_e^2/m_μto the energy spectrum of the muonium n^3S_1 states. Numerical value of obtained correction for 2^3S_1-1^3S_1 muonium fine structure interval is equal to 0.19 MHz.

Antonio Vairo

We derive the so-called Barbieri-Remiddi solution of the Bethe-Salpeter equation in QED in its general form and discuss its application to the bound state energy spectrum.

D. W. Murray, V. V. Flambaum

We consider a mechanism by which dyons (electrically charged magnetic monopoles) can produce both a T- and P-odd (i.e. time reversal invariance and parity violating) mixed polarizability beta [defined by Delta E = -beta E.B, where Delta E is the energy change when electric (E) and magnetic (B) fields are applied to a system] and a T- and P-odd interaction be

J. Kalinowski

Formation of the $s$-channel slepton resonances at LEP2 or Tevatron at current energies is an exciting possibility in R-parity violating SUSY models. Existing LEP2 and Tevatron data can be exploited to look for sleptons, or to derive bounds on the Yukawa couplings of sleptons to quark and lepton pairs.

Adrian Dumitru, Nils Hammon

We discuss the transverse momentum distribution of thermal and prompt photons in ultrarelativistic heavy ion collisions. The prompt photons are mostly produced by fragmentation of quark jets (bremsstrahlung). If these quark jets suffer a large energy loss in heavy-ion reactions, prompt photons are significantly suppressed. Thermal electromagnetic radiation f

James W. York,

Studies of new hyperbolic systems for the Einstein evolution equations show that the ``slicing density'' $α(t,x)$ can be freely specified while the lapse $N = αg^{1/2}$ cannot. Implementation of this small change in the Arnowitt-Deser-Misner action principle leads to canonical equations that agree with the Einstein equations whether or not the constr

S. M. Cronenwett, S. M. Maurer, S. R. Patel, C. M. Marcus

Signatures of &#34;mesoscopic Coulomb blockade&#34; are reported for quantum dots with one fully transmitting point-contact lead, T1 = 1, T2 << 1. Unlike Coulomb blockade (CB) in weak-tunneling devices (T1, T2 << 1), one-channel CB is a mesoscopic effect requiring quantum coherence. Several distinctive features of mesoscopic CB are observed, including a redu

Rajeev Ahluwalia

We perform computer simulations of a Cahn-Hilliard model of phase separation which has dynamical asymmetry between the two coexisting phases. The dynamical asymmetry is incorporated by considering a mobility function which is order parameter dependent. Simulations of this model reveal morphological features similar to those observed in viscoelastic phase sep

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

Recent experiments indicate that the spin-density waves (SDWs) in (TMTTF)_2Br, (TMTSF)_2PF_6 and alpha-(BEDT-TTF)_2MHg(SCN)_4 are highly unconventional and coexist with charge-density waves (CDWs). We present a microscopic theory of this unusual CDW-SDW coexistence. A complete understanding requires the explicit inclusion of strong Coulomb interactions, latt

S. N. Dorogovtsev

Evolution of mixing of granular solids in a slowly rotated 2D drum is considered as a discrete mapping. The rotation is around the axis of the upright drum which is filled partially, and the mixing occurs only at a free surface of a material. The most simple cases that demonstrate clearly the essence of such a type of mixing are studied analytically. We calc

Yoseph Imry

We start by reviewing some interesting results in mesoscopic physics illustrating nontrivial insights on Quantum Mechanics. We then review the general principles of dephasing (sometimes called &#34;decoherence&#34;) of Quantum-Mechanical interference by coupling to the environment degrees of freedom. A particular recent example of dephasing by a current-carr

D. Sornette

In the standard rebound theory of earthquakes, elastic deformation energy is progressively stored in the crust until a threshold is reached at which it is suddenly released in an earthquake. We review three important paradoxes, the strain paradox, the stress paradox and the heat flow paradox, that are difficult to account for in this picture, either individu

P. W. Brouwer, I. L. Aleiner

We study the effect of electron-electron interaction on the conductance of open quantum dots. We find that Coulomb interactions (i) do not affect the ensemble averaged conductance <G> if time-reversal symmetry has been broken by a magnetic field, (ii) enhance weak localization and weak anti-localization corrections to <G> in the absence of a magnetic field,

Avraham Schiller, Frithjof B. Anders, Daniel L. Cox

We investigate the mixed-valent regime of a two-configuration Anderson impurity model for uranium ions, with separate quadrupolar and magnetic doublets. With a new Monte Carlo approach and the non-crossing approximation we find: (i) A non-Fermi-liquid fixed point with two-channel Kondo model critical behavior; (ii) Distinct energy scales for screening the lo

Thereza Paiva, Raimundo R. dos Santos

We study the Metal-Insulator transition in one-dimensional Hubbard superlattices (SL&#39;s), modelled by a repeated pattern of repulsive (i.e., positive on-site coupling) and free sites. The evolution of the local moment and of the charge gap (calculated from Lanczos diagonalization of chains up to 18 sites), together with a strong coupling analysis, show th

J. Gaite, J. Margalef-Roig, S. Miret-Artés

In this work we classify the singularities obtained from the Gibbs potential of a lattice gas model with three components, two order parameters and five control parameters applying the general theorems provided by Catastrophe Theory. In particular, we clearly establish the existence of Landau potentials in two variables or, in other words, corank 2 canonical

Fausto Borgonovi, Paolo Conti, Daniela Rebuzzi, Bambi Hu

Classical and quantum properties of the Bunimovich stadium in the diffusive regime are reviewed. In particular, the quantum properties are directly investigated using an approximate quantum map. Different localized regimes are found, namely, perturbative, quasi-integrable (due to classical Cantori), dynamical and ergodic.

H. H. Strey, V. A. Parsegian, R. Podgornik

The first part of this paper develops a theory for the free energy of lyotropic polymer nematic liquid crystals. We use a continuum model with macroscopic elastic moduli for a polymer nematic phase. By evaluating the partition function, considering only harmonic fluctuations, we derive an expression for the free energy of the system. We find that the configu

G. Iannaccone, C. Ungarelli, M. Macucci, E. Amirante

Information in a Quantum Cellular Automata architecture is encoded in the polarizazion state of a cell, i.e., in the occupation numbers of the quantum dots of which the cell is made up. Non-invasive charge detectors of single electrons in a quantum dot are therefore needed, and recent experiments have shown that a quantum constriction electrostatically coupl

B. I. Belevtsev, N. V. Dalakova, A. S. Panfilov

The unusual non-linear effects in hopping conduction of single-crystal La_{2}CuO_{4 + δ} with excess oxygen has been observed. The resistance is measured as a function of applied voltage U (10^{-3} V - 25 V) in the temperature range 5 K < T < 300 K. At relatively high voltage (U > 0.1 V) the conduction of sample investigated corresponds well to Mott&#39;s va

J. Zi, J. Wan, C. Zhang

We show that it is possible to enlarge the range of low transmission in 1D photonic crystals by using photonic quantum well structures. If a defect is introduced in the photonic quantum well structures, defect modes with a very high quality factor may appear. The transmission of the defect mode is due to the coupling between the eigenmodes of the defect and

J. Loos, H. Fehske

An effective one-band Hamiltonian for colossal-magnetoresistance (CMR) manganites is constructed and the spin excitations are determined. Fitting the experimental data by the derived spin-wave dispersion gives an e_g -electron hopping amplitude of about 0.2 eV in agreement with LDA band calculations.

J. Zi, K. Zhang, x. Xie

Raman scattering from the acoustic phonons confied in si nanocrystals is investigated by a microscopic lattice-dynamical calculation. Polarized and depolarized spectra are found to be rather different, indicated from different acoustic phonons. The polarized scattering is more pronounced than the depolarized one. The calculated results are compared with the

Baigeng Wang, Jian Wang, Hong Guo

We present a solution to the problem of AC current partition in a multi-probe mesoscopic conductor within the nonequilibrium Green&#39;s function formalism. This allows the derivation of dynamic conductance which is appropriate for nonequilibrium situations and which satisfies the current conservation and gauge invariance requirements. This formalism present

Adwait Ratnaparkhi

We present several unsupervised statistical models for the prepositional phrase attachment task that approach the accuracy of the best supervised methods for this task. Our unsupervised approach uses a heuristic based on attachment proximity and trains from raw text that is annotated with only part-of-speech tags and morphological base forms, as opposed to a

N. Abarenkova, J-. Ch. Anglès d&#39;Auriac, S. Boukraa, J. -M. Maillard

We first study birational mappings generated by the composition of the matrix inversion and of a permutation of the entries of $ 3 \times 3 $ matrices. We introduce a semi-numerical analysis which enables to compute the Arnold complexities for all the $9!$ possible birational transformations. These complexities correspond to a spectrum of eighteen algebraic

M. K. Stephen Yeung, Steven H. Strogatz

We generalize the Kuramoto model of coupled oscillators to allow time-delayed interactions. New phenomena include bistability between synchronized and incoherent states, and unsteady solutions with time-dependent order parameters. We derive exact formulas for the stability boundaries of the incoherent and synchronized states, as a function of the delay, in t

Mario Mateo, Denise Hurley-Keller, James Nemec

We have discovered 20 dwarf Cepheids (DC) in the Carina dSph galaxy from the analysis of individual CCD images obtained for a deep photometric study of the system. These short-period pulsating variable stars are by far the most distant (~100 kpc) and faintest (V ~ 23.0) DCs known. The Carina DCs obey a well-defined period-luminosity relation, allowing us to

Taft E. Armandroff, James E. Davies, George H. Jacoby

We present images and a color-magnitude diagram for And V, a new dwarf spheroidal companion to M31 that was found using a digital filtering technique applied to 1550 square degrees of the second Palomar Sky Survey. And V resolves into stars easily in follow-up 4-m V- and I-band images, from which we deduce a distance of 810 +/- 45 kpc using the tip of the re

Markus Kissler-Patig, Karl Gebhardt

We revisit the kinematical data for 204 globular clusters in the halo of M87. Beyond 3 r_eff along the major axis of the galaxy light, these globular clusters exhibit substantial rotation (~ 300 +/- 70 km/s) that translates into an equally substantial spin (lambda ~ 0.18). The present appearance of M87 is most likely the product of a single major merger, sin

Michael L. Sitko, Carol A. Grady, David K. Lynch, Ray W. Russell

The debris disks surrounding the pre-main sequence stars HD 31648 and HD 163296 were observed spectroscopically between 3 and 14 microns. Both possess a silicate emission feature at 10 microns which resembles that of the star beta Pictoris and those observed in solar system comets. The structure of the band is consistent with a mixture of olivine and pyroxen

Dongsu Ryu, Francesco Miniati, T. W. Jones, Adam Frank

A description is given for preserving ${\bmsy\nabla}\cdot{\vec B}=0$ in a magnetohydrodynamic (MHD) code that employs the upwind, Total Variation Diminishing (TVD) scheme and the Strang-type operator splitting for multi-dimensionality. The method is based on the staggered mesh technique to constrain the transport of magnetic field: the magnetic field compone

A. Rozanska

We study the vertical structure of the transition layer between an accretion disc and corona in the context of the existence of two-phase medium in thermally unstable regions. The disc is illuminated by hard X-ray radiation and satisfies the condition of hydrostatic equilibrium. We take into account the energy exchange between hot corona ($\sim 10^8$ K) and

C. Motch

We report the discovery of a transient jet in the supersoft X-ray source RX J0925-4758 . The jet was observed in the Halpha line during a single night in June 1997 and had disappeared one day later. RX J0925-4758 is the third supersoft source to exhibit collimated outflows. The peak jet velocity of 5,200 km/s, strongly argues in favour of a white dwarf in RX

Kazuhiro Yamamoto, Naoshi Sugiyama

Equations to investigate fluctuations in cosmic X-ray background radiation due to point-like sources at high-redshift are formulated in a systematic way. The angular power spectrum of X-ray background fluctuations is investigated from large-scales to small-scales in various cosmological models such as open universe models and models with the cosmological con

W. Kluzniak

If the ordinary neutrinos oscillate into a sterile flavor in a manner consistent with the Super-Kamiokande data on the zenith-angle dependence of atmospheric mu-neutrino flux, an energy sufficient to power a typical cosmic gamma-ray burst (GRB) (about 10^{52} erg) can be carried by sterile neutrinos away from the source and deposited in a region relatively f

Francine R. Marleau, Luc Simard

We measure quantitative structural parameters of galaxies in the Hubble Deep Field (HDF) on the drizzled F814W images. Our structural parameters are based on a two-component surface brightness made up of a Sérsic profile and an exponential profile. We compare our results to the visual classification of van den Bergh et al. (1996) and the $C-A$ classification

Steven S. Gubser

In light of the AdS/CFT correspondence, it is natural to try to define a conformal field theory in a large N, strong coupling limit via a supergravity compactification on the product of an Einstein manifold and anti-de Sitter space. We consider the five-dimensional manifolds T^{pq} which are coset spaces (SU(2) x SU(2))/U(1). The central charge and a part of

S. C. Odewahn, S. G. Djorgovski, S. R. Kulkarni, M. Dickinson

We report on Hubble Space Telescope (HST) observations of the host galaxy of GRB 971214, about four months after the burst. The redshift of the proposed host galaxy at z=3.418, combined with optical and radio observations of the burst afterglow, implies the extremely large isotropic energy release from the burst in gamma-rays of approximately 3x10^53 ergs, s

G. E. Brown, C. -H. Lee, H. A. Bethe

In this note we suggest that high-mass black holes; i.e., black holes of several solar masses, can be formed in binaries with low-mass main-sequence companions, provided that the hydrogen envelope of the massive star is removed in common envelope evolution which begins only after the massive star has finished He core burning. That is, the massive star is in

I. S. Sogami, H. Tanaka, T. Shinohara

Single and double universal seesaw mechanisms and the hypothesis of universal strength for Yukawa couplings are applied to formulate a unified theory of fermion mass spectrum in a model based on an extended Pati-Salam symmetry. Five kinds of Higgs fields are postulated to mediate scalar interactions among electroweak doublets of light fermions and electrowea

Shmuel Elitzur, Eliezer Rabinovici, Gor Sarkissian

We discuss the effect of relevant boundary terms on the nature of branes. This is done for toroidal and orbifold compactifications of the bosonic string. Using the relative minimalization of the boundary entropy as a guiding principle, we uncover the more stable boundary conditions at different regions of moduli space. In some cases, Neumann boundary conditi

G. Feverati, F. Ravanini, G. Takacs

A non-linear integral equation (NLIE) governing the finite size effects of excited states of even topological charge in the sine-Gordon (sG) / massive Thirring (mTh) field theory, deducible from a light-cone lattice formulation of the model, has been known for some time. In this letter we conjecture an extension of this NLIE to states with odd topological ch

Piotr T. Chrusciel

In a recent paper Królak and Beem have shown differentiability of Cauchy horizons at all points of multiplicity one. In this note we give a simpler proof of this result.

A. Abada, O. Azi

We calculate $γ_l(0)$, the damping rate for longitudinal on-shell gluons with zero momentum in hot QCD using the hard-thermal-loop (htl) scheme. We find it to be divergent in the infrared, which means that in this scheme $γ_l(0)$ is different from $γ_t(0)$, the corresponding damping rate for transverse gluons which is known to be finite. This result suggests

S. Alexandrov

The local symmetry transformations of the quantum effective action for general gauge theory are found. Additional symmetries arise under consideration of background gauges. Together with &#34;trivial&#34; gauge transformations, vanishing on mass shell, they can be used for construction simple gauge generators. For example, for the Yang-Mills theory the class

F. Karsch, M. Oevers, P. Petreczky

We study the Landau gauge propagators of the lattice SU(2) 3d adjoint Higgs model, considered as an effective theory of high temperature 4d SU(2) gauge theory. From the long distance behaviour of the propagators we extract the screening masses. The propagators are studied both in the symmetric and the broken phases of the 3d Higgs model. It is shown that the

M. Beneke

A certain pattern of divergence of perturbative expansions in quantum field theories, related to their small and large momentum behaviour, is known as renormalons. We review formal and phenomenological aspects of renormalon divergence. We first summarize what is known about ultraviolet and infrared renormalons from an analysis of Feynman diagrams. Because in

W. Grimus, P. Stockinger, S. Mohanty

We study the conditions for the existence of neutrino oscillations in the field-theoretical approach which combines neutrino production and detection processes in a single Feynman graph. The ``oscillating neutrino&#39;&#39; is represented by an inner line of this graph where, due to the macroscopic distance L between source and detector, the neutrino propaga

Hideo Suganuma, Hiroko Ichie, Kazuhisa Amemiya, Atsunori Tanaka

We study the confinement physics in QCD in the maximally abelian (MA) gauge using the SU(2) lattice QCD, based on the dual-superconductor picture. In the MA gauge, off-diagonal gluon components are forced to be small, and the off-diagonal angle variable $χ_μ(s)$ tends to be random. Within the random-variable approximation for $χ_μ(s)$, we analytically prove

M. Guainazzi, F. Nicastro, F. Fiore, G. Matt

BeppoSAX observed the low-luminous Seyfert 1 Galaxy NGC4051 in a ultra-dim X-ray state. The 2-10 keV flux (1.26 x 10^{-12} erg/cm^2/s) was about 20 times fainter than its historical average value, and remained steady along the whole observation (~2.3 days). The observed flat spectrum (Γ~ 0.8) and intense iron line (EW ~600 eV) are best explained assuming tha

E. E. Donets, M. N. Tentyukov, M. M. Tsulaia

The application of N=2 supersymmetric quantum mechanics for the quantization of homogeneous systems coupled with gravity is discussed. Starting with the superfield formulation of an N=2 SUSY sigma model, Hermitian self-adjoint expressions for quantum Hamiltonians and Lagrangians for any signature of a sigma-model metric are obtained. This approach is then ap

A. V. Kotikov

We present compact, fully analytical expressions for singular parts of a class of three-loop diagrams which cannot be factorized into lower-loop integrals. As a result of the calculations we obtain the analytical expression for the three-loop effective potential of the massive O(N) ϕ^4 model presented recently by J.-M.Chung and B.K.Chung, Phys.Rev. D56, 6508

C. J. Burden

We revisit our recently proposed formalism for dealing with the heavy quark limit of the quark Dyson-Schwinger equation. An ambiguity inherent in the original version of method is identified and resolved. Our reanalysis illustrates the importance of correctly accounting for the effect of hard gluon momenta on the heavy quark self energy in the vicinity of th

Jyh-Liong Lim, Hsiang-nan Li

We propose a new unified evolution equation for parton distribution functions appropriate for both large and small Bjorken variables $x$, which is an improved version of the Ciafaloni-Catani-Fiorani-Marchesini equation. In this new equation the cancellation of soft divergences between virtual and real gluon emissions is explicit without introducing infrared

Chanyong Park, Sang-Jin Sin

We show that the D-instanton in the $AdS_5 \times S^5$ background is a wormhole connecting the background $AdS_5 \times S^5$ to the flat space $\bf R^{10}$ located at the position of the D-instanton. By a $SL(2,{\bf R})$ rotation of type IIB theory, we can make the {\it global} geometry flat in string frame. We also find that, due to the tight relation betwe

Charanjit S. Aulakh, Michiyasu Nagasawa, Vikram Soni

We examine the compatibility between the one scale model with friction for the evolution of cosmic string networks with the Kibble mechanism for string network formation during a second order phase transition. We find a regime which connects (in a dramatically short time $\sim .1 t_c$) the dense string network (small network scale $L\sim 1/T_c$) created by t

J. Oppenheim, B. Reznik, W. G. Unruh

The role of time in quantum mechanics is discussed. The differences between ordinary observables and an observable which corresponds to the time of an event is examined. In particular, the time-of-arrival of a particle to a fixed location is not an ordinary quantum mechanical observable. While we can measure if the particle arrives, we argue that the time at

Shinsuke M. Nishigaki

We consider unitary invariant random matrix ensembles which obey spectral statistics different from the Wigner-Dyson, including unitary ensembles with slowly (~(log x)^2) growing potentials and the finite-temperature fermi gas model. If the deformation parameters in these matrix ensembles are small, the asymptotically translational-invariant region in the sp

Fabian H. Gaioli, Edgardo T. Garcia Alvarez, Javier Guevara

We study the behavior of a subsystem (harmonic oscillator) in contact with a thermal reservoir (finite set of uncoupled harmonic oscillators). We exactly solve the eigenvalue problem and obtain the temporal evolution of the dynamical variables of interest. We show how the subsystem goes to equilibrium and give quantitative estimates of the Poincaré recurrenc

Fabian H. Gaioli, Edgardo T. Garcia Alvarez

We consider a particular (exactly soluble) model of the one discussed in a previous work. We show numerical results for the time evolution of the main dynamical quantities and compare them with analytical results.