March 1999 arXiv papers — page 23

C. E. Tateyama, K. A. Kingham, P. Kaufmann, B. G. Piner

We present 27 geodetic VLBI maps of OJ 287 obtained from the archive of the Washington correlator. The observations presented here were made between 1990 October and 1996 December. During this period a sequence of six superluminal components has been identified. We measured the proper motion of these components to be approximately 0.5 mas/yr, which is about

F. Masset, M. Tagger

We propose a new dynamical mechanism to account for the bar off-centering observed in many barred galaxies. It is based on the presence of a m=1 density wave, non-linearly excited by the strong m=2 component due to the linearly unstable bar and by a m=3 mode. N-body simulations suggest that this mechanism is at work in the centers of galaxies, and provide a

D. Watson, L. Hanlon, B. McBreen, N. Smith

Radio and optical observations of the possible microlensed BL Lac source MS 0205.7+3509 were obtained simultaneously with ASCA x-ray measurements in February 1997. A single power law model, with a photon index of 2.61, is an adequate fit to the ASCA data, once hydrogenic absorption in excess of the Galactic value is permitted, confirming a previous ROSAT mea

M. Lemoine, J. Audouze, L. Ben Jaffel, P. Feldman

We discuss the measurements of deuterium abundances in high redshift quasar absorbers, in the solar system and in the interstellar medium. We present new results that indicate spatial variations of the deuterium abundance in the interstellar medium at the level of 50% over scales possibly as small as 10 pc, and discuss plausible causes for the origin of thes

E. B. Fomalont, W. M. Goss, A. J. Beasley, S. Chatterjee

We present Very Long Baseline Array phase-referenced measurements of the parallax and proper motion of two pulsars, B0919+06 and B1857-26. Sub-milliarcsecond positional accuracy was obtained by simultaneously observing a weak calibrator source within the 40' field of view of the VLBA at 1.5 GHz. We discuss the merits of using weak close calibrator source

Hans-Walter Rix, Marcella Carollo, Ken Freeman

We present the rotation velocities V and velocity dispersions sigma along the principal axes of seven elliptical galaxies less luminous than M_B= -19.5. These kinematics extend beyond the half-light radii for all systems in this photometrically selected sample. At large radii the kinematics not only confirm that rotation and "diskiness" are important

Tanmay Vachaspati

It has been shown that sub-Planckian models of inflation require initial homogeneity on super-Hubble scales under certain commonly held assumptions. Here I remark on the possible implications of this result for inflationary cosmology.

Boudewijn F. Roukema, Stanislaw Bajtlik

The study of the kinematics of galaxies within clusters or groups has the limitation that only one of the three velocity components and only two of the three spatial components of a galaxy position in six-dimensional phase space can normally be measured. However, if multiple topological images of a cluster exist, then the radial positions and sky plane mean

Eduardo Telles, Steve Maddox

We have carried out an investigation of the environments of low redshift HII galaxies by cross-correlating their positions on the sky with those of faint field galaxies in the Automatic Plate Measuring Machine catalogues. We address the question of whether violent star formation in HII galaxies is induced by low mass companions by statistically estimating th

S. A. Balbus, J. C. B. Papaloizou

The dynamical foundations of $α$ disk models are described. At the heart of the viscous formalism of accretion disk models are correlations in the fluctuating components of the disk velocity, magnetic field, and gravitational potential. We relate these correlations to the large scale mean flow dynamics used in phenomenological viscous disk models. MHD turbul

Steen Hannestad

We investigate the possible effects that deviations from kinetic equilibrium can have on massive particles as they decouple from chemical equilibrium. Different methods of solving the Boltzmann equation yield significantly different relic number densities of such particles. General considerations concerning the Dirac or Majorana structure of the particles ar

H. Mutschke, A. C. Andersen, D. Clement, Th. Henning

We present basic laboratory infrared data on a large number of SiC particulate samples, which should be of great value for the interpretation of the 11.3 micron feature observed in the spectra of carbon-rich stars. The laboratory spectra show a wide variety of the SiC phonon features in the 10-13 micron wavelength range, both in peak wavelength and band shap

D. Carter, T. J. Bridges, G. K. T. Hau

We present kinematic parameters and absorption line strengths for three brightest cluster galaxies, NGC 6166, NGC 6173 and NGC 6086. We find that NGC 6166 has a velocity dispersion profile which rises beyond 20 arcsec from the nucleus, with a halo velocity dispersion in excess of 400 km/s. All three galaxies show a positive and constant h4 Hermite moment. Th

Keiichi Kodaira, Vladas Vansevicius, Motohide Tamura, Satoshi Miyazaki

A study of the stellar population of the M31 spiral arm around OB association A24 was carried out based on the photometric data obtained from deep V and JHK imaging. The luminosity function was obtained for -7 <~ Mbol <~ -3.5 by applying the extinction correction corresponding to Av=1 and the bolometric correction BC(K) as an empirical function of (J-K)o. In

Joseph D. Lykken

Recent developments in string theory have important implications for cosmology. Topics discussed here are inflation, the cosmological constant, smoothing of cosmological singularities, and dark matter from parallel universes. Talk presented at the International Workshop on Particle Physics and the Early Universe (COSMO-98), 15-20 Nov, Asilomar, Monterey, CA.

Brad M. S. Hansen

We present new white dwarf cooling models which incorporate an accurate outer boundary condition based on new opacity and detailed radiative transfer calculations. We find that helium atmosphere dwarfs cool considerably faster than has previously been claimed, while old hydrogen atmosphere dwarfs will deviate significantly from black body appearance. We use

M. Kürster, A. P. Hatzes, W. D. Cochran, S. Döbereiner

We present differential radial velocity measurements of Proxima Centauri collected over 4 years with the ESO CES with a mean precision of $54 ms^{-1}$. We find no evidence of a periodic signal that could corroborate the existence of a sub-stellar companion. We put upper limits (97% confidence) to the companion mass ranging from 1.1 to 22 M_{Jup} at orbital p

Robert G. Mann, The UK Submillimetre Survey Consortium

The SCUBA submillimetre camera has opened up new possibilities for tracing the evolution of active star formation in dusty galaxies to high redshift, with profound implications for our understanding of the star formation history of the Universe and the contribution from galaxies to the anisotropy of the microwave sky. We review results from several submillim

Kevin Krisciunas

I give a brief history of astronomical observatories as an institution. This includes: 1) observatories in Islam; 2) China and India; 3) early European observatories; 4) the rise of national observatories; 5) private (amateur) observatories; 6) mountaintop observatories and the modern era. Additional references, to material not cited in the version that will

Tom Banks, Ann Nelson, Michael Dine

Recently, a number of authors have challenged the conventional assumption that the string scale, Planck mass, and unification scale are roughly comparable. It has been suggested that the string scale could be as low as a TeV. In this note, we explore constraints on these scenarios. We argue that the most plausible cases have a fundamental scale of at least 1

S. M. H. Wong

In inclusive P-wave charmonium decay, to cancel infrared divergence in the colour singlet contribution requires the inclusion of the colour octet which becomes degenerate with the former in the infrared limit. In the corresponding exclusive decay, such an infrared divergence does not exist. On this ground, it becomes doubtful whether the colour octet is need

Jonathan A. Tedds, Peter W. J. L. Brand, Michael G. Burton

Observations of H2 velocity profiles in the two most clearly defined Orion bullets are extremely difficult to reconcile with existing steady-state shock models. We have observed [FeII] 1.644um velocity profiles of selected bullets and H2 1-0 S(1) 2.122um velocity profiles for a series of positions along and across the corresponding bow-shaped shock fronts dr

Michael Gutperle

In this note a simple calculation of one loop threshold corrections for the SO(32) heterotic string is performed. In particular the compactification on T^2 with a Wilson line breaking the gauge group to SO(16) x SO(16) is considered. Using heterotic type I duality, these corrections can be related to quantities appearing in the quantum mechanics of type I&#3

J. Borissova, L. Georgiev, M. Rosado, R. Kurtev

We present near infrared JHK photometry for the central area of the irregular dwarf galaxy IC10. Comparing the red supergiants of IC10 and IC1613 we have determined the reddening of E(B-V)=1.05+-0.10 and the dereddened distance modulus (m-M)_0=23.86+-0.12 mag of Population I stars in IC10. Detection of six Brgamma emission structures clearly outline two star

Z. Guralnik

We study discrete fluxes in four dimensional SU(N) gauge theories with a mass gap by using brane compactifications which give ${\cal{N}} = 1$ or ${\cal{N}} = 0$ supersymmetry. We show that when such theories are compactified further on a torus, the t&#39;Hooft magnetic flux $m$ is related to the NS two-form modulus $B$ by $B = 2π{m\over N}$. These values of

A. Djouadi, J. -L. Kneur, G. Moultaka

We analyze the production of neutral Higgs particles in association with the supersymmetric scalar partners of the third generation quarks at future high--energy hadron colliders [upgraded Tevatron, LHC] and $e^+e^-$ linear machines [including the $γγ$ option]. In the Minimal Supersymmetric extension of the Standard Model, the cross section for the associate

Michael Joachim, Thomas Schick

The Gromov-Lawson-Rosenberg-conjecture for a group G states that a closed spin manifold M^n (n>4) with fundamental group G admits a metric with positive scalar curvature if and only if its C^*-index A(M) in KO_n(C^*_r(G)) vanishes. We prove this for groups G with low-dimensional classifying space, provided the assembly map for G is injective. On the other ha

E. Marco, S. Hirenzaki, E. Oset, H. Toki

We study the rho^0 and phi decays into pi^+ pi^- gamma, pi^0 pi^0 gamma and phi into pi^0 eta gamma using a chiral unitary approach to deal with the final state interaction of the M M system. The final state interaction modifies only moderately the large momenta tail of the photon spectrum of the rho^0 --> pi^+ pi^- gamma decay. In the case of phi decay the

M. Dominik

The transition of the binary gravitational lens from the equal mass case to small (planetary) mass ratios q is studied. It is shown how the limit of a (pure shear) Chang-Refsdal lens is approached, under what conditions the Chang-Refsdal approximation is valid, and how the 3 different topologies of the critical curves and caustics for a binary lens are mappe

T. Reisz, H. J. Rothe

We give a perturbative proof that U(1) lattice gauge theories generate the axial anomaly in the continuum limit under very general conditions on the lattice Dirac operator. These conditions are locality, gauge covariance and the absense of species doubling. They hold for Wilson fermions as well as for realizations of the Dirac operator that satisfy the Ginsp

S. Hashimoto, K-I. Ishikawa, H. Matsufuru, T. Onogi

We present a lattice calculation of the B meson B-parameter B_B using the NRQCD action. The heavy quark mass dependence is explicitly studied over a mass range between m_b and 4m_b with the $O(1/m_Q)$ and $O(1/m_Q^2)$ actions. We find that the ratios of lattice matrix elements $<O_N^{lat}>/<A_0^{lat}>^2$ and $<O_S^{lat}>/<A_0^{lat}>^2$, which contribute to B

A. Dobado, M. J. Herrero, S. Penaranda

In the framework of the Minimal Supersymmetric Standard Model we compute the one-loop effective action for the electroweak bosons obtained after integrating out the different sleptons, squarks, neutralinos and charginos, and present the result in terms of the physical sparticle masses. In addition we study the asymptotic behaviour of the two, three and four

T. Kitajima, T. Takayanagi, T. Takemura, I. Terasaki

Anisotropic resistivities of Bi_2Sr_2Ca_{1-x}Er_xCu_2O_8 single crystals were measured and analyzed from 4.2 to 500 K with special interest in the parent antiferromagnetic insulator of x=1.0. Although the resistivity is semiconducting along both the in- and out-of-plane directions, the temperature dependence is found to be significantly different. As a resul

Kazuo Hida

It is conjectured that the Haldane phase of the S=1 antiferromagnetic Heisenberg chain and the $S=1/2$ ferromagnetic-antiferromagnetic alternating Heisenberg chain is stable against any strength of randomness, because of imposed breakdown of translational symmetry. This conjecture is confirmed by the density matrix renormalization group calculation of the st

Venkatesh Gopal, S. Anantha Ramakrishna, A. K. Sood, N. Kumar

We examine using Monte Carlo simulations, photon transport in optically `thin&#39; slabs whose thickness L is only a few times the transport mean free path $l^{*}$, with particles of different scattering anisotropies. The confined geometry causes an auto-selection of only photons with looping paths to remain within the slab. The results of the Monte Carlo si

Kunihito Ioka, Takahiro Tanaka, Takashi Nakamura

Under the assumption that the Milky Way&#39;s dark halo consists of primordial black hole MACHOs (PBHMACHOs), the mass density of the halo can be measured by the low frequency gravitational waves ($10^{-3} Hz \siml ν_{gw} \siml 10^{-1}$ Hz) from PBHMACHO binaries whose fraction is $\sim 10^{-6}$. We find that ten years observation by LISA will detect $\sim 7

K. Hamaguchi, K. -I. Izawa, Yasunori Nomura, T. Yanagida

Superheavy particles of masses $\simeq 10^{13}-10^{14} GeV$ with lifetimes $\simeq 10^{10}-10^{22} years$ are very interesting, since their decays may account for the ultra-high energy (UHE) cosmic rays discovered beyond the Greisen-Zatsepin-Kuzmin cut-off energy $E \sim 5 \times 10^{10} GeV$. We show that the presence of such long-lived superheavy particles

H. E. Boos, V. V. Mangazeev

We obtain the functional relations for the eigenvalues of the transfer matrix of the sl(3) chiral Potts model for q^2=-1. For the homogeneous model in both directions a solution of these functional relations can be written in terms of roots of Bethe ansatz-like equations. In addition, a direct nested Bethe ansatz has also been developed for this case.

Olga Man&#39;ko, V. I. Man&#39;ko

In the probability representation of the standard quantum mechanics, the explicit expression (and its quasiclassical van-Fleck approximation) for the ``classical&#39;&#39; propagator (transition probability distribution), which completely describes the quantum system&#39;s evolution, is found in terms of the quantum propagator. An expression for the ``classi

B. -J. Schaefer, H. -J. Pirner

Nonperturbative flow equations within an effective linear sigma model coupled to constituent quarks for two quark flavors are derived and solved. A heat kernel regularization is employed for a renormalization group improved effective potential. We determine the initial values of the coupling constants in the effective potential at zero temperature. Solving t

M. Post, W. Peters, U. Mosel

In the last years much work has been done to learn about the properties of the $ρ$-meson in nuclear matter. In a calculation of the in-medium spectralfunction of the $ρ$ we find that it is strongly modified by baryonic resonances, especially the $D_{13}(1520)$, through its coupling to resonance-hole states. In order to test the predictions of a model for the

Suk-Ho Hong, Suk-Joon Lee

N-αstructures of light nuclei with axial symmetry are studied using relativistic Hartree approximation. Metastable excited states are searched in a configuration space which allows linear alpha chain structures. As a result, it is shown that ^{12}C has ^8Be + αresonance state at about 1 MeV above ^8Be-αthreshold as an asymmetric 3-αlinear-chain structure, wh

T. Michoel, A. Verbeure

We provide the mathematical structure and a simple, transparent and rigorous derivation of the magnons as elementary quasi-particle excitations at low temperatures and in the infinite spin limit for a large class of Heisenberg ferromagnets. The magnon canonical variables are obtained as fluctuation operators in the infinite spin limit. Their quantum characte

T. Michoel, A. Verbeure

For the phenomenon of Bose-Einstein condensation we construct the canonical pair of field operators of the Goldstone Bosons explicitly as fluctuation operators in the ground state. We consider the imperfect Bose gas as well as the weakly interacting Bose gas. We prove that a canonical pair of fluctuation operators is always related to the order parameter and

Ki Hang Kim, Fred W. Roush

We show the Williams Conjecture is false for irreducible shifts of finite type by examining relative sign-gyration numbers of conjugacies between shifts with no points of period one or two.

Gaoyong Zhang

H. Busemann and C. M. Petty posed the following problem in 1956: If K and L are origin-symmetric convex bodies in R^n and for each hyperplane H through the origin the volumes of their central slices satisfy vol(K cap H) < vol(L cap H), does it follow that the volumes of the bodies themselves satisfy vol(K) < vol(L)? The problem is trivially positive in R^2.

Claire Voisin

We study the higher Abel-Jacobi invariant defined recently by M. Green. We first construct a counterexample to the injectivity of Green&#39;s higher Abel-Jacobi map. On the other hand, we prove that the higher Abel-Jacobi map governs Mumford&#39;s pull-back of holomorphic forms. We deduce from this that if a surface has holomorphic 2-forms, the image of the

Michael Lacey, Christoph Thiele

This paper is a successor of \cite{laceyt}. In that paper we considered bilinear operators of the form H_alpha(f_1,f_2)(x) = p.v. \int f_1(x-t) f_2(x + alpha t)/t dt, which are originally defined for f_1, f_2 in the Schwartz class S(R). The natural question is whether estimates of the form H_alpha(f_1,f_2)|_p <= C_{alpha,p_1,p_2} |f_1|_{p_1} |f_2|_{p_2} with

John H. Palmieri

Let A be the mod 2 Steenrod algebra, and let Q denote the category of exterior sub-Hopf algebras of A, where the morphisms are given by inclusions. The restriction maps Ext_A (Z/2,Z/2) --> Ext_E (Z/2,Z/2), for E in Q, can be assembled into a map i:Ext_A (Z/2, Z/2) --> lim_Q Ext_E (Z/2,Z/2). There is an action of A on this inverse limit, and i factors through

Mikhail Lyubich

We prove the Feigenbaum-Coullet-Tresser conjecture on the hyperbolicity of the renormalization transformation of bounded type. This gives the first computer-free proof of the original Feigenbaum observation of the universal parameter scaling laws. We use the Hyperbolicity Theorem to prove Milnor&#39;s conjectures on self-similarity and &#34;hairiness&#34; of

Richard J. Gardner, Alexander Koldobsky, Thomas Schlumprecht

We derive a formula connecting the derivatives of parallel section functions of an origin-symmetric star body in R^n with the Fourier transform of powers of the radial function of the body. A parallel section function (or (n-1)-dimensional X-ray) gives the ((n-1)-dimensional) volumes of all hyperplane sections of the body orthogonal to a given direction. Thi

Alexander Brudnyi

The main objective of this paper is to prove a new inequality for plurisubharmonic functions estimating their supremum over a ball by their supremum over a measurable subset of the ball. We apply this result to study local properties of polynomial, algebraic and analytic functions. The paper has much in common with an earlier paper of the author.

David Carlton

We study the moduli surface for pairs of elliptic curves together with an isomorphism between their N-torsion groups. The Weil pairing gives a &#34;determinant&#34; map from this moduli surface to (Z/NZ)*; its fibers are the components of the surface. We define spaces of modular forms on these components and Hecke correspondences between them, and study how

Arthur W. Apter

We show relative to strong hypotheses that patterns of compact cardinals in the universe, where a compact cardinal is one which is either strongly compact or supercompact, can be virtually arbitrary. Specifically, we prove if V is a model of ``ZFC + Omega is the least inaccessible limit of measurable limits of supercompact cardinals + f :Omega-->2 is a funct

Michael Kleber

The Jacobi-Trudi formula implies some interesting quadratic identities for characters of representations of $gl_n$. Earlier work of Kirillov and Reshetikhin proposed a generalization of these identities to the other classical Lie algebras, and conjectured that the characters of certain finite-dimensional representations of $U_q(g-affine)$ satisfy it. Here we

B. Siebert, G. Tian

We show that hyperelliptic symplectic Lefschetz fibrations are symplectically birational to two-fold covers of rational ruled surfaces, branched in a symplectically embedded surface. This reduces the classification of genus 2 fibrations to the classification of certain symplectic submanifolds in rational ruled surfaces.

Yair N. Minsky

Thurston&#39;s ending lamination conjecture proposes that a finitely generated Kleinian group is uniquely determined (up to isometry) by the topology of its quotient and a list of invariants that describe the asymptotic geometry of its ends. We present a proof of this conjecture for punctured-torus groups. These are free two-generator Kleinian groups with pa

Selman Akbulut

In his 1974 thesis, Martin Scharlemann constructed a fake homotopy equivalence from a closed smooth manifold f:Q -> S^3 x S^1 # S^2 x S^2 and asked whether the manifold Q itself is diffeomorphic to S^3 x S^1 # S^2 x S^2. Here we answer this question affirmatively.

Yuji Nakawaki, Gary McCartor

We continue McCartor and Robertson&#39;s recent demonstration of the indispensability of ghost fields in the light-cone gauge quantization of gauge fields. It is shown that the ghost fields are indispensable in deriving well-defined antiderivatives and in regularizing the most singular component of gauge field propagator. To this end it is sufficient to conf

Yuji Nakawaki, Gary McCartor

We consider constructing a canonical quantum theory of the light-cone gauge ($A_-$=0) Schwinger model in the light-cone representation. Quantization conditions are obtained by requiring that translational generators $P_+$ and $P_-$ give rise to Heisenberg equations which, in a physical subspace, are consistant with the field equations. A consistent operator

Rolando Gaitan

A gauge formulation for the Proca model quantum theory in an open path functional space representation is revisited. The path dependent vacuum state is obtained. Starting from this one, other excited states can be obtained too. Additionally, the functional integration measure needed to define an internal product in the state space is constructed.

S. James Gates,, Sergei M. Kuzenko

We review the construction of 4D, N =2 globally supersymmetric off-shell nonlinear sigma models whose target spaces are the cotangent bundles of Kähler manifolds.

Sudipta Mukherji

We analyse the dipole solution of heterotic string theory in four dimensions. It has the structure of monopole and anti-monopole connected by flux line (string). Due to growing coupling near the poles, the length of the string diverges. However, exploiting the self-duality of heterotic string theory in four dimension, we argue that this string is correctly d

Nicola Grillo

We describe the construction of quantum gravity, i.e. of a theory of self-interacting massless spin-2 quantum gauge fields, the gravitons, on flat space-time, in the framework of causal perturbation theory.

E. Lima, H. Lu, B. A. Ovrut, C. N. Pope

We obtain new intersecting 5-brane, string and pp-wave solutions in the heterotic string on a torus and on a K3 manifold. In the former case the 5-brane is supported by Yang-Mills instantons, and in the latter case both the 5-brane and the string are supported by the instantons. The instanton moduli are parameterised by the sizes and locations of the instant

Haisong Yang

We present a class of two-charged intersecting brane solutions of the D=11 supergravity, which contain the M2-brane, M5-brane, Kaluza-Klein monopole or Brinkmann wave as their building blocks. These solutions share the common feature that one charge is smeared out or uniform over all spatial directions occupied by the branes or waves, while the other charge

Jorge Ananias Neto, Wilson Oliveira

The energy eigenvalues of the quantum particle constrained in a surface of the sphere of D dimensions embedded in a $R^{D+1}$ space are obtained by using two different procedures: in the first, we derive the Hamiltonian operator by squaring the expression of the momentum, written in cartesian components, which satisfies the Dirac brackets between the canonic

Theodore J. Allen, M. G. Olsson, Sinisa Veseli

We consider the effects of going beyond the approximation of a straight string in mesons by using a flexible flux tube model wherein a Nambu-Goto string bends in response to quark accelerations. The curved string is dynamically identical to the straight string even for ultra-relativistic mesons except for a small additional radial momentum. We numerically so

Jonathan L. Rosner

This article, in memory of Professor Hiroshi Suura, is devoted to the effects of particles in loops, ranging from quantum electrodynamics to precise tests of the electroweak theory and CP violation.

Peter Lichard

We make an attempt to resolve the discrepancy of the observed e+e- mass spectrum in the K+ --> pi+e+e- decay with that predicted by meson dominance. To this end we investigate the properties of the rho0 propagator. We use dispersion relations to evaluate the running mass squared m_rho^2(t) of the rho0 resonance without adjustable parameters. To improve the c

Edward Boos, Lev Dudko, Thorsten Ohl

We present the results of a complete tree level calculation of the processes pp(\bar p) -> Wb\bar b and Wb\bar b + jet that includes the single top signal and all irreducible backgrounds simultaneously. In order to probe the structure of the Wtb coupling with the highest possible accuracy and to look for possible deviations from standard model predictions, w

Aseshkrishna Datta, Monoranjan Guchait, Kyoung Keun Jeong

In minimal supergravity based supersymmetry models the charged sleptons as well as the sneutrinos may be lighter than the squarks. In such light slepton scenario the search for lighter stop squark has been investigated in the dilepton + missing $p_T(\missingpt)$ +jets ($\ge 1$) channel at Tevatron. In this scenario semileptonic decay of lighter stop squark h

J. A. Coarasa, Jaume Guasch, Joan Sola

We compute Gamma(H+ -> t \bar{b}) at one-loop in the MSSM and show how future data at the Tevatron and/or at the LHC could be used to unravel the potential SUSY nature of the charged Higgs.

J. A. Coarasa, Jaume Guasch, Joan Sola

We present the computation of the leading one-loop electroweak radiative corrections to the non-standard top quark decay width Gamma(t->H+ b), using a physically motivated definition of tan(beta). We find that the corrections are large, both in the Minimal Supersymmetric Standard Model (MSSM) and the Two-Higgs-Doublet Model (2HDM). These corrections have an

A. V. Kuznetsov, N. V. Mikheev

We point out some serious mistakes in the investigation of Zhukovskii et al. Both the amplitude and the probability of the process were calculated wrongly, that is, the problem of the neutrino pair production by a virtual photon in an external magnetic field is still unsolved.

Wojciech Krolikowski

An explicit form of charged--lepton mass matrix, predicting $m_τ= 1776.80$ MeV from the experimental values of $m_e$ and $m_μ$ (in good agreement with the experimental figure $m_τ= 1777.05^{+0.29}_{-0.26}$ MeV), is applied to three neutrinos $ν_e, ν_μ, ν_τ$ in order to correlate tentatively their masses and mixing parameters. It is suggested that for neutrin

Milton Dean Slaughter

The weak $N-Δ$ axial-vector transition amplitude $<Δ| A_{π^{+}}^μ|N>$ - important in $N^{*}$ production processes in general and in isobar models describing $ν_μN\to μΔ$ processes in particular - is examined using a broken symmetry algebraic approach to QCD which involves the realization of chiral current algebras. We calculate a value for the form factor $C

Gideon Alexander, Harry J. Lipkin

The use of isospin invariance and Generalized Bose statistics shows that the Bose-Einstein correlation (BEC) of identical bosons seen in the $K^+K^+$ and $π^+ π^+$ systems can be extended to apply to $K^+ K^o$ and $π^+ π^o$ pairs when they are produced from an initial state with isospin zero; e.g. by the fragmentation of gluons or of a strange quark pair acc

Smaragda Lola

We discuss aspects of neutrino masses and lepton-number violation, in the light of the observations of Super-Kamiokande. As a first step, we use the data from various experiments, in order to obtain a phenomenological understanding of neutrino mass textures. We then investigate how the required patterns of neutrino masses and mixings are related to the flavo

R. Aloisio, V. Azcoiti, G. Di Carlo, A. Galante

Lattice formulation of Finite Baryon Density QCD is problematic from computer simulation point of view; it is well known that for light quark masses the reconstructed partition function fails to be positive in a wide region of parameter space. For large bare quark masses, instead, it is possible to obtain more sensible results; problems are still present but

F. Farchioni

We argue that lattice QCD with Ginsparg-Wilson fermions satisfies the Leutwyler-Smilga sum rules for the eigenvalues of the chiral Dirac operator. The result is obtained in the one flavor case, by rephrasing Leutwyler and Smilga&#39;s original analysis for the finite volume partition function. This is a further evidence that Ginsparg-Wilson fermions, even if

Jean-Philippe Uzan

We study the existence and stability of cosmological scaling solutions of a non-minimally coupled scalar field evolving in either an exponential or inverse power law potential. We show that for inverse power law potentials there exist scaling solutions the stability of which does not depend on the coupling constant $ξ$. We then study the more involved case o

Abhas Mitra

We point out that although the pioneering work of Oppenheimer and Snyder (OS), technically, indicated the formation of an event horizon for a collapsing homogeneous dust ball of mass $M_b$ and radius $R_b$, the Eqs. (32) and (36) of their paper actually demand that no trapped surface is formed $ 2GM_b/ R_b c^2 \le 1$, and $M_b \equiv 0$! Anybody may verify i

T. B. Dinesh, M. Haveraaen, J. Heering

The abstract mathematical theory of partial differential equations (PDEs) is formulated in terms of manifolds, scalar fields, tensors, and the like, but these algebraic structures are hardly recognizable in actual PDE solvers. The general aim of the Sophus programming style is to bridge the gap between theory and practice in the domain of PDE solvers. Its ma

R. Milson

These notes are a brief introduction to the RSA algorithm and modular arithmetic. They are intended for an undergraduate audience.

Lev I. Deych, A. Yamilov, A. A. Lisyansky

We consider tunneling of electromagnetic waves through a polariton band gap of a 1-D chain of atoms. We analytically demonstrate that a defect embedded in the structure gives rise to the resonance transmission at the frequency of a local polariton state associated with the defect.

Christopher Mudry, P. W. Brouwer, Akira Furusaki

The random magnetic flux problem on a lattice and in a quasi one-dimensional (wire) geometry is studied both analytically and numerically. The first two moments of the conductance are obtained analytically. Numerical simulations for the average and variance of the conductance agree with the theory. We find that the center of the band $ε=0$ plays a special ro

Igor V. Yurkevich, Igor V. Lerner

We show that for all the three standard symmetry classes (unitary, orthogonal and symplectic), the conventional replica nonlinear sigma model gives the correct non-perturbative result for the two-level correlation functions R_2(ω) of electrons in disordered metals in the limit of large ω. In this limit, non-perturbative oscillatory contributions arise from a

V. M. Krasnov, D. Winkler

We study numerically and analytically the shape of a single fluxon moving in a double stacked Josephson junctions (SJJ&#39;s) for various junction parameters. We show that the fluxon in a double SJJ&#39;s consists of two components, which are characterized by different Swihart velocities and Josephson penetration depths. The weight coefficients of the two co

S. Bellucci, J. Gonzalez

We consider a one-dimensional electron system, suitable for the description of the electronic correlations in a metallic carbon nanotube. Renormalization group methods are used to study the low-energy behavior of the unscreened Coulomb interaction between currents of well-defined chirality. In the limit of a very large number n of subbands we find a strong r

M. C. Diamantini, H. Kleinert, C. A. Trugenberger

Floppy membranes are tensionless surfaces without extrinsic stiffness, whose fluctuations are governed by fourth-order bending elasticity. This suppresses spiky superstructures and ensures that floppy membranes remain smooth over any distance, with Hausdorff dimension D=2, in contrast to surfaces with stiffness, which are rough on the scale of some finite pe

S. Anantha Ramakrishna, N. Kumar

The propagation of light in a scattering medium is described as the motion of a special kind of a Brownian particle on which the fluctuating forces act only perpendicular to its velocity. This enforces strictly and dynamically the constraint of constant speed of the photon in the medium. A Fokker-Planck equation is derived for the probability distribution in

A. Coniglio, M. Nicodemi

In the present paper, we analyze the consequences of scaling hypotheses on dynamic functions, as two times correlations $C(t,t&#39;)$. We show, under general conditions, that $C(t,t&#39;)$ must obey the following scaling behavior $C(t,t&#39;) = ϕ_1(t)^{f(β)}{\cal{S}}(β)$, where the scaling variable is $β=β(ϕ_1(t&#39;)/ϕ_1(t))$ and $ϕ_1(t&#39;)$, $ϕ_1(t)$ two

Anael Lemaitre, Hugues Chate

The phase ordering properties of lattices of band-chaotic maps coupled diffusively with some coupling strength $g$ are studied in order to determine the limit value $g_e$ beyond which multistability disappears and non-trivial collective behavior is observed. The persistence of equivalent discrete spin variables and the characteristic length of the patterns o

Yoseph Imry, Hidetoshi Fukuyama, Peter Schwab

Electronic quantum effects in disordered conductors are controlled by the dephasing rate of conduction electrons. This rate is expected to vanish with the temperature. We consider the very intriguing recently reported apparent saturation of this dephasing rate in several systems at very low temperatures. We show that the ``standard model&#39;&#39; of a condu

K. Stokbro

We report a first principles study of the structure and the vibrational properties of the Si(100)-H(2 \times 1) surface in an electric field. The calculated vibrational parameters are used to model the vibrational modes in the presence of the electric field corresponding to a realistic STM tip-surface geometry. We find that local one-phonon excitations have

A. Eschmann, R. J. Ballagh, B. M. Caradoc-Davies

Numerical simulations of Ramsey fringe formation in double Bose condensates are carried out in two spatial dimensions. The effects of meanfield nonlinearity and diffusion in the condensates give rise to new features in the Ramsey fringes, namely spatial variation and an asymmetry between positive and negative field detunings. We introduce the concept of an e

M. B. Walker

A formally exact expression for the tunneling current, for its separation into specular and diffuse components, and for its directionality, is given for a thick tunnel junction with rough interfaces in terms of the properties of appropriately defined scattering amplitudes. An approximate evaluation yields the relative magnitudes of the specular and diffuse c

Sun Hong Rhie

The recent binary microlensing event toward the Small Magellanic Cloud MACHO-98-SMC-1 was alerted by the MACHO collaboration and monitored by many microlensing experiments for its complete coverage of the second caustic crossing. The purpose of this global monitoring campaign was to determine the relative proper motion $|\vecμ|$ of the lensing object with re

Xiangdong Shi, Geza Gyuk

We suggest that the deceleration of the relativistic shock by a denser part of the interstellar medium off line-of-sight produced the observed radio ``flare&#39;&#39; in the early afterglow of GRB990123. We find that this scenario is consistent with observations if the particle number density of this denser part of the medium is between $\sim 200$ and $\sim