January 1997 arXiv papers — page 3

R. Canal, J. Gutierrez

The current status of the problem of whether neutron stars can form, in close binary systems, by accretion-induced collapse (AIC) of white dwarfs is examined. We find that, in principle, both initially cold C+O white dwarfs in the high-mass tail of their mass distribution in binaries and O+Ne+Mg white dwarfs can produce neutron stars. Which fractions of neut

Rosemary F. G. Wyse, Gerard Gilmore, Marijn Franx

We review current knowledge on the structure, properties and evolution of galactic bulges, considering particularly common preconceptions in the light of recent observational results.

Raul Jimenez

In this article I review the main methods for determining the age of the Universe. I describe how to determine the age of the oldest known systems at z=0, the system of galactic globular clusters, using different techniques. I also describe how to date the Universe using the decay of radioactive elements (Cosmochronology). Finally, I focus on how to determin

Helmut Jerjen, Bruno Binggeli

We review the systematic properties of ``dwarf'' elliptical (dE) galaxies, focussing on the relation between ``normal'' and ``dwarf'' ellipticals. In recent years, this relation has been described as ``dichotomy'' -- based essentially on a discontinuity in central surface brightness. We show that, outside of 300 pc from the ce

Said Azziz

Soit $H_{d,g}$ le schéma de Hilbert des courbes lisses et connexes de degré $d$ et genre $g$ de l'espace projectif ${\bf P}^3$ sur un corps $k$ algébriquement clos de caractéristique nulle. Le but principal de cet article est d'exhiber des composantes irréductibles et non réduites de $H_{d,g}$ dont l'élément général correspond à une courbe tracée

Carlo Gasbarri

Let $K$ be a number field, $\OK$ be its ring of integers. We introduce the notion of compactified representation of $GL_N(\OK)$ and, we see how to associate to a hermitian vector bundle $\E$ over $\Spec(\OK)$ and a compactified representation $\T$, a hermitian tensor bundle $\E_T$. We can prove then that there exists a lower bound for the heights of points $

CCFR Collaboration, W. Seligman

We present an improved determination of the proton structure functions $F_{2}$ and $xF_{3}$ from the CCFR $ν$-Fe deep inelastic scattering (DIS) experiment. Comparisons to high-statistics charged-lepton scattering results for $F_{2}$ from the NMC, E665, SLAC, and BCDMS experiments, after correcting for quark-charge and heavy-target effects, indicate good agr

M. Scheunert, R. B. Zhang

The cohomology groups of Lie superalgebras and, more generally, of color Lie algebras, are introduced and investigated. The main emphasis is on the case where the module of coefficients is non-trivial. Two general propositions are proved, which help to calculate the cohomology groups. Several examples are included to show the peculiarities of the super case.

Ali Mostafazadeh

The necessary and sufficient conditions for the exactness of the semiclassical approximation for the solution of the Schrödinger and Klein-Gordon equations are obtained. It is shown that the existence of an exact semiclassical solution of the Schrödinger equation determines both the semiclassical wave function and the interaction potential uniquely up to the

Robert Friedman, John Morgan, Edward Witten

To understand in detail duality between heterotic string and F theory compactifications, it is important to understand the construction of holomorphic G bundles over elliptic Calabi-Yau manifolds, for various groups G. In this paper, we develop techniques to describe the bundles, and make several detailed comparisons between the heterotic string and F theory

B. Moussallam

A classic sum rule by Das et al. is extended to seven of the low-energy constants $K_i$, introduced by Urech, which parameterize electromagnetic corrections at chiral order $O(e^2p^2)$. Using the spurion formalism, a simple convolution representation is shown to hold and the structure in terms of the chiral renormalization scale, the QCD renormalization scal

A. Bartl, H. Eberl, K. Hidaka, T. Kon

We calculate the supersymmetric QCD corrections in order $α_s$ to the the widths of the Higgs boson decays $H^+ \to \st \bar\sb$ and $H^0, A^0 \to \st \bar\st, \sb \bar\sb$ in the on--shell scheme within the Minimal Supersymmetric Standard Model. We find that the QCD corrections are significant, but that the squark pair decay modes are still dominant in a wi

J. Horejsi, M. Schnabl

We present a simple derivation of the one-loop trace anomaly in spinor QED through dispersion relations, avoiding completely any ultraviolet regularization. The anomaly can be expressed as a convergent sum rule for the imaginary part of a relevant formfactor. In the massless limit, the imaginary part produces a delta-function singularity at zero external mom

Holger Frahm, John Schliemann

We introduce a family of Jastrow pair product states for quasi one-dimensional spin systems. Depending on a parameter they interpolate between the resonating valence bond ground state of the Haldane-Shastry model describing a spin liquid and the (dimerized) valence bond solid ground states of the Majumdar-Ghosh spin chain. These states are found to form an e

Alessandro Cuccoli, Alessandro Macchi, Gaia Pedrolli, Valerio Tognetti

The kinetic energy of solid neon is calculated by a path-integral Monte Carlo approach with a refined Trotter- and finite-size extrapolation. These accurate data present significant quantum effects up to temperature T=20 K. They confirm previous simulations and are consistent with recent experiments.

Alessandro Cuccoli, Andrea Rossi, Valerio Tognetti, Ruggero Vaia

Classical-like formulas are given in order to evaluate thermal averages of observables belonging to a quantum nonlinear system with dissipation described by the Caldeira-Leggett model [Phys. Rev. Lett. 46, 211 (1981); Ann. Phys. (N.Y.) 149, 374 (1983)]. The underlying scheme is the pure-quantum self-consistent harmonic approximation, which leads to expressio

Shinji Mukohyama, Masafumi Seriu, Hideo Kodama

Entanglement entropy is often speculated as a strong candidate for the origin of the black-hole entropy. To judge whether this speculation is true or not, it is effective to investigate the whole structure of thermodynamics obtained from the entanglement entropy, rather than just to examine the apparent structure of the entropy alone or to compare it with th

George Lake, Neal Katz, Ben Moore

We have simulated disk galaxies undergoing continual bombardment by other galaxies in a rich cluster. "Galaxy harassment" leads to dramatic evolution of smaller disk galaxies and provides an extremely effective mechanism to fuel a central quasar. Within a few billion years after a small disk galaxy enters the cluster environment, up to 90% of its gas

Ben Moore, George Lake, Neal Katz

Galaxy morphologies in clusters have undergone a remarkable transition over the past several billion years. Distant clusters at $z \sim 0.4$ are filled with small spiral galaxies, many of which are disturbed and show evidence of multiple bursts of star-formation. This population is absent from nearby clusters where spheroidals comprise the faint end of the l

Tadakatsu Sakai

Duality in supersymmetric SU(N) gauge theory with a symmetric tensor is studied using the technique of deconfining and Seiberg's duality. By construction the gauge group of the dual theory necessarily becomes a product group. In order to check the duality, several nontrivial consistency conditions are examined. In particular we find that by deforming alo

K. L. Vaninsky

We consider various trace formulas for the cubic Schrodinger equation in the space of infinitely smooth functions subject to periodic boundary conditions. The formulas relate conventional integrals of motion to the periods of some Abelian differentials (holomorphic one-forms) on the spectral curve. We show that the periods of Abelian differentials are global

Markus Simonius

The reduction paradigm of quantum interferometry and the objectivation problem in quantum measurements are reanalyzed. Both are shown to be amenable to straightforward mathematical treatment within "every-users" simple-minded quantum mechanics without reduction postulate etc., using only its probabilistic content.

Naihuan Jing, Yoshitaka Koyama

Using our recent bosonic realization of $U_q(\widehat{sp}_{2n})$, we construct explicitly the vertex operators for the level -1/2 modules of $U_q(\widehat{sp}_{2n})$ using bosonic fields. Our method contains a detailed analysis of all the q-intertwining relations.

Naihuan Jing, Yoshitaka Koyama, Kailash C. Misra

We construct explicitly the quantum symplectic affine algebra $U_q(\widehat{sp}_{2n})$ using bosonic fields. The Fock space decomposes into irreducible modules of level -1/2, quantizing the Feingold-Frenkel construction for q=1.

Naihuan Jing, Kailash C. Misra

We construct explicitly the $q$-vertex operators (intertwining operators) for the level one modules $V(Λ_i)$ of the classical quantum affine algebras of twisted types using interacting bosons, where $i=0, 1$ for $A_{2n-1}^{(2)}$, $i=0$ for $D_4^{(3)}$, $i=0, n$ for $D_{n+1}^{(2)}$, and $i=n$ for $A_{2n}^{(2)}$. A perfect crystal graph for $D_4^{(3)}$ is cons

Tanya Khovanova

In the Hopf algebra GL_{p,q}(2) the determinant is central iff p=q. In this case we put determinant to be equal to 1 to get SL_q(2). In this paper I consider the case when p/q is a root of unity; and, consequently, a power of the determinant is central.

H. Awata, S. Odake, J. Shiraishi

We present a q-difference realization of the quantum superalgebra U_q(sl(M|N)), which includes Grassmann even and odd coordinates and their derivatives. Based on this result we obtain a free boson realization of the quantum affine superalgebra U_q(\widehat{sl}(2|1)) of an arbitrary level k.

C. Quesne, N. Vansteenkiste

The representation theory of the generalized deformed oscillator algebras (GDOA's) is developed. GDOA's are generated by the four operators ${1,a,a^†,N}$. Their commutators and Hermiticity properties are those of the boson oscillator algebra, except for $[a, a^†]_q = G(N)$, where $[a,b]_q = a b - q b a$ and $G(N)$ is a Hermitian, analytic function. T

D. Bonatsos, C. Daskaloyannis, P. Kolokotronis, A. Ludu

The most common nonlinear deformations of the su(2) Lie algebra, introduced by Polychronakos and Ro\v cek, involve a single arbitrary function of J_0 and include the quantum algebra su_q(2) as a special case. In the present contribution, less common nonlinear deformations of su(2), introduced by Delbecq and Quesne and involving two deforming functions of J_0

D. Bonatsos, C. Daskaloyannis, P. Kolokotronis, A. Ludu

Nonlinear deformations of the enveloping algebra of su(2), involving two arbitrary functions of J_0 and generalizing the Witten algebra, were introduced some time ago by Delbecq and Quesne. In the present paper, the problem of endowing some of them with a Hopf algebraic structure is addressed by studying in detail a specific example, referred to as ${\cal A}

Radford M. Neal

Gaussian processes are a natural way of defining prior distributions over functions of one or more input variables. In a simple nonparametric regression problem, where such a function gives the mean of a Gaussian distribution for an observed response, a Gaussian process model can easily be implemented using matrix computations that are feasible for datasets

A. T. Yinnon, D. A. Hamburger, I. Farbman, R. B. Gerber

A theoretical study is made on He scattering from three fundamental classes of disordered ad-layers: (a) Translationally random adsorbates, (b) disordered compact islands and (c) fractal submonolayers. The implications of the results to experimental studies of He scattering from disordered surfaces are discussed, and a combined experimental-theoretical study

Brian D. Serot, John Dirk Walecka

Quantum hadrodynamics (QHD) is a framework for describing the nuclear many-body problem as a relativistic system of baryons and mesons. Motivation is given for the utility of such an approach and for the importance of basing it on a local, Lorentz-invariant lagrangian density. Calculations of nuclear matter and finite nuclei in both renormalizable and nonren

S. Teis, W. Cassing, M. Effenberger, A. Hombach

We study the dynamics of charged pions in the nuclear medium via the ratio of differential $π^-$- and $π^+$-spectra in a coupled-channel BUU (CBUU) approach. The relative energy shift of the charged pions is found to correlate with the pion freeze-out time in nucleus-nucleus collisions as well as with the impact parameter of the heavy-ion reaction. Furthermo

M. Tanifuji, S. Ishikawa, Y. Iseri

The tensor analyzing power $T_{20}$ and the polarization transfer coefficients $κ_0 (= 3/2 K_y^y)$ and $K_{xz}^y$ are investigated for dp backward elastic scattering by the invariant-amplitude method. Discrepancies between the conventional calculations and the experimental data on $T_{20}$ and $κ_0$ at high and intermediate energies are mostly dissolved by i

Stanislaw J. Szarek

For a (compact) subset $K$ of a metric space and $\varepsilon > 0$, the {\em covering number} $N(K , \varepsilon )$ is defined as the smallest number of balls of radius $\varepsilon$ whose union covers $K$. Knowledge of the {\em metric entropy}, i.e., the asymptotic behaviour of covering numbers for (families of) metric spaces is important in many areas of m

Greg Hjorth

If G is a Polish group, then there is a Polish G-space X which is universal among Polish G-spaces with respect to continuous G-embeddings.

M. Kontsevich, A. Zorich

We started from computer experiments with simple one-dimensional ergodic dynamical systems called interval exchange transformations. Correlators in these systems decay as a power of time. In the simplest non-trivial case the exponent is equal to 1/3. We found a formula connecting characteristic exponents with explicit integrals over moduli spaces of algebrai

Sergio Ferrara

The role of Bertotti-Robinson geometry in the attractor mechanism of extremal black holes is described for the case of N = 2 supersymmetry. Its implication for a model-independent derivation of the Bekenstein-Hawking entropy formula is discussed.

G. Amelino-Camelia

I discuss the applicability in Weyl-invariant induced gravity and topologically massive gravity of certain formulas originally derived by Knizhnik, Polyakov, and Zamolodchikov in the context of diffeomorphism-invariant induced gravity.

M. V. Manías, C. M. Naón, M. L. Trobo

We show how to extend the standard functional approach to bosonisation, based on a decoupling change of path-integral variables, to the case in which a finite temperature is considered. As examples, in order to both illustrate and check the procedure, we derive the thermodynamical partition functions for the Thirring and Schwinger models.

M. C. Land

Despite the many successes of the relativistic quantum theory developed by Horwitz, et. al., certain difficulties persist in the associated covariant classical mechanics. In this paper, we explore these difficulties through an examination of the classical Coulomb problem in the framework of off-shell electrodynamics. As the local gauge theory of a covariant

Sergei V. Ketov

The effective low-energy hyper-K"ahler potential for a massive N=2 matter in the N=2 super-QCD is investigated. The N=2 extended supersymmetry severely restricts that N=2 matter self-couplings so that their exact form can be fixed by a few parameters, which is apparent in the N=2 harmonic superspace. In the N=2 QED with a single matter hypermultiplet, th

S. Deser

After defining the concept of duality in the context of general $n$-form abelian gauge fields in 2$n$ dimensions, we show by explicit example the difference between apparent but unrealizable duality transformations, namely those in $D=4k+2$, and those, in $D=4k$, that can be implemented by explicit dynamical generators. We then consider duality transformatio

J. Balog, M. Niedermaier

A scaling hypothesis for the n-particle spectral densities of the O(3) nonlinear sigma-model is described. It states that for large particle numbers the n-particle spectral densities are ``self-similar'' in being basically rescaled copies of a universal shape function. This can be viewed as a 2-dimensional, but non-perturbative analogue of the KNO sc

S. Kalyana Rama

We consider the effective action for strings and describe in detail the evolution of a four dimensional homogeneous isotropic universe with matter included. We find that the evolution, which is singular in general, becomes singularity free if during certain Phase of the evolution, when the scale factor increases and the effective string coupling becomes stro

Shijong Ryang

We construct the Euclidean on-shell action for the five-dimensional non-extremal black hole with multiple electric charges. We show that this thermal action agrees with one half of the entropy. This agreement is argued to be related to the generalized Smarr formula of the five-dimensional black hole mass. Through the calculation of the specific heat far off

Mirjam Cvetic

We review the macroscopic and microscopic properties of black holes of toroidally compactified heterotic and Type II string theory in dimensions 4<=D<=9. General charged rotating black hole solutions are obtained by acting on a generating solution with classical duality symmetries. In D=4, D=5 and 6<=D<=9, the generating solution for both toroidally compacti

Ian Chapman

We compare two competing theories regarding finite temperature wave-function corrections for the process $H \to e^+e^-$ and for $n+ν\to p+e^-$ and related processes of interest for primordial nucleosynthesis. Although the two methods are distinct (as shown in $H \to e^+e^-$) they yield the same finite temperature correction for all $n\to p$ and $p \to n$ pro

D. Denisov, S. Keller

We summarize the activity of the Very Large Hadron Collider Physics and Detector subgroup during Snowmass 96.

A. Ayala, J. Kapusta

We compute the influence of Coulomb effects on the charged kaon distribution at low momentum in high energy nucleus-nucleus collisions. This is accomplished by solving the Vlasov equation for the kaons in the presence of an expanding, highly charged, fireball.

T. Mannel, S. Recksiegel

We investigate the rare decay $Λ_b \to Λγ$ which receives both short and long distance contributions. We estimate the long distance contributions and find them very small. The form factors are obtained from $Λ_c \to Λ\ell \barν_\ell$ using heavy quark symmetry and a pole model. The short distance piece opens a window to new physics and we discuss the sensiti

B. Blok, M. Gronau, J. L. Rosner

A number of $B$ meson decays may proceed only through participation of the spectator quark, whether through amplitudes proportional to $f_B/m_B$ or via rescattering from other less-suppressed amplitudes. An expected hierarchy of amplitudes in the absence of rescattering will be violated by rescattering corrections. Such violations could point the way toward

Tancredi Carli

Data on the hadronic final state of deep-inelastic events at the ep collider HERA are reviewed. Fragmentation properties in the current region extracted from charged particle spectra are compared to e+e- and fixed target experiments at lower center of mass energies. A measurement of the strong coupling constant from integrated jet rates is presented and pros

T. Yanagida

We point out that a sector required to set the cosmological constant to zero in gauge-mediated supersymmetry-breaking models naturally produces a supersymmetry-invariant mass ($μ$ term) for Higgs doublets of the order of the electroweak scale. Since this new sector preserves the supersymmetry, it does not generate supersymmetry-breaking masses for the Higgs

Peter Arnold

It has recently been argued that the rate per unit volume of baryon number violation (topological transitions) in the hot, symmetric phase of electroweak theory is of the form $ηα_w^5 T^4$ in the weak-coupling limit, where $η$ is a non-perturbative numerical coefficient. Over the past several years, there have been attempts to extract the rate of baryon numb

F. Gliozzi, P. Provero

According to the Svetitsky-Yaffe conjecture, a (d+1)-dimensional pure gauge theory undergoing a continuous deconfinement transition is in the same universality class as a d-dimensional statistical model with order parameter taking values in the center of the gauge group. We show that the plaquette operator of the gauge theory is mapped into the energy operat

Alan Bross, Ana Lucia Chaves, Jesse Costa, Marvin Johnson

The time resolution for a charged particle detection is reported for a typical scintillating fiber detector instrumented with Rockwell HISTE-IV Visible Light Photon Counters. The resolution measurements are shown to agree with a simple Monte Carlo model, and the model is used to make recomendations for improved performance. In addition, the gain linearity of

Gerard Clement

We describe the analytical extension of certain static cylindrical multi--cosmic string metrics to wormhole spacetimes with only one region at spatial infinity, and investigate in detail the geometry of asymptotically Minkowskian wormhole spacetimes generated by one or two cosmic strings. We find that such wormholes tend to lengthen rather than shorten space

Ichiro Oda

Using the canonical formalism for spherically symmetric black hole inside the apparent horizon we investigate the mass inflation in the Reissner-Nordstr$\ddot o$m black hole in the framework of quantum gravity. It is shown that like in classical gravity the combination of the effects of the influx coming from the past null infinity and the outflux backscatte

Leo Brewin

A new lattice based scheme for numerical relativity will be presented. The scheme uses the same data as would be used in the Regge calculus (eg. a set of leg lengths on a simplicial lattice) but it differs significantly in the way that the field equations are computed. In the new method the standard Einstein field equations are applied directly to the lattic

Augusto Gonzalez, Ilia Mikhailov

The energy levels of an impurity center in a deep quantum well of width L and depth g are studied analytically . Renormalised perturbative series are constructed in the regions g L^ << 1 and g L^2 >> 1. Maximal binding energy and wave function deformation to a quasi-twodimensional function are found to occur at a certain L_c satisfying sqrt{g} L_c ~ 1. Simil

M. C. W. van Rossum, Igor V. Lerner, Boris L. Altshuler, Th. M. Nieuwenhuizen

The conductance distribution of metallic mesoscopic systems is considered. The variance of this distribution describes the universal conductance fluctuations, yielding a Gaussian distribution of the conductance. We calculate diagrammatically the third cumulant of this distribution, the leading deviation from the Gaussian. We confirm random matrix theory calc

C. Wolverton, Alex Zunger

The theory of phase stability in the Ni-Au alloy system is a popular topic due to the large size mismatch between Ni and Au, which makes the effects of atomic relaxation critical, and also the fact that Ni-Au exhibits a phase separation tendency at low temperatures, but measurements at high-temperature show an ordering-type short-range order. We have clarifi

B. Normand, T. M. Rice

For a system of two-chain spin ladders, the ground state for weak interladder coupling is the spin-liquid state of the isolated ladder, but is an ordered antiferromagnet (AF) for sufficiently large interactions. We generalize the bond-operator mean-field theory to describe both regimes, and to focus on the transition between them. In the AF phase near the qu

D. A. Lidar, O. Malcai, O. Biham, D. Avnir

We show that when the standard techniques for calculating fractal dimensions in empirical data (such as the box counting) are applied on uniformly random structures, apparent fractal behavior is observed in a range between physically relevant cutoffs. This range, spanning between one and two decades for densities of 0.1 and lower, is in good agreement with t

Olav F. Syljuasen, Sudip Chakravarty, Martin Greven

Analytic expressions for the correlation length temperature dependences are given for antiferromagnetic spin-1/2 Heisenberg ladders using a finite-size non-linear sigma-model approach. These calculations rely on identifying three successive crossover regimes as a function of temperature. In each of these regimes, precise and controlled approximations are for

Andrey V. Chubukov, Dirk K. Morr

We consider a two-dimensional Fermi liquid coupled to low-energy commensurate spin fluctuations. At small coupling, the hole Fermi surface is large and centered around $Q =(π,π)$. We show that as the coupling increases, the shape of the quasiparticle Fermi surface and the spin-fermion vertex undergo a substantial evolution. At strong couplings, $g \gg ω_0$,

Jens Eggers, Z. Jane Wang

We derive a multifractal model for the velocity probability density distribution function (PDF), which is valid from the inertial range to the viscous range. The model gives a continuous evolution of velocity PDFs from large to small scales. It also predicts the asymptotic form of the PDF of velocity gradients. More importantly, the model captures the crosso

R. Opher, U. F. Wichoski

Basically the only existing theories for the creation of a magnetic field B in the Universe are the creation of a seed field of order 10^{-20} G in spiral galaxy which is subsequently supposedly amplified up to the observed 10^{-6} - 10^{-5} G by a dynamo process or a seed intergalactic field of magnitude 10^{-12} - 10^{-10} G which is amplified by collapse

J. G. Skibo, C. D. Dermer, R. Schlickeiser

The beaming pattern of thermal annihilation radiation is broader than the beaming pattern produced by isotropic nonthermal electrons and positrons in the jets of radio-emitting active galactic nuclei which Compton scatter photons from an external isotropic radiation field. Thus blueshifted thermal annihilation radiation can provide the dominant contribution

C. M. Carollo, M. Franx, G. D. Illingworth, D. A. Forbes

We have analysed HST/WFPC2 F555W and F814W images for fifteen elliptical galaxies with kinematically-distinct cores. For each of them we have derived surface brightness and isophotal parameter profiles in the two bands, color maps, and radial profiles in (V-I). We have detected photometric evidence for faint stellar disks, on scales of a few tens to a few ar

F. Rembges, C. Freiburghaus, T. Rauscher, F. -K. Thielemann

Hot (explosive) hydrogen burning or the Rapid Proton Capture Process (rp-process) occurs in a number of astrophysical environments. Novae and X-ray bursts are the most prominent ones, but accretion disks around black holes and other sites are candidates as well. The expensive and often multidimensional hydro calculations for such events require an accurate p

A. Kashlinsky, J. C. Mather, S. Odenwald

We discuss a new method of estimating the cosmic infrared background (CIB) from the spatial properties of infrared maps and give the limits on the CIB from applying it to the COBE/DIRBE maps. The strongest limits are obtained at mid- to far-IR where foregrounds are bright, but smooth. If the CIB comes from matter clustered like galaxies, the smoothness of th

Daniel P. Snowden-Ifft, Andrew J. Westphal

Mica can store (for >1 Gy) etchable tracks caused by atoms recoiling from WIMPs. Because a background from fission neutrons will eventually limit this technique, a unique signature for WIMPs in ancient mica is needed. Our motion around the center of the Galaxy causes WIMPs, unlike neutrons, to enter the mica from a preferred direction on the sky. Mica is a d

F. De Paolis, G. Ingrosso, Ph. Jetzer, M. Roncadelli

The observations of microlensing events in the Large Magellanic Cloud suggest that a sizable fraction (\sim 50%) of the galactic halo is in the form of MACHOs (Massive Astrophysical Compact Halo Objects) with an average mass $\sim 0.27 M_{\odot}$, assuming a standard spherical halo model. We describe a scenario in which dark clusters of MACHOs and cold molec

Pavel Kroupa, Christopher A. Tout

We investigate the dependence of theoretically generated mass - (absolute magnitude) relations on stellar models. Using up to date physics we compute models in the mass range 0.1 < m < 1M_sun. We compare the solar-metallicity models with our older models, with recent models computed by others, and also with an empirical mass - (absolute magnitude) relation t

I. Chepelev, Y. Makeenko, K. Zarembo

We discuss properties of D-brane configurations in the matrix model of type IIB superstring recently proposed by Ishibashi, Kawai, Kitazawa and Tsuchiya. We calculate central charges in supersymmetry algebra at infinite N and associate them with one- and five-branes present in IIB superstring theory. We consider classical solutions associated with static thr

J. A. Coarasa, Ricardo A. Jimenez, Joan Sola

We compute the O(alpha_s) SUSY-QCD corrections to the W and charged Higgs mediated inclusive semi-tauonic B-decay, B->tau antineutrino_tau X. Combining the SUSY contribution with the SM result obtained from the heavy quark effective field theory, plus ordinary QCD corrections, we find that the allowed region in the (tan(beta),M_H^\pm)-plane could be signific

Yi Hu

In this paper, certain natural and elementary polygonal objects in Euclidean space, {\it the stable polygons}, are introduced, and the novel moduli spaces ${\bfmit M}_{{\bf r}, ε}$ of stable polygons are constructed as complex analytic spaces. Quite unexpectedly, these new moduli spaces are shown to be projective and isomorphic to the moduli space $\bar{\cM}

Wayne Hu, Martin White

We calculate the anisotropies in the cosmic microwave background induced by long-wavelength primordial gravitational waves in a universe with negative spatial curvature, such as are produced in the ``open inflation&#39;&#39; scenario. The impact of these results on the COBE normalization of open models is discussed.

Alexander Givental

We prove a generalized mirror conjecture for non-negative complete intersections in symplectic toric manifolds. Namely, we express solutions of the PDE system describing quantum cohomology of such a manifold in terms of suitable hypergeometric functions. Revision 03.03.97: we correct an error in Introduction.

J. L. F. Barbon, M. A. Vazquez-Mozo

We discuss Dirichlet instanton effects on type-IIB string Thermodynamics. We review some general properties of dilute D-instanton gases and use the low-energy supergravity solutions to define the normalization of the instanton measure, as well as the effects of long-range interactions. Thermal singularities in the single-instanton sector are due to tachyonic

Cesar Gomez, Rafael Hernandez

We analize instanton generated superpotentials for three dimensional N=2 supersymmetric gauge theories obtained by compactifying on S^1 N=1 four dimensional theories. In the N_f=1 case, we find that the vacua in the decompactification limit is given by the singular points of the Coulomb branch of the N=2 four dimensional theory (we also consider the massive

D. Kirkman, D. Tytler

We present the highest quality Lyman Alpha forest spectra published to date, from the QSO HS 1946+7658. The distribution of H I column densities is a power law of slope -1.5 from Log N = 12.1 - 14. This power law can extend to N = 0, because lines weaker than Log N = 12.1 do not have a large H I optical depth. Low column lines with Log N > 9 could account fo

Igor Bandos, Kurt Lechner, Alexei Nurmagambetov, Paolo Pasti

We propose a complete, d=6 covariant and kappa-symmetric, action for an M-theory five-brane propagating in D=11 supergravity background.

N. B. Demchuk, P. Yu. Kulikov, I. M. Narodetskii, Patrick J. O&#39;Donnell

An explicit relativistic light-front quark model is presented which gives the momentum transfer dependent form factors of weak hadronic currents among heavy pseudoscalar and vector mesons in the whole accessible kinematic region $ 0\leq q^2 \leq q^2_{max} $. For the numerical investigations of the $ B \to D^* l ν_l $, $ B \to ρl ν_l $, $ D\to K^* l ν_l $ and

A. R. King, J. Frank, U. Kolb, H. Ritter

We give a global analysis of mass transfer variations in low-mass X-ray binaries and cataclysmic variables whose evolution is driven by the nuclear expansion of the secondary star. We show that limit cycles caused by irradiation of the secondary by the accreting primary are possible in a large class of these binaries. In the high state the companion transfer

T. Wettig, T. Guhr, A. Schäfer, H. A. Weidenmüller

We present two pieces of evidence in support of the conjecture that the microscopic spectral density of the Dirac operator is a universal quantity. First, we compare lattice data to predictions from random matrix theory. Second, we show that the functional form of the microscopic spectral correlations remains unchanged in random matrix models which take acco

A. Kotzinian, A. Bravar, D. von Harrach

The study of the longitudinal polarization of Lambda and Lambda-bar hyperons produced in polarized deep inelastic scattering, neutrino scattering, and in Z0 decays allows to access the spin dynamics of the quark fragmentation process. Different phenomenological spin transfer mechanisms are considered and predictions for the Lambda and Lambda-bar longitudinal

Yitzhak Frishman, Jacob Sonnenschein

We analyze the question of screening versus confinement in bosonized massless QCD in two dimensions. We deduce the screening behavior of massless $SU(N_c)$ QCD with flavored fundamental fermions and fermions in the adjoint representation. This is done by computing the potential between external quarks as well as by bosonizing also the external sources and an

Jun Nishimura

We propose a method to formulate four-dimensional N=1 super Yang-Mills theory on the lattice without fine-tuning. We first show that four-dimensional Weyl fermion in a real representation, which is equivalent to Majorana fermion, can be formulated using the domain wall approach with an addition of a Majorana mass term only for the unwanted mirror fermion. Th

Noriyuki Oshimo

The supersymmetric standard model (SSM) has a CP-violating phase in its gauge-Higgs sector. This new source of CP violation induces the electric dipole moments (EDMs) of the neutron and electron at the one-loop level. The same CP-violating phase generates the EDM of the $W$ boson through one-loop diagrams mediated by the charginos and neutralinos, which lead

Nakwoo Kim, Soo-Jong Rey

M(atrix) theory on an orbifold and classical two-branes therein are studied with particular emphasis to heterotic M(atrix) theory on $S_1/Z_2$ relevant to strongly coupled heterotic and dual Type IA string theories. By analyzing orbifold condition on Chan-Paton factors, we show that three choice of gauge group are possible for heterotic M(atrix) theory: SO(2

Vadim Ponomarenko, Naoto Nagaosa

Suppression of electron current $ ΔI$ through a 1D channel of length $L$ connecting two Fermi liquid reservoirs is studied taking into account the Umklapp electron-electron interaction induced by a periodic potential. This interaction causes Hubbard gaps $E_H$ for $L \to \infty$. In the perturbative regime where $E_H \ll v_c/L$ ($v_c:$ charge velocity), and

Walter Fusseder

Widespread unjustified views on the role of the observer, the individuality of quantum processes, the relation between decoherence and irreversibility, Bell&#39;s quest for `beables&#39;, the direction of time, and the concept of experience are revealed, whereby a better understanding is achieved of what the evolutionary picture is all about and what is rega

A. Ballesteros, F. J. Herranz, M. A. del Olmo, Mariano Santander

A non-standard quantum deformation of the Poincaré algebra is presented in a null-plane framework for 1+1, 2+1 and 3+1 dimensions. Their corresponding universal $R$-matrices are obtained in a factorized form by choosing suitable bases related to the $T$-matrix formalism.

Angel Ballesteros, Francisco J. Herranz

All possible Lie bialgebra structures on the harmonic oscillator algebra are explicitly derived and it is shown that all of them are of the coboundary type. A non-standard quantum oscillator is introduced as a quantization of a triangular Lie bialgebra, and a universal $R$-matrix linked to this new quantum algebra is presented.

V. P. Akulov, V. V. Chitov, Steven Duplij

We propose the ``short&#39;&#39; version of q-deformed differential calculus on the light-cone using twistor representation. The commutation relations between coordinates and momenta are obtained. The quasi-classical limit introduced gives an exact shape of the off-shell shifting.

Th. Mausbach, Th. Klinger, A. Piel, A. Atipo

In the positive column of a neon glow discharge, two different types of ionization waves occur simultaneously. The low-dimensional chaos arising from the nonlinear interaction between the two waves is controlled by a continuous feedback technique. The control strategy is derived from the time-delayed autosynchronization method. Two spatially displaced points