May 1995 arXiv papers — page 4

Don Garnett

I review the current data on abundances in irregular galaxies, with special emphasis on recent results on C/O and Si/O from observations with the Hubble Space Telescope. The abundance data for He, C, N, and O in irregular galaxies is discussed in the context of models for the evolution of dwarf galaxies.

Wei Lu

The possibility is examined for the inclusive $Λ$ in unpolarized electron-positron annihilation to be transversely polarized. Due to final-state interactions, there exists a novel structure function $\hat F(z,Q^2)$ for the inclusive $Λ$ hyperon (or any other baryons) production from the unpolarized time-like photon fragmentation, which makes contribution to

Uros Seljak

The effect of gravitational lensing on cosmic microwave background (CMB) anisotropies is investigated using the power spectrum approach. The lensing effect can be calculated in any cosmological model by specifying the evolution of gravitational potential. Previous work on this subject is generalized to a non-flat universe and to a nonlinear evolution regime.

Paul Federbush

The Euclidean version of the Yang-Mills theory is studied in four dimensions. The field is expressed non-linearly in terms of the basic variables. The field is developed inductively, adding one excitation at a time. A given excitation is added into the ``background field'' of the excitations already added, the background field expressed in a radially

D. Elbaz, M. Arnaud, E. Vangioni-Flam

A detailed model of galactic evolution is proposed to explain both the iron content of the Intra-Cluster Medium (ICM) and of the ellipticals pertaining to the cluster. SNII are responsible for the production of Fe in the galaxies and of its partial ejection in the surrounding medium. A high formation rate of massive stars only ($m>3~{\rm M_{\sun}}$) at the v

E. Ivanov, S. Krivonos, A. Sorin

We present a manifestly $N=2$ supersymmetric formulation of $N=2$ super-$W_3^{(2)}$ algebra (its classical version) in terms of the spin 1 unconstrained supercurrent generating a $N=2$ superconformal subalgebra and the spins 1/2, 2 bosonic and spins 1/2, 2 fermionic constrained supercurrents. We consider a superfield reduction of $N=2$ super-$W_3^{(2)}$ to $

Krzysztof T. Chyzy, Stanislaw Zieba

The simple unification scheme of powerful radio galaxies and quasars, based entirely on the orientation dependent effects, has been confronted with the observed radio structures for 152 radio galaxies and 173 steep spectrum quasars. Contrary to the scheme's prediction, the cosmological evolution of geometrical parameters describing the large scale struct

L. Bonora, C. S. Xiong

We analyze the topological nature of $c=1$ string theory at the self--dual radius. We find that it admits two distinct topological field theory structures characterized by two different puncture operators. We show it first in the unperturbed theory in which the only parameter is the cosmological constant, then in the presence of any infinitesimal tachyonic p

Jasper Taylor

We have shown that belief modelling for dialogue can be simplified if the assumption is made that the participants are cooperating, i.e., they are not committed to any goals requiring deception. In such domains, there is no need to maintain individual representations of deeply nested beliefs; instead, three specific types of belief can be used to summarize a

J. Navarro-Salas, M. Navarro, C. F. Talavera

We consider the semiclassical dynamics of CGHS black holes with a Weyl-invariant effective action for conformal matter. The trace anomaly of Polyakov effective action is converted into the Virasoro anomaly thus leading to the same flux of Hawking radiation. The covariance of semiclassical equations can be restored through a non-local redefinition of the metr

I. Montvay

The effective action induced by fermions in the chiral Schwinger model with charges (3,4,5) is investigated. Pauli-Villars regularization is combined with momentum cut-off for the evaluation of the fermion determinants on continuum gauge fields interpolated between lattice points. The convergence and gauge variance are studied numerically on gauge configurat

Piotr Garbaczewski, Robert Olkiewicz

Probabilistic solutions of the so called Schrödinger boundary data problem provide for a unique Markovian interpolation between any two strictly positive probability densities designed to form the input-output statistics data for the process taking place in a finite-time interval. The key issue is to select the jointly continuous in all variables positive Fe

V. Castellani, G. Fiorentini, O. Straniero, B. Ricci

We connect the observed under-abundances of Li and Be in dwarfs, with recent results on nuclear cross sections at low energies: for collisions of protons with atomic or molecular targets, the measured cross sections seem too high with respect to extrapolations for bare nuclei. Phenomenologically, these anomalous nuclear interactions can be described in terms

R. Foot, R. R. Volkas

Evidence for $\bar ν_μ \rightarrow \bar ν_e$ oscillations has been reported at LAMPF using the LSND detector. Further evidence for neutrino mixing comes from the solar neutrino deficit and the atmospheric neutrino anomaly. All of these anomalies require new physics. We show that all of these anomalies can be explained if the standard model is enlarged so tha

T. E. Grigereit, J. W. Lynn, R. J. Cava, J. J. Krajewski

Elastic and inelastic neutron scattering measurements have been carried out to investigate the magnetic properties of superconducting (Tc~8K) HoNi2B2C. The inelastic measurements reveal that the lowest two crystal field transitions out of the ground state occurat 11.28(3) and 16.00(2) meV, while the transition of 4.70(9) meV between these two levels is obser

Paul Watts

The basics of quasitriangular Hopf algebras and quantum Lie algebras are briefly reviewed, and it is shown that their properties allow the introduction of a Killing form. For quantum Lie algebras, this leads to the definitions of a Killing metric and quadratic casimir. The specific case of $\uea{su}{N}$ is examined in detail, where it is shown that many of t

Stephen Sawin

The decomposition of an arbitrary axiomatic topological quantum field theory or TQFT into indecomposable theories is given. In particular, unitary TQFT's in arbitrary dimensions are shown to decompose into a sum of theories in which the Hilbert space of the sphere is one-dimensional, and indecomposable two-dimensional theories are classified.

H. Sorge, J. L. Nagle, B. S. Kumar

Deuteron production in S and Pb induced collisions at beam energies of 200 and 160 AGeV is studied in the framework of the transport theoretical approach RQMD. Strong transverse flow invalidates the differential coalescence formula in momentum space. The transverse momentum integrated $d$ yields scale in a broad rapidity interval with the squared proton dens

Kay Magaard, Gordan Savin

Let $G$ be a split simply laced group defined over a $p$-adic field $F$. In this paper we study the restriction of the minimal representation of $G$ to various dual pairs in $G$. For example, the restriction of the minimal representation of $E_7$ to the dual pair $G_2 \times{}$Sp(6) gives the non-endoscopic Langlands lift of irreducible representations of $G

A. A. Tseytlin

We consider a class of conformal models describing closed strings in axially symmetric stationary magnetic flux tube backgrounds. These models are closed string analogs of the Landau model of a particle in a magnetic field or the model of an open string in a constant magnetic field. They are interesting examples of solvable unitary conformal string theories

Michel Bauer, Daniel Z. Freedman

The Hamiltonian dynamics of \(2 + 1\) dimensional Yang-Mills theory with gauge group SU(2) is reformulated in gauge invariant, geometric variables, as in earlier work on the \(3 + 1\) dimensional case. Physical states in electric field representation have the product form \(Ψ_{\mathrm{phys}} [E^{a i}] = \exp ( i Ω[ E ] / g ) F [G_{ij}]\), where the phase fac

J. A. H. Samtleben

The quantized form of the soft N=8 superconformal algebra is investigated. Its operator product expansions are shown to exhibit a one-parameter-class of (soft) anomalies, which may be arbitrarily shifted by certain suitable quantum corrections of the generators. In particular, the BRST operator can be constructed and made nilpotent in the quantum version of

Serdar Nergiz, Cihan Saclioglu

We present a quasiperiodic self-dual metric of the Gibbons--Hawking type with one gravitational instanton per spacetime cell. The solution, based on an adaptation of Weierstrassian $ζ$ and $σ$ functions to three dimensions, conforms to a definition of spacetime foam given by Hawking.

J. D. Kim, H. S. Cho

We present one loop boundary reflection matrix for $d_4^{(1)}$ Toda field theory defined on a half line with the Neumann boundary condition. This result demonstrates a nontrivial cancellation of non-meromorphic terms which are present when the model has a particle spectrum with more than one mass. Using this result, we determine uniquely the exact boundary r

Giovanni M. Cicuta, Luca Molinari, Sebastiano Stramaglia

The spontaneous symmetry breaking associated to the tearing of a random surface, where large dynamical holes fill the surface, was recently analized obtaining a non-universal critical exponent on a border phase. Here the issue of universality is explained by an independent analysis. The one hole sector of the model is useful to manifest the origin of the (li

S. Kojima, N. Sakai, Y. Tanii

Quantum theory of dilaton gravity coupled to a nonlinear sigma model with a maximally symmetric target space is studied in $2+ε$ dimensions. The ultraviolet stable fixed point for the curvature of the nonlinear sigma model demands a new fixed point theory for the dilaton coupling function. The fixed point of the dilaton coupling is a saddle point similarly t

N. G. Deshpande, Xiao-Gang He

A new way of determining the phases of weak amplitudes in charged $B$ decays based on SU(3) symmetry is proposed. The CP violating phase $γ$ can now be determined without the previous difficulty associated with electroweak penguins.

F. L. Braghin, D. Vautherin, A. Abada

We investigate the role of the effective nucleon-nucleon interaction in the description of giant dipole resonances in hot nuclei. For this purpose we calculate the response function of hot nuclear matter to a small isovector external perturbation using various effective Skyrme interactions. We find that for Skyrme forces with an effective mass close to unity

Paolo Gambino

Recent developments in the field of high precision calculations in the Standard Model are illustrated with particular emphasis on the evidence for radiative corrections and on the estimate of the theoretical error in perturbative calculations.

Kingman Cheung

The recent development of perturbative QCD (PQCD) fragmentation functions has strong impact on quarkonium production. I shall summarize $B_c$ meson production based on these PQCD fragmentation functions, as well as, the highlights of some recent activities on applying these PQCD fragmentation functions to explain anomalous $J/ψ$ and $ψ'$ production at th

Nicola Di Bartolomeo

We compute the chiral corrections to the hyperfine splittings $Δ_D=(m_{D^*_s}-m_{D_s})-(m_{D^{*+}}-m_{D^+})$ and $Δ_B=(m_{B^*_s}-m_{B_s})-(m_{B^{*0}}-m_{B^0})$ arising from one-loop chiral corrections, working in a framework of an effective chiral lagrangian incorporating chiral, heavy flavour and spin symmetric terms and first order breaking terms. Among th

S. F. King

We propose a new parametrisation of the Cabibbo-Kobayashi-Maskawa Matrix in which the approximations of the standard parametrisation, $|V_{cb}|\approx s_{23}$, $|V_{us}|\approx s_{12}$, are promoted to exact results.

A. Giovannini, S. Lupia, R. Ugoccioni

The dependence of the average number of partons per clan on virtuality and rapidity variables is analytically predicted in the framework of the Generalized Simplified Parton Shower model, based on the idea that clans are genuine elementary subprocesses. The results obtained are found to be qualitatively consistent with experimental trends. This study extends

K. G. Chetyrkin, A. Kwiatkowski

Quark mass effects in ${\cal O}(α_s^2)$ QCD corrections to the decay rates of intermediate Higgs bosons are studied. The total hadronic rate and the partial decay rate into bottom quarks are analyzed for the Standard (scalar) Higgs boson as well as for pseudoscalar Higgs bosons. The calculations of three different contributions are presented. First, the flav

Urs M. Heller, ; Frithjof Karsch, Joern Rank

We study the gluon propagator in Landau gauge in the deconfined phase of $SU(2)$ gauge theory. From the long-distance behaviour of correlation functions of temporal and spatial components of the gauge fields we extract electric ($m_e$) and magnetic ($m_m$) screening masses. For temperatures larger than twice $T_c$ we find no additional temperature dependence

Johannes Huebschmann

Let $Y$ be a CW-complex with a single 0-cell, let $K$ be its Kan group, a free simplicial group whose realization is a model for the space $ΩY$ of based loops on $Y$, and let $G$ be a Lie group, not necessarily connected. By means of simplicial techniques involving fundamental results of {\smc Kan's} and the standard $W$- and bar constructions, we obtain

Michael HILKE

The localization properties of a two-dimensional disordered electron gas in a strong external magnetic field are studied. The impurities are considered to be located on a square lattice with random amplitudes. The concentration of these impurities is low, i.e., the average distance between the impurities exceeds the magnetic length. For short-ranged impurity

Fernando Moraes

In the framework of the theory of defects/three-dimensional gravitation, it is obtained a positive correction to the magnetic moment of the electron bound to a disclination in a dielectric solid.

Kent Baekgaard Lauritsen

A growth equation with a generalized conservation law characterized by an integral kernel is introduced. The equation contains the Kardar-Parisi-Zhang, Sun-Guo-Grant, and Molecular-Beam Epitaxy growth equations as special cases and allows for a unified investigation of growth equations. From a dynamic renormalization-group analysis critical exponents and uni

Ganpathy Murthy, R. Shankar

We discuss a {\em family} of planar (two-dimensional) systems with the following phase strucure: a Fermi liquid, which goes by a second order transition (with non classical exponent even in mean-field) to an intermediate, inhomogeneous state (with nonstandard ordering momentum) , which in turn goes by a first order transition to a state with canonical order

C. Kübert, A. Muramatsu

We study a doped antiferromagnet (AF) using a rotating reference-frame. Whereas in the laboratory reference-frame with a globally fixed spin-quantization axis (SQA) the long-wavelength, low-energy physics is given by the O(3) non-linear $σ$-model with current-current interactions between the fermionic degrees of freedom and the order-parameter field for the

N. B. Ivanov, S. E. Krüger, J. Richter

We study the zero-temperature phase diagram of a square-lattice $S=1/2$ Heisenberg antiferromagnet with two types of regularly distributed nearest-neighbor exchange constants, $J_1>0$ (antiferromagnetic) and $-\infty < J_2 < \infty $, using spin-wave series based on appropriate mean-field Hamiltonian and exact-diagonalization data for small clusters. At a qu

J. Müllers, A. Schmid

A field theoretical method is developed which permits us to study the dynamics of vortices in disordered environments. In particular, we obtain a self-consistent system of equations for disorder averaged quantities. Making use of a Hartree-type approximation, we calculate the current-voltage (I-V) characteristics in the flux flow regime. In order to probe in

A. Levy Yeyati, A. Martín-Rodero, J. C. Cuevas

The exact expression for the phase-dependent linear conductance of a weakly damped superconducting quantum point contact is obtained. The calculation is performed by summing up the complete perturbative series in the coupling between the electrodes. The failure of any finite order perturbative expansion in the limit of small voltage and small quasi-particle

Yigal Meir

The magnetoresistance in the variable-range hopping regime due to Zeeman spin-splitting and intra-impurity interactions is calculated analytically and shown to be a universal function of $μH / kT \log R$. Good agreement with numerical calculations in one and two dimensions is observed. With the inclusion of quantum interference effects, excellent agreement w

Per Frojdh, Henrik Johannesson

We report on exact results for the low-temperature thermodynamics of a spin-$\frac{1}{2}$ magnetic impurity coupled to a one-dimensional interacting electron system. By using boundary conformal field theory, we show that there are only two types of critical behaviors consistent with the symmetries of the problem: {\em either} a local Fermi liquid, {\em or} a

James Rogers

We introduce $L^2_{K,P}$, a monadic second-order language for reasoning about trees which characterizes the strongly Context-Free Languages in the sense that a set of finite trees is definable in $L^2_{K,P}$ iff it is (modulo a projection) a Local Set---the set of derivation trees generated by a CFG. This provides a flexible approach to establishing language

Lance A. Ramshaw, Mitchell P. Marcus

Eric Brill introduced transformation-based learning and showed that it can do part-of-speech tagging with fairly high accuracy. The same method can be applied at a higher level of textual interpretation for locating chunks in the tagged text, including non-recursive ``baseNP&#39;&#39; chunks. For this purpose, it is convenient to view chunking as a tagging p

Katashi Nagao, Jun Rekimoto

Augmented reality is a research area that tries to embody an electronic information space within the real world, through computational devices. A crucial issue within this area, is the recognition of real world objects or situations. In natural language processing, it is much easier to determine interpretations of utterances, even if they are ill-formed, whe

Bruce M. Boghosian

Euler turbulence has been experimentally observed to relax to a metaequilibrium state that does not maximize the Boltzmann entropy, but rather seems to minimize enstrophy. We show that a recent generalization of thermodynamics and statistics due to Tsallis is capable of explaining this phenomenon in a natural way. The maximization of the generalized entropy

Pedro Colin

A newly developed isochrone synthesis algorithm for the photometric evolution of galaxies is described. Two initial mass functions, IMFs, in particular, the recent IMF determined by Kroupa, Tout, and Gilmore, three photometric transformations, and a 1-Gyr-burst star formation rate, SFR, are used to compute the $B-V$ and $V-K$ color index evolution. Non-negli

Francesco Sylos Labini

A distribution of points that satisfies the property of local isotropy is not necessarily homogeneous: homogeneity is implied by the condition of local isotropy together with the assumption of analyticity or regularity. Here we show that the evidence of dipole saturation in galaxies (and clusters) catalogues, together with a monotone growth of the monopole,

Saleem Zaroubi

The formalism of Wiener filtering is applied to reconstruct, in terms of spherical harmonics, the projected $4π$ galaxy distribution of a mock IRAS 1.2 Jy catalog with a `Zone of Avoidance&#39; $|b| = 15^\circ$. The Singular Value Decomposition al gorithm is utilized as an extra-regularizer in order to stabilize the inversion. This case sheds light on the am

R. Pandharipande

A compactification over $\overline{M}_g$ of $M_{g,n}$ is obtained by considering the relative Fulton-MacPherson configuration space of the universal curve. The resulting compactification differs from the Deligne-Mumford space $\overline{M}_{g,n}$. In case $n=2$, the compactification constructed here and the Deligne-Mumford compactification are essentially th

Fabrizio Catanese, Klaus Hulek

The families of smooth rational surfaces in $\PP^4$ have been classified in degree $\le 10$. All known rational surfaces in $\PP^4$ can be represented as blow-ups of the plane $\PP^2$. The fine classification of these surfaces consists of giving explicit open and closed conditions which determine the configurations of points corresponding to all surfaces in

Scott Chapman, J. Rayford Nix, Ulrich Heinz

Using a quadratic saddle-point approximation, we show how information about a particle-emitting source can be extracted from gaussian fits to two-particle correlation data. Although the formalism is completely general, extraction of the relevant parameters is much simpler for sources within an interesting class of azimuthally symmetric models. After discussi

Dmitrii L. Maslov, Michael Stone

We show that the dc conductance of a quantum wire containing a Luttinger liquid and attached to non-interacting leads is given by $e^2/h$ per spin orientation, regardless of the interactions in the wire. This explains the recent observations of the absence of conductance renormalization in long high-mobility $GaAs$ wires by Tarucha, Honda and Saku (Solid Sta

C. Gomez, E. Lopez

For $N\!=\!2$ SUSY theories with non-vanishing $β$-function and one-dimensional quantum moduli, we study the representation on the special coordinates of the group of motions on the quantum moduli defined by $Γ_W\!=\!Sl(2;Z)\!/\!Γ_M$, with $Γ_M$ the quantum monodromy group. $Γ_W$ contains both the global symmetries and the strong-weak coupling duality. The a

J. Loveday, G. Efstathiou, S. J. Maddox, B. A. Peterson

Galaxy redshift surveys provide a distorted picture of the universe due to the non-Hubble component of galaxy motions. By measuring such distortions in the linear regime one can constrain the quantity $β= Ω^{0.6}/b$ where $Ω$ is the cosmological density parameter and $b$ is the (linear) bias factor for optically-selected galaxies. In this paper we apply two

Gautam Bhattacharyya, Amitava Raychaudhuri

In the context of the left--right symmetric model, the decay $b \rightarrow s γ$ receives contributions from the gauge interactions mediated mainly by the $W_L$, through $W_L$--$W_R$ mixing and also from the Yukawa interactions of the charged and the neutral (flavour-changing) scalars (the latter type of Yukawa interaction has been overlooked in the previous

B. Holdom, G. Triantaphyllou

Previous results on fermion chirality-flipping four-point functions are extended to $SU(N)$ gauge theories. The problem is purely non-perturbative, and it is approached by truncating the Schwinger-Dyson hierarchy. The large-$N$ limit also simplifies the problem substantially. The resulting equation is solved numerically by relaxation techniques and an estima

B. Sathiapalan

It is known that there is a proportionality factor relating the $β$-function and the equations of motion viz. the Zamolodchikov metric. Usually this factor has to be obtained by other methods. The proper time equation, on the other hand, is the full equation of motion. We explain the reasons for this and illustrate it by calculating corrections to Maxwell&#3

Ana Achucarro, Ruth Gregory, Konrad Kuijken

We find evidence for the existence of solutions of the Einstein and Abelian Higgs field equations describing a black hole pierced by a Nielsen-Olesen vortex. This situation falls outside the scope of the usual no-hair arguments due to the non-trivial topology of the vortex configuration and the special properties of its energy-momentum tensor. By a combinati

Arnd Brandenburg, Lance Dixon, Yael Shadmi

We discuss rescattering effects that can be measured in $e^+e^-$ annihilation to three jets through a single gauge boson, by using triple product (``event handedness&#39;&#39;) correlations of the $Z$ ($γ^*$) polarization with jet momenta. The gauge boson polarization may be produced either by polarized beams or through the natural polarization (left-right a

C. Rasinariu, U. Sukhatme, Avinash Khare

We give a systematic classification and a detailed discussion of the structure, motion and scattering of the recently discovered negaton and positon solutions of the Korteweg-de Vries equation. There are two distinct types of negaton solutions which we label $[S^{n}]$ and $[C^{n}]$, where $(n+1)$ is the order of the Wronskian used in the derivation. For nega

I. L. Chuang, Y. Yamamoto

We propose an implementation of a quantum computer to solve Deutsch&#39;s problem, which requires exponential time on a classical computer but only linear time with quantum parallelism. By using a dual-rail qubit representation as a simple form of error correction, our machine can tolerate some amount of decoherence and still give the correct result with hig

Edward Frenkel, Nikolai Reshetikhin

We generalize some results concerning affine algebras at the critical level to the corresponding quantum algebras. In particular, we show that the Wakimoto realization provides a homomorphism of Poisson algebras from the center of a quantum affine algebra to a Heisenberg-Poisson algebra. This homomorphism is a q-deformation of the Miura transformation. It is

Prashant M. Gade, Hilda A. Cerdeira, R. Ramaswamy

We study coupled maps on a Cayley tree, with local (nearest-neighbor) interactions, and with a variety of boundary conditions. The homogeneous state (where every lattice site has the same value) and the node-synchronized state (where sites of a given generation have the same value) are both shown to occur for particular values of the parameters and coupling

V. S. Uma Maheswari, V. S. Ramamurthy, L. Satpathy

A comparative study of the liquid-drop model (LDM) type expansions of energy $E$ and compression modulus $K_A$ is made within the energy density formalism using Skyrme interactions. As compared to the energy expansion, it is found that, in the pure bulk mode of density vibration, the LDM expansion of $K_A$ shows an anomalous convergence behaviour due to {\it

G. Amelino-Camelia, D. Bak, D. Seminara

We investigate the gauge-independent Hamiltonian formulation and the anomalous Ward identities of a matter-induced 1+1-dimensional gravity theory invariant under Weyl transformations and area-preserving diffeomorphisms, and compare the results to the ones for the conventional diffeomorphism-invariant theory. We find that, in spite of several technical differ

J. Maeder, W. Ruehl

O(N) vector sigma models possessing catastrophes in their action are studied. Coupling the limit N --> infinity with an appropriate scaling behaviour of the coupling constants, the partition function develops a singular factor. This is a generalized Airy function in the case of spacetime dimension zero and the partition function of a scalar field theory for

Detlev Buchholz

For any given algebra of local observables in relativistic quantum field theory there exists an associated scaling algebra which permits one to introduce renormalization group transformations and to construct the scaling (short distance) limit of the theory. On the basis of this result it is discussed how the phase space properties of a theory determine the

M. Goodband, M. Hindmarsh

We investigate the instabilities of low winding number electroweak strings using standard numerical techniques of linear algebra. For strings of unit winding we are able to confirm and extend existing calculations of the unstable region in the ($m_H/m_W,\sin^2θ_W$) plane. For strings of higher winding number we map the unstable regions for the various decay

M. Gremm, F. Krüger, L. M. Sehgal

We study the angular distribution of photons produced in the inclusive decay of a polarized $Λ_b$, $Λ_b\to X_s\,γ$, using the technique of Heavy Quark Effective Theory. Finite non-perturbative corrections are obtained relative to the free quark decay $b\to sγ$. These corrections affect significantly the intensity and polarization of photons emitted at small

R. B. Mann, U. Sarkar

We consider the hypothesis that neutrino oscillation data can be explained if the gravitational couplings of (massless or degenerate mass) neutrinos are flavour non--diagonal, in violation of the equivalence principle. We analyze the various neutrino oscillation laboratory experimental data including the recent LSND observations to constrain the relevant par

Douglas M. Eardley, Eric W. Hirschmann, James H. Horne

We study gravitational collapse of the axion/dilaton field in classical low energy string theory, at the threshold for black hole formation. A new critical solution is derived that is spherically symmetric and continuously self-similar. The universal scaling and echoing behavior discovered by Choptuik in gravitational collapse appear in a somewhat different

Stephen Sawin

A positive, diffeomorphism-invariant generalized measure on the space of metrics of a two-dimensional smooth manifold is constructed. We use the term generalized measure analogously with the generalized measures of Ashtekar and Lewandowski and of Baez. A family of actions is presented which, when integrated against this measure, give the two-dimensional axio

M. C. Bento, O. Bertolami

We discuss the main cosmological implications of considering string-loop effects and a potential for the dilaton in the lowest order string effective action. Our framework is based on the effective model arising from regarding homogeneous and isotropic dilaton, metric and Yang-Mills field configurations. The issues of inflation, entropy crisis and the Polony

K. Musaelian, Robert Joynt

We demonstrate that the two-dimensonal electron system in a strong perpendicular magnetic field has stable states which break rotational but not translational symmetry. The Laughlin fluid becomes unstable to these states in quantum wells whose thickness exceeds a critical value which depends on the electron density. The order parameter at 1/3 reduced density

A. BARDAS, D. AVERIN

We have calculated the heat current in the normal metal/insulator/ superconductor contacts with arbitrary transparency of the insulator barrier. In the tunneling limit (small transparencies), the heat flow out of the normal metal reaches its maximum at temperature $T\simeq 0.3Δ$. At higher values of transparency, the interplay between single-particle tunneli

D. AVERIN, A. BARDAS

We have calculated all the components of the current in a short one-dimensional channel between two superconductors for arbitrary voltages and transparencies $D$ of the channel. We demonstrate that in the ballistic limit ($D\simeq 1$), the crossover between the quasistationary evolution of the Josephson phase difference $φ$ at small voltages and transport by

R. A. Hyman, Kun Yang, R. N. Bhatt, S. M. Girvin

We study the effects of random bonds on spin chains that have an excitation gap in the absence of randomness. The dimerized spin-1/2 chain is our principal example. Using an asymptotically exact real space decimation renormalization group procedure, we find that dimerization is a relevant perturbation at the random singlet fixed point. For weak dimerization,

Kevin E. Bassler, Zoltan Racz

Monte Carlo simulations are used to show that the steady state of the d=2, two-temperature, diffusive XY model displays a continuous phase transition from a homogeneous disordered phase to a phase with long-range order. The long-range order exists although both the dynamics and the interactions are local, thus indicating the failure of a naive extension of t

B. Lopez, M. Schroeder, M. Opper

We calculate the storage capacity of a perceptron for correlated gaussian patterns. We find that the storage capacity $α_c$ can be less than 2 if similar patterns are mapped onto different outputs and vice versa. As long as the patterns are in general position we obtain, in contrast to previous works, that $α_c \geq 1$ in agreement with Cover&#39;s theorem.

Sebastian Eggert, Ian Affleck

Non-magnetic impurities in an S=1/2 Heisenberg antiferromagnetic chain are studied using boundary conformal field theory techniques and finite-temperature quantum Monte Carlo simulations. We calculate the static structure function, S_imp(k), measured in neutron scattering and the local susceptibility, chi_i measured in Knight shift experiments. S_imp(k) beco

Reinhard Rapp

Common algorithms for sentence and word-alignment allow the automatic identification of word translations from parallel texts. This study suggests that the identification of word translations should also be possible with non-parallel and even unrelated texts. The method proposed is based on the assumption that there is a correlation between the patterns of w

Douglas Scott, Martin White

The study of anisotropies in the Cosmic Microwave Background radiation is progressing at a phenomenal rate, both experimentally and theoretically. These anisotropies can teach us an enormous amount about the way that fluctuations were generated and the way they subsequently evolved into the clustered galaxies which are observed today. In particular, on sub-d

D. M. Christodoulou, D. Kazanas, I. Shlosman, J. E. Tohline

We use a free-energy minimization approach to describe the secular and dynamical instabilities as well as the bifurcations along equilibrium sequences of rotating, self-gravitating fluid systems. Our approach is fully nonlinear and stems from the Landau-Ginzburg theory of phase transitions. Here we examine higher than 2nd-harmonic disturbances applied to Mac

S. Mohanty, A. R. Prasanna

Einstein&#39;s theory predicts that, massive test particles with non-zero spin or angular momentum, in an external gravitation field, follow geodesics which depend upon the orientation of the spin-angular momentum . It has been claimed that such an effect also holds for photons i.e. photons with different helicities follow different geodesics in the gravitat

L. Ciotti, M. Stiavelli, A. Braccesi

We address the problem of deriving, from the observed projected metallicity gradients, the intrinsic metallicity distribution of elliptical galaxies as a function of their integrals of motion. The method is illustrated by an application to anisotropic spherical Hernquist models. We also compare the derived metallicity distribution with those expected from tw

S. Schindler, L. Guzzo, H. Ebeling, H. Böhringer

We report the discovery of two bright arcs in what turns out to be the brightest X--ray cluster in the ROSAT band ever observed, RXJ1347.5-1145. Its luminosity is $(6.2\pm0.6) \cdot10^{45}$erg s$^{-1}$ (in the range 0.1--2.4~keV). The arcs are most probably gravitationally lensed images of background galaxies. They were found serendipitously during our ongoi

Bohdan Paczynski

The positions of over 1000 gamma-ray bursts detected with the BATSE experiment on board of the Compton Gamma Ray Observatory are uniformly and randomly distributed in the sky, with no significant concentration to the galactic plane or to the galactic center. The strong gamma-ray bursts have an intensity distribution consistent with a number density independe

S. K. Kauffmann

The Feynman-Garrod path integral representation for time evolution is extended to arbitrary one-parameter continuous canonical transformations. One thereupon obtains a generalized Kerner-Sutcliffe formula for the unique quantum representation of the transformation generator, which can be an arbitrary classical dynamical variable. This closed-form quantizatio

Camillo Imbimbo, Sunil Mukhi

We derive a Kontsevich-type matrix model for the c=1 string directly from the W-infinity solution of the theory. The model that we obtain is different from previous proposals, which are proven to be incorrect. Our matrix model contains the Penner and Kontsevich cases, and we study its quantum effective action. The simplicity of our model leads to an encourag

A. K. Motovilov

The spectral problem $(A + V(z))ψ=zψ$ is considered with $A$, a self-adjoint Hamiltonian of sufficiently arbitrary nature. The perturbation $V(z)$ is assumed to depend on the energy $z$ as resolvent of another self-adjoint operator $A&#39;:$ $V(z)=-B(A&#39;-z)^{-1}B^{*}$. It is supposed that operator $B$ has a finite Hilbert-Schmidt norm and spectra of opera

A. K. Motovilov

A proof is given for the explicit representations which have been formulated in the author&#39;s previous work (nucl-th/9505028) for the Faddeev components of three-body T-matrix continued analytically on unphysical sheets of the energy Riemann surface. Also, the analogous representations for analytical continuation of the three-body scattering matrices and

A. K. Motovilov

Explicit representations are formulated for the Faddeev components of three-body T-matrix continued analytically on unphysical sheets of the energy Riemann surface. According to the representations, the T-matrix on unphysical sheets is obviously expressed in terms of its components taken on the physical sheet only. The representations for T-matrix are used t

Christopher Golé, Ron Karidi

We show that strictly abnormal geodesics arise in graded nilpotent Lie groups. We construct such a group, for which some Carnot geodesics are strictly abnormal; in fact, they are not normal in any subgroup. In the step-2 case we also prove that these geodesics are always smooth. Our main technique is based on the equations for the normal and abnormal curves,

S. K. Kauffmann

The self-gravitational correction of the ultraviolet-divergent second- order &#34;vacuum polarization&#34; radiative correction insertion Feynman diagram is carried out using full, self-consistent Einstein equation propagation of the intermediate virtual gravitons, which takes into account their important non-linear interactions with each other. (As a by-pro

A. A. Tseytlin

We consider analogs of Yang-Mills theories for non-semisimple real Lie algebras which admit invariant non-degenerate metrics. These 4-dimensional theories have many similarities with corresponding WZW models in 2 dimensions and Chern-Simons theories in 3 dimensions. In particular, the quantum effective action contains only 1-loop term with the divergent part