May 1994 arXiv papers — page 9

Bruce Allen, Paul Casper

We present a new formula for the rate at which cosmic strings lose energy into gravitational radiation, valid for all piecewise-linear cosmic string loops. At any time, such a loop is composed of $N$ straight segments, each of which has constant velocity. Any cosmic string loop can be arbitrarily-well approximated by a piecewise-linear loop with $N$ sufficie

R. Moessner, M. Trodden

We present a class of theories of two dimensional gravity which admits homogeneous and isotropic solutions that are nonsingular and asymptotically approach a FRW matter dominated universe at late times. These models are generalizations of two dimensional dilaton gravity and both vacuum solutions and those including conformally coupled matter are investigated

Renaud Parentani, Tsvi Piran

We present a semi-classical model for the formation and evaporation of a four dimensional black hole. We solve the equations numerically and obtain solutions describing the entire the space-time geometry from the collapse to the end of the evaporation. The solutions satisfy the evaporation law: $\dot M \propto -M^{-2}$ which confirms dynamically that black h

F. Lesage, V. Pasquier, D. Serban

We compute the dynamical Green function and density-density correlation in the Calogero-Sutherland model for all integer values of the coupling constant. An interpretation of the intermediate states in terms of quasi-particles is found.

Andrew Chamblin, Gary Gibbons, Alan R. Steif

We show that it is not possible to smooth out the metric on the Deutsch-Politzer time machine to obtain an everywhere non-singular asymptotically flat Lorentzian metric.

L. Bonora, C. S. Xiong

We show that the most general two--matrix model with bilinear coupling underlies $c=1$ string theory. More precisely we prove that $W_{1+\infty}$ constraints, a subset of the correlation functions and the integrable hierarchy characterizing such two--matrix model, correspond exactly to the $W_{1+\infty}$ constraints, to the discrete tachyon correlation funct

Jens Hoppe

A certain class of surface motions, including those of a relativistic membrane minimizing the 3-dimensional volume swept out in Minkowski-space, is shown to be equivalent to 3-dimensional steady-state irrotational inviscid isentropic gas-dynamics. The SU($\infty $) Nahm equations turn out to correspond to motions where the time $t$ at which the surface moves

Ken Yee

We (try to) pedagogically explain how monopoles arise in QCD, why maximal Abelian(MA) gauge is ``special'' for monopole study, the Abelian projection in MA gauge, its resultant degrees of freedom(photons, monopoles and charged matter fields), and the QCD-equivalent action in terms of these degrees of freedom. Then we turn to more recent developments

Kei-Ichi Kondo, Toru Ebihara, Takuya Iizuka, Eiji Tanaka

In the (2+1)-dimensional QED with and without the Chern-Simons term, we find the non-local gauge in which there is no wavefunction renormalization for the fermion in the framework of the Schwinger-Dyson equation. By solving the Schwinger-Dyson equation in the non-local gauge, we find a finite critical value $N_f^c$ for the number of flavors $N_f$ of four-com

A. P. Balachandran, L. Chandar

't Hooft has recently developed a discretisation of (2+1) gravity which has a multiple-valued Hamiltonian and which therefore admits quantum time evolution only in discrete steps. In this paper, we describe several models in the continuum with single-valued equations of motion in classical physics, but with multiple-valued Hamiltonians. Their time displa

John M. Lee

The main result of this paper is that the identity component of the automorphism group of a compact, connected, strictly pseudoconvex CR manifold is compact unless the manifold is CR equivalent to the standard sphere. In dimensions greater than 3, it has been pointed out by D. Burns that this result follows from known results on biholomorphism groups of comp

A. GHOSH, P. MITRA

The scattering of massless fermions off magnetically charged dilatonic black holes is reconsidered and a violation of unitarity is found. Even for a single species of fermion it is possible for a particle to disappear into the black hole with its information content.

A. Gerasimov, S. Khoroshkin, D. Lebedev, A. Mironov

This paper begins investigation of the concept of ``generalized $τ$-function'', defined as a generating function of all the matrix elements of a group element $g \in G$ in a given highest-weight representation of a universal enveloping algebra ${\cal G}$. In the generic situation, the time-variables correspond to the elements of maximal nilpotent sub

Harold Widom

In the bulk scaling limit of the Gaussian Unitary Ensemble of Hermitian matrices the probability that an interval of length $s$ contains no eigenvalues is the Fredholm determinant of the sine kernel $\sin(x-y)\overπ(x-y)$ over this interval. A formal asymptotic expansion for the determinant as $s$ tends to infinity was obtained by Dyson. In this paper we rep

D. K. Park

The spin-1/2 Aharonov-Bohm problem is examined in the Galilean limit for the case in which a Coulomb potential is included. It is found that the application of the self-adjoint extension method to this system yields singular solutions only for one-half the full range of flux parameter which is allowed in the limit of vanishing Coulomb potential. Thus one has

Jacobus Verbaarschot

As was shown by Leutwyler and Smilga, the fact that chiral symmetry is broken and the existence of a effective finite volume partition function leads to an infinite number of sum rules for the eigenvalues of the Dirac operator in QCD. In this paper we argue these constraints, together with universality arguments from quantum chaos and universal conductance f

J. J. M. Verbaarschot, I. Zahed

We suggest that the spectral properties near zero virtuality of three dimensional QCD, follow from a Hermitean random matrix model. The exact spectral density is derived for this family of random matrix models both for even and odd number of fermions. New sum rules for the inverse powers of the eigenvalues of the Dirac operator are obtained. The issue of ano

Vladimir Dotsenko, Marco Picco, Pierre Pujol

We compute the combined two and three loop order correction to the spin-spin correlation functions for the 2D Ising and q-states Potts model with random bonds at the critical point. The procedure employed is the renormalisation group approach for the perturbation series around the conformal field theories representing the pure models. We obtain corrections f

G. Lopes Cardoso, D. Luest, T. Mohaupt

We present the coset structure of the untwisted moduli space of heterotic $(0,2) \; Z_N$ orbifold compactifications with continuous Wilson lines. For the cases where the internal 6-torus $T_6$ is given by the direct sum $T_4 \oplus T_2$, we explicitly construct the Kähler potentials associated with the underlying 2-torus $T_2$. We then discuss the transforma

Jose Wudka

In this set of lectures I will present an elementary introduction to the uses of effective lagrangians in the electroweak interaction with emphasis in practical applications

Brian H. Smith, M. B. Voloshin

We discuss the effects of QCD corrections to the on-shell decay $t \to b W$. We resolve the scale ambiguity using the Brodsky-Lepage-Mackenzie scheme, and find that the appropriate coupling constant is $α_{s}^{ \overline{MS}} (0.122m_{t})$. The largest long distance contribution comes from the definition of the on-shell mass of the top quark. We note that QC

Jose Wudka

The effective lagrangian parametrization is used to determine the CP violating effects in $ γγ$ collisions. for the processes studied the effects are found to be very small, the one exception being scalar production.

X. Jin, M. Nielsen, J. Pasupathy

The proton matrix element of the isovector-scalar density, $<p|\overline{u}u-\overline{d}d|p>/2M_p$, is calculated by evaluating the nucleon current correlation function in an external isovector-scalar field using the QCD sum-rule method. In addition to the usual chiral and gluon condensates of the QCD vacuum, the response of the chiral condensates to the ex

M. Martinez, F. Teubert

The effect coming from imaginary parts of effective couplings in the $e^+ e^-$ asymmetries is investigated. It is shown that for the present level of experimental accuracy, in some asymmetries the imaginary parts of the effective couplings cannot be neglected and moreover that the use of different prescriptions on how to handle them in quoting just real effe

D. Choudhury, F. Cuypers, A. Leike

Model independent constraints on the mass of an extra neutral gauge boson and its couplings to charged leptons are given for the $e^-e^-$ option of a future linear collider. Analytic exclusion limits are derived in the Born approximation. The results are compared with those of the $e^+e^-$ mode. The influence of radiative corrections is discussed.

V. Barger, M. S. Berger, P. Ohmann

There has been much discussion in the literature about applying the radiative electroweak symmetry breaking (EWSB) requirement to GUT models with supergravity. We motivate and discuss the application of the EWSB requirement to the low $\tanβ$ fixed-point region and describe the solutions we find.

Artan Boriçi, Philippe de Forcrand

Different recently developed Krylov space methods for solving linear systems are studied and compared for the solution of the Dirac equation on the lattice. Stabilized Biconjugate Gradient (BiCGstab2) is shown to be a robust and efficient solver for the calculation of the Wilson quark propagator in lattice QCD.

J. A. Smoller, A. G. Wasserman

The ADM masses of particle-like solutions to the Einstein-Yang/Mills Equations tend to 2 as the number of nodes of the solutions increases. The same result is true for black hole solutions with event horizon less than 1. For event horizon $ρ> 1$ the ADM masses converge to $ρ+ ρ^{-1} .$ These statements extend and correct ``An Investigation at the Limiting Be

Peter Peldan

Two gauge and diffeomorphism invariant theories on the Yang-Mills phase space are studied. They are based on the Lie-algebras $so(1,3)$ and $\widetilde{so(3)}$ -- the loop-algebra of $so(3)$. Although the theories are manifestly real, they can both be reformulated to show that they describe complex gravity and an infinite number of copies of complex gravity,

Ruy Exel

We introduce the notion of continuous twisted partial actions of a locally compact group on a C*-algebra. With such, we construct an associated C*-algebraic bundle called the semidirect product bundle. Our main theorem shows that, given any C*-algebraic bundle which is second countable and whose unit fiber algebra is stable, there is a continuous twisted par

K. C. Ung, S. Mazumdar, D. Toussaint

The theory of the 2k_F and 4k_F instabilities in quarter-filled band organic conductors is revisited. The phase angles of the 2k_F bond and charge density waves are shown to change as electron correlation is turned on, and this switching of the phase angle is critical for understanding the bond distortion patterns in the real materials. Intersite Coulomb int

J. J. Rodríguez-Núñez, S. Schafroth, T. Schneider, M. H. Pedersen

The problem of crossover from BCS to Bose-Einstein condensation has recently attracted considerable interest owing to the discovery of high-$T_{\rm c}$ cuprates. Their short coherence length, $ξ$, places these materials in the interesting region between BCS and Bose-Einstein condensation. In the paper of F. Pistolesi and G.C. Strinati (Phys. Rev. B {\bf 49},

Yadin Y. Goldschmidt

We develop a new variational scheme to approximate the position dependent spatial probability distribution of a zero dimensional manifold in a random medium. This celebrated &#39;toy-model&#39; is associated via a mapping with directed polymers in 1+1 dimension, and also describes features of the commensurate-incommensurate phase transition. It consists of a

Julia Hirschberg

A by-no-means-complete collection of references for those interested in intonational meaning, with other miscellaneous references on intonation included. Additional references are welcome, and should be sent to julia@research.att.com.

Andrew Kehler

The temporal relations that hold between events described by successive utterances are often left implicit or underspecified. We address the role of two phenomena with respect to the recovery of these relations: (1) the referential properties of tense, and (2) the role of temporal constraints imposed by coherence relations. We account for several facets of t

Ido Dagan, Fernando Pereira, Lillian Lee

In many applications of natural language processing it is necessary to determine the likelihood of a given word combination. For example, a speech recognizer may need to determine which of the two word combinations ``eat a peach&#39;&#39; and ``eat a beach&#39;&#39; is more likely. Statistical NLP methods determine the likelihood of a word combination accord

J. -P. Eckmann, C. -A. Pillet

For a bounded open domain $Ω$ with connected complement in ${\bf R}^2$ and piecewise smooth boundary, we consider the Dirichlet Laplacian $-Δ_Ω$ on $Ω$ and the S-matrix on the complement $Ω^c$. We show that the on-shell S-matrices ${\bf S}_k$ have eigenvalues converging to 1 as $k\uparrow k_0$ exactly when $-Δ_Ω$ has an eigenvalue at energy $k_0^2$. This inc

Lawrence M. Krauss, Peter J. Kernan

A new observation of D in a primordial gas cloud, made using the high resolution spectrograph at the Keck telescope, indicates an abundance $ D/H =(1.9-2.5) \times 10^{-4}$ \cite{SCHR}. Since deuterium is destroyed by stars, and the predicted Big Bang Nucleosynthesis (BBN) abundance falls monotonically with increasing baryon density, deuterium places a relia

Anatoly Klypin, Stefano Borgani, Jon Holtzman, Joel Primack

Although the Cold + Hot Dark Matter (CHDM) cosmology provides perhaps the best fit of any model to all the available data at the current epoch, CHDM produces structure at relatively low redshifts and thus could be ruled out if there were evidence for formation of massive objects at high redshifts. Damped Ly$α$ systems are abundant in quasar absorption spectr

Uros Seljak

We compute the fluctuations in gravitational lens image positions and time delay caused by large scale structure correlations. We show that these fluctuations can be expressed as a simple integral over the density power spectrum. Using the {\sl COBE} normalization we find that positions of objects at cosmological distances are expected to deviate from their

S. Ghigna, S. A. Bonometto, L. Guzzo, R. Giovanelli

We discuss the effects of redshift--space distortions on the estimate of high order galaxy correlation functions. We use both the Perseus--Pisces redshift survey and the results of high--resolution N--body simulations to explore the consequences of working in redshift space on the detection of deviations from hierarchical clustering. Both for real and simula

Joseph A. Minahan, Alexios P. Polychronakos

Using arguments from two dimensional Yang-Mills theory and the collective coordinate formulation of the Calogero-Sutherland model, we conjecture the dynamical density correlation function for coupling $l$ and $1/l$, where $l$ is an integer. We present overwhelming evidence that the conjecture is indeed correct.

A. A. Tseytlin

Given a static string solution with some free constant parameters (`moduli&#39;) it may be possible to construct a time-dependent solution by just replacing the moduli by some functions of time. We present several examples when such `rolling moduli&#39; ansatz is consistent. In particular, the anisotropic D=4 cosmological solution of Nappi and Witten can be

D. Dicus, A. Stange, S. Willenbrock

Higgs bosons which decay principally to top quarks, such as in the minimal supersymmetric model, produce a peak-dip structure in the $gg\to t\bar t$ invariant-mass spectrum. This structure is potentially observable at the CERN Large Hadron Collider. (see BNL theory home page http://penguin.phy.bnl.gov/bnl.html for recent preprints)

M. Veltman

The validity of non-perturbative methods is questioned. The concept of relative space is introduced.

Sean M. Carroll, Edward Farhi, Alan H. Guth, Ken D. Olum

The discovery by Gott of a remarkably simple spacetime with closed timelike curves (CTC&#39;s) provides a tool for investigating how the creation of time machines is prevented in classical general relativity. The Gott spacetime contains two infinitely long, parallel cosmic strings, which can equivalently be viewed as point masses in (2+1)-dimensional gravity