April 1995 arXiv papers — page 10

Joseph Peter Morris

When using a formulation of Smooth Particle Hydrodynamics (SPH) which conserves momentum exactly the motion of the particles is observed to be unstable to negative stress. It is also found that under normal circumstances a lattice of SPH particles is potentially unstable to transverse waves. This document is a summary of a detailed report (Morris 1994) inves

Bruce Hunt

In this paper we consider a special class of arithmetic quotients of bounded symmetric domains which can roughly be described as higher- dimensional analogues of the Hilbert modular varities. The algebraic groups are defined as the unitary groups over two-dimensional right vector spaces over a division algebra with involution. If $d$ denotes the degree of th

Wei Chen, Jack Y. Ng, Hendrik van Dam

We propose a new fractional statistics for arbitrary dimensions, based on an extension of Pauli's exclusion principle, to allow for finite multi-occupancies of a single quantum state. By explicitly constructing the many-body Hilbert space, we obtain a new algebra of operators and a new thermodynamics. The new statistics is different from fractional exclu

E. Abdalla, M. C. B. Abdalla

Using the integrability conditions that we recently obtained in QCD$_2$ with massless fermions, we arrive at a sufficient number of conservation laws to be able to fix the scattering amplitudes involving a local version of the Wilson loop operator.

T. Csorgo, B. Lorstad

There are two length-scales present simultaneously in all the principal directions for three-dimensionally expanding, finite systems. These are discussed in detail for the case of a longitudinally expanding system with a transverse flow and a transverse temperature profile. For systems with large geometrical sizes we find an $m_t$-scaling for the parameters

Q. Daniel Wang

I report the detection of two X-ray sources of luminosities $\sim 10^{36} {\rm~ergs~s^{-1}}$ in the central region of 30 Doradus. These two sources appear point-like in images taken with the {\sl ROSAT} HRI. One of the sources is most likely associated with a close spectroscopic binary R140a2 (WN6) with an orbital period of 2.76 days. The mass of the unknown

K. Otmianowska-Mazur, M. Chiba

The evolution of large-scale magnetic fields in disk galaxies is investigated numerically. The gasdynamical simulations in a disk perturbed by spiral or bar potential are incorporated into the kinematic calculations of induction equations to elucidate the effects of non-axisymmetric disk structure on magnetic fields. The effects of interstellar turbulence ar

L. Diosi, K. Kulacsy, B. Lukacs, A. Rácz

In addition to the Riemannian metricization of the thermodynamic state space, local relaxation times offer a natural time scale, too. Generalizing existing proposals, we relate {\it thermodynamic} time scale to the standard kinetic coefficients of irreversible thermodynamics. Criteria for minimum entropy production in slow, slightly irreversible processes ar

P. Ball, M. Beneke, V. M. Braun

We present a determination of $|V_{cb}|$ from semileptonic B decays that includes resummation of supposedly large perturbative corrections, originating from the running of the strong coupling. We argue that the low value of the BLM scale found previously for inclusive decays is a manifestation of the renormalon divergence of the perturbative series starting

E. Comay

A charge-monopole theory is derived from simple and self-evident postulates. Charges and monopoles take an analogous theoretical structure. It is proved that charges interact with free waves emitted from monopoles but not with the corresponding velocity fields. Analogous relations hold for monopole equations of motion. The system's equations of motion ca

Simon Davis

The genus-dependence of multi-loop superstring amplitudes is bounded at large orders in perturbation theory using the super-Schottky group parametrization of supermoduli space. Partial estimates of supermoduli space integrals suggest an exponential dependence on the genus when the integration region is restricted to a single fundamental domain of the super-m

R. R. Zapatrin

The machinery is suggested to describe the varying spacetime topology on the level of its substitutes by finite topological spaces.

B. Kamal, Z. Merebashvili, A. P. Contogouris

Complete analytical results for the production of heavy-quark pairs by polarized and unpolarized photons in next-to-leading order are presented. Two-, three- and two plus three-jet cross sections for total photon spin $J_z=0,\pm 2$ are presented for $b\bar{b}(g)$ production. The 2-jet cross sections are considered as a background to $γγ\rightarrow H^* \right

P. Fendley, A. W. W. Ludwig, H. Saleur

We have recently calculated exact non-equilibrium quantum transport properties through a point contact in a Luttinger liquid. Using a particular quasiparticle basis of the Hilbert space dictated by integrability, we here compute explicitly the exact $I(V)$ characteristic and conductance out of equilibrium as a function of driving voltage $V$ and temperature

J. A. Tyson, P. Fischer

In this letter we present calibrated mass and light profiles of the rich cluster of galaxies Abell 1689 out to 1 $h^{-1}$ Mpc from the center. The high surface density of faint blue galaxies at high redshift, selected by their low surface brightness, are unique tools for mapping the projected mass distribution of foreground mass concentrations. The systemati

Inger Johanne Håland, Donald E. Knuth

Some identities are presented that generalize the formula x^3 = 3x floor(x floor(x)) - 3 floor(x) floor(x floor(x)) + floor(x)^3 + 3 frac(x) frac(x floor(x)) + frac(x)^3 to a representation of the product x_0x_1 ... x_{n-1}.

Donald E. Knuth

Given $n$ real numbers $0\leq x_1,...,x_n<1$ and a permutation~$σ$ of $\{1,...,n\}$, we can always find $\xbar_1,...,\xbar_n\in\{0,1\}$ so that the partial sums $\xbar_1+... +\xbar_k$ and $\xbar_{σ1}+... +\xbar_{σk}$ differ from the unrounded values $x_1+... + x_k$ and $x_{σ1}+... +x_{σk}$ by at most $n/(n+1)$, for $1\leq k\leq n$. The latter bound is best p

Joyce R. McLaughlin, Ole H. Hald

In this announcement we consider an eigenvalue problem which arises in the study of rectangular membranes. The mathematical model is an elliptic equation, in potential form, with Dirichlet boundary conditions. We have shown that the potential is uniquely determined, up to an additive constant, by a subset of the nodal lines of the eigenfunctions. A formula i

Juan J. Manfredi, Enrique Villamor

Let $F\in W^{1,n}_{\text{loc}}(Ω; \Bbb R^n)$ be a mapping with nonnegative Jacobian $J_F(x)=\det DF(x)\ge 0$ for a.e. $x$ in a domain $Ω\subset\Bbb R^n$. The {\it dilatation} of $F$ is defined (almost everywhere in $Ω$) by the formula $$K(x)=\frac{|DF(x)|^n}{J_F(x)}\cdot$$ Iwaniec and \v Sver\&#39; ak \ncite{IS} have conjectured that if $p\ge n-1$ and $K\in

Samuel S. Holland

Maria Pia Solèr has recently proved that an orthomodular form that has an infinite orthonormal sequence is real, complex, or quaternionic Hilbert space. This paper provides an exposition of her result, and describes its consequences for Baer $\ast$-rings, infinite-dimensional projective geometries, orthomodular lattices, and Mackey&#39;s quantum logic.

Armand Borel

This mostly expository paper centers on recently proved conjectures in two areas: A) A conjecture of A. Oppenheim on the values of real indefinite quadratic forms at integral points. B) Conjectures of Dani, Raghunathan, and Margulis on closures of orbits in spaces of lattices such as ${\BSL}_n(\R)/{\BSL}_n(\Z)$. At first sight, A) belongs to analytic number

René Schoof

In this expository paper we show how one can, in a uniform way, calculate the weight distributions of some well-known binary cyclic codes. The codes are related to certain families of curves, and the weight distributions are related to the distribution of the number of rational points on the curves.

Mikhail Lyubich, Michael Yampolsky

We extend Sullivan&#39;s complex a priori bounds to real quadratic polynomials with essentially bounded combinatorics. Combined with the previous results of the first author, this yields complex bounds for all real quadratics. Local connectivity of the corresponding Julia sets follows.

K. N. Ilinski, J. M. F. Gunn

We examine the notion of Haldane&#39;s dimension and the corresponding statistics in a probabilistic spirit. Motivated by the example of dimensional-regularization we define the dimension of a space as the trace of a diagonal `unit operator&#39;, where the diagonal matrix elements are not, in general, unity but are probabilities to place the system into a gi

Sergei Ketov, Olaf Lechtenfeld

The general structure of N=2 moduli space at arbitrary genus and instanton number is investigated. The N=2 NSR string measure is calculated, yielding picture- and U(1) ghost number-changing operator insertions. An explicit formula for the spectral flow operator acting on vertex operators is given, and its effect on N=2 string amplitudes is discussed.

H. Kleinert, J. Neu, V. Schulte-Frohlinde, K. G. Chetyrkin

Motivated by the discovery of errors in six of the 135 diagrams in the published five-loop expansions of the $β$-function and the anomalous dimensions of the ${O}(n)$-symmetric $ϕ^4$-theory in $D=4-\ep$ dimensions we present the results of a full analytic reevaluation of all diagrams. The divergences are removed by minimal subtraction and $\ep$-expansions ar

R. Caracciolo, A. Lerda, G. R. Zemba

We construct the effective field theory of the Calogero-Sutherland model in the thermodynamic limit of large number of particles $N$. It is given by a $\winf$ conformal field theory (with central charge $c=1$) that describes {\it exactly} the spatial density fluctuations arising from the low-energy excitations about the Fermi surface. Our approach does not r

Itzhak Bars

Witten proposed that the low energy physics of strongly coupled D=10 type-IIA superstring may be described by D=11 supergravity. To explore the stringy aspects of the underlying theory we examine the stringy massive states. We propose a systematic formula for identifying non-perturbative states in D=10 type-IIA superstring theory, such that, together with th

G. Valencia

I discuss the experimental signatures of a parity violating but CP conserving interaction in the symmetry breaking sector of the electroweak theory.

Marco Masetti, Francesca Sartogo

Perturbative cross section for direct B_c meson production in gluon gluon scattering g g --> B_c^+ b \bar{c} is calculated and compared with other existing results. Predictions for hadronic B_c production at Tevatron and LHC are presented and the main sources of uncertainties are discussed.

B. Ananthanarayan

We consider the possibility of violations of the selection rule $ΔS=ΔQ$ at an appreciable level in {\it exclusive} semi-leptonic decays of Kaons. At $Φ$-Factories, intense Kaon beams will be available and will probe among others, the semi-leptonic decays $K_{l4}$ and $K_{l3γ}$ in addition to $K_{l3}$ and could provide novel testing grounds for the $ΔS=ΔQ$ ru

M. Carena, S. Dimopoulos, S. Raby, C. E. M. Wagner

We reanalyse the problem of fermion masses in supersymmetric SO(10) grand unified models. In the minimal model, both low energy Higgs doublets belong to the same {\bf{10}} representation of SO(10) implying the unification not only of the gauge but also of the third generation Yukawa couplings. These models predict large values of $\tanβ\sim 50$. In this pape

ZEUS Collaboration

Deep inelastic $e^-p$ scattering has been studied in both the charged-current (CC) and neutral-current (NC) reactions at momentum transfers squared, $Q^2$, between 400 GeV$^2$ and the kinematic limit of 87500 GeV$^2$ using the ZEUS detector at the HERA $ep$ collider. The CC and NC total cross sections, the NC to CC cross section ratio, and the differential c

Carlo Rovelli

We study a tentative generally covariant quantum field theory, denoted the T-Theory, as a tool to investigate the consistency of quantum general relativity. The theory describes the gravitational field and a minimally coupled scalar field; it is based on the loop representation, and on a certain number of quantization choices. Four-dimensional diffeomorphism

E. W. M. Chow, A. W. -C. Lun

Vacuum asymptotically flat Robinson-Trautman spacetimes are a well known class of spacetimes exhibiting outgoing gravitational radiation. In this paper we describe a method of locating the past apparent horizon in these spacetimes, and discuss the properties of the horizon. We show that the past apparent horizon is non-timelike, and that its surface area is

S. K. Donoho, L. A. Rendell

Theory revision integrates inductive learning and background knowledge by combining training examples with a coarse domain theory to produce a more accurate theory. There are two challenges that theory revision and other theory-guided systems face. First, a representation language appropriate for the initial theory may be inappropriate for an improved theory

Yoshiki Niwa, Yoshihiko Nitta

A comparison was made of vectors derived by using ordinary co-occurrence statistics from large text corpora and of vectors derived by measuring the inter-word distances in dictionary definitions. The precision of word sense disambiguation by using co-occurrence vectors from the 1987 Wall Street Journal (20M total words) was higher than that by using distance

F. X. Timmes, S. E. Woosley, D. H. Hartmann, R. D. Hoffman

Using recently calculated yields for Type II supernovae, along with models for chemical evolution and the distribution of mass in the interstellar medium, the current abundances and spatial distributions of two key gamma-ray radioactivities, $^{26}$Al and $^{60}$Fe, are determined. The estimated steady state production rates are 2.0 $\pm$ 1.0 M\sun \ Myr$^{-