August 1996 arXiv papers — page 2

N. Evans, S. D. H. Hsu, A. Nyffeler, M. Schwetz

We use the chiral Lagrangian to investigate the global properties of the $N$-flavor QCD vacuum as a function of the $θ$ parameter. In the case of exact quark degeneracy we find evidence for first order phase transitions at $θ= π\cdot ({\rm odd~ integer})$. The first order transitions are smoothed by quark mass splittings, although interesting effects remain

D. Nanopoulos

After a quick tour through the present status of the Standard Model, an attempt is made to set up a framework to discuss some presently available exotica, including $R_b$ and the CDF $eeγγ+E_T\hskip-13pt/\ $ ``event." Supersymmetry seems to be a key player in establishing a paradigm shift beyond the Standard Model. (XI Topical Workshop on Proton-antiprot

John Ellis, Valery A. Khoze, W. J. Stirling

Hadronic antenna patterns provide a tool able to diagnose different patterns of colour flow in large-E_T jet events. They reflect the underlying short-distance dynamics, and are sensitive to colour coherence and interference between the initial- and final-state partons. We discuss how hadronic antenna patterns may be used on large-E_T events from the Fermila

Don Colladay, Alan Kostelecky

Parameters describing CPT violation are extracted from a variety of rate asymmetries in the neutral-$D$ system. The precision to which these parameters could be measured in present and planned machines is examined.

Savely G. Karshenboim

Radiative corrections to the Zemach contribution of the hydrogen hyperfine splitting are calculated. Their contributions amount to $-0.63(3)$ ppm to the HFS. The radiative recoil corrections are estimated to be $0.09(3)$ ppm and heavy particle vacuum polarization shifts the HFS by $0.10(2)$ ppm. The status of the nuclear-dependent contributions are considere

J. Blümlein, E. Boos, A. Kryukov

The scalar and vector leptoquark pair production cross sections for deep inelastic $ep$ scattering are calculated. Estimates are presented for the search potential at HERA.

Graham Boyd, David E. Miller

An analysis of the temperature dependence of the leading contributions to the gluon condensate for SU(N) lattice gauge theory is presented using the data from recent Monte Carlo simulations. The gluon condensate is calculated directly from the new lattice calculations of the interaction measure. It is shown how these computations provide a simple picture for

J. M. Butterworth, L. Feld, M. Klasen, G. Kramer

Predictions from a new next-to-leading order (NLO) calculation for direct and resolved photoproduction of one and two jets are compared to simulated HERA data. We propose a method to match experimental and theoretical jet definitions and observe a reduced dependence on jet definitions and hadronization corrections at larger transverse energies. From the irre

K. G. Chetyrkin

By a completely independent analytic calculation made in general covariant gauge we confirm the known result for the massless $α_s^3$ correction to $R_{had}$ and check explicitly its gauge independence. We extend the calculations to include contributions due to a hypothetical existence of a colour octet of (light) neutral fermions known also under the name o

S. Hegyi

On the basis of a recently introduced generalization of the negative binomial distribution the influence of higher-order perturbative QCD effects on multiplicity fluctuations are studied for deep inelastic e^+p scattering at HERA energies. It is found that the multiplicity distributions measured by the H1 Collaboration indicate violation of infinite divisibi

G. C. Branco, D. Emmanuel-Costa, J. I. Silva-Marcos

We do a systematic analysis of the question of calculability of CKM matrix elements in terms of quark mass ratios, within the framework of the hypothesis of universality of strength for Yukawa couplings (USY), where all Yukawa couplings have equal moduli, and the flavor dependence is only in their phases. We use the fact that the limit $m_u=m_d=0$ is special

Christian Holm, Wolfhard Janke

We study 2D quantum gravity on spherical topologies using the Regge calculus approach with the $dl/l$ measure. Instead of a fixed non-regular triangulation which has been used before, we study for each system size four different random triangulations, which are obtained according to the standard Voronoi-Delaunay procedure. We compare both approaches quantita

JLQCD Collaboration, S. Aoki, M. Fukugita, S. Hashimoto

We propose a non-perturbative method to determine the mixing coefficients of $Δs=2$ four-quark operators for the Wilson quark action using chiral Ward identities. The method is applied to calculate B_K in quenched QCD.

Y. Iwasaki

The CP-PACS computer with a peak speed of 300 Gflops was completed in March 1996 and has started to operate. We describe the final specification and the hardware implementation of the CP-PACS computer, and its performance for QCD codes. A plan of the grade-up of the computer scheduled for fall of 1996 is also given.

S. Teige

The mass and width of the a0(980) have been independently determined from a nearly background free data sample and the coupling constants to the eta-pi and K-K-bar modes have been determined

Siegfried Echterhoff, S. Kaliszewski, Iain Raeburn

Mansfield showed how to induce representations of crossed products of C*-algebras by coactions from crossed products by quotient groups and proved an imprimitivity theorem characterising these induced representations. We give an alternative construction of his bimodule in the case of dual coactions, based on the symmetric imprimitivity theorem of the third a

Tom Chou, Marko V. Jaric', Eric D. Siggia

The electrostatic contribution to spontaneous membrane curvature is calculated within Poisson-Boltzmann theory under a variety of assumptions and emphasizing parameters in the physiological range. Asymmetric surface charges, either fixed with respect to bilayer midplane area, or with respect to the lipid-water area both induce curvature but of opposite sign.

Claudio Furtado, Fernando Moraes

Using a continuum model, we obtain qualitative results that imply charge localization around negative curvature disclinations (i.e. rings with more than 6 Carbon atoms) in a graphite sheet. Conversely, it is found that positive curvature disclinations repel charge, independent of its sign.

Angelo Cacciuto, Enzo Marinari, Giorgio Parisi

We use a constrained Monte Carlo technique to analyze ultrametric features of a 4 dimensional Edwards-Anderson spin glass with quenched couplings J=\pm 1. We find that in the large volume limit an ultrametric structure emerges quite clearly in the overlap of typical equilibrium configurations.

Meng-she Cao, E. G. D. Cohen

The scaling behavior of the closed trajectories of a moving particle generated by randomly placed rotators or mirrors on a square or triangular lattice in the critical region are investigated. We study numerically two scaling functions: $f(x)$ related to the trajectory length distribution $n_S$ and $h(x)$ related to the trajectory size $R_S$ (gyration radius

Meng-she Cao, E. G. D. Cohen

The scaling behavior of the closed trajectories of a moving particle generated by randomly placed rotators or mirrors on a square or triangular lattice is studied numerically. For most concentrations of the scatterers the trajectories close exponentially fast. For special critical concentrations infinitely extended trajectories can occur which exhibit a scal

Jian Wang, Hong Guo

The frequency dependent conductance of a two-dimensional quantum wire is computed using a current conserving formalism. The correction to the dc-conductance due to a time-dependent potential is related to the local partial density of states which we compute numerically. The current conservation is explicitly confirmed by computing the global density of state

U. S. Schwarz, K. Swamy, G. Gompper

We study the dependence of the phase behavior of ternary amphiphilic systems on composition and temperature. Our analysis is based on a curvature elastic model of the surfactant film with sufficiently large spontaneous curvature and sufficiently negative saddle-splay modulus that the stable phases are the lamellar phase and a droplet microemulsion. In additi

S. Mertens, A. Engel

We investigate the VC-dimension of the perceptron and simple two-layer networks like the committee- and the parity-machine with weights restricted to values $\pm1$. For binary inputs, the VC-dimension is determined by atypical pattern sets, i.e. it cannot be found by replica analysis or numerical Monte Carlo sampling. For small systems, exhaustive enumeratio

T. Christen, M. Buttiker

While the static capacitance matrix is always symmetric and thus an even function of the magnetic field, the dynamic capacitance matrix of multi-terminal samples obeys in general only the weaker Onsager-Casimir symmetry relations. Our results are in accordance with recent experimental observations of asymmetric dynamic capacitances in quantized Hall systems.

Thierry Giamarchi, Pierre Le Doussal

It was shown in our Letter that the novel glassy property of the moving lattice (transverse critical force and pinned channels) originate {\it only} from the periodicity in the {\it transverse} direction, i.e the underlying smectic density modes of the structure. Thus, contrarily to the claim of the Comment, these properties should be robust to the details o

H. T. C. Stoof

We present the quantum theory for the nucleation of Bose-Einstein condensation in a dilute atomic Bose gas. This quantum theory comfirms the results of the semiclassical treatment, but has the important advantage that both the kinetic and coherent stages of the nucleation process can now be described in a unified way by a single Fokker-Planck equation.

R. Hilfer, T. Rag, B. Virgi

Local percolation probabilities are used to characterize the connectivity in porous and heterogeneous media. Together with local porosity distributions they allow to predict transport properties \cite{hil91d}. While local porosity distributions are readily obtained, measurements of the local percolation probabilities are more difficult and have not been atte

M. Weigt, R. Monasson

We analyse the eigenvalue structure of the replicated transfer matrix of one-dimensional disordered Ising models. In the limit of $n \rightarrow 0$ replicas, an infinite sequence of transfer matrices is found, each corresponding to a different irreducible representation (labelled by a positive integer $ρ$) of the permutation group. We show that the free ener

M. Batsch, L. Schweitzer

The statistical properties of energy eigenvalues in the critical regime of the lowest Landau band are investigated. The nearest neighbour level spacing distribution $P(s)$ and the Mehta quantity $I_0$, from which the scaling exponent $ν$ of the correlation length can be derived, are calculated. While $P(s)$ disagrees with recent analytical predictions, $ν$ i

Steven H. Simon

The Fermionic Chern-Simons approach has had remarkable success in the description of quantum Hall states at even denominator filling fractions $ν=\frac{1}{2m}$. In this paper we review a number of recent works concerned with modeling this state as a Landau-Silin Fermi liquid. We will then focus on one particular problem with constructing such a Landau theory

Patrick Juola

Although the confusion of individual phonemes and features have been studied and analyzed since (Miller and Nicely, 1955), there has been little work done on extending this to a predictive theory of word-level confusions. The PGPfone alphabet is a good touchstone problem for developing such word-level confusion metrics. This paper presents some difficulties

Patrick Juola

Phonetic ambiguity and confusibility are bugbears for any form of bottom-up or data-driven approach to language processing. The question of when an input is ``close enough'' to a target word pervades the entire problem spaces of speech recognition, synthesis, language acquisition, speech compression, and language representation, but the variety of re

Eric M. Visser, Masaru Fuji

This paper elaborates on the design of a machine translation evaluation method that aims to determine to what degree the meaning of an original text is preserved in translation, without looking into the grammatical correctness of its constituent sentences. The basic idea is to have a human evaluator take the sentences of the translated text and, for each of

J. W. Moffat

A covariant Lagrangian formulation of a solution to the cosmological constant problem, based on vizualising the fluctuations of the vacuum energy as a non-equilibrium process with stochastic behaviour, is presented. The variational principle yields equations of motion for the cosmological ``constant" $Λ$, treated as a dynamical field, together with an eq

F. Halzen, T. Stanev, G. B. Yodh

Although gamma ray showers are muon-poor, they still produce a number of muons sufficient to make the sources observed by GeV and TeV telescopes observable also in muons. For sources with hard gamma ray spectra there is a relative `enhancement' of muons from gamma ray primaries as compared to that from nucleon primaries. All shower gamma rays above the p

C. A. Scharf, L. R. Jones, H. Ebeling, E. Perlman

We have embarked on a survey of ROSAT PSPC archival data with the aim of detecting all significant surface brightness enhancements due to sources in the innermost 15 arcmin of the PSPC field of view (0.5-2.0 keV). This project is part of the Wide Angle ROSAT Pointed Survey (WARPS) and is designed primarily to measure the low luminosity, high redshift, X-ray

Greg Schwarz, Peter H. Hauschildt, Sumner Starrfield, Eddie Baron

We have analyzed the early optically thick ultraviolet spectra of Nova OS And 1986 using a grid of spherically symmetric, non-LTE, line-blanketed, expanding model atmospheres and synthetic spectra with the following set of parameters: $5,000\le$ T$_{model}$ $\le 60,000$K, solar abundances, $ρ\propto r^{-3}$, $\v_{max} = 2000\kms$, $L=6 \times 10^{4}\Lsun$, a

W. Zheng, G. A. Kriss, R. C. Telfer, J. P. Grimes

We construct a composite quasar spectrum from 284 HST FOS spectra of 101 quasars with redshifts z > 0.33. The spectrum covers the wavelengths between 350 and 3000 A in the rest frame. There is a significant steepening of the continuum slope around 1050 A. The continuum between 1050 and 2200 A can be modeled as a power law with alpha = -0.99. For the full sam

Hans J. Witt

We show here that quadruple lenses can be useful laboratories to probe whether the potential of the lensing galaxy is purely elliptical or whether an additional distortion is present in the deflector plane. For this test we only have to know the relative image positions of the quadruple lens system and the (relative) center of light position of the lensing g

Martin J. Rees

This paper considers how the first subgalactic structures produced the UV radiation that ionized the intergalactic medium before $z = 5$, and the `feedback' effects of the UV radiation on structure formation. The relevance of pregalactic activity to heavy element production and the origin of magnetic fields is briefly addressed.

Shai Kaspi, Paul S. Smith, Dan Maoz, Hagai Netzer

We present 4 years of spectrophotometric monitoring data for two radio-quiet quasars, PG 0804+762 and PG 0953+414, with typical sampling intervals of several months. Both sources show continuum and emission line variations. The variations of the H$β$ line follow those of the continuum with a time lag, as derived from a cross-correlation analysis, of 93$\pm$3

Tal Alexander, Hagai Netzer

The Bloated Stars Scenario proposes that AGN broad line emission originates in the winds or envelopes of bloated stars (BS). Alexander and Netzer (1994) established that ~ 5e4 BSs with dense, decelerating winds can reproduce the observed emission line spectrum and avoid rapid collisional destruction. Here, we use the observed properties of AGN line profiles

M. Maisack, K. Mannheim, W. Collmar

Seyfert galaxies have not been detected by COMPTEL on the Compton Gamma Ray Observatory (CGRO) in the energy range 0.75-3 MeV, placing upper limits on their emission which are more than an order of magnitude below previously reported detections. Here, we extend our previous work to the energy range 3-30 MeV. Again, we find no evidence for emission from a cum

S. Perlmutter, S. Gabi, G. Goldhaber, D. E. Groom

We have developed a technique to systematically discover and study high-redshift supernovae that can be used to measure the cosmological parameters. We report here results based on the initial seven of >28 supernovae discovered to date in the high-redshift supernova search of the Supernova Cosmology Project. We find a dispersion in peak magnitudes of sigma_{

Meng-Kiat Chuah

Let K be a compact semi-simple Lie group. We classify K-invariant Kaehler structures on the space Kc/(P,P), where Kc is the complexification of K, P is a parabolic subgroup of Kc, and (P,P) the commutator subgroup. For each Kaehler structure, we study its moment map and associated pre-quantum line bundle for geometric quantization. Some holomorphic sections

David V. Bowen, Eline Tolstoy, Andrea Ferrara, J. Chris Blades

We have obtained spectra of three QSO/AGNs with the GHRS aboard the Hubble Space Telescope to search for absorption from low column density gas in the halo of the dwarf spheroidal (dSph) galaxy Leo I. The probe sightlines pass 2.1, 3.7, and 8.1 kpc from the center of the galaxy, but no CIV, SiII, or SiIV absorption is found at the velocity of Leo I. The abse

U. Pustogowa, W. Huebner, K. H. Bennemann

We calculate the linear magneto-optical Kerr rotation angle for CeSb in the near-infrared spectral range. Using an exact formula for large Kerr rotation angles and a simplified electronic structure of CeSb we find at $\hbar ω= 0.46 eV$ a Kerr rotation of 90 degrees which then for decreasing $ω$ jumps to -90 degrees in very good agreement with recent experime

J. Blümlein, S. Riemersma, A. Vogt

A survey is given of recent developments on the resummed small-$x$ evolution, in a framework based on the renormalization group equation, of non--singlet and singlet structure functions in both unpolarized and polarized deep--inelastic scattering. The available resummed anomalous dimensions are discussed for all these cases, and the most important analytic a

Oliver Rudolph

The basic ingredients of the consistent histories approach to quantum mechanics are the space of histories and the space of decoherence functionals. In this work we extend the classification theorem for decoherence functionals proven by Isham, Linden and Schreckenberg to the case where the space of histories is the lattice of projection operators on an arbit

M. Kachelriess, G. Wunner

withdrawn - wrong selection rules used.

Petrus Pennanen

A continuum extrapolation of static two- and four-quark energies calculated in quenched SU(2) lattice Monte Carlo is carried out based on Sommer's method of setting the scale. The beta-function is obtained as a side product of the extrapolations. Four-quark binding energies are found to be essentially constant at beta >= 2.35 unlike the two-body potentials.

T. A. Porter, R. J. Protheroe

The bulk of the diffuse galactic gamma-ray emission above a few tens of GeV has been conventionally ascribed to the decay of neutral pions produced in cosmic-ray interactions with interstellar matter. Cosmic-ray electrons may, however, make a significant contribution to the gamma-ray spectrum at high energies, and even dominate at TeV-PeV energies depending

JLQCD Collaboration, S. Aoki, M. Fukugita, S. Hashimoto

Several topics concerning the light hadron spectrum are discussed. Flavor symmetry breaking effects and the problem of quenched chiral logarithm are examined with pion mass data for the Kogut-Susskind quark action, and light meson decay constants for the Wilson action calculated with non-perturbative renormalization constants are discussed. Results for quark

Gerald Hoehn

The shadow V' of a self-dual vertex operator superalgebra V is defined as the direct sum of the irreducible modules of its even vertex operator subalgebra $V_{(0)}$ not contained in $V=V_{(0)}+V_{(1)}$. We describe the self-dual ``very nice'' unitary rational vertex operator superalgebras V of rank c whose shadows have the largest possible minima

S. B. Isakov, G. S. Canright, M. D. Johnson

We discuss exclusion statistics parameters for quasiholes and quasielectrons excited above the fractional quantum Hall states near $ν=p/(2np+1)$. We derive the diagonal statistics parameters from the (``unprojected'') composite fermion (CF) picture. We propose values for the off-diagonal (mutual) statistics parameters as a simple modification of thos

H. David Politzer

The angle and temperature dependence of the photon scattering rate for Bose-stimulated atom recoil transitions between occupied states is compared to diffraction and incoherent Rayleigh scattering near the Bose-Einstein transition for an optically thin trap in the limit of large particle number, N. Each of these processes has a range of angles and temperatur

Frank Antonsen, Karsten Bormann

It has been proposed that wormholes can be made to function as time-machines. This opens up the question of whether this can be accomodated within a self-consistent physics or not. In this contribution we present some quantum mechanical considerations in this respect.

Frank Antonsen

We first introduce the Wigner-Weyl-Moyal formalism for a theory whose phase-space is an arbitrary Lie algebra. We also generalize to quantum Lie algebras and to supersymmetric theories. It turns out that the non-commutativity leads to a deformation of the classical phase-space: instead of being a vector space it becomes a manifold, the topology of which is g

Tchavdar D. Palev, Preeti Parashar

An alternative to the Chevalley description of Lie algebra sl(n+1), of its universal enveloping algebra U[sl(n+1)] and of its q-deformed analogue U_q[sl(n+1)] in terms of generators, called creation and annihilation generators (CAGs), and relations is given. It is indicated (without further discussions) that the representations of the CAGs describe new quant

Xiao-jun Li, Hao-wen Xi, J. D. Gunton

Explicit formulas for the rotation frequency and the long-wavenumber diffusion coefficients of global spirals with $m$ arms in Rayleigh-Benard convection are obtained. Global spirals and parallel rolls share exactly the same Eckhaus, zigzag and skewed-varicose instability boundaries. Global spirals seem not to have a characteristic frequency $ω_m$ or a typic

D. Drechsel, G. Knoechlein, A. Metz, S. Scherer

We discuss the low-energy behavior of the spin-averaged amplitude of virtual Compton scattering (VCS) off a nucleon. Based on gauge invariance, Lorentz invariance and the discrete symmetries, it is shown that to first order in the frequency of the final real photon only two generalized polarizabilities appear. Different low-energy expansion schemes are discu

Koichi Saito, Kazuo Tsushima, Anthony W. Thomas

Using a self-consistent, Hartree description for both infinite nuclear matter and finite nuclei based on a relativistic quark model (the quark-meson coupling model), we investigate the variation of the masses of the non-strange vector mesons, the hyperons and the nucleon in infinite nuclear matter and in finite nuclei.

L. Frankfurt, T-S. H. Lee, G. A. Miller, M. Strikman

Color transparency is the vanishing of initial and final state interactions, predicted by QCD to occur in high momentum transfer quasielastic nuclear reactions. For specific reactions involving nucleons, the initial and final state interactions are expected to be dominated by exchanges of pions. We argue that these interactions are also suppressed in high mo

G. Mikhalkin

The zero set of a real polynomial in two variable is a curve in $\mathbb R^2$. For a generic choice of its coefficients this is a non-singular curve, a collection of circles and lines properly embedded in $\mathbb R^2$. What topological arrangements of these circles and lines appear for the polynomials of a given degree? This question arised in the 19th cent

Nelson R. F. Braga, Clovis Wotzasek

We study the non-abelian extension for the splitting of a scalar field into chiral components. Using this procedure we find a non ambiguous way of coupling a non abelian chiral scalar field to gravity. We start with a (non-chiral) WZW model covariantly coupled to a background metric and, after the splitting, arrive at two chiral Wess-Zumino-Witten (WZW) mode

A. Johansen

We study some aspects of enhanced gauge symmetries in F-theory compactified on K3. We find open string configurations connecting various 7-branes which represent stable BPS states. In this approach we recover $D_n$ and $E_n$ gauge groups previously found from an analysis of sigularities of the moduli space of elliptically fibered K3 manifolds as well as exam

Kimyeong Lee

We review a progress in our understanding of the moduli space for an arbitrary number of BPS monopoles in a gauge theory with a group $G$ of rank $r$ that is maximally broken to $U(1)^r$. The derivation of the moduli space metric has been obtained from studying the low energy dynamics of well-separated dyons.

Yuri M. Malyuta, Nikolay N. Aksenov

It is shown that the model X_{14}(7,3,2,1,1) has two Calabi--Yau phases.

W. Lerche, N. P. Warner

We show that the genus 34 Seiberg-Witten curve underlying $N=2$ Yang-Mills theory with gauge group $E_6$ yields physically equivalent results to the manifold obtained by fibration of the $E_6$ ALE singularity. This reconciles a puzzle raised by $N=2$ string duality.

T. Padmanabhan

The action for a relativistic free particle of mass $m$ receives a contribution $-mds$ from a path segment of infinitesimal length $ds$. Using this action in a path integral, one can obtain the Feynman propagator for a spinless particle of mass $m$. If one of the effects of quantizing gravity is to introduce a minimum length scale $L_P$ in the spacetime, the

A. Widom, Y. N. Srivastava

The theory of neutrino flavor rotations is discussed in terms of wave function solutions to the Dirac equation with a neutrino mass matrix. We give a critical review of the nature of neutrino oscillations.

M. Svec

Recently several experimental groups analysed data on $π^- p \to ηπ^- p$ and $π^- p \to ηπ^0 n$ reactions with exotic $1^{-+}$ $P$-wave and found a conflicting evidence for an exotic meson $I=1 1^{-+} (1405)$. High statistics data on these reactions are presently analysed by BNL E852 Collaboration. All these analyses are based on the crucial assumption that

S. Matinyan

The investigations of the gauge boson wave packets collisions in SU(2) Higgs model are presented. The evolution of the gauge and Higgs fields is studied as a function of the amplitude and the mass ratio of $M_H/M_W$. We visualize the restoration of spontaneously broken gauge symmetry during collisions.

Harry G. Blundell

This thesis examines three problems of the quark model, split between two general areas. The general areas are: 1) models of meson decay ($^3P_0$ and flux-tube breaking), 2) final state interactions (FSI's). The three specific problems are: 1) identification of the $f_4(2220)$ state, 2) determination of the mixing angle between the $K_1(1270)$ and $K_1(1

W. Porod, T. Wöhrmann

Within the Minimal Supersymmetric Standard Model we study the three body decay of the lighter top squark into a b-quark, a W-boson and the lightest neutralino and compare this decay with the flavour changing two body decay of the lighter top squark into a c-quark and the lightest neutralino. We do this for scenarios where two body decays at tree level are fo

R. Alkofer, A. Hauck, L. von Smekal

Using Mandelstam's approximation to the gluon Dyson-Schwinger equation we calculate the gluon self-energy in a renormalisation group invariant fashion. We obtain a non-perturbative $β$ function. The scaling behaviour near the ultraviolet stable fixed point is in good agreement with perturbative QCD. No further fixed point for positive values of the coupl

T. Gehrmann

Longitudinal polarization of the HERA electron beam allows the study of spatial asymmetries in the final state of single inclusive hadron production in $\vec{e}p$-collisions. We estimate the size of a particular production asymmetry which is related to the time reversal properties of the underlying parton level subprocess.

T. Gehrmann, W. J. Stirling

The production of Drell-Yan pairs in the double polarized mode of HERA-$\vec{\rm N}$ is studied at next-to-leading order in QCD. It is found that a measurement of this observable could yield vital information on the polarization of the light quark sea in the nucleon.

Minos Axenides, Andrei Johansen, Holger Bech Nielsen

We demonstrate that the number of fermionic zero modes of the static $2$-dimensional Dirac operator in the background of $SU(2)$ static gauge-Higgs field configurations is a topological invariant modulo four. Static configurations which are everywhere odd under parity with even-parity pure gauge behaviour at infinity admit $4n$, $n\in {\bf Z},$ zero modes of

C. Q. Geng, C. P. Kao

We investigate the longitudinal lepton polarization asymmetry in the exclusive processes $B\to K l^+l^-$ and $B\to K^* l^+l^-$. We include both short and long-distance contributions to the asymmetry in our discussions. We find that average values of the polarization asymmetries of the muon and tau for $B\to K^{(*)}μ^+μ^-$ and $B\to K^{(*)}τ^+τ^-$ are $-0.8\

Nils Tornqvist

The available data on the a0(980), f0(980), f0(1300) and K*0(1430) mesons are fitted as a distorted 0++ nonet using only 6 parameters and a very general model. This includes all light two-pseudoscalar thresholds, constraints from Adler zeroes, flavour symmetric couplings, unitarity and physically acceptable analyticity. One finds that with the large overall

W. -D. Nowak, A. V. Sidorov, M. V. Tokarev

We investigate the possibility to draw conclusions on the sign of the spin-dependent gluon distribution, $ΔG(x, Q^2)$, from existing polarized DIS data. The spin-dependent parton distributions $Δu_v, Δd_v, Δ{\bar u}, Δ{\bar d}, Δ{s}$, and $ΔG$ are constructed in the framework of a phenomenological procedure taking into account some assumptions on signs of va

Savely G. Karshenboim

A specific combination of $s$-state Lamb shift $ΔE_L(1s_{1/2}) - n^3 ΔE_L(ns_{1/2})$ is considered. Its value is calculated both in the hydrogen and deuterium atoms for $n$ up to 12. The result inludes all correction which can contribute $1 kHz$ and particulary: one-loop self energy and vacuum polarization, two-loop contribution. Nuclear finite-size correcti

A. V. Sidorov, M. V. Tokarev

The $x$- and $Q^2$-dependences of the Gottfried sum rule $S_G(x,Q^2)$ based on the experimental data on proton and deuteron structure functions are studied. The dependence of $S_G(x,Q^2)$ on $Q^2$ for low $x$ points to flavour asymmetry of sea quark distributions. For the first time, the coefficients $c_1, c_2$ of the expansion of $S_G(x,Q^2)$ in $α_S/π$ up

Chong Sheng Li, Robert J. Oakes, Jin Min Yang

We calculate Yukawa corrections of order $α_{ew} M_t^2/M_W^2$ to single top quark production via $q \bar q'\rightarrow t \bar b$ at the Fermilab Tevatron in the two-Higgs-doublet models. In our calculation we also keep the terms proportional to $ M_b^2 \tan^2 β$ since their effects may become rather important for large $\tanβ$. The corrections can amount

A. Yu. Umnikov, F. C. Khanna, L. P. Kaptari

We present a systematic study of the leading twist structure functions of the deuteron, F_2^D, b_{1,2}^D and g_1^D in a fully relativistic approach. Our study is based on a realistic Bethe-Salpeter amplitude for the deuteron, which is obtained as a solution to the homogeneous Bethe-Salpeter equation with a realistic NN kernel. Particular effort is made to co

Jeroen Snippe

We present the one-loop coefficients for an alternative Symanzik improved lattice action with gauge groups SU(2) or SU(3).

Alan C. Irving, James C. Sexton

We describe a systematic approach to generating approximate actions for the lattice simulation of QCD. Three different tuning conditions are defined to match approximate with true actions, and it is shown that these three conditions become equivalent when the approximate and true actions are sufficiently close. We present a detailed study of approximate acti

K. Abe

We have measured the distributions of the jet energies in e+e- --> qq^bar g events, and of the three orientation angles of the event plane, using hadronic $Z^0$ decays collected in the SLD experiment at SLAC. We find that the data are well described by perturbative QCD incorporating vector gluons. We have also compared our data with models of scalar and tens

Valerio Faraoni

Recent theoretical work determines the correct coupling constant of a scalar field to the Ricci curvature of spacetime in general relativity. The periodicity in the redshift distribution of galaxies observed by Broadhurst {\em et al.}, if genuine, determines the coupling constant in the proposed scalar field models. As a result, these observations contain im

V. A. Rubakov, O. Yu. Shvedov

The problem of topology change transitions in quantum gravity is discussed. We argue that the contribution of the Giddings-Strominger wormhole to the Euclidean path integral is pure imaginary. This is checked by two techniques: by the functional integral approach and by the analysis of the Wheeler-De Witt equation. We present also a simple quantum mechanical

John Baker, Andrew Abrahams, Peter Anninos, Steve Brandt

We study the radiation from a collision of black holes with equal and opposite linear momenta. Results are presented from a full numerical relativity treatment and are compared with the results from a ``close-slow'' approximation. The agreement is remarkable, and suggests several insights about the generation of gravitational radiation in black hole

Eugene Lerman

We study the stability of symmetric trajectories of a particle on the Lie group $SO(3)$ whose motion is governed by an $SO(3)\times SO(2)$ invariant metric and an $SO(2)\times SO(2)$ invariant potential. Our method is to reduce the number of degrees of freedom at {\em singular} values of the $SO(2)\times SO(2)$ momentum map and study the stability of the equ

Wolfram Kramer

A universal lower bound for the first positive eigenvalue of the Dirac operator on a compact quaternionic Kaehler manifold M of positive scalar curvature is calculated. It is shown that it is equal to the first positive eigenvalue on the quaternionic projective space. For this, the horizontal tangent bundle on the canonical SO(3)-bundle over M is equipped wi

C. L. Kane, E. J. Mele

A theory of the long wavelength low energy electronic structure of graphite-derived nanotubules is presented. The propagating $π$ electrons are described by wrapping a massless two dimensional Dirac Hamiltonian onto a curved surface. The effects of the tubule size, shape and symmetry are included through an effective vector potential which we derive for this

S. Krompiewski, U. Krey

Oscillations of the giant magnetoresistance (GMR) and thermo-electric power (TEP) vs. both the thickness of the non-magnetic spacer and also that of the ferromagnetic slabs are studied in the current-perpendicular-to-plane (CPP) geometry of magnetic trilayer systems, in terms of a single-band tight-binding model without impurities. The spin-dependent conduct

Daniel Alonso, Sudhir R. Jain

Motivated by numerical experiments and studies of quantum systems which are classically chaotic, we take a Random Matrix description of a Hard-sphere gas to Statistical Mechanical description. We apply this to Anyon gas and obtain a formal expression for the momentum distribution. Various limiting situations are discussed and are found in agreement with the

Sergio Conti, Giovanni Vignale

We present a microscopic theory of the collective modes of a ``smooth'' edge of a quantum Hall system, showing under what conditions these modes can be described as a set of independent bosons. We then calculate the electronic spectral function in an independent-boson model - a procedure that reduces to standard bosonization in the limit of ``sharp&#

M. B. Walker, J. Luettmer-Strathmann

A macroscopic symmetry group describing the superconducting state of an orthorhombically twinned crystal of YBCO is introduced. This macroscopic symmetry group is different for different symmetries of twin boundaries. Josephson tunneling experiments performed on twinned crystals of YBCO determine this macroscopic symmetry group and hence determine the twin b