February 1999 arXiv papers — page 11

Yi-Bing Ding, Xue-Qian Li, Peng-Nian Shen

In this work, we carefully study the energy eigen-values and splitting of heavy quarkonia as there exist $1/r^3$ and $\delta^3(\vec r)$ singular terms in the potential which make a direct numerical solution of the Schr\"{o}dinger equation impossible. We compare the results obtained in terms of perturbation and variational methods with various treatments.

K. Ogawa, H. Nakada, S. Hino, R. Motegi

The asymmetry in the energy spectra between mirror nuclei (the Thomas-Ehrman shifts) around $^{16}$O is investigated from a phenomenological viewpoint. The recent data on proton-rich nuclei indicates that the residual nuclear interaction is reduced for the loosely bound s-orbit by as much as 30%, which originates in the broad radial distribution of the proto

Abraham Loeb, George Rybicki

The spectra of the first galaxies and quasars in the Universe should be strongly absorbed shortward of their rest-frame Lyman-alpha wavelength by neutral hydrogen (HI) in the intervening intergalactic medium. However, the Lyman-alpha line photons emitted by these sources are not eliminated but rather scatter until they redshift out of resonance and escape du

J. S. Bloom, S. C. Odewahn, S. G. Djorgovski, S. R. Kulkarni F. A. Harrison

We present deep images of the field of gamma-ray burst (GRB) 990123 obtained in a broad-band UV/visible bandpass with the Hubble Space Telescope, and deep near-infrared images obtained with the Keck-I 10-m telescope. Both the HST and Keck images show that the optical transient (OT) is clearly offset by 0.6 arcsec from an extended object, presumably the host

M. Baake, U. Grimm, R. J. Baxter

A zero-field Ising model with ferromagnetic coupling constants on the so-called Labyrinth tiling is investigated. Alternatively, this can be regarded as an Ising model on a square lattice with a quasi-periodic distribution of up to eight different coupling constants. The duality transformation on this tiling is considered and the self-dual couplings are dete

Christof Zalka

We want to find a marked element out of a black box containing N elements. When the number of marked elements is known this can be done elegantly with Grover's algorithm, a variant of which even gives a correct result with certainty. On the other hand, when the number of marked elements is not known the problem becomes more difficult. For every prescribe

Tom Ostoma, Mike Trushyk

On a new approach to quantum gravity called Electro-Magnetic Quantum Gravity (EMQG) which is manifestly compatible with Cellular Automata (CA) theory and is based on a new theory of inertia (ref. 5) proposed by R. Haisch, A. Rueda, and H. Puthoff (which we modified and called Quantum Inertia). Newtonian Inertia is due to the strictly local electrical force i

Tom Ostoma, Mike Trushyk

A new formulation of special relativity is described. It is based on a postulate that the universe is a vast Cellular Automata (CA). We show that any CA model automatically leads to a maximum speed limit for the transfer of information from place to place in CA space, and hence leads to strict physical locality of all physical interactions. Furthermore, we s

M. Yu. Kuchiev, V. N. Ostrovsky

Fully quantum treatment explicitly presents the high harmonic generation as a three-stage process: above threshold ionization (ATI) is followed by the continuum electron propagation in a laser field and subsequent stimulated recombination back into the initial state. The contributions of all ATI channels add up coherently. All three stages of the process are

G. F. Gribakin, V. K. Ivanov, A. V. Korol, M. Yu. Kuchiev

Two-photon detachment from the F-minus negative ion is investigated within the lowest order of perturbation theory. We show that in accordance with the adiabatic theory a proper asymptotic behaviour of the 2p bound state wave function is crucial for obtaining correct absolute values of the multiphoton detachment cross sections. We find that the latter are su

Hungchong Kim, Su Houng Lee, Makoto Oka

We construct three different sum rules from the two-point correlation function with pion, $i\int d^4x e^{iq\cdot x} <0| T J_N(x) {\bar J}_N(0)|π(p)>$, beyond the soft-pion limit. The PS and PV coupling schemes in the construction of the phenomenological side are carefully considered in each sum rule. We discuss the dependence of the result on the specific Di

M. D&#39;Agostino, A. S. Botvina, M. Bruno, A. Bonasera

The distribution of fragments produced in events involving the multifragmentation of excited sources is studied for peripheral Au + Au reactions at 35 A.MeV. The Quasi-Projectile has been reconstructed from its de-excitation products. An isotropic emission in its rest frame has been observed, indicating that an equilibrated system has been formed. The excita

D. Pelte

From the pion production rates n_{pi} / A_{part} and the pion charge ratios R_{pi} = n_{pi^-} / n_{pi^+} and S_{pi} = n_{pi^0} / (n_{pi^-} + n_{pi^+}), measured in p + A and A + A reactions, it is concluded that the mass of the Delta(1232) resonance is reduced in dense nuclear matter. This conclusion is supported by the Delta(1232) mass distribution extracte

Peter Schupp

Lieb&#39;s conjecture for the Wehrl entropy of Bloch coherent states is proved for spin 1 and spin 3/2. Using a geometric representation we solve the entropy integrals for states of arbitrary spin and evaluate them explicitly in the cases of spin 1, 3/2, and 2. We also give a group theoretic proof for all spin of a related inequality.

Neal Madras

We consider general classes of lattice clusters, including various kinds of animals and trees on different lattices. We prove that if a given local configuration (&#34;pattern&#34;) of sites and bonds can occur in large clusters, then it occurs at least cN times in most clusters of size n, for some constant c>0. An analogous theorem for self-avoiding walks w

Christopher D. Hacon

The purpose of this paper is to give two applications of Fourier transforms and generic vanishing theorems: - we give a cohomological characterization of principal polarizations - we prove that if $X$ an abelian variety and $Θ$ a polarization of type $(1,...,1,2)$, then a general pair $(X,Θ)$ is log canonical

Slawomir Cynk

In this paper we construct 206 examples of Calabi-Yau manifolds with different Euler numbers. All constructed examples are smooth models of double coverings of $P^3$ branched along an octic surface. We allow 11 types of (not necessary isolated) singularities in the branch locus. Thus we broaden the class of examples studied in math.AG/9902057. For every cons

Valentin Vankov Iliev

Polya&#39;s fundamental enumeration theorem is generalized in terms of Schur-Macdonald&#39;s theory (S-MT) of invariant matrices. Given a permutation group $W\leq S_d$ and a one-dimensional character $χ$ of $W$, the polynomial functor $F_χ$ corresponding via S-MT to the induced monomial representation $U_χ= ind_W^{S_d}(χ)$ of $S_d$, is studied. It turns out

C. Duval, P. Lecomte, V. Ovsienko

We prove the existence and the uniqueness of a conformally equivariant symbol calculus and quantization on any conformally flat pseudo-Riemannian manifold $(M,\rg)$. In other words, we establish a canonical isomorphism between the spaces of polynomials on $T^*M$ and of differential operators on tensor densities over $M$, both viewed as modules over the Lie a

Naihuan Jing, James J. Zhang

We prove Auslander-Gorenstein and $\GKdim$-Macaulay properties for certain invariant subrings of some quantum algebras, the Weyl algebras, and the universal enveloping algebras of finite dimensional Lie algebras.

Sze-Shiang Feng, Yi-Shi Duan

We obtain a generally covariant conservation law of energy-momentum for gravitational anyons by the general displacement transform. The energy-momentum currents have also superpotentials and are therefore identically conserved. It is shown that for Deser&#39;s solution and Clement&#39;s solution, the energy vanishes. The reasonableness of the definition of e

Won Tae Kim, John J. Oh, Jung Hee Park

We calculate the absorption coefficient of scalar field on the background of the two-dimensional AdS black hole, which is of relevance to Hawking radiation. For the massless scalar field, we find that there does not exist any massless radiation.

Chien-Hao Liu

M-theory suggests the study of 11-dimensional space-times compactified on some 7-manifolds. From its intimate relation to superstrings, one possible class of such 7-manifolds are those that have Calabi-Yau threefolds as boundary. In this article, we construct a special class of such 7-manifolds, named as {\it K3-Thurston} (K3T) 7-manifolds. The factor from t

T. Hambye, G. O. Koehler, P. H. Soldan

We present a new analysis of the Delta I = 1/2 rule in K --> pi pi decays and the B_K parameter. We use the 1/N_c expansion within the effective chiral lagrangian for pseudoscalar mesons and compute the hadronic matrix elements at leading and next-to-leading order in the chiral and the 1/N_c expansions. Numerically, our calculation reproduces the dominant De

W. Beenakker, F. A. Berends, A. P. Chapovsky

We present the radiative corrections to off-shell $W$-pair production, as calculated within the double-pole approximation.

William J. Marciano

The status of several precisely measured electroweak parameters is reviewed. Natural relations among them are shown to constrain the Higgs mass, m_H, as well as various ``New Physics&#39;&#39; effects. Indications of an anomalous Zb anti-b coupling are discussed. Constraints on excited W^* bosons are given.

A. Patkos, Zs. Szep

The effective theory of low frequency fluctuations of selfinteracting scalar fields is constructed in the broken symmetry phase. The theory resulting from integrating fluctuations with frequencies much above the spontanously generated mass scale $(p_0>>M)$ is found to be local. Non-local dynamics, especially Landau damping emerges under the effect of fluctua

T. Kubota, M. Wakamatsu, T. Watabe

The Pauli-Villars regularization scheme is often used for evaluating parton distributions within the framework of the chiral quark soliton model with inclusion of the vacuum polarization effects. Its simplest version with a single subtraction term should however be taken with some caution, since it does not fully get rid of divergences contained in scalar an

CP-PACS-Collaboration, :, S. Aoki, G. Boyd

We investigate effects of action improvement on the light hadron spectrum and the static quark potential in two-flavor QCD for $a^{-1} \approx 1$ GeV and $m_{PS}/m_V = 0.7-0.9$. We compare a renormalization group improved action with the plaquette action for gluons, and the SW-clover action with the Wilson action for quarks. We find a significant improvement

Ishwaree P. Neupane

A contribution of quantum vacuum to the energy momentum tensor is inevitably experienced in the present universe. One requires the presence of non-zero cosmological constant ($Λ$) to make the various observations consistent. A case of $Λ$ in the Schwarzschild de Sitter space-time shows that precession of perihelion orbit provides a sensative solar test for n

Ishwaree P. Neupane

With the basic cosmological relations that agree with the recent observations, simple expressions are suggested concerning the value of cosmological constant($Λ$). A large contribution of quantum vacuum to the energy momentum tensor does not agree with the observed cosmos. However,one requires the presence of positive $Λ$ to make the various observations con

Mattias Ohlsson, Carsten Peterson, Bo Söderberg

A mean field feedback artificial neural network algorithm is developed and explored for the set covering problem. A convenient encoding of the inequality constraints is achieved by means of a multilinear penalty function. An approximate energy minimum is obtained by iterating a set of mean field equations, in combination with annealing. The approach is numer

I. I. Mazin, D. J. Singh

Ru based perovskites demonstrate an amazing richness in their magnetic properties, including 3D and quasi-2D ferromagnetism, antiferromagnetism, and unconventional superconductivity. Tendency to ferromagnetism, stemming from the unusually large involvement of O in magnetism in ruthenates, leads to ferromagnetic spin fluctuations in Sr2RuO4 and eventually to

M. V. Sadovskii

We present calculation of optical conductivity in a simple model of electronic spectrum of two-dimensional system with &#34;hot patches&#34; on the Fermi surface, leading to non Fermi-liquid renormalization of the spectral density (pseudogap) on these patches. It is shown that this model qualitatively reproduces basic anomalies of optical experiments in the

Thomas Gramespacher, Markus Buttiker

We consider a current-carrying, phase-coherent multi-probe conductor to which a small tunneling contact is attached. We treat the conductor and the tunneling contact as a phase-coherent entity and use a Green&#39;s function formulation of the scattering approach. We show that the average current and the current fluctuations at the tunneling contact are deter

B. Götzelmann, R. Roth, S. Dietrich, M. Dijkstra

A versatile new approach for calculating the depletion potential in a hard sphere mixture is presented. This is valid for any number of components and for arbitrary densities. We describe two different routes to the depletion potential for the limit in which the density of one component goes to zero. Both routes can be implemented within density functional t

A. Gammal, T. Frederico, L. Tomio

The stability of a Bose-Einstein condensed state of trapped ultra-cold atoms is investigated under the assumption of an attractive two-body and a repulsive three-body interaction. The Ginzburg-Pitaevskii-Gross (GPG) nonlinear Schrödinger equation is extended to include an effective potential dependent on the square of the density and solved numerically for t

Ernst Helmut Brandt

The basic theory of the linear and nonlinear ac susceptibilities of type-II superconductors is outlined for various geometries, e.g. circular and elliptic disks, rings, and strips of thin films or of thicker platelets in a perpendicular magnetic field. It is shown how the linear susceptibility depends on the linear complex resistivity or on the complex penet

Grigorii P. Mikitik, Ernst Helmut Brandt

A thin superconductor platelet with elliptic shape in a perpendicular magnetic field is considered. Using a method originally applied to circular disks, we obtain an approximate analytic solution for the two-dimensional critical state of this ellipse. In the limits of the circular disk and the long strip this solution is exact, i.e. the current density is co

S. Giorgini, J. Boronat, J. Casulleras

We use a diffusion Monte Carlo method to calculate the lowest energy state of a uniform gas of bosons interacting through different model potentials, both strictly repulsive and with an attractive well. We explicitly verify that at low density the energy per particle follows a universal behavior fixed by the gas parameter na^3. In the regime of densities typ

H. J. W. Mueller-Kirsten, D. K. Park, J. M. S. Rana

A criterion is derived for the determination of parameter domains of first order phase transitions in quantum mechanical tunneling models. The criterion is tested by application to various models, in particular to some which have been used recently to explore spin tunneling in macroscopic particles. In each case agreement is found with previously heuristical

G. Grignani, A. Mattoni, P. Sodano, A. Trombettoni

Using the path integral approach, we provide an explicit derivation of the equation for the phase boundary for quantum Josephson junction arrays with offset charges and non-diagonal capacitance matrix. For the model with nearest neighbor capacitance matrix and uniform offset charge $q/2e=1/2$, we determine, in the low critical temperature expansion, the most

E. Carlon, F. Igloi, W. Selke, F. Szalma

The interfacial adsorption W at the first-order transition in two-dimensional q-state Potts models is studied. In particular, findings of Monte Carlo simulations and of density-matrix renormalization group calculations, at q= 16, are consistent with the analytic result, obtained in the Hamiltonian limit at large values of q, that W \propto t^{-1/3} on approa

Gi-Yeong Oh

We study the resonant tunneling properties of an electron through a few types of binary periodic and aperiodic multibarrier systems. Within the framework of the effective-mass approximation, we calculate the transmission coefficients to investigate the dependence of the transmission resonances on the system parameters such as the kind of aperiodicity, the ge

J. L. Tallon, G. V. M. Williams, D. J. Pringle

Comment is made on the isotope dependence of the spin gap in YBa2Cu4O8.

K. Tanaka, F. Marsiglio

The canonical BCS wave function is tested for the attractive Hubbard model. Results are presented for one dimension, and are compared with the exact solutions by the Bethe ansatz and the results from the conventional grand canonical BCS approximation, for various chain lengths, electron densities, and coupling strengths. While the exact ground state energies

Subir Sachdev

We describe the nonzero temperature (T), low frequency (ω) dynamics of the order parameter near quantum critical points in two spatial dimensions (d), with a special focus on the regime \hbarω<< k_B T. For the case of a `relativistic&#39;, O(n)-symmetric, bosonic quantum field theory we show that, for small ε=3-d, the dynamics is described by an effective cl

D. C. Cabra, M. D. Grynberg

We investigate the conditions under which a gap vanishes in the spectrum of dimerized coupled spin-1/2 chains by means of Abelian bosonization and Lanczos diagonalization techniques. Although both interchain ($J&#39;$) and dimerization ($δ$) couplings favor a gapful phase, it is shown that a suitable choice of these interactions yields massless spin excitati

G. Gerbier, J. Mallet, L. Mosca, C. Tao

This note, with its five questions, is intended to contribute to a clarification about a claimed &#34;evidence&#34; by the DAMA group of an annual modulation of the counting rate of a Dark Matter NaI(Tl) detector as due to a neutralino (SUSY-LSP) Dark Matter candidate.

A. J. Barth, A. V. Filippenko, E. C. Moran

Optical spectropolarimetry of the nucleus of the LINER NGC 1052, obtained at the Keck Observatory, reveals a rise in polarization in the wings of the H-alpha line profile. The polarization vector of H-alpha is offset by 67 degrees from the parsec-scale radio axis and by 83 degrees from the kiloparsec-scale radio axis, roughly in accord with expectations for

Stefanie Komossa, Hans Boehringer

(abridged) We present results from an analysis of the X-ray properties of the NGC 383 galaxy group based on ROSAT PSPC and HRI data. X-ray emission can be traced out to ~ 1 Mpc, the estimated virial radius of the system. We determine a total mass of 6x10^{13} M_sun for the group inside this radius with a gas mass fraction of 21%. The intragroup-gas temperatu

S. Kempf, S. Pfalzner, Th. Henning

We investigated numerically the dust growth driven by Brownian motion in a proto-planetary disc around a solar-type young stellar object. This process is considered as the first stage in the transformation of the initially micron-sized solid particles to a planetary system. In contrast to earlier studies the growth was investigated at the small particle numb

Lawrence M. Krauss, Glenn D. Starkman

Current evidence suggests that the cosmological constant is not zero, or that we live in an open universe. We examine the implications for the future under these assumptions, and find that they are striking. If the Universe is cosmological constant-dominated, our ability to probe the evolution of large scale structure will decrease with time ---presently obs

David K. Strickland, Ian R. Stevens

We obtained a long ROSAT HRI observation of the nearby dwarf starburst and Wolf-Rayet galaxy NGC 5253. Our aim was to resolve the source of the soft thermal X-ray emission seen by the ROSAT PSPC, proposed to be a luminous superbubble by Martin & Kennicutt (1995). Instead of a single superbubble, we find a complex of at least five sources of X-ray emission, a

J. Alvarez-Muñiz, E. Zas

We discuss the recent developments in the study of alternative detection possibilites offered by the radio technique and air shower arrays.

Demosthenes Kazanas, Xin-Min Hua

We present model light curves for accreting Black Hole Candidates (BHC) based on a recently proposed model for their spectro-temporal properties. According to this model, the observed light curves and aperiodic variability of BHC are due to a series of soft photon injections at random (Poisson) intervals near the compact object and their reprocessing into ha

Karl Mannheim

With the discovery of evidence for neutrino mass, a vivid gamma ray sky at multi-TeV energies, and cosmic ray particles with unexpectedly high energies, astroparticle physics currently runs through an era of rapid progress and moving frontiers. The non-vanishing neutrino mass establishes one smooth component of dark matter which does not, however, supply a c

Guido Chincarini

I present the science goals and give a brief summary of the Wide Angle X-ray survey with a Wide Field X-ray Telescope (WAXS/WFXT) mission proposal (Phase A) which will be submitted to the Italian Space Agency (ASI) following the call for proposal under the Small Satellite program. The text points out the uniqueness of the mission for the study of the evoluti

George Chapline

Flat cosmological models with a cosmological constant on the order of the Einstein-de Sitter critical density are enigmatic in the sense that there does not appear to be any natural explanation for why there should be a cosmological constant with such a magnitude. As a perhaps more natural alternative we propose a spatially homogeneous isotropic Omega=1 univ

L. D. Paniak

We introduce a general method for transforming the equations of motion following from a Das-Jevicki-Sakita Hamiltonian, with boundary conditions, into a boundary value problem in one-dimensional quantum mechanics. For the particular case of a one-dimensional chain of interacting NxN Hermitean matrices, the corresponding large N boundary value problem is mapp

Richard Easther, David A. Lowe

We propose that in time dependent backgrounds the holographic principle should be replaced by the generalized second law of thermodynamics. For isotropic open and flat universes with a fixed equation of state, the generalized second law agrees with the cosmological holographic principle proposed by Fischler and Susskind. However, in more complicated spacetim

A. Zawadowski, Jan von Delft, D. C. Ralph

We point out a novel, non-universal contribution to the dephasing rate 1/τ_ϕ\equiv γ_ϕof conduction electrons in metallic systems: scattering off non-magnetic two-level systems (TLSs) having almost degenerate Kondo ground states. In the regime Δ_{ren} < T < T_K (Δ_{ren} = renormalized level splitting, T_K = Kondo temperature), such TLSs exhibit non-Fermi-liq

Jens O. Andersen, Eric Braaten, Michael Strickland

We calculate the free energy of a hot gluon plasma to leading order in hard-thermal-loop perturbation theory. Effects associated with screening, gluon quasiparticles, and Landau damping are resummed to all orders. The ultraviolet divergences generated by the hard-thermal-loop propagator corrections can be cancelled by a temperature-independent counterterm. T

Subrata Bal, B. Sathiapalan

The high temperature limit of a system of two D-0 branes is investigated. The partition function can be expressed as a power series in $β$ (inverse temperature). The leading term in the high temperature expression of the partition function and effective potential is calculated exactly. Physical quantities like the mean square separation can also be exactly d

A. Kogut

The derivation of cosmological parameters from astrophysical data sets routinely involves operations counts which scale as O(N^3) where N is the number of data points. Currently planned missions, including MAP and Planck, will generate sky maps with N_d = 10^6 or more pixels. Simple ``brute force&#39;&#39; analysis, applied to such mega-pixel data, would req

M. Benayoun, L. DelBuono, S. Eidelman, V. N. Ivanchenko

We re-examine the problem of simultaneously describing in a consistent way all radiative and leptonic decays of light mesons (V -> P gamma, P -> V gamma, P -> gamma gamma, V -> e^+ e^-). For this purpose, we rely on the Hidden Local Symmetry model in both its anomalous and non--anomalous sectors. We show that the SU(3) symmetry breaking scheme proposed by Ba

G. P. Salam

This article demonstrates that the BFKL and CCFM equations, despite their different physical content, lead to equivalent results for any final-state observable at leading single-logarithmic order. A novel and fundamental element is the treatment also of the soft (z->1 divergent) part of the splitting function in the CCFM equation.

Denis Bernard

We present a simple exact formula for the three point velocity correlation functions in two dimensional turbulence which is valid on all scales and which interpolates between the direct and inverse cascade regimes. As expected, these correlation functions are universal in these extreme regimes. We also discuss the effect of anisotropy and friction.

Ian I. Kogan, Gloria Luzon

In this letter we shall discuss a description of non-supersymmetric four-dimensional Yang-Mills theory based on Type 0 strings recently proposed by Klebanov and Tseytlin. The three brane near-horizon geometry allows one to study the UV behaviour of the gauge theory. Following Minahan and Klebanov and Tseytlin we shall discuss how the gravity solution reprodu

Valter Moretti

We consider the problem of the symmetry of the off-diagonal heat-kernel coefficients as well as the coefficients corresponding to the short-distance-divergent part of the Hadamard expansion in general smooth (analytic or not) manifolds. The requirement of such a symmetry played a central rôle in the theory of the point-splitting one-loop renormalization of t

Mark Lee, J. G. Massey, V. L. Nguyen, B. I. Shklovskii

Electron tunneling experiments are used to probe Coulomb correlation effects in the single-particle density-of-states (DOS) of boron-doped silicon crystals near the critical density of the metal-insulator transition (MIT). At low energies, a DOS measurement distinguishes between insulating and metallic samples with densities 10 to 15 % on either side of the

Doron Cohen

We make the first steps towards a generic theory for energy spreading and quantum dissipation. The Wall formula for the calculation of friction in nuclear physics and the Drude formula for the calculation of conductivity in mesoscopic physics can be regarded as two special results of the general formulation. We assume a time-dependent Hamiltonian $H(Q,P;x(t)

Oswaldo M. Del Cima, Daniel H. T. Franco, Olivier Piguet

We apply the formalism of extended BRS symmetry to the investigation of the gauge dependence of the effective potential in a spontaneously symmetry broken gauge theory. This formalism, which includes a set of Grassmann parameters defined as the BRS variations of the gauge-fixing parameters, allows us to derive in a quick and unambiguous way the related Niels

Peter Molnar, Martin W. Gruenewald

Triple gauge boson couplings between Z, gamma and the W boson are determined by exploiting their impact on radiative corrections to fermion-pair production in e+e- interactions at centre-of-mass energies near the Z-pole. Recent values of observables in the electroweak part of the Standard model are used to determine the four parameters epsilon_1, epsilon_2,

D. O. Riska, G. E. Brown

The two-pion exchange interaction between constituent quarks is shown to enhance the effect of the the isospin dependent spin-spin component of the one-pion exchange interaction, and to cancel out its tensor component. It therefore provides a partial explanation for the phenomenological observation that the hyperfine interaction between constituent quarks is

A. Shuvaev

Using the conformal invariance the leading-log evolution of the off-forward structure function is reduced to the forward evolution described by the conventional DGLAP equation. The method relies on the fact that the anomalous dimensions of the Gegenbauer moments of the off-forward distribution are independent on the asymmetry, or skewedness, parameter and eq

Sergei M. Kopeikin, Gerhard Schafer

The Lorentz covariant theory of propagation of light in the (weak) gravitational fields of N-body systems consisting of arbitrarily moving point-like bodies with constant masses is constructed. The theory is based on the Lienard-Wiechert presentation of the metric tensor. A new approach for integrating the equations of motion of light particles depending on

S. Yamaguchi, Y. Ishimoto, K. Sugiyama

We study a Wess-Zumino-Witten model with target space AdS_3 x (S^3 x S^3 x S^1)/Z_2. This allows us to construct space-time N=3 superconformal theories. By combining left-, and right-moving parts through a GSO and a Z_2 projections, a new asymmetric (N,\bar{N})=(3,1) model is obtained. It has an extra gauge (affine) SU(2) symmetry in the target space of the

Ikaros Bigi, Nikolai Uraltsev

We address nonperturbative power corrections to inclusive decay widths of heavy flavor hadrons in the context of the &#39;t Hooft model (two-dimensional QCD at N_c->oo), with the emphasis on the spectator-dependent effects sensitive to the flavor of the spectator. The summation of exclusive widths is performed analytically using the `t Hooft equation. We sho

H. -W. Lee

We study phase coherent transport in a single channel system using the scattering matrix approach. It is shown that identical vanishing of the transmission amplitude occurs generically in quasi-1D systems if the time-reversal is a good symmetry. The transmission zeros naturally lead to abrupt phase changes (without any intrinsic energy scale) and in-phase re

Sang Pyo Kim

We propose a method to construct quantum theory of matter fields in a topology changing universe. Analytic continuation of the semiclassical gravity of a Lorentzian geometry leads to a non-unitary Schrödinger equation in a Euclidean region of spacetime, which does not have a direct interpretation of quantum theory of the Minkowski spacetime. In this Euclidea

G. Madejski, M. Sikora, T. Jaffe, M. Blazejowski

This paper reports on the X-ray emission from BL Lacertae during its July 1997 outburst as observed with the Rossi X-ray Timing Explorer (RXTE), compares the RXTE data to previous measurements, and interprets the overall electromagnetic emission in the context of the currently popular theoretical models. The source is bright and variable, with the 2 - 10 keV

Abner Soffer

Several time-independent methods have been devised for measuring the phase gamma of the Cabibbo-Kobayashi-Maskawa unitarity triangle. It is shown that such measurements generally suffer from discrete ambiguity which is at least 8-fold, not 4-fold as commonly stated. This has serious experimental implications, which are explored in methods involving B->DK dec

O. L. G. Peres, A. Y. Smirnov

Neutrino oscillations with parameters relevant for the large mixing solution of the solar neutrino problem ($Δm^2_{21} = (2 - 20) \cdot 10^{-5}$ eV$^2$, $\sin^2 2θ_{12} > 0.65$) can lead to observable (up to 10 - 12 %) excess of the e-like events in the sub-GeV atmospheric neutrino sample. The excess has a weak zenith angle dependence in the low energy part

Y. S. Lee, R. J. Birgeneau, M. A. Kastner, Y. Endoh

We report neutron scattering measurements of spin density wave order within the superconducting state of a single crystal of predominately stage-4 La2CuO4+y with a Tc(onset) of 42 K. The low temperature elastic magnetic scattering is incommensurate with the lattice and is characterized by long-range order in the copper-oxide plane with the spin direction ide

N. Gisin, S. Wolf

When the 4-state or the 6-state protocol of quantum cryptography is carried out on a noisy (i.e. realistic) quantum channel, then the raw key has to be processed to reduce the information of an adversary Eve down to an arbitrarily low value, providing Alice and Bob with a secret key. In principle, quantum algorithms as well as classical algorithms can be use

Jung Kon Kim, Sang Pyo Kim, Kwang-Gi Park

We find a one-parameter Gaussian state for an anharmonic oscillator with quadratic and quartic terms, which depends on the energy expectation value. For the weak coupling constant, the Gaussian state is a squeezed state of the vacuum state. However, for the strong coupling constant, the Gaussian state represents a different kind of condensation of bosonic pa

Xiaodong Chen

Using 2 more time variables as the quantum hidden variables, we derive the equation of Dirac field under the principle of classical physics, then we extend our method into the quantum fields with arbitrary spin number. The spin of particle is shown naturally as the topological property of 3-dimensional time + 3-dimensional space . One will find that the quan

M. Vilches, J. C. Zapata, D. Guirado, D. Fernández

We propose and analyze in detail a method to measure the in-air spatial spread parameter of clinical electron beams. Measurements are performed at the center of the beam and below the adjustable collimators sited in asymmetrical configuration in order to avoid the distortions due to the presence of the applicator. The main advantage of our procedure lies in

Tom Ostoma, Mike Trushyk

The downward acceleration of the virtual electrically charged fermion particles of the quantum vacuum is responsible for the Einstein Weak Equivalence Principle and for our perception of 4D space-time curvature near the earth. Since the virtual fermion particles of the quantum vacuum (virtual electrons for example) possess mass, we assume that during their s

Jyotipratim Ray Chaudhuri, Suman Kumar Banik, Bimalendu Deb, Deb Shankar Ray

Based on the system-reservoir description we propose a simple solvable microscopic model for a nonequilibrium bath. This captures the essential features of a nonstationary quantum Markov process. We establish an appropriate generalization of the fluctuation-dissipation relation pertaining to this process and explore the essential modifications of the Bloch e

G. Brida, M. Genovese, C. Novero

We report the measurement of the photons flux produced in parametric down-conversion, performed in photon counting regime with actively quenched silicon avalanche photodiodes as single photon detectors. Measurements are done with the detector in a well defined geometrical and spectral situation. By comparison of the experimental data with the theory, a value

T. Dauxois, W. R. Young

Using a matched asymptotic expansion we analyze the two-dimensional, near- critical reflection of a weakly nonlinear, internal gravity wave from a sloping boundary in a uniformly stratified fluid. Taking a distinguished limit in which the amplitude of the incident wave, the dissipation, and the departure from criticality are all small, we obtain a reduced de

Eduardo Bauer, Antonio M. Lallena

We investigate the extent to which the nuclear transverse response to electron scattering in the quasielastic region, evaluated in the random-phase approximation can be described by ring approximation calculations. Different effective interactions based on a standard model of the type g&#39;+V_pi+V_rho are employed. For each momentum transfer, we have obtain

L. Tiator, D. Drechsel, G. Knoechlein, C. Bennhold

A combined analysis of new eta photoproduction data for total and differential cross sections, target asymmetry and photon asymmetry is presented. Using a few reasonable assumptions we perform the first model-independent analysis of the E0+, E2- and M2- eta photoproduction multipoles. Making use of the well-known A3/2 helicity amplitude of the D13(1520) stat

R. Bieber, C. Wagemans, G. Goeminne, J. Wagemans

The 37Ar(n_th,alpha)34S and 37Ar(n_th,p)37Cl reactions were studied at the high flux reactor of the ILL in Grenoble. For the 37Ar(n_th,alpha_0) and 37Ar(n_th,p) reaction cross sections, values of (1070+/-80)b and (37+/-4)b, respectively, were obtained. Both values are about a factor 2 smaller than results of older measurements. The observed suppression of th

WA98 Collaboration, M. M. Aggarwal

The directed flow of protons and positive pions have been studied in 158 A GeV Pb + Pb collisions. A directed flow analysis of the rapidity dependence of the average transverse momentum projected onto the reaction plane is presented for semi-central collisions with impact parameters of approximately 8 fm, where the flow effect is largest. The magnitude of th

Alexander Brudnyi

The paper presents a classification theorem for the class of flat connections with triangular (0,1)-components on a topologically trivial complex vector bundle over a compact Kahler manifold. As a consequence we obtain several results on the structure of Kähler groups, i.e., the fundamental groups of compact Kahler manifolds.

Brendan Hassett, Yuri Tschinkel

Equivariant compactifications of reductive groups can be described by combinatorial data. On the other hand, equivariant compactifications of the additive group G^n_a are more complicated in at least two respects. First, they often admit moduli. Second, even simple varieties (like projective spaces) admit many different structures as equivariant compactifica

Alexander Kirillov,, Alain Lascoux

We show that the Kazhdan-Lusztig basis elements $C_w$ of the Hecke algebra of the symmetric group, when $w \in S_n$ corresponds to a Schubert subvariety of a Grassmann variety, can be written as a product of factors of the form $T_i+f_j(v)$, where $f_j$ are rational functions.