April 1998 arXiv papers — page 3

Mucio A. Continentino

Recently we have shown that a one-parameter scaling, the Coherence Temperature, describes the physical behavior of several heavy fermions in a region of their phase diagram. In this paper we fully characterize this region, obtaining the uniform susceptibility, the resistivity and the specific heat. This allows for an explicit evaluation of the Wilson and the

M. E. J. Newman, R. G. Palmer

We examine the sources of error in the histogram reweighting method for Monte Carlo data analysis. We demonstrate that, in addition to the standard statistical error which has been studied elsewhere, there are two other sources of error, one arising through correlations in the reweighted samples, and one arising from the finite range of energies sampled by a

Udo Siewert, Lutz Schimansky-Geier

The two-state model of stochastic resonance is extended to a chain of coupled two-state elements governed by the dynamics of Glauber's stochastic Ising model. Appropriate assumptions on the model parameters turn the chain into a prototype system of coupled stochastic resonators. In a weak-signal limit analytical expressions are derived for the spectral p

I. Borukhov, D. Andelman, H. Orland

The behavior of polyelectrolytes and polyampholytes in semi-dilute solutions is investigated theoretically. Various statistical charge distributions along the polyelectrolyte chains are considered: smeared, annealed, permuted and quenched. Annealed polyampholytes are also considered. Path integral formulation was used to derive mean field free energies for t

Jonathan Doye, Daan Frenkel

We have studied the structure and free energy landscape of a semi-flexible lattice-polymer in the presence of a surface. At low temperatures coexistence of two-dimensional integer-folded crystals is observed. As the temperature is increased there is a transition from these crystalline configurations to a disordered coil adsorbed onto the surface. The polymer

T. Herrmann, M. Potthoff, W. Nolting

The temperature-driven reorientation transition which, up to now, has been studied by use of Heisenberg-type models only, is investigated within an itinerant-electron model. We consider the Hubbard model for a thin fcc(100) film together with the dipole interaction and a layer-dependent anisotropy field. The isotropic part of the model is treated by use of a

R. Hilfer

The established macroscopic equations of motion for two phase immiscible displacement in porous media are known to be physically incomplete because they do not contain the surface tension and surface areas governing capillary phenomena. Therefore a more general system of macroscopic equations is derived here which incorporates the spatiotemporal variation of

Luis Brey

We study the effect that the electron-electron interaction has on the properties of a multilayer electron system. We consider the case corresponding to filling factor unity in each layer. We find that as a function of the sample parameters the system has ferromagnetic, canted antiferromagnetic or paramagnetic interlayer spin correlations. These three ground

A. S. Alexandrov, G. J. Kaye

We propose a microscopic explanation of the pseudogap features discovered in the normal state specific heat and magnetic susceptibility of cuprates. In the framework of the bipolaron theory of high-Tc superconductors we explain the magnitude of the carrier specific heat and susceptibility as well as their universal scaling with temperature over a wide range

A. S. Alexandrov

A single-particle spectral density is proposed for cuprates taking into account the bipolaron formation, realistic band structure, thermal fluctuations and disorder. Tunnelling and photoemission (PES) spectra are described, including the temperature independent gap observed both in the superconducting and normal states, the emission/injection asymmetry, the

A. J. Webster, M. E. Cates

We consider an emulsion whose droplets contain a trapped species (insoluble in the continuous phase), and study the emulsion's stability against coarsening via Lifshitz-Slyozov dynamics (Ostwald Ripening). Extending an earlier treatment by Kabalnov et al(Colloids and Surfaces, 24,(1987), 19-32), we derive a general condition on the mean initial droplet v

Gertjan van Noord

The paper discusses the problem of determinising finite-state automata containing large numbers of epsilon-moves. Experiments with finite-state approximations of natural language grammars often give rise to very large automata with a very large number of epsilon-moves. The paper identifies three subset construction algorithms which treat epsilon-moves. A num

Andreas Schmitz, Thomas Schreiber

We generalize the method of surrogate data of testing for nonlinearity in time series to the case that the data are sampled with uneven time intervals. The null hypothesis will be that the data have been generated by a linear stochastic process, possibly rescaled, and sampled at times chosen independently from the generating process. The surrogate data are g

Thomas W. Berghoefer, Stuart Bowyer, Richard Lieu, Jens Knude

We have used the Deep Survey telescope of EUVE to investigate shadows in the diffuse EUV/Soft X-Ray background cast by clouds in the interstellar medium. We confirm the existence of a shadow previously reported, and provide evidence for two new shadows. We used IRAS data to identify the clouds producing these shadows and to determine their optical depth to E

R. G. Carlberg, H. K. C. Yee, E. Ellingson, S. L. Morris

The CNOC redshift survey of galaxy clusters measures Omega_M from Omega_e(z)= M/L x j/ρ_c which can be applied on a cluster-by-cluster basis. The mass-to-light ratios, M/L, are estimated from rich galaxy clusters, corrected to the field population over the 0.18 to 0.55 redshift range. Since the luminosity density depends on cosmological volumes, the resultin

Li-Xin Li, J. Richard Gott, III

In this paper we investigate a model of an inflationary universe in Kaluza-Klein theory, which is a four-dimensional de Sitter space plus a one-dimensional compactified internal space. We find that the energy scale for inflation can be predicted from the fine-structure constant in a self-consistent solution of the semi-classical Einstein equations including

Stuart Bowyer, Thomas W. Berghoefer

We have examined the hypothesis that the majority of the diffuse EUV flux in the Coma cluster is due to inverse Compton scattering of low energy cosmic ray electrons (0.16 < epsilon < 0.31 GeV) against the 3K black-body background. We present data on the two-dimensional spatial distribution of the EUV flux and show that these data provide strong support for

P. J. Armitage, J. R. Murray

We consider the implications of the detection of spiral structure in the accretion disc of the binary IP Pegasi. We use numerical simulations of the development of a disc outburst to construct predicted Doppler tomograms, which are found to be in close agreement with the observations if the spiral pattern arises as a transient feature when the disc expands v

I. Negueruela, P. Reig, M. J. Coe, J. Fabregat

We investigate the spectroscopic characteristics of the optical components of Be/X-ray binary systems, using data collected during our seven-year monitoring campaign. We find examples of major changes in the emission line profiles associated with Type II X-ray outbursts, later developing into V/R variability cycles. We show that the time-scales for V/R varia

G. Mark Voit, Megan Donahue

X-ray temperature measurements of clusters of galaxies are now reaching to redshifts high enough to constrain Omega_0. A redshift-dependent relation that maps these X-ray temperatures to the virial masses of clusters is an essential ingredient when one is trying to determine cosmological parameters from cluster evolution. Most such relations assume that clus

Peter Goldreich, Yanqin Wu

We analyze the stability of g-modes in variable white dwarfs with hydrogen envelopes. In these stars, the radiative layer contributes to mode damping because its opacity decreases upon compression and the amplitude of the Lagrangian pressure perturbation increases outward. The overlying convective envelope is the seat of mode excitation because it acts as an

F. Combes, T. Wiklind

We report a tentative detection with the IRAM 30m telescope of the LiH molecule in absorption in front of the lensed quasar B0218+357. We have searched for the J = 0 -- 1 rotational line of lithium hydride at 444 GHz (redshifted to 263 GHz). The line, if detected, is optically thin, very narrow, and corresponds to a column density of N(LiH) = 1.6 10$^{12}$ c

Andrea Cimatti, Paola Andreani, Huub Röttgering, Remo Tilanus

Near-infrared surveys have revealed a substantial population of enigmatic faint galaxies with extremely red optical-to-near-infrared colours and with a sky surface density comparable to that of faint quasars. There are two scenarios for these extreme colours: (i) these distant galaxies have formed virtually all their stars at very high redshifts and, due to

Hernán Muriel, Carlos A. Valotto, Diego G. Lambas

We compute the luminosity function of galaxies in groups. The data consists in two samples of groups of galaxies selected in distance and redshift space comprising a total number of 66 groups. The assignment of galaxies to the groups were derived from the Edinburgh-Durham Southern Galaxy Catalog, considering a limiting apparent magnitude $m_{lim}=19.4$. We f

A. Wolter, A. Comastri, G. Ghisellini, P. Giommi

We present X-ray spectra obtained with BeppoSAX (Satellite per Astronomia X) of 10 BL Lac objects, selected from the Einstein Medium Sensitivity and Slew Surveys. We find that in about half of the objects a fit in the 0.1-10 keV range with a single power law and free absorption yields values of NH larger than the Galactic ones. In most of these cases, howeve

Duncan Forbes, Ray Norris

We have produced radio maps, using the ATCA, of the central regions of six southern Seyfert 2 galaxies (NGC 1365, 4945, 6221, 6810, 7582, and Circinus) with circumnuclear star formation, to estimate the relative contribution of star formation activity compared to activity from the active galactic nucleus (AGN). The radio morphologies range from extended diff

P. Montegriffo, F. R. Ferraro, L. Origlia, F. Fusi Pecci

We present new determinations of bolometric corrections and effective temperature scales as a function of infrared and optical colors, using a large database of photometric observations of about 6500 Population II giants in Galactic Globular Clusters (GGCs), covering a wide range in metallicity (-2.0<[Fe/H]<0.0). New relations for BC_K vs (V-K), (J-K) and BC

N. Fornengo

Direct and indirect detection rates of relic neutralinos are reviewed in the framework of the Minimal Supersymmetric Standard Model. The theoretical estimates are compared with the most recent experimental limits from low-background detectors and neutrino telescopes. The properties of neutralino under the hypothesis that preliminary experimental results of t

Piercarlo Bonifacio, Paolo Molaro

Lithium is one of the few primordially produced elements. The value of the primordial Li is taken to be that observed in metal--poor dwarfs, where it is not contaminated by stellar Li sources which act on longer time scales. The atmospheric abundance is currently derived from the LiI 6707 Angstroem resonance transition and the validity of the models employed

K. J. Brooks, J. B. Whiteoak, J. W. V. Storey

The Carina Nebula is an extremely bright southern HII region embedded in a giant molecular cloud and contains some of the most massive stars known in our Galaxy. We are undertaking a multi-wavelength study of the Carina Nebula in order to examine the detailed kinematics and distribution of the molecular and ionised gas, and to look for further evidence of on

Nir J. Shaviv

The effects that large scale fluctuations had on small scale isothermal modes at the epoch of recombination are analysed. We find that: (a) Albeit the fact that primordial fluctuations were at this epoch still well in the linear regime, a significant nonlinear radiation hydrodynamic interaction could have taken place. (b) Short wavelength isothermal fluctuat

G. Fossati, F. Haardt

The apparency of low energy absorption features in Blazar LECS spectra has been reported during the early phase of the BeppoSAX mission (e.g. by Grandi et al. 1997 for 3C~273 SVP data; Giommi et al. 1997 for PKS 2155--304 SVP data), with data reduction and analysis tools released prior to July 1997. We set up a robust method to investigate the reliability of

J. D. Cohn

Scalar and gravity wave subcurvature fluctuations are calculated for a background approximating the Hawking and Turok open universe model. The gravity wave cosmic microwave background contribution is finite and it appears that a normalizable scalar supercurvature mode is possible in some regions of parameter space.

Tom Banks, Michael B. Green

We show that five-dimensional anti de-Sitter space remains a solution to low-energy type IIB supergravity when the leading higher-derivative corrections to the classical supergravity (which are non-perturbative in the string coupling) are included. Furthermore, at this order in the low energy expansion of the IIB theory the graviton two-point and three-point

Kimyeong Lee, Piljin Yi

We construct and explore BPS states that preserve 1/4 of supersymmetry in N=4 Yang-Mills theories. Such states are also realized as three-pronged strings ending on D3-branes. We correct the electric part of the BPS equation and relate its solutions to the unbroken abelian gauge group generators. Generic 1/4-BPS solitons are not spherically symmetric, but con

W. Lerche, S. Stieberger

We compute certain one-loop corrections to F^4 couplings of the heterotic string compactified on T^2, and show that they can be characterized by holomorphic prepotentials. We then discuss how some of these couplings can be obtained in F-theory, or more precisely from 7-brane geometry in type IIB language. We in particular study theories with E_8 x E_8 and SO

Daniel E. Holz, M. Coleman Miller, Jean M. Quashnock

The lack of bright host galaxies in several recently examined gamma-ray burst (GRB) error boxes suggests that the redshifts of cosmological GRBs may be significantly higher than previously believed. On the other hand, the non-detection of multiple images in the BATSE 4B catalog implies an upper limit on the average redshift <z> of GRBs. Here, we calculate an

Greg Huey, Limin Wang, R. Dave, R. R. Caldwell

Some form of missing energy may account for the difference between the observed cosmic matter density and the critical density. Two leading candidates are a cosmological constant and quintessence (a time-varying, inhomogenous component with negative pressure). We show that an ideal, full-sky cosmic background anisotropy experiment may not be able to distingu

J. C. Montero, V. Pleitez, O. Ravinez

We consider the implementation of CP violation in the context of 331 models. In particular we treat a model where only three scalar triplets are needed in order to give all fermions a mass while keeping neutrino massless. In this case all CP violation is provided by the scalar sector.

Alex Lewin, Andreas Albrecht, Joao Magueijo

In this paper we propose a new statistic capable of detecting non-Gaussianity in the CMB. The statistic is defined in Fourier space, and therefore naturally separates angular scales. It consists of taking another Fourier transform, in angle, over the Fourier modes within a given ring of scales. Like other Fourier space statistics, our statistic outdoes more

S. Rombouts, K. Heyde, N. Jachowicz

A mean-field plus pairing model for atomic nuclei in the Fe region was studied using a finite-temperature quantum Monte-Carlo method. We present results for thermodynamical quantities such as the internal energy and the specific heat. These results give indications of a phase transition related to the pairing amongst nucleons, around temperatures of 0.7 MeV.

M. Alford, K. Rajagopal, F. Wilczek

We propose a symmetry breaking scheme for QCD with three massless quarks at high baryon density wherein the color and flavor SU(3)_color times SU(3)_L times SU(3)_R symmetries are broken down to the diagonal subgroup SU(3)_{color+L+R} by the formation of a condensate of quark Cooper pairs. We discuss general properties that follow from this hypothesis, inclu

M. P. Nightingale, C. J. Umrigar

In this review we discuss, from a unified point of view, a variety of Monte Carlo methods used to solve eigenvalue problems in statistical mechanics and quantum mechanics. Although the applications of these methods differ widely, the underlying mathematics is quite similar in that they are stochastic implementations of the power method. In all cases, optimiz

Rabindra N. Mohapatra, Vigdor L. Teplitz

We find constraints on heavy, stable, strongly interacting massive particles (X) from searches for anomalous nuclei containing them, formed during primordial nucleosynthesis. Using existing data, we obtain a limit on the abundance ratio $C_X\equiv n_X/n_B$ in the range of $3\times 10^{-8}$ to $3\times 10^{-13}$ for masses up to 10 TeV if the $X-N$ interactio

Randall D. Kamien

We study force-free configurations of Abrikosov flux lines in the line-liquid and line-crystal limit, near the melting transition at H_m. We show that the condition for zero force configurations can be solved by appealing to the structure of chiral liquid crystalline phases.

W. Belzig, C. Bruder, A. L. Fauchere

We investigate the magnetic response of normal-metal--superconductor proximity systems for arbitrary concentrations of impurities and at arbitrary temperatures. Using the quasiclassical theory a general linear-response formula is derived which yields a non-local current-field relation in terms of the zero-field Green&#39;s functions. Various regimes between

I. L. Buchbinder, S. M. Kuzenko

We analyse the one-loop effective action of N=4 SYM theory in the framework of the background field formalism in N=2 harmonic superspace. For the case of on-shell background N=2 vector multiplet we prove that the effective action is free of harmonic singularities. When the lowest N=1 superspace component of the N=2 vector multiplet is switched off, the effec

A. Isacsson, L. Y. Gorelik, M. V. Voinova, B. Kasemo

We study a simple model of a self-assembled, room temperature Coulomb-blockade nanostructure containing a metallic nanocrystal or grain connected by soft molecular links to two metallic electrodes. Self-excitation of periodic grain vibrations at 10 - 100 GHz is shown to be possible for a sufficiently large bias voltage leading to a novel `shuttle mechanism&#

S. Deger, A. Kaya, E. Sezgin, P. Sundell

The complete spectrum of D=6, N=4b supergravity with n tensor multiplets compactified on AdS_3 x S^3 is determined. The D=6 theory obtained from the K_3 compactification of Type IIB string requires that n=21, but we let n be arbitrary. The superalgebra that underlies the symmetry of the resulting supergravity theory in AdS_3 coupled to matter is SU(1,1|2)_L

Tomohiro Matsuda

Many models for dynamical supersymmetry breaking have the domain wall solution of the Kovner-Shifman type and therefore contain the potential cosmological domain wall problem.We show that the degeneracy of the vacua is lifted in any model in which the cosmological constant is fine-tuned to zero through an explicit $Z_{n}^{R}$ symmetry breaking constant in th

Lu-Ming Duan, Guang-Can Guo

We construct a probabilistic quantum cloning machine by a general unitary-reduction operation. With a postselection of the measurement results, the machine yields faithful copies of the input states. It is shown that the states secretly chosen from a certain set $\$=\left\{\left| Ψ_1\right> ,\left| Ψ_2\right> ,... ,\left| Ψ_n\right> \right\} $ can be probabi

B. d&#39;Espagnat

Aharonov and Anandan&#39;s claim that the notion of ``proper mixture&#39;&#39; is improper is shown to be unjustified. The point is made that if a purely operationalist standpoint is taken the three difficulties these authors describe relatively to the conventional interpretation of density matrices in fact vanish. It is noted that nevertheless it is very di

Phil Gossett

If one modifies the laws of Quantum Mechanics to allow nonlinear evolution of quantum states, this paper shows that NP-complete problems would be efficiently solvable in polynomial time with bounded probability (NP in BQP). With that (admittedly very unlikely) assumption, this is demonstrated by describing a polynomially large network of quantum gates that s

W. G. Unruh

Stapp has recently argued from a version of the Hardy type experiments that quantum mechanics must be non-local, independent of any additional assumptions like realism or hidden variables. I argue that either his conclusions do not follow from his assumptions, or that his assumptions are not true of quantum mechanics and can be interpreted as assigning an un

J. L. Lebowitz, A. Rokhlenko

We study the long time behavior of light particles, e.g. an electron swarm in which Coulomb interactions are unimportant, subjected to an external field and elastic collisions with an inert neutral gas. The time evolution of the velocity and position distribution function is described by a linear Boltzmann equation (LBE). The small ratio of electron to neutr

Marcos Alvarez

The Aharonov-Bohm scattering amplitude is calculated in the context of planar gravity with localized sources which also carry a magnetic flux. These sources cause space-time to develop conical singularities at their location, thus introducing novel effects in the scattering of electrically charged particles. The behaviour of the wave function in the proximit

S. Goldstein, J. L. Lebowitz, Y. Sinai

We consider a dynamical system with state space $M$, a smooth, compact subset of some ${\Bbb R}^n$, and evolution given by $T_t$, $x_t = T_t x$, $x \in M$; $T_t$ is invertible and the time $t$ may be discrete, $t \in {\Bbb Z}$, $T_t = T^t$, or continuous, $t \in {\Bbb R}$. Here we show that starting with a continuous positive initial probability density $ρ(x

A. Carey, K. Hannabuss, V. Mathai

We study both the continuous model and the discrete model of the integer quantum Hall effect on the hyperbolic plane in the presence of disorder, extending the results of an earlier paper [CHMM]. Here we model impurities, that is we consider the effect of a random or almost periodic potential as opposed to just periodic potentials. The Hall conductance is id

Alexander Molev

A basis for each finite-dimensional irreducible representation of the symplectic Lie algebra sp(2n) is constructed. The basis vectors are expressed in terms of the Mickelsson lowering operators. Explicit formulas for the matrix elements of generators of sp(2n) in this basis are given. The basis is natural from the viewpoint of the representation theory of th

Nathan M. Dunfield

This paper gives examples of hyperbolic 3-manifolds whose SL(2,C) character varieties have ideal points whose associated roots of unity are not 1 or -1. This answers a question of Cooper, Culler, Gillet, Long, and Shalen as to whether roots of unity other than 1 and -1 occur.

Miao Li

It is shown that a pair of vortex and anti-vortex is completely screened in 2+1 dimensional Yang-Mills theory and 3+1 dimensional Yang-Mills theory in the strong coupling limit, based on the recent conjecture of Maldacena. This is consistent with the fact that these theories exhibit confinement.

I. Sachs

The low energy decay rates of four- and five dimensional dyonic black holes in string theory are equivalently described in terms of an effective near horizon AdS_3 (BTZ) black hole. It is then argued that AdS_3 gravity provides an universal microscopic description of the low energy dynamics these black holes.

G. Lambiase, G. Papini

Exact gauge structures arise in the evolution of spin-1/2 particles in conformally flat space-times. The corresponding Berry potentials can be Abelian or non-Abelian depending on the mass degeneracy of the system considered. Examples include de Sitter universes and maximal acceleration.

Alejandro Rivero

It is pointed out that ambiguities in the regularization of actions with second derivatives seem to happen with the same multiplicity that the standard model of elementary particles

B. M. Zupnik

Three-dimensional field theories with N=3 and N=4 supersymmetries are considered in the framework of the harmonic-superspace approach. Analytic superspaces of these supersymmetries are similar; however, the geometry of gauge theories with the manifest N=3 is richer and admits construction of the topological mass term.

V. M. Belyaev

The role of Z_N symmetry in gauge theories at finite temperatures is discussed. This symmetry is studied in terms of A_0-effective potential. We consider two- and four-dimensional models where the question on physical interpretation of minima of $A_0$-effective potential can be considered exactly. It is shown that the correct result for the partition functio

Paul H. Frampton

In this talk I begin with some general discussion of the history of CP violation, then move on to aspects of a spontaneous CP violation model including the production of new particles at LHC, implications for B decay, generalized Cabibbo mixing and a reevaluation of kaon CP violation. Finally there is a summary.

S. M. Bilenky, C. Giunti, W. Grimus, T. Schwetz

We investigate the Big-Bang Nucleosynthesis constraints on neutrino mixing in the framework of the two four-neutrino schemes that are favored by the results of neutrino oscillation experiments. We discuss the implications of these constraints for terrestrial short and long-baseline neutrino oscillation experiments and we present some possibilities of testing

Sergio Lupia, Wolfgang Ochs, Jacek Wosiek

It is shown that the gluons produced with small transverse momenta $k_\perp$ inside a jet ($k_\perp <k_\perp^{cut}$, $k_\perp^{cut} \to 0$) are independently emitted from the primary parton, as QCD coherence suppresses their showering. Consequently, the low $k_{\perp}$ gluons follow a Poisson distribution, very much like the soft photons radiated by a charge

S. V. Molodtsov, A. M. Snigirev, G. M. Zinovjev

The relevance of the dipole configurations of quarks in forming nucleus structure functions is discussed. It is shown that a radiation generated by dipole configurations while moving relativistically along their axises is described by distributions which are finite and infrared stable in low transverse momentum region. It is argued that there is an exponenti

B. Machet

Indirect CP violation is analyzed in the framework of the electroweak gauge theory of J=0 mesons proposed in ref.[1], in which they transform like composite fermion-antifermion operators by the chiral U(N)left x U(N)right group and by the SU(2)left x U(1) gauge group of the Glashow-Salam-Weinberg model. It is shown that, in this model where, in particular, m

U. Aglietti, M. Ciuchini, G. Corbo&#39;, E. Franco

We present a method to compute, by numerical simulations of lattice QCD, the inclusive semileptonic differential decay rates of heavy hadrons and the structure functions which occur in deep inelastic scattering. The method is based on first principles and does not require any model assumption. It allows the prediction of the differential rate in B semilepton

Jan Bartelski, Wojciech Krolikowski, Miroslaw Kurzela

We have performed several fits to find the ratio $R=σ_{L}/σ_{T}$ in different phenomenological models. Our fits seem to leave no room for possible admixture of scalar partons inside the nucleon.

Vladimir A. Petrov

A brief ideological and historical review of problems of high energy diffractive scattering is given.

Q. H. Zhang

Multi-pion correlations and wavepacket size effects on the pion multiplicity distribution, pion momentum distribution and two-pion interferometry are studied. It is shown that multi-pion Bose-Einstein correlations and the wavepacket size cause an abundance of pions at low momentum, increase the mean pion multiplicity and decrease both the apparent radius of

T. Hattori, T. Hasuike, S. Wakaizumi

We analyze in the four-generation model the first measurement of the branching ratio of rare kaon decay K^+\toπ^+ν\barν, using the constraints from Δm_K, ε_K, B_d-\bar{B_d} mixing, Γ(b\to sγ), B_s-\bar{B_s} mixing, D^0-\bar{D^0} mixing, B(K_L\toπ^0ν\barν) and B(K_L\toμ\barμ), and study its effects on the unitarity triangle. With the results of searching for

M. Hashimoto, K. -I. Izawa, M. Yamaguchi, T. Yanagida

We derive cosmological constraints on the masses of generic scalar fields which decay only through gravitationally suppressed interactions into unstable gravitinos and ordinary particles in the supersymmetric standard model. For the gravitino mass 100GeV-1TeV, the scalar masses should be larger than 100TeV to keep the success of big-bang nucleosynthesis if n

C. Boros, J. T. Londergan, A. W. Thomas

We discuss shadowing corrections to the structure function $F_2$ in neutrino deep-inelastic scattering on heavy nuclear targets. In particular, we examine the role played by shadowing in the comparison of the structure functions $F_2$ measured in neutrino and muon deep inelastic scattering. The importance of shadowing corrections in the determination of the

Susumu Koretune

We show that the chiral $SU(n)\otimes SU(n)$ flavor symmetry on the null-plane severely restricts the sea quarks in the baryon octet. It predicts large asymmetry for the light sea quarks $(u,d,s)$, and universality and abundance for the heavy sea quarks. Further it is shown that existence of the heavy sea quarks constrained by the same symmetry reduces the t

Karen Lingel, Tomasz Skwarnicki, James G. Smith

Penguin, or loop, decays of B mesons induce effective flavor-changing neutral currents, which are forbidden at tree level in the Standard Model. These decays give special insight into the CKM matrix and are sensitive to non-standard model effects. In this review, we give a historical and theoretical introduction to penguins and a description of the various t

Luis A. Anchordoqui, Santiago E. Perez Bergliaffa, Marta L. Trobo, Graciela S. Birman

We present here three new solutions of Brans-Dicke theory for a stationary geometry with cylindrical symmetry in the presence of matter in rigid rotation with $T^μ_μ\neq 0$. All the solutions have eternal closed timelike curves in some region of the spacetime, the size of which depends on $ω$. Moreover, two of them do not go over a solution of general relati

D. v. Albada, W. v. Amersfoort, H. Boer Rookhuizen, J. Flokstra

A cryogenic spherical and omni-directional resonant-mass detector proposed by the GRAIL collaboration is described.

J. L. Hernandez-Pastora, J. Martin, E. Ruiz

The FHP algorithm allows to obtain the relativistic multipole moments of a vacuum stationary axisymmetric solution in terms of coefficients which appear in the expansion of its Ernst&#39;s potential on the symmetry axis. First of all, we will use this result in order to determine, at a certain approximation degree, the Ernst&#39;s potential on the symmetry a

Maurice H. P. M. van Putten

The small or zero cosmological constant, $Λ$, probably results from a macroscopic cancellation mechanism of the zero-point energies. However, nearby horizon surfaces any macroscopic mechanism is expected to result in imperfect cancellations. A phenomenological description is given for the residual variable cosmological constant. In the static, spherically sy

N. Read

A theory for a Fermi-liquid-like state in a system of charged bosons at filling factor one is developed, working in the lowest Landau level. The approach is based on a representation of the problem as fermions with a system of constraints, introduced by Pasquier and Haldane (unpublished). This makes the system a gauge theory with gauge algebra W_infty. The l

Y. S. Lee, M. Greven, B. O. Wells, R. J. Birgeneau

We report a neutron scattering study of the instantaneous spin correlations in the two-dimensional spin S=5/2 square-lattice Heisenberg antiferromagnet Rb_2MnF_4. The measured correlation lengths are quantitatively described, with no adjustable parameters, by high-temperature series expansion results and by a theory based on the quantum self-consistent harmo

Alexander N. Korotkov, V. I. Safarov

Single-electron transistor with ferromagnetic outer electrodes and nonmagnetic island is studied theoretically. Nonequilibrium electron spin distribution in the island is caused by tunneling current. The dependencies of the magnetoresistance ratio $δ$ on the bias and gate voltages show the dips which are directly related to the induced separation of Fermi le

Matteo Campellone, Barbara Coluzzi, Giorgio Parisi

In this work we study numerically a short range p-spin glass model in three dimensions. The behaviour of the model appears to be remarkably different from mean field predictions. In fact it shares some features typical of models with full replica-symmetry breaking (FRSB). Nevertheless, we believe that the transition that we study is intrinsically different f

S. Rombouts, K. Heyde, N. Jachowicz

A scheme is presented to decompose the exponential of a two-body operator in a discrete sum over exponentials of one-body operators. This discrete decomposition can be used instead of the Hubbard-Stratonovich transformation in auxiliary-field quantum Monte-Carlo methods. As an illustration, the decomposition is applied to the Hubbard model, where it is equiv

Hernan Larralde, Francois Leyvraz, Gustavo Martinez-Mekler, Raul Rechtman

We perform numerical scattering experiments on a Lorentz array of disks centered on a triangular lattice with L columns and study its transmission and reflection properties. In the finite horizon case, the motion of the particles may be modeled as simple one dimensional random walks with absorbing walls for which the scaling of the transmission and reflectio

S. L. A. de Queiroz, R. B. Stinchcombe

We introduce a new approach to connectivity-dependent properties of diluted systems, which is based on the transfer-matrix formulation of the percolation problem. It simultaneously incorporates the connective properties reflected in non-zero matrix elements and allows one to use standard random-matrix multiplication techniques. Thus it is possible to investi

K. H. Kim, J. H. Jung, D. J. Eom, T. W. Noh

Optical conductivity spectra of La_{0.7-y}Pr_{y}Ca_{0.3}MnO_3 were systematically investigated. For metallic samples, the spectral weight below 0.5 eV, whose magnitude can be represented by the effective carrier number N_{eff}(0.5 eV), increases as temperature becomes lower. Regardless of the Pr doping, all the measured values of N_{eff}(0.5 eV)/T_C fall int

S. Kronmueller, W. Dietsche, J. Weis, K. v. Klitzing

The magneto resistance of a narrow single quantum well is spectacularly different from the usual behavior. At filling factors 2/3 and 3/5 we observe large and sharp maxima in the longitudinal resistance instead of the expected minima. The peak value of the resistance exceeds those of the surrounding magnetic field regions by a factor of up to three. The form

Parongama Sen, Somendra M. Bhattacharjee

The probability distribution for the number of top to bottom spanning clusters in Directed percolation in two and three dimensions appears to be universal and is of the form $P(n) \sim \exp(-αn^2)$. We argue that $α$ is a new critical quantity vanishing at the upper critical dimension. The probability distribution of the individual masses of the spanning clu

Daniel Duffy, Stephan Haas, Eugene Kim

The Hubbard Hamiltonian on a two-leg ladder is studied numerically using quantum Monte Carlo and Exact Diagonalization techniques. A rung interaction, $V$, is turned on such that the resulting model has an exact SO(5) symmetry when $V=-U$. The evolution of the low energy excitation spectrum is presented from the pure Hubbard ladder to the SO(5) ladder. It is

P. T. Coleridge, A. S. Sachrajda, P. Zawadzki, R. L. Williams

No abstract available.

I. Hubeny, V. Hubeny

We have calculated several representative models of vertical structure of an accretion disk around a supermassive Kerr black hole. The interaction of radiation and matter is treated self-consistently, taking into account departures from LTE for calculating both the disk structure and the radiation field. The structural equations are described in detail, and

D. Barrado y Navascues, J. R. Stauffer, S. Randich

Randich and Schmitt [1995, A&A 298, 115] found that the coronal activity of solar-type and low mass stars in Praesepe is significantly lower than that of stars in the Hyades cluster. We have carried out several tests in order to find a possible explanation for this result. We have measured radial velocities of two groups of Praesepe stars (a dF-dK sample and

L. M. Lubin, M. Postman, J. B. Oke, K. U. Ratnatunga

We present a detailed morphological analysis of the galaxy populations in the first two clusters to be completed in an extensive observational study of nine high-redshift clusters of galaxies (Oke, Postman & Lubin 1998). These two clusters, CL0023+0423 and CL1604+4304, are at redshifts of z = 0.84 and z = 0.90, respectively. The morphological studies are bas

S. Zaroubi, G. Squires, Y. Hoffman, J. Silk

We consider a general method of deprojecting 2D images to reconstruct the 3D structure of the projected object, assuming axial symmetry. The method consists of the application of the Fourier Slice Theorem to the general case where the axis of symmetry is not necessarily perpendicular to the line of sight, and is based on an extrapolation of the image Fourier