April 1999 arXiv papers — page 16

Dong Lai

The inner region of the accretion disk onto a rotating magnetized central star (neutron star, white dwarf or T Tauri star) is subjected to magnetic torques which induce warping and precession of the disk. The origin of these torques lies in the interaction between the (induced) surface current on the disk and the horizontal magnetic field (parallel to the di

A. M. F. Rivas, A. M. Ozorio de Almeida

We construct reflection and translation operators on the Hilbert space corresponding to the torus by projecting them from the plane. These operators are shown to have the same group properties as their analogue on the plane. The decomposition of operators in the basis of reflections corresponds to the Weyl or center representation, conjugate to the chord rep

Joel M. Williams

Avogadro's number is a count of a definite number of things and, therefore, must be an integer and not a floating point number. Arguments are given herein that this integer should be precisely 2E79 - that is, N_o = 2E79 = 6.04 462 909 107 318 607 353 088 E23; hence, the binary mole.

M. K. Gaidarov, K. A. Pavlova, S. S. Dimitrova, M. V. Stoitsov

Single-particle overlap functions and spectroscopic factors are calculated on the basis of the one-body density matrices (ODM) obtained for the nucleus $^{16}O$ employing different approaches to account for the effects of correlations. The calculations use the relationship between the overlap functions related to bound states of the (A-1)-particle system and

Hiroshi Goda, Mikami Hirasawa, Ryosuke Yamamoto

Let $L$ be an oriented link with an alternating diagram $D$. It is known that $L$ is a fibered link if and only if the surface $R$ obtained by applying Seifert's algorithm to $D$ is a Hopf plumbing. Here, we call $R$ a Hopf plumbing if $R$ is obtained by successively plumbing finite number of Hopf bands to a disk. In this paper, we discuss its extension

A. Mutlu, T. Porter

Following Ellis, we investigate the notion of totally free crossed squares and related square complexes. It is shown how to interpret the information in a free simplicial group given with a choice of CW-basis, in terms of the data for a totally free crossed square. Results of Ellis then apply to give a description in terms of tensor products of crossed modul

A Mutlu, T Porter

In this paper, we examine the relationship between a CW-basis for a free simplicial group and methods of freely generating the corresponding crossed complex. Attention is concentrated on the case of resolutions, thus comparing free simplicial resolutions with crossed resolutions of a group.

P. J. Ehlers, T. Porter

We introduce a notion of join for (augmented) simplicial sets generalising the classical join of geometric simplicial complexes. The definition comes naturally from the ordinal sum on the base simplicial category $Δ$.

A Mutlu, T Porter

We introduce a pairing structure within the Moore complex NG of a simplicial group G and use it to investigate generators for NG_n\cap D_n where D_n is the subgroup generated by degenerate elements. This is applied to the study of algebraic models for homotopy types.

V. D. Ivashchuk, V. N. Melnikov

Multidimensional model describing the cosmological evolution of n Einstein spaces in the theory with l scalar fields and forms is considered. When electro-magnetic composite p-brane ansatz is adopted, and certain restrictions on the parameters of the model are imposed, the dynamics of the model near the singularity is reduced to a billiard on the (N-1)-dimen

A. G. M. Pickering, P. C. West

By solving the Ward identities in a superconformal field theory we find the unique three-point Green's functions composed of chiral superfields for N = 1,2,3,4 supersymmetry. We show that the N=1 four-point function with R-charge equal to one is uniquely determined by the Ward identities up to the specification of four constants. We discuss why chiral Gr

C. Armendariz-Picon, T. Damour, V. Mukhanov

It is shown that a large class of higher-order (i.e. non-quadratic) scalar kinetic terms can, without the help of potential terms, drive an inflationary evolution starting from rather generic initial conditions. In many models, this kinetically driven inflation (or "k-inflation" for short) rolls slowly from a high-curvature initial phase, down to a l

Roberto Balbinot, Alessandro Fabbri, Ilya Shapiro

The quantum stress tensor in the Unruh state for a conformal scalar propagating in a 4D Schwarzschild black hole spacetime is reconstructed in its leading behaviour at infinity and near the horizon by means of an effective action derived by functionally integrating the trace anomaly.

Jan de Boer, Andrea Pasquinucci, Kostas Skenderis

We study the duality between string theory on AdS_3 X S^3 X S^3 and two-dimensional conformal theories with large N=4 superconformal algebra A_gamma. We discuss configurations of intersecting branes which give rise to such near-horizon geometries. We compute the Kaluza-Klein spectrum and propose that the boundary superconformal theory can be described by a s

D. Drechsel, M. Gorchtein, B. Pasquini, M. Vanderhaeghen

We present fixed-$t$ subtracted dispersion relations for Compton scattering off the nucleon at energies $E_γ\leq$ 500 MeV, as a formalism to extract the nucleon polarizabilities with a minimum of model dependence. The subtracted dispersion integrals are mainly saturated by $πN$ intermediate states in the $s$-channel $γN \to πN \to γN$ and $ππ$ intermediate s

A. Djouadi, W. Kilian, M. Muhlleitner, P. M. Zerwas

The reconstruction of the Higgs potential in the Standard Model or supersymmetric theories demands the measurement of the trilinear Higgs couplings. These couplings affect the multiple production of Higgs bosons at high energy colliders. We present a systematic overview of the cross sections for the production of pairs of (light) neutral Higgs bosons at the

Walter Grimus, Subhendra Mohanty, Peter Stockinger

We consider a neutrino source at rest and discuss a condition for the existence of neutrino oscillations which derives from the finite lifetime $τ_S$ of the neutrino source particle. This condition is present if the neutrino source is a free particle such that its wave function is non-stationary. For a Gaussian wave function and with some simplifying assumpt

Seungwon Baek, Pyungwon Ko

We consider effects of CP violating phases in μand A_t parameters in the effective supersymmetric standard model on B\to X_s l^+ l^- and ε_K. Scanning over the MSSM parameter space with experimental constraints including edm constraints from Chang-Keung-Pilaftsis (CKP) mechanism, we find that the Br(B\to X_s l^+ l^-) can be enhanced by upto \sim 85 % compare

R. Barate

The cross sections and forward-backward asymmetries of hadronic and leptonic events produced in e+e- collisions at centre-of-mass energies of 130-183 GeV are presented. Results for ee, mumu, tautau, qq, bb and cc production show no significant deviation from the Standard Model predictions. This enable constraints to be set upon physics beyond the Standard Mo

R. Parentani

The aim of this letter is to clarify the relationships between Hawking radiation and the scattering of light by matter falling into a black hole. To this end we analyze the S-matrix elements of a model composed of a massive infalling particle (described by a quantized field) and the radiation field. These fields are coupled by current-current interactions an

Jaroslav Fabian, S. Das Sarma

Spin-flip Eliashberg function $α_S^2F$ and temperature-dependent spin relaxation time $T_1(T)$ are calculated for aluminum using realistic pseudopotentials. The spin-flip electron-phonon coupling constant $λ_S$ is found to be $2.5\times 10^{-5}$. The calculations agree with experiments validating the Elliott-Yafet theory and the spin-hot-spot picture of spin

Giovani L. Vasconcelos, J. J. P. Veerman

A simple geometrical model is presented for the gravity-driven motion of a single particle on a rough inclined surface. Adopting a simple restitution law for the collisions between the particle and the surface, we arrive at a model in which the dynamics is described by a one-dimensional map. This map is studied in detail and it is shown to exhibit several dy

A. P. Kharel, Anton V. Velichko, J. R. Powell, A. Porch

Striking features have been found in the nonlinear microwave (8 GHz) surface impedance $Z_s=R_s + jX_s$ of high-quality YBaCuO thin films with comparable low power characteristics [$R_{res}\sim 35--60 μΩ$ and $λ_L(15 K)\sim 130--260 nm$]. The surface resistance $R_s$ is found to increase, decrease, or remain independent of the microwave field $H_{rf}$ (up to

C. Bizon, M. D. Shattuck, J. B. Swift, Harry L. Swinney

Simulations of volumetrically forced granular media in two dimensions produce s tates with nearly homogeneous density. In these states, long-range velocity correlations with a characteristic vortex structure develop; given sufficient time, the correlations fill the entire simulated area. These velocity correlations reduce the rate and violence of collisions,

Yan Levin

We explore the equilibrium properties of a system composed of dipolar hard spheres. A new theory based on the ideas derived from the work of Debye and Hückel, Bjerrum, and Onsager is proposed to explain the absence of the anticipated critical point in this system.

C. Bizon, M. D. Shattuck, J. B. Swift, Harry L. Swinney

Under many conditions, macroscopic grains flow like a fluid; kinetic theory pred icts continuum equations of motion for this granular fluid. In order to test the theory, we perform event driven molecular simulations of a two-dimensional gas of inelastic hard disks, driven by contact with a heat bath. Even for strong dissipation, high densities, and small num

F. C. Alcaraz, R. Z. Bariev

A generalization of the simple exclusion asymmetric model is introduced. In this model an arbitrary mixture of molecules with distinct sizes $s = 0,1,2,...$, in units of lattice space, diffuses asymmetrically on the lattice. A related surface growth model is also presented. Variations of the distribution of molecules's sizes may change the excluded volum

F. C. Alcaraz, R. Z. Bariev

The exact solution is obtained for the eigenvalues and eigenvectors for two models of strongly correlated particles with single-particle correlated and uncorrelated pair hoppings. The asymptotic behavior of correlation functions are analysed in different regions, where the models exhibit different physical behavior.

Matteo Beccaria

For a class of generalized Hubbard models, we determine the maximal stability region for the superconducting eta-pairing ground state. We exploit the Optimized Ground State (OGS) approach and the Lanczos diagonalization procedure to derive a sequence of improved bounds. We show that some pieces of the stability boundary are asymptotic, namely independent on

L. Angelani, G. Parisi, G. Ruocco, G. Viliani

We analyze the properties of a Lennard-Jones system at the level of the potential energy landscape. After an exhaustive investigation of the topological features of the landscape of the systems, obtained studying small size sample, we describe the dynamics of the systems in the multi-dimensional configurational space by a simple model. This consider the conf

B. Noheda, J. A. Gonzalo, M. Hagen

Pulsed neutron diffraction investigations have been performed in the ferroelectric PZT system, Pb(Zr1-xTix)O3, doped with 1%wt. of Nb2O5, as a function of both temperature and composition. The study has been made in a wide range of temperatures encompassing the three known phases in Zr-rich PZT: ferroelectric low temperature (R3c), ferroelectric high tempera

David C. Brydges, Ph. A. Martin

Results on the correlations of low density classical and quantum Coulomb systems at equilibrium in three dimensions are reviewed. The exponential decay of particle correlations in the classical Coulomb system -- Debye-Hückel screening -- is compared and contrasted with the quantum case where strong arguments are presented for the absence of exponential scree

Sudhir R. Jain, Avinash Khare

For N impenetrable particles in one dimension where only the nearest and next-to-nearest neighbours interact, we obtain the complete spectrum both on a line and on a circle. Further, we establish a mapping between these N-body problems and the short-range Dyson model introduced recently to model intermediate spectral statistics in some systems using which we

Xi Dai, Yue Yu, Tao Xiang, Zhao-bin Su

The pseudogap effect of underdoped high-$T_c$ superconductors is studied in the U(1) gauge theory of the t-J model including the spinon pairing fluctuation. The gauge fluctuation breaks the long range correlation between the spinon pairs. The pairing fluctuation, however, suppresses significantly the low-lying gauge fluctuations and leads to a stable but pha

Xiao-Gang Wen

This paper has been withdrawn by the author.

S. Wakimoto, K. Yamada, S. Ueki, G. Shirane

Recent neutron-scattering experiments on La(2-x)Sr(x)CuO4 single crystals by Wakimoto et al. have revealed that elastic magnetic peaks appear at low temperatures in both insulating (x=0.02-0.05) and superconducting (x=0.06) samples. We have carried out further investigations particularly on the elastic incommensurate peaks for x=0.06, and found that the inte

D. G. Sterling, H. R. Dullin, J. D. Meiss

Chaotic dynamics can be effectively studied by continuation from an anti-integrable limit. We use this limit to assign global symbols to orbits and use continuation from the limit to study their bifurcations. We find a bound on the parameter range for which the Henon map exhibits a complete binary horseshoe as well as a subshift of finite type. We classify h

Mitrajit Dutta, Helena E. Nusse, Edward Ott, James A. Yorke

There exists a variety of physically interesting situations described by continuous maps that are nondifferentiable on some surface in phase space. Such systems exhibit novel types of bifurcations in which multiple coexisting attractors can be created simultaneously. The striking feature of these bifurcations is that they lead to fundamentally unpredictable

Alessandro Drago

The transition to quark matter can take place in neutron stars. The structure of a hybrid star, containing a core made of quark matter is discussed. The maximum mass of the non-rotating hybrid star turns out to be 1.6 M_s. Possible signatures of the quark phase as pulsar's timing, cooling rate etc. are briefly analyzed. The deconfinement transition can a

Joern Wilms, Michael Nowak, James B. Dove, Robert P. Fender

We discuss a series of observations of the black hole candidate GX 339-4 in low luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets and eight separate Rossi X-ray Timing Explorer (RXTE) data sets. Three of the RXTE observations were strictly simultaneou

C. L. Fryer, S. E. Woosley, D. H. Hartmann

While many models have been proposed for GRBs, those currently favored are all based upon the formation of and/or rapid accretion into stellar mass black holes. We present population synthesis calculations of these models using a Monte Carlo approach in which the many uncertain parameters intrinsic to such calculations are varied. We estimate the event rate

Hugo Martel, Paul R. Shapiro

When density fluctuations collapse gravitationally out of the expanding cosmological background universe to form galaxies, the secondary energy release which results can affect their subsequent evolution profoundly. We focus here on the effects of one form of such energy release - explosions, such as might result from the supernovae which end the lives of th

Luca Amendola

A class of generalized non-minimal coupling theories is investigated, in search of scaling attractors able to provide an accelerated expansion at the present time. Solutions are found in the strong coupling regime and when the coupling function and the potential verify a simple relation. In such cases, which include power law and exponential functions, the d

Amnon Stupp

We investigated wave amplification through the Electron-Cyclotron-Maser mechanism. We calculated absorption and emission coefficients without any approximations, also taking into account absorption by the ambient thermal plasma. A power-law energy distribution for the fast electrons was used, as is indicated by X-ray and microwave observations. We developed

Wolfram Freudling, Idit Zehavi, Luiz N. da Costa, Avishai Dekel

We estimate the power spectrum of mass density fluctuations from peculiar velocities of galaxies by applying an improved maximum-likelihood technique to the new all-sky SFI catalog. Parametric models are used for the power spectrum and the errors, and the free parameters are determined by assuming Gaussian velocity fields and errors and maximizing the probab

Michael R. Garcia, Paul J. Callanan

We report on x-ray observations of two soft x-ray transients containing neutron stars, 4U 2129+47 and EXO 0748-676. Our emphasis is on the quiescent properties of these sources. The x-ray spectrum and lightcurve of the eclipsing Low-Mass X-ray Binary (LMXB) 4U 2129+47 was measured with the ROSAT PSPC during its current quiescent state. The quiescent x-ray lu

John D. Barrow, Chris O'Toole

We show that observational limits on the possible time variation of constants of Nature are significantly affected by allowing for both space and time variation. Bekenstein's generalisation of Maxwell's equations to allow for cosmological variation of $alpha$ is investigated in a universe containing spherically symmetric inhomogeneities. The time var

Scott J. Kenyon, Jane X. Luu

We describe new planetesimal accretion calculations in the Kuiper Belt that include fragmentation and velocity evolution. All models produce two power law cumulative size distributions, N_C propto r^{-q}, with q = 2.5 for radii less than 0.3-3 km and q = 3 for radii exceeding 1-3 km. The power law indices are nearly independent of the initial mass in the ann

Matthew D. Lehnert, Wil J. M. van Breugel, Timothy M. Heckman, George K. Miley

We present rest-frame UV and Ly-alpha images of spatially-resolved structures around five high-redshift radio-loud quasars obtained with the WFPC2 camera on the Hubble Space Telescope. We find that all five quasars are extended and this "fuzz" contains ~5-40% of the total continuum flux and 15-65% of the Ly-alpha flux within a radius of about 1.5 arc

Boudewijn F. Roukema

Is the Universe (a spatial section thereof) finite or infinite? Knowing the global geometry of a Friedmann-Lema\^ıtre (FL) universe requires knowing both its curvature and its topology. A flat or hyperbolic (``open'') FL universe is {\em not} necessarily infinite in volume. Multiply connected flat and hyperbolic models are, in general, as consistent

Dong Lai, Richard Lovelace, Ira Wasserman

It has recently been suggested that the maximum observed quasi-periodic oscillation (QPO) frequencies, $ν_{max}$, for several low-mass X-ray binaries, particularly 4U 1820-30, correspond to the orbital frequency at the inner-most stable orbit of the accretion disk. This would imply that the neutron stars in these systems have masses $\go 2~M_\odot$, consider

Peter Nisenson, Costas Papaliolios

Speckle interferometry observations, made just 30 and 38 days after the explosion of supernova SN1987A (SN) (which was first seen on February 23, 1987), showed evidence for a bright source, separated from the SN by only 60 mas. Reprocessing of that data using new image reconstruction algorithms has resulted in much cleaner images which not only clearly show

Marc Kamionkowski, Arthur Kosowsky

In forthcoming years, connections between cosmology and particle physics will be made increasingly important with the advent of a new generation of cosmic microwave background (CMB) experiments. Here, we review a number of these links. Our primary focus is on new CMB tests of inflation. We explain how the inflationary predictions for the geometry of the Univ

Benedetta Ciardi, Andrea Ferrara, Tom Abel

We study the effects of the ionizing and dissociating photons produced by PopIII objects on the surrounding intergalactic medium. We find that the typical size of a H_2 photodissociated region, R_d ~ 1-5 kpc, is smaller than the mean distance between sources at z ~ 20-30, but larger than the ionized region by a factor depending on the detailed properties of

K. T. Matchev, D. M. Pierce

We determine the Tevatron's reach in supersymmetric parameter space in trilepton, like-sign dilepton, and two lepton one tau-jet channels. We critically study the standard model background processes. We find larger backgrounds and, hence, significantly smaller reach regions than recent analyses. We identify the major cause of the background discrepancy.

Jorge Alberto Calvo

The space of n-sided polygons embedded in three-space consists of a smooth manifold in which points correspond to piecewise linear or ``geometric'' knots, while paths correspond to isotopies which preserve the geometric structure of these knots. The topology of these spaces for the case n = 6 and n = 7 is described. In both of these cases, each knot space co

G. Aldazabal, D. Badagnani, L. E. Ibanez, A. M. Uranga

It is often stated in the literature concerning D=4,6 compact Type IIB orientifolds that tadpole cancellation conditions i) uniquely fix the gauge group (up to Wilson lines and/or moving of branes) and ii) are equivalent to gauge anomaly cancellation. We study the relationship between tadpole and anomaly cancellation conditions and qualify both statements. I

Jon P. Fulbright, Robert P. Kraft

Recent LTE analyses (Israelian et al. 1998 and Bosegaard et al. 1999) of the OH bands in the optical-ultraviolet spectra of nearby metal-poor subdwarfs indicate that oxygen abundances are generally higher than those previously determined. The difference increases with decreasing metallicity and reaches delta([O/Fe]) ~ +0.6 dex as [Fe/H] approaches -3.0. Empl

A. J. M. Medved, G. Kunstatter

We consider one-loop quantum corrections to the thermodynamics of a black hole in generic 2-dimensional dilaton gravity. The classical action is the most general diffeomorphism invariant action in 1+1 space-time dimensions that contains a metric, dilaton, and Abelian gauge field, and having at most second derivatives of the fields. Quantum corrections are in

John Ellis, Smaragda Lola

We reconsider the possibility that the masses of the three light neutrinos of the Standard Model might be almost degenerate and close to the present upper limits from Tritium beta decay and cosmology. In such a scenario, the cancellations required by the latest upper limit on neutrinoless double-beta decay enforce near-maximal mixing that may be compatible o

Stanley J. Brodsky, Johan Rathsman, Carlos Merino

We show that the asymmetry in the fractional energy of charm versus anticharm jets produced in high energy diffractive photoproduction is sensitive to the interference of the Odderon $(C = -)$ and Pomeron $(C = +)$ exchange amplitudes in QCD. We predict the dynamical shape of the asymmetry in a simple model and estimate its magnitude to be of the order 15% u

Andri M. Gretarsson, Gregory M. Harry

For thermal noise considerations of LIGO suspensions, the sources of dissipation in the suspending fibers must be analyzed. To determine the dissipation induced by the surface of fused silica fibers, we measured the quality factor of fibers having various diameters. We measured a maximum quality factor of 21 million and extrapolated to obtain an intrinsic qu

A. Connolly

A search for long-lived charged massive particles in CDF's Run1b data sample is presented. The search looks for highly ionizing tracks which would result from slowly moving massive particles. We search for strongly produced particles using a stable color triplet quark as a reference model, and a separate search was performed for weakly produced particles usi

J-P. Gazeau, J. Renaud, M. V. Takook

We present in this paper a fully covariant quantization of the minimally-coupled massless field on de Sitter space. We thus obtain a formalism free of any infrared (e.g logarithmic) divergence. Our method is based on a rigorous group theoretical approach combined with a suitable adaptation (Krein spaces) of the Wightman-Gärding axiomatic for massless fields

Birger B. Back

Collisions of Au+Au have been studied at beam kinetic energies of 6, 8, and 10.8 GeV/nucleon at the AGS facility at Brookhaven National Laboratory. Particles emitted from the collisions were momentum analyzed and identified in a magnetic spectrometer system. Measurements were made at spectrometer angles in the range 14deg - 59deg. m_t spectra of protons from

Ralph Blumenhagen, Anamaria Font, Dieter Lust

We construct non-tachyonic, non-supersymmetric orientifolds of Type 0B strings in ten, six and four space-time dimensions. Typically, these models have unitary gauge groups with charged massless fermionic and bosonic matter fields. However, generically there remains an uncancelled dilaton tadpole.

Lawrence J. Hall, David Smith

In theories with large extra dimensions, constraints from cosmology lead to non-trivial lower bounds on the fundamental scale M_F, corresponding to upper bounds on the radii of the compact extra dimensions. These constraints are especially relevant to the case of two extra dimensions, since only if M_F is 10 TeV or less do deviations from the standard gravit

Tomoya Ono, Kikuji Hirose

We present a simple and efficient technique in ab initio electronic-structure calculation utilizing real-space double-grid with a high density of grid points in the vicinity of nuclei. This technique promises to greatly reduce the overhead for performing the integrals that involves non-local parts of pseudopotentials, with keeping a high degree of accuracy.

A. A. Penin, A. A. Pivovarov

We present an analytical description of top-antitop pair production near the threshold in $e^+e^-$ annihilation and $\g\g$ collisions. A set of basic observables considered includes the total cross sections, forward-backward asymmetry and top quark polarization. The threshold effects relevant for the basic observables are described by three universal functio

B. B. Back, D. J. Blumenthal, C. N. Davids, D. J. Henderson

The fusion evaporation-residue cross section for 32S+184W has been measured at beam energies of E_beam = 165, 174, 185, 196, 205, 215, 225, 236, 246,and 257 MeV using the ATLAS Fragment Mass Analyzer. The data are compared with Statistical Model calculations and it is found that a nuclear dissipation strength, which increases with excitation energy, is requi

Piet Claus, Kor Van Hoof, Antoine Van Proeyen

We present a formulation of the coupling of vector multiplets to N=2 supergravity which is symplectic covariant (and thus is not based on a prepotential) and uses superconformal tensor calculus. We do not start from an action, but from the combination of the generalised Bianchi identities of the vector multiplets in superspace, a symplectic definition of spe

R. Della Ceca, G. Castelli, V. Braito, I. Cagnoni

A complete sample of 60 serendipitous hard X-ray sources with flux in the range $\sim 1 \times 10^{-13}$ \ecs to $\sim 4 \times 10^{-12}$ \ecs (2 - 10 keV), detected in 87 ASCA GIS2 images, was recently presented in literature. Using this sample it was possible to extend the description of the 2-10 keV LogN(>S)-LogS down to a flux limit of $\sim 6\times 10^{

Y. Brihaye, B. Hartmann, J. Kunz, N. Tell

We study static spherically symmetric dyonic black holes in Einstein-Yang-Mills-Higgs theory. As for the magnetic non-abelian black holes, the domain of existence of the dyonic non-abelian black holes is limited with respect to the horizon radius and the dimensionless coupling constant $α$, which is proportional to the ratio of vector meson mass and Planck m

A. G. Bytsko

Characters and linear combinations of characters that admit a fermionic sum representation as well as a factorized form are considered for some minimal Virasoro models. As a consequence, various Rogers-Ramanujan type identities are obtained. Dilogarithm identities producing corresponding effective central charges and secondary effective central charges are d

S. Y. Choi, M. Guchait, H. S. Song, W. Y. Song

We have analyzed the supersymmetric tri-lepton signals for sparticle searches at the Tevatron in the minimal supersymmetric standard model with general CP phases without generational mixing. The CP phases may affect very strongly the chargino and neutralino mass spectrums and $σ(p\bar{p}\to\tildeχ^-_1\tildeχ^0_2)$ as well as ${\cal B}(\tildeχ^-_1\to\tildeχ^0

P. Singha Deo, J. P. Pekola, M. Manninen

We study the heat capacity of isolated giant vortex states, which are good angular momentum ($L$) states, in a mesoscopic superconducting disk using the Ginzburg-Landau (GL) theory. At small magnetic fields the $L$=0 state qualitatively behaves like the bulk sample characterized by a discontinuity in heat capacity at $T_c$. As the field is increased the disc

Ehud Perlsman, Shlomo Havlin

We study the relation between the directed polymer and the directed percolation models, for the case of a disordered energy landscape where the energies are taken from bimodal distribution. We find that at the critical concentration of the directed percolation, the directed polymer undergoes a transition from the directed polymer universality class to the di

G. Bonnet

In this letter, we show how one can solve easily the Potts-3 + branching interactions and Potts-\infty matrix models, by the means of the equations of motion (loop equations). We give an algebraic equation for the resolvents of these models, and their scaling behaviour. This shows that the equations of motion can be a useful tool for solving such models.

Chong Sheng Li, Xinmin Zhang, Shou Hua Zhu

We evaluate the contribution of SUSY-QCD to top-charm associated production at next generation linear colliders. Our results show that the production cross section of the process $e^+e^-\to t\bar c{or}\bar t c$ could be as large as 0.1 fb, which is larger than the prediction of the SM by a factor of $10^8$.

R. Aditi Simha, Sriram Ramaswamy

Starting from the time-dependent Ginzburg-Landau (TDGL) equations for a type II superconductor, we derive the equations of motion for the displacement field of a moving vortex lattice without inertia or pinning. We show that it is linearly stable and, surprisingly, that it supports wavelike long-wavelength excitations arising not from inertia or elasticity b

Y. S. Myung, H. W. Lee

We study the relationship between the gauge boson coupled to spin 2 operator and the singleton in three-dimensional anti-de Sitter space(AdS$_3$). The singleton can be expressed in terms of a pair of dipole ghost fields $A$ and $B$ which couple to $D$ and $C$ operators on the boundary of AdS$_3$. These operators form the logarithmic conformal field theory(LC

V. A. Sautenkov, M. D. Lukin, C. J. Bednar, G. R. Welch

We utilize the generation of large atomic coherence to enhance the resonant nonlinear magneto-optic effect by several orders of magnitude, thereby eliminating power broadening and improving the fundamental signal-to-noise ratio. A proof-of-principle experiment is carried out in a dense vapor of Rb atoms. Detailed numerical calculations are in good agreement

Ralf S. Klessen, Andreas Burkert

The isothermal dynamical evolution of a clumpy and turbulent molecular cloud region and its fragmentation into a protostellar cluster is investigated numerically. The effect of different initial density and velocity distributions, generated from different realizations of a Gaussian random field with power spectrum P(k) ~ k^{-2} is investigated. As a result o

I. V. Baryakhtar, V. G. Baryakhtar, E. N. Economou

We analyze the kinetic behavior of localized excitations - solitons, breathers and phonons - in Sine-Gordon model. Collision integrals for all type of localized excitation collision processes are constructed, and the kinetic equations are derived. We analyze the kinetic behavior of localized excitations - solitons, breathers and phonons - in Sine-Gordon mode

Richard J. Hughes, George L. Morgan, C. Glen Peterson

The secure distribution of the secret random bit sequences known as "key" material, is an essential precursor to their use for the encryption and decryption of confidential communications. Quantum cryptography is a new technique for secure key distribution with single-photon transmissions: Heisenberg's uncertainty principle ensures that an advers

Terry Rudolph

We discuss the physical nature of quantum information, in particular focussing on tasks that are achievable by some physical realizations of qubits but not by others.

Jean-Pierre Amiet, Stefan Weigert

Coherent states provide an appealing method to reconstruct efficiently a pure state of a quantum mechanical spin s. A Stern-Gerlach apparatus is used to measure (4s+1) expectations of projection operators on appropriate coherent states in the unknown state. These measurements are compatible with a finite number of states which can be distinguished, in the ge

I. Goidenko, L. Labzowsky, A. Nefiodov, G. Plunien

A calculation of the simplest part of the second-order electron self-energy (loop after loop irreducible contribution) for hydrogen-like ions with nuclear charge numbers $3 \leq Z \leq 92$ is presented. This serves as a test for the more complicated second-order self-energy parts (loop inside loop and crossed loop contributions) for heavy one-electron ions.

A. S. Zibrov, M. D. Lukin, M. O. Scully

We demonstrate an efficient nonlinear process in which Stokes and anti-Stokes components are generated spontaneously in a Raman-like, near resonant media driven by low power counter-propagating fields. Oscillation of this kind does not require optical cavity and can be viewed as a spontaneous formation of atomic coherence grating.

H. M. Wiseman

Using a feedback loop it is possible to reduce the fluctuations in one quadrature of an in-loop field without increasing the fluctuations in the other. This effect has been known for a long time, and has recently been called ``squashing'' [B.C. Buchler et al., Optics Letters {\bf 24}, 259 (1999)], as opposed to the ``squeezing'' of a free fie

E. Miyata, H. Tsunemi, H. Ogata, D. Akutsu

MAXI, Monitor of All-sky X-ray Image, is the X-ray observatory on the Japanese experimental module (JEM) Exposed Facility (EF) on the International Space Station (ISS). MAXI is a slit scanning camera which consists of two kinds of X-ray detectors: one is a one-dimensional position-sensitive proportional counter with a total area of $\sim 5000 cm^2$, the Gas

Raymond S. Mackintosh

The Debrecen workshop was one of a number held in preparation for the UNESCO-ICSU World Conference on Science, which will be held in Budapest, June 1999. A report representing the views of the workshop, prepared for that conference and containing a number of recommended actions, is included with this summary. The workshop affirmed the ongoing importance of p

A. G. Khachatryan, S. S. Elbakian

The effect of nonlinearity on plasma wake wave excited by a relativistic cylindrical charged bunch is investigated. It is shown that owing to the nonlinearity the amplitude of wake wave gets modulated in the longitudinal direction. The nonlinear wavelength in the excited field changes in the transverse direction with the result that the phase front is distor

H. Boos

The model which is the generalization of the one-dimensional XY-spin chain for the case of the two-dimensional square lattice is considered. The subspace of the ``string'' states is studied. The solution to the eigenvalue problem is obtained for the single ``string'' in cases of the ``string'' with fixed ends and ``string'' of

Olivier Debarre

For any positive integer $k$ and any integer $n$ large enough, we construct a Fano variety $X$ with Picard number $k$ and dimension $n$ such that $((-K_X)^n)^{1/n}$ grows like $n^k/(\log n)^{k-1}$.

Klaus Altmann, Duco van Straten

We prove a vanishing theorem for the Hodge number h^21 of projective toric varieties provided by a certain class of polytopes. We explain how this Hodge number also gives information about the deformation theory of the toric Gorenstein singularity derived from the same polytope. In particular, the vanishing theorem for h^21 implies that these deformations ar

Indranil Biswas, Leticia Brambila-Paz

Let $X$ be a compact connected Riemann surface of genus $g$, with $g\geq 2$, and ${\cal M}_ξ$ a smooth moduli space of fixed determinant semistable vector bundles of rank $n$, with $n\geq 2$, over $X$. Take a smooth anticanonical divisor $D$ on ${\cal M}_ξ$. So $D$ is a Calabi-Yau variety. We compute the number of moduli of $D$, namely $\dim H^1(D, T_D)$, to

Klaus Hulek, Fabrizio Catanese, Chris Peters, Miles Reid

This file, provided as bibliographical information, contains the table of contents and editors' foreword from the proceedings of the July 1996 Warwick EuroConference on Algebraic Geometry.

Tobias Ekholm

First order invariants of generic immersions of manifolds of dimension nm-1 into manifolds of dimension n(m+1)-1, m,n>1 are constructed using the geometry of self-intersections. The range of one of these invariants is related to Bernoulli numbers. As by-products some geometrically defined invariants of regular homotopy are found.

Justin R. David

We construct the anti-de Sitter supergravity in three dimensions associated with the supergroup $SU(1,1|2)\times SU(1,1|2)$. The field content and the action are inferred using the fact that $AdS$ supergravity theories in three dimensions are Chern-Simons theories.