January 2000 arXiv papers — page 20

Victor J. Emery, Eduardo Fradkin, Steven A. Kivelson, Tom C. Lubensky

We present a theory of the electron smectic fixed point of the stripe phases of doped layered Mott insulators. We show that in the presence of a spin gap three phases generally arise: (a) a smectic superconductor, (b) an insulating stripe crystal and (c) a smectic metal. The latter phase is a stable two-dimensional anisotropic non-Fermi liquid. In the abscen

N. Sasaki, O. Miyamura, S. Muroya, C. Nonaka

We evaluate thermodynamical quantities and transport coefficients of a dense and hot hadronic matter based on an event generator URASiMA (Ultra-Relativistic AA collision Simulator based on Multiple Scattering Algorithm). The statistical ensembles in equilibrium with fixed temperature and chemical potential are generated by imposing periodic boundary conditio

Guang-jiong Ni, Hong Guan, Weimin Zhou, Jun Yan

The original version of Einstein-Podolsky-Rosen (EPR) paradox and the Klein paradox of Klein-Gordon (KG) equation are discussed to show the necessity of existence of antiparticle with its wavefunction being fixed unambiguously. No concept of "hole" is needed.

S. Bottai, L. Perrone

A simulation package for the transport of high energy muons has been developed. It has been conceived to replace the muon propagation software modules implemented in the detector simulation program GEANT3. Here we discuss the results achieved with our package and we check the agreement with numerical calculations up to 10**8 GeV.

Steffen Wilke, Vincent Natoli, Morrel H. Cohen

In this report we present a theoretical investigation of the potential-energy diagram for water formation from adsorbed O and H species on Rh(111) and Pt(111) surfaces. The study is based on accurate first-principles calculations applying density-functional theory. Our results are compared to the potential-energy diagram for this reaction inferred from exper

W. Saunders, W. J. Sutherland, S. J. Maddox, O. Keeble

We present the catalogue, mask, redshift data and selection function for the PSCz survey of 15411 IRAS galaxies across 84% of the sky. Most of the IRAS data is taken from the Point Source Catalog, but this has been supplemented and corrected in various ways to improve the completeness and uniformity. We quantify the known imperfections in the catalogue, and

W. M. Alberico, G. Garbarino

By employing recent data on non-mesonic decay of s-shell Lambda-hypernuclei we study, within the phenomenological model of Block and Dalitz, the validity of the Delta I=1/2 rule in the Lambda N--> NN process. Due to the low experimental precision, a possible violation of this rule can be neither proved nor excluded at present with sufficient accuracy: a pure

Michael T. Anderson

A complete characterization is obtained of the asymptotic behavior of solutions of the static vacuum Einstein equations which have a (pseudo)-compact horizon or boundary and are complete away from the boundary. It is proved that the time-symmetric space-like hypersurface has only finitely many ends, each of which is either asymptotically flat (AF) or parabol

K. I. Bolotin, M. A. Vasiliev

Generic solution of free equations for massless fields of an arbitrary spin in $AdS_4$ is built in terms of the star-product algebra with spinor generating elements. A class of "plane wave" solutions is described explicitly.

Haye Hinrichsen

This review addresses recent developments in nonequilibrium statistical physics. Focusing on phase transitions from fluctuating phases into absorbing states, the universality class of directed percolation is investigated in detail. The survey gives a general introduction to various lattice models of directed percolation and studies their scaling properties,

Xiao-Jun Bi, Yuan-Ben Dai, Xiao-Yuan Qi

We calculate the large Yukawa coupling corrections to the top and bottom scalar quark pair production in $\ee$ annihilation within the Minimal Supersymmetric Standard Model. We include the vertex corrections and the corrections to the gauge boson propagator enhanced by large masses. We find the total corrections are quite significant. In some regions of the

Kouji Nakamura, Akihiro Ishibashi, Hideki Ishihara

We study the perturbative dynamics of an infinite gravitating Nambu-Goto string within the general-relativistic perturbation framework. We develop the gauge invariant metric perturbation on a spacetime containing a self-gravitating straight string with a finite thickness and solve the linearized Einstein equation. In the thin string case, we show that the st

A. G. Ramm

The inverse problem of finding the refraction coefficient of a shallow ocean from the observation of the extra Cauchy data for the acoustic field at the surface of the ocean is studied. Uniqueness theorem is proved and a reconstruction algorithm is obtained. Comments are given on the related results in the literature.

Alessandra Buonanno, Thibault Damour

Combining recent techniques giving non-perturbative re-summed estimates of the damping and conservative parts of the two-body dynamics, we describe the transition between the adiabatic phase and the plunge, in coalescing binary black holes with comparable masses moving on quasi-circular orbits. We give initial dynamical data for numerical relativity investig

Toshihiko Ono

This paper proves that protomechanics, previously introduced in quant-ph/9909025, deduces both quantum mechanics and classical mechanics. It does not only solve the problem of the arbitrariness on the operator ordering for the quantization procedure, but also that of the analyticity at the exact classical-limit of $\hbar =0 $. In addition, proto-mechanics pr

Arthur O. Pittenger, Morton H. Rubin

Using the finite Fourier transform, we introduce a generalization of Pauli-spin matrices for $d$-dimensional spaces, and the resulting set of unitary matrices $S(d) $ is a basis for $d\times d$ matrices. If $N=d_{1}\times d_{2}\times...\times d_{b}$ and $H^{[ N]}=\bigotimes H^{% [ d_{k}]}$, we give a sufficient condition for separability of a density matrix

N. Nayak, A. S. Majumdar, V. Bartzis

We consider a micromaser model to study the influence of Dicke superradiance in the context of the one-atom maser. The model involves a microwave cavity into which two-level Rydberg atoms are pumped in pairs. We consider a random pump mechanism which allows the presence of at most one pair of atoms in the cavity at any time. We analyze the differences betwee

Gerd van de Sand, Jan M Rost

We present a semiclassical S-matrix study of inelastic collinear electron-hydrogen scattering. A simple way to extract all necessary information from the deflection function alone without having to compute the stability matrix is described. This includes the determination of the relevant Maslov indices. Results of singlet and triplet cross sections for excit

Robert M. Kerr, Axel Brandenburg

Analysis using new calculations with 3 times the resolution of the earlier linked magnetic flux tubes confirms the transition from singular to saturated growth rate reported by Grauer and Marliani \cite{GrauerMar99} for the incompressible cases is confirmed. However, all of the secondary tests point to a transition back to stronger growth rate at a different

R. Rapp, J. Wambach

Theoretical approaches to assess modifications of vector mesons in the medium, as well as their experimental identification via electromagnetic probes, are discussed. Implications for the nature of chiral symmetry restoration in hot/dense matter are outlined and put into context with the axialvector channel.

W. Cassing

The nuclear equation of state (EoS) is investigated by flow phenomena in relativistic heavy-ion collisions, both in transverse and radial direction, in comparison to experimental data from 150 A MeV to 11 A GeV. To this aim the collective dynamics of the nucleus-nucleus collision is described within a transport model of the coupled channel RBUU type. There a

P. R. Huffman, C. R. Brome, J. S. Butterworth, K. J. Coakley

Accurate measurement of the lifetime of the neutron (which is unstable to beta decay) is important for understanding the weak nuclear force and the creation of matter during the Big Bang. Previous measurements of the neutron lifetime have mainly been limited by certain systematic errors; however, these could in principle be avoided by performing measurements

A. Abd-Elhafiez, M. M. Chernyavski, K. G. Gulamov, V. Sh. Navotny

Experimental data on multi-fragmentation of residual krypton nuclei created in the interactions of the krypton nuclei with photoemulsion nuclei at the energy of 0.9 GeV per nucleon are presented in a comparison with the analogous data on fragmentation of gold residual nuclei at the energy of 10.7 GeV/nucleon. It is shown for the first time that there are two

Luc Rey-Bellet, Lawrence E. Thomas

We consider a model of heat conduction which consists of a finite nonlinear chain coupled to two heat reservoirs at different temperatures. We study the low temperature asymptotic behavior of the invariant measure. We show that, in this limit, the invariant measure is characterized by a variational principle. We relate the heat flow to the variational princi

A. G. Ramm

An inverse problem of finding an obstacle and the boundary condition on its surface from the fixed-energy scattering data is studied. A new method is developed for a proof of the uniqueness results. The method does not use the discreteness of the spectrum of the corresponding Laplacian in a bounded domain. Proof of the uniqueness results is based on the fact

A. G. Ramm

The inverse problem of finding the velocity profile from the surface measurements of acoustic field is considered. The dimensionalities of the data and of the unknown velocity profile are equal, both are equal 3. Analytical explicit examples are given showing vast non-uniqueness of the solution to this inverse problem.

A. G. Ramm

It is proved that if the scattering amplitudes at a fixed wavenumber for two obstacles from a certain large class of obstacles differ a little, than the obstacles differ a little. Error estimate is given. It is proved that there is an inversion formula for finding the obstacle from a fixed-energy scattering data.

R. P. Thomas

Talk given at Harvard, January 1999, published in the Proceedings of the Harvard Winter School on mirror symmetry, vector bundles and lagrangian cycles, 1999, International Press. Surveys the joint work [ST, KS] with Paul Seidel and Mikhail Khovanov.

Vladimir Dergachev

In this paper we prove several theorems about the behavior of index of Lie algebras derived from associative algebras under tensor products of underlying associative algebras.

David M. J. Calderbank

Weyl derivatives, Weyl-Lie derivatives and conformal submersions are defined, then used to generalize the Jones-Tod correspondence between selfdual 4-manifolds with symmetry and Einstein-Weyl 3-manifolds with an abelian monopole. In this generalization, the conformal symmetry is replaced by a particular kind of conformal submersion with one dimensional fibre

Martin Schlichenmaier

Elements of a global operator approach to the WZNW models for compact Riemann surfaces of arbitrary genus g with N marked points were given by Schlichenmaier and Sheinman. This contribution reports on the results. The approach is based on the multi-point Krichever-Novikov algebras of global meromorphic functions and vector fields, and the global algebras of

Marshall A. Whittlesey

We say that a subset of C^n is hypoconvex if its complement is the union of complex hyperplanes. Let D be the closed unit disk in C, T the unit circle. We prove two conjectures of Helton and Marshall. (See ``Frequency domain design and analytic selections,'' Indiana Univ. Math. J. 39, no. 1 (1990), 157-184.) Let p:T X C^n --> R+ be a smooth function

Samik Sen, Siddhartha Sen, James C. Sexton, David H. Adams

We give a detailed general description of a recent geometrical discretisation scheme and illustrate, by explicit numerical calculation, the scheme's ability to capture topological features. The scheme is applied to the Abelian Chern-Simons theory and leads, after a necessary field doubling, to an expression for the discrete partition function in terms of

F. A. Cachazo, C. Vafa

We revisit the duality between type I' and heterotic strings in 9 dimensions. We resolve a puzzle about the validity of type I' perturbation theory and show that there are regions in moduli which are not within the reach of type I' perturbation theory. We find however, that all regions of moduli are described by a special class of real elliptic $

Domenico Seminara

We exploit the tree level bosonic 4-particle scattering amplitudes in D=11 supergravity to construct the bosonic part of a linearized supersymmetry-, coordinate- and gauge-invariant. By differentiation, this invariant can be promoted to be the natural lowest (two-loop) order counterterm. Its existence implies that the perturbative supersymmetry does not prot

Satoshi Iso, Hikaru Kawai, Yoshihisa Kitazawa

We propose a bi-local representation in noncommutative field theory. It provides a simple description for high momentum degrees of freedom. It also shows that the low momentum modes can be well approximated by ordinary local fields. Long range interactions are generated in the effective action for the lower momentum modes after integrating out the high momen

Allen C. Hirshfeld, Thomas Schwarzweller

We investigate the Poisson-Sigma model on the classical and quantum level. In the classical analysis we show how this model includes various known two-dimensional field theories. Then we perform the calculation of the path integral in a general gauge, and demonstrate that the derived partition function reduces to the familiar form in the case of 2d Yang-Mill

M. B. Voloshin

The weak decays Xi_b -> Lambda_b pi and Xi_c -> Lambda_c pi, in which the heavy quark is not destroyed, are discussed. The branching fractions for these decays, corresponding to an absolute rate of order 0.01 ps^{-1}, should be at a one percent level for the b hyperons and at a (few) per mill level for Xi_c, possibly making feasible their experimental study

Kenneth Lane, Tonguc Rador, Estia Eichten

We have carried out numerical studies of vacuum alignment in technicolor models of electroweak and flavor symmetry breaking. The goal is to understand alignment's implications for strong and weak CP nonconservation in quark interactions. In this first part, we restrict our attention to the technifermion sector of simple models. We find several interestin

Halina Abramowicz

Recent experimental results on inclusive diffractive scattering and on exclusive vector meson production are reviewed. The dynamical picture of hard diffraction emerging in perturbative QCD is highlighted.

S. Kumano

We discuss possible studies of parton distributions at the proposed 50-GeV PS facility. First, comments are given in general on the importance of large-x physics for finding new physics. Second, polarized deuteron reactions are discussed in connection with new structure functions which are specific for a spin-1 hadron. Third, if the polarized proton-deuteron

The WA102 Collaboration, D. Barberis

The production and decay properties of the f0(1370), f0(1500), f0(2000) and f2(1950) have been studied in central pp interactions at 450 GeV/c. The dPT, phi and |t| distributions of these resonances are presented. For the J = 0 states, the f0(1370) and f0(2000) have similar dPT and phi dependences. These are different to the dPT and phi dependences of the f0

T. Dereli, Yu. N. Obukhov

The solutions of the Einstein-Maxwell-Chern-Simons theory are studied in (1+2) dimensions with the self-duality condition imposed on the Maxwell field. We give a closed form of the general solution which is determined by a single function having the physical meaning of the quasilocal angular momentum of the solution. This function completely determines the g

Masafumi Seriu

We investigate the averaging problem in cosmology as the problem of introducing a distance between spaces. We first introduce the spectral distance, which is a measure of closeness between spaces defined in terms of the spectra of the Laplacian. Then we define a space S, the space of all spaces equipped with the spectral distance. We argue that this space S

Stefaan De Cnodder, Omar Elloumi, Kenny Pauwels

We consider the adaptation of random early detection (RED) as an active queue management algorithm for TCP traffic in Internet gateways where different maximum transfer units (MTUs) are used. We studied the two existing RED variants and point out a weakness in both. The first variant where the drop probability is independent from the packet size discriminate

Toshinao Akuzawa

The multiplicative Newton-like method developed by the author et al. is extended to the situation where the dynamics is restricted to the orthogonal group. A general framework is constructed without specifying the cost function. Though the restriction to the orthogonal groups makes the problem somewhat complicated, an explicit expression for the amount of in

Subir Sachdev, Oleg A. Starykh

We describe the different regimes of finite temperature dynamics in the vicinity of a zero temperature superconductor to insulator quantum phase transition in two dimensions. New results are obtained for a low temperature phase-only hydrodynamics, and for the intermediate temperature quantum-critical region. In the latter case, we obtain a universal relation

E. Barkai

The fractional Fokker-Planck equation (FFPE) [R. Metzler, E. Barkai, J. Klafter, Phys. Rev. Lett., 82, 3563 (1999)] describes an anomalous sub diffusive behavior of a particle in an external force field. In this paper we present the solution of the FFPE in terms of an integral transformation. The transformation maps the solution of ordinary Fokker-Planck equ

T. Bergeman, D. L. Feder, N. L. Balazs, B. I. Schneider

The mean-field properties of finite-temperature Bose-Einstein gases confined in spherically symmetric harmonic traps are surveyed numerically. The solutions of the Gross-Pitaevskii (GP) and Hartree-Fock-Bogoliubov (HFB) equations for the condensate and low-lying quasiparticle excitations are calculated self-consistently using the discrete variable representa

Chia-Ying Liu, D. E. MacLaughlin, H. G. Lukefahr, G. Miller

Non-Fermi-liquid (NFL) behavior in the f-sublattice-diluted alloy system U_{1-x}Th_xPd_2Al_3 has been studied using ^{27}Al nuclear magnetic resonance (NMR). Impurity satellites due to specific U near-neighbor configurations to ^{27}Al sites are clearly resolved in both random and field-aligned powder samples. The spatial mean Kbar and rms spread delta K of

K. Ziegler

A grand canonical system of hard-core bosons, subject to thermal fluctuations, is studied on a lattice. Starting from the slave-boson representation with fields for occupied and unoccupied sites, an effective field theory is derived in which a complex field corresponds with the order parameter of the condensate and a real field with the total density of boso

Shi-Liang Zhu, Z. D. Wang, Yong-Dong Zhang

We derive a formula of the nonadiabatic noncyclic Pancharatnam phase for a quantum spin-1/2 particle subject to an arbitrary magnetic field. The formula is applied to three specific kinds of magneic fields. (i) For an orientated magnetic field, the Pancharatnam phase is derived exactly. (ii) For a rotating magnetic field, the evolution equation is solved ana

P. Azaria, P. Lecheminant

We study a one-dimensional electron gas in a special antiferromagnetic environment made by two spin-1/2 Heisenberg chains and the one-dimensional two-channel Kondo-Heisenberg lattice away from half-filling. These models flow to an intermediate fixed point which belongs to the universality class of chirally stabilized liquids. Using a Toulouse point approach,

A. Lavagno, P. Narayana Swamy

We formulate a convenient generalization of the q-expectation value, based on the analogy of the symmetric quantum groups and q-calculus, and show that the q->q^{-1} symmetric nonextensive entropy preserves all of the mathematical structure of thermodynamics just as in the case of non-symmetric Tsallis statistics. Basic properties and analogies with quantum

Anirban Chakraborti, Bikas K. Chakrabarti

If one places N cities on a continuum in an unit area, extensive numerical results and their analysis (scaling, etc.) suggest that the best normalized optimal travel distance becomes 0.72 for the Euclidean metric and 0.92 for the Manhattan metric. The analytic bounds, we discuss here, give 0.5 and 0.92 as the lower and upper bounds for the Euclidean metric,

Lee Hartmann

The Taurus molecular cloud complex is the paradigm for quiescent, low-density, isolated star formation. Yet the age distribution of its stellar population indicates that star formation is a rapid and dynamic process, inconsistent with the old picture of magnetically-controlled protostellar cloud collapse. Instead, Taurus seems to have formed stars in a manne

John S. Arabadjis, Joel N. Bregman

A study of the cores of galaxy clusters with the Einstein SSS indicated the presence of absorbing material corresponding to 1E+12 Msun of cold cluster gas, possibly resulting from cooling flows. Since this amount of cold gas is not confirmed by observations at other wavelengths, we examined whether this excess absorption is present in the ROSAT PSPC observat

David R. Madore, Gina Hamilton

We demonstrate that gamma (from the Lorentz transformation of the Special Theory of Relativity) acts as an impediment to velocity changes only when it occurs inside motion energy transfer relationships. We also examine whether or not gamma unimpeded velocity changes violate either the constancy of light or elementary causality. We find that no violations occ

Maarten Schmidt

We have searched for gamma-ray bursts (GRBs) in the BATSE DISCLA data over a time period of 5.9 years. We employ a trigger requiring an excess of at least 5 sigma over background for at least two modules in the 50-300 keV range. After excluding certain geographic locations of the satellite, we are left with 4485 triggers. Based on sky positions, we exclude t

Maarten Schmidt

We use the BD2 sample of gamma-ray bursts (GRBs) based on 5.9 years of BATSE DISCLA data with a variety of models of the luminosity function to derive characteristic GRB luminosities, space densities and redshift distributions. Previously published results for an open universe and modest density evolution of the GRBs showed characteristic peak luminosities a

Uros Seljak, Juan Burwell, Ue-Li Pen

We use moving mesh hydrodynamical simulations to make maps of Sunyaev-Zeldovich effect. We present these maps for several cosmological models and explore their lowest moments. We find that the first moment, the mean Compton $y$ parameter, is typically between $1-2\times 10^{-6}$ for cluster abundance normalized models, the lower value corresponding to the hi

P. Rosati, S. Borgani, R. Della Ceca, S. A. Stanford

We briefly review our current knowledge of the space density of distant X-ray clusters as measured by several ROSAT serendipitous surveys. We compare old and new determinations of the cluster X-ray Luminosity Function (XLF) at increasing redshifts, addressing the controversial issue of the evolution of its high end. We use complete subsamples, drawn from the

Andrew Taylor, Peter Watts

We present a new calculation for the evolution of the 1-point Probability Distribution Function (PDF) of the cosmological density field based on an exact statistical treatment. Using the Chapman-Kolmogorov equation and second-order Eulerian perturbation theory we propagate the initial density distribution into the nonlinear regime. Our calculations yield the

R. J. R. Williams, J. E. Dyson, T. W. Hartquist

We present the jump conditions for ionization fronts with oblique magnetic fields. The standard nomenclature of R- and D-type fronts can still be applied, but in the case of oblique magnetization there are fronts of each type about each of the fast- and slow-mode speeds. As an ionization front slows, it will drive first a fast- and then a slow-mode shock int

M. Bobrowsky, B. W. Greeley, T. Ueta, M. M. Meixner

I-band images of the OH maser source OH44.8-2.3 are presented. Having a well-determined distance, this object is shown to be very young and physically small, with an asymmetric compact bipolar nebula already present. In the morphological terminology of Meixner et al. (2000) and Ueta et al. (2000), this object would be classified as a DUPLEX nebula because of

R. Turolla, C. P. Dullemond

In this Letter we investigate the properties of advection-dominated accretion flows (ADAFs) fed by the evaporation of a Shakura-Sunyaev accretion disk (SSD). In our picture the ADAF fills the central cavity evacuated by the SSD and extends beyond the transition radius into a coronal region. We find that, because of global angular momentum conservation, a sig

E. J. Totten, M. J. Irwin, P. A. Whitelock

We present proper motion measurements for carbon stars found during the APM Survey for Cool Carbon Stars in the Galactic Halo (Totten & Irwin, 1998). Measurements are obtained using a combination of POSSI, POSSII and UKST survey plates supplemented where necessary by CCD frames taken at the Isaac Newton Telescope. We find no significant proper motion for any

P. A. Caraveo

Although less than 1% of all radio pulsars are detected at optical wavelengths, their optical emission can yield a wealth of information that is either very difficult or plainly impossible to obtain at other wavelengths.

The Milagro Collaboration, R. Atkins, W. Benbow, D. Berley

Milagrito, a detector sensitive to very high energy gamma rays, monitored the northern sky from February 1997 through May 1998. With a large field of view and a high duty cycle, this instrument was well suited to perform a search for TeV gamma-ray bursts (GRBs). We report on a search made for TeV counterparts to GRBs observed by BATSE. BATSE detected 54 GRBs

J. J. M. in 't Zand, E. Kuulkers, A. Bazzano, R. Cornelisse

SAX J1819.3-2525 is a nearby X-ray transient which exhibited a fast and large X-ray outburst on Sep. 15, 1999 (Smith et al. 1999). The Wide Field Cameras and the Narrow Field Instruments (NFI) on board BeppoSAX observed SAX J1819.3-2525 at various stages of its activity before that, in the spring and fall of 1999. The fluxes range between 0.012 and 0.3 Crab

Miriam Centurion, Piercarlo Bonifacio, Paolo Molaro, Giovanni Vladilo

Relative elemental abundances, and in particular the alpha/Fe ratio, are an important diagnostic tool of the chemical evolution of damped Ly alpha systems (DLAs). The S/Zn ratio is not affected by differential dust depletion and is an excellent estimator of the alpha/Fe ratio. We report 6 new determinations of sulphur abundance in DLAs at zabs greater than o

L. V. E. Koopmans, A. G. de Bruyn

We present the results from recent VLA 8.5-GHz and WSRT 1.4 and 4.9-GHz monitoring campaigns of the CLASS gravitational lens B1600+434 and show how the observed variations argue strongly in favor of microlensing by MACHOs in the halo of a dark-matter dominated edge-on disk galaxy at z=0.4. The population of flat-spectrum radio sources with micro-Jy flux-dens

R. Gilli, R. Maiolino, A. Marconi, G. Risaliti

We report the transition to an active state of the nucleus in the Seyfert 1.9 galaxy NGC 2992, discovered by means of new hard X-ray data. While the 2-10 keV flux declined by a factor of ~ 20 from 1978 to 1994, two recent BeppoSAX observations in 1997 and in 1998 caught the nuclear emission raising back to the same level of activity observed in 1978. In both

Ruediger Kneissl

Hydrodynamical simulations are used in combination with the Press-Schechter expression to simulate Sunyaev-Zel'dovich (SZ) galaxy cluster sky maps. These are used to gauge the ability of future SZ observations to provide information about the cosmological parameters H_0, Omega_M, and the gas fraction f_g in clusters. This work concentrates on prospects f

J. U. Fynbo, W. Freudling, P. Moller

Significant uncertainties exist in the measured amplitude of the angular two-point correlation function of galaxies at magnitudes $I\approx26$ and fainter. Published results from HST and ground-based galaxy catalogs seem to differ by as much as a factor of 3, and it is not clear whether the correlation amplitude as a function of magnitude increases or decrea

Rosa M. Gonzalez Delgado, Timothy Heckman, Claus Leitherer

We present and discuss near-ultraviolet and optical ground-based spectra of the 20 brightest Seyfert 2 nuclei, and HST ultraviolet images and ultraviolet spectroscopy for a few of them. The goal is to study the starburst-AGN connection and the origin of the featureless continuum. The results indicate that half of the nuclei in the sample harbor a young and/o

T. Belloni, M. Klein-Wolt, M. Mendez, M. van der Klis

We analyzed 163 observations of the microquasar GRS 1915+105 made with the Rossi X-ray Timing Explorer (RXTE) in the period 1996-1997. For each observation, we produced light curves and color-color diagrams. We classified the observations in 12 separate classes, based on their count rate and color characteristics. From the analysis of these classes, we reduc

J. Kaluzny, A. Olech, I. Thompson, W. Pych

We present V-band CCD photometry of 65 RR Lyr variables from the globular cluster M5. We have estimated the basic physical parameters for 16 RRc stars and 26 RRab stars using a Fourier decomposition of the light curves of the variables. The mean values of mass, luminosity, effective temperature and relative helium abundance for the RRc stars are measured to

Soo-Chang Rey, Young-Wook Lee, Jong-Myung Joo, Alistair Walker

We present new measurements of the metallicity of 131 RR Lyrae stars in the globular cluster Omega Centauri, using the hk index of the Caby photometric system. The hk method has distinct advantages over Delta-S and other techniques in determining the metallicity of RR Lyrae stars, and has allowed us to obtain the most complete and homogeneous metallicity dat

S. K. Leggett, F. Allard, Conard Dahn, P. H. Hauschildt

We have obtained infrared (1 to 2.5 micron) spectroscopy for 42 halo and disk dwarfs with spectral type M1 to M6.5. These data are compared to synthetic spectra generated by the latest model atmospheres of Allard & Hauschildt. Photospheric parameters metallicity, effective temperature and radius are determined for the sample. We find good agreement between o

Andreas A. Berlind, Vijay K. Narayanan, David H. Weinberg, .

We show that a regression of unsmoothed peculiar velocity measurements against peculiar velocities predicted from a smoothed galaxy density field leads to a biased estimate of the cosmological density parameter Omega, even when galaxies trace the underlying mass distribution and galaxy positions and velocities are known perfectly. The bias arises because the

O. Almaini

It is widely believed that most of the cosmic X-ray background (XRB) is produced by a vast, hitherto undetected population of obscured AGN. Deep X-ray surveys with Chandra and XMM will soon test this hypothesis. Similarly, recent sub-mm surveys with SCUBA have revealed an analogous population of exceptionally luminous, dust-enshrouded {\em star-forming} gala

Brian R. Greene, C. I. Lazaroiu

We study the quantum volume of D-branes wrapped around various cycles in Calabi-Yau manifolds, as the manifold's moduli are varied. In particular, we focus on the behaviour of these D-branes near phase transitions between distinct low energy physical descriptions of the resulting string theory. Whereas previous studies have solely considered quantum volu

M. Roy, J. F. Mitchell, A. P. Ramirez, P. Schiffer

We present a detailed magnetothermal study of Pr(0.7)Ca(0.3)MnO(3), a perovskite manganite in which an insulator-metal transition can be driven by magnetic field, but also by pressure, visible light, x-rays, or high currents. We find that the field-induced transition is associated with an enormous release of energy which accounts for its strong irreversibili

John Phillips, David H. Weinberg, Rupert A. C. Croft, Lars Hernquist

We combine COBE-DMR measurements of cosmic microwave background anisotropy with a recent measurement of the mass power spectrum at redshift z=2.5 from Lya forest data to derive constraints on cosmological parameters and test the inflation+CDM scenario of structure formation. By treating the inflationary spectral index n as a free parameter, we can find succe

Takashi Okamoto, Asao Habe

Using cosmological N-body simulations of critical (SCDM) and open ($Ω= 0.3$, OCDM) cold dark matter models, we investigate evolution of cluster galaxies. From our numerical simulation, we construct merging history trees of the galaxies. By following their merging history, we show major merger fractions of the galaxies in cluster forming regions is roughly pr

Jerome P. Gauntlett, Gary W. Gibbons, Christopher M. Hull, Paul K. Townsend

We find the combinations of momentum and domain-wall charges corresponding to BPS states preserving 1/4, 1/2 or 3/4 of D=4 N=1 supersymmetry, and we show how the supersymmetry algebra implies their stability. These states form the boundary of the convex cone associated with the Jordan algebra of $4\times 4$ real symmetric matrices, and we explore some implic

Carlos Castro

The String Uncertainty Relations have been known for some time as the stringy corrections to the original Heisenberg's Uncertainty principle. In this letter the Stringy Uncertainty relations, and corrections thereof, are explicitly derived from the New Relativity Principle that treats all dimensions and signatures on the same footing and which is based o

A. Borriello, P. Salucci

We use high-quality optical rotation curves of 9 low-luminosity disk galaxies to obtain the velocity profile of the surrounding dark matter halos. We find that they increase linearly with radius at least out to the stellar disk edge, implying that, over the entire region where the stars reside, the density of the dark halo is constant. The properties of the

E. Boos, M. Dubinin, M. Sachwitz, H. J. Schreiber

The Wtb vertex can be probed on future colliders in the processes of single top production (LHC, pp mode, NLC, $γe$ mode) and of top pair production (NLC, e^+ e^- mode). We analyse observables sensitive to anomalous Wtb couplings in the top pair production process of e^+ e^- collisions. In particular, forward-backward and spin-spin asymmetries of the top dec

Friedrich W. Hehl, Yuri N. Obukhov

The coupling of the electromagnetic field to gravity is an age-old problem. Presently, there is a resurgence of interest in it, mainly for two reasons: (i) Experimental investigations are under way with ever increasing precision, be it in the laboratory or by observing outer space. (ii) One desires to test out alternatives to Einstein's gravitational the

Andrei Rybin, Gennadii Varzugin, Markus Lindberg, Jussi Timonen

We analyse a generalised Gross-Pitaevskii equation involving a paraboloidal trap potential in $D$ space dimensions and generalised to a nonlinearity of order $2n+1$. For {\em attractive} coupling constants collapse of the particle density occurs for $Dn\ge 2$ and typically to a $δ$-function centered at the origin of the trap. By introducing a new dynamical v

Gao Shan

We show that the natural motion of particles in continuous space-time (CSTM) is not classical continuous motion (CCM), but one kind of essentially discontinuous motion, the wave function in quantum mechanics is the very mathematical complex describing this kind of motion, and Schrodinger equation is just its simplest nonrelativistic motion equation, we call

Alejandro Ayala, Sarira Sahu, Mauro Napsuciale

We develop one-loop effective vertices and propagators in the linear sigma model at finite temperature satisfying the chiral Ward identities. We use these in turn to compute the pion dispersion relation in a pion medium for small momentum and temperatures on the order of the pion mass at next to leading order in the parameter m_pi^2/4pi^2f_pi^2 and to zeroth

E. W. Carlson, D. Orgad, S. A. Kivelson, V. J. Emery

The one-dimensional electron gas exhibits spin-charge separation and power-law spectral responses to many experimentally relevant probes. Ordering in a quasi one-dimensional system is necessarily associated with a dimensional crossover, at which sharp quasiparticle peaks, with small spectral weight, emerge from the incoherent background. Using methods of Abe

V. B. Svetovoy, M. V. Lokhanin

An upper limit on the Casimir force is found using the dielectric functions of perfect crystalline materials which depend only on well defined material constants. The force measured with the atomic force microscope is larger than this limit at small separations between bodies and the discrepancy is significant. The simplest modification of the experiment is

Miroljub Dugić

Controlable strong interaction of the qubit's bath with an external system (i.e. with the bath's environment) allows for choosing the conditions under which the decoherence of the qubit's states can be substantially decreased (in a certain limit: completely avoided). By "substantially decreased" we mean that the correlations which involve

Yong-Sheng Zhang, Chuan-Feng Li, Wan-Li Li, Yun-Feng Huang

Quantum gambling --- a secure remote two-party protocol which has no classical counterpart --- is demonstrated through optical approach. A photon is prepared by Alice in a superposition state of two potential paths. Then one path leads to Bob and is split into two parts. The security is confirmed by quantum interference between Alice's path and one part

R. Marani, L. Cognet, V. Savalli, N. Westbrook

We show that atomic interference in the reflection from two suitably polarized evanescent waves is sensitive to retardation effects in the atom-surface interaction for specific experimental parameters. We study the limit of short and long atomic de Broglie wavelength. The former case is analyzed in the semiclassical approximation (Landau-Zener model). The la

Michael Schreiber, Dmitry Kilin, Ulrich Kleinekathoefer

Optical excitation of the sequential supermolecule H_2P-ZnP-Q induces an electron transfer from the free-base porphyrin (H_2P) to the quinone (Q) via the zinc porphyrin (ZnP). This process is modeled by equations of motion for the reduced density matrix which are solved numerically and approximately analytically. These two solutions agree very well in a grea