April 1999 arXiv papers — page 6

Andrzej M. Oles, Louis Felix Feiner, Jan Zaanen

We study the effective spin-orbital model derived for the d9 ions in a three-dimensional perovskite lattice, as in KCuF_3, where at each site the doubly degenerate eg orbitals contain a single hole. The model describes the superexchange interactions that depend on the pattern of orbitals occupied. We present the ground state properties of this model, dependi

B. J. Mochejska, J. Kaluzny, K. Z. Stanek, M. Krockenberger

We undertook a long term project, DIRECT, to obtain the direct distances to two important galaxies in the cosmological distance ladder -- M31 and M33 -- using detached eclipsing binaries (DEBs) and Cepheids. While rare and difficult to detect, DEBs provide us with the potential to determine these distances with an accuracy better than 5%. The extensive photo

Sandip K. Chakrabarti, Banibrata Mukhopadhyay

We study nucleosynthesis in low accretion rate hot advective flows around black holes. We find that matter is generally photo-dissociated into protons and neutrons inside the disk. These neutrons stay around black holes for longer time because they are not coupled to magnetic fields while the protons accrete into the hole. We find the nature of the resulting

Giorgio Matt, Fulvio Pompilio, Fabio La Franca

X-ray spectra transmitted through matter which is optically thick to Compton scattering are computed by means of Monte Carlo simulations. Applications to the BeppoSAX data of the Seyfert 2 galaxy in Circinus, and to the spectral modeling of the Cosmic X-ray Background, are discussed.

Geza Gyuk, Arlin Crotts

We provide a set of microlensing optical depth maps for M31. Optical depths towards Andromeda were calculated on the basis of a four component model of the lens and source populations: disk and bulge sources lensed by bulge, M31 halo and Galactic halo lenses. We confirm the high optical depth and the strong optical depth gradient along the M31 minor axis due

Xinwei Kong, Finn Ravndal

Proton-proton fusion is considered in the effective field theory of Kaplan, Savage and Wise. Coulomb effects are included systematically in a non-perturbative way. Including the dimension-eight derivative coupling which determines the effective ranges of the scattering amplitudes, next-to-leading order corrections to the fusion rate are calculated. When the

David H. Evans, Benjamin Grinstein, Detlef R. Nolte

The decays $B^+\to D_{s,d}^+e^+e^-$ and $B^+\to D_{s,d}^{*+}e^+e^-$ proceed through a weak and an electromagnetic interaction. This is a typical ``long distance'' process, usually difficult to compute systematically. We propose that over a large fraction of phase space a combination of an operator product and heavy quark expansions effectively turns

Alice Sinatra, Yvan Castin

We investigate the relative phase coherence properties and the occurrence of demixing instabilities for two mutually interacting and time evolving Bose-Einstein condensates in traps. Our treatment naturally includes the additional decoherence effect due to fluctuations in the total number of particles. Analytical results are presented for the breathe-togethe

Tomas S. Grigera, N. E. Israeloff

The fluctuation-dissipation theorem (FDT), connecting dielectric susceptibility and polarization noise was studied in glycerol below its glass transition temperature Tg. Weak FDT violations were observed after a quench from just above to just below Tg, for frequencies above the alpha peak. Violations persisted up to 10^5 times the thermal equilibration time

P. R. Wozniak, C. Alard, A. Udalski, M. Szymanski

We present results from 2 years of monitoring of Huchra's lens (QSO 2237+0305) with the 1.3 m Warsaw telescope on Las Campanas, Chile. Photometry in the V band was done using a newly developed method for image subtraction. Reliable subtraction without Fourier division removes all complexities associated with the presence of a bright lensing galaxy. With

R. J. Keizer, A. de Visser, A. A. Menovsky, J. J. M. Franse

We report mSR experiments carried out on a series of heavy-electron pseudobinary compounds U(Pt1-xPdx)3 (x<=0.05). For x<=0.005 the zero-field muon depolarisation is described by the Kubo-Toyabe function. However the temperature variation of the Kubo-Toyabe relaxation rate does not show any sign of the small-moment antiferromagnetic phase with TN~6 K (signal

Bihn Zhou, Chuan-Jie Zhu

In this letter we present the complete explicit brane solution in D-dimensional coupled gravity system.

F. Bernd Mueller-Allinger, Ana Celia Mota

We discuss the magnetic response of clean Ag coated Nb proximity cylinders in the temperature range 150 μK < T < 9 K. In the mesoscopic temperature regime, the normal metal-superconductor system shows the yet unexplained paramagnetic reentrant effect, discovered some years ago [P. Visani, A. C. Mota, and A. Pollini, Phys. Rev. Lett. 65, 1514 (1990)], superim

Renato Vicente, David Saad, Yoshiyuki Kabashima

We investigate the performance of parity check codes using the mapping onto Ising spin systems proposed by Sourlas. We study codes where each parity check comprises products of K bits selected from the original digital message with exactly C checks per message bit. We show, using the replica method, that these codes saturate Shannon&#39;s coding bound for $K

Andris Ambainis, Ronald de Wolf

We compare classical and quantum query complexities of total Boolean functions. It is known that for worst-case complexity, the gap between quantum and classical can be at most polynomial. We show that for average-case complexity under the uniform distribution, quantum algorithms can be exponentially faster than classical algorithms. Under non-uniform distri

Silvia Vernetto

Ground based extensive air showers arrays can observe GRBs in the 1-1000 GeV energy range using the &#34;single particle&#34; techique. The sensitivity to detect a GRB as a function of the burst parameters and the detector characteristics are discussed. The rate of possible observations is evaluated, making reasonable assumptions on the high energy emission,

Stefan Dittmaier

Soft or collinear photon emission potentially poses numerical problems in the phase-space integration of radiative processes. In this paper, a general subtraction formalism is presented that removes such singularities from the integrand of the numerical integration and adds back the analytically integrated contributions that have been subtracted. The method

Vidar Frette, Ilan Tsafrir, Marie-Alice Guedeau-Boudeville, Ludovic Jullien

We study experimentally a coiling instability of cylindrical multilamellar stacks of phospholipid membranes, induced by polymers with hydrophobic anchors grafted along their hydrophilic backbone. We interpret our experimental results in terms of a model, in which local membrane curvature and polymer concentration are coupled. The model predicts the occurence

Kazuo Fujikawa

The relation $Tr γ_{5}= 0$ implies the contribution to the trace from unphysical (would-be) species doublers in lattice gauge theory. This statement is also true for the Pauli-Villars regularization in continuum theory. If one insists on $Tr γ_{5}= 0$, one thus inevitably includes unphysical states in the Hilbert space. If one truncates the trace to the cont

T. Asaka, M. Kawasaki, T. Yanagida

The thermal inflation is the most plausible mechanism that solves the cosmological moduli problem naturally. We discuss relic abundance of superheavy particle $X$ in the presence of the thermal inflation assuming that its lifetime is longer than the age of the universe, and show that the long-lived particle $X$ of mass $10^{12}$--$10^{14}$ GeV may form a par

Bishwajyoti Dey, Avinash Khare

We consider fifth-order nonlinear dispersive $K(m,n,p)$ type equations to study the effect of nonlinear dispersion. Using simple scaling arguments we show, how, instead of the conventional solitary waves like solitons, the interaction of the nonlinear dispersion with nonlinear convection generates compactons - the compact solitary waves free of exponential t

Mitsuko Abe, Masamichi Sato

We discuss the possibility of the extension of the duality between the webs of heterotic string and the type IIA string to Calabi-Yau 3-folds with another K3 fiber by comparing the dual polyhedron of Calabi-Yau 3-folds given by Candelas, Perevalov and Rajesh.

David E. Rosenberg

Eliptical and bulge galaxies share a tight correlation of velocity distribution to both luminosity and black hole mass. There are similar orbital speeds for all galaxies of a given luminosity including dark matter (DM) at large radii. The halo surface density of DM is constant for almost all types of galaxies and ranges 14 mag. down to dwarf spherical galaxi

C. Nagaraja Kumar, Prasanta K. Panigrahi

We present compacton-like solution of the modified KdV equation and compare its properties with those of the compactons and solitons. We further show that, the nonlinear Schr{ö}dinger equation with a source term and other higher order KdV-like equations also possess compact solutions of the similar form.

Piotr Garbaczewski

The third Newton law for mean velocity fields is utilised to generate anomalous (enhanced) or non-dispersive diffusion-type processes which, in particular, can be interpreted as a probabilistic counterpart of the Schrödinger picture quantum dynamics.

J. F. Babb

For the interactions between two atoms or between an ion and an electron the connections between the Casimir-Polder-type potentials and the relativistic potentials arising from the Breit-Pauli Hamiltonian are surveyed.

B. G. Sidharth

It is pointed out, that in the light of recent results on the semionic or anomalous behaviour of electrons below the Fermi temperature, the solid core of the earth which has been ignored so far, would contribute significantly to Geomagnetism and help explain the puzzling magnetic reversals.

Petr Vogel

Study of the neutrinoless $ββ$ decay allows us to put a stringent limit on the effective neutrino Majorana mass, a quantity of fundamental importance. To test our ability to evaluate the nuclear matrix elements that govern the decay rate, it is desirable to be able to describe the allowed two-neutrino decay. It is argued that only low-lying virtual intermedi

B. Q. Chen, Z. Y. Ma, F. Gruemmer, S. Krewald

Density dependent relativistic Hartree-Fock theory has been extended to describe properties of exotic nuclei. The effects of Fock exchange terms and of pi - and rho - meson contributions are discussed. These effects are found to be more important for neutron rich nuclei than for nuclei near the valley of stability.

D. V. Anchishkin, W. A. Zajc, G. M. Zinovjev

The corrections for two-pion correlations due to electromagnetic final-state interactions at high secondary multiplicities are investigated. The analysis is performed by solving the Schrödinger equation with a potential which is dictated by the multi-particle environment. Two different post-freeze-out scenarios are examined. First, for a uniformly spread env

Divakar Viswanath

For the ordinary differential equation (ODE) $\dot{x}(t) = f(t,x)$, $x(0) = x_0$, $t\geq 0$, $x\in R^d$, assume $f$ to be at least continuous in $t$ and locally Lipshitz in $x$, and if necessary, several times continuously differentiable in $t$ and $x$. We associate a conditioning function $E(t)$ with each solution $x(t)$ which captures the accumulation of g

P. Collet

For non uniformly hyperbolic maps of the interval with exponential decay of correlations we prove that the law of closest return to a given point when suitably normalized is almost surely asymptotically exponential. A similar result holds when the reference point is the initial point of the trajectory. We use the framework for non uniformly hyperbolic dynami

Boris Tsygan

We state the analogs of Kontsevich&#39;s formality conjecture for Hochschild and cyclic chains, as well as their

Viktor L. Ginzburg, Victor Guillemin, Yael Karshon

moment maps arise as a generalization of genuine moment maps on symplectic manifolds when the symplectic structure is discarded, but the relation between the mapping and the action is kept. Particular examples of abstract moment maps had been used in Hamiltonian mechanics for some time, but the abstract notion originated in the study of cobordisms of Hamilto

T. Ioannidou, B. Piette, W. J. Zakrzewski

Recently we have presented in hep-th/9811071 an ansatz which allows us to construct skyrmion fields from the harmonic maps of $S\sp2$ to $CP\sp{N-1}$. In this paper we examine this construction in detail and use it to construct, in an explicit form, new static spherically symmetric solutions of the SU(N) Skyrme models. We also discuss some properties of thes

F. A. S. Nobre, C. A. S. Almeida

In this work we consider an Abelian Chern-Simons-Higgs model coupled non-minimally to matter fields. This coupling is implemented by means of a Pauli-type coupling. We show that the Pauli term is sufficient to gives rise to fractional spin.

Antonio F. Ranada

A recently proposed topological mechanism for the quantization of the charge gives the value e_0=\sqrt{\hbar c} for both the fundamental electric and magnetic charges. It is argued that the corresponding fine structure constant α_0=1/4pi could be interpreted as its value at the unification scale.

B. Chakraborty, A. S. Majumdar

We study the gauged Landau-Lifshitz model in which a suitably chosen triplet of background scalar fields is included. It is shown that the model admits solitonic configurations.

K. Bresser, G. Pinter, D. Prange

In the framework of causal perturbation theory renormalization consists of the extension of distributions. We give the explicit form of a Lorentz invariant extension of a scalar distribution, depending on one difference of space time coordinates.

Paolo Lipari

The predictions of the atmospheric nu event rates are affected by significant uncertainties, however the evidence for the `disappearance&#39; of nu_mu&#39;s and nubar_mu&#39;s obtained by SK (and other underground detectors) is robust and cannot be accounted in the framework of the minimum standard model without assuming very large ad hoc experimental system

C. Unkmeir, S. Scherer, A. I. L&#39;vov, D. Drechsel

We present a calculation of the virtual Compton scattering amplitude for $γ^\ast+π\to γ+π$ in the framework of chiral perturbation theory at ${\cal O}(p^4)$. We explicitly derive expressions for generalized electromagnetic polarizabilities and discuss alternative definitions of these quantities.

N. N. Achasov, V. V. Gubin

The potentialities of the production of the $a_0(980)$ and $f_0(980)$ mesons in the $ϕ$ radiative decays are considered.

R. R. Volkas

Improper Lorentz Transformations can be retained as exact symmetries of Nature if the particle content and gauge group of the Standard Model are doubled. The resulting ``Exact Parity Model (EPM)&#39;&#39; sees each ordinary particle paired with a mirror analogue. If neutrinos have mass and if they mix, then the EPM predicts that each ordinary neutrino will b

Sa Ben-Hao, Wang Xiao-Rong, Tai An, Zhou Dai-Cui

The idea that the reduction of the strange quark suppression in string fragmentation leads to the enhancement of strange particle yield in nucleus-nucleus collisions is applied to study the singly and multiply strange particle production in p-Pb and Pb-Pb collisions at 158A GeV/c. In this mechanism the strange quark suppression factor is related to the effec

Kang Young Lee

Motivated by $-2 σ$ deviation from the Standard Model prediction for the forward--backward asymmetry of $Z \to b \bar{b}$ decay in the LEP data, we explore the anomalous couplings of $Z b \bar{b}$ vertex through the electroweak precision test extended by including $A_{FB}^b$. We introduce a new variable $ε&#39;_b$ to measure the anomalous right-handed coupli

G. Lazarides

A supersymmetric model based on a left-right symmetric gauge group, which `naturally&#39; leads to hybrid inflation, is studied. It is shown that the mu problem can be easily solved in this model. The observed baryon asymmetry of the universe is produced via a primordial leptogenesis. For masses of nu_mu, nu_tau from the small angle MSW resolution of the sol

Ilya Narsky

Bayesian, classical, and extended maximum likelihood approaches to estimation of upper limits in experiments with small numbers of signal events are surveyed. The discussion covers only experiments whose outcomes are well described by a Poisson statistic. A new approach, based on the statistical significance of a signal rather than on the number of events in

Richard J. Tesarek

In the past few years charged kaon experiments have indicated possible scalar and tensor couplings in semileptonic kaon decays(K --> pi e nu). These couplings, if correct, are not predicted by the Standard Model and may indicate the onset of new physics. We present a summary of the existing data and a new, precision measurement of these couplings in the neut

Nils Andersson, Kostas D. Kokkotas, Pablo Laguna, Philippos Papadopoulos

We develop a framework for constructing initial data sets for perturbations about spherically symmetric matter distributions. This framework facilitates setting initial data representing astrophysical sources of gravitational radiation involving relativistic stars. The procedure is based on Lichnerowicz-York&#39;s conformal approach to solve the constraints

David R. Hanson

Most debuggers are notoriously machine-dependent, but some recent research prototypes achieve varying degrees of machine-independence with novel designs. Cdb, a simple source-level debugger for C, is completely independent of its target architecture. This independence is achieved by embedding symbol tables and debugging code in the target program, which cost

George Stan, Silvina M. Gatica, Massimo Boninsegni, Stefano Curtarolo

Newly discovered carbon nanotubes provide an environment in which small atoms move relatively freely. An assembly of such atoms provides a realization of a quasi-one dimensional system which is an ideal testing ground for concepts and mathematics of statistical physics.

M. Trzeciecki, A. Daehn, W. Huebner

Using group theory we classify the nonlinear magneto-optical response at low-index surfaces of fcc antiferromagnets, such as NiO. Structures consisting of one atomic layer are discussed in detail. We find that optical second harmonic generation is sensitive to surface antiferromagnetism in many cases. We discuss the influence of a second type of magnetic ato

Y. Sidis, M. Braden, P. Bourges, B. Hennion. S. Nishizaki

We report first inelastic neutron scattering measurements in the normal state of Sr_2RuO_4 that reveal the existence of incommensurate magnetic spin fluctuations located at ${\bf q}_0=(\pm 0.6π/a, \pm 0.6π/a, 0)$. This finding confirms recent band structure calculations that have predicted incommensurate magnetic responses related to dynamical nesting proper

J. A. Sanchez-Gil, A. A. Maradudin

A rigorous formulation for the scattering of surface plasmon polaritons (SPP) from a one-dimensional surface defect of any shape that yields the electromagnetic field in the vacuum half-space above the vacuum-metal interface is developed by the use of an impedance boundary condition. The electric and magnetic near fields, the angular distribution of the far-

H. Schwenk, S. Zherlitsyn, B. Luethi, E. Morre

We present the temperature dependence of shear and longitudinal elastic constants in a&#39;-NaV2O5. For the longitudinal c22 and c33 modes we find anomalies at Tc in contrast to the Spin Peierls substance CuGeO3 where only the longitudinal mode along the chain shows a pronounced effect at TSP. The c66 shear mode (propagation along the chain in b-direction po

A. De Nardis, V. Pellegrini, R. Colombelli, F. Beltram

We present a detailed investigation of excitonic absorption in $Zn_{0.69}Cd_{0.31}Se/ZnSe$ quantum wells under the application of a perpendicular magnetic field. The large energy separation between heavy- and light-hole excitons allows us to clearly resolve and identify magneto-excitonic absorption resonant with the continuum edge of the 1S heavy-hole excito

Alain Verberkmoes, Bernard Nienhuis

A model is presented consisting of triangular trimers on the triangular lattice. In analogy to the dimer problem, these particles cover the lattice completely without overlap. The model has a honeycomb structure of hexagonal cells separated by rigid domain walls. The transfer matrix can be diagonalised by a Bethe Ansatz with two types of particles. This lead

B. R. Bulka, J. Martinek, G. Michalek, J. Barnas

Frequency dependent current noise in ferromagnetic double junctions with Coulomb blockade is studied theoretically in the limit of sequential tunneling. Two different relaxation processes are found in the correlations between spin polarized tunneling currents; low frequency spin fluctuations and high frequency charge fluctuations. Spin accumulation in strong

T. Plackowski, M. Matusiak

A method for measurements of small (metallic) Ettingshausen coefficient (P) was developed. The influence of the dominating thermal effects, the Joule and Thomson heats, was eliminated making use of the odd symmetry of the Ettingshausen temperature gradient in respect with reversing of the direction of the magnetic field and electrical current. The method was

J. D. Lee, O. Gunnarsson, L. Hedin

We consider core electron photoemission in a localized system, where there is a charge transfer excitation. The system is modelled by three electron levels, one core level and two outer levels. The model has a Coulomb interaction between these levels and the continuum states into which the core electron is emitted. The model is simple enough to allow an exac

U. Schneider, P. Lunkenheimer, R. Brand, A. Loidl

We have performed dielectric spectroscopy on the molecular glass-formers glycerol, propylene carbonate (PC) and the ionic melts CKN and CRN. The frequency range covers almost 20 decades from some micro-Hz to some THz. The meausrement results are compared to neutron and light scattering data and analysed with mode coupling theory.

M. W. Lee, D. Sornette, L. Knopoff

We study the statistics of simulated earthquakes in a quasistatic model of two parallel heterogeneous faults within a slowly driven elastic tectonic plate. The probability that one fault remains dormant while the other is active for a time Dt following the previous activity shift is proportional to the inverse of Dt to the power 1+x, a result that is robust

M. Abolfath, H. Hamidian, A. Langari

We study quantum ferrimagnets in one, two, and three dimensions by using a variety of methods and approximations. These include: (i) a treatment based on the spin coherent state path-integral formulation of quantum ferrimagnets by taking into account the leading order quantum and thermal fluctuations (ii) a field-theoretical (non-linear $σ$-model type) formu

Guido Boffetta, Vincenzo Carbone, Paolo Giuliani, Pierluigi Veltri

We study the time evolution of Solar Flares activity by looking at the statistics of quiescent times $τ_{L}$ between successive bursts. The analysis of 20 years of data reveals a power law distribution with exponent $α\simeq 2.4$ which is an indication of complex dynamics with long correlation times. The observed scaling behavior is in contradiction with the

Zoltan Haiman, Abraham Loeb

It is currently unknown whether the Universe was reionized by quasars or stars at z>5. We point out that quasars can be best distinguished from stellar systems by their X-ray emission. Based on a simple hierarchical CDM model, we predict the number counts and X-ray fluxes of quasars at high redshifts. The model is consistent with available data on the lumino

B. Scott Gaudi, Penny D. Sackett

Microlensing light curves are now being monitored with the precision required to detect small perturbations due to planetary companions of the primary lens. Microlensing is complementary to other planetary search techniques in its potential for measuring the statistical frequency of planets beyond the solar neighborhood. We present an algorithm to analyze th

Petr Vogel

Neutrinos from a future Galactic supernova will be detected by several large underground detectors, in particular by SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO). If, as expected, the $ν_μ$ and $ν_τ$ neutrinos have somewhat higher energy on average that the electron neutrinos, they will dominate the neutral current response. The ways to se

D. J. Macomb, M. H. Finger, B. A. Harmon, R. C. Lamb

We report on the detection of pulsed, broad-band, X-ray emission from the transient source RX J0117.6-7330. The pulse period of 22 seconds is detected by the ROSAT/PSPC instrument in a 1992 Sep 30 - Oct 2 observation and by the CGRO/BATSE instrument during the same epoch. Hard X-ray pulsations are detectable by BATSE for approximately 100 days surrounding th

D. Mitra, A. A. Deshpande

Characterizing the shape and evolution of pulsar radio emission beams is important for understanding the observed emission. The various attempts by earlier workers investigating beam shapes have resulted in widely different conclusions. Using a carefully selected subset of the recently published multifrequency polarimetry observations of 300 radio pulsars (G

G. Zamorani, M. Mignoli, G. Hasinger, R. Burg

We present the X-ray data and the optical identifications for a deep ROSAT PSPC observation in the &#34;Marano field&#34;. In the inner region of the ROSAT field (15&#39; radius) we detected 50 X-ray sources with Sx >= 3.7x10^(-15) erg/cm^2/s. When corrected for the different sensitivity over the field, the estimated observed surface density at Sx >= 4x10^(-

Luis Mendoza, Craig J. Hogan

A simple Java applet is presented which allows quick and easy computation and plotting of the predictions of light element abundances in SBBN, including errors in the predictions propagated from input reaction rates correlated and calibrated via Monte Carlo. The applet, which requires Java 1.1-compatible browsers, can be found at http://www.astro.washington.

Ann I. Zabludoff

We use a new fiber spectroscopic survey of 12 nearby, poor groups of galaxies to examine the dynamics and evolution of galaxies in these common, but poorly studied, environments. Some of our conclusions are: (1) The nine groups in our sample with diffuse X-ray emission are in fact bound systems with at least 20-50 group members with absolute magnitudes as fa

Luciano Burderi, Andrea Possenti, Monica Colpi, Tiziana Di Salvo

Fast spinning neutron stars, recycled in low mass binaries, may have accreted a substantial amount of mass. The available relativistic measurements of neutron star masses, all clustering around 1.4 M_sun, however refer mostly to slowly rotating neutron stars which accreted a tiny amount of mass during evolution in a massive binary system. We develop a semi-a

Carl H. Gibson

It is crucial to understand the extreme intermittency of ocean and lake turbulence and turbulent mixing in order to estimate vertical fluxes of momentum, heat and mass by Osborn-Cox flux-dissipation methods. Vast undersampling errors occur by this method when intermittency is not taken into account. Oceanic turbulence increases intermittency as the result of

William H. Lee, Wlodzimierz Kluzniak

We present a numerical study of the hydrodynamics in the final stages of inspiral of a black hole-neutron star binary, when the binary separation becomes comparable to the stellar radius. We use a Newtonian three-dimensional Smooth Particle Hydrodynamics (SPH) code, and model the neutron star with a soft (adiabatic index Gamma=5/3) polytropic equation of sta

T. Treu, M. Stiavelli, S. Casertano, P. Møller

We present measurements of the Fundamental Plane (FP) parameters (the effective radius, the mean effective surface brightness, and the central velocity dispersion) of six field elliptical galaxies at intermediate redshift. The imaging is taken from the Medium Deep Survey of the Hubble Space Telescope, while the kinematical data are obtained from long-slit sp

Olga K. Sil&#39;chenko

We present the results of the spectral investigation of the regular Sb galaxy NGC 7331 with the Multi-Pupil Field Spectrograph of the 6m telescope. The absorption-line indices H-beta, Mgb, and <Fe> are mapped to analyse the properties of the stellar populations in the circumnuclear region of the galaxy. The central part of the disk inside ~3&#34; (200 pc) --

R. I. Hynes, P. A. Charles, C. A. Haswell, J. Casares

We present time-resolved spectroscopy of the soft X-ray transient XTE J2123-058 in outburst. Spectral coverage of 3700-6700A was achieved spanning two orbits of the binary. The strongest emission lines are HeII 4686A and CIII/NIII 4640A (Bowen blend). Other weak emission lines of HeII and CIV are present and Balmer lines show a complex structure, possibly co

M. Soida, M. Urbanik, R. Beck, R. Wielebinski

We present 10.55 GHz observations of strong density-wave spiral NGC 3627. Total power and polarization maps with a resolution of 1.13&#39;, sensitive to a weak extended emmision were obtained. In the analysiz we used also available data in the CO ans H_alpha lines. We present simple modelling results showing the imprtance of large-scale dynamo-type magnetic

Xinwu Cao, D. R. Jiang

Radio emission is a good indicator of the jet power of radio-loud quasars, while the emission in broad-line can well represent the accretion disc radiation in quasars. We compile a sample of all sources of which the broad-line fluxes are available from 1 Jy, S4 and S5 radio source catalogues. A correlation between radio and broad-line emission for this sampl

J. X. Wang, Y. Y. Zhou, H. G. Xu, T. G. Wang

We present a detailed analysis on the variability of the Fe K emission line in NGC 4051 using ASCA data. Through simple Gaussian line fits, we find not only obvious Fe K line variability with no significant difference in the X-ray continuum flux between two ASCA observations which were separated by $\sim$ 440 days, but also rapid variability of Fe K line on

Frank Bertoldi, Ralf Timmermann, Dirk Rosenthal, Siegfried Drapatz

We report a detection in the interstellar medium of an infrared transition within the electronic ground state of the deuterated hydrogen molecule, HD. Through a deep integration with the Short-Wavelength-Spectrometer on ISO, the pure rotational v=0-0 R(5) line at 19.43um was detected toward the Orion (OMC-1) outflow at its brightest H_2 emission region, Peak

Yuval Yaish, Oleg Prus, Evgeny Buchstab, Shye Shapira

The &#34;metallic&#34; regime of holes in GaAs/AlGaAs heterostructures corresponds to densities where two splitted heavy hole bands exist at a zero magnetic field. Using Landau fan diagrams and weak field magnetoresistance curves we extract the carrier density in each band and the interband scattering rates. The measured inelastic rates depend Arrheniusly on

Koichi Yoshioka

Recently various phenomenological implications of the existence of extra space-time dimensions have been investigated. In this letter, we construct a model with realistic fermion mass hierarchy with (large) extra dimensions beyond the usual four dimensions. In this model, it is assumed that some matter fields live in the bulk and the others are confined on o

Anthony N. Aguirre

Estimates of the cosmic star formation rate and of cluster metallicities independently imply that at z < 0.5 the gas in the universe has substantial average metallicity: 1/10 < Z/Z_solar < 1/3 for Omega_gas = 0.05. This metal density probably cannot be contained in known solar-metallicity galaxies of density parameter Omega_star ~ 0.004, implying significant

Dominic Mayers, Louis Salvail, Yoshie Chiba-Kohno

In coin tossing two remote participants want to share a uniformly distributed random bit. At the least in the quantum version, each participant test whether or not the other has attempted to create a bias on this bit. It is requested that, for b = 0,1, the probability that Alice gets bit b and pass the test is smaller than 1/2 whatever she does, and similarl

Gregorio Malajovich

The class $\mathcal{UP}$ of `ultimate polynomial time' problems over $\mathbb C$ is introduced; it contains the class $\mathcal P$ of polynomial time problems over $\mathbb C$. The $\tau$-Conjecture for polynomials implies that $\mathcal{UP}$ does not contain the class of non-deterministic polynomial time problems definable without constants over $\mathbb C$

S. J. Pollock, M. C. Welliver

We have examined modifications to the nuclear weak charge due to small differences between the spatial distributions of neutrons and protons in the Cs nucleus. We derive approximate formulae to estimate the value and uncertainty of this modification based only on nuclear rms neutron and proton radii. Present uncertainties in neutron distributions in Cs are d

Edi Halyo

We estimate the strength and range of forces mediated by string moduli in type I string models with two (or more) large internal dimensions. We find that forces mediated by twisted moduli which live on the brane world--volume can mediate forces which are orders of magnitude stronger than gravity with a range up to a milimeter. If they exist, these forces can

Hooman Davoudiasl

Recently, it has been proposed that the fundamental scale of quantum gravity can be close to the weak scale if there are large extra dimensions. This proposal has important phenomenological implications for processes at the TeV scale. We study the process gamma gamma -> gamma gamma, assuming an ultraviolet cutoff M_S \sim 1 TeV for the effective gravity theo

E. Dekel, D. Gershoni, E. Ehrenfreund, J. M. Garcia

We applied low temperature diffraction limited confocal optical microscopy to spatially resolve, and spectroscopically study photoluminescence from single self-assembled semiconductor quantum dots. Using selective wavelength imaging we unambiguously demonstrated that a single photoexcited quantum dot emits light in a few very narrow spectral lines. The measu

Kasper Olsen, Richard J. Szabo

The various descent and duality relations among BPS and non-BPS D-branes are classified using topological K-theory. It is shown how the descent procedures for producing type-II D-branes from brane-antibrane bound states by tachyon condensation and $\klein$ projections arise as natural homomorphisms of K-groups generating the brane charges. The transformation

Gregorio Malajovich

Lower bounds for some explicit decision problems over the complex numbers are given.

Gregorio Malajovich

An apriori bound for the condition number associated to each of the following problems is given: general linear equation solving, minimum squares, non-symmetric eigenvalue problems, solving univariate polynomials, solving systems of multivariate polynomials. It is assumed that the input has integer coefficients and is not on the degenerate locus of the respe

V. Cardenas, G. Palma

In a recent paper Damour and Mukhanov describe a scenario where inflation may continue during the oscillatory phase. This effect is possible because the scalar field spends a significant fraction of each period of oscillation on the upper part of the potential. Such additional period of inflation could push perturbations after the slow roll regime to observa

Everton M. C. Abreu, Anderson Ilha, Clifford Neves, Clovis Wotzasek

The classification of the regularization ambiguity of 2D fermionic determinant in three different classes according to the number of second-class constraints, including the new faddeevian regularization, is examined and extended. We found a new and important result that the faddeevian class, with three second-class constraints, possess a free continuous one

C. P. Dettmann, E. G. D. Cohen, H. van Beijeren

A recent experiment on Brownian motion has been interpreted to exhibit direct evidence for microscopic chaos. In this note we demonstrate that virtually identical results can be obtained numerically using a manifestly microscopically nonchaotic system.

Vibhat Nair

The number of galaxies with measured redshifts > 1 is at present rapidly increasing, allowing for measurements of their correlation function. The correlations function is measured in redshift space, as a function of angular separation and velocity difference. The relation between angle and velocity difference depends on the cosmological model through the fac

Dirk Helbing, Tamas Vicsek

We present computational and analytical results indicating that systems of driven entities with repulsive interactions tend to reach an optimal state associated with minimal interaction and minimal dissipation. Using concepts from non-equilibrium thermodynamics and game theoretical ideas, we generalize this finding to an even wider class of self-organizing s

Ernest Ma

If a global continuous symmetry of a supersymmetric field theory is spontaneously broken while preserving the supersymmetry, the resulting theory has a massless superfield. One of its two bosonic degrees of freedom is the familiar phase rotation of the usual massless Nambu-Goldstone boson, but the other is a scale transformation. An indeterminate mass scale