April 2001 arXiv papers — page 5

Özgür E. Müstecaplıoğlu, L. You

We investigate the role of non-uniform spatial density profiles of trapped atomic Bose-Einstein condensates in the propagation of Raman-matched laser pulses under conditions for electromagnetically induced transparency (EIT). We find that the sharp edged axial density profile of an interacting condensate (due to a balance between external trap and repulsive

Antonio S. de Castro

The purpose of this comment is to clarify two points related to the Dirac equation. First, the Lorentz structure of the potential and its connection with the Klein paradox. Second, the connection between the number of space dimensions and the number of spinor components.

Daniel I. Fivel

It is shown that the quantum theory can be formulated on homogeneous spaces of generalized coherent states in a manner that accounts for interference, entanglement, and the linearity of dynamics without using the superposition principle. The coherent state labels, which are essentially instructions for preparing states, make it unnecessary to identify proper

Ralf Schützhold, Günter Plunien, Gerhard Soff

Alternative to the sonic black hole analogues we discuss a different scenario for modeling the Schwarzschild geometry in a laboratory - the dielectric black hole. The dielectric analogue of the horizon occurs if the velocity of the medium with a finite permittivity exceeds the speed of light in that medium. The relevance for experimental tests of the Hawking

Hong Qian

A comprehensive, semi-quantitative model for the thermodynamics of hydrophobic solvation is presented. The model is based on a very simple premise suggested by the scaled particle theory and treats both solute and solvent molecules as hard spheres. A connection between the peculiarly large heat-capacity change for hydrophobic solvation and the large temperat

N. A. Inogamov, M. Tricottet, A. M. Oparin, S. Bouquet

We study the 3D topology of Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) single-modes, which includes bubbles, jets and saddle points. We present an analytic description of the interface as a whole, for arbitrary time-dependant acceleration g(t). The dependance of morphology on the lattice - Hexagonal, square or triangular -of bubbles are investigated. RM

B. Guizal, D. Felbacq

A method is presented to investigate diffraction of an electromagnetic plane wave by an infinitely thin infinitely conducting circular cylinder with longitudinal slots. It is based on the use of the combined boundary conditions method that consists on expressing the continuity of the tangential components of both the electric and the magnetic fields in a sin

Shung-ichi Ando, Harold W. Fearing, Dong-Pil Min

We discuss the measurement of polarized photons arising from radiative muon capture. The spectrum of left circularly polarized photons or equivalently the circular polarization of the photons emitted in radiative muon capture on hydrogen is quite sensitive to the strength of the induced pseudoscalar coupling constant $g_P$. A measurement of either of these q

B. K. Agrawal, Tapas Sil, S. K. Samaddar, J. N. De

The thermal evolution of the shell correction energy is investigated for deformed nuclei using Strutinsky prescription in a self-consistent relativistic mean-field framework. For temperature independent single-particle states corresponding to either spherical or deformed nuclear shapes, the shell correction energy $Δ_{sc}$ steadily washes out with temperatur

Pablo Yepes

The CMS detector is well equipped to provide unique measurements in heavy ion collisions at LHC. It will provide measurements of the J/Psi and Upsilon families with good separation of the different resonances. Jet quenching will be studied by analyzing monojet-to-dijet ratios and Z0(gamma)+jet events.

C. Pinkenburg

The E895 experiment at the AGS measured strange particle production and collective behavior in Au+Au collisions between 2--8 AGeV. The production of $Λ$ Baryons and K$^0$ Mesons as function of energy rises smoothly and exhibits a nonlinear impact parameter dependence. Neutral and positively charged Kaons exhibit a strong anti-flow behavior. $Λ$ Baryons show

M. D'Agostino, R. Bougault, F. Gulminelli, M. Bruno

A global protocol for the thermostatistical analysis of hot nuclear sources is discussed. Within our method of minimization of variances we show that the abnormal kinetic energy fluctuation signal recently reported in different experimental data (M.D'Agostino et al.-Phys. Lett. B 473 (2000) 219, N. Le Neindre et al.- contr. to the XXXVIII Bormio Winter M

A. Maj, M. Kmiecik, W. Krolas, J. Styczen

The possible existence of Jacobi shape transition in hot 46Ti at high angular momenta was investigated with the Giant Dipole Resonance exclusive experiments. The GDR spectra and the angular distributions are consistent with predictions of the thermal shape fluctuation model indicating elongated nuclear shapes.

A. Lima-Santos

We investigate the possible regular solutions of the boundary Yang-Baxter equation for the vertex models associated to the D_{n+1}^(2) affine Lie algebra. We have classified them in terms of three types of K-matrices. The first one have n+2 free parameters and all the matrix elements are non-null. The second solution is given by a block diagonal matrix with

Cristina Masoller, Damian H. Zanette

We study the synchronization of two chaotic maps with unidirectional (master-slave) coupling. Both maps have an intrinsic delay $n_1$, and coupling acts with a delay $n_2$. Depending on the sign of the difference $n_1-n_2$, the slave map can synchronize to a future or a past state of the master system. The stability properties of the synchronized state are s

Wen-Xiu Ma, Yunbo Zeng

In contrast to mono-constrained flows with N degrees of freedom, binary constrained flows of soliton equations, admitting 2x2 Lax matrices, have 2N degrees of freedom. By means of the existing method, Lax matrices only yield the first N pairs of canonical separated variables. An approach for constructing the second N pairs of canonical separated variables wi

Hiroaki Takagi, Kunihiko Kaneko

The replication and differentiation of spots in reaction diffusion equations are studied by extending the Gray-Scott model with self-replicating spots to include many degrees of freedom needed to model systems with many chemicals. By examining many possible reaction networks, the behavior of this model is categorized into three types: replication of homogene

Kristin Lauter, Jean-Pierre Serre

Currently, the best upper bounds on the number of rational points on an absolutely irreducible, smooth, projective algebraic curve of genus g defined over a finite field F_q come either from Serre's refinement of the Weil bound if the genus is small compared to q, or from Oesterle's optimization of the explicit formulae method if the genus is large.

Xiang Fang

It's well known that the functional Hilbert space over the unit ball in $B_{d} \in C^d$, with kernel function $K(z,w)=\frac{1}{1-z_{1}w_{1}-... -z_{d}w_{d}}$, admits a natural $A(B_{d})$-module structure. We show the rank of a nonzero submodule is infinity if and only if the submodule is of infinite codimension. Together with Arveson's dilation theor

D. Schuetz

We use the one parameter fixed point theory of Geoghegan and Nicas to get information about the closed orbit structure of transverse gradient flows of closed 1-forms on a closed manifold M. We define a noncommutative zeta function in an object related to the first Hochschild homology group of the Novikov ring associated to the 1-form and relate it to the tor

A. I. Bobenko, T. Hoffmann, Yu. B. Suris

Hexagonal circle patterns are introduced, and a subclass thereof is studied in detail. It is characterized by the following property: For every circle the multi-ratio of its six intersection points with neighboring circles is equal to -1. The relation of such patterns with an integrable system on the regular triangular lattice is established. A kind of a B&#

Alexander Kirillov

In this paper, we try to answer the following question: given a modular tensor category $\A$ with an action of a compact group $G$, is it possible to describe in a suitable sense the ``quotient'' category $\A/G$? We give a full answer in the case when $\A=\vec$ is the category of vector spaces; in this case, $\vec/G$ turns out to be the category of r

Sergey Fomin, Andrei Zelevinsky

A composition of birational maps given by Laurent polynomials need not be given by Laurent polynomials; however, sometimes---quite unexpectedly---it does. We suggest a unified treatment of this phenomenon, which covers a large class of applications. In particular, we settle in the affirmative a conjecture of D$.$Gale and R$.$Robinson on integrality of genera

Morten Brun

In this paper we examine certain filtrations of topological Hochschild homology and topological cyclic homology. As an example we show how the filtration with respect to a nilpotent ideal gives rise to an analog of a theorem of Goodwillie saying that rationally relative K-theory and relative cyclic homology agree. Our variation says that the p-torsion parts

L. P. Bos, A. Brudnyi, N. Levenberg

We show that on the curves y=e^{t(x)} where t(x) is a fixed polynomial, there holds a tangential Markov inequality of exponent four. Specifically, for the real interval [a,b] there is a constant C such that max_{x\in [a,b]}|\frac{d}{dx}P(x,e^{t(x)})|\leq C(deg(P))^{4} max_{x\in [a,b]}|P(x,e^{t(x)})| for all bivariate polynomials P(x,y).

Anton I. Iliev

In this paper a new method which is a generalization of the Ehrlich-Kjurkchiev method is developed. The method allows to find simultaneously all roots of the algebraic equation in the case when the roots are supposed to be multiple with known multiplicities. The offered generalization does not demand calculation of derivatives of order higher than first simu

A. I. Iliev

In this paper methods for simultaneous finding all roots of generalized polynomials are developed. These methods are related to the case when the roots are multiple. They possess cubic rate of convergence and they are as labour-consuming as the known methods related to the case of polynomials with simple roots only.

Manfred Peter

An explicit product representation is proved for the correlation function of the multiplicities of closed geodesics on the modular surface. This makes rigorous part of the investigation of Bogomolny, Leyvraz and Schmit on the correlation of the eigenvalues of the Laplacian on the modular surface. The result can also be seen as a (rigorously proved) analogue

V. Ovsienko, P. Redou

Let ${\cal F}_λ$ be the space of tensor densities on ${\bf R}^n$ of degree $λ$ (or, equivalently, of conformal densities of degree $-λn$) considered as a module over the Lie algebra $so(p+1,q+1)$. We classify $so(p+1,q+1)$-invariant bilinear differential operators from ${\cal F}_λ\otimes{\cal F}_μ$ to~${\cal F}_ν$. The classification of linear $so(p+1,q+1)$-

Kota Yoshioka

In this paper, we consider moduli spaces of stable sheaves on abelian surfaces. Our main assumption is the primitivity of the associated Mukai vector. We construct many isomorphisms of muduli spaces induced by Fourier-Mukai functor. As an application, we show that deformation type of these spaces are determined by their dimension. We next show that the fiber

Conor J. Houghton, Steffen Krusch

There are only three stable singularities of a differentiable map between three-dimensional manifolds, namely folds, cusps and swallowtails. A Skyrme configuration is a map from space to SU(2), and its singularities correspond to the points where the baryon density vanishes. In this paper we consider the singularity structure of Skyrme configurations. The Sk

Daniel F. Litim

We discuss an optimisation criterion for the exact renormalisation group based on the inverse effective propagator, which displays a gap. We show that a simple extremisation of the gap stabilises the flow, leading to better convergence of approximate solutions towards the physical theory. This improves the reliability of truncations, most relevant for any hi

Gerard 't Hooft

In deterministic theories, one can start from a set of ontological states to formulate the dynamical laws, but these may not be directly observable. Observable are only equivalence classes of states, and these will span a basis of "beables", to be promoted to an orthonormal basis of Hilbert Space. After transforming this basis to a more conventional

Luca Griguolo, Massimo Pietroni

We study the IR/UV connection of the four-dimensional non-commutative phi^4 theory by using the Wilsonian Renormalization Group equation. Extending the usual formulation to the non-commutative case we are able to prove UV renormalizability to all orders in perturbation theory. The full RG equations are finite in the IR, but perturbative approximations of the

H S Booth, G Legg, P D Jarvis

The Dirac equation for an electron in an external electromagnetic field can be regarded as a singular set of linear equations for the vector potential. Radford's method of algebraically solving for the vector potential is reviewed, with attention to the additional constraints arising from non-maximality of the rank. The extension of the method to general

Keith R. Dienes

In this paper, we propose a possible new approach towards solving the gauge hierarchy problem without supersymmetry and without extra spacetime dimensions. This approach relies on the finiteness of string theory and the conjectured stability of certain non-supersymmetric string vacua. One crucial ingredient in this approach is the idea of ``misaligned supers

C. B. Yang, X. Cai

The influence of pure statistical fluctuations on $K/π$ ratio is investigated in an event-by-event way. Poisson and the modified negative binomial distributions are used as the multiplicity distributions since they both have statistical background. It is shown that the distributions of the ratio in these cases are Gaussian, and the mean and relative variance

A. A. Henneman, Daniel Boer, P. J. Mulders

We use Lorentz invariance and the QCD equations of motion to study the evolution of functions that appear at leading order in a 1/Q expansion in azimuthal asymmetries. This includes the evolution equation of the Collins fragmentation function. The moments of these functions are matrix elements of known twist two and twist three operators. We present the evol

W. J. Murray

The prospects for a muon collider operated as a Higgs factory are reviewed. The large muon mass means that the s-channel Higgs production mechanism is available, and simultaneously suppresses bremsstrahlung so that the beam energy spread can be kept to the MeV level required to exploit this. Thus this is the only machine which can make a direct scan over the

S. R. Gevorkyan, S. S. Grigoryan

It is shown that the yield of relativistic positronium atoms in photoproduction on extended targets is much larger than usually accepted.The cause of such difference is transparent. At high energies, when the positronium atom formation time $τ_f$ becomes greater than the target length L, it is the free $e^+e^-$ pair that propagates through the target and the

D. Ebert, R. N. Faustov, V. O. Galkin, H. Toki

The exclusive rare radiative B meson decays to orbitally excited axial-vector mesons K_1^*(1270), K_1(1400) and to the tensor meson K_2^*(1430) are investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. These decays are considered without employing the heavy quark expansion for the s quark.

Naoyuki Akama, Yuichiro Kiyo, Shinji Komine, Takeo Moroi

CP violations in the kaon system are studied in supersymmetric SU(5) model with right-handed neutrinos. We pay a special attention to the renormalization group effect on the off-diagonal elements of the squark mass matrices. In particular, if the Yukawa couplings and mixings in the neutrino sector are sizable, off-diagonal elements of the right-handed down-t

C. A. Dominguez, A. Ramlakan, K. Schilcher

Laplace transform QCD sum rules for two-point functions related to the strangeness-changing scalar and pseudoscalar Green&#39;s functions $ψ(Q^2)$ and $ψ_5(Q^2)$, are used to determine the subtraction constants $ψ(0)$ and $ψ_5(0)$, which fix the ratio $R_{su}\equiv \frac{<\bar{s}s>}{<\bar{u}u>}$. Our results are $ψ(0)= - (1.06 \pm 0.21) \times 10^{-3} {GeV}^

B. Pötter, T. Schörner

We have implemented a systematic procedure for combining parton shower algorithms with next-to-leading order QCD calculations for the case of jet production in deep-inelastic electron-proton scattering. Using this method we have computed inclusive jet cross sections and jet shapes for the case of single-jet production and compared them to data from the ZEUS

Yeong Gyun Kim, Mihoko M. Nojiri

We investigate the implications of the recent measurement of muon anomalous magnetic moment for the direct detection of neutralino dark matter in the three different SUSY models: mSUGRA, a model with non-universal Higgs mass, and an SO(10) GUT model. We consider two extreme scenario for $Δa_μ$ bound, i.e. $27 \times 10^{-10} < Δa_μ< 59 \times 10^{-10}$ (1$σ$

S. Maedan

We show how parametric resonance mechanism follows quench mechanism in the classical linear sigma model. The parametric resonance amplifies long wavelength modes of the pion for more than $10 fm/c$. The shifting from the quench mechanism to the parametric resonance mechanism is described by a time dependent quantity. After the quench mechanism is over, that

Rula Tabbash

We comment briefly on some of the advantages and disadvantages of compact hyperbolic manifolds as candidate manifolds for large radii compactifications.

Roberto Frezzotti, Stefan Sint, Peter Weisz

Lattice QCD with Wilson quarks and a chirally twisted mass term (tmQCD) has been introduced in refs. [1,2]. We here apply Symanzik's improvement programme to this theory and list the counterterms which arise at first order in the lattice spacing a. Based on the generalised transfer matrix, we define the tmQCD Schrodinger functional and use it to derive renor

P. Suranyi

Smeared Abelian and center gauges are introduced in pure non-Abelian lattice gauge theories. Popular Abelian and center gauges are limits of smeared gauges. Smeared gauges are also shown to be equivalent to Higgs theories. As a result, distributions and interactions of monopoles and vortices, which are objects responsible for confinement in pure gauge theori

Grahame A. Blair

The physics at a 500-800 GeV electron positron linear collider, TESLA, is reviewed. The machine parameters that impact directly on the physics are discussed and a few key performance goals for a detector at TESLA are given. Emphasis is placed on precision measurements in the Higgs and top sectors and on extrapolation to high energy scales in the supersymmetr

Giovanni Amelino-Camelia

I propose a phenomenological description of space-time foam and discuss the experimental limits that are within reach of forthcoming experiments.

Luc Blanchet

Contents: I. Introduction; II. Summary of optimal signal filtering; III. Newtonian binary polarization waveforms; IV. Newtonian orbital phase evolution; V. Post-Newtonian wave-generation; VI. Inspiral binary waveform.

Luc Blanchet

The post-Newtonian expansion appears to be a relevant tool for predicting the gravitational waveforms generated by some astrophysical systems such as binaries. In particular, inspiralling compact binaries are well-modelled by a system of two point-particles moving on a quasi-circular orbit whose decay by emission of gravitational radiation is described by a

Abel Camacho, Abel Camacho-Galvan

In this work we obtain a nondemolition variable for the case in which a charged particle moves in the electric and gravitational fields of a spherical body. Afterwards we consider the continuous monitoring of this nondemolition parameter, and calculate along the ideas of the so called restricted path integral formalism, the corresponding propagator. Using th

Thibault Damour

The transition between (non supersymmetric) quantum string states and Schwarzschild black holes is discussed. This transition occurs when the string coupling $g^2$ (which determines Newton&#39;s constant) increases beyond a certain critical value $g_c^2$. We review a calculation showing that self-gravity causes a typical string state of mass $M$ to shrink, a

Florian Siebel, Peter Huebner

In Brodbeck et al 1999 it has been shown that the linearised time evolution equations of general relativity can be extended to a system whose solutions asymptotically approach solutions of the constraints. In this paper we extend the non-linear equations in similar ways and investigate the effect of various possibilities by numerical means. Although we were

V. Bashkov, M. Malakhaltsev

We find equations of particle motion from the point of view of observer on a rotating disk, and demonstrate that a particle moving along a rotating disk is influenced by forces arising from geometry. They can be considered as analogs of the centrifugal forces and the Coriolis forces.

Jeroen van den Brink, Peter Horsch, Andrzej M. Oles

We investigate the spectral function of a hole moving in the orbital-ordered ferromagnetic planes of LaMnO$_3$, and show that it depends critically on the type of orbital ordering. While the hole does not couple to the spin excitations, it interacts strongly with the excitations of $e_g$ orbitals (orbitons), leading to new type of quasiparticles with a dispe

Yu. A. Kuznetsov, E. G. Timoshenko

Using the Gaussian Ansatz for the monomer-monomer correlation functions we derive a set of the self-consistent equations for determination of the conformational state in the bead-and-spring copolymer model. The latter is based on the Edwards type effective free energy functional with arbitrary two-body interaction matrix. The rate of conformational changes i

M. A. Tanatar, M. Suzuki, S. Nagai, Z. Q. Mao

The dependence of in-plane and interplane thermal conductivities of Sr2RuO4 on temperature, as well as magnetic field strength and orientation, is reported. We found no notable anisotropy in the thermal conductivity for the magnetic field rotation parallel to the conducting plane in the whole range of experimental temperatures and fields, except in the vicin

J. Ledieu, R. McGrath, R. D. Diehl, T. A. Lograsso

The nature of the five-fold surface of Al(70)Pd(21)Mn(9) has been investigated using scanning tunneling microscopy. From high resolution images of the terraces, a tiling of the surface has been constructed using pentagonal prototiles. This tiling matches the bulk model of Boudard et. al. (J. Phys.: Cond. Matter 4, 10149, (1992)), which allows us to elucidate

S. Tsuda, T. Yokoya, T. Kiss, Y. Takano

We study the new binary intermetallic superconductor MgB2 using high-resolution photo-emission spectroscopy. The superconducting-state spectrum measured at 5.4 K shows a coherent peak with a shoulder structure, in sharp contrast to that expected from a simple isotropic-gap opening. The spectrum can be well reproduced using the weighted sum of two Dynes funct

Didier Felbacq

This comment concerns the homogenization of 2D dielectric photonic crystals, and the fact that the limits $k\to 0$ ($k$ is the Bloch vector) and $ε\to +\infty $ do not commute for $p$-polarized waves

N. Majd, A. Aghamohammadi, M. Khorrami

An asymmetric generalization of the zero-temperature q-state Potts model on a one dimensional lattice, with and without boundaries, has been studied. The dynamics of the particle number, and specially the large time behavior of the system has been analyzed. In the thermodynamic limit, the system exhibits two kinds of phase transitions, a static and a dynamic

Tetsuya Hamano, Yoshiyuki Ono

We discuss the ground state of a two dimensional electron-lattice system described by a Su-Schrieffer-Heeger type Hamiltonian with a half-filled electronic band, for which it has been pointed out in the previous paper [J. Phys. Soc. Jpn. 69 (2000) 1769-1776] that the ground state distortion pattern is not unique in spite of a unique electronic energy spectru

Hildegard Meyer-Ortmanns

We derive catastrophic senescence of the Pacific salmon from an aging model which was recently proposed by Stauffer. The model is based on the postulates of a minimum reproduction age and a maximal genetic lifespan. It allows for self-organization of a typical age of first reproduction and a typical age of death. Our Monte Carlo simulations of the population

D. Fay, M. Weger

We investigate the effect of an incipient ferrolectric transition on vertex corrections to the superconducting pairing interaction. The vertex corrections for small momentum transfers are large independent of the type of Boson responsible for the superconducting transition. The electron-phonon interaction is found to be enhanced by a nearly ferroelectric med

Manabu Takahashi, Jun-ichi Igarashi

We investigate the mechanism of the resonant X-ray scattering on the Ti $K$ edge region of YTiO$_3$ using the band structure calculation combined with the local density approximation. A large intensity is obtained for the orbital superlattice spots. The calculated spectra consist of several peaks as a function of photon energy in agreement with the recent ex

D. Kaczorowski, J. Klamut, A. J. Zaleski

Short discussion trying to explain, why superconductivity revealed for some diborides is not always confirmed in experiments of different research groups.

Bao-Qing Ma, Song Gao, Gang Su, Guang-Xian Xu

Cyano-bridged bimetallic hybrid Prussian Blue one- to three-dimensional (1D-3D) coordination polymers based on [M(CN)6]3- (M = Fe, Cr, Mn) have attracted great attention because of their rich and interesting structures and magnetic behaviors. The previous study implies that increasing dimensionality may enhance and improve bulk magnetic properties.Our strate

Keith A. Williams, Bhabendra K. Pradhan, Peter C. Eklund, Milen K. Kostov

We have observed the S- and Q-branch Raman spectra of H2, HD, and D2 adsorbed at 85K and pressures up to 8 atm on single-walled, carbon nanotubes (SWNT). Comparative data for H2 on graphite and C60 were also collected. For each adsorbate, we observed a small shift in the Q-branch frequencies relative to the gas-phase values. To aid in interpreting this resul

Song Gao, Gang Su, Tao Yi, Bao-Qing Ma

An unusual field dependent slow magnetic relaxation and two distinct transitions were observed in a family of new rare earth-transition metal complexes, [Ln (bipy) (H$_{2}$O)$_{4}$ M(CN)$_{6}$] $\cdot $1.5 (bipy) $ \cdot $ 4H$_{2}$O (bipy = 2,2&#39;-bipyridine; Ln = Gd$^{3+}$,Y$^{3+}$; M = Fe$ ^{3+}$, Co$^{3+}$). The novel magnetic relaxation, which is quite

B. Jancovici, L. Šamaj

Classical Coulomb systems at equilibrium, bounded by a plane dielectric wall, are studied. A general two-point charge correlation function is considered. Valid for any fixed position of one of the points, a new relation is found between the algebraic tail of the correlation function along the wall and the dipole moment of that function. The relation is teste

Umit Ozgur, Chang-Won Lee, Henry O. Everitt

Using sub-picosecond optical pump-probe techniques, coherent zone-folded longitudinal acoustic phonons (ZFLAPs) were generated and controlled in an InGaN multiple quantum well structure. A one-pump, one-probe differential transmission technique revealed that carriers injected near the barrier band edge were quickly captured into the quantum wells and generat

Marc Davis, Jeffrey Newman

Since the late 1970&#39;s, redshift surveys have been vital for progress in understanding large-scale structure in the Universe. The original CfA redshift survey collected spectra of 20-30 galaxies per clear night on a 1.5 meter telescope; over a two year period the project added ~2000 new redshifts to the literature. Subsequent low-z redshift surveys have b

A. Del Popolo

I discuss the effect of non-radial motions on the small-scale pairwise peculiar velocity dispersions of galaxies (PVD) in a CDM model. I calculate the PVD for the SCDM model by means of the refined cosmic virial theorem (CVT) (Suto & Jing 1997) and taking account of non-radial motions by means of Del Popolo & Gambera (1998) model. I compare the results of th

S. B. Charnley, S. D. Rodgers, Y-J. Kuan, H-C. Huang

We review recent studies of organic molecule formation in dense molecular clouds and in comets. We summarise the known organic inventories of molecular clouds and recent comets, particularly Hale-Bopp. The principal chemical formation pathways involving gas phase reactions, as well as formation by catalytic reactions on grain surfaces or through dust fragmen

S. D. Rodgers, S. B. Charnley

We show analytically that large abundances of NH2D and NHD2 can be produced by gas phase chemistry in the interiors of cold dense clouds. The calculated fractionation ratios are in good agreement with the values that have been previously determined in L134N and suggest that triply-deuterated ammonia could be detectable in dark clouds. Grain surface reactions

Prasenjit Saha, Liliya L. R. Williams

We explain how an approximation to the rings formed by the host galaxies in lensed QSOs can be inferred from the QSO data alone. A simple ring image can be made from any lens model by a simple piece of computer graphics: just plot a contour map of the arrival-time surface with closely-spaced contours. We go on to explain that rings should be (a) sensitive to

L. M. Oskinova, R. Ignace, J. C. Brown, J. P. Cassinelli

We describe X-ray production in the atmospheres of hot, early-type stars in the framework of a ``stochastic shock model&#39;&#39;. The extended envelope of a star is assumed to possess numerous X-ray emitting ``hot&#39;&#39; zones that are produced by shocks and embedded in the ambient ``cold&#39;&#39; medium in dynamical equilibrium. It is shown that the ap

D. Pourbaix, F. Arenou

The combination of Hipparcos astrometric data with the spectroscopic data of putative extrasolar planets seems to indicate that a significant fraction of these low-mass companions could be brown or M dwarfs Han et al. (2001). We show that this is due to the adopted reduction procedure, and consequently that the Hipparcos data do not reject the planetary mass

S. M. Harun-or-Rashid, M. Roos

We undertake a critical evaluation of recent observational information on $Ω_m$ and $Ω_Λ$ in order to identify possible sources of systematic errors and effects of simplified statistical analyses. We combine observations for which the results have been published in the form of likelihood contours in the $Ω_m ,Ω_Λ$ plane. We approximate the contours by fifth

B. Fuchs

The problem of dynamical heating of galactic discs by spiral density waves is discussed using the shearing sheet model. The secular evolution of the disc is described quantitatively by a diffusion equation for the distribution function of stars in the space spanned by integrals of motion of the stars, in particular the radial action integral and an integral

Masaru Shibata, Koji Uryu

We perform 3D numerical simulations for merger of equal mass binary neutron stars in full general relativity preparing irrotational binary neutron stars in a quasiequilibrium state as initial conditions. Simulations have been carried out for a wide range of stiffness of equations of state and compactness of neutron stars, paying particular attention to the f

Masaru Shibata, Stuart L. Shapiro, Koji Uryu

We investigate the equilibrium and stability of supermassive stars of mass $M \agt 10^5M_{\odot}$ in binary systems. We find that corotating binaries are secularly unstable for close, circular orbits with $r \alt 4R(M/10^6M_{\odot})^{1/6}$ where $r$ is the orbital separation and $R$ the stellar radius. We also show that corotation cannot be achieved for dist

Niruj R. Mohan, K. R. Anantharamaiah, W. M. Goss

We have detected the H92alpha radio recombination line from two dwarf starburst galaxies, NGC 5253 and He 2-10, using the Very Large Array. Both the line data as well as the radio continuum data are used to model the properties of the ionized gas in the centers of these galaxies. We consider a multi-density model for radio recombination lines and show why pr

Maurizio Salaris, Achim Weiss

We have computed a grid of up-to-date stellar evolutionary models including atomic diffusion, in order to study the evolution with time of the surface Li abundance in low-mass metal-poor stars. We discuss in detail the dependence of the surface Li evolution on the initial metallicity and stellar mass, and compare the abundances obtained from our models with

Young-Wook Lee, Suk-Jin Yoon, Soo-Chang Rey, Brian Chaboyer

We present our recent revision of model constructions for the horizontal-branch (HB) morphology of globular clusters, which suggests the HB morphology is more sensitive to age compared to our earlier models. We also present our high precision CCD photometry for the classic second parameter pair M3 and M13. The relative age dating based on this photometry ind

S. C. Trager, S. M. Faber, A. Dressler

We review current progress in the study of the stellar populations of early-type galaxies, both locally and at intermediate redshifts. In particular, we focus on the ages of these galaxies and their evolution in hopes of determining the star formation epochs of their stars. Due to serious remaining systematic uncertainties, we are unable to constrain these e

Hsiao-Wen Chen, Kenneth M. Lanzetta, John K. Webb

(Abridged) We report the discovery of extended CIV gaseous envelopes around galaxies of a wide range of luminosity and morphological type. First, we show that CIV absorption systems are strongly clustered around galaxies on velocity scales of v < 250 km/s and impact parameter scales of rho < 100 h^{-1} kpc but not on larger velocity or impact parameter scale

S. Gordon, B. Koribalski, K. Jones

We present the results of new radio interferometer HI line observations for the merging galaxy pair NGC 4038/9 (`The Antennae&#39;), obtained using the Australia Telescope Compact Array. The results improve substantially on those of van der Hulst (1979) and show in detail the two merging galactic disks and the two tidal tails produced by their interaction. T

E. Rericha, C. Bizon, M. D. Shattuck, H. L. Swinney

We measure time-averaged velocity, density, and temperature fields for steady granular flow past a wedge and calculate a speed of granular pressure disturbances (sound speed) equal to 10% of the flow speed. The flow is supersonic, forming shocks nearly identical to those in a supersonic gas. Molecular dynamics simulations of Newton&#39;s laws and Monte Carlo

D. Rusin, D. R. Marlow, M. Norbury, I. W. A. Browne

We report the discovery of a new two-image gravitational lens system from the Cosmic Lens All-Sky Survey, CLASS B2319+051. Radio imaging with the Very Large Array (VLA) and Multi-Element Radio-Linked Interferometer Network (MERLIN) shows two compact components with a flux density ratio of 5:1, separated by 1.36 arcsec. Observations with the Very Long Baselin

Stephen Godfrey, Jonathan L. Rosner

The rates for magnetic dipole (M1) transitions $Υ(nS) \to η_b(n&#39;S) + γ$, $n&#39; \le n$, are compared. The photon energies for allowed ($n&#39; = n$) M1 transitions are very small, so hindered ($n&#39; < n$) transitions could be more favorable for discovering the $η_b(1S,2S)$. The question then arises whether $Υ(2S)$ or $Υ(3S)$ is a better source of $η_b

W. C. Wu, R. Joynt

Recent experiments make it appear more likely that the order parameter of the unconventional superconductor Sr$_2$RuO$_4$ has a spin-triplet $f$-wave symmetry. We study ultrasonic absorption and thermal conductivity of superconducting Sr$_2$RuO$_4$ and fit to the recent data for various $f$-wave candidates. It is shown that only $f_{x^2-y^2}$-wave symmetry c

Aaron W. Tustin, Margaret J. Geller, Scott J. Kenyon, Antonaldo Diaferio

We discuss H-band (1.65 micrometer) near-infrared photometry of the central 3x3h^{-2} Mpc^2 of Abell 1644 to a limiting M_H~M^*_H+3 (throughout this paper H_0=100 h km s^{-1} Mpc^{-1}). There are 861 galaxies in the photometric survey region. We also measured radial velocities of 155 galaxies; 141 of these are cluster members within 2.44 h^{-1} Mpc of the cl

Denes Molnar, Miklos Gyulassy

Differential elliptic flow and particle spectra are calculated taking into account the finite transport opacity of the gluon plasma produced in Au+Au at Ecm ~ 130 A GeV at RHIC. Covariant numerical solutions of the ultrarelativistic Boltzmann equation are obtained using the MPC parton cascade technique. For typical pQCD (~3 mb) elastic cross sections, extrem

Rudy Wijnands, Jon M. Miller, Michiel van der Klis

We report on several pointed Rossi X-ray Timing Explorer observations of the enigmatic low-mass X-ray binary (LMXB) 4U 1957+11 at different X-ray luminosities. The luminosity of the source varied by more than a factor of four on time scales of months to years. The spectrum of the source tends to get harder when its luminosity increases. Only very weak (1%-2%

Jeff Viaclovsky

We prove estimates and existence results for some fully nonlinear elliptic equations on Riemannian manifolds. These equations are not arbitrary, but arise naturally in the study of conformal geometry.

Lev I. Deych, A. A. Lisyansky, B. L. Altshuler

The variance of the Lyapunov exponent is calculated exactly in the one-dimensional Anderson model with random site energies distributed according to the Cauchy distribution. We derive an exact analytical criterion for the validity of the single parameter scaling in this model. According to this criterion, states with energies from the conduction band of the