March 2000 arXiv papers — page 7

Sunil Mukhi, Nemani V. Suryanarayana

We describe a tachyon-free stable non-BPS brane configuration in type IIA string theory. The configuration is an elliptic model involving rotated NS5 branes, D4 branes and anti-D4 branes, and is dual to a fractional brane-antibrane pair placed at a conifold singularity. This configuration exhibits an interesting behaviour as we vary the radius of the compact

D. Saller, R. Vitolo

In the framework of Galilei classical mechanics (i.e., general relativistic classical mechanics on a spacetime with absolute time) developed by Jadczyk and Modugno, we analyse systematically the relations between symmetries of the geometric objects. We show that the (holonomic) infinitesimal symmetries of the cosymplectic structure on spacetime and of its po

Wayne Hu, Rennan Barkana, Andrei Gruzinov

Cold dark matter (CDM) models predict small-scale structure in excess of observations of the cores and abundance of dwarf galaxies. These problems might be solved, and the virtues of CDM models retained, even without postulating {\it ad hoc} dark matter particle or field interactions, if the dark matter is composed of ultra-light scalar particles (m ~ 10^{-2

M. Fortunato, G. Harel, G. Kurizki

We show that conditional measurements on atoms following their interaction with a resonant cavity field mode can be used to effectively counter the decoherence of Fock-state superpositions due to cavity leakage.

Giovanni Modugno, Michele Modugno

We propose an experiment to look for possible small violations of the symmetrization postulate of Quantum Mechanics, in systems composed by three identical particles. Such violations could be detected by investigating the population of particular roto-vibrational states of symmetrical molecules containing three identical nuclei. We discuss the symmetry prope

Dominik Janzing, Thomas Beth

We show that every density matrix of an n-particle system prepared by a quantum network of constant depth is asymptotically commuting with the mean-field observables. We introduce certain pairs of hypersurfaces in the space of density matrices and give lower bounds for the depth of a network which prepares states lying outside those pairs. The measurement of

V. SunilKumar, B. A. Bambah, R. Jagannathan, P. K. Panigrahi

We present a general unified approach for finding the coherent states of polynomially deformed algebras such as the quadratic and Higgs algebras, which are relevant for various multiphoton processes in quantum optics. We give a general procedure to map these deformed algebras to appropriate Lie algebras. This is used, for the non compact cases, to obtain the

Ramandeep S. Johal

We address the problem of phase shift operator acting as time evolution operator in Pegg-Barnett formalism. It is argued that standard shift operator is inconsistent with the behaviour of the state vector under cyclic evolution. We consider a generally deformed oscillator algebra at q-root of unity, as it yields the same Pegg-Barnett operator and show that s

Xijia Miao

Any quantum computational network can be constructed with a sequence of the two-qubit diagonal quantum gates and one-qubit gates in two-state quantum systems. The universal construction of these quantum gates in the quantum systems and of the quantum computational networks with these gates may be achieved with the help of the operator algebra structure of Ha

L. F. Canto, R. Donangelo, M. S. Hussein

It is pointed out that the cross section for the scattering of identical charged bosons is isotropic over a broad angular range around 90 degrees when the Sommerfeld parameter has a critical value, which depends exclusively on the spin of the particle. A discussion of systems where this phenomenon can be observed is presented.

Kirk T. McDonald, Konstantine Shmakov

A free electron can temporarily gain a very significant amount of energy if it is overrun by an intense electromagnetic wave. In principle, this process would permit large enhancements in the center-of-mass energy of electron-electron, electron-positron and electron-photon interactions if these take place in the presence of an intense laser beam. Practical c

F. Calvo, J. P. Neirotti, David L. Freeman, J. D. Doll

We study the 38-atom Lennard-Jones cluster with parallel tempering Monte Carlo methods in the microcanonical and molecular dynamics ensembles. A new Monte Carlo algorithm is presented that samples rigorously the molecular dynamics ensemble for a system at constant total energy, linear and angular momenta. By combining the parallel tempering technique with mo

Alex Kaivarainen

1. Protein domain mesoscopic organization 2. Quantum background of lipid domain organization in biomembranes 3. Hierarchic approach to theory of solutions and colloid systems 4. Distant solvent-mediated interaction between macromolecules 5. Spatial self-organization in the water-macromolecular systems 6. Properties of [bisolvent - polymer system] 7. Osmosis

Alex Kaivarainen

1: New approach to theory of light refraction 1.1. Refraction in gas; 1.2. Light refraction in liquids and solids 2: Mesoscopic theory of Brillouin light scattering 2.1. Traditional approach; 2.2. Fine structure of scattering; 2.3. Mesoscopic approach; 2.4. Quantitative verification of hierarchic theory of Brillouin scattering 3: Mesoscopic theory of Mossbau

M. Conte, M. Ferro, G. Gemme, W. W. MacKay

The general expression of the Stern-Gerlach force is deduced for a charged particle, endowed with a magnetic moment, which travels inside a time varying magnetic field. Then, the energy integral of the Stern-Gerlach force is evaluated in the case of a particle crossing a TE rf cavity with its magnetic moment oriented in different ways with respect as the cav

J. P. Neirotti, F. Calvo, David L. Freeman, J. D. Doll

The heat capacity and isomer distributions of the 38 atom Lennard-Jones cluster have been calculated in the canonical ensemble using parallel tempering Monte Carlo methods. A distinct region of temperature is identified that corresponds to equilibrium between the global minimum structure and the icosahedral basin of structures. This region of temperatures oc

J-L. Ballot, M. Ericson, M. R. Robilotta

We study the changes produced by the deuteron on the QCD quark condensate by means the Feynman-Hellmann theorem and find that the pion mass dependence of the pion-nucleon coupling could play an important role. We also discuss the relation between the many body effect of the condensate and the meson exchange currents, as seen by photons and pions. For pion pr

A. Kievsky, C. R. Brune, M. Viviani

The total cross section for p-d breakup is studied in terms of the elastic S-matrix through the unitary condition. Calculations using the complex Kohn variational method along with the Pair Correlated Hyperspherical Harmonic basis are presented. The results have been restricted to energies below Ep=30 MeV where Coulomb effects are expected to be sizable and

Thomas Rupp, Hans A. Weidenmueller, Jean Richert

We use random-matrix theory and supersymmetry techniques to work out the two-point correlation function between states in a hierarchical model which employs Feshbach's chaining hypothesis: Classes of many-body states are introduced. Only states within the same or neighboring classes are coupled. We assume that the density of states per class grows monoto

Nikolay Minkov, S. B. Drenska, P. P. Raychev, R. P. Roussev

We derive analytic expressions for the energies and $B(E2)$-transition probabilities in the states of the ground and $γ$ bands of heavy deformed nuclei within a collective Vector-Boson Model with SU(3) dynamical symmetry. On this basis we examine the analytic behavior of the SU(3) energy splitting and the B(E2) interband transition ratios in the SU(3) contra

Horacio G. Rotstein, Amy Novick-Cohen, Rina Tannenbaum

The physical and chemical properties of metal nanoparticles differ significantly from those of free metal atoms as well as from the properties of bulk metals, and therefore, they may be viewed as a transition regime between the two physical states. Within this nanosize regime, there is a wide fluctuation of properties, particularly chemical reactivity, as a

Marko Robnik, Valery Romanovski

In the present paper we study the structure of the WKB series for the polynomial potential $V(x)=x^N$ ($N$ even). In particular, we obtain relatively simple recurrence formula of the coefficients $\s'_k$ of the semiclassical approximation and of the WKB terms for the energy eigenvalues.

Marko Vranicar, Marko Robnik

We analyse the accuracy of the approximate WKB quantization for the case of general one-dimensional quartic potential. In particular, we are interested in the validity of semiclassically predicted energy eigenvalues when approaching the limit $E\to \infty$, and in the accuracy of low lying energy levels below the potential barrier in the case of generally as

Marko Robnik, Luca Salasnich, Marko Vranicar

The accuracy of the WKB approximation when predicting the energy splitting of bound states in a double well potential is the main subject of this paper. The splitting of almost degenerate energy levels below the top of the barrier results from the tunneling and is thus supposed to be exponentially small. By using the standard WKB quantization we deduce an an

Marko Robnik, Gregor Veble

In this work we present the results of a study of spectral statistics for a classically integrable system, namely the rectangle billiard. We show that the spectral statistics are indeed Poissonian in the semiclassical limit for almost all such systems, the exceptions being the atypical rectangles with rational squared ratio of its sides, and of course the en

G. W. Patrick

The system of four point vortices in the plane has relative equilibria that behave as composite particles, in the case where three of the vortices have strength $-Γ/3$ and one of the vortices has strength $Γ$. These relative equilibria occur at nongeneric momenta. The reduction of this system, at those momenta, by continuous and then discrete symmetries, cla

M. Modugno, C. Tejero Prieto, R. Vitolo

We compare the covariant formulation of Quantum Mechanics on a curved spacetime fibred on absolute time with the standard Geometric Quantisation.

Elliott H. Lieb, Jakob Yngvason

This paper is a non-technical, informal presentation of our theory of the second law of thermodynamics as a law that is independent of statistical mechanics and that is derivable solely from certain simple assumptions about adiabatic processes for macroscopic systems. It is not necessary to assume a-priori concepts such as "heat", "hot and cold&#

Andrea Maffei

Improvements in the exposition.

Richard Hain, David Reed

In this note we give geometric formulations and proofs of three results of S. Morita. These results relate certain two dimensional cohomology classes of various moduli spaces of curves. We also give a geometric interpretation of a fourth result of Morita. One motivation of this work is to facilitate the application of these results in our work (in preparatio

Anton Leykin

Let n and d be positive integers, let k be a field and let P(n,d;k) be the space of the polynomials in n variables of degree at most d with coefficients in k. Let B(n,d) be the set of the Bernstein-Sato polynomials of all polynomials in P(n,d;k) as k varies over all fields of characteristic 0. G. Lyubeznik proved that B(n,d) is a finite set and asked if, for

Hermann Pfitzner

An L-embedded Banach spaace is a Banach space which is complemented in its bidual such that the norm is additive between the two complementary parts. On such spaces we define a topology, called an abstract measure topology, which by known results coincides with the usual measure topology on preduals of finite von Neumann algebras (like $L_1([0,1])$). Though

Mikhail Grinenko

Let R be a Dedekind scheme, $ν$ its generic point, X and V del Pezzo surfaces of degree 1 over R that are Gorenstein Mori fiber spaces (as 3-folds germs over the ground field). We study birational maps $ϕ:X\dasharrow V$ over R which are isomorphisms over the generic point of R. We put down normal forms of such transformations (in suitable coordinates) and gi

Hermann Pfitzner

Let L_1 be the predual of a von Neumann algebra with a finite faithful normal trace. We show that a bounded sequence in L_1 converges to 0 in measure if and only if each of its subsequences admits another subsequence which converges to 0 in norm or spans $l^1$ "almost isometrically". Furthermore we give a quantitative version of an essentially known

Hermann Pfitzner

Nonreflexive Banach spaces that are complemented in their bidual by an L-projection - like preduals of von Neumann algebras or the Hardy space $H^1$ - contain, roughly speaking, many copies of $l^1$ which are very close to isometric copies. Such $l^1$-copies are known to fail the fixed point property. Similar dual results hold for $c_0$.

Lisa C. Jeffrey

The moduli space M(n,d) is an algebraic variety parametrizing those representations of the fundamental group of a punctured Riemann surface into the Lie group SU(n) for which a loop around the boundary is sent to the n-th root of unity exp (2 πi d/n) multiplied by the identity matrix. If n and d are coprime it is in fact a Kähler manifold. One may relax the

Wolfgang Buehring

For a second-order linear differential equation with two irregular singular points of rank three, multiple Laplace-type contour integral solutions are considered. An explicit formula in terms of the Stokes multipliers is derived for the characteristic exponent of the multiplicative solutions. The Stokes multipliers are represented by converging series with t

Christian Fronsdal

The problem is the classification of the ideals of ``free differential algebras", or the associated quotient algebras, the q-algebras; being finitely generated, unital C-algebras with homogeneous relations and a q-differential structure. This family of algebras includes the quantum groups, or at least those that are based on simple (super) Lie or Kac-Moo

K Koike, H Shiga, N Takayama, T Tsutsui

Let us consider the rank 14 lattice $P=D_4^3\oplus < -2> \oplus < 2>$. We define a K3 surface S of type P with the property that $P\subset {\rm Pic}(S) $, where ${\rm Pic}(S) $ indicates the Picard lattice of S. In this article we study the family of K3 surfaces of type P with a certain fixed multipolarization. We note the orthogonal complement of P in the K

Richard Hain

This is an informal set of lecture notes on moduli spaces of curves based on a set of lectures given at the ICTP last summer. It begins at an elementary level and discusses the genus 1 case in detail. The notes then give an informal treatement of Teichmuller space and higher genus moduli spaces. The point of view is generally topological and analytical.

Guo-Niu Han, Christian Krattenthaler

Let $x_1,x_2,...,x_n$ be the zeroes of a polynomial P(x) of degree n and $y_1,y_2,...,y_m$ be the zeroes of another polynomial Q(y) of degree m. Our object of study is the permanent $\per(1/(x_i-y_j))_{1\le i\le n, 1\le j\le m}$, here named &#34;Scott-type&#34; permanent, the case of $P(x)=x^n-1$ and $Q(y)=y^n+1$ having been considered by R. F. Scott. We pre

M. Chabab, R. Markazi, E. H. Saidi

Using the formal analogy between the Dick superstring inspired model of ref.[6] and the problem of building of Eguchi Hanson metric in 4d N=2 harmonic superspace (hs), we derive a general formula for the quark-quark interaction potential V(r) including the Dick confining potential. The interquark potential V(r) depends on the dilaton-gluon coupling and may b

A. Alonso Izquierdo, M. A. Gonzalez Leon, J. Mateos Guilarte

It is shown how a integrable mechanical system provides all the localized static solutions of a deformation of the linear O(N)-sigma model in two space-time dimensions. The proof is based on the Hamilton-Jacobi separability of the mechanical analogue system that follows when time-independent field configurations are being considered. In particular, we descri

F. Gieres, H. Nieder, T. Pisar, L. Popp

We study the gauge-fixing and symmetries (BRST-invariance and vector supersymmetry) of various six-dimensional topological models involving Abelian or non-Abelian 2-form potentials.

E. D&#39;Hoker, J. Erdmenger, D. Z. Freedman, M. Perez-Victoria

We study near-extremal n-point correlation functions of chiral primary operators, in which the maximal scale dimension k is related to the others by k=\sum_i k_i-m with m equal to or smaller than n-3. Through order g^2 in field theory, we show that these correlators are simple sums of terms each of which factors into products of lower-point correlators. Term

Gautam Mandal

We review some aspects of the D1/D5 system of type IIB string theory and the associated five dimensional black hole. We include a pedagogical discussion of the construction of relevant classical solutions in supergravity. We discuss the gauge theory and the conformal field theory relevant to D-brane description of these systems. In order to discuss Hawking r

David O. Caldwell

A neutrino mass-mixing scheme which successfully avoids the &#34;alpha effect,&#34; allowing r-process nucleosynthesis in the neutrino-heated ejecta of supernovae, quite independently requires the same parameters as the scheme which best fits all current indications for neutrino mass. The significance for particle physics is this independent evidence for (1)

Ren-Jie Zhang

I summarize results of two-loop effective potential calculations of the lightest CP-even Higgs boson mass in the minimal supersymmetric standard model.

Carlos L. Schat, Norberto N. Scoccola

We obtain the rotational spectrum of strange multibaryon states by performing the SU(3) collective coordinate quantization of the static multi-Skyrmions. These background configurations are given in terms of rational maps, which are very good approximations and share the same symmetries as the exact solutions. Thus, the allowed quantum numbers in the spectra

J. Nemchik

Within the color dipole gBFKL dynamics applied to the diffraction slope we predict an anomalous t dependence of the differential cross section as a function of energy and Q^2 for production of radially excited V&#39;(2S) light vector mesons in contradiction with a well known standard monotonous t- behaviour for V(1S) mesons. The origin of this phenomenon is

A. Bacchetta, S. Boffi, R. Jakob

We establish the relationship between distribution and fragmentation functions and the structure functions appearing in the cross section of polarized 1-particle inclusive deep-inelastic scattering. We present spectator model evaluations of these structure functions focusing on the case of an outgoing spin-1/2 baryon. Distribution functions obtained in the s

Noriaki Kitazawa, Nobuhito Maru, Nobuchika Okada

We present simple models of dynamical supersymmetry breaking with gauged U(1)_R symmetry. The minimal supersymmetric standard model and supersymmetric SU(5) GUT are considered as the visible sector. The anomaly cancellation conditions for U(1)_R are investigated in detail and simple solutions of the R-charge assignments are found. We show that this scenario

M. Czakon, J. Gluza

We examine single chargino production in conjunction with R-parity lepton number violation in future lepton-lepton collisions. Present bounds on R-parity violating couplings allow for a production cross section of the order of ${\cal{O}} (10 {fb})$ for a wide range of sneutrino and chargino masses. Scenarios of chargino decay which lead to purely leptonic si

D. Bakari, SLIM Collaboration

We propose to implement one passive nuclear track detector array of 400 m^2 at the Chacaltaya High Altitude Laboratory (5230 m a.s.l.). The main purposes of the experiment concern the searches for magnetic monopoles of relatively low masses at the Parker bound level, searches for low mass nuclearites and searches for some supersymmetric dark matter candidate

I. V. Vancea

We use the duality between the local Cartezian coordinates and the solutions of the Klein-Gordon equation to parametrize locally the spacetime in terms of wave functions and prepotentials. The components of metric, metric connection, curvature as well as the Einstein equation are given in this parametrization. We also discuss the local duality between coordi

Ion I. Cotăescu, Ion I. Cotăescu

The quantum modes of a new family of relativistic oscillators are studied by using the supersymmetry and shape invariance in a version suitable for (1+1) dimensional relativistic systems. In this way one obtains the Rodrigues formulas of the normalized energy eigenfunctions of the discrete spectra and the corresponding rising and lowering operators. Pacs: 04

V. Aldaya, J. L. Jaramillo

A model for 2D-quantum gravity from the Virasoro symmetry is studied. The notion of space-time naturally arises as a homogeneous space associated with the kinematical (non-dynamical) SL(2,R) symmetry in the kernel of the Lie-algebra central extension for the critical values of the conformal anomaly. The rest of the generators in the group, L_n (n>1, n<-1), m

Uwe Muench, Friedrich W. Hehl, Bahram Mashhoon

We discuss two nonlocal models of electrodynamics in which the nonlocality is induced by the acceleration of the observer. Such an observer actually measures an electromagnetic field that exhibits persistent memory effects. We compare Mashhoon&#39;s model with a new ansatz developed here in the framework of charge & flux electrodynamics with a constitutive l

Anatoly D. Plotnikov

We examine the Maximum Independent Set Problem in an undirected graph. The main result is that this problem can be considered as the solving the same problem in a subclass of the weighted normal twin-orthogonal graphs. The problem is formulated which is dual to the problem above. It is shown that, for trivial twin-orthogonal graphs, any of its maximal indepe

Deborah East, Miroslaw Truszczynski

Answer-set programming (ASP) has emerged recently as a viable programming paradigm well attuned to search problems in AI, constraint satisfaction and combinatorics. Propositional logic is, arguably, the simplest ASP system with an intuitive semantics supporting direct modeling of problem constraints. However, for some applications, especially those requiring

O. Bleibaum, H. Böttger, V. V. Bryksin, A. N. Samukhin

A new method for investigating relaxation phenomena for charge carriers hopping between localized tail states has been developed. It allows us to consider both charge and energy {\it dispersive} transport. The method is based on the idea of quasi-elasticity: the typical energy loss during a hop is much less than all other characteristic energies. We have inv

M. R. Norman, M. Randeria, B. Janko, J. C. Campuzano

The condensation energy can be shown to be a moment of the change in the occupied part of the spectral function when going from the normal to the superconducting state. As a consequence, there is a one to one correspondence between the energy gain associated with forming the superconducting ground state, and the dramatic changes seen in angle resolved photoe

J. P Eisenstein, M. P. Lilly, K. B. Cooper, L. N. Pfeiffer

A brief summary of the emerging evidence for a new class of collective states of two-dimensional electrons in partially occupied excited Landau levels is presented. Among the most dramatic phenomena described are the large anisotropies of the resistivity observed at very low temperatures near half-filling of the third and higher Landau levels and the non-lin

A. Pimenov, A. V. Pronin, A. Loidl, A. Kampf

The anisotropic conductivity of a series of tilted Nd_{1.85}Ce_{0.15}CuO_{4-δ} thin films was measured by quasioptical spectroscopy in the frequency range 3cm^{-1}<ν<40cm^{-1}. Two characteristic features have been observed in the low-temperature transmission spectra. The first one at ν= 12cm^{-1} was shown to reflect the c-axis plasma frequency of Nd_{1.85}

G. M. Buendia, E. Machado

The magnetic behavior of a mixed Ising ferrimagnetic system on a square lattice, in which the two interpenetrating square sublattices have spins +- 1/2 and spins +-1,0, in the presence of an oscillating magnetic field has been studied with Monte Carlo techniques. The model includes nearest and next-nearest neighbor interactions, a crystal field and the oscil

S. B. Yuste, A. Santos, M. López de Haro

A method to obtain (approximate) analytical expressions for the radial distribution functions in a multicomponent mixture of additive hard spheres that was recently introduced is used to obtain the direct correlation functions and bridge functions in these systems. This method, which yields results practically equivalent to the Generalized Mean Spherical App

I. Carusotto, Y. Castin, J. Dalibard

We present a numerically tractable method to solve exactly the evolution of a N boson system with binary interactions. The density operator of the system rho is obtained as the stochastic average of particular operators |Psi_1><Psi_2| of the system. The states |Psi_{1,2}> are either Fock states |N:phi_{1,2}> or coherent states |coh:phi_{1,2}> with each parti

E. P. Nakhmedov, M. Kumru, R. Oppermann

A diagrammatic method is applied to study the effects of commensurability in two-dimensional disordered crystalline metals by using the particle-hole symmetry with respect to the nesting vector P_0={\pmπ/a, π/a} for a half-filled electronic band. The density of electronic states (DoS) is shown to have nontrivial quantum corrections due to both nesting and el

O. Benichou, J. Klafter, M. Moreau, G. Oshanin

We study the dynamics of a carrier, which performs a biased motion under the influence of an external field E, in an environment which is modeled by dynamic percolation and created by hard-core particles. The particles move randomly on a simple cubic lattice, constrained by hard-core exclusion, and they spontaneously annihilate and re-appear at some prescrib

D. V. Shantsev, A. V. Bobyl, Y. M. Galperin, T. H. Johansen

Two commonly accepted approaches for simulations of thermally-activated vortex motion in superconductors are compared. These are (i) the so-called flux creep approach based on the expression E=vB relating the electric field E to the velocity v of the thermally-activated flux motion and the local flux density B, and (ii) the approach employing a phenomenologi

Thomas Vojta, Frank Epperlein, Svetlana Kilina, Michael Schreiber

We numerically investigate how electron-electron interactions influence the transport properties of disordered electrons in two dimensions. Our study is based on the quantum Coulomb glass model appropriately generalized to include the spin degrees of freedom. In order to obtain the low-energy properties of this model we employ the Hartree-Fock based diagonal

G. T. Barkema, B. Widom

An earlier one-dimensional lattice model of hydrophobic attraction is extended to two and three dimensions and studied by Monte Carlo simulation. The solvent-mediated contribution to the potential of mean force between hydrophobic solute molecules and the solubility of the solute are determined. As in the earlier model, an inverse relation is observed betwee

P. Argyrakis, S. F. Burlatsky, E. Clement, G. Oshanin

We study analytically kinetics of an elementary bimolecular reaction scheme of the Langmuir-Hinshelwood type taking place on a d-dimensional catalytic substrate. We propose a general approach which takes into account explicitly the influence of spatial correlations on the time evolution of particles mean densities and allows for the analytical analysis. In t

Xi Dai, Tao Xiang, Tai-Kai Ng, Zhao-bin Su

We study the current noise spectra of a tunnel junction of a metal with strong pairing phase fluctuation and a superconductor. It is shown that there is a characteristic peak in the noise spectrum at the intrinsic Josephson frequency $ω_J=2eV$ when $ω_J$ is smaller than the pairing gap but larger than the pairing scattering rate. In the presence of an AC vol

E. Ben-Naim, P. L. Krapivsky

We study scaling properties of stochastic aggregation processes in one dimension. Numerical simulations for both diffusive and ballistic transport show that the mass distribution is characterized by two independent nontrivial exponents corresponding to the survival probability of particles and monomers. The overall behavior agrees qualitatively with the mean

P. L. Krapivsky, E. Ben-Naim

We investigate a class of stochastic aggregation processes involving two types of clusters: active and passive. The mass distribution is obtained analytically for several aggregation rates. When the aggregation rate is constant, we find that the mass distribution of passive clusters decays algebraically. Furthermore, the entire range of acceptable decay expo

Grigorii P. Mikitik, Ernst Helmut Brandt

An exact analytical solution is given for the critical state problem in long thin superconductor strips in a perpendicular magnetic field, when the critical current density j_c(B) depends on the local induction B according to a simple three-parameter model. This model describes both isotropic superconductors with this j_c(B) dependence, but also superconduct

Grigorii P. Mikitik, Ernst Helmut Brandt

A thin flat superconductor of arbitrary shape and with arbitrary in-plane and out-of-plane anisotropy of flux-line pinning is considered, in an external magnetic field normal to its plane. It is shown that the general three-dimensional critical state problem for this superconductor reduces to the two-dimensional problem of an infinitely thin sample of the sa

William Kunkel, Serge Demers, M. J. Irwin

The kinematics of 150 carbon stars observed at moderate dispersion on the periphery of the Small Magellanic Cloud are compared with the motions of neutral hydrogen and early type stars in the Inter-Cloud region. The distribution of radial velocities implies a configuration of these stars as a sheet inclined at 73+/-4 degrees to the plane of the sky. The near

Denise A. Smith, Ronald J. Allen, Ralph C. Bohlin, Natalya Nicholson

Recent studies of nearby spiral galaxies suggest that photodissociation regions (PDRs) are capable of producing much of the observed HI in galaxy disks. In that case, measurements of the HI column density and the far-ultraviolet (FUV) photon flux provide a new probe of the volume density of the local underlying H_2. We develop the method and apply it to the

Elena Pierpaoli, Douglas Scott, Martin White

The current suite of results from Cosmic Microwave Background anisotropy experiments is fulfilling the promise of providing extraordinary levels of discrimination between cosmological models. We calculate a binned anisotropy power spectrum, which we tabulate, along with error bars and bin-to-bin correlations, so that it can be easily used for constraining mo

The MACHO collaboration, C. Alcock, R. A. Allsman, D. R. Alves

The MACHO project is a search for dark matter in the form of massive compact halo objects (MACHOs). The project has photometrically monitored tens of millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge in search of rare gravitational microlensing events caused by these otherwise invisible objects. In 5.7 ye

Georges Meylan

Star clusters - open and globulars - experience dynamical evolution on time scales shorter than their age. Consequently, open and globular clusters provide us with unique dynamical laboratories for learning about two-body relaxation, mass segregation from equipartition of energy, and core collapse. We review briefly, in the framework of star clusters, some e

Francis P. Wilkin

A new solution method is presented for steady-state, momentum-conserving, non-axisymmetric bow shocks and colliding winds in the thin-shell limit. This is a generalization of previous formulations to include a density gradient in the pre-shock ambient medium, as well as anisotropy in the pre-shock wind. For cases where the wind is unaccelerated, the formalis

R. A. Shafer, S. H. Moseley,, P. A. R. Ade, D. J. Benford

SAFIRE is a versatile imaging Fabry-Perot spectrograph covering 145 to 655 microns, with spectral resolving powers ranging over 5-10,000. Selected as a &#34;PI&#34; instrument for the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA), SAFIRE will apply two-dimensional pop-up bolometer arrays to provide background-limited imaging spectrometry.

Zoltan Kollath, J. Robert Buchler

The status of the hydrodynamical modelling of nonlinear multi-mode stellar pulsations is discussed. The hydrodynamical modelling of steady double-mode (DM) pulsations has been a long-standing quest that is finally being concluded. Recent progress has been made thanks to the introduction of turbulent convection in the numerical hydrodynamical codes which prov

L. O&#39;C. Drury, J. T. Mendonca

The Euler equations of ideal gas dynamics posess a remarkable nonlinear involutional symmetry which allows one to factor out an arbitrary uniform expansion or contraction of the system. The nature of this symmetry (called by cosmologists the transformation to supercomoving variables) is discussed and its origin clarified. It is pointed out that this symmetry

Marius J. Fullana, Diego Saez

In some scenarios, the peculiar gravitational potential of linear and mildly nonlinear structures depends on time and, as a result of this dependence, a late integrated Sachs-Wolfe effect appears. Here, an appropriate formalism is used which allows us to improve on the analysis of the spatial scales and locations of the main cosmological inhomogeneities prod

D. K. Aitken, J. S. Greaves, A. Chrysostomou, W. S. Holland

We report the detection of linear polarization from SgrA* at 750, 850, 1350 and 2000 microns which confirms the contribution of synchrotron radiation. From the lack of polarization at longer wavelengths it appears to arise in the millimetre/sub-millimetre excess. There are large position angle changes between the millimetre and sub-millimetre results and the

Kailash C. Sahu

We present the discovery observations of the optical counterpart of the gamma-ray burster GRB990712 taken 4.16 hours after the outburst and discuss its light curve observed in the V, R and I bands during the first ~35 days after the outburst. The observed light curves were fitted with a power-law decay for the optical transient (OT), plus an additional compo

D. V. Bisikalo, A. A. Boyarchuk, O. A. Kuznetsov, V. M. Chechetkin

We present the results of three-dimensional numerical simulations of mass transfer in semi-detached binary with a donor star whose rotation vector precesses around the orbital rotation axis of the binary in the observer&#39;s coordinate frame. The calculations support our previous model of flow without a `hot spot&#39;. Characteristic features of the flow in

K. Benabed, F. Bernardeau, L. Van Waerbeke

We study heterogeneous quantities that efficiently cross-correlate the lensing information encoded in CMB polarization and large-scale structures recovered from weak lensing galaxy surveys. These quantities allow us to take advantage of the special features of weak lensing effect on CMB B-polarization and of the high (40%) cross-correlation between the two d

M. Uemura, T. Kato, K. Matsumoto, K. Takamizawa

We discovered a new deeply eclipsing SU UMa-type dwarf nova, IY UMa, which experienced a superoutburst in 2000 January. Our monitoring revealed two distinct outbursts, which suggest a superoutburst interval of ~800 d, or its half, and an outburst amplitude of 5.4 mag. From time-series photometry during the superoutburst, we determined a superhump and orbital

L. Mantegazza

The phenomenology associated with line profile variations in delta Scuti stars is reviewed. The three main techniques adopted to detect pulsation modes, i.e., the pixel-by-pixel analysis, the analysis of the moment time series and the Fourier Doppler Imaging are presented and discussed. Their application to the observational data has allowed the reliable det

Giovanni Carraro

We report on CCD photometry in the Johnson B,V and I passbands for 146 stars in a 9&#39; \times 9&#39; region around the southern aggregate NGC 6994 (C 2056-128), which appears in the Lynga (1987) catalogue of open star clusters. We argue that this object is not really an open cluster, but simply a random enhancement of four bright stars above the background

Giovanni Carraro, Cesario Lia

By means of N-body/hydrodynamical simulations we model the evolution of a primordial 10^{8} solar masses density peak which ends up in an object closely resembling the present day globular cluster Omega Centauri. We succeed to reproduce the main features of the cluster, namely the structure, kinematics and metallicity distribution. We suggest that Omega Cent

Cheongho Han

Astrometric observations of microlensing events were originally proposed to determine the lens proper motion with which the physical parameters of lenses can be better constrained. In this proceeding, we demonstrate that besides this original usage astrometric microlensing observations can be additionally used in obtaining various important information about

Zoltan Haiman, Marco Spaans, Eliot Quataert

The baryons inside high-redshift halos with virial temperatures above T=10^4 K cool radiatively as they condense inside dark matter potential wells. We show that the release of the gravitational binding energy, over the halo assembly time-scale, results in a significant and detectable Ly alpha flux. At the limiting line flux of approximately 10^-19 erg/s/cm^

Robert L. Kurucz

These descriptive comments are made to encourage detailed three-body, relativistic, quantum collision calculations for the pp reaction. In stars, coulomb barrier tunneling, as in the pp reaction, is not a two-body process. Tunneling is mediated by an energetic electron that interacts with the colliding particles. The presence of such an electron lowers the p

G. V. Kraniotis, S. B. Whitehouse

In this paper a new theory of Dark Matter is proposed. Experimental analysis of several Galaxies show how the non-gravitational contribution to galactic Velocity Rotation Curves can be interpreted as that due to the Cosmological Constant $Λ$. The experimentally determined values for $Λ$ are found to be consistent with those expected from Cosmological Constra