November 1999 arXiv papers — page 25

Jeremy King, Anita Krishnamurthi, Marc H. Pinsonneault

The dispersion in lithium abundance at fixed effective temperature in young cool stars like the Pleiades has proved a difficult challenge for stellar evolution theory. We propose that Li abundances relative to a mean temperature trend, rather than the absolute abundances, should be used to analyze the spread in abundance. We present evidence that the dispers

K. V. Protasov, G. Bonomi, E. Lodi Rizzini, A. Zenoni

The recent experimental data obtained by the OBELIX group on $\bar{p}$D and $\bar{p}^4$He total annihilation cross sections are analyzed. The combined analysis of these data with existing antiprotonic atom data allows, for the first time, the imaginary parts of the S-wave scattering lengths for the two nuclei to be extracted. The obtained values are: $Im a^{

Tamas S. Biro

We obtain an extension of Bjorken's 1+1 dimensional scaling relativistic flow solution to relativistic transverse velocities with cylindrical symmetry in 1+3 dimensions at constant, homogeneous pressure (vanishing sound velocity). This can be the situation during a first order phase transition converting quark matter into hadron matter in relativistic he

P. Mukherjee

Soliton modes in a gauged sigma model with interpolating potential have been investigated. Numerical solutions using a fourth order Runge -- Kutta method are discussed. By tuning the interpolation parameter the transition from symmetrybreaking to the symmetric phase is highlighted.

Sean Fleming, Thomas Mehen, Iain W. Stewart

The 1S0, 3S1, and 3D1 nucleon-nucleon scattering phase shifts are calculated at next-to-next-to-leading order (NNLO) in an effective field theory. Predictions for the 1P1, 3P0, 3P1, 3P2, 1D2, 3D2, and 3D3 phase shifts at this order are also compared with data. The calculations treat pions perturbatively and include the NNLO contributions from order $Q_r^3$ a

Chao-Shang Huang, Wu-Jun Huo, Yue-Liang Wu

If the fourth generation fermions exist, the new quarks could influence the branching ratios of the decays of $B\to X_s γ$ and $B\to X_sl^+l^-$. We obtain two solutions of the fourth generation CKM factor $V^{*}_{t^{'}s}V_{t^{'}b}$ from the decay of $B\to X_s γ$. We use these two solutions to calculate the new contributions of the fourth generation q

Alexander Maloney, Marcus Spradlin, Andrew Strominger

Quantum mechanics on the moduli space of N supersymmetric Reissner-Nordstrom black holes is shown to admit 4 supersymmetries using an unconventional supermultiplet which contains 3N bosons and 4N fermions. A near-horizon limit is found in which the quantum mechanics of widely separated black holes decouples from that of strongly-interacting, near-coincident

D. Korotkin

We collect some classical results related to analysis on the Riemann surfaces. The notes may serve as an introduction to the field: we suppose that the reader is familiar only with the basic facts from topology and complex analysis. the treatment is organized to give a background for further applications to non-linear differential equations.

Wai Bong Yeung

We regard the real and imaginary parts of the Schrodinger wave function as canonical conjugate variables.With this pair of conjugate variables and some other 2n pairs, we construct a quadratic Hamiltonian density. We then show that the Schrodinger Equation follows from the Hamilton's Equation of motion when the Planck frequency is much larger than the ch

Dmitri Volchenkov, Ricardo Lima

The response of inviscid incompressible unbounded fluid subject to a localized external perturbation is studed. The physically relevant hypotheses on the mode coupling mechanisma is justified by renormalization group method. The scaling laws for the scalar and vector velocity potentials are derived. The spectrum of energy of perturbed fluid versus the distan

Dmitri Volchenkov, Ricardo Lima

A flux of ideal fluid coupled to perturbation is investigated by nonperturbative methods of the quantum field theory. Asymptotic behavior of the flux coupled to perturbation turns out to be similiar to that of superfluids.

H. Nakamura, K. Sawada, H. Kambe, T . Saiki

The finite-difference time-domain (FDTD) method is employed to solve the three dimensional Maxwell equation for the situation of near-field microscopy using a sub-wavelength aperture. Experimental result on unexpected high spatial resolution is reproduced by our computer simulation.

Nikolai V. Erkaev, Vladimir S. Semenov, Ferdinand Jamitzky

Reconnection rate is found for the canonical simplest case of steady-state two-dimensional symmetric reconnection in an incompressible plasma by matching of outer Petschek solution and internal diffusion region solution. The reconnection rate obtained naturally incorporates both Sweet-Parker and Petschek regimes, the latter seems to be possible only for the

Dmitri Volchenkov, Ricardo Lima

The statistics of wrinkling flame front is invetigated by the quantum filed theory methods. We dwell on the WKB approximation in the functional integral which is analogous to the Wyld functional integral in turbulence. The main contribution to statistics is due to a coupled field-force configuration. This configuration is related to a kink between metastable

C. Wagner, H. W. Mueller, K. Knorr

We report on surface wave pattern formation in a Faraday experiment operated at a very shallow filling level, where modes with a subharmonic and harmonic time dependence interact. Associated with this distinct temporal behavior are different pattern selection mechanisms, favoring squares or hexagons, respectively. In a series of bifurcations running through

Pu Xu, Jia-Lun Ping, Fan Wang, T. Goldman

The charge symmetry breaking and charge independence breaking N-N ^1S_0 scattering length differences, Delta a_{CSB} and Delta a_{CIB}, are calculated by a resonating group method with a quark cluster model. By adding the QED-QCD interference effect to the quark mass difference and the electromagnetic interaction, the Delta a_{CSB} and Delta a_{CIB} values c

G. G. Adamian, N. V. Antonenko, A. Diaz-Torres, W. Scheid

Mass parameters for collective variables of a dinuclear system and strongly deformed mononucleus are microscopically formulated with the linear response theory making use of the width of single particle states and the fluctuation-dissipation theorem. For the relative motion of the nuclei and for the degree of freedom describing the neck between the nuclei, w

T. M. Shneidman, G. G. Adamian, N. V. Antonenko, S. P. Ivanova

Potential energies, moments of inertia, quadrupole and octupole moments of dinuclear systems are compared with the corresponding quantities of strongly deformed nuclei. As dinuclear system we denote two touching nuclei (clusters). It is found that the hyperdeformed states of nuclei are close to those of nearly symmetric dinuclear systems, whereas the superde

P. Schuck, M. Beyer, G. Roepke, W. Schadow

Residual interactions in many particle systems lead to strong correlations. A multitude of spectacular phenomenae in many particle systems are connected to correlation effects in such systems, e.g. pairing, superconductivity, superfluidity, Bose-Einstein condensation etc. Here we focus on few-body bound states in a many-body surrounding.

Jan Ryckebusch, Wim Van Nespen

Polarization observables for the A(e,e'NN) and A(γ,NN) reactions are a powerful tool to study nucleon-nucleon correlations in the nuclear medium. In this paper, model calculations for the ^{4}He(e,e'pp), ^{16}O(\vec{e},e'\vec{p}p), ^{16}O(\vec{e},e' \vec{p}n) and ^{12}C(\vecγ,\vec{p}N) reactions are presented. The sensitivity of the different

P. Di Francesco

We present a detailed study of the combinatorial interpretation of matrix integrals, including the examples of tessellations of arbitrary genera, and loop models on random surfaces. After reviewing their methods of solution, we apply these to the study of various folding problems arising from physics, including: the meander (or polymer folding) problem ``enu

K. V. Tabunshchyk

We present the Hamilton-Jakobi method for the classical mechanics with constrains in Grassmann algebra. In the frame of this method the solution for the classical system characterized by the SUSY Lagrangian is obtained.

Tevian Dray, Corinne A. Manogue

We discuss the eigenvalue problem for 3x3 octonionic Hermitian matrices which is relevant to the Jordan formulation of quantum mechanics. In contrast to the eigenvalue problems considered in our previous work, all eigenvalues are real and solve the usual characteristic equation. We give an elementary construction of the corresponding eigenmatrices, and we fu

Diego Noja, Andrea Posilicano

We report on some recent work of the authors showing the relations between singular (point) perturbation of the Laplacian and the dynamical system describing a charged point particle interacting with the self-generated radiation field (the Maxwell-Lorentz system) in the dipole approximation. We show that in the limit of a point particle, the dynamics of the

G. Godefroy, N. J. Kalton, G. Lancien

We prove some rather precise renorming theorems for Banach spaces with Szlenk index $ω_0$. We use these theorems to show the invariance of certain quantitative Szlenk-type indices under uniform homeomorphisms.

G. Godefroy, N. J. Kalton, G. Lancien

We show that the class of subspaces of c_0 is stable under Lipschitz isomorphisms. The main corollary is that any Banach space which is Lipschitz isomorphic to c_0 is linearly isomorphic to c_0.

Aidan Schofield

Let αbe a Schur root; let h=hcf_v(α(v)) and let p = 1 - < α/h,α/h >. Then a moduli space of representations of dimension vector αis birational to p h by h matrices up to simultaneous conjugacy. Therefore, if h=1,2,3 or 4, then such a moduli space is a rational variety and if h divides 420 it is a stably rational variety.

I. Gasparis, D. H. Leung

It is shown that the Schreier space X admits a set of continuum cardinality whose elements are mutually incomparable complemented subspaces spanned by subsequences of the natural Schauder basis of X.

Ken Dykema

Certain classes of automorphisms of recued amalgamated free products of C*-algebras are shown to have Brown-Voiculescu topological entropy zero. Also, for automorphisms of exact C*-algebras, the Connes-Narnhofer-Thirring entropy is shown to be bounded above by the Brown-Voiculescu entropy. These facts are applied to generalize Stormer&#39;s result about entr

Ken Dykema, Mikael Rordam

Let (A,phi) be the reduced free product of infinitely many pairs (A_i,phi_i) of C*-algebras with faithful states. Assume that the A_i are not too small, in a specific sense. It is shown that if phi is a trace then K_0(A) is determined entirely by K_0(phi). If, furthermore, the image of K_0(phi) is dense in the reals then A has real rank zero. On the other ha

Marie Choda, Ken Dykema

In the reduced free product of C*-algebras (A,phi)=(A_1,phi_1)*(A_2,phi_2), A is shown to be purely infinite and simple under the hypothesis that A_1 is the crossed product of a C*-algebra by a discrete infinite group, phi_1 is well behaved with respect to this crossed product and A_2 is not one dimensional.

Ken Dykema

Certain reduced free products of C*-algebras, (A,phi)=(A_1,phi_1)*(A_2,ϕ_2), taken with respect to faithful states, at least one of which is not a trace, are shown to be purely infinite and simple. It is assumed that one of the A_i contain a partial isometry in the spectral subspace of phi_i corresponding to a positive number not equal to one. For example, i

Swatee Naik, Theodore Stanford

Two knots in three-space are S-equivalent if they are indistinguishable by Seifert matrices. We show that S-equivalence is generated by the doubled-delta move on knot diagrams. It follows as a corollary that a knot has trivial Alexander polynomial if and only if it can be undone by doubled-delta moves.

Stefan Schroeer

We construct examples of non-projective normal proper algebraic surfaces and discuss the pathological behaviour of their Neron-Severi group. Our surfaces are birational to the product of a projective line and a curve of higher genus.

Michael Kapovich, Bruce Kleiner

We study discrete group actions on coarse Poincare duality spaces, e.g. acyclic simplicial complexes which admit free cocompact group actions by Poincare duality groups. When G is an (n-1) dimensional duality group and X is a coarse Poincare duality space of formal dimension n, then a free simplicial action of G on X determines a collection of ``peripheral&#

Ken Dykema, Dimitri Shlyakhtenko

Let H be a full Hilbert bimodule over a C*-algebra A. We show that the Cuntz-Pimsner C*-algebra associated to H is exact if and only if A is exact. Using this result, we give alternative proofs for exactness of reduced amalgamated free products of exact C*-algebras. In the case that A is a finite dimensional C*-algebra, we also show that the Brown-Voiculescu

Ken Dykema

Some completely positive maps on reduced amalgamated free products of C*-algebras are constructed; these allow a proof that the class of exact unital C*-algebras is closed under taking reduced amalgamated free products. Consequently, the class of exact discrete groups is closed under taking amalgamated free products.

A. Silverberg, Yu. G. Zarhin

In this paper we study the étale cohomology groups associated to abelian varieties. We obtain necessary and sufficient conditions for an abelian variety to have semistable reduction (or purely additive reduction which becomes semistable over a quadratic extension) in terms of the action of the absolute inertia group on the étale cohomology groups with finite

W. A. Perkins

According to conventional theory, the annihilation reaction p-bar p --> pi_0 pi_0 cannot occur from a p-bar p atomic S state. However, this reaction occurs so readily for antiprotons stopping in liquid hydrogen, that it would require 30% P-wave annihilations. Experimental results from other capture and p-bar p annihilation channels show that the fraction of

Jean-Loup Gervais

This is a continuation of hep-th/9811108, hep-th/9903218, hep-th/9910235, on exact integration technics for modified dynamical equations in ten dimensional supersymmetric gauge theory. A Bäcklund transformation is derived for the Yang type (super) equations previously derived (hep-th/9811108) by M. Saveliev and the author, from the ten dimensional super Yang

Auttakit Chattaraputi, Roberto Emparan, Anne Taormina

We construct new configurations of oppositely charged, static black hole pairs (diholes) in four dimensions which are solutions of low energy string/M-theory. The black holes are extremal and have four different charges. We also consider diholes in other theories with an arbitrary number of abelian gauge fields and scalars, where the black holes can be regar

Bin Wang, Elcio Abdalla

It is shown that three-dimensional charged black holes can approach the extreme state at nonzero temperature. Unlike even dimensional cases, the entropy for the extreme three-dimensional charged black hole is uniquely described by the Bekenstein-Hawking formula, regardless of different treatments of preparing the extreme black hole, namely, Hawking&#39;s tre

S. A. Abel, J. L. F. Barbon, I. I. Kogan, E. Rabinovici

Thermodynamical aspects of string theory are reviewed and discussed.

Justin R. David

This thesis aims to make precise the microscopic understanding of Hawking radiation from the D1/D5 black hole. We present an explict construction of all the shortmultiplets of the ${\cal N}=(4,4)$ SCFT on the symmetric product $\tilde{T}^4/S(Q_1Q_5)$. An investigation of the symmerties of this SCFT enables us to make a one-to-one correspondence beween the su

Raphael Bousso

We aim to establish the holographic principle as a universal law, rather than a property only of static systems and special space-times. Our covariant formalism yields an upper bound on entropy which applies to both open and closed surfaces, independently of shape or location. It reduces to the Bekenstein bound whenever the latter is expected to hold, but co

S. Kharchev, D. Lebedev

Integral representation for the eigenfunctions of quantum periodic Toda chain is constructed for N-particle case. The multiple integral is calculated using the Cauchy residue formula. This gives the representation which reproduces the particular results obtained by Gutzwiller for N=2,3 and 4-particle chain. Our method to solve the problem combines the ideas

Michael Haack, Jan Louis

We study the duality between M-theory compactified on Calabi-Yau fourfolds and the heterotic string compactified on Calabi-Yau threefolds times a circle. Our analysis is based on a comparison of the low energy effective actions in three dimensions.

I. Bars, C. Deliduman, D. Minic

We discuss string theory on AdS(3)xS(3)xM(4) with particular emphasis on unitarity and state-operator correspondence. The AdS-CFT correspondence, in the Minkowski signature, is re-examined by taking into account the only allowed unitary representation: the principal series module of the affine current algebra SL(2,R) supplemented with zero modes. Zero modes

Konstantin Goulianos

We discuss the experimental evidence supporting the concept of universality of the rapidity gap probability in soft and hard diffraction, relate the gap probability to hadronic parton densities, and present a phenomenological model of diffraction in which the structure of the Pomeron is derived from the structure of the parent hadron. Predictions for diffrac

L. Lavoura

In tagged cascade decays of the type P^0 (P^0-bar) -> M^0 / M^0-bar X -> f X there are two complex CPT-violating parameters: one in P^0 - P^0-bar mixing, the other one in M^0 - M^0-bar mixing. I analyze those decays and find that, in principle, the former parameter can be extracted from a careful comparison of their time dependences. CPT violation in M^0 - M

P. Checchia

The spectrum of single-photon events detected in the forward and in the barrel region of a TESLA linear collider detector was studied in order to investigate the production of superlight Gravitino pairs associated with a photon.

V. M. Braun

I give a short summary of QCD sum rule results for hadrons involving a heavy quark, with emphasis on recent developments.

S. V. Goloskokov

We calculate the double spin asymmetry of the diffractive $Q \bar Q$ and vector meson leptoproduction at COMPASS energies. We analyze dependences of the asymmetry on the structure of the Pomeron-proton coupling. It is shown that it is difficult to study the spin structure of the Pomeron coupling with the proton from the A_{ll} asymmetry. The A_{lT} asymmetry

Wojciech Broniowski

Vector meson correlators are studied in effective chiral quark models with both local and non-local regulators. A set of sum rules based on dispersion relations is derived, which allows for a comparison of model predictions to data. We show that the two Weinberg sum rules for vector correlators hold in the non-local model.

Hai-Yang Cheng

The $ΔI=1/2$ rule and direct CP violation $ε&#39;/ε$ in kaon decays are studied within the framework of the effective Hamiltonian approach in conjunction with generalized factorization for hadronic matrix elements. We identify two principal sources responsible for the enhancement of A0/A_2: the vertex-type as well as penguin-type corrections to the matrix el

K. Hornbostel

I present results of a numerical calculation of the effects of light quark-antiquark pairs on the linear heavy-quark potential in light-cone quantized two-dimensional QCD. I extract the potential from the Q-Qbar component of the ground-state wavefunction, and observe string breaking at the heavy-light meson pair threshold. I briefly comment on the states res

Colin Morningstar, Mike Peardon

Results for the inter-quark potential and low-lying SU(3) glueball spectrum from simulations using a new improved action are presented. The action, suitable for highly anisotropic lattices, contains a two-plaquette term coupling with a negative coefficient as well as incorporating Symanzik improvement.

Pavlos Vranas

Results from the Columbia lattice group study of the QCD finite temperature phase transition with dynamical domain wall fermions on $16^3 \times 4$ lattices are presented. These results include an investigation of the U(1) axial symmetry breaking above but close to the transition, the use of zero temperature calculations that set the scale at the transition

TARO Collaboration, Ph. de Forcrand, M. Garcia Perez, T. Hashimoto

We present results for mesonic propagators in temporal and spatial directions at T below and above the deconfining transition in quenched QCD. Anisotropic lattices are used to get enough information in the temporal direction. We use the Wilson fermion action for light quarks and Fermilab action for heavy quarks.

Alan J. Weinstein

We review world-average measurements of the tau lepton electroweak couplings, in both decay (including Michel parameters) and in production ($Z^0\to τ^+τ^-$ and $W^-\toτ^-\nubar_τ$). We review the searches for anomalous weak and EM dipole couplings. Finally, we present the status of several other tau lepton studies: searches for lepton flavor violating decay

B. Majorovits, H. V. Klapdor-Kleingrothaus

The Heidelberg-Moscow Experiment is presently the most sensitive experiment looking for neutrinoless double-beta decay. Recently the already very low background has been lowered by means of a Digital Pulseshape Analysis using a one parameter cut to distinguish between pointlike events and multiple scattered events. To use all the information contained in a r

Ramon Lopez-Aleman

This paper reviews the basic features of the theory of curvature perturbations in Kerr spacetime, which is customarily written in terms of gauge invariant components of the Weyl tensor which satisfy a perturbation equation known as the Teukolsky equation. I will describe how to evolve generic perturbations about the Kerr metric and the separable form of the

A. Mikovic, N. Manojlovic

We find two-dimensional free-field variables for D-dimensional general relativity on spacetimes with D-2 commuting spacelike Killing vector fields and non-compact spatial sections for D>4. We show that there is a canonical transformation which maps the corresponding two-dimensional dilaton gravity theory into a two-dimensional diffeomorphism invariant theory

D. Korotkin, V. Matveev

We review recent developments in the method of algebro-geometric integration of integrable systems related to deformations of algebraic curves. In particular, we discuss the theta-functional solutions of Schlesinger system, Ernst equation and self-dual SU(2)-invariant Einstein equations.

Luis J. Garay

In this work, I review some aspects concerning the evolution of quantum low-energy fields in a foamlike spacetime, with involved topology at the Planck scale but with a smooth metric structure at large length scales, as follows. Quantum gravitational fluctuations may induce a minimum length thus introducing an additional source of uncertainty in physics. The

L. S. Finn, G. Gonzalez, J. Hough, M. F. Huq

An overview of some tools and techniques being developed for data conditioning (regression of instrumental and environmental artifacts from the data channel), detector design evaluation (modeling the science ``reach&#39;&#39; of alternative detector designs and configurations), noise simulations for mock data challenges and analysis system validation, and an

C. Masciovecchio, V. Mazzacurati, G. Monaco, G. Ruocco

New temperature dependent inelastic x-ray (IXS) and Raman (RS) scattering data are compared to each other and with existing inelastic neutron scattering data in vitreous silica (v-SiO_2), in the 300 - 1775 K region. The IXS data show collective propagating excitations up to Q=3.5 nm^-1. The temperature behaviour of the excitations at Q=1.6 nm^-1 matches that

T. Scopigno, U. Balucani, A. Cunsolo, C. Masciovecchio

The dynamic structure factor, S(Q,E), of liquid lithium (T=475 K) has been determined by inelastic x-ray scattering (IXS) in the momentum transfer region (Q = 1.4-110 nm-1). These data allow to observe how, in a simple liquid, a phonon-like collective mode evolves towards the single particle dynamics. As a function of Q, one finds: i) at low Q&#39;s, a sound

T. A. Shutenko, I. L. Aleiner, B. L. Altshuler

We consider the adiabatic charge transport through zero-dimensional mesoscopic sample (quantum dot) caused by two periodically changing external perturbations. Both the magnitude and the sign of the transmitted charge are extremely sensitive to the configuration of the dot and to the magnetic field. We find the correlation function characterizing the random

J. Reidl, A. Csordás, R. Graham, P. Szépfalusy

We present predictions for the temperature dependent shifts and damping rates. They are obtained by applying the dielectric formalism to a simple model of a trapped Bose gas. Within the framework of the model we use lowest order perturbation theory to determine the first order correction to the results of Hartree-Fock-Bogoliubov-Popov theory for the complex

M. J. Holland, B. DeMarco, D. S. Jin

We derive a quantum theory of evaporative cooling for a degenerate Fermi gas with two constituents and show that the optimum cooling trajectory is influenced significantly by the quantum statistics of the particles. The cooling efficiency is reduced at low temperatures due to Pauli blocking of available final states in each binary collision event. We compare

J. M. Pitarke, I. Campillo

A survey is presented of current investigations of the impact of band structure effects on various aspects of the interaction of charged particles with real solids. The role that interband transitions play in the decay mechanism of bulk plasmons is addressed, and results for plasmon linewidths in Al and Si are discussed. {\it Ab initio} calculations of the e

J. -B. Maillet, V. Lachet, P. V. Coveney

We report on an investigation of the structural and dynamical properties of n-nonyltrimethylammonium chloride (C9TAC) and erucyl bis [2-hydroxyethyl] methylammonium chloride (EMAC) micelles in aqueous solution. A fully atomistic description was used, and the time evolution was computed using molecular dynamics.

G. Ruocco, F. Sette, R. Di Leonardo, D. Fioretto

The sound attenuation in the THz region is studied down to T=16 K in glassy glycerol by inelastic x-ray scattering. At striking variance with the decrease found below 100 K in the GHz data, the attenuation in the THz range does not show any T dependence. This result i) indicates the presence of two different attenuation mechanisms, active respectively in the

G. Brunthaler, A. Prinz, G. Bauer, V. M. Pudalov

The negative magnetoresistance due to weak localization is investigated in the two-dimensional metallic state of Si-MOS structures for high conductance values between 35 and 120 e^2/h. The extracted phase coherence time is equal to the momentum relaxation time at 10 K but nearly 100 times longer at the lowest temperature. Nevertheless, only weak logarithmic

Dmitri Volchenkov, Ricardo Lima

We have calculated the asymptotics of Green&#39;s function of the differential equation of nonlinear diffusion in the microscopic range with strong porosity fluctuations in the problem of flow through irregular packed beds for arbitrary space dimension and arbitrary covariance of porosity fluctuations.

G. A. Ovsyannikov, I. V. Borisenko, K. Y. Constantinian

The results of dc, microwave and magnetic measurements of YBCO bicrystal junctions on r-cut sapphire are presented. The junctions with high resistance 10-20 W and IcRN= 1-2 mV and tolerance of RNS around 30% on chip allow to create microwave circuits with low integration (up to 10 junctions on chip). The microwave dynamics of the junction with superconductin

Simona Cocco, Remi Monasson

The instantaneous normal modes corresponding to base pair vibrations (radial modes) and twist angle fluctuations (angular modes) of a DNA molecule model at ambient temperature are theoretically investigated. Due to thermal disorder, normal modes are not plane waves with a single wave number q but have a finite and frequency dependent damping width. The densi

Alexei A. Koulakov

The influence of the synaptic channel properties on the stability of delayed activity maintained by recurrent neural network is studied. The duration of excitatory post-synaptic current (EPSC) is shown to be essential for the global stability of the delayed response. NMDA receptor channel is a much more reliable mediator of the reverberating activity than AM

Erik Luijten

We calculate universal finite-size scaling functions for systems with an n-component order parameter and algebraically decaying interactions. Just as previously has been found for short-range interactions, this leads to a singular epsilon-expansion, where epsilon is the distance to the upper critical dimension. Subsequently, we check the results by numerical

Shay Caspi, Eshel Ben-Jacob

We suggest that Davidov&#39;s solitons, propagating through the backbone of a protein, can mediate conformational transition and folding of a protein to its native state. A simple toy model is presented in which a Non Linear Schrodinger (NLS) field interacts with another field phi, corresponding to the conformation angles of the protein. The interaction prov

Eugene B. Kolomeisky, Joseph P. Straley

The macroscopic zero-temperature behavior of weakly- incommensurate systems in one dimension is described in terms of solitons. The soliton density n obeys equations displaying several types of singular interface-like solutions: (i) equilibrium or moving boundary between the n = 0 and finite n regions, and (ii) stationary or moving annihilation front separat

F. Hebert, G. G. Batrouni, H. Mabilat

We derive the exact dual to the Bosonic Hubbard model. The dual variables take the form of conserved current loops (local and global). Previously this has been done only for the very soft core model at very high density. No such approximations are made here. In particular, the dual of the hard core model is shown to have a very simple form which is then used

Tamara A. Leskova, Ingve Simonsen, Alexei A. Maradudin

We study the statistical properties of the scattering matrix S(q|k) for the problem of the scattering of light from a randomly rough one-dimensional surface, defined by the equation $x_3 = \zx$, where the surface profile function $\zx$ constitutes a zero-mean, stationary, Gaussian random process, through the effects of $S(q|k)$ on the angular intensity corre

Haim Diamant, David Andelman

The onset of self-assembly in a dilute aqueous solution containing a flexible polymer and surfactant is theoretically studied. Focusing on the effect of the surfactant on polymer conformation and using a conjecture of partial collapse of the polymer at the onset of self-assembly, we obtain results which agree with known experimental observations: (i) polymer

D. S. Saraga, T. S. Monteiro

We derive semiclassical expressions for spectra, weighted by matrix elements of a Gaussian observable, relevant to a range of molecular and mesoscopic systems. We apply the formalism to the particular example of the resonant tunneling diode (RTD) in tilted fields. The RTD is a new experimental realization of a mesoscopic system exhibiting a transition to cha

P. N. Walker, T. S. Monteiro

We develop a semiclassical theory for the spectral rigidity of non-hydrogenic Rydberg atoms in electric fields and evaluate the significant deviations from the well-known Poissonian behaviour in the hydrogenic case. The resulting formula is shown to be in excellent agreement with the exact quantal result. We also investigate diamagnetic atoms; we find that,

Martin Wolf, Jürgen Schmiegel, Martin Greiner

A multifractal phase transition is associated to a nonanalyticity in the generalised dimensions. We show that its occurrence is an artifact of the asymptotic scaling behaviour of integral moments and that it is not observed in an analysis based on differential n-point correlation densities.

I. M. Sokolov

We consider two-particle dispersion in a velocity field, where the relative two-point velocity scales according to $v^{2}(r)\propto r^α$ and the corresponding correlation time scales as $τ(r)\propto r^β$, and fix $α=2/3$, as typical for turbulent flows. We show that two generic types of dispersion behavior arize: For $α/2+β< 1$ the correlations in relative v

A. Sills, M. Pinsonneault

The rotation of horizontal branch stars places important constraints on angular momentum evolution in evolved stars and therefore rotational mixing on the giant branch. Prompted by new observations of rotation rates of horizontal branch stars, we calculate simple models for the angular momentum evolution of a globular cluster giant star from the base of the

A. Sills, C. Bailyn, P. Edmonds, R. Gilliland

We investigate the effects of changes in the blue straggler formation rate in globular clusters on the blue straggler distribution in the color-magnitude diagram. We find that the blue straggler distribution is highly sensitive to the past formation rate. Comparing our models to new UBV observations of a region close to the core of 47 Tucanae suggests that t

L. D. Matthews, W. van Driel, J. S. Gallagher

`Superthins&#39; are a subset of edge-on spiral galaxies exhibiting disks with large axial ratios (a/b>10), extraordinarily small stellar scale heights, and no bulge component. These are thus examples of dynamically cold, pure disk galaxies. We have recently obtained multiwavelength (HI, optical, NIR) observations for a large sample of superthin spirals. Our

Eric D. Miller, Joel N. Bregman, Patricia M. Knezek

Cool gas should be present in galaxy clusters due to stripping of galactic gas, infall onto the cluster, and from cooling flows. We searched for this gas through resonance absorption line observations from low-ionization metal line gas toward six background quasars. Both cooling flow and non-cooling flow clusters were observed, with lines of sight from the i

G. S. Da Costa, T. E. Armandroff, Nelson Caldwell, Patrick Seitzer

The HST WFPC2 camera has been used to image Andromeda II, a dwarf spheroidal (dSph) companion to M31. The resulting color-magnitude diagrams reveal the morphology of the horizontal branch (HB) in this dwarf galaxy. We find that like Andromeda I, and like most of the Galactic dSph companions, the HB morphology of And II is predominantly red. Unlike And I, how

S. Lipari, R. Diaz, Y. Taniguchi, R. Terlevich

We find in a detailed morphological study (at 15 pc resolution) that the extended massive star formation process, shows: (i) extended triple asymmetrical spiral arms structure (r = 5 kpc); and (ii) the spiral arms emanate from three different nuclei. The main optical nucleus shows a small spiral-disk (r = 500 pc) which is a continuation of the external one a

Vladimir V. Vassiliev

Recent observations of the TeV gamma-ray spectra of the two closest active galactic nuclei (AGNs), Markarian 501 (Mrk 501) and Markarian 421 (Mrk 421), by the Whipple and HEGRA collaborations have stimulated efforts to estimate or limit the spectral energy density (SED) of extragalactic background light (EBL) which causes attenuation of TeV photons via pair-

N. Christlieb, D. Reimers, L. Wisotzki, J. Reetz

We report on a search for extremely metal-poor ([Fe/H]<-3.0) turnoff stars in the Hamburg/ESO objective prism survey (HES). Metal-poor stars are selected by automatic spectral classification. Extensive simulations show that the selection efficiency for turnoff stars of [Fe/H]<-3.0 is >25% at B<16.5. Since the HES is more than 1 mag deeper than the HK survey

J. R. Mattox

Because of the scheduled GLAST mission by NASA, there is strong scientific justification for preparation for very extensive blazar monitoring in the optical bands to exploit the opportunity to learn about blazars through the correlation of variability of the gamma-ray flux with flux at lower frequencies. Current optical facilities do not provide the required

Sitki Cagdas Inam, Altan Baykal

Using archival BATSE (Burst and Transient Source Experiment) 20-60 keV band X-ray flux and pulse frequency time series, we look for correlations between torque, luminosity and specific angular momentum for three high mass X-ray binary pulsars Vela X-1, GX 301-2 and OAO 1657-415. Our results show that there is no correlation between pulse frequency derivative

Andreas Eckart, Thomas Ott, Reinhard Genzel

We report preliminary results based on new near-infrared observations of the central stellar cluster of our Galaxy conducted with the infrared spectrometer ISAAC at the ESO VLT UT1 and the MPE speckle camera SHARP at the ESO NTT. We obtained lambda / dlambda >= 3000 K-band spectroscopy of the 2.058 um He I, 2.165 um Br gamma emission lines, and 2.29 um CO ba