February 2001 arXiv papers — page 19

Saharon Shelah

For cardinals lambda, kappa, theta we consider the class of graphs of cardinality lambda which has no subgraph which is (kappa, theta)-complete bipartite graph. The question is whether in such a class there is a universal one under (weak) embedding. We solve this problem completely under GCH. Under various assumptions mostly related to cardinal arithmetic we

Marc Bocquet, Fabian H. L. Essler, Alexei M. Tsvelik, Alexander O. Gogolin

We study the dynamical response of frustrated, quasi-one-dimensional spin-1/2 Heisenberg antiferromagnets at finite temperatures. We allow for the presence of a Dzyaloshinskii-Moriya interaction. We concentrate on a model of weakly coupled planes of anisotropic triangular lattices. Combining exact results for the dynamical response of one dimensional Heisenb

F. M. Cucchietti, H. M. Pastawski, D. A. Wisniacki

Classical chaotic dynamics is characterized by the exponential sensitivity to initial conditions. Quantum mechanics, however, does not show this feature. We consider instead the sensitivity of quantum evolution to perturbations in the Hamiltonian. This is observed as an atenuation of the Loschmidt Echo, $M(t)$, i.e. the amount of the original state (wave pac

D. B. Gutman, Yuval Gefen

We study current correlation functions in a diffusive junction out of equilibrium. We calculate corrections to the electric current and to the zero frequency shot noise due to electron-electron interactions. Contrary to the equilibrium situation (where the corrections to the current and to the current noise are related through the fluctuation-dissipation the

Roger M. Hutchings, F. Santoro, P. A. Thomas, H. M. P. Couchman

We calculate the cooling times at constant density for halos with virial temperatures from 100 K to 10^5 K that originate from a 3-sigma fluctuation of a CDM power spectrum in three different cosmologies. Our intention is to determine the first objects that can cool to low temperatures, but not to follow their dynamical evolution. We identify two generations

Jian Dai, Xing-Chang Song

Based on the observation that the moduli of a link variable on a cyclic group modify Connes' distance on this group, we construct several action functionals for this link variable within the framework of noncommutative geometry. After solving the equations of motion, we find that one type of action gives nontrivial vacuum solution for gravity on this cyc

Yi-Ting Chiang, Ching-Chi Lin, Hsueh-I Lu

We introduce and study the {\em orderly spanning trees} of plane graphs. This algorithmic tool generalizes {\em canonical orderings}, which exist only for triconnected plane graphs. Although not every plane graph admits an orderly spanning tree, we provide an algorithm to compute an {\em orderly pair} for any connected planar graph $G$, consisting of a plane

Cecilia Albertsson, Bjorn Brinne, Ulf Lindstrom, Rikard von Unge

We show that the Higgs branch of a four-dimensional Yang-Mills theory, with gauge and matter content summarised by an E_8 quiver diagram, is identical to the generalised Coulomb branch of a four-dimensional superconformal strongly coupled gauge theory with E_8 global symmetry. This is the final step in showing that there is a Higgs-Coulomb identity of this k

Robert S. Priddey, Richard G. McMahon

We combine submm photometric data of z>4 quasars, to obtain a mean far-infrared (FIR) (rest-frame) spectral energy distribution (SED) of thermal emission from dust, parameterised by a single temperature (T) and power-law emissivity index (beta). Best-fit values are T=41+/-5K, beta=1.95+/-0.3. The redshift spread of this set of quasars is exploited to allow u

Kai Chen, Bo-yu Hou

The Lax pair of the Ruijsenaars-Schneider model with interaction potential of trigonometric type based on Dn Lie algebra is presented. We give a general form for the Lax pair and prove partial results for small n. Liouville integrability of the corresponding system follows a series of involutive Hamiltonians generated by the characteristic polynomial of the

G. Mangano, G. Miele, S. Pastor, M. Peloso

We discuss the possibility that a perturbative reheating stage after inflation produces a scalar particle gas in a Bose condensate state, emphasizing the possible cosmological role of this phenomenon for symmetry restoration.

A. V. Kolesnikov, R. Lipperheide, U. Wille

Localized interface states in abrupt semiconductor heterojunctions are studied within a tight-binding model. The intention is to provide a microscopic foundation for the results of similar studies which were based upon the two-band model within the envelope function approximation. In a two-dimensional description, the tight-binding Hamiltonian is constructed

Juan Camacho, Roger Guimera, Luis A. N. Amaral

We investigate numerically and analytically a recently proposed model for food webs [Nature {\bf 404}, 180 (2000)] in the limit of large web sizes and sparse interaction matrices. We obtain analytical expressions for several quantities with ecological interest, in particular the probability distributions for the number of prey and the number of predators. We

Omar Mustafa

The shifted 1/N expansion technique, used by El-Said (Phys. Rev. B 61, 13026 (2000)), to study the relative Hamiltonian of two interacting electrons confined in a quantum dot, is investigated. El-Said's results from SLNT are revised and results from an alternative method are also reported. The distinctive role of the central spike term, $(m^2-1/4)/q^2$,

Ivone F. M. Albuquerque, George F. Smoot

Neutrino telescopes with large detection volumes can demonstrate that the current indications of neutrino oscillation are correct or if a better description can be achieved with non-standard alternatives. Observations of contained muons produced by atmospheric neutrinos can better constrain the allowed region for oscillations or determine the relevant parame

Tetsuya Shiromizu, Daisuke Ida

We study the asymptotic behavior of the bulk spacetimes with the negative cosmological constant in the context of the brane-world scenario. We show that, in Euclidean bulk, or in Lorentzian static bulk, some sequences of hypersurfaces with the positive Ricci scalar evolve to the warped geometries like the anti-de Sitter spacetime. Based on the AdS/CFT corres

Dongsheng Du, Deshan Yang, Guohuai Zhu

Since b quark mass is not asymptotically large, chirally enhanced corrections which arise from twist-3 wave functions may be important in B decays. We thus evaluate the hadronic matrix elements with the final light pseudoscalar mesons described by leading twist and twist-3 distribution amplitudes. We find that chirally enhanced corrections can be included co

Shin'ichi Nojiri, Sergei D. Odintsov

The quantum-induced dilatonic brane world (New Brane World) is created by brane CFT quantum effects (giving effective brane tension) in accordance with AdS/CFT set-up which also defines surface term. Considering the bosonic sector of 5d gauged supergravity with single scalar and taking the boundary action as predicted by supersymmetry, the possibility to sup

D. Montanino

Motivated by recent experimental data, we study solar neutrino oscillations in the range 10^-10 < delta m^2/E < 10^-7 eV^2/MeV. In this range vacuum oscillations become increasingly affected by (solar and terrestrial) matter effects for increasing delta m^2, smoothly reaching the MSW regime. A numerical study of matter effects in such &#34;quasi-vacuum&#34;

Pranaw Rungta, V. Buzek, Carlton M. Caves, M. Hillery

Wootters [Phys. Rev. Lett. 80, 2245 (1998)] has given an explicit formula for the entanglement of formation of two qubits in terms of what he calls the concurrence of the joint density operator. Wootters&#39;s concurrence is defined with the help of the superoperator that flips the spin of a qubit. We generalize the spin-flip superoperator to a &#34;universa

C. Tannous, J. Langlois

Gao applied LeRoy and Bernstein semi-classical analysis for the energy levels in a potential of the form -C/r^n to sequences of scaled energy differences progressing towards low lying states and found a better agreement with the semi-classical prediction. We checked that for the energy levels obtained by Stwalley et al. with the same potential, the agreement

Arun K. Pati, Marek Zukowski

We propose a method called `coherence swapping&#39; which enables us to create superposition of a particle in two distinct paths, which is fed with initially incoherent, independent radiations. This phenomenon is also present for the charged particles, and can be used to swap the effect of flux line due to Aharonov-Bohm effect. We propose an optical version

R. P. Martínez-y-Romero, H. N. Núñez-Yépez, A. L. Salas-Brito

General recurrence relations for arbitrary non-diagonal, radial hydrogenic matrix elements are derived in Dirac relativistic quantum mechanics. Our approach is based on a generalization of the second hypervirial method previously employed in the non-relativistic Schrödinger case. A relativistic version of the Pasternack-Sternheimer relation is thence obtaine

B. Afsari, N. Sadeghi-Meybodi, S. Rouhani

The aim of this paper is to show that Digital Signal Processors (DSPs) can be used to efficiently implement complex algorithms. As an example we have chosen the problem of enumerating closed two-dimensional random paths. An Evaluation Module Board (EVM) for TMS320C6201 fixed-point processor is used. The algorithm is implemented in hand-written parallel assem

K. Efstathiou, G. Contopoulos

We study the forms of the orbits in a symmetric configuration of a realistic model of the H2O molecule with particular emphasis on the periodic orbits. We use an appropriate Poincaré surface of section (PSS) and study the distribution of the orbits on this PSS for various energies. We find both ordered and chaotic orbits. The proportion of ordered orbits is

Jun-nosuke Teramae, Yoshiki Kuramoto

In assemblies of globally coupled dynamical units, weak noise perturbing independently the individual units can cause anomalous dispersion in the synchronized cloud of the units in the phase space. When the noise-free dynamics of the synchronized assembly is nonperiodic, various moments of the linear dimension of the cloud as a function of the noise strength

F. Ginelli, R. Livi, A. Politi

Strong nonlinear effects combined with diffusive coupling may give rise to unpredictable evolution in spatially extended deterministic dynamical systems even in the presence of a fully negative spectrum of Lyapunov exponents. This regime, denoted as ``stable chaos&#39;&#39;, has been so far mainly characterized by numerical studies. In this manuscript we inv

E. G. Kalnins, J. M. Kress, G. S. Pogosyan, W. Miller

We classify the Hamiltonians $H=p_x^2+p_y^2+V(x,y)$ of all classical superintegrable systems in two dimensional complex Euclidean space with second-order constants of the motion. We similarly classify the superintegrable Hamiltonians $H=J_1^2+J_2^2+J_3^2+V(x,y,z)$ on the complex 2-sphere where $x^2+y^2+z^2=1$. This is achieved in all generality using propert

Edwin Langmann

We use loop group techniques to construct a quantum field theory model of anyons on a circle and at finite temperature. We find an anyon Hamiltonian providing a second quantization of the elliptic Calogero-Sutherland model. This allows us to prove a remarkable identity which is a starting point for an algorithm to construct eigenfunctions and eigenvalues of

Markus Kunze, Herbert Spohn

We study the dynamics of N charges interacting with the Maxwell field. If their initial velocities are small compared to the velocity of light, c, then in lowest order their motion is governed by the static Coulomb Lagrangian. We investigate higher order corrections with an explicit control on the error terms. The Darwin correction, order (v/c)^2, has been p

Hong Qian

Using a one-dimensional macromolecule in aqueous solution as an illustration, we demonstrate that the relative entropy from information theory, $\sum_k p_k\ln(p_k/p_k^*)$, has a natural role in the energetics of equilibrium and nonequilibrium conformational fluctuations of the single molecule. It is identified as the free energy difference associated with a

Steve Clark, Fritz Gesztesy

We explicitly determine the high-energy asymptotics for Weyl-Titchmarsh matrices associated with general matrix-valued Schrödinger operators on a half-line.

Anand Dessai

Let $M$ be a manifold homotopy equivalent to the complex projective space $\C P^m$. Petrie conjectured that $M$ has standard total Pontrjagin class if $M$ admits a non-trivial action by $S^1$. We prove the conjecture for $m<12$ under the assumption that the action extends to a nice $Pin(2)$-action with fixed point. The proof involves equivariant index theory

Wilfrid Hodges, Saharon Shelah

In two papers we noted that in common practice many algebraic constructions are defined only `up to isomorphism&#39; rather than explicitly. We mentioned some questions raised by this fact, and we gave some partial answers. The present paper provides much fuller answers, though some questions remain open. Our main result says that there is a transitive model

Andreas Blass, Yuri Gurevich, Saharon Shelah

This paper is motivated by the question whether there exists a logic capturing polynomial time computation over unordered structures. We consider several algorithmic problems near the border of the known, logically defined complexity classes contained in polynomial time. We show that fixpoint logic plus counting is stronger than might be expected, in that it

Oren Kolman, Saharon Shelah

We prove in ZFC that the Baer-Specker group Z^omega has 2^{aleph_1} non-free pure subgroups of cardinality aleph_1 which are almost disjoint: there is no non-free subgroup embeddable in any pair.

Saharon Shelah

This paper is based on the talk given by the author after he received the International Bolyai Prize in Mathematics (on November 4, 2000 in Budapest, Hungary).

M. J. Fryers

This paper explores the birational geometry of a general Horrocks-Mumford quintic threefold, describing the set of all minimal models up to marked isomorphism, the movable fan (the way in which the nef cones of all these models are arranged to form the movable cone), and the birational automorphism group. There are infinitely many models up to marked isomorp

A. V. Ershov

The aim of section 1 is to define the homotopic functor to category of Abelian groups, connected with the special classes of bundles with fiber matrix algebra or projective space. The aim of section 2 is to define some generalization of the notion of formal group. More precisely, we consider the analog of formal groups with coefficients belonging to a Hopf a

Jean-Louis Loday

There is a notion of non-commutative Lie algebra called &#34;Leibniz algebra&#34;, which is characterized by the condition: left bracketing is a derivation. The purpose of this article is to introduce and study a new notion of algebra, called &#34;associative dialgebra&#34;, which is, to the Leibniz algebras, what associative algebras are to Lie algebras. An

Michel Brion, Emmanuel Peyre

We factor the virtual Poincare polynomial of every homogeneous space G/H, where G is a complex connected linear algebraic group and H is an algebraic subgroup, as $t^{2u} (t^2-1)^r Q_{G/H}(t^2)$ for a polynomial $Q_{G/H}$ with non-negative integer coefficients. Moreover, we show that $Q_{G/H}(t^2)$ divides the virtual Poincaré polynomial of every regular emb

Jean-Yves Thibon

We give a generating function for the number of unimodal permutations with a given cycle structure.

P. E. Chaput

R. Hartshorne conjectured and F. Zak proved that any n-dimensional smooth non-degenerate complex algebraic variety X in a m-dimensional projective space P satisfies Sec(X)=P if m<3n/2+2. In this article, I deal with the limiting case of this theorem, namely the Severi varieties, defined by the conditions m=3n/2+2 and Sec(X) different from P. I want to give a

Michael T. Anderson

This paper relates the boundary term in the Chern-Gauss-Bonnet formula on 4-manifolds M with the renormalized volume V, as defined in the AdS/CFT correspondence, for asymptotically hyperbolic Einstein metrics on M. In addition, we compute and discuss the differential or variation dV of V, or equivalently the variation of the L^2 norm of the Weyl curvature, o

Fritz Gesztesy, Alexander Kiselev, Konstantin A. Makarov

Let $g(z,x)$ denote the diagonal Green&#39;s matrix of a self-adjoint $m\times m$ matrix-valued Schrödinger operator $H= -\f{d^2}{dx^2}I_m +Q(x)$ in $L^2 (\bbR)^{m}$, $m\in\bbN$. One of the principal results proven in this paper states that for a fixed $x_0\in\bbR$ and all $z\in\bbC_+$, $g(z,x_0)$ and $g^\prime (z,x_0)$ uniquely determine the matrix-valued $

Frank Ferrari

We discuss in details a simple, purely bosonic, quantum field theory belonging to larger class of models with the following properties: a) They are asymptotically free, with a dynamically generated mass scale. b) They have a space of parameters which gets quantum corrections drastically modifying the classical singularity structure. The quantum theory can ha

Antonio Filippi

The multiplicative anomaly, recently introduced in QFT, plays a fundamental role in solving some mathematical inconsistencies of the widely used zeta-function regularization method. Its physical relevance is still an open question and is here analyzed in the light of a non-perturbative method. Even in this approach the ``different physics&#39;&#39; seems to

F. Finkel, D. Gomez-Ullate, A. Gonzalez-Lopez, M. A. Rodriguez

A new family of A_N-type Dunkl operators preserving a polynomial subspace of finite dimension is constructed. Using a general quadratic combination of these operators and the usual Dunkl operators, several new families of exactly and quasi-exactly solvable quantum spin Calogero-Sutherland models are obtained. These include, in particular, three families of q

Jose I. Latorre, Tim R. Morris

The path integral formulation of Quantum Field Theory implies an infinite set of local, Schwinger-Dyson-like relations. Exact renormalization group equations can be cast as a particular instance of these relations. Furthermore, exact scheme independence is turned into a vector field transformation of the kernel of the exact renormalization group equation und

P. Maraner

It is shown that the local coupling of a higher dimensional graviton to a closed degenerate two-form produces dimensional reduction by spontaneous breakdown of extra-dimensional translational symmetry. Four dimensional Poincaré invariance emerges as residual symmetry. As a specific example, a six dimensional geometry coupled to a closed rank 2 two-form yield

B. de Carlos, M. B. Hindmarsh, N. McNair, J. M. Moreno

In this talk we construct BPS-saturated domain walls in supersymmetric QCD, for any values of the masses of the chiral matter superfields. We compare our results to those already obtained in the literature and we also discuss their range of applicability, as well as future directions that would be desirable to explore in order to achieve a complete understan

Zachary Guralnik

Relations between the global structure of the gauge group in elliptic F-theory compactifications, fractional null string junctions, and the Mordell-Weil lattice of rational sections are discussed. We extend results in the literature, which pertain primarily to rational elliptic surfaces and obtain pi^1(G) where G is the semi-simple part of the gauge group. W

Mauricio Ayala, Richard Haase

Starting from SO(n,m) groups, we are in search of groups that: (1.) in a simple way, include N supersymmetric generators(see \cite{Nahm}) (2.) contain as subgroup: the de Sitter group SO(4,1) or the Anti-de Sitter group SO(3,2) (3.) permit nontrivial gauge symmetry groups. The smallest groups satisfyng above conditions are the OSp(N|4) groups, which contain

Raju Venugopalan

We discuss the physics case for an electron--nucleus collider at RHIC.

A. Afanasev, I. Akushevich, N. Merenkov

The explicit formulae for radiative correction (RC) calculation for elastic $ep$-scattering is presented. Two typical measurements of polarization observables such as beam-target asymmetry or recoil proton polarization, are considered. Possibilities to take into account realistic experimental acceptances are discussed. The Fortran code MASCARAD for providing

Paul Langacker

A brief review is given of precision electroweak physics, and its implications for establishing the standard model and constraining the possibilities for new physics at the TeV scale and beyond.

Jens Erler, Sven Heinemeyer

The high-energy lepton collider TESLA can be operated in the GigaZ mode on the Z resonance, producing a billion Z bosons per year. This will allow the measurement of the effective electroweak mixing angle to an accuracy much better than one part in 10,000. Similarly, the W boson mass is expected to be measurable with an error of 6 MeV near threshold. We disc

T. M. aliev, A. Ozpineci, M. Savci

Using the general, model independent form of effective Hamiltonian, the decay spectrum of B^0 -> pi^+ pi^- l^+ l^- decay is studied. The sensitivity of experimentally measurable asymmetries to the new Wilson coefficients and time is studied. It is observed that different asymmetries are sensitive to the new Wilson coefficients and they can serve as an effici

S. Heinemeyer, W. Hollik, J. Rosiek, G. Weiglein

We calculate the cross sections for the neutral Higgs-boson production at e+e- colliders in the Minimal Supersymmetric Standard Model (MSSM) using the Feynman-diagrammatic approach and the on-shell renormalization scheme. We incorporate the Higgs-boson propagator corrections, evaluated up to two-loop order, into the prediction of the cross sections for the H

Joaquim I. Silva-Marcos

The exact democratic structure for the quark mass matrix, resulting from the action of the family symmetry group $A_{3L}\times A_{3R}$, is broken by the vaccum expectation values of heavy singlet fields appearing in non renormalizable dimension 6 operators. Within this specific context of breaking of the family symmetry we formulate a very simple ansatz whic

Andreas Birkedal-Hansen, Brent D. Nelson

We investigate the dark matter prospects of supersymmetric models with nonuniversal gaugino masses. We find that for very particular values of the ratio of soft supersymmetry-breaking gaugino masses, M2/M1, an enhanced coannihilation efficiency between the lightest chargino and the lightest neutralino occurs, allowing for scalars with masses well above the n

Wojciech Krolikowski

As a contribution to the hypothesis of mixing of three active neutrinos with, at least, one sterile neutrino, we report on a simple $4\times4$ texture whose $3\times3$ part arises from the popular bimaximal texture for three active neutrinos $ν_e,ν_μ,ν_τ$, where $c_{12}=1/\sqrt{2} = s_{12}$, $c_{23} = 1/\sqrt{2} = s_{23}$ and $s_{13} = 0$. Such a $3\times 3$

Ivan Horvath, Nathan Isgur, John McCune, H. B. Thacker

The low-lying eigenmodes of the Dirac operator associated with typical gauge field configurations in QCD encode, among other low-energy properties, the physics behind the solution to the $U_A(1)$ problem (i.e. the origin of the $η&#39;$ mass), the nature of spontaneous chiral symmetry breaking, and the physics of string-breaking, quark-antiquark pair product

Masako Iwasaki, Toshinori Abe

The North American Linear Collider Detector group has developed a simulation program package based on the ROOT system. The package consists of Fast simulation, the reconstruction of the Full simulated data, and physics analysis utilities.

Masako Iwasaki

We report a study of top-quark reconstruction in $e^+e^- \rightarrow t\bar{t}$ events at a 500 GeV linear collider using the LCD Fast simulator. The initial study of top-quark anomalous couplings is also reported. The final states of 4 jets and lepton as well as 6 jets are used. Using the 4 jets and lepton final state, we estimate the preliminary sensitiviti

Gerardo Ganis

The negative outcome of searches for supersymmetry performed at LEP have been used to derive indirect constraints on the parameters of the most plausible supersymmetric candidates for cold dark matter, in particular for the lightest neutralino. We review the basic ideas leading to the present lower limit on the lightest neutralino mass of about 37 GeV, with

K. Wozniak

PHOBOS is one of four experiments studying the Au-Au interactions at RHIC. The data collected during the first few weeks after the RHIC start-up, using the initial configuration of the PHOBOS detector, were sufficient to obtain the first physics results for the most central collisions of Au nuclei at the center of mass energy of 56 and 130 AGeV. The pseudora

A. Faus-Golfe, M. Haguenauer, J. Velasco

A precise measurement of the total cross section and the coulomb scattering at the LHC requires the observation of elastically scatteredparticles at extremely small angles (14 microrad, -t < 0.01 GeV**2 for the first case; 3 microrad, -t<0.0006 GeV**2 for the second one). In this paper a very high-beta insertion optics is presented. A feasibility study, incl

Kevin T. Pitts

This writeup is an introduction to some of the experimental issues involved in performing electroweak and B physics measurements at the Fermilab Tevatron. In the electroweak sector, we discuss W and Z boson cross section measurements as well as the measurement of the mass of the W boson. For B physics, we discuss measurements of B^0/\bar{B^0} mixing and CP v

D. Bini, R. T. Jantzen

Gravitomagnetic clock effects for circularly rotating orbits in black hole spacetimes are studied from a relative observer point of view, clarifying the roles played by special observer families.

Mirta S. Iriondo, Oscar A. Reula

We perform a numerical free evolution of a selfgravitating, spherically symmetric scalar field satisfying the wave equation. The evolution equations can be written in a very simple form and are symmetric hyperbolic in Eddington-Finkelstein coordinates. The simplicity of the system allow to display and deal with the typical gauge instability present in these

L. Herrera, D. Pavon

Contrary to what is asserted in a recent paper by Kostadt and Liu (&#34;Causality and stability of the relativistic diffusion equation&#34;), experiments can tell apart (and in fact do) hyperbolic theories from parabolic theories of dissipation. It is stressed that the existence of a non--negligible relaxation time does not imply for the system to be out of

Rafael A. Vera

From the equivalence principle and true gravitational (G) time dilation experiments it is concluded that ``matter is not invariable after a change of relative position with respect to other bodies&#39;&#39;. As a general principle (GP), such variations cannot be locally detected because the basic parameters of all of the &#39;well-defined parts&#39; of the i

J. Borg

We present a new and general Monte Carlo iteration method for generalized ensembles. It consists of two elements: (1) a simple algorithm to distinguish between distributions arising from respectively equilibrium- and non-equilibrium processes, and (2) a selfconsistent maximum-likelyhood estimation of the unknown thermodynamic quantities, based on the informa

Raphael Duprat, C. Bourbonnais

The interference between spin-density-wave and superconducting instabilities in quasi-one-dimensional correlated metals is analyzed using the renormalization group method. At the one-loop level, we show how the interference leads to a continuous crossover from a spin-density-wave state to unconventional superconductivity when deviations from perfect nesting

J. E. Hirsch

Photoemission and optical experiments indicate that the transition to superconductivity in cuprates is an &#39;undressing&#39; transition . In photoemission this is seen as a coherent quasiparticle peak emerging from an incoherent background, in optics as violation of the Ferrell-Glover-Tinkham sum rule indicating effective mass reduction of superconducting

H. Schiessel, J. Widom, R. F. Bruinsma, W. M. Gelbart

We consider how beads can diffuse along a chain that wraps them, without becoming displaced from the chain; our proposed mechanism is analogous to the reptation of &#34;stored length&#34; in more familiar situations of polymer dynamics. The problem arises in the case of globular aggregates of proteins (histones) that are wound by DNA in the chromosomes of pl

A. Angrisani Armenio, L. V. Mercaldo, S. L. Prischepa, M. Salvato

Measurements of the perpendicular upper critical magnetic field H_{c2 \perp}(T) are reported for several Nb/CuMn multilayers. It is found that, despite the magnetic nature of the samples, the data for samples with low Mn percentage in the CuMn layers are simply described by the Werthamer-Helfand-Honenberg theory for conventional type-II superconductors, negl

M. Krech, H. Karl, H. W. Diehl

The effects of free surfaces on the dynamic critical behavior of isotropic Heisenberg ferromagnets are studied via phenomenological scaling theory, field-theoretic renormalization group tools, and high-precision computer simulations. An appropriate semi-infinite extension of the stochastic model J is constructed, the boundary terms of the associated dynamic

H. Schiessel, W. M. Gelbart, R. Bruinsma

We present a theoretical analysis of the structural and mechanical properties of the 30-nm chromatin fiber. Our study is based on the two-angle model introduced by Woodcock et al. (Woodcock, C. L., S. A. Grigoryev, R. A. Horowitz, and N. Whitaker. 1993. PNAS 90:9021-9025) that describes the chromatin fiber geometry in terms of the entry-exit angle of the nuc

Pietro Cicuta, Ian Hopkinson

We have carried out experiments to probe the static and dynamic interfacial properties of $β$--casein monolayers spread at the air-buffer interface, and analysed these results in the context of models of weak polyampholytes. Measurements have been made systematically over a wide range of ionic strength and pH. In the semi-dilute regime of surface concentrati

Alexander Altland, Rainer Merkt

Systems with bond disorder are defined through lattice Hamiltonians that are of pure nearest neighbour hopping type, i.e. do not contain on-site contributions. Previous analyses based on the Dorokhov-Mello-Pereyra-Kumar (DMPK) transfer matrix technique have shown that both spectral and transport properties of quasi one-dimensional systems belonging to this c

Yoshihiro Nishiyama

Quantum string, which was brought into discussion recently as a model for the stripe phase in doped cuprates, is simulated by means of the density-matrix-renormalization-group method. String collides with adjacent neighbors, as it wonders, owing to quantum zero-point fluctuations. The energy cost due to the collisions is our main concern. Embedding a quantum

Sreejith Sukumaran, Udo Seifert

We describe the dynamics of three-dimensional fluid vesicles in steady shear flow in the vicinity of a wall. This is analyzed numerically at low Reynolds numbers using a boundary element method. The area-incompressible vesicle exhibits bending elasticity. Forces due to adhesion or gravity oppose the hydrodynamic lift force driving the vesicle away from a wal

G. Migliorini, V. G. Rostiashvili, T. A. Vilgis

A variational approach is considered to calculate the free energy and the conformational properties of a polyelectrolyte chain in $d$ dimensions. We consider in detail the case of pure Coulombic interactions between the monomers, when screening is not present, in order to compute the end-to-end distance and the asymptotic properties of the chain as a functio

Lei Wang, Bing-Hong Wang, Bambi Hu

We propose and study a new one-dimensional traffic flow cellular automaton (CA) model of high speed vehicles with the Fukui-Ishibashi-type acceleration for all cars and the Nagel-Schreckenberg-type (NS) stochastic delay only for the cars following the trail of the car ahead. The main difference in the delay scenario between the new model and the NS model is

M. Lavagna

We give a general introduction to quantum phase transitions in strongly-correlated electron systems. These transitions which occur at zero temperature when a non-thermal parameter $g$ like pressure, chemical composition or magnetic field is tuned to a critical value are characterized by a dynamic exponent $z$ related to the energy and length scales $Δ$ and $

Christian Hainzl, Robert Seiringer

By means of a generalization of the Fefferman-de la Llave decomposition we derive a general lower bound on the interaction energy of one-dimensional quantum systems. We apply this result to a specific class of lowest Landau band wave functions.

H. Kitatani, A. Sinada

In response to the comment made by Dr. Shirakura {\it et al} (cond-mat/0011235), we explain that their scaling forms of the order parameter distribution are inadequate. We then present an appropriate scaling form of the order parameter distribution, which gives a good scaling plot of the order parameter distribution itself and also gives consistent results w

J. L. Roberts, N. R. Claussen, S. L. Cornish, E. A. Donley

The point of instability of a Bose-Einstein Condensate (BEC) due to attractive interactions was studied. Stable 85-Rb BECs were created and then caused to collapse by slowly changing the atom-atom interaction from repulsive to attractive using a Feshbach resonance. At a critical value, an abrupt transition was observed in which atoms were ejected from the co

V. Luridiana, M. Peimbert

We compute photoionization models for the giant extragalactic H II region NGC 5461, and compare their predictions to several observational constraints. Since we aim at reproducing not only the global properties of the region, but its local structure also, the models are constrained to reproduce the observed density profile, and our analysis takes into consid

R. C. Hartman, M. Boettcher

Of the blazars detected by EGRET in GeV gamma rays, 3C 279 is not only the best-observed by EGRET, but also one of the best-monitored at lower frequencies. We have assembled eleven spectra, from GHz radio through GeV gamma rays, from the time intervals of EGRET observations. Although some of the data have appeared in previous publications, most are new, incl

D. G. Korycansky, Gregory Laughlin, Fred C. Adams

The Sun&#39;s gradual brightening will seriously compromise the Earth&#39;s biosphere within ~ 1E9 years. If Earth&#39;s orbit migrates outward, however, the biosphere could remain intact over the entire main-sequence lifetime of the Sun. In this paper, we explore the feasibility of engineering such a migration over a long time period. The basic mechanism us

L. M. Macri, D. Calzetti, W. L. Freedman, B. K. Gibson

We present the results of near-infrared observations of extragalactic Cepheids made with the Near Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope. The variables are located in the galaxies IC 1613, IC 4182, M 31, M 81, M 101, NGC 925, NGC 1365, NGC 2090, NGC 3198, NGC 3621, NGC 4496A and NGC 4536. All fields were observed in

K. T. Lewis, D. N. Burrows, J. A. Nousek, G. P. Garmire

We present the preliminary results of a 40.8 ks Chandra ACIS observation of the young supernova remnant (SNR) N103B located in the Large Magellanic Cloud. The image reveals structure at the sub-arcsecond level, including several bright knots and filamentary structures. The remnant has the characteristic spectrum of a Type Ia SNR, containing strong lines of F

L. M. Macri, K. Z. Stanek, D. D. Sasselov, M. Krockenberger

The DIRECT project aims to determine direct distances to two important galaxies in the cosmological distance ladder - M31 and M33 - using detached eclipsing binaries (DEBs) and Cepheids. We present the results of the first large-scale CCD-based search for variables in M33. We have observed two fields located in the central region of M33 for a total of 95 nig

I. A. Bonnell, C. J. Clarke, M. R. Bate, J. E. Pringle

We present a simple physical mechanism that can account for the observed stellar mass spectrum for masses $\ms \simgreat 0.5 \solm$. The model depends solely on the competitive accretion that occurs in stellar clusters where each star&#39;s accretion rate depends on the local gas density and the square of the accretion radius. In a stellar cluster, there are

J. B. Holberg, Terry D. Oswalt, E. M. Sion

The most recent version of the Catalog of Spectroscopically Identified White Dwarfs lists 2249 white dwarf stars. Among these stars are 118 white dwarfs that have either reliable trigonometric parallaxes or color-based distance moduli which place them at a distance within 20 pc of the Sun. Most of these nearby white dwarfs are isolated stars, but 35 (30 % of

Ranjeev Misra, Ronald E. Taam

The effect of a possible hydrodynamical wind on the nature of hot accretion disk solutions is studied. It is found that the advection dominated branch, in the presence of a wind, maintains the self-similar solution for the disk structure with the temperature, $θ\propto 1/r$, optical depth $τ\propto r^{P-1/2}$ and accretion rate $\dot m \propto r^P$. Based on

A. Ankay, L. Kaper, J. H. J. de Bruijne, J. Dewi

Based on its Hipparcos proper motion, we propose that the high-mass X-ray binary HD153919/4U1700-37 originates in the OB association Sco OB1. At a distance of 1.9 kpc the space velocity of 4U1700-37 with respect to Sco OB1 is 75 km/s. This runaway velocity indicates that the progenitor of the compact X-ray source lost about 7 Msun during the (assumed symmetr