January 2003 arXiv papers — page 9

Kunihiro Kojima, Holger F. Hofmann, Shigeki Takeuchi, Keiji Sasaki

The nonlinear photon-photon interaction mediated by a single two-level atom is studied theoretically based on a one-dimensional model of the field-atom interaction. This model allows us to determine the effects of an atomic nonlinearity on the spatiotemporal coherence of a two photon state. Specifically, the complete two photon output wave function can be ob

Min-Young Choi, Choonkyu Lee

For a quantum mechanical system with broken supersymmetry, we present a simple method of determining the ground state when the corresponding energy eigenvalue is sufficiently small. A concise formula is derived for the approximate ground state energy in an associated, well-separated, asymmetric double-well-type potential. Our discussion is also relevant for

A. M. Karick, M. J. Drinkwater, M. D. Gregg

We present BVI photometry of 190 galaxies in the central region of the Fornax Cluster observed with the Michigan Curtis Schmidt Telescope. The cluster members exhibit a strong surface brightness-magnitude relation in our data: both giant and dwarf ellipticals decrease in surface brightness as luminosity decreases. However the surface brightness-magnitude rel

Congwu Cui, Trevor A. Tyson

In Pr$_{0.7}$Ca$_{0.3}$MnO$_{3}$, pressure induces reentrant magnetic and electronic state changes in the range 1 atm to $\sim$ 6 GPa. The metal-insulator and magnetic transition temperatures coincide from $\sim$1 to 5 GPa, decouple outside of this range and do not change monotonically with pressure. The effects may be explained by pressure tuned competition

Jae-Weon Lee, Eok Kyun Lee, Yong Wook Chung, Hai-Woong Lee

A quantum cryptography scheme based on entanglement between a single particle state and a vacuum state is proposed. The scheme utilizes linear optics devices to detect the superposition of the vacuum and single particle states. Existence of an eavesdropper can be detected by using a variant of Bell's inequality.

V. V. Dobrovitski, H. A. De Raedt

We demonstrate that the Chebyshev expansion method is a very efficient numerical tool for studying spin-bath decoherence of quantum systems. We consider two typical problems arising in studying decoherence of quantum systems consisting of few coupled spins: (i) determining the pointer states of the system, and (ii) determining the temporal decay of quantum o

Luiz Davidovich

This paper discusses work developed in recent years, in the domain of quantum optics, which has led to a better understanding of the classical limit of quantum mechanics. New techniques have been proposed, and experimentally demonstrated, for characterizing and monitoring in real time the quantum state of an electromagnetic field in a cavity. They allow the

Gregg Jaeger, Mihail Teodorescu-Frumosu, Alexander Sergienko, Bahaa E. A. Saleh

We consider the Minkowskian norm of the n-photon Stokes tensor, a scalar invariant under the group realized by the transformations of stochastic local quantum operations and classical communications (SLOCC). This invariant is offered as a candidate entanglement measure for n-qubit states and discussed in relation to measures of quantum state entanglement for

Wojciech Hubert Zurek

Quantum discord was proposed as an information theoretic measure of the ``quantumness'' of correlations. I show that discord determines the difference between the efficiency of quantum and classical Maxwell's demons -- that is, entities that can or cannot measure nonlocal observables or carry out conditional quantum operations -- in extracting wo

R. W. Rendell, A. K. Rajagopal

An exact density matrix of a phase-damped Jaynes - Cummings model (JCM) with entangled Bell-like initial states formed from a model two-state atom and sets of adjacent photon number states of a single mode radiation field is presented. The entanglement of the initial states and the subsequent time evolution is assured by finding a positive lower bound on the

Dominik Janzing, Thomas Beth

We consider Hamiltonian quantum systems with energy bandwidth ΔE and show that each measurement that determines the time up to an error Δt generates at least the entropy (\hbar/(Δt ΔE))^2/2. Our result describes quantitatively to what extent all timing information is quantum information in systems with limited energy. It provides a lower bound on the dissipa

Wenhua Hai, Chaohong Lee, Guishu Chong

We find a set of new exact solutions of a quantum harmonic oscillator, which describes some wave-packet trains with average energy being proportional to both the quantum level and classical energy of the oscillator. Center of the wave-packet trains may oscillate like a classical harmonic oscillator of frequency $ω$. Width and highness of the trains may chang

H. F. Powell, S. R. de Echaniz, E. S. Phillips, D. M. Segal

We report a study of the axialisation and laser cooling of single ions and small clouds of ions in a Penning trap. A weak radiofrequency signal applied to a segmented ring electrode couples the magnetron motion to the cyclotron motion, which results in improved laser cooling of the magnetron motion. This allows us to approach the trapping conditions of a Pau

M. Ignaccolo, P. Allegrini, P. Grigolini, P. Hamilton

This paper is devoted to the problem of statistical mechanics raised by the analysis of an issue of sociological interest: the teen birth phenomenon. It is expected that these data are characterized by correlated fluctuations, reflecting the cooperative properties of the process. However, the assessment of the anomalous scaling generated by these correlation

Dimitri Kusnezov, W. Erich Ormand

The development of nuclear shapes under the extreme conditions of high spin and/or temperature is examined. Scaling properties are used to demonstrate universal properties of both thermal expectation values of nuclear shapes as well as the minima of the free energy, which can be used to understand the Jacobi transition. A universal correlation between the wi

A. Sulaksono, T. Buervenich, J. A. Maruhn, P. -G. Reinhard

We show that formally for the standard ansatz relativistic point-coupling mean-field (RMF-PC) model a lagrangian density L is not equivalent in Hartree and Hartree-Fock approximations. The equivalency can be achieved only if we use a ``complete'' ansatz at the cost of introducing new parameters in the model. An approximate treatment of the exchange t

A. M. Moro, R. Crespo, F. Nunes, I. J. Thompson

The relevance of the continuum effects in transfer reactions is discussed in conection with the determination of observables of astrophysical interest. In particular, we examine the validity of the Distorted Wave Born Approximation (DWBA) as a tool to extract the astrophysical \emph{(S_{17}(0))} factor. For this purpose, we present calculations for the react

G. Verde, P. Danielewicz, W. G. Lynch, D. A. Brown

Imaging technique is applied to two-proton correlation functions to extract quantitative information about the space-time properties of the emitting source and about the fraction of protons that can be attributed to fast emission mechanisms. These new analysis techniques resolve important ambiguities that bedeviled prior comparisons between measured correlat

Boris Gutkin

The plane wave decomposition method (PWDM) is one of the most popular strategies for numerical solution of the quantum billiard problem. The method is based on the assumption that each eigenstate in a billiard can be approximated by a superposition of plane waves at a given energy. By the classical results on the theory of differential operators this can ind

Lucian-Cornel Crasovan, Yaroslav V. Kartashov, Dumitru Mihalache, Lluis Torner

We show how to generate robust self-sustained clusters of soliton bullets-spatiotemporal (optical or matter-wave) solitons. The clusters carry an orbital angular momentum being supported by competing nonlinearities. The "atoms" forming the "molecule" are fully three-dimensional solitons linked via a staircase-like macroscopic phase. Recent pr

Brendan Hassett, Yuri Tschinkel

Consider the Fulton-MacPherson configuration space of $n$ points on $¶^1$, which is isomorphic to a certain moduli space of stable maps to $¶^1$. We compute the cone of effective ${\mathfrak S}_n$-invariant divisors on this space. This yields a geometric interpretation of known asymptotic formulas for the number of integral points of bounded height on compac

Vladimir G. Troitsky

We extend the method of minimal vectors to arbitrary Banach spaces. It is proved, by a variant of the method, that certain quasinilpotent operators on arbitrary Banach spaces have hyperinvariant subspaces.

David Wolpert, Kagan Tumer, Esfandiar Bandari

We consider the problem of designing a set of computational agents so that as they all pursue their self-interests a global function G of the collective system is optimized. Three factors govern the quality of such design. The first relates to conventional exploration-exploitation search algorithms for finding the maxima of such a global function, e.g., simu

Mario Bonk, Bruce Kleiner

The hyperbolic plane admits a quasi-isometric embedding into a hyperbolic group if and only if the group is not virtually free.

Serkan Hosten, Bernd Sturmfels

We determine the maximal gap between the optimal values of an integer program and its linear programming relaxation, where the matrix and cost function are fixed but the right hand side is unspecified. Our formula involves irreducible decomposition of monomial ideals. The gap can be computed in polynomial time when the dimension is fixed.

Jaap Top

We present a table containing the maximal number of rational points on a genus 3 curve over a field of cardinality q, for all q<100. Also, some remarks on Frobenius non-classical quartics over finite fields are given.

Anne-Marie Simon, Jan R. Strooker

Over a noetherian local ring certain minimal finite free resolutions possess a property which we call stiffness. This calls to mind the Buchsbaum-Eisenbud criterion for exactness. Yet we only prove stiffness over equicharacteristic rings. However, Hochster&#39;s Canonical Element Conjecture is shown to be true for every ring with a fixed prime residual chara

Marian Aprodu, Claire Voisin

We use Green&#39;s canonical syzygy conjecture for generic curves to prove that the Green-Lazarsfeld gonality conjecture holds for generic curves of genus g, and gonality d, if $g/3<d<[g/2]+2$.

Stephen Semmes

There seems to be quite a bit of room for interesting things related to surfaces M in C^m with real dimension m which are totally real and aspects of several complex variables on C^m around M. A basic case occurs when m = 1, with Cauchy integral operators along curves, holomorphic functions on the complements of curves, and so on. In the present article we b

Nguyen Tien Zung

This small note has been withdrawn by the author. The main result of the note, with a corrected proof written in collaboration with a collegue, will be part of a joint work.

Alf Onshuus

We develop a new notion of independence suggested by Scanlon (th-independence). We prove that in a large class of theories (which includes all simple theories) this notion has many of the properties needed for an adequate geometric structure in these models. We also prove that this definition agrees with the usual independence notions in stable, supersimple

Jeffrey F. Brock

We introduce a coarse combinatorial description of the Weil-Petersson distance d_WP(X,Y) between two finite area hyperbolic Riemann surfaces X and Y. The combinatorics reveal a connection between Riemann surfaces and hyperbolic 3-manifolds conjectured by Thurston: the volume of the convex core of the quasi-Fuchsian manifold Q(X,Y) with X and Y in its boundar

Andrea Posilicano

Let $A_\N$ be the symmetric operator given by the restriction of $A$ to $\N$, where $A$ is a self-adjoint operator on the Hilbert space $\H$ and $\N$ is a linear dense set which is closed with respect to the graph norm on $D(A)$, the operator domain of $A$. We show that any self-adjoint extension $A_Θ$ of $A_\N$ such that $D(A_Θ)\cap D(A)=\N$ can be additive

James T. Liu, Leopoldo A. Pando Zayas, Diana Vaman

We investigate the possibility of having an event horizon within several classes of metrics that asymptote to the maximally supersymmetric IIB plane wave. We show that the presence of a null Killing vector (not necessarily covariantly constant) implies an effective separation of the Einstein equations into a standard and a wave component. This feature may be

M Luebcke, A. J. Niemi, K. Torokoff

We construct a classical mechanics Hamiltonian which exhibits spontaneous symmetry breaking akin the Coleman-Weinberg mechanism, dimensional transmutation, and asymptotically free self-similarity congruent with the beta-function of four dimensional Yang-Mills theory. Its classical equations of motion support stable periodic orbits and in a three dimensional

V. Elias, D. G. C. McKeon, T. G. Steele

We discuss the application of the method of characteristics to the renormalization-group equation for the perturbative QCD series within the electron-positron annihilation cross-section. We demonstrate how one such renormalization-group improvement of this series is equivalent to a closed-form summation of the first four towers of renormalization-group acces

Jürgen Fuchs, Ingo Runkel, Christoph Schweigert

Affine Kac-Moody algebras give rise to interesting systems of differential equations, so-called Knizhnik-Zamolodchikov equations. The monodromy properties of their solutions can be encoded in the structure of a modular tensor category on (a subcategory of) the representation category of the affine Lie algebra. We discuss the relation between these solutions

Bruce A. Bassett, Monica Borunda, Marco Serone, Shinji Tsujikawa

We study string-gas cosmology in dilaton gravity, inspired by the fact that it naturally arises in a string theory context. Our main interest is the thermodynamical treatment of the string-gas and the resulting implications for the cosmology. Within an adiabatic approximation, thermodynamical equilibrium and a small, toroidal universe as initial conditions,

Yoshiki Hiraoka

We study the noncommutative version of the extended ADHM construction in the eight dimensional U(1) Yang-Mills theory. This construction gives rise to the solutions of the BPS equations in the Yang-Mills theory, and these solutions preserve at least 3/16 of supersymmetries. In a wide subspace of the extended ADHM data, we show that the integer $k$ which appe

Rabin Banerjee

We propose an exact expression for the unintegrated form of the star gauge invariant axial anomaly in an arbitrary even dimensional gauge theory. The proposal is based on the inverse Seiberg-Witten map and identities related to it, obtained earlier by comparing Ramond-Ramond couplings in different decsriptions. The integrated anomalies are expressed in terms

Sergiu I. Vacaru

We synthesize and extend the previous ideas about appearance of both noncommutative and Finsler geometry in string theory with nonvanishing B--field and/or anholonomic (super) frame structures \cite{vstring,vstr2,vnonc,vncf}. There are investigated the limits to the Einstein gravity and string generalizations containing locally anisotropic structures modeled

Ghenadie N. Mardari

The hypothesis of brane-embedded matter appears to gain increasing credibility in astrophysics. However, it can only be truly successful if its implications on particle interaction are consistent with existing knowledge. This letter focuses on the issue of optical interference, and shows that at least one brane-world model can offer plausible interpretations

Carl E. Carlson, Chueng-Ryong Ji

We analyze the current matrix elements in the general collinear (Breit) frames and find the relation between the ordinary (or canonical) helicity amplitudes and the light-front helicity amplitudes. Using the conservation of angular momentum, we derive a general angular condition which should be satisfied by the light-front helicity amplitudes for any spin sy

Yvonne Y. Y. Wong

We consider the implications of a violation of the equivalence principle or of Lorentz invariance in the neutrino sector for the T-asymmetry $ΔP_T \equiv P(ν_α \to ν_β) - P(ν_β \to ν_α)$ in a three-flavour framework. We find that additional mixing due to these mechanisms, while obeying all present bounds, can lead to a substantial enhancement, suppression, a

Hisakazu Minakata, Hiroshi Nunokawa, Stephen Parke

We present a general formalism for extracting information on the fundamental parameters associated with neutrino masses and mixings from two or more long baseline neutrino oscillation experiments. This formalism is then applied to the current most likely experiments using neutrino beams from the Japan Hadron Facility (JHF) and Fermilab&#39;s NuMI beamline. D

Ph. de Forcrand, O. Philipsen

We review our results for the QCD phase diagram at baryonic chemical potential mu_B \leq pi T. Our simulations are performed with an imaginary chemical potential mu_I for which the fermion determinant is positive. For 2 flavors of staggered quarks, we map out the phase diagram and identify the pseudo-critical temperature T_c(mu_I). For mu_I/T \leq pi/3, this

A. Kurylov, M. J. Ramsey-Musolf, S. Su

We compute the supersymmetric (SUSY) contributions to neutrino (antineutrino)-nucleus deep inelastic scattering in the Minimal Supersymmetric Standard Model (MSSM). We consider the ratio of neutral current to charged current cross sections, $R_ν$ and $R_{\bar ν}$, and compare with the deviations of these quantities from the Standard Model predictions implied

G. De Lellis, P. Migliozzi, P. Strolin

Emulsions have started particle physics with the discovery of natural radioactivity by Becquerel in 1896. The development of the ``nuclear emulsions&#39;&#39; made it possible to detect tracks of single particle and to perform detailed measurements of their interactions. The discovery of the pion in 1947 was the first, spectacular demonstration of their uniq

Andrew G. Akeroyd, Marco A. Diaz

We propose new production mechanisms for light fermiophobic Higgs bosons ($h_f$) with suppressed couplings to vector bosons ($V$) at the Fermilab Tevatron. These mechanisms (e.g. $qq&#39;\to H^\pm h_f$) are complementary to the conventional process $qq&#39;\to Vh_f$, which suffers from a strong suppression of $1/\tan^2β$ in realistic models with a $h_f$. The

Enrique Ruiz Arriola, Wojciech Broniowski

We propose a spectral quark model which can be applied to low energy hadronic physics. The approach is based on a generalization of the Lehmann representation of the quark propagator. We work at the one-quark-loop level. Electromagnetic and chiral invariance are ensured with help of the gauge technique which provides particular solutions to the Ward-Takahash

Jean-Paul Blaizot, Edmond Iancu, Urko Reinosa

We discuss the renormalizability of Phi-derivable approximations in scalar phi^4 theory in four dimensions. The formalism leads to self-consistent equations for the 2-point and the 4-point functions which are plagued by ultraviolet divergences. Through a detailed analysis of the one and two-loop self-energy skeletons, we show that both equations can be renor

N. Armesto, C. A. Salgado

Different approaches to gluon shadowing at small x are reviewed. Some available results relevant for RHIC and LHC are compared.

Hai-Yang Cheng

Cabibbo-allowed charmed meson decays into a pseudoscalar meson and an axial-vector meson are studied. The charm to axial-vector meson transition form factors are evaluated in the Isgur-Scora-Grinstein-Wise quark model. The dipole momentum dependence of the $D\to K$ transition form factor and the presence of a sizable long-distance $W$-exchange are the two ke

R. Kirschner

We demonstrate the effective action scheme for the leading parton interactions and discuss the symmetry properties. The interaction kernels are particular cases of conformal symmetric two-particle kernels. There is a direct relation to the conformal symmetric rational solution of the Yang-Baxter equation.

Marco A. Diaz, Douglas A. Ross

We calculate the radiative corrections to helicity amplitudes for chargino production in electron-positron collisions. We include all weak self-energy, triangle, and box diagrams, and find that the three are important and should be included. We present results in the form of differential cross-sections for four supersymmetry benchmark models, and find usuall

Jason C. Webb

Fermilab Experiment 866 has performed an absolute measurement of continuum dimuon (Drell-Yan) cross sections in 800-GeV/c $pp$ and $pd$ interactions. Results differential in the mass, Feynman-$x$ ($x_F$) and transverse momenta ($p_T$) of the dimuon pairs are reported. These results represent the most extensive study of the Drell-Yan process to date, based on

F. J. Burnell, J. J. Malecki, R. B. Mann, T. Ohta

We consider the problem of three body motion for a relativistic one-dimensional self-gravitating system. After describing the canonical decomposition of the action, we find an exact expression for the 3-body Hamiltonian, implicitly determined in terms of the four coordinate and momentum degrees of freedom in the system. Non-relativistically these degrees of

S. Deser

I provide a very brief sketch of some of Dirac&#39;s interests and work in gravity, particularly his Hamiltonian formulation of Einstein&#39;s theory and its relation to his earlier research.

Alexander B. Balakin, Winfried Zimdahl

We investigate a relativistic self-interacting gas in the field of an external {\it pp} gravitational wave. Based on symmetry considerations we ask for those forces which are able to compensate the imprint of the gravitational wave on the macroscopic 4-acceleration of the gaseous fluid. We establish an exactly solvable toy model according to which the statio

Lee Samuel Finn

A recent report on gravitational wave detector data from the NAUTILUS and EXPLORER detector groups claims a statistically significant excess of coincident events when the detectors are oriented in a way that maximizes their sensitivity to gravitational wave sources in the galactic plane. While not claiming a detection of gravitational waves, they do strongly

Jean-Luc Brylinski, Ranee Brylinski

Immanants are polynomial functions of n by n matrices attached to irreducible characters of the symmetric group S_n, or equivalently to Young diagrams of size n. Immanants include determinants and permanents as extreme cases. Valiant proved that computation of permanents is a complete problem in his algebraic model of NP theory, i.e., it is VNP-complete. We

Torsten Schaub, Kewen Wang

We provide a semantic framework for preference handling in answer set programming. To this end, we introduce preference preserving consequence operators. The resulting fixpoint characterizations provide us with a uniform semantic framework for characterizing preference handling in existing approaches. Although our approach is extensible to other semantics by

Pierre Le Doussal, Kay Joerg Wiese

Recently we constructed a renormalizable field theory up to two loops for the quasi-static depinning of elastic manifolds in a disordered environment. Here we explore further properties of the theory. We show how higher correlation functions of the displacement field can be computed. Drastic simplifications occur, unveiling much simpler diagrammatic rules th

H. Cao, Xunya Jiang, Y. Ling, J. Y. Xu

We studied experimentally and theoretically the interaction of lasing modes in random media. In a homogeneously broadened gain medium, cross gain saturation leads to spatial repulsion of lasing modes. In an inhomogeneously broadened gain medium, mode repulsion occurs in the spectral domain. Some lasing modes are coupled through photon hopping or electron abs

Kagan Tumer, David Wolpert

In this letter we summarize some recent theoretical work on the design of collectives, i.e., of systems containing many agents, each of which can be viewed as trying to maximize an associated private utility, where there is also a world utility rating the behavior of that overall system that the designer of the collective wishes to optimize. We then apply al

J. Cleve, M. Greiner, K. R. Sreenivasan

The two-point correlation function of the energy dissipation, obtained from a one-point time record of an atmospheric boundary layer, reveals a rigorous power-law scaling with intermittency exponent mu=0.20 over almost the entire inertial range of scales. However, for the related integral moment, the power-law scaling is restricted to the upper part of the i

Valeria Del Prete

Recent studies have explored theoretically the ability of populations of neurons to carry information about a set of stimuli, both in the case of purely discrete or purely continuous stimuli, and in the case of multidimensional continuous angular and discrete correlates, in presence of additional quenched disorder in the distribution. An analytical expressio

S. B. Ogale, R. J. Choudhary, J. P. Buban, S. E. Lofland

Occurrence of room temperature ferromagnetism is demonstrated in pulsed laser deposited thin films of Sn1-xCoxO2-d (x<0.3). Interestingly, films of Sn0.95Co0.05O2-d grown on R-plane sapphire not only exhibit ferromagnetism with a Curie temperature close to 650 K, but also a giant magnetic moment of about 7 Bohr-Magneton/Co, not yet reported in any diluted ma

S. N. Kale, S. B. Ogale, S. R. Shinde, M. Sahasrabuddhe

Thin films of 5 % Co doped Cu2O were grown on single crystal (001) MgO substrates by pulsed laser deposition, without and with 0.5 % codoping with Al, V or Zn. Structural, electrical, and magnetic properties were studied. The films showed phase pure character under the chosen optimum growth conditions. Spin glass like behavior was observed in Co doped films

Jeferson J. Arenzon, Yan Levin, Mauro Sellitto

We present an analytical and numerical study of a nonlinear diffusion model which describes density relaxation of loosely packed particles under gravity and weak random (thermal) vibration, and compare the results with Monte Carlo simulations of a lattice gas under gravity. The dynamical equation can be thought of as a local density functional theory for a c

Hagen Kleinert, Ying Jiang

We set up simple harmonic lattice models for elastic fluctuations in bcc and fcc lattices and the excitation of dislocations and disclinations. From these we derive, in a lowest approximation, universal formulas which predict melting temperatures in good agreement with the experiments. This new theory is more precise than Lindemann&#39;s rule by factor 2, an

P. Postorino, A. Congeduti, P. Dore, F. A. Gorelli

A comprehensive understanding of the physical origin of the unique magnetic and transport properties of A_(1-x)A&#39;^xMnO_3 manganites (A = trivalent rare-earth and A&#39; = divalent alkali-earth metal) is still far from being achieved. The complexity of these systems arises from the interplay among several competing interactions of comparable strength. Rec

S. Ostanin, E. Salamatov

First-principles calculation and anharmonic dynamical theory were used in sequence to explain a large excess heat capacity observed in yttria-stabilized zirconia in comparison with the additive rule value. It is found that the excessive shape of heat capacity decays gradually with the Y$_{2}$O$_{3}$ doping when the number of environmentally different O sites

M. G. A. Crawford, P. W. Brouwer, C. W. J. Beenakker

We calculate the weak localization correction in the double crossover to broken time-reversal and spin-rotational symmetry for a disordered microbridge or a short disordered wire using a scattering-matrix approach. Whereas the correction has universal limiting values in the three basic symmetry classes, the functional form of the magnetoconductance is affect

Y. B. Zhu, J. W. Xiong, S. F. Wang, Y. L. Zhou

Superconducting thick films (200$μ$m-300$μ$m) of YBCO have been fabricated successfully on MgO substrates by a new approach. The precursor powders (YBa2Cu3O7-$δ$(Y123)+0.1molY2BaCuO5(Y211)) are placed between two MgO (10mm x 10mm) slices to form sandwich structure. The YBCO thick films have been obtained from the precursors by modified melt growth process. R

Joerg Rottler, Mark O. Robbins

We report on an extensive study of craze formation in glassy polymers. Molecular dynamics simulations of a coarse-grained bead-spring model were employed to investigate the molecular level processes during craze nucleation, widening, and breakdown for a wide range of temperature, polymer chain length $N$, entanglement length $N_e$ and strength of adhesive in

Francois Drolet, Jorge Vinals

A mesoscopic model of a diblock copolymer is used to study the motion of a grain boundary separating two regions of perfectly ordered lamellar structures under an oscillatory but uniform shear flow. The case considered is a grain boundary separating lamellae along the so called parallel orientation (with wavevector parallel to the velocity gradient direction

H. Arodz, R. Pelka

The structure of the half-integer rectilinear disclination line within the framework of the Landau-de Gennes effective theory of nematic liquid crystals is investigated. The consistent perturbative expansion is constructed for the case of $L_2\neq 0$. It turns out that such expansion can be performed around only a discrete subset of an infinite set of the de

D. V. Shopova, T. L. Boyadjiev

We have analyzed the properties of a noncollinear magnetic phase obtained in the mean-field analysis of the model of two coupled Heisenberg subsystems. The domain of its existence and stability is narrow and depends on the ratio between the averaged over nearest neighbours microscopic exchange parameters.

B. I. Halperin, Ady Stern, S. M. Girvin

A bilayer electron system in a strong magnetic field at low temperatures, with total Landau level filling factor nu =1, can enter a strongly coupled phase, known as the (111) phase or the quantum Hall pseudospin-ferromagnet. In this phase there is a large quantized Hall drag resistivity between the layers. We consider here structures where regions of (111) p

F. Calvo

An empirical potential with fluctuating charges is proposed for modelling (MgO)_n clusters in both the molecular (small n) and bulk (n->infty) regimes. Vectorial polarization forces are explicitely taken into account in the self-consistent determination of the charges. Our model predicts cuboid cluster structures, in agreement with previous experimental and

Bo Zhao, Zeng-Bing Chen

We consider the quantum Hall effect induced by magnetic field and rotation, which can drive the Hall samples into the quantum Hall regime and induce fractional excitations. Both the mass and the charge of the Laughlin quasiparticles are predicted to be fractionally quantized. The observable effects induced by rotation are discussed. Based on the usual Hall s

O. Golinelli

We present an analysis of the spectral density of the adjacency matrix of large random trees. We show that there is an infinity of delta peaks at all real numbers which are eigenvalues of finite trees. By exact enumerations and Monte-Carlo simulations, we have numerical estimations of the heights of peaks. In the large tree limit, the sum of their heights is

J. M. Rubi, A. Gadomski

Nonequilibrium thermodynamics formalism is proposed to derive the flux of grainy (bubbles-containing) matter, emerging in a nucleation growth process. Some power and non-power limits, due to the applied potential as well as owing to basic correlations in such systems, have been discussed. Some encouragement for such a discussion comes from the fact that the

E. Bartel, A. Schadschneider, J. Zittartz

We investigate a large class of antiferromagnetic spin-1 chains with nearest neighbour interaction and exactly known matrix product ground state. The spectrum of low-lying excitations is calculated numerically by DMRG and exact diagonalisation. Spin liquid behaviour with an excitation gap is observed meeting the Haldane scenario. Further, we compare properti

S. M. Ashimov, J. G. Chigvinadze

Sharp increase of pinning force was observed at the 3D-2D phase transition in strongly anisotropic high temperature superconductors of the BiPbSrCaCuO system.

Andrei A. Fedorenko

A field-theory approach is used to investigate the &#39;&#39;spin-glass effects&#39;&#39; on the critical behaviour of systems with weak temperature-like quenched disorder. The renormalization group (RG) analysis of the effective Hamiltonian of a model with replica symmetry breaking (RSB) potentials of a general type is carried out in the two-loop approximat

Y. Itoh, T. Machi, C. Kasai, S. Adachi

We studied local electronic states near Zn in optimally doped YBa$_2$(Cu$_{1-x}$Zn_x)$_3$O$_{7-δ}$ and underdoped YBa$_2$(Cu$_{1-x}$Zn_x)$_4$O$_8$ via satellite signals of plane-site Cu(2) nuclear quadrupole resonance (NQR) spectra. From the relative intensity of Cu NQR spectra, the satellite signals are assigned to Zn-neighbor Cu NQR lines. The Cu nuclear s

Jan de Gier, Bernard Nienhuis, Paul A. Pearce, Vladimir Rittenberg

We propose a one-dimensional nonlocal stochastic model of adsorption and desorption depending on one parameter, the adsorption rate. At a special value of this parameter, the model has some interesting features. For example, the spectrum is given by conformal field theory, and the stationary non-equilibrium probability distribution is given by the two-dimens

Taner Yildirim, A. Brooks Harris

We study the coupled rotation-vibration levels of a hydrogen molecule in a confining potential with cylindrical symmetry. We include the coupling between rotations and translations and show how this interaction is essential to obtain the correct degeneracies of the energy level scheme. We applied our formalism to study the dynamics of H$_{2}$ molecules insid

B. Liu, A. Yamilov, Y. Ling, J. Y. Xu

We have studied the dynamic effect of nonlinearity on lasing in disordered medium. The third-order nonlinearity not only changes the frequency and size of lasing modes, but also modifies the laser emission intensity and laser pulse width. When the nonlinear response time is comparable to or longer than the lifetime of the lasing mode, the nonlinearity change

Joshua E. S. Socolar

A fundamental property of any material is its response to a localized stress applied at a boundary. For granular materials consisting of hard, cohesionless particles, not even the general form of the stress response is known. Directed force chain networks (DFCNs) provide a theoretical framework for addressing this issue, and analysis of simplified DFCN model

Kouichi Okunishi, Takashi Tonegawa

We determine the magnetic phase diagram of the antiferromagnetic(AF) zigzag spin chain in the strongly frustrated region, using the density matrix renormalization group method. We find the magnetization plateau at 1/3 of the full moment accompanying the spontaneous symmetry breaking of the translation, the cusp singularities above and/or below the plateau, a

Felix Ritort, Peter Sollich

We review the use of kinetically constrained models (KCMs) for the study of dynamics in glassy systems. The characteristic feature of KCMs is that they have trivial, often non-interacting, equilibrium behaviour but interesting slow dynamics due to restrictions on the allowed transitions between configurations. The basic question which KCMs ask is therefore h

J. H. Debes, J. Ge, C. Mendelowitz, A. Watson

Gaussian aperture pupil masks (GAPMs) can in theory achieve the contrast requisite for directly imaging an extrasolar planet. We outline the process of fabricating and testing a GAPM for use on the Penn State near-IR Imager and Spectrograph (PIRIS) at the Mt. Wilson 100$^{\prime\prime}$ telescope. We find that the initial prototype observations are quite suc

Adriana Gazol, Thierry Passot

This paper is devoted to the study of the gravitational instability of a medium permeated by a uniform magnetic field along which a circularly polarized Alfven wave propagates. We concentrate on the case of perturbations purely transverse to the ambient field by means of direct numerical simulations of the MHD equations and of a linear stability analysis per

E. Churazov, W. Forman, C. Jones, H. Böhringer

We present preliminary results of the XMM-Newton 50 ksec observation of the Perseus cluster. The global east/west asymmetry of the gas temperature and surface brightness distributions, approximately aligned with the chain of bright galaxies, suggests an ongoing merger, although the modest degree of the observed asymmetry certainly excludes a major merger int

Nanyao Lu, George Helou, Michael W. Werner, Harriet L. Dinerstein

We present ISO-PHOT spectra of the regions 2.5-4.9um and 5.8-11.6um for a sample of 45 disk galaxies from the U.S. ISO Key Project on Normal Galaxies. The spectra can be decomposed into three spectral components: (1) continuum emission from stellar photospheres, which dominates the near-infrared (2.5- 4.9um; NIR) spectral region; (2) a weak NIR excess contin

S. Markoff, M. Nowak, S. Corbel, R. Fender

Astrophysical jets exist in both XRBs and AGN, and seem to share common features, particularly in the radio. While AGN jets are known to emit X-rays, the situation for XRB jets is not so clear. Radio jets have been resolved in several XRBs in the low/hard state, establishing that some form of outflow is routinely present in this state. Interestingly, the fla

S. O. Kepler, R. E. Nather, D. E. Winget, A. Nitta

We report 323 hours of nearly uninterrupted time series photometric observations of the DBV star GD 358 acquired with the Whole Earth Telescope (WET) during May 23rd to June 8th, 2000. We acquired more than 232 000 independent measurements. We also report on 48 hours of time-series photometric observations in Aug 1996. We detected the non-radial g-modes cons