November 2005 arXiv papers — page 35

Michael F. Hagan, David Chandler

We develop a class of models with which we simulate the assembly of particles into T1 capsid-like objects using Newtonian dynamics. By simulating assembly for many different values of system parameters, we vary the forces that drive assembly. For some ranges of parameters, assembly is facile, while for others, assembly is dynamically frustrated by kinetic tr

Sergi Valverde, Ricard V. Sole

In a recent paper, Krapivsky and Redner (Phys. Rev. E, 71 (2005) 036118) proposed a new growing network model with new nodes being attached to a randomly selected node, as well to all ancestors of the target node. The model leads to a sparse graph with an average degree growing logarithmically with the system size. Here we present compeling evidence for soft

Salvatore Scellato, Alessio Cardillo, Vito Latora, Sergio Porta

Recent studies have revealed the importance of centrality measures to analyze various spatial factors affecting human life in cities. Here we show how it is possible to extract the backbone of a city by deriving spanning trees based on edge betweenness and edge information. By using as sample cases the cities of Bologna and San Francisco, we show how the obt

Bernhard Rothenstein, Stefan Popescu, George J. Spix

We present a relativistic space-time diagram that displays in true magnitudes the readings (daytimes) of two inertial reference frames clocks. One reference frame is the rest frame for one clock. This diagram shows that two events simultaneous in one reference frames are not compulsory simultaneous in the other frame. This approach has a bi-dimensional chara

Charles F. F. Karney, Jason E. Ferrara, Clay D. Spence

The molecular distributions obtained from canonical Monte Carlo simulations can be used to find an approximate interaction energy. This serves as the basis of a method for estimating the binding free energy for a ligand to a protein which enables the free energy to be used to direct the design of ligands which bind to a protein with high affinity.

Anatole Kenfack, Jan M Rost

The fragmentation of diatomic molecules under a stochastic force is investigated both classically and quantum mechanically, focussing on their dissociation probabilities. It is found that the quantum system is more robust than the classical one in the limit of a large number of kicks. The opposite behavior emerges for a small number of kicks. Quantum and cla

Peter Chudinov

A classic problem of the motion of a point mass (projectile) thrown at an angle to the horizon is reviewed. The air drag force is taken into account with the drag factor assumed to be constant. Analytic approach is used for investigation. Simple analytical formulas are used for the constructing the envelope of the family of the point mass trajectories. The e

M. Barrault, E. Cances, W. W. Hager, C. Le Bris

We introduce a new multilevel domain decomposition method (MDD) for electronic structure calculations within semi-empirical and Density Functional Theory (DFT) frameworks. This method iterates between local fine solvers and global coarse solvers, in the spirit of domain decomposition methods.

Jan Conrad, Fredrik Tegenfeldt

In this note we present studies of coverage and power for confidence intervals for a Poisson process with known background calculated using the Likelihood ratio (aka Feldman & Cousins) ordering with Bayesian treatment of uncertainties in nuisance parameters. We consider both the variant where the Bayesian integration is done in both the numerator and the den

James T. Wheeler

A survey of topics of recent interest in Hamiltonian and Lagrangian dynamical systems, including accessible discussions of regularization of the central force problem; inequivalent Lagrangians and Hamiltonians; constants of central force motion; a general discussion of higher-order Lagrangians and Hamiltonians with examples from Bohmian quantum mechanics, th

K. -H. Becks, P. Gerlach, C. Grah, P. Maettig

The Multi-Chip-Module-Deposited (MCM-D) technique has been used to build hybrid pixel detector assemblies. This paper summarises the results of an analysis of data obtained in a test beam campaign at CERN. Here, single chip hybrids made of ATLAS pixel prototype read-out electronics and special sensor tiles were used. They were prepared by the Fraunhofer Inst

N. Alberola, T. Anthonioz, A. Badertscher, C. Bas

We have developed a high-efficiency pulsed slow positron beam for experiments with orthopositronium in vacuum. The new pulsing scheme is based on a double-gap coaxial buncher powered by an RF pulse of appropriate shape. The modulation of the positron velocity in the two gaps is used to adjust their time-of-flight to a target. This pulsing scheme allows to mi

T. A. Kelf, Y. Sugawara, J. J. Baumberg, M. Abdelsalam

Nanostructured metal surfaces comprised of periodically arranged spherical voids are grown by electrochemical deposition through a self-assembled template. Detailed measurements of the angle- and orientation-dependent reflectivity reveal the spectral dispersion, from which we identify the presence of both delocalized Bragg- and localized Mie-plasmons. These

E. Epelbaum

We derive the leading contribution to the four-nucleon force within the framework of chiral effective field theory. It is governed by the exchange of pions and the lowest-order nucleon-nucleon contact interaction and includes effects due to the nonlinear pion-nucleon couplings and the pion self interactions constrained by the chiral symmetry of QCD. The resu

T. Peitzmann

Different scenarios for the creation of constituent mass in the hadron formation process are discussed. Effects of these may be observable in hadron momentum spectra.

M. Hasegawa, K. Kaneko, T. Mizusaki

We apply a large-scale shell model to the study of proton-rich odd-mass nuclei with $N \approx Z$. Calculations predict unexpected structure in the $^{69}$As nucleus for which a detailed experiment was recently performed. In this odd-proton nucleus, one neutron competes with one proton for occupying the high-$j$ intruder orbit $g_{9/2}$ in the $9/2_1^+$ stat

A. M. Sukhovoj, V. A. Khitrov, Li Chol, Pham Dinh Khang

The values of some functional dependencies of level density and radiative strength functions that reproduce the experimental intensities of the two-step gamma-cascades to the ground and first excited states of 28Al have been determined. It was shown that the assumption about independence of the dipole cascade transitions radiative strength functions on energ

Jan Conrad

The silicon pixel detector (SPD) of the ALICE experiment in preparation at the Large Hadron Collider (LHC) at CERN is designed to provide the precise vertex reconstruction needed for measuring heavy flavor production in heavy ion collisions at very high energies and high multiplicity. The SPD forms the innermost part of the Inner Tracking System (ITS) which

G. Renault, B. S. Nielsen, J. Westergaard, J. J. Gaardhøje

A Large Ion Collider Experiment (ALICE) is the only experiment at the Large Hadron Collider (LHC) dedicated to the study of heavy ion collisions. The Time Projection Chamber (TPC) is the main tracking detector covering the pseudo rapidity range $|η|< 0.9$. It is designed for a maximum multiplicity \dNdy = 8000. The aim of the laser system is to simulate ioni

M. El Baz

A generalized definition of a deformation of the fermionic oscillator (k-fermionic oscillators) is proposed. Two prescriptions for the construction of generalized Grassmann coherent states for this kind of oscillators are derived. The two prescriptions differs in the nature of the generalized Grassmann variables used. While we use Majid&#39;s definition for

Laurent Bruneau, Alain Joye, Marco Merkli

A quantum system $\s$ interacts in a successive way with elements $\ee$ of a chain of identical independent quantum subsystems. Each interaction lasts for a duration $τ$ and is governed by a fixed coupling between $\s$ and $\ee$. We show that the system, initially in any state close to a reference state, approaches a {\it repeated interaction asymptotic stat

Sergiu Moroianu, Mihai Visinescu

We compute the axial anomaly for the Taub-NUT metric on $R^4$. We show that the axial anomaly for the generalized Taub-NUT metrics introduced by Iwai and Katayama is finite, although the Dirac operator is not Fredholm. We show that the essential spectrum of the Dirac operator is the whole real line.

Alexander Zheglov

In this paper we introduce new various generalizations of the classical Kadomtsev-Petviashvili hierarchy in the case of operators in several variables. These generalizations are the candidates for systems that should play the role, analogous to the role of the KP hierarchy in the classical KP theory, in a generalized KP theory. In particular, they should des

Teodora Liliana Dinu

We establish the existence of an entire solution for a class of stationary Schrödinger equations with subcritical discontinuous nonlinearity and lower bounded potential that blows-up at infinity. The abstract framework is related to Lebesgue-Sobolev spaces with variable exponent. The proof is based on the critical point theory in the sense of Clarke and we a

Teodora Liliana Dinu

We study the nonlinear elliptic problem $-Δu=ρ(x)f(u)$ in $\RR^N$ ($N\geq 3$), $\lim\_{|x|\ri\infty}u(x)=\ell$, where $\ell\geq 0$ is a real number, $ρ(x)$ is a nonnegative potential belonging to a certain Kato class, and $f(u)$ has a sublinear growth. We distinguish the cases $\ell>0$ and $\ell=0$ and we prove existence and uniqueness results if the potenti

S. M. Gonek, C. P. Hughes, J. P. Keating

We use a smoothed version of the explicit formula to find an approximation to the Riemann zeta function as a product over its nontrivial zeros multiplied by a product over the primes. We model the first product by characteristic polynomials of random matrices. This provides a statistical model of the zeta function that involves the primes in a natural way. W

Jose F Carinena, Joan-Andreu Lazaro-Cami, Eduardo Martinez

We review the geometric formulation of the second Noether&#39;s theorem in time-dependent mechanics. The commutation relations between the dynamics on the final constraint manifold and the infinitesimal generator of a symmetry are studied. We show an algorithm for determining a gauge symmetry which is closely related to the process of stabilization of constr

Vladimir Vershinin

In his initial paper on braids E.Artin gave a presentation with two generators for an arbitrary braid group. We give analogues of this Artin&#39;s presentation for various generalizations of braids.

Alexandr Grishkov

By analogy with the definition of group with triality we introduce Lie algebra with triality as Lie algebra L wich admits the group of automorphisms S_3={s,r | s^2=r^3=1, srs=r^2} such that for any x\in L we have (x^s-x)+(x^s-x)^r+(x^s-x)^(r^2)=0. We describe the structure of finite dimensional Lie algebra with triality over a field of characteristic 0 and g

Joerg Schuermann, Shoji Yokura

A theory of characteristic classes of vector bundles and smooth manifolds plays an important role in the theory of smooth manifolds. An investigation of reasonable notions of characteristic classes of singular spaces started since a systematic study of singular spaces such as singular algebraic varieties. We make a quick survey of characteristic classes of s

Sophie Huczynska, Gary L. Mullen

Motivated by recent interest in permutation arrays, we introduce and investigate the more general concept of frequency permutation arrays (FPAs). An FPA of length n=m lambda and distance d is a set T of multipermutations on a multiset of m symbols, each repeated with frequency lambda, such that the Hamming distance between any distinct x,y in T is at least d

Mathilde Weill

In this work, we give a description of all sigma-finite measures on the space of rooted compact real trees which satisfy a certain regenerative property. We show that any infinite measure which satisfies the regenerative property is the &#34;law&#34; of a Levy tree, that is, the &#34;law&#34; of a tree-valued random variable that describes the genealogy of a

Valentin Ferenczi

This paper contains results concerning the Borel reduction of the relation $E_0$ of eventual agreement between sequences of 0&#39;s and 1&#39;s, to the relation of permutative equivalence between basic sequences in a Banach space. For more clarity in this abstract, we state these results in terms of classification by real numbers. If $R$ is some (analytic) e

Sandro Mattarei

In this note we determine all power series $F(X)\in 1+X\F_p[[X]]$ such that $(F(X+Y))^{-1} F(X)F(Y)$ has only terms of total degree a multiple of $p$. Up to a scalar factor, they are all the series of the form $F(X)=E_p(cX)\cdot G(X^p)$ for some $c\in\F_p$ and $G(X)\in 1+X\F_p[[X]]$, where $E_p(X)=\exp\big(\sum_{i=0}^{\infty}X^{p^i}/p^i\big)$ is the Artin-Ha

Teodora Liliana Dinu

We consider a class of nonlinear Dirichlet problems involving the $p(x)$--Laplace operator. Our framework is based on the theory of Sobolev spaces with variable exponent and we establish the existence of a weak solution in such a space. The proof relies on the Mountain Pass Theorem.

Teodora Liliana Dinu

We establish existence and multiplicity theorems for a Dirichlet boundary value problem at resonance, which is a nonlinear subcritical perturbation of a linear eigenvalue problem studied by Cuesta. Our framework includes a sign-changing potential and we locate the solutions by using the Mountain Pass lemma and the Saddle Point theorem.

Teodora Liliana Dinu

Let $p$ and $q$ be locally Hölder functions in $\RR^N$, $p>0$ and $q\geq 0$. We study the Emden-Fowler equation $-Δu+ q(x)|\nabla u|^a=p(x)u^{-γ}$ in $\RR^N$, where $a$ and $γ$ are positive numbers. Our main result establishes that the above equation has a unique positive solutions decaying to zero at infinity. Our proof is elementary and it combines the max

Alessandro Berarducci

We give a presentation of various results on zero-groups in o-minimal structures together with some new observations. In particular we prove that if G is a definably connected definably compact group in an o-minimal expansion of a real closed field, then for any maximal definably connected abelian subgroup T of G, G is the union of the conjugates of T. This

Mikhail Karasev

We describe irreducible representations, coherent states and star-products for algebras of integrals of motions (symmetries) of two-dimensional resonance oscillators. We demonstrate how the quantum geometry (quantum Kähler form, metric, quantum Ricci form, quantum reproducing measure) arises in this problem. We specifically study the distinction between the

C. A. M. Peters, J. H. M. Steenbrink

We recall the construction of the Hodge character and we show, using a result due to F. Bittner, that these can be constructed using classical pure Hodge theory only, sideskipping Deligne&#39;s construction of functorial mixed Hodge structures on the cohomology of algberaic varieties. We then give a proof, based on the weak factorization theorem, that the ne

Pedro Nicolas, Manuel Saorin

A TTF-triple $(\mathcal{C},\mathcal{T},\mathcal{F})$ in an abelian category is called &#39;one-sided split&#39; in case either $(\mathcal{C},\mathcal{T})$ or $(\mathcal{T},\mathcal{F})$ is a split torsion theory. In this paper we classify one-sided split TTF-triples in module categories, thus completing Jans&#39; classification of two-sided split TTF-triples

Robert Berman, Johannes Sjoestrand

In this paper we obtain the full asymptotic expansion of the Bergman-Hodge kernel associated to a high power of a holomorphic line bundle with non-degenerate curvature. We also explore some relations with asymptotic holomorphic sections on symplectic manifolds

Roberto Martinez Villa, Manuel Saorin

We show that if $Λ$ is a $n$-Koszul algebra and $E=E(Λ)$ is its Yoneda algebra, then there is a full subcategory $\mathcal{L}_E$ of the category $Gr_E$ of graded $E$-modules, which contains all the graded $E$-modules presented in even degrees, that embeds fully faithfully into the category $C(Gr_Λ)$ of cochain complexes of graded $Λ$-modules. That extends th

Teodora Liliana Dinu

We are concerned with positive solutions decaying to zero at infinity for the logistic equation $-Δu=λ(V(x)u-f(u))$ in $\RR^N$, where $V(x)$ is a variable potential that may change sign, $λ$ is a real parameter, and $f$ is an absorbtion term such that the mapping $f(t)/t$ is increasing in $(0,\infty)$. We prove that there exists a bifurcation non-negative nu

E. Liberman, M. Teicher

In this paper, we prove that the Hurwitz equivalence problem for 1-factorizations in $F_2 \oplus F_2$ is undecidable, and as a consequence, the Hurwitz equivalence problem for $Δ^2$-factorizations in the braid groups $B_n, n\geq 5$ is also undecidable.

Rei Furihata, Mikami Hirasawa, Tsuyoshi Kobayashi

We introduce a new standard form of a Seifert surface $F$. In that standard form, $F$ is obtained by successively plumbing flat annuli to a disk $D$, where the gluing regions are all in $D$. We show that any link has a Seifert surface in the standard form, and thereby present a new way of coding a link. We present an algorithm to read the code directly from

Thomas Alazard

We prove uniform existence results for the full Navier-Stokes equations for time intervals which are independent of the Mach number, the Reynolds number and the Péclet number. We consider general equations of state and we give an application for the low Mach number limit combustion problem introduced by Majda.

Robert A. Cohen, Martin E. Walter

Using a ``3 by 3 matrix trick&#39;&#39; we previously showed that multiplication in a C*-algebra A, an algebraic structure, is determined by the geometry of the C*-algebra of the 3 by 3 matrices with entries from A. As an application of this algebra-geometry duality we now construct an order theoretic based duality theory for all groups which are either loca

D. N. Yetter

The above named paper has been withdrawn. A colleague has observed a gap in the proof of isotopy invariance, which can be repaired by reducing the coefficients (which lie in (1/6)Z) of the antisymmetric kanji with chords incident with more than one component modulo 8Z. An analogous issue arises in considering the effect of orientation reversal in the proof o

Raif Rustamov

L-spaces were introduced by Ozsvath and Szabo using the Heegaard Floer Homology. In the quest for L-spaces we consider links of isolated complete intersection surface singularities. We show that if such a manifold is an L-space, then it is a link of a rational singularity. We also prove that if it is not an L-space then it admits a symplectic filling with $b

Martine Girard, David R. Kohel, Christophe Ritzenthaler

We show that the Weierstrass points of the generic curve of genus $g$ over an algebraically closed field of characteristic 0 generate a group of maximal rank in the Jacobian.

P. Bieliavsky, S. Detournay, M. Rooman, Ph. Spindel

This note is based on a talk given by one of the authors (S. D.) at the &#34;Rencontres Mathématiques de Glanon&#34;, held in Glanon in July 2004. We will first introduce the BTZ black hole, solution of Einstein&#39;s gravity in 2+1 dimensions, and emphasize some remarkable properties of its geometry. We will essentially pay attention to the non-rotating bla

M. R. Setare, F. Darabi

The Casimir stress on a spherical shell in de Sitter signature changing background for massless scalar field satisfying Dirichlet boundary conditions on the shell is calculated. The Casimir stress is calculated for inside and outside of the shell with different backgrounds corresponding to different metric signatures and cosmological constants. An important

Harold Steinacker

The quantization of noncommutative scalar field theory is studied from the matrix model point of view, exhibiting the significance of the eigenvalue distribution. This provides a new framework to study renormalization, and predicts a phase transition in the noncommutative ϕ^4 model. In 4-dimensions, the corresponding critical line is found to terminate at a

Ali H. Chamseddine

The idea of applying the gauge principle to formulate the general theory of relativity started with Utiyama in 1956. I review various applications of the gauge principle applied to different aspects of the gravitational interactions.

Ali H. Chamseddine

I give a brief introduction to particle interactions based on representations of Poincare Lie algebra. This is later generalized to interactions based on representations of the supersymmetry Lie algebra. Globally supersymmetric models with internal symmetry and locally supersymmetric models leading to supergravity theories are presented. I also discuss highe

A. Pinzul, A. Stern

We examine a recent deformation of three-dimensional anti-deSitter gravity based on noncommutative Chern-Simons theory with gauge group $U(1,1)\times U(1,1)$. In addition to a noncommutative analogue of 3D gravity, the theory contains two addition gauge fields which decouple in the commutative limit. It is well known that the level is quantized in noncommuta

Nail R. Khusnutdinov

In the framework of zeta-function approach the Casimir energy for three simple model system: single delta potential, step function potential and three delta potentials is analyzed. It is shown that the energy contains contributions which are peculiar to the potentials. It is suggested to renormalize the energy using the condition that the energy of infinitel

F. Canfora

A Large N expansion for gravity is proposed. The scheme is based on the splitting of the Einstein-Hilbert action into the BF topological action plus a constraint. The method also allows to include matter fields. The relation between matter and non orientable fat graphs in the expansion is stressed; the special role of scalars is shortly discussed. The connec

Meindert van der Meulen, Denes Sexty, Jan Smit, Anders Tranberg

We investigate the development of winding number and Chern-Simons number in a tachyonic transition in the SU(2) Higgs model, motivated by the scenario of cold electroweak baryogenesis. We find that localized configurations with approximately half-integer winding number, dubbed half-knots, play an important role in this process. When the Chern-Simons number a

Walter Grimus

We demonstrate that Abelian family symmetries allow one to enforce texture zeros in arbitrary entries of the fermion mass matrices. Placing zeros in any number of elements of all occurring mass matrices can be done with two alternative methods; one of them utilizes the group Z_n with n sufficiently high. Concentrating on the lepton sector and on neutrino mas

E. Tomasi-Gustafsson, G. I. Gakh

We study the asymptotic behavior of the ratio of Pauli and Dirac electromagnetic nucleon form factors, $F_2/F_1$, in time-like region for different parametrizations built for the space-like region. We investigate how fast the ratio $F_2/F_1$ approaches the asymptotic limits according to the Phragmèn-Lindelöf theorem. We show that the QCD-inspired logarithmic

Noriyuki Oshimo

We discuss the possibility of measuring the generation mixing for the leptons in $e^+e^-$ collision experiments within the framework of the supersymmetric standard model.

Eugene Levin

This is the talk given at ``Gribov-75 Memorial Workshop on Quarks, Hadrons, and Strong Interactions&#34;, May 22-24, 2005, Budapest. Hungary. In this talk we discuss the BFKL Pomeron Calculus and its interrelation with thecolour dipole approach. The two key problems we consider are the probabilistic interpretation of the BFKL Pomeron Calculus and the possibl

Muge Boz

We study the explicit CP violation of the Higgs sector in the next--to--minimal supersymmetric model with a gauge singlet Higgs field. Our numerical predictions show that electric dipole moment of electron lies around the present experimental upper limits. The mass of the lightest Higgs boson is quite sensitive to the CP violating phases in the theory. It is

F. Jugeau, A. Le Yaouanc, L. Oliver, J. -C. Raynal

Within the OPE, we the new sum rules in Heavy Quark Effective Theory in the heavy quark limit and at order 1/m_Q, using the non-forward amplitude. In particular, we obtain new sum rules involving the elastic subleading form factors chi_i(w) (i = 1,2, 3) at order 1/m_Q that originate from the L_kin and L_mag perturbations of the Lagrangian. To the sum rules c

L. Favart, M. V. T. Machado, L. Schoeffel

The skewing factor, defined as the ratio of the imaginary parts of the amplitudes $Im A(γ^* p \to γ^* p)/Im A(γ^* p \to γp)$ is extracted for the first time from the data using recent Deeply Virtual Compton Scattering (DVCS) and the inclusive inelastic cross section measurements at DESY-HERA. The results values are compared to theoretical predictions for NLO

Masataka Fukugita

The roles of massive neutrinos in cosmology -- in leptogenesis and in the evolution of mass density fluctuations -- are reviewed. Emphasis is given to the limit on neutrino mass from these considerations.

U. Baur

I review the status of theoretical calculations relevant for electroweak physics at the Tevatron and LHC and discuss future directions. I also give a brief overview of current electroweak data and discuss future expectations.

Hovhannes R. Grigoryan, Anthony W. Thomas

We consider partially quenched, mixed chiral perturbation theory with staggered sea and Ginsparg-Wilson valence quarks in order to extract a chiral-continuum extrapolation expression for the vector meson mass up to order O(a^2), at one-loop level. Based on general principles, we accomplish the task without explicitly constructing a sophisticated, heavy vecto

Thomas Heinzl, Tobias Kaestner, Andreas Wipf

We determine effective lattice actions for the Polyakov loop using inverse Monte Carlo techniques.

Sanatan Digal, Tetsuo Hatsuda, Munehisa Ohtani

We study thermal phase transitions of color superconductivity by the lattice simulations of the Ginzburg-Landau (GL) effective theory. The theory is equivalent to the SU_ f(3) cross SU_c(3) Higgs model coupled to SU_c(3) color gauge fields. From the eigenvalues of a 3-by-3 gauge-invariant diquark composite, a clear distinction between the 2-flavor color supe

M. D&#39;Elia, A. Di Giacomo, C. Pica

Studying the order of the chiral transition for $N_f=2$ is of fundamental importance to understand the mechanism of color confinement. We present results of a numerical investigation on the order of the transition by use of a novel strategy in finite size scaling analysis. The specific heat and a number of susceptibilities are compared with the possible crit

W. Bietenholz, K. Jansen, K. -I. Nagai, S. Necco

We explore gauge actions for lattice QCD, which are constructed such that the occurrence of small plaquette values is strongly suppressed. By choosing strong bare gauge couplings we arrive at values for the physical lattice spacings of O(0.1 fm). Such gauge actions tend to confine the Monte Carlo history to a single topological sector. This topological stabi

Yvonne Choquet-Bruhat, James W. York

In this article, dedicated to one of the best specialist of the FOSH systems, we couple the Bianchi equations with the equations satisfied by the dynamical acceleration of a charged fluid and the derivatives of the associated Maxwell field.

Rasika R Perera, Tony S Pollock, Thushara D Abhayapala

This paper investigates the limits of information transfer over a fast Rayleigh fading MIMO channel, where neither the transmitter nor the receiver has the knowledge of the channel state information (CSI) except the fading statistics. We develop a scalar channel model due to absence of the phase information in non-coherent Rayleigh fading and derive a capaci

Stephen Luttrell

An operator algebra implementation of Markov chain Monte Carlo algorithms for simulating Markov random fields is proposed. It allows the dynamics of networks whose nodes have discrete state spaces to be specified by the action of an update operator that is composed of creation and annihilation operators. This formulation of discrete network dynamics has prop

Joseph Y. Halpern, Judea Pearl

We propose a new definition of actual cause, using structural equations to model counterfactuals. We show that the definition yields a plausible and elegant account of causation that handles well examples which have caused problems for other definitions and resolves major difficulties in the traditional account.

Mark A. Miller, David J. Wales

We present the structures of putative global potential energy minima for clusters bound by the Stockmayer (Lennard-Jones plus point dipole) potential. A rich variety of structures is revealed as the cluster size and dipole strength are varied. Most remarkable are groups of closed-loop structures with the topology of knots and links. Despite the large number

Doron L. Bergman, Gregory A. Fiete, Leon Balents

We perform a general study of spin ordering on the pyrochlore lattice with a 3:1 proportionality of two spin polarizations. Equivalently, this describes valence bond solid conformations of a quantum dimer model on the diamond lattice. We determine the set of likely low temperature ordered phases, on the assumption that the ordering is weak, i.e the system is

Felix Soto, Lucia Cabo, Jesus Mosqueira, Manuel V. Ramallo

The fluctuation-induced diamagnetism (FD), associated with the presence of precursor Cooper pairs in the normal state, has been measured in lanthanum with dilute magnetic (Pr) and nonmagnetic (Lu) impurities. It is found that while for pure La and La-Lu alloys the FD agrees, as expected, with the theoretical predictions, it is much larger for La-Pr alloys (a

L. C. Chapon, P. G. Radaelli, G. R. Blake, S. Park

The commensurate and incommensurate magnetic structures of the magnetoelectric system YMn$_{2}$O$_{5}$, as determined from neutron diffraction, were found to be spin-density waves lacking a global center of symmetry. We propose a model, based on a simple magneto-elastic coupling to the lattice, which enables us to predict the polarization based entirely on t

Bianca M. Mladek, Dieter Gottwald, Gerhard Kahl, Martin Neumann

We present results from density functional theory and computer simulations that unambiguously predict the occurrence of first-order freezing transitions for a large class of ultrasoft model systems into cluster crystals. The clusters consist of fully overlapping particles and arise without the existence of attractive forces. The number of particles participa

L. Lecren, O. Roubeau, C. Coulon, Yang-Guang Li

Four discrete MnIII/MnII tetra-nuclear complexes with double-cuboidal core were synthesized. dc magnetic measurements show that both Mn2+ - Mn3+ and Mn3+ - Mn3+ magnetic interactions are ferromagnetic in three samples leading to an S = 9 ground state for the Mn4 unit. Furthermore, these complexes are Single-Molecule Magnets (SMMs) clearly showing both therma

Roland Roth, Dirk Gillespie

We demonstrate that two mechanisms used by biological ion channels to select particles by size are driven by entropy. With uncharged particles in an infinite cylinder, we show that a channel that attracts particles is small-particle selective and that a channel that repels water from the wall is large-particle selective. Comparing against extensive density-f

P. M. Ostrovsky, M. V. Feigel&#39;man

The problem of Josephson current through Coulomb-blocked nanoscale superconductor-normal-superconductor structure with tunnel contacts is reconsidered. Two different contributions to the phase-biased supercurrent are identified, which are dominant in the limits of weak and strong Coulomb interaction. Full expression for the free energy valid at arbitrary Cou

Graham C. McNeil-Watson, Nigel B. Wilding

We report a Phase Switch Monte Carlo (PSMC) method study of the freezing line of the Lennard-Jones (LJ) fluid. Our work generalizes to soft potentials the original application of the method to hard sphere freezing, and builds on a previous PSMC study of the LJ system by Errington (J. Chem. Phys. {\bf 120}, 3130 (2004)). The latter work is extended by tracing

C. W. Chu, F. Chen, J. Shulman, S. Tsui

The significance of a negative dielectric constant has long been recognized. We report here the observation of a field-induced large negative dielectric constant of aggregates of oxide nano-particles at frequencies below ~ 1 Hz at room temperature. The accompanying induced charge detected opposes the electric field applied in the field-induced negative diele

A. Rosch

We briefly review some basic aspects of transport in clean metals focusing on the role of electron-electron interactions and neglecting the effects of impurities, phonons and interband transitions. Both for small Fermi surfaces of two and three-dimensional metals and open Fermi surfaces of quasi one-dimensional metals the dc conductivity sigma is largely dom

M. Centelles, M. Guilleumas, M. Barranco, R. Mayol

Using mean field theory, we have studied Bose-Fermi mixtures in a one-dimensional optical lattice in the case of an attractive boson-fermion interaction. We consider that the fermions are in the degenerate regime and that the laser intensities are such that quantum coherence across the condensate is ensured. We discuss the effect of the optical lattice on th

M. Guilleumas, M. Centelles, M. Barranco, R. Mayol

We investigate within mean-field theory the influence of a one-dimensional optical lattice and of trapped degenerate fermions on the critical rotational frequency for vortex line creation in a Bose-Einstein condensate. We consider laser intensities of the lattice such that quantum coherence across the condensate is ensured. We find a sizable decrease of the

Gao Xianlong, Marco Polini, Reza Asgari, M. P. Tosi

Two-component Fermi gases with tunable repulsive or attractive interactions inside quasi-one-dimensional (Q1D) harmonic wells may soon become the cleanest laboratory realizations of strongly correlated Luttiger and Luther-Emery liquids under confinement. We present a microscopic Kohn-Sham density-functional theory of these systems, with specific attention to

A. V. Rozhkov

We study the pancake lattice system induced by application of transverse magnetic filed to the layered superconductor. A simple statistical field theory for the pancake lattice is derived. It incorporates effects of the magnetic interaction between pancakes as well as those of the interlayer Josephson coupling. The proposed description enables us to estimate

P. -P. Cortet, L. Vanel, S. Ciliberto

Taking into account stress fluctuations due to thermal noise, we study thermally activated irreversible crack growth in disordered media. The influence of material disorder on sub-critical growth of a single crack in two-dimensional brittle elastic material is described through the introduction of a rupture threshold distribution. We derive analytical predic

D. Budker, S. K. Lamoreaux, A. O. Sushkov, O. P. Sushkov

Experiments searching for parity- and time-reversal-invariance-violating effects that rely on measuring magnetization of a condensed-matter sample induced by application of an electric field are considered. A limit on statistical sensitivity arises due to random fluctuations of the spins in the sample. The scaling of this limit with the number of spins and t

Hu Zhao, Shi-jie Yang, Shiping Feng

The giant vortex states of a multiply connected superconductor, with radius comparable to the penetration depth and the coherence length, are theoretically investigated based on the nonlinear Ginzburg-Landau theory, in which the induced magnetic field by the super-currents is accurately taken into account. The solutions of Ginzburg-Landau equations are found

Hideo Yoshioka

We investigate Knight shift and nuclear spin relaxation rate in a charge ordered state of the one-dimensional extended Hubbard model with a quarter filled band by using RPA around the mean-field solution. It is shown that both quantities show splitting below the critical temperature of the charge order, as is experimentally observed. The relationship between

Timo Hyart, Kirill N. Alekseev, Ahti Leppanen, Erkki V. Thuneberg

We theoretically consider the amplification of THz radiation in a superlattice Bloch oscillator. The main dilemma in the realization of THz Bloch oscillator is finding operational conditions which allow simultaneously to achieve gain at THz frequencies and to avoid destructive space-charge instabilities. A possible solution to this dilemma is the extended Li

Barbaros Oezyilmaz, Andrew D. Kent

Current induced magnetization dynamics in asymmetric Cu/Co/Cu single magnetic layer nanopillars has been studied experimentally at room temperature and in low magnetic fields applied perpendicular to the thin film plane. In sub-100 nm junctions produced using a nanostencil process a bistable state with two distinct resistance values is observed. Current swee

Yoshihiro Watanabe, Nobuko Fuchikami

We performed molecular dynamics simulations on a one-dimensional diatomic gas to investigate the possible long time scale inherent in heterogeneous Hamiltonian systems. The exponentially long time scale for energy sharing between the translational motion and the vibrational one certainly exists in a large limit of the system size. The time scale depends on t