June 2006 arXiv papers — page 25

L. R. Spitler, S. S. Larsen, J. Strader, J. P. Brodie

A detailed imaging analysis of the globular cluster (GC) system of the Sombrero galaxy (NGC 4594) has been accomplished using a six-image mosaic from the Hubble Space Telescope Advanced Camera for Surveys. The quality of the data is such that contamination by foreground stars and background galaxies is negligible for all but the faintest 5% of the GC luminos

Mark Dijkstra, Stuart Wyithe

Recent surveys have detected Lya emission from z=4.5-6.5 at luminosities as low as 10^41 erg/s. There is good evidence that low numbers of AGN are among observed faint Lya emitters. Combining these observations with an empirical relation between the intrinsic Lya and B-band luminosities of AGN, we obtain an upper limit on the number density of AGN with absol

Hideo Itoh, Nobuchika Okada, Toshifumi Yamashita

We propose a scenario of gravity mediated supersymmetry breaking (gravity mediation) in a supersymmetric Randall-Sundrum model. In our setup, both of the visible sector and the hidden sector co-exist on the infrared (IR) brane. We introduce the Polonyi model as a simple hidden sector. Due to the warped metric, the effective cutoff scale on the IR brane is ``

U. Chatterjee, D. K. Morr, M. R. Norman, M. Randeria

We introduce a formalism for calculating dynamic response functions using experimental single particle Green's functions derived from angle resolved photoemission spectroscopy (ARPES). As an illustration of this procedure we estimate the dynamic spin response of the cuprate superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$. We find good agreement with superco

S. Glancy, E. Knill, H. M. Vasconcelos

We present a method for multipartite entanglement purification of any stabilizer state shared by several parties. In our protocol each party measures the stabilizer operators of a quantum error-correcting code on his or her qubits. The parties exchange their measurement results, detect or correct errors, and decode the desired purified state. We give suffici

Daniel Sepunaru

We discuss an alternative version of non- relativistic Newtonian mechanics in terms of a real Hilbert space mathematical framework. It is demonstrated that the physics of this scheme correspondent with the standard formulation. Heisenberg-Schrodinger non-relativistic quantum mechanics is considered adequate and complete. Since the suggested theory is dispers

Francesco Buscemi, Giacomo Mauro D'Ariano, Chiara Macchiavello

We describe a unified framework of phase covariant multi user quantum transformations for d-dimensional quantum systems. We derive the optimal phase covariant cloning and transposition tranformations for multi phase states. We show that for some particular relations between the input and output number of copies they correspond to economical tranformations, w

B. H. Liu, F. W. Sun, Y. X. Gong, Y. F. Huang

Multi-photon interference is at the heart of the recently proposed linear optical quantum computing scheme and plays an essential role in many protocols in quantum information. Indistinguishability is what leads to the effect of quantum interference. Optical interferometers such as Michaelson interferometer provide a measure for second-order coherence at one

Xin Li, Tian Liu, Han Peng, Hongtao Sun

This paper discusses properties of quantum fingerprinting with shared entanglement. Under certain restriction of final measurement, a relation is given between unitary operations of two parties. Then, by reducing to spherical coding problem, this paper gives a lower bound of worst case error probability for quantum fingerprinting with shared entanglement, sh

Wentian Li, Young Ju Suh, Jingshan Zhang

A common practice in microarray analysis is to transform the microarray raw data (light intensity) by a logarithmic transformation, and the justification for this transformation is to make the distribution more symmetric and Gaussian-like. Since this transformation is not universally practiced in all microarray analysis, we examined whether the discrepancy o

Wen Fury, Franak Batliwalla, Peter K. Gregersen, Wentian Li

When the same set of genes appear in two top ranking gene lists in two different studies, it is often of interest to estimate the probability for this being a chance event. This overlapping probability is well known to follow the hypergeometric distribution. Usually, the lengths of top-ranking gene lists are assumed to be fixed, by using a pre-set criterion

Wentian Li, Pedro Miramontes

Human chromosome 21 is the only chromosome in human genome that exhibits oscillation of (G+C)-content of cycle length of hundreds kilobases (500 kb near the right telomere). We aim at establishing the existence of similar periodicity in structure-related sequence features in order to relate this (G+C)% oscillation to other biological phenomena. The following

Hong Qian, Daniel A. Beard

It has long been hypothesized that futile cycles in cellular metabolism are involved in the regulation of biochemical pathways. Following the work of Newsholme and Crabtree, we develop a quantitative theory for this idea based on open-system thermodynamics and metabolic control analysis. It is shown that the {\it stoichiometric sensitivity} of an intermediar

Anatoli Andrei Vankov

Controversies arise when specialists disagree on some particular issue. This normally occurs in any scientific brunch. We analyze some controversies, which have a good cause in Special Relativity. The paper does not question Special Relativity Theory but it challenges changing deeply held academic beliefs about imaginary experiments in Special Relativity The

Uday K. Chettiar, Alexander V. Kildishev, Thomas A. Klar, Vladimir M. Shalaev

We present simulation results of a design for negative index materials that uses magnetic resonators to provide negative permeability and metal film for negative permittivity. We also discuss the possibility of using semicontinuous metal films to achieve better manufacturability and enhanced impedance matching.

Motomichi Tashiro, Keiji Morokuma, Jonathan Tennyson

Differential cross sections for electron collisions with the O$_2$ molecule in its ground ${X}^{3}Σ_g^-$ state, as well as excited ${a}^{1}Δ_g$ and ${b}^{1}Σ_g^+$ states are calculated. As previously, the fixed-bond R-matrix method based on state-averaged complete active space SCF orbitals is employed. In additions to elastic scattering of electron with the

Carlos Escudero

To date it has not been possible to prove whether or not the three-dimensional incompressible Euler equations develop singular behaviour in finite time. Some possible singular scenarios, as for instance shock-waves, are very important from a physical point of view, since they imply the connection among the macroscopic and the microscopic scale. Therefore, th

A. Bertoldi, G. Lamporesi, L. Cacciapuoti, M. de Angelis

We developed a gravity-gradiometer based on atom interferometry for the determination of the Newtonian gravitational constant \textit{G}. The apparatus, combining a Rb fountain, Raman interferometry and a juggling scheme for fast launch of two atomic clouds, was specifically designed to reduce possible systematic effects. We present instrument performances a

J. Priede, G. Gerbeth

This paper presents a theoretical study of oscillatory and rotational instabilities of a solid spherical body, levitated electromagnetically in axisymmetric coils made of coaxial circular loops. We apply our previous theory to analyze the static and dynamic stability of the sample depending on the ac frequency and the position of the sample in the coils for

Vincent Luboz, Dominique Ambard, Pascal Swider, Franck Boutault

BACKGROUND: Proptosis is characterized by a protrusion of the eyeball due to an increase of the orbital tissue volume. To recover a normal eyeball positioning, the most frequent surgical technique consists in the osteotomy of orbital walls combined with the manual loading on the eyeball. Only a rough clinical rule is currently available for the surgeons but

J. Priede, I. Grants, G. Gerbeth

We consider the magnetorotational instability (MRI) of a hydrodynamically stable Taylor-Couette flow with a helical external magnetic field in the inductionless approximation defined by a zero magnetic Prandtl number ($\Pm=0)$. This leads to a considerable simplification of the problem eventually containing only hydrodynamic variables. First, we point out th

Stefan Duhr, Dieter Braun

Thermophoresis moves molecules along temperature gradients, typically from hot to cold. We superpose fluid flow with thermophoretic molecule flow under well defined microfluidic conditions, imaged by fluorescence microscopy. DNA is trapped and accumulated 16-fold in regions where both flows move in opposite directions. Strong 800-fold accumulation is expecte

Marine Laroche, Raquel Gomez-Medina, Juan Jose Saenz

The absorption and extinction spectra of sub-wavelength cylinder arrays are shown to present two different kind of resonances. Close to the Rayleigh anomalies, the diffractive coupling with the lattice periodicity leads to sharp peaks in the extinction spectra with characteristic Fano line shapes for both s and p-polarizations. When the material exhibits an

G. Y. Liang, G. Zhao, J. L. Zeng, J. R. Shi

Theoretical electron density-sensitive line ratios $R_1 - R_6$ of Ar XIV soft X-ray emission lines are presented. We found that these line ratios are sensitive to electron density $n_e$, and the ratio $R_1$ is insensitive to electron temperature $T_e$. Recent work has shown that accurate atomic data, such as electron impact excitation rates, is very importan

V. Gontis, B. Kaulakys

Earlier we proposed the stochastic point process model, which reproduces a variety of self-affine time series exhibiting power spectral density S(f) scaling as power of the frequency f and derived a stochastic differential equation with the same long range memory properties. Here we present a stochastic differential equation as a dynamical model of the obser

T. P. Gorringe

We report results from shell model studies of muon capture on $^{40}$Ca to low-lying levels of $^{40}$K. We discuss the comparison between calculated capture rates, measured capture rates and analogous transitions in ($e$,$e^{\prime}$) scattering in terms of the particle-hole structure of the $^{40}$Ca-$^{40}$K nuclei. We highlight the $^{40}$Ca$(0^+, 0)$$\t

R. Skibinski, J. Golak, H. Witala, W. Gloeckle

Present day chiral nucleon-nucleon potentials up to N3LO and three nucleon forces at N2LO are used to analyze nucleon-deuteron radiative capture at deuteron lab energies below E_d= 100 MeV. The differential cross section and the deuteron analyzing powers A_y(d) and A_{yy} are presented and compared to data. The theoretical predictions are obtained in the mom

M. Agnello, G. Beer, L. Benussi, M. Bertani

Momenta spectra of protons emitted following the capture of $K^-$ in $^6$Li and $^{12}$C have been measured with 1% resolution. The $^{12}$C spectrum is smooth whereas for $^6$Li a well defined peak appears at about 500 MeV/$c$. The first observation of a structure in this region was identified as a strange tribaryon or, possibly, a $\bar K$-nuclear state. T

Jovan Milosevic

Elliptic flow measurements as a function of p_T of charged (pi^+- and low-p_T protons) and strange (Lambda and K^0_S) particles from Pb+Au collisions at 158 AGeV/c are presented, together with measurements of phi and K^0_S meson production. A mass ordering effect was observed. Scaling to the number of constituent quarks and transverse rapidity y^fs_T scaling

J. Bec, M. Cencini, R. Hillerbrand

A statistical description of heavy particles suspended in incompressible rough self-similar flows is developed. It is shown that, differently from smooth flows, particles do not form fractal clusters. They rather distribute inhomogeneously with a statistics that only depends on a local Stokes number, given by the ratio between the particles' response tim

B. Dietz. T. Guhr, H. L. Harney, A. Richter

Flat microwave cavities can be used to experimentally simulate quantum mechanical systems. By coupling two such cavities, we study the equivalent to the symmetry breaking in quantum mechanics. As the coupling is tunable, we can measure resonance strength distributions as a function of the symmetry breaking. We analyze the data employing a qualitative model b

Montserrat Teixidor i Bigas

A coherent system of type (r,d,k) on a curve C is a pair (E,V) where E is a vector bundle of rank r and degree d and V is a space of sections of E of dimension k. There is a condition of stability on coherent systems that depends on a parameter αand allows to construct moduli spaces for such pairs. This paper shows non-emptiness of these moduli spaces when k

Claudio Gorodski

This is a short, elementary survey article about taut submanifolds. In order to simplify the exposition, we restrict to the case of compact smooth submanifolds of Euclidean or spherical spaces. Some new, partial results concerning taut 4-manifolds are discussed at the end of the text.

Youngjean Jung, Kevin T. Chu, Salvatore Torquato

In this paper, we study triply periodic surfaces with minimal surface area under a constraint in the volume fraction of the regions (phases) that the surface separates. Using a variational level set method formulation, we present a theoretical characterization of and a numerical algorithm for computing these surfaces. We use our theoretical and computational

Giorgio Fabbri, Silvia Faggian, Fausto Gozzi

In this paper we consider a family of optimal control problems for economic models whose state variables are driven by Delay Differential Equations (DDE's). We consider two main examples: an AK model with vintage capital and an advertising model with delay effect. These problems are very difficult to treat for three main reasons: the presence of the DDE&

Christian Pierre

A rather complete phenomenology of the singularities is developed according to a new algebraic point of view in the frame of Langlands global correspondences. That is to say,a process of: -singularizations and versal deformations of these, -singularizations and monodromies of these, is envisaged on all the sections of sheaves of differentiable (bi)functions

Atabey Kaygun, Masoud Khalkhali

For module algebras and module coalgebras over an arbitrary bialgebra, we define two types of bivariant cyclic cohomology groups called bivariant Hopf cyclic cohomology and bivariant equivariant cyclic cohomology. These groups are defined through an extension of Connes' cyclic category $Λ$. We show that, in the case of module coalgebras, bivariant Hopf c

V. Tkachenko

We prove an explicit formula for the spectral expansions in $L^2(\R)$ generated by selfadjoint differential operators $$ (-1)^n\frac{d^{2n}}{dx^{2n}}+\sum\limits_{j=0}^{n-1}\frac{d^{j}}{dx^{j}} p_j(x)\frac{d^{j}}{dx^{j}},\quad p_j(x+π)=p_j(x),\quad x\in\R. $$

Jean-François Marckert

We consider branching random walks built on Galton-Watson trees with offspring distribution having a bounded support, conditioned to have $n$ nodes, and their rescaled convergences to the Brownian snake. We exhibit a notion of "globally centered discrete snake'' that extends the usual settings in which the displacements are supposed centered. We

Riccardo Pulcini

We study some elementary properties of the quantum enveloping algebra associated to a parabolic subalgebra $\mathfrak{p}$ of a semisimple Lie algebra $\mathfrak{g}$. In particular we prove an explicit formula for the degree of this algebra, that extends the well known formula for the quantum enveloping algebra associated to $\mathfrak{g}$ and $\mathfrak{b}$,

H. R. Morton

Given an invariant J(K) of a knot K, the corresponding (1,1)-tangle invariant J'(K)=J(K)/J(U) is defined as the quotient of J(K) by its value J(U) on the unknot U. We prove here that J' is always an integer 2-variable Laurent polynomial when J is the Homfly satellite invariant determined by decorating K with any eigenvector of the meridian map in the

S. Nikolenko, N. Semenov

We show how to translate the task of computing the multiplicative structure of a Chow ring of a projective homogeneous variety into an easily understandable combinatorial task of calculating in the corresponding polynomial ring. The algorithms are also presented as a Maple package. Then we proceed to compute the multiplicative structure of the Chow rings for

Walter Van Assche

Rakhmanov's theorem for orthogonal polynomials on the unit circle gives a sufficient condition on the orthogonality measure for orthogonal polynomials on the unit circle, in order that the reflection coefficients (the recurrence coefficients in the Szego recurrence relation) converge to zero. In this paper we give the analog for orthogonal matrix polynom

Bruno Angles, Tatiana Beliaeva

In this note, we investigate the p-adic behavior of Weil numbers in the cyclotomic $\mathbb Z\_p$-extension of $\mathbb Q(ζ\_p).$ We determlne the characteristic ideal of the quotient of semi-local units by Weil numbers in terms of the characteristic ideals of some classical modules that appear in Iwasawa Theory.

Aaron D. Lauda, Hendryk Pfeiffer

We use a special kind of 2-dimensional extended Topological Quantum Field Theories (TQFTs), so-called open-closed TQFTs, in order to extend Khovanov homology from links to arbitrary tangles, not necessarily even. For every plane diagram of an oriented tangle, we construct a chain complex whose homology is invariant under Reidemeister moves. The terms of this

Muriel Livernet, Frederic Patras

The present article takes advantage of the properties of algebras in the category of S-modules (twisted algebras) to investigate further the fine algebraic structure of Hopf operads. We prove that any Hopf operad P carries naturally the structure of twisted Hopf P-algebra. Many properties of classical Hopf algebraic structures are then shown to be encapsulat

Laurent Desvillettes, Clément Mouhot

We consider the spatially homogeneous Boltzmann equation for regularized soft potentials and Grad's angular cutoff. We prove that uniform (in time) bounds in $L^1 ((1 + |v|^s)dv)$ and $H^k$ norms, $s, k \ge 0$ hold for its solution. The proof is based on the mixture of estimates of polynomial growth in time of those norms together with the quantitative r

Daniel Beltita, Tudor S. Ratiu, Alice Barbara Tumpach

We investigate some basic questions concerning the relationship between the restricted Grassmannian and the theory of Banach Lie-Poisson spaces. By using universal central extensions of Lie algebras, we find that the restricted Grassmannian is symplectomorphic to symplectic leaves in certain Banach Lie-Poisson spaces, and the underlying Banach space can be c

Brent Everitt

A self-contained exposition is given of the topological and Galois-theoretic properties of the category of combinatorial 1-complexes, or graphs, very much in the spirit of Stallings. A number of classical, as well as some new results about free groups are derived.

Tongzhu Li, Changping Wang

Laguerre geometry of surfaces in $\R^3$ is given in the book of Blaschke [1], and have been studied by E.Musso and L.Nicolodi [5], [6], [7], B. Palmer [8] and other authors. In this paper we study Laguerre differential geometry of hypersurfaces in $\R^n$. For any umbilical free hypersurface $x: M\to\R^n$ with non-zero principal curvatures we define a Laguerr

Diego Dominici

We analyze the polynomials $H_{n}^{r}(x)$ considered by Gould and Hopper, which generalize the classical Hermite polynomials. We present the main properties of $H_{n}^{r}(x)$ and derive asymptotic approximations for large values of $n$ from their differential-difference equation, using a discrete ray method. We give numerical examples showing the accuracy of

Eric M. Rains

In recent work (math/0507514) by Etingof, Henriques, Kamnitzer, and the author, a presentation and explicit basis was given for the rational cohomology of the real locus $\bar{M_{0,n}}(\RR)$ of the moduli space of stable genus 0 curves with $n$ marked points. We determine the graded character of the action of $S_n$ on this space (induced by permutations of t

Sam Nelson, Chau-Yim Wong

We study the structure of finite quandles in terms of subquandles. Every finite quandle $Q$ decomposes in a natural way as a union of disjoint $Q$-complemented subquandles; this decomposition coincides with the usual orbit decomposition of $Q$. Conversely, the structure of a finite quandle with a given orbit decomposition is determined by its structure maps.

Anton M. Zeitlin

We continue the study of the quantization of supersymmetric integrable KdV hierarchies. We consider the N=2 KdV model based on the $sl^{(1)}(2|1)$ affine algebra but with a new algebraic construction for the L-operator, different from the standard Drinfeld-Sokolov reduction. We construct the quantum monodromy matrix satisfying a special version of the reflec

Yu Nakayama, Soo-Jong Rey, Yuji Sugawara

We propose a new worldsheet approach to the McGreevy-Silverstein proposal: resolution of spacelike singularity via Scherk-Schwarz compactification and winding string condensation therein. Our proposal is built upon so-called three parameter sine-Liouville theory, which has useful features and could be solvable in conformal field theory method. Utilizing stan

Federico Elmetti, Andrea Mauri, Silvia Penati, Alberto Santambrogio

We study the \cal{N}=1 SU(N) SYM theory which is a marginal deformation of the \cal{N}=4 theory, with a complex deformation parameter \beta. We consider the large N limit and study perturbatively the conformal invariance condition. We find that finiteness requires reality of the deformation parameter \beta.

James Gray, Yang-Hui He, André Lukas

We develop a new and efficient method to systematically analyse four dimensional effective supergravities which descend from flux compactifications. The issue of finding vacua of such systems, both supersymmetric and non-supersymmetric, is mapped into a problem in computational algebraic geometry. Using recent developments in computer algebra, the problem ca

S. Cnockaert

In this thesis, we present two aspects of higher-spin gauge field theories: dualities and interactions. We first consider dualities of the free theories at the level of the action. Then, external "electric" and "magnetic" sources are introduced a la Dirac, which leads to a quantization condition on the product of conserved "electric"

Marek Rogatko

The uniqueness theorem for static charged higher dimensional black hole containing an asymptotically flat spacelike hypersurface with compact interior and with both degenerate and non-degenerate components of event horizon is proposed. By studies of the near-horizon geometry of degenerate horizons one was able to eliminate the previous restriction concerning

Eduard Masso, Javier Redondo

We comment on the recent experimental results from the PVLAS and CAST collaborations that search for axion-like particles. We propose a particle physics model in which their apparent inconsistency is circumvented.

A R. Haghpayma

In a conventional covark model we constructed the Theta pentaquark wave function using vector diquarks and calculating the mass spectrum of this exotic pentaquark.

T. Kodama, T. Koide, G. S. Denicol, Ph. Mota

We discuss some open problems in hydrodynamical approach to the relativistic heavy ion collisions. In particular, we propose a new, very simple alternative approach to the relativistic dissipative hydrodynamics of Israel and Stewart.

M. Breskvar, D. Lukman, N. S. Mankoc Borstnik

The approach unifying all the internal degrees of freedom - proposed by one of us - is offering a new way of understanding families of quarks and leptons. Spinors, namely, living in d(=1+13)-dimensional space, manifest in the observed d(=1+3) space all the known charges of quarks and leptons, while a part of the starting Lagrange density in d(=1+13) transfor

Mark Alford, Krishna Rajagopal

At ultra-high density, matter is expected to form a degenerate Fermi gas of quarks in which there is a condensate of Cooper pairs of quarks near the Fermi surface: color superconductivity. In this chapter we review some of the underlying physics, and discuss outstanding questions about the phase structure of ultra-dense quark matter. We then focus on describ

K. Langfeld, M. Quandt, W. Lutz, H. Reinhardt

The frustrated Ising model in two dimensions is revisited. The frustration is quantified in terms of the number of non-trivial plaquettes which is invariant under the Nishimori gauge symmetry. The exact ground state energy is calculated using Edmond's algorithm. A novel cluster algorithm is designed which treats gauge equivalent spin glasses on equal foo

NA49 Collaboration, C. Alt

The production of charged pions in minimum bias p+C interactions is studied using a sample of 377000 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.8 GeV/c in transverse momentum and from -0.1 to 0.5 in Feynman x. Inclusive invariant cross sections are given o

Andrzej Trautman

The Einstein--Cartan Theory (ECT) of gravity is a modification of General Relativity Theory (GRT), allowing space-time to have torsion, in addition to curvature, and relating torsion to the density of intrinsic angular momentum. This modification was put forward in 1922 by Elie Cartan, before the discovery of spin. Cartan was influenced by the work of the Co

Shane Legg

Solomonoff's inductive learning model is a powerful, universal and highly elegant theory of sequence prediction. Its critical flaw is that it is incomputable and thus cannot be used in practice. It is sometimes suggested that it may still be useful to help guide the development of very general and powerful theories of prediction which are computable. In

Loïs Rigouste, Olivier Cappé, François Yvon

In this article, we investigate the use of a probabilistic model for unsupervised clustering in text collections. Unsupervised clustering has become a basic module for many intelligent text processing applications, such as information retrieval, text classification or information extraction. The model considered in this contribution consists of a mixture of

Christian Hett, Nicolai Kuntze, Andreas U. Schmidt

We present a concept to achieve non-repudiation for natural language conversations by electronically signing packet-based, digital, voice communication. Signing a VoIP-based conversation means to protect the integrity and authenticity of the bidirectional data stream and its temporal sequence which together establish the security context of the communication

Audun Josang

The problem of combining beliefs in the Dempster-Shafer belief theory has attracted considerable attention over the last two decades. The classical Dempster's Rule has often been criticised, and many alternative rules for belief combination have been proposed in the literature. The consensus operator for combining beliefs has nice properties and produces

Xin Li, Tian Liu, Han Peng, Hongtao Sun

M.Alekhnovich et al. recently have proposed a model of algorithms, called BT model, which covers Greedy, Backtrack and Simple Dynamic Programming methods and can be further divided into fixed, adaptive and fully adaptive three kinds, and have proved exponential time lower bounds of exact and approximation algorithms under adaptive BT model for Knapsack probl

Adam Slagell, Kiran Lakkaraju, Katherine Luo

FLAIM (Framework for Log Anonymization and Information Management) addresses two important needs not well addressed by current log anonymizers. First, it is extremely modular and not tied to the specific log being anonymized. Second, it supports multi-level anonymization, allowing system administrators to make fine-grained trade-offs between information loss

James A. R. Marshall

The 2 x 2 games, in particular the Prisoner's Dilemma, have been extensively used in studies into reciprocal cooperation and, to a lesser extent, kin selection. This paper examines the suitability of the 2 x 2 games for modelling the evolution of cooperation through reciprocation and kin selection. This examination is not restricted to the Prisoner's

P. M. Pasinetti, F. Roma, J. L. Riccardo, A. J. Ramirez-Pastor

Monte Carlo (MC) simulations and finite-size scaling analysis have been carried out to study the critical behavior in a submonolayer two-dimensional gas of repulsive linear $k$-mers on a triangular lattice at coverage $k/(2k+1)$. A low-temperature ordered phase, characterized by a repetition of alternating files of adsorbed $k$-mers separated by $k+1$ adjace

A. Vorontsov, I. Vekhter

Diamagnetically coupled magnetic field can be used as a probe of nodal positions in unconventional superconductors. The heat capacity depends on the angle $ϕ_0$ between the magnetic field and the nodal directions. We show that the anisotropy $C(ϕ_0)$ persists even in systems with strong paramagnetic coupling to the electrons's spins.

G. Schwiete, K. B. Efetov

Spin susceptibility of a clean Fermi gas with repulsion in any dimension is considered using a supersymmetric low energy theory of interacting spin excitations and renormalization scheme recently proposed by Aleiner and Efetov [cond-mat/0602309]. We generalize this method to include the coupling to the magnetic field. As a result, we obtain for the correctio

Badrinarayan P. Athreya, Jonathan A. Dantzig, Shan Liu, Rohit Trivedi

We use a phase-field model to study the effect of confinement on dendritic growth, in a pure material solidifying in an undercooled melt, and in the directional solidification of a dilute binary alloy. Specifically, we observe the effect of varying the vertical domain extent ($δ$) on tip selection, by quantifying the dendrite tip velocity and curvature as a

Piet W. Brouwer, Saar Rahav

The scattering matrix S of a ballistic chaotic cavity is the direct sum of a `classical' and a `quantum' part, which describe the scattering of channels with typical dwell time smaller and larger than the Ehrenfest time, respectively. According to the `effective random matrix theory' of Silvestrov, Goorden, and Beenakker [Phys. Rev. Lett. 90, 116

Alec Maassen van den Brink

We study the complex-valued resonance spectrum of a dc-SQUID coupled to a flux qubit, where the former is treated in the cubic and the latter in the two-level approximation. It is shown that this spectrum is well-defined and contains most of the relevant information on the escape process. Thus, the language of resonance states is precise and well-adapted to

Guanghui Zhou, Wenhu Liao

We investigate theoretically the electronic structure and transport for a two-level quantum wire with Rashba spin-orbit coupling (SOC) under the irradiation of an external laser field at low temperatures. The photon-induced transitions between SOC-splitted subbands with the same lateral confinement quantum numbers and between subbands with different confinem

David Hochberg, M. -P. Zorzano, Federico Moran

We derive exact Langevin-type equations governing quasispecies dynamics. The inherent multiplicative noise has both real and imaginary parts. The numerical simulation of the underlying complex stochastic partial differential equations is carried out employing the Cholesky decomposition for the noise covariance matrix. This noise produces unavoidable spatio-t

S. Reich, G. Leitus, Y. Feldman

Direct magnetization measurements of thin gold films are presented. These measurements integrate the signal from the thin film under study and the magnetic contribution of the film's interface with the substrate. The diamagnetic contribution to the signal from the bulk substrate is of the same order as the noise level. we find that thin gold films can ex

R. Stadler, K. W. Jacobsen

The alignment of the Fermi level of a metal electrode within the gap of the hi ghest occupied (HOMO) and lowest unoccupied orbital (LUMO) of a molecule is a key quantity in molecular electronics, which can vary the electron transparency of a single molecule junction by orders of magnitude. We present a quantitative analysis of the relation between this level

Matteo Calandra, Francesco Mauri

Using density functional theory we investigate the occurrence of superconductivity in AC$_6$ with A=Mg,Ca,Sr,Ba. We predict that at zero pressure, Ba and Sr should be superconducting with critical temperatures (T$_c$) 0.2 K and 3.0 K, respectively. We study the pressure dependence of T$_c$ assuming the same symmetry for the crystal structures at zero and fin

Wouter Kager, Bernard Nienhuis

We study a special case of the Brauer model in which every path of the model has weight q=1. The model has been studied before as a solvable lattice model and can be viewed as a Lorentz lattice gas. The paths of the model are also called self-avoiding trails. We consider the model in a triangle with boundary conditions such that one of the trails must cross

Yoji Ohashi

Effects of superconducting fluctuations on the Fulde-Ferrell (FF) state are discussed in a spatially isotropic three-dimensional superconductor under a magnetic field. For this system, Shimahara recently showed that within the phenomenological Ginzburg-Landau theory, the long-range order of the FF state is suppressed by the phase fluctuation of the supercond

R. Burioni, D. Cassi, F. Corberi, A. Vezzani

We study phase ordering on networks and we establish a relation between the exponent $a_χ$ of the aging part of the integrated autoresponse function $χ_{ag}$ and the topology of the underlying structures. We show that $a_χ>0$ in full generality on networks which are above the lower critical dimension $d_L$, i.e. where the corresponding statistical model has

D. Volchenkov, R. Lima

The Brownian motion over the space of fluid velocity configurations driven by the hydrodynamical equations is considered. The Green function is computed in the form of an asymptotic series close to the standard diffusion kernel. The high order asymptotic coefficients are studied. Similarly to the models of quantum field theory, the asymptotic contributions d

V. I. Yukalov

The necessity of accurately taking into account the existence of nonequivalent operator representations, associated with canonical transformations, is discussed. It is demonstrated that Bose systems in the presence of the Bose-Einstein condensate and without it correspond to different Fock spaces, orthogonal to each other. A composite representation for the

J. M. Rubi, D. Bedeaux, S. Kjelstrup

We show how to construct non-equilibrium thermodynamics for systems too small to be considered thermodynamically in a traditional sense. Through the use of a non-equilibrium ensemble of many replicas of the system which can be viewed as a large thermodynamic system, we discuss the validity of non-equilibrium thermodynamics relations and analyze the nature of

Georg Hager, Alexander Weisse, Gerhard Wellein, Eric Jeckelmann

We extend previous analytical studies of the ground-state phase diagram of a one-dimensional Heisenberg spin chain coupled to optical phonons, which for increasing spin-lattice coupling undergoes a quantum phase transition from a gap-less to a gaped phase with finite lattice dimerisation. We check the analytical results against established four-block and new

Wang-Kong Tse, P. T. Leung

Based on the model proposed by Hilgenfeldt {\it at al.} [Nature {\bf 398}, 401 (1999)], we present here a comprehensive theory of thermal radiation in single-bubble sonoluminescence (SBSL). We first invoke the generalized Kirchhoff's law to obtain the thermal emissivity from the absorption cross-section of a multilayered sphere (MLS). A sonoluminescing b

Peter Graf, Reimar Finken, Udo Seifert

The adhesion of microcapsules to an attractive contact potential is studied theoretically. The axisymmetric shape equations are solved numerically. Beyond a universal threshold strength of the potential, the contact radius increases like a square root of the strength. Scaling functions for the corresponding amplitudes are derived as a function of the elastic

K. Ebata, H. Wadati, M. Takizawa, A. Fujimori

We have studied the chemical potential shift and changes in the electronic density of states near the Fermi level ($E_F$) as a function of carrier concentration in Pr$_{1-x}$Ca$_x$MnO$_3$ (PCMO, $0.2 \le x \le 0.65$) through the measurements of photoemission spectra. The results showed that the chemical potential shift was suppressed for $x \agt 0.3$, where

G. E. Tsydynzhapov, A. F. Shevchun, M. R. Trunin, V. N. Zverev

A study of temperature dependences of the upper critical field B_{c2}(T) and surface impedance Z(T)=R(T)+iX(T) in Ba_{1-x}K_xBiO_3 single crystals that have transition temperatures in the range 6 < T_c < 32 K (roughly 0.6>x>0.4) reveals a transition from BCS to unusual type of superconductivity. B_{c2}(T) curves corresponding to the crystals that have T_c>20

Changgan Zeng, Yugui Yao, Qian Niu, Hanno H. Weitering

The anomalous Hall effect is investigated experimentally and theoretically for ferromagnetic thin films of Mn$_5$Ge$_3$. We have separated the intrinsic and extrinsic contributions to the experimental anomalous Hall effect, and calculated the intrinsic anomalous Hall conductivity from the Berry curvature of the Bloch states using first-principles methods. Th

M. Köppl, P. Henseler, A. Erbe, P. Nielaba

The transport behavior of a system of gravitationally driven colloidal particles is investigated. The particle interactions are determined by the superparamagnetic behavior of the particles. They can thus be arranged in a crystalline order by application of an external magnetic field. Therefore the motion of the particles through a narrow channel occurs in w

O. Bleibaum

We reexamine the boundary conditions of spin diffusion equations for dirty semiconductor heterostructures with weak linear Rashba spin-orbit interaction. Doing so, we focus on the influence of tangent derivatives of the particle density at the boundary on the magnetization. Such derivatives are associated with a spin accumulation in the presence of a density

Yuichi Nakamura, Naomichi Hatano

We study a non-Hermitian generalization of quantum systems in which an imaginary vector potential is added to the momentum operator. In the tight-binding approximation, we make the hopping energy asymmetric in the Hermitian Hamiltonian. In a previous article, we conjectured that the non-Hermitian critical point where the energy gap vanishes is equal to the i