January 2006 arXiv papers — page 22

Philippe Blanchard, Christophe Dobrovolny, Daniel Gandolfo, Jean Ruiz

The behaviour of the mean Euler-Poincaré characteristic and mean Betti's numbers in the Ising model with arbitrary spin on $\mathbbm{Z}^2$ as functions of the temperature is investigated through intensive Monte Carlo simulations. We also consider these quantities for each color $a$ in the state space $S\_Q = \{- Q, - Q + 2, ..., Q \}$ of the model. We fi

Taisei Kaizoji

In this paper we present an interacting-agent model of stock markets. We describe a stock market through an Ising-like model in order to formulate the tendency of traders getting to be influenced by the other traders' investment attitudes [1], and formulate the traders' decision-making regarding investment as the maximum entropy principle for nonexte

D. I. Golosov, Yuval Gefen

Measurements of the transmission phase in transport through a quantum dot embedded in an Aharonov-Bohm interferometer show systematic sequences of phase lapses separated by Coulomb peaks. Using a two-level quantum dot as an example we show that this phenomenon can be accounted for by the combined effect of asymmetric dot-lead coupling and interaction-induced

Jaewoo Joo, Yuan Liang Lim, Almut Beige, Peter L. Knight

Optical lattices with one atom on each site and interacting via cold controlled collisions provide an efficient way to entangle a large number of qubits with high fidelity. It has already been demonstrated experimentally that this approach is especially suited for the generation of cluster states [O. Mandel et al., Nature 425, 937 (2003)] which reduce the re

Takashi Hiramatsu

We discuss the cosmological evolution of the inflationary gravitational wave background (IGWB) in the Randall-Sundrum single-brane model. In the braneworld cosmology, in which three-dimensional space-like hypersurface that we live in is embedded in five-dimensional anti de Sitter (AdS_5) space-time, the evolution of gravitational wave (GW) modes is affected

Tim Edwards

We give a detailed proof that, for any natural number n, each algebraic two complex over C_n \times C_\infty is realised up to congruence by a geometric complex arising from a presentation for the group.

Tatsuyuki Takatsuka, Shigeru Nishizaki, Yasuo Yamamoto, Ryozo Tamagaki

Superfluidity of $Λ$ and $Σ^-$ admixed in neutron star (NS) cores is investigated realistically for hyperon ($Y$)-mixed NS models obtained using a $G$-matrix-based effective interaction approach. Numerical results for the equation of state (EOS) with the mixing ratios of the respective components and the hyperon energy gaps including the temperature dependen

Viatcheslav I. Kuvshinov, Andrei V. Kuzmin

We study decoherence induced by stochastic squeezing control errors considering the particular implementation of Hadamard gate on optical and ion trap holonomic quantum computers. We find the fidelity for Hadamard gate and compute the purity of the final state when the control noise is modeled by Ornstein-Uhlenbeck stochastic process. We demonstrate that in

Akiko Ueda, Mikio Eto

We theoretically study the resonant tunneling and Fano resonance in quantum dots with electron-phonon (e-ph) interaction. We examine the bias-voltage ($V$) dependence of the decoherence, using Keldysh Green function method and perturbation with respect to the e-ph interaction. With optical phonons of energy $ω_0$, only the elastic process takes place when $e

Rong-Gen Cai, Li-Ming Cao

Based on the recent paper hep-th/0503045, we derive a formula of calculating conserved charges in even dimensional asymptotically {\it locally} anti-de Sitter space-times by using the definition of Wald and Zoupas. This formula generalizes the one proposed by Ashtekar {\it et al}. Using the new formula we compute the masses of Taub-Bolt-AdS space-times by tr

Feng-Kun Guo, Peng-Nian Shen, Huan-Ching Chiang, Rong-Gang Ping

We perform a model-independent analysis for recently reported data of the $π^+π^-$ invariant mass spectra in the $Υ(4S)\toΥ(1S,2S)π^+π^-$ decays and point out that there does exist a broad peak below 0.6 GeV in the data of the $Υ(4S)\toΥ(1S)π^+π^-$ decay, which is analogous to that in the $Υ(3S)\toΥ(1S)π^+π^-$ decay. With the data of $Υ(4S)$ decays, we furth

J. S. Bagla, Jayanti Prasad

N-Body simulations are a very important tool in the study of formation of large scale structures. Much of the progress in understanding the physics of galaxy formation and comparison with observations would not have been possible without N-Body simulations. Given the importance of this tool, it is essential to understand its limitations as ignoring these can

Yasuya Nakayama, Kang Kim, Ryoichi Yamamoto

Previously, we have proposed a direct simulation scheme for colloidal dispersions in a Newtonian solvent [Phys.Rev.E 71,036707 (2005)]. An improved formulation called the ``Smoothed Profile (SP) method'' is presented here in which simultaneous time-marching is used for the host fluid and colloids. The SP method is a direct numerical simulation of par

Lorenza Viola

The problem of open-loop dynamical control of generic open quantum systems is addressed. In particular, I focus on the task of effectively switching off environmental couplings responsible for unwanted decoherence and dissipation effects. After revisiting the standard framework for dynamical decoupling via deterministic controls, I describe a different appro

Shubhrangshu Dasgupta, G. S. Agarwal

The first optical proposal for the realization of the two-bit version of the Deutsch-Jozsa algorithm [D. Deutsch and R. Jozsa, Proc. R. Soc. London A {\bf 493}, 553 (1992)] is presented. The proposal uses Stark shifts in an ensemble of atoms and degenerate sources of photons. The photons interact dispersively with an atomic ensemble, leading to an effective

G. Chiribella, G. M. D'Ariano, M. F. Sacchi

We present the optimal estimation of an unknown squeezing transformation of the radiation field. The optimal estimation is unbiased and is obtained by properly considering the degeneracy of the squeezing operator. For coherent input states, the r.m.s. of the estimation scales as $(2\sqrt {\bar n})^{-1}$ versus the average photon number $\bar n$, while it can

S. Castelletto, I. P. Degiovanni, V. Schettini, A. Migdall

We present a scheme for a photon-counting detection system that can be operated at incident photon rates higher than otherwise possible by suppressing the effects of detector deadtime. The method uses an array of N detectors and a 1-by-N optical switch with a control circuit to direct input light to live detectors. Our calculations and models highlight the a

J. -M. Sparenberg, B. F. Samsonov, F. Foucart, D. Baye

A new type of supersymmetric transformations of the coupled-channel radial Schroedinger equation is introduced, which do not conserve the vanishing behavior of solutions at the origin. Contrary to usual transformations, these ``non-conservative'' transformations allow, in the presence of thresholds, the construction of potentials with coupled scatter

Thomas Brougham, Erika Andersson, Stephen M. Barnett

A joint measurement of two observables is a {\it simultaneous} measurement of both quantities upon the {\it same} quantum system. When two quantum-mechanical observables do not commute, then a joint measurement of these observables cannot be accomplished by projective measurements alone. In this paper we shall discuss the use of quantum cloning to perform a

Johan Aberg

Interferometry of single particles with internal degrees of freedom is investigated. We discuss the interference patterns obtained when an internal state evolution device is inserted into one or both the paths of the interferometer. The interference pattern obtained is not uniquely determined by the completely positive maps (CPMs) that describe how the devic

Peter McHale, Wouter-Jan Rappel, Herbert Levine

Morphogens are proteins, often produced in a localised region, whose concentrations spatially demarcate regions of differing gene expression in developing embryos. The boundaries of expression must be set accurately and in proportion to the size of the one-dimensional developing field; this cannot be accomplished by a single gradient. Here, we show how a pai

C. F. Diether, A. E. Inopin

We present a unique geometrical model based on our findings of a quantum vacuum charge scenario to predict the recent experimental find of the new HyperCP 214 MeV particle state X. This model, which we call the Spin Matrix, also predicts many more states; some of which represent known particles and some states that aren't represented directly by known pa

J. Dawidowski, J. J. Blostein, J. R. Granada

Multiple scattering and attenuation corrections in Deep Inelastic Neutron Scattering experiments are analyzed. The theoretical basis is stated, and a Monte Carlo procedure to perform the calculation is presented. The results are compared with experimental data. The importance of the accuracy in the description of the experimental parameters is tested, and th

Basarab Nicolescu

After a short summary of the Sokal Affair and of the point of view of Steven Weinberg, we discuss certain aspects of the scientist ideology present in the last book of Alan Sokal "Pesudoscience ans Postmodernism: Antagonists or Fellow-Travellers?", published in France. The danger of the three extremisms present in our time - relativist extremism, sci

A. Greilich, M. Schwab, T. Berstermann, T. Auer

We compare the asymmetry-induced exchange splitting delta_1 of the bright-exciton ground-state doublet in self-assembled (In,Ga)As/GaAs quantum dots, determined by Faraday rotation, with its homogeneous linewidth gamma, obtained from the radiative decay in time-resolved photoluminescence. Post-growth thermal annealing of the dot structures leads to a conside

Yannick Ponty, Pablo Mininni, Jean-François Pinton, Hélène Politano

We compute numerically the threshold for dynamo action in Taylor-Green swirling flows. Kinematic calculations, for which the flow field is fixed to its time averaged profile, are compared to dynamical runs for which both the Navier-Stokes and the induction equations are jointly solved. The kinematic instability is found to have two branches, for all explored

Yuri A. Rylov

Two different strategies of the relativistic quantum theory construction are considered and evaluated. The first strategy is the conventional strategy, based on application of the quantum mechanics technique to relativistic systems. This approach cannot solve the problem of pair production. The apparent success of QFT at solution of this problem is condition

G. M. von Hippel

We present TaylUR, a Fortran 95 module to automatically compute the numerical values of a complex-valued function's derivatives w.r.t. several variables up to an arbitrary order in each variable, but excluding mixed derivatives. Arithmetic operators and Fortran intrinsics are overloaded to act correctly on objects of defined type "taylor", which

Rodolfo A. Diaz, William J. Herrera

Under certain conditions usually fulfilled in classical mechanics, the principle of conservation of linear momentum and Newton's third law are equivalent. However, the demonstration of this fact is usually incomplete in textbooks. We shall show here that to demonstrate the equivalence, we require the explicit use of the principle of superposition contain

P. Capel, F. M. Nunes

Calculations of the breakup of 8B and 11Be are performed with the aim of analyzing their sensitivity to the projectile description. Several potentials adjusted on the same experimental data are used for each projectile. The results vary significantly with the potential choice, and this sensitivity differs from one projectile to the other. In the 8B case, the

S. Pittel, N. Sandulescu

We describe the use of the Density Matrix Renormalization Group method as a means of approximately solving large-scale nuclear shell-model problems. We focus on an angular-momentum-conserving variant of the method and report test results for the nucleus $^{48}Cr$. The calculation is able to reproduce both the ground state energy and the energy of the first e

H. -J. Stoeckmann. H. Kohler

The concept of fidelity has been introduced to characterize the stability of a quantum-mechanical system against perturbations. The fidelity amplitude is defined as the overlap integral of a wave packet with itself after the development forth and back under the influence of two slightly different Hamiltonians. It was shown by Prosen and Znidaric in the linea

Christodoulos Sophocleous, Ron J. Wiltshire

We consider systems of diffusion equations that have considerable interest in Soil Science and Mathematical Biology and focus upon the problem of finding those forms of this class that can be linearized. In particular we use the equivalence transformations of the second generation potential system to derive forms of this system that can be linearized. In tur

Nikolai A. Kudryashov, Maria V. Demina

New method for finding exact solutions of nonlinear differential equations is presented. It is based on constructing the polygon corresponding to the equation studied. The algorithms of power geometry are used. The method is applied for finding one -- parameter exact solutions of the generalized Korteveg -- de Vries -- Burgers equation, the generalized Kuram

Yu. V. Brezhnev

For spectral problems, determined by ordinary differential equations, we consider finite-gap potentials as exact solvable by quadratures in the spirit of the Picard--Vessio theory and suggest that this class is the only one. Ideology goes back to works by Drach 1919 but has not been mentioned in the modern literature. We exhibit new examples and technique fo

Scott Crass

There is a family of seventh-degree polynomials $H$ whose members possess the symmetries of a simple group of order 168. This group has an elegant action on the complex projective plane. Developing some of the action's rich algebraic and geometric properties rewards us with a special map that also realizes the 168-fold symmetry. The map's dynamics pr

Steven Dale Cutkosky, Hema Srinivasan

We give a proof of local strong factorization of a birational extension of regular local rings (of equicharacteristic zero) along a valuation of rank 1 and maximal rational rank. This gives an alternate proof to the geometric proof of this Theorem by Karu. Our proof uses only linear algebra, and is in the spirit of Christensen's proof of this result in d

Nathael Gozlan

In this paper, we provide a characterization of a large class of transportation-cost inequalities in terms of exponential integrability of the cost function under the reference probability measure. Our results completely extend the previous works by Djellout, Guilin and Wu and Bolley and Villani.

S. M. Iacus, D. La Torre

Several methods are currently available to simulate paths of the Brownian motion. In particular, paths of the BM can be simulated using the properties of the increments of the process like in the Euler scheme, or as the limit of a random walk or via L2 decomposition like the Kac-Siegert/Karnounen-Loeve series. In this paper we first propose a IFSM (Iterated

Johannes F. Ebert, Roland M. Friedrich

In \cite{Boed}, C.-F. Bödigheimer constructed a finite cell-complex $\mf{Par}_{g,n,m}$ and a bijective map $\cH: \mf{Dip}_{g,n,m} \to \mf{Par}_{g,n,m}$ (the Hilbert-uniformization) from the moduli space of dipole functions on Riemann surfaces with $n$ directions and $m$ punctures to $\mf{Par}_{g,n,m}$. In \cite{Boed} and \cite{Eb}, it is proven that $\cH$ is

Alexander Postnikov, Bruce Sagan

Given a sequence of integers b = (b_0,b_1,b_2,...) one gives a Dyck path P of length 2n the weight wt(P) = b_{h_1} b_{h_2} ... b_{h_n}, where h_i is the height of the ith ascent of P. The corresponding weighted Catalan number is C_n^b = sum_P wt(P), where the sum is over all Dyck paths of length 2n. So, in particular, the ordinary Catalan numbers C_n corresp

Jean-Christophe Bourin

Several inequalities for eigenvalues involving convex combinations and compressions are given. These inequalities are matrix version of the basic convexity inequality f((a+b)/2) < (f(a)+f(b))/2.

Yehuda Pinchover

In this paper we prove a sufficient condition, in terms of the behavior of a ground state of a symmetric critical operator $P_1$, such that a nonzero subsolution of a symmetric nonnegative operator $P_0$ is a ground state. Particularly, if $P_j:=-Δ+V_j$, for $j=0,1$, are two nonnegative Schrödinger operators defined on $Ω\subseteq \mathbb{R}^d$ such that $P_

Yehuda Pinchover

The purpose of the paper is to review a variety of recent developments in the theory of positive solutions of general linear elliptic and parabolic equations of second-order on noncompact Riemannian manifolds, and to point out a number of their consequences.

Klaas Pieter Hart

We show there is no categorical metric continuum. This means that for every metric continuum X there is another metric continuum Y such that X and Y have (countable) elementarily equivalent bases but X and Y are not homeomorphic. As an application we show that the chainability of the pseudoarc is not a first-order property of its lattice of closed sets.

Sylvie Paycha, Simon Scott

For a holomorphic family of classical pseudodifferential operators on a closed manifold we give exact formulae for all coefficients in the Laurent expansion of its Kontsevich-Vishik canonical trace. This generalizes a known result identifying the Wodzicki residue with the pole at zero to all higher order terms.

Kiran S. Kedlaya

A p-typical cover of a connected scheme on which p=0 is a finite etale cover whose monodromy group (i.e., the Galois group of its normal closure) is a p-group. The geometry of such covers exhibits some unexpectedly pleasant behaviors; building on work of Katz, we demonstrate some of these. These include a criterion for when a morphism induces an isomorphism

Kevin J. Costello

This is the first of two papers which construct a purely algebraic counterpart to the theory of Gromov-Witten invariants (at all genera). These Gromov-Witten type invariants depend on a Calabi-Yau A-infinity category, which plays the role of the target in ordinary Gromov-Witten theory. When we use an appropriate A-infinity version of the derived category of

G. L. Cardoso, B. de Wit, J. Käppeli, T. Mohaupt

The macroscopic entropy and the attractor equations for BPS black holes in four-dimensional N=2 supergravity theories follow from a variational principle for a certain `entropy function&#39;. We present this function in the presence of R^2-interactions and non-holomorphic corrections. The variational principle identifies the entropy as a Legendre transform a

M. Dance

This paper tentatively conjectures a possible physical picture that may help explain links between quantum field theories and string theories. A correspondence might occur if the stringy parameters $τ$ and $σ_i $ are interpreted as representing particular types of observer capabilities. Observer limitations could be imposed by symmetries of relevant quantum

T. Fujita, S. Kanemaki, S. Oshima

We derive a Lagrangian density of Dirac field by employing the local gauge invariance and the Maxwell equation as the fundamental principle. The only assumption made here is that the fermion field should have four components. The present derivation of the Dirac equation does not involve the first quantization, and therefore this study may present an alternat

Hideo Kodama, Kunihito Uzawa

We derive four-dimensional effective theories for warped compactification of the ten-dimensional IIB supergravity. We show that these effective theories allow a much wider class of solutions than the original higher-dimensional theories. This result indicates that the effective four-dimensional theories should be used with caution, if one regards the higher-

Mu-Chun Chen

The little Higgs idea is an alternative to supersymmetry as a solution to the gauge hierarchy problem. In this note, I review various little Higgs models and their phenomenology with emphases on the precision electroweak constraints in these models.

L. Frankurt, V. Guzey, M. Strikman

We review predictions of the theory of leading twist nuclear shadowing for inclusive unpolarized and polarized deuteron structure functions F_2^D, g_1^D and b_1^D and for the tagged deuteron structure function F_2^D(x,Q^2,\vec{p}). We analyze the possibility to extract the neutron structure function F_2^n from electron-deuteron data and demonstrate that an a

A. Denner, S. Dittmaier, M. Roth, L. H. Wieders

The calculation of the full electroweak O(alpha) corrections to the charged-current four-fermion production processes e+e- --> nu_tau tau+ mu- anti-nu_mu, u anti-d mu- anti-nu_mu, and u anti-d s anti-c is briefly reviewed. The calculation is performed using the complex-mass scheme for the gauge-boson resonances. The evaluation of the occurring one-loop tenso

Ulrich Harbach, Marcus Bleicher

We discuss modifications of the neutrino-nucleon cross section due to a minimal length scale. It is shown that the enhancement of the nu-N cross section due to new physics is suppressed. Especially the potential observation rate of micro black holes at neutrino telescopes is strongly reduced.

V. Guzey, M. Siddikov

We perform a microscopic evaluation of nuclear GPDs for spin-0 nuclei in the framework of the Walecka model. We demonstrate that the meson (non-nucleon) degrees of freedom dramatically influence nuclear GPDs, which is revealed in the non-trivial and unexpected A-dependence of DVCS observables. In particular, we find that the first moment of the nuclear D-ter

Christof Gattringer, E. -M. Ilgenfritz, Stefan Solbrig

Starting from thermalized quenched SU(2) configurations we apply cooling or iterated smearing, respectively, to produce sequences of gauge configurations with less and less fluctuations. We compute the low lying spectrum and eigenmodes of the lattice Dirac operator and compare them for the two types of smoothing. Many characteristic properties of the eigensy

J. L Rosner, CLEO Collaboration

We present the first experimental limits on high-q^2 contributions to charmless semileptonic B decays of the form expected from the Weak Annihilation (WA) decay mechanism. Such contributions could bias determinations of |Vub| from inclusive measurements of B-> X_u lnu. Using a wide range of models based on available theoretical input we set a limit of (Gamma

Peter Baekler, Friedrich W. Hehl

Within the framework of metric-affine gravity (MAG, metric and an independent linear connection constitute spacetime), we find, for a specific gravitational Lagrangian and by using {\it prolongation} techniques, a stationary axially symmetric exact solution of the vacuum field equations. This black hole solution embodies a Kerr-deSitter metric and the post-R

G. L. Alberghi, R. Casadio, D. Fazi

We study the collapse towards the gravitational radius of a macroscopic spherical thick shell surrounding an inner massive core. This overall electrically neutral macroshell is composed by many nested delta-like massive microshells which can bear non-zero electric charge, and a possibly non-zero cosmological constant is also included. The dynamics of the she

M. Dyrda, B. Kinasiewicz, M. Kutschera, A. Szmaglinski

Neutron stars are discussed as laboratories of physics of strong gravitational fields. The mass of a neutron star is split into matter energy and gravitational field energy contributions. The energy of the gravitational field of neutron stars is calculated with three different approaches which give the same result. It is found that up to one half of the grav

M. Sharif, Tasnim Fatima

This paper has been addressed to a very old but burning problem of energy in General Relativity. We evaluate energy and momentum densities for the static and axisymmetric solutions. This specializes to two metrics, i.e., Erez-Rosen and the gamma metrics, belonging to the Weyl class. We apply four well-known prescriptions of Einstein, Landau-Lifshitz, Papater

Paul S. Wesson

Using exact solutions, we show that it is in principle possible to regard waves and particles as representations of the same underlying geometry, thereby resolving the problem of wave-particle duality.

Antonio J. Caamaño, Juan J. Vinagre, Mark Wilby, Javier Ramos

In this work we develop a new theory to analyse the process of routing in large-scale ad-hoc wireless networks. We use a path integral formulation to examine the properties of the paths generated by different routing strategies in these kinds of networks. Using this theoretical framework, we calculate the statistical distribution of the distances between any

Remko Tronçon, Gerda Janssens, Bart Demoen, Henk Vandecasteele

Control flow compilation is a hybrid between classical WAM compilation and meta-call, limited to the compilation of non-recursive clause bodies. This approach is used successfully for the execution of dynamically generated queries in an inductive logic programming setting (ILP). Control flow compilation reduces compilation times up to an order of magnitude,

Antonio J. Fernandez, Teresa Hortala-Gonzalez, Fernando Saenz-Perez, Rafael del Vado-Virseda

In this paper, we present our proposal to Constraint Functional Logic Programming over Finite Domains (CFLP(FD)) with a lazy functional logic programming language which seamlessly embodies finite domain (FD) constraints. This proposal increases the expressiveness and power of constraint logic programming over finite domains (CLP(FD)) by combining functional

M. G. Stepanov, M. Chertkov

In this paper we develop instanton method introduced in [1], [2], [3] to analyze quantitatively performance of Low-Density-Parity-Check (LDPC) codes decoded iteratively in the so-called error-floor regime. We discuss statistical properties of the numerical instanton-amoeba scheme focusing on detailed analysis and comparison of two regular LDPC codes: Tanner&

David S. Płaneta

Pbit, besides its simplicity, is definitely the fastest list sorting algorithm. It considerably surpasses all already known methods. Among many advantages, it is stable, linear and be made to run in place. I will compare Pbit with algorithm described by Donald E. Knuth in the third volume of &#39;&#39;The Art of Computer Programming&#39;&#39; and other (Quic

Jesse S. A. Bridgewater, P. Oscar Boykin, Vwani P. Roychowdhury

We present a novel framework, called balanced overlay networks (BON), that provides scalable, decentralized load balancing for distributed computing using large-scale pools of heterogeneous computers. Fundamentally, BON encodes the information about each node&#39;s available computational resources in the structure of the links connecting the nodes in the ne

Natalya A. Zimbovskaya, Vsevolod I. Okulov

The cyclotron-resonance peak which has been observed [G. A. Baraff et al., Phys. Rev. Lett. 22, 590 (1969) ] in potassium in a magnetic field directed perpendicular to the surface may be due to an effect of zero-curvature points of the Fermi surface on the cyclotron orbit of effective electrons.

Taylor L. Hughes, B. Andrei Bernevig, Yaroslaw B. Bazaliy

We find that the spin-charge motion in a strongly confined two-dimensional hole gas (2DHG) supports a propagating mode of cubic dispersion apart from the diffusive mode due to momentum scattering. Propagating modes seem to be a generic property of systems with spin-orbit coupling. Through a rigorous Keldysh approach, we obtain the transport equations for the

N. P. Rapapa, A. J. Bray

We analytically study the effect of a uniform shear flow on the persistence properties of coarsening systems. The study is carried out within the anisotropic Ohta-Jasnow-Kawasaki (OJK) approximation for a system with nonconserved scalar order parameter. We find that the persistence exponent theta has a non-trivial value: theta = 0.5034... in space dimension

W. Janke, D. Johnston, R. Kenna

All of the thermodynamic information on a statistical mechanical system is encoded in the locus and density of its partition function zeroes. Recently, a new technique was developed which enables the extraction of the latter using finite-size data of the type typically garnered from a computational approach. Here that method is extended to deal with more gen

Tomasz Karpiuk, Miroslaw Brewczyk, Kazimierz Rzazewski

We consider the formation of bright solitons in a mixture of Bose and Fermi degenerate gases confined in a three-dimensional elongated harmonic trap. The Bose and Fermi atoms are assumed to effectively attract each other whereas bosonic atoms repel each other. Strong enough attraction between bosonic and fermionic components can change the character of the i

R. Zitko, J. Bonca, A. Ramsak, T. Rejec

Numerical analysis of the simplest odd-numbered system of coupled quantum dots reveals an interplay between magnetic ordering, charge fluctuations and the tendency of itinerant electrons in the leads to screen magnetic moments. The transition from local-moment to molecular-orbital behavior is visible in the evolution of correlation functions as the inter-dot

Ngo Minh Toan, Cristian Micheletti

By resorting to the thick-chain model we discuss how the stretching response of a polymer is influenced by the self-avoidance entailed by its finite thickness. The characterization of the force versus extension curve for a thick chain is carried out through extensive stochastic simulations. The computational results are captured by an analytic expression tha

A. S. Carneiro, R. F. Jardim, F. C. Fonseca

The effects of dc excitation current on the current-voltage curves of polycrystalline samples of Nd0.5Ca0.5Mn0.96Cr0.04O3 were investigated. The experimental results show that an abrupt jump of the voltage is concomitant with a huge increase in the temperature of the sample. A simple model and estimates for Joule self-heating effects support the experimental

J. C. Gonzalez-Avella, V. M. Eguiluz, M. G. Cosenza, K. Klemm

A nonequilibrium system of locally interacting elements in a lattice with an absorbing order-disorder phase transition is studied under the effect of additional interacting fields. These fields are shown to produce interesting effects in the collective behavior of this system. Both for autonomous and external fields, disorder grows in the system when the pro

G. Lamura, M. Aurino, G. Cifariello, E. Di Gennaro

The temperature dependence of the in-plane magnetic penetration depth, $λ_{ab}(T)$, has been measured in a c-axis oriented polycrystalline CaC$_{6}$ bulk sample using a high-resolution mutual inductance technique. A clear exponential behavior of $λ_{ab}(T)$ has been observed at low temperatures, strongly suggesting isotropic s-wave pairing. Data fit using th

M. N. Kiselev

We present a general derivation of semi-fermionic representation for spin operators in terms of a bilinear combination of fermions in real and imaginary time formalisms. The constraint on fermionic occupation numbers is fulfilled by means of imaginary Lagrange multipliers resulting in special shape of quasiparticle distribution functions. We show how Schwing

Jacques Leng, Barbara Lonetti, Patrick Tabeling, Mathieu Joanicot

We use pervaporation-based microfluidic devices to concentrate species in aqueous solutions with spatial and temporal control of the process. Using experiments and modelling, we quantitatively describe the advection-diffusion behavior of the concentration field of various solutions (electrolytes, colloids, etc) and demonstrate the potential of these devices

Ionela Vrejoiu, Gwenael Le Rhun, Lucian Pintilie, Dietrich Hesse

PbZrxTi1-xO3 (PZT) is one of the technologically most important ferroelectric materials. Bulk single-domain single crystals of PZT have never been synthesized for a significant compositional range across the solid-solution phase diagram. This leaves the fundamental properties of PZT under debate. Synthesis of defect-free single crystalline films enables us t

V. I. Yukalov

The theory of turbulent photon filamentation in lasers with high Fresnel numbers is presented. A survey of experimental observations of turbulent filamentation is given. Theoretical description is based on the method of eliminating field variables, which yields the pseudospin laser equations. These are treated by the scale separation approach, including the

A. N. Rubtsov

Diagram series expansion for lattice models with a localized nonlinearity can be renormalized so that diagram vertexes become irreducible vertex parts of certain impurity model. Thus renormalized series converges well in the very opposite cases of tight and weak binding and pretends to describe in a regular way strong-correlated systems with localized intera

Cecile Monthus

After a general introduction to the field, we describe some recent results concerning disorder effects on both `random walk models&#39;, where the random walk is a dynamical process generated by local transition rules, and on `polymer models&#39;, where each random walk trajectory representing the configuration of a polymer chain is associated to a global Bo

A. Sherman

The diagram technique for the one-band Hubbard model is formulated for the case of moderate to strong Hubbard repulsion. The expansion in powers of the hopping constant is expressed in terms of site cumulants of electron creation and annihilation operators. For Green&#39;s function an equation of the Larkin type is derived and solved in a one-loop approximat

Mohammad Mehrafarin

A dynamical model is proposed for isotropic turbulence driven by steady forcing that yields a viscosity independent dynamics for the small-scale (inertial) regime. This reproduces the Kolmogorov spectrum for the two-point velocity correlation function in the fully developed (stationary) stage, while predicting intermittency corrections for higher order momen

Takashi Yanagisawa, Mitake Miyazaki, Kunihiko Yamaji

We propose a $d$-density wave induced by the spin-orbit coupling in the CuO plane. The spectral function of high-temperature superconductors in the under doped and lightly doped regions is calculated in order to explain the Fermi arc spectra observed recently by angle-resolved photoemission spectroscopy. We take into account the tilting of CuO octahedra as w

Stephen R. Williams, Debra J. Searles, Denis J. Evans

A thermostatted dynamical model with five degrees of freedom is used to test both the Evans-Searles and the Gallavotti-Cohen fluctuation relations (ESFR and GCFR respectively). In the absence of an external driving field, the model generates a time independent ergodic equilibrium state with two conjugate pairs of Lyapunov exponents. Each conjugate pair sums

Ki-Seok Kim

We investigate the role of disorder in the Mott-Hubbard transition based on the slave-rotor representation of the Hubbard model, where an electron is decomposed into a fermionic spinon for a spin degree of freedom and a bosonic rotor (chargon) for a charge degree of freedom. In the absence of disorder the Mott-Hubbard insulator is assumed to be the spin liqu

R. J. Baxter

It has been known for some time that the Boltzmann weights of the chiral Potts model can be parametrized in terms of hyperelliptic functions, but as yet no such parametrization has been applied to the partition and correlation functions. Here we show that for N=3 the function $S(t_p)$ that occurs in the recent calculation of the order parameters can be expre

D. N. H. Nam, L. V. Bau, N. V. Khiem, N. V. Dai

The magnetic lattice of mixed-valence Mn ions in La$_{0.7}$Sr$_{0.3}$MnO$_3$ is selectively diluted by partial substitution of Mn by Al or Ti. The ferromagnetic transition temperature and the saturation moment decreases with substitution in both series. The volume fraction of the non-ferromagnetic phases evolves non-linearly with the substitution concentrati

Ana Maria Rey, Indubala I. Satija, Charles W. Clark

We use Hanbury-Brown-Twiss interferometry (HBTI) to study various quantum phases of hard core bosons (HCBs) and ideal fermions confined in a one-dimensional quasi-periodic (QP) potential. For HCBs, the QP potential induces a cascade of Mott-like band-insulator phases in the extended regime, in addition to the Mott insulator, Bose glass, and superfluid phases

Atsushi Hatakeyama, Markus Wilde, Katsuyuki Fukutani

We attempt to provide physical interpretations of light-induced desorption phenomena that have recently been observed for alkali atoms on glass surfaces of alkali vapor cells used in atomic physics experiments. We find that the observed desorption phenomena are closely related to recent studies in surface science, and can probably be understood in the contex

Uma Divakaran, Amit Dutta

We study random fiber bundle model (RFBM) with different threshold strength distributions and load sharing rules. A mixed RFBM within global load sharing scheme is introduced which consists of weak and strong fibers with uniform distribution of threshold strength of fibers having a discontinuity. The dependence of the critical stress of the above model on th

Yunori Nisikawa, Akira Oguri

The ground-state properties of quartet quantum-dot arrays are studied using the numerical renormalization group (NRG) method with a four-site Hubbard model connected to two non-interacting leads. Specifically, we calculate the conductance and local charge in the dots from the many-body phase shifts, which can be deduced from the fixed-point eigenvalues of NR

J. M. Teixeira, R. F. A. Silva, J. Ventura, A. M. Pereira

We present a detailed study on domain imaging, Kerr effect magnetometry (MOKE) and magnetoresistance (MR), for a series of 20 nm Co$_{73.8}$Fe$_{16.2}$B$_{10}$ thin films, both as-deposited (amorphous) and annealed (crystalline). By considering the two different (orthogonal) in-plane magnetization components, obtained by MOKE measurements, we were able to st

I. B. Bischofs, U. S. Schwarz

Compliant environments can mediate interactions between mechanically active cells like fibroblasts. Starting with a phenomenological model for the behaviour of single cells, we use extensive Monte Carlo simulations to predict non-trivial structure formation for cell communities on soft elastic substrates as a function of elastic moduli, cell density, noise a

Saar Rahav, Piet W. Brouwer

We investigate the behavior of weak localization, conductance fluctuations, and shot noise of a chaotic scatterer in the semiclassical limit. Time resolved numerical results, obtained by truncating the time-evolution of a kicked quantum map after a certain number of iterations, are compared to semiclassical theory. Considering how the appearance of quantum e