April 2004 arXiv papers — page 4

G. Akemann, A. Pottier

We compute correlation functions of inverse powers and ratios of characteristic polynomials for random matrix models with complex eigenvalues. Compact expressions are given in terms of orthogonal polynomials in the complex plane as well as their Cauchy transforms, generalizing previous expressions for real eigenvalues. We restrict ourselves to ratios of char

D. Cremades, L. E. Ibanez, F. Marchesano

We compute Yukawa couplings involving chiral matter fields in toroidal compactifications of higher dimensional super-Yang-Mills theory with magnetic fluxes. Specifically we focus on toroidal compactifications of D=10 super-Yang-Mills theory, which may be obtained as the low-energy limit of Type I, Type II or Heterotic strings. Chirality is obtained by turnin

Gabriele Tartaglino-Mazzucchelli

We give the superfield quantization of chiral/nonminimal (CNM) scalar multiplets defined by pairs of N=1 chiral and complex linear scalar superfields kinematically coupled. In the pure massive case we develop the covariant quantization when CNM multiplets are coupled to background gauge superfields. Furthermore, we study some properties of N=1 supersymmetric

Nikita Nekrasov, Sergey Shadchin

We solve N=2 supersymmetric Yang-Mills theories for arbitrary classical gauge group, i.e. SU(N), SO(N), Sp(N). In particular, we derive the prepotential of the low-energy effective theory, and the corresponding Seiberg-Witten curves. We manage to do this without resolving singularities of the compactified instanton moduli spaces.

Vivina Barutello, Davide L. Ferrario, Susanna Terracini

We consider periodic and quasi-periodic solutions of the three-body problem with homogeneous potential from the point of view of the equivariant calculus of variations. First, we show that symmetry groups of the Lagrangian action functional can be reduced to groups in a finite explicitly given list, after a suitable change of coordinates. Then, we show that

Marija Dimitrijevic, Lutz Möller, Efrossini Tsouchnika

The model of kappa-deformed space is an interesting example of a noncommutative space, since it allows a deformed symmetry. In this paper we present new results concerning different sets of derivatives on the coordinate algebra of kappa-deformed Euclidean space. We introduce a differential calculus with two interesting sets of one-forms and higher-order form

Carlo Ewerz, Otto Nachtmann

This is the first of two papers in which we study real and virtual photon-proton scattering in a nonperturbative framework. We classify different contributions to this process and identify the leading contributions at high energies. We then study the renormalisation of the photon-quark-antiquark vertex that occurs in the leading contributions. We find someth

Ashok Das, Ziemowit Popowicz

In this paper, we study the properties of a nonlinearly dispersive integrable system of fifth order and its associated hierarchy. We describe a Lax representation for such a system which leads to two infinite series of conserved charges and two hierarchies of equations that share the same conserved charges. We construct two compatible Hamiltonian structures

Mayeul Arminjon

The construction of the scalar theory based on the concept of gravity as Archimedes' thrust is briefly summarized, emphasizing the two (extreme) possibilities that result from this concept for the gravitational rod contraction: it can either occur in only one direction, or be isotropic. A modified equation for the scalar field is stated for the new, isotropi

Valeri N. Kotov, Michael E. Zhitomirsky, Maged Elhajal, Frederic Mila

We analyze the phases of an S=1/2 spin model on a lattice of coupled tetrahedra. The presence of both Heisenberg and antisymmetric, Dzyaloshinsky-Moriya interactions can lead to two types of symmetry-broken states: non-magnetic dimer order and, unexpectedly, exotic 4 sub-lattice weak antiferromagnetic order - a state with a generically small ordered moment a

A. Z. Zhou, R. X. Xu, X. J. Wu, N. Wang

A starquake mechanism for pulsar glitches is developed in the solid quark star model. It is found that the general glitch natures (i.e., the glitch amplitudes and the time intervals) could be reproduced if solid quark matter, with high baryon density but low temperature, has properties of shear modulus μ= 10^{30~34} erg/cm^3 and critical stress σ_c = 10^{18~

Almut Beige, Peter L. Knight, Giuseppe Vitiello

We propose a mechanism for the collective cooling of a large number N of trapped particles to very low temperatures by applying red-detuned laser fields and coupling them to the quantized field inside an optical resonator. The dynamics is described by what appears to be rate equations, but where some of the major quantities are coherences and not populations

Surajit Dasgupta, A. R. Rao, G. C. Dewangan

We present results based on an XMM-Newton observation of the high luminosity narrow-line QSO PHL 1092 performed in 2003 January. The 0.3 - 10 keV spectrum is well described by a model which includes a power-law (Gamma ~ 2.1) and two blackbody components (kT ~ 130 eV and kT ~ 50 eV). The soft X-ray excess emission is featureless and contributes ~ 80% to the t

B. Abdullaev, C. -H. Park

A ground state energy variational calculation of anyon gas with Hamiltonian included the interaction of spins of particles with anyon vector potential induced, i.e. statistical, magnetic field exhibits exact cancelation of terms connected with fractional statistics. This leads to bosonization of anyons due to coupling of their spins with statistical magnetic

Sylvie Corteel, Jeremy Lovejoy

We start with a bijective proof of Schur's theorem due to Alladi and Gordon and describe how a particular iteration of it leads to some very general theorems on colored partitions. These theorems imply a number of important results, including Schur's theorem, Bressoud's generalization of a theorem of Göllnitz, two of Andrews' generalizations

Andrei V. Frolov

The intent of this letter is to point out that the accretion of a ghost condensate by black holes could be extremely efficient. We analyze steady-state spherically symmetric flows of the ghost fluid in the gravitational field of a Schwarzschild black hole and calculate the accretion rate. Unlike minimally coupled scalar field or quintessence, the accretion r

A. Niegawa

We investigate the magnetic property of the cold quark matter employing the magnetic moment $\vecμ'$ as the order parameter. Through analysis of the effective potential $V (\vecμ^{' 2})$, we find that, at relatively high densities $ρ> ρ_c$, the quark matter is in the normal phase. At $ρ= ρ_c$, the magnetic phase transition takes place and, in the low

P. Wang, D. B. Leinweber, A. W. Thomas, A. G. Williams

We perform a study of infinite hadronic matter, finite nuclei and hypernuclei with an improved method of calculating the effective baryon mass. A detailed study of the predictions of the model is made in comparison with the available data and the level of agreement is generally very good. Comparison with an earlier treatment shows relatively minor difference

Steven B. Giddings, Robert C. Myers

Positive vacuum energy together with extra dimensions of space imply that our four-dimensional Universe is unstable, generically to decompactification of the extra dimensions. Either quantum tunneling or thermal fluctuations carry one past a barrier into the decompactifying regime. We give an overview of this process, and examine the subsequent expansion int

T. Sawa, M. Fujimoto

We propose a new model for the origin and evolution of the Local Group of Galaxies (LGG) which naturally explains the formation of the Magellanic Clouds and their large orbital angular momenta around the Galaxy. The basic idea is that an off-center hydrodynamical collision occurred some 10 Gyr ago between the primordial gas-rich Andromeda galaxy and the simi

Puneet Batra, Antonio Delgado, David E. Kaplan, Tim M. P. Tait

The LEP-II bound on the light Higgs mass rules out the vast majority of parameter space left to the Minimal Supersymmetric Standard Model (MSSM) with weak-scale soft-masses. This suggests the importance of exploring extensions of the MSSM with non-minimal Higgs physics. In this article, we explore a theory with an additional singlet superfield and an extende

A. Gangat, P. Pradhan, G. Pati, M. S. Shahriar

We propose a novel scheme for the lithography of arbitrary, two-dimensional nanostructures via matter-wave interference. The required quantum control is provided by a pi/2-pi-pi/2 atom interferometer with an integrated atom lens system. The lens system is developed such that it allows simultaneous control over atomic wave-packet spatial extent, trajectory, a

Kazuyuki Fujii, Kyoko Higashida, Ryosuke Kato, Tatsuo Suzuki

In this letter the explicit form of evolution operator of three atoms Tavis-Cummings model is given, which is a generalization of the paper quant-ph/0403008.

Constantin V. Usenko, Vladyslav C. Usenko

The data transmission protocol, based on the use of a strongly correlated pair of laser beams, is proposed. The properties of the corresponding states are described in detail. The protocol is based on the strong correlation of photon numbers in both beams in each measurement. The protocol stability against the interception attempts is analyzed.

Vladislav S. Olkhovsky, Sergei P. Maydanyuk

The Poincare's period of particle oscillations between wells is obtained in double-well potential. The dependencies of oscillation period on transmission coefficient on distance between levels are obtained. The cases of squared potentials and some potentials having rounded off forms are considered.

Arnold J. Storm, Cornelis Storm, Jianghua Chen, Henny Zandbergen

We report translocation experiments on double-strand DNA through a silicon oxide nanopore. Samples containing DNA fragments with seven different lengths between 2000 to 96000 basepairs have been electrophoretically driven through a 10 nm pore. We find a power-law scaling of the translocation time versus length, with an exponent of 1.26 $\pm$ 0.07. This behav

Boris Shakhnovich, Eric Deeds, Charles Delisi, Eugene Shakhnovich

Understanding the observed variability in the number of homologs of a gene is a very important, unsolved problem that has broad implications for research into co-evolution of structure and function, gene duplication, pseudogene formation and possibly for emerging diseases. Here we attempt to define and elucidate the reasons behind this observed unevenness in

P. Leifer

The covariant formulation of the quantum dynamics in CP(1) should lead to the observable geometrodynamical effects for the local dynamical variable of the light polarization states.

C. P. Hauri, P. Schlup, G. Arisholm, J. Biegert

Phase-stabilized 12-fs, 1-nJ pulses from a commercial Ti:sapphire oscillator are directly amplified in a chirped-pulse optical parametric amplifier and recompressed to yield near-transform-limited 17.3-fs pulses. The amplification process is demonstrated to be phase preserving and leads to 85-uJ, carrier-envelope-offset phase-locked pulses at 1 kHz for 0.9 m

F. L. Marquezino, R. R. Mello Junior

This article is a short review on the concept of information. We show the strong relation between Information Theory and Physics, and the differences between classical and quantum information, with emphasis in their manipulation through logical gates. This paper is intended to be read by non-specialists and undergraduate students of Computer Science, Mathema

F. L. Marquezino, R. R. Mello Junior

This article is a short review on the concept of information. We show the strong relation between Information Theory and Physics, beginning by the concept of bit and its representation with classical physical systems, and then going to the concept of quantum bit (the so-called ``qubit'') and exposing some differences and similarities. This paper is i

L. N. Labzowsky, A. V. Shonin, D. A. Solovyev

The quantum electrodynamical theory of the two-photon transitions in hydrogenlike ions is presented. The emission probability for 2s1/2 -> 2E1+1s1/2 transitions is calculated and compared to the results of the previous calculations. The emission probabilities 2p12 -> E1E2+1s1/2 and 2p1/2 -> E1M1+1s1/2 are also calculated for the nuclear charge Z values 1-100

Liang-shan Chen, Zhen Ye

The propagation of surface water waves over rough topographical bottoms is investigated by the multiple scattering theory. It is shown that the waves can be localized spatially through the process of multiple scattering and wave interference, a peculiar wave phenomenon which has been previously discussed for frozen light in optical systems (S. John, Nature {

Simona Blanca Savescu

Biological cell suspensions are known to show dielectric dispersions due to the Maxwell-Wagner mechanism. Many examples are summarized in a number of papers by Schwan [7, 9, 10]. By the application of an appropriate analysis to the dielectric dispersion, it is possible to estimate electrical phase parameters related to protoplasm and cell membrane. A dielect

R. Schiavilla, J. Carlson, M. Paris

We investigate parity-violating observables in the np system, including the longitudinal asymmetry and neutron-spin rotation in np elastic scattering, the photon asymmetry in np radiative capture, and the asymmetries in deuteron photo-disintegration d(gamma,n)p in the threshold region and electro-disintegration d(e,e`)np in quasi-elastic kinematics. To have

Hirofumi Ohta, Kazuhiro Yabana, Takashi Nakatsukasa

A self-consistent calculation with variation after parity projection is proposed to study both ground and excited states of light nuclei. This procedure provides description of the ground state incorporating some correlation effects, and self-consistent solutions for the excited states of negative parity. For flexible description of nuclear shapes, single pa

Renat Kh. Gainutdinov, Aigul A. Mutygullina

We show that from analysis of time-ordered diagrams for the two-nucleon $T$-matrix in chiral perturbation theory it follows that low energy nucleon dynamics is governed by the generalized dynamical equation, which was derived in [J.Phys.A., v.32, p.5657 (1999)], with a nonlocal-in-time interaction operator. An operator is presented that parametrizes the nucl

V. Blideanu, F. R. Lecolley, J. F. Lecolley, T. Lefort

Double-differential cross sections for light charged particle production (up to A=4) were measured in 96 MeV neutron-induced reactions, at TSL laboratory cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U, were performed using two independent devices, SCANDAL and MEDLEY. The data were recorded with low energy thresholds and for a wi

I. Matea, G. Georgiev, J. M. Daugas, M. Hass

We report on the g factor measurement of the isomer in $^{61}Fe$ ($E^{*}=861 keV$). The isomer was produced and spin-aligned via a projectile-fragmentation reaction at intermediate energy, the Time Dependent Perturbed Angular Distribution (TDPAD) method being used for the measurement of the g factor. For the first time, due to significant improvements of the

FOPI Collaboration, W. Reisdorf

We present a complete systematics (excitation functions and system-size dependences) of global stopping and sideflow for heavy ion reactions in the energy range between 0.09A GeV and 1.93A GeV. For the heaviest system, Au+Au, we observe a plateau of maximal stopping extending from about 0.2A to 0.8A GeV with a fast drop on both sides. The degree of stopping,

John R. Royer, Patrick O'Neill, Nathan Becker, Guenter Ahlers

We present experimental results for Rayleigh-Benard convection patterns in a cylindrical container with static side-wall forcing induced by a heater. This forcing stabilized a pattern of concentric rolls (a target pattern) with the central roll (the umbilicus) at the center of the cell after a jump from the conduction to the convection state. A quasi-static

E. M. Shahverdiev, R. A. Nuriev, R. H. Hashimov, K. A. Shore

We investigate synchronization between two unidirectionally linearly coupled chaotic non-identical time-delayed systems and show that parameter mismatches are of crucial importance to achieve synchronization. We establish that independent of the relation between the delay time in the coupled systems and the coupling delay time, only retarded synchronization

Pratip Bhattacharyya

A brief introduction to Wolfram's work on cellular automata.

Sergej A. Choroszavin

We construct linear Hamilton systems without usual dichotomy property. The Ljapunov spectra of these systems are unfamiliar and conflicting, the behaviour of trajectories is very complicated. The paper's subject refers to some problems of indefinite inner product methods in the stability theory of abstract dynamical equation solutions.

Tomas Ekholm, Hynek Kovarik

The spectrum of the Schrödinger operator in a quantum waveguide is known to be unstable in two and three dimensions. Any enlargement of the waveguide produces eigenvalues beneath the continuous spectrum. Also if the waveguide is bent eigenvalues will arise below the continuous spectrum. In this paper a magnetic field is added into the system. The spectrum of

J. E. McCarthy, Mihai Putinar

A Hilbert space approach to the classical Fantappie transform, based on the concept of Gel'fand triples of locally convex spaces, leads to a novel proof of Martineau-Aizenberg duality theorem. A study of Fantappie transforms of positive measures on the unit ball in $\C^n$ relates ideas of realization theory of multivariate linear systems, locally convex

David Eisenbud, Mark Green, Klaus Hulek, Sorin Popescu

In this paper we derive geometric consequences from the presence of a long strand of linear syzygies in the minimal free resolution of a closed scheme in projective space whose homogeneous ideal is generated by quadrics. These consequences are given in terms of intersections with arbitrary linear subspaces. We use our results to bound homological invariants

Daniel Juan-Pineda, Stratos Prassidis

We use a hocolim approach to the Isomorphism Conjecture in K-Theory to analyze the case of groups of the form $G\rtimes Z$ and $G_1*_{G}G_2$. As an important corollary we prove that the isomorphism conjecture in K-Theory holds for a finitely generated free group.

Boris Hollas

We consider topological indices I that are sums of f(deg(u)) f(deg(v)), where {u,v} are adjacent vertices and f is a function. The Randi{ć} connectivity index or the Zagreb group index are examples for indices of this kind. In earlier work on topological indices that are sums of independent random variables, we identified the correlation between I and the ed

Francesco Delli Priscoli, Lorenzo Marconi, Alberto Isidori

This paper shows how the theory of adaptive observers can be effectively used in the design internal models for nonlinear output regulation. The main result obtained in this way is a new method for the synthesis of adaptive internal models which substantially enhances the existing theory of adaptive output regulation, by allowing nonlinear internal models an

Nobuya Sato

In this article, we will prove that the subsectors of $α$-induced sectors for $M \rtimes \hat{G} \supset M$ forms a modular category, where $M \rtimes \hat{G}$ is the crossed product of $M$ by the group dual $\hat{G}$ of a finite group $G$. In fact, we will prove that it is equivalent to Müger's crossed product. By using this identification, we will exhi

L. R. G. Fontes, M. Isopi, C. M. Newman, K. Ravishankar

Coarsening on a one-dimensional lattice is described by the voter model or equivalently by coalescing (or annihilating) random walks representing the evolving boundaries between regions of constant color and by backward (in time) coalescing random walks corresponding to color genealogies. Asympotics for large time and space on the lattice are described via a

Amy M. Fu, Alain Lascoux

We generalize and prove conjectures of Corteel and Lovejoy, related to overpartitions and divisor functions.

Tomasz Brzezinski

Galois comodules of a coring are studied. The conditions for a simple comodule to be a Galois comodule are found. A special class of Galois comodules termed principal comodules is introduced. These are defined as Galois comodules that are projective over their comodule endomorphism rings. A complete description of principal comodules in the case a background

Jeremy L. Martin

We study the space ${\mathcal X}^{d}(G)$ of pictures of a graph $G$ in complex projective $d$-space. The main result is that the homology groups (with integer coefficients) of ${\mathcal X}^{d}(G)$ are completely determined by the Tutte polynomial of $G$. One application is a criterion in terms of the Tutte polynomial for independence in the {\it $d$-paralle

Brian E. Forrest, Volker Runde

Let $G$ be a locally compact group. We show that its Fourier algebra $A(G)$ is amenable if and only if $G$ has an abelian subgroup of finite index, and that its Fourier-Stieltjes algebra $B(G)$ is amenable if and only if $G$ has a compact, abelian subgroup of finite index. We then show that $A(G)$ is weakly amenable if the component of the identity of $G$ is

M. Rosenbaum, J. D. Vergara

Using normal coordinates in a Poincaré-Birkhoff-Witt basis for the Hopf algebra of renormalization in perturbative quantum field theory, we investigate the relation between the twisted antipode axiom in that formalism, the Birkhoff algebraic decomposition and the universal formula of Kontsevich for quantum deformation.

Ram Brustein, David Eichler, Stefano Foffa

Entropy bounds applied to a system of N species of light quantum fields in thermal equilibrium at temperature T are saturated in four dimensions at a maximal temperature T_max=M_Planck/N^1/2. We show that the correct setup for understanding the reason for the saturation is a cosmological setup, and that a possible explanation is the copious production of bla

Noriko Nakayama, Katsuyuki Sugiyama

We study D-branes of N=2 supersymmetric sigma models. Supersymmetric nonlinear sigma models with 2-dimensional target space have D0,D1,D2-branes, which are realized as A-,B-type supersymmetric boundary conditions on the worldsheet. When we embed the models in the string theory, the Kahler potential is restricted and leads to a 2-dim black hole metric with a

Jorgen Rasmussen

We discuss the link between string backgrounds and the associated world-sheet CFTs. In the search for new backgrounds and CFTs, Penrose limits and Lie algebra contractions are important tools. The Nappi-Witten construction and the recently discovered logarithmic CFT by Bakas and Sfetsos, are considered as illustrations. We also speculate on possible extensio

Anton Rebhan, Peter van Nieuwenhuizen, Robert Wimmer

We discuss the one-loop quantum corrections to the mass M and central charge Z of supersymmetric solitons: the kink, the vortex and the monopole. Contrary to previous expectations and published results, in each of these cases there are nonvanishing quantum corrections to the mass. For the N=1 kink and the N=2 monopole a new anomaly in Z rescues BPS saturatio

E. G. Floratos, J. Iliopoulos

We propose a formulation of d-dimensional SU(N) Yang-Mills theories on a d+2-dimensional space with the extra two dimensions forming a surface with non-commutative geometry. This equivalence is valid in any finite order in the 1/N expansion.

Alex Flournoy, Brian Wecht, Brook Williams

In this paper we investigate compactifications of the type II and heterotic string on four-dimensional spaces with nongeometric monodromies. We explicitly construct backgrounds which contain the "Duality Twists" discussed by Dabholkar and Hull. Similar constructions of nongeometric backgrounds have been discussed for type II strings by Hellerman, McG

A. M. Gavrilik, I. I. Kachurik, A. V. Tertychnyj

Masses of baryons {3/2}^+ are calculated on the base of representations of dynamical "pseudounitary" q-deformed algebra u(4,1)_q which provides necessary breaking of the 4-flavor symmetry realized by the assumed q-algebra su(4)_q. It is demonstrated that, contrary to the case of su(3)_q octet baryons {1/2}^+, one and the same q-analog of mass relatio

Shahid Hussain, Douglas W. McKay

We show that LSG model predictions of event ratios are clearly distinguished from those of the SM. This is true in all models of ultrahigh energy (UHE) neutrino sources, in both $ν_e:ν_μ:ν_τ = 1:1:1$ and $ν_e:ν_μ:ν_τ = 1:2:0$ scenarios for the flux incident on earth. In particular the ratios of upward $μ$ events to upward shower events and the ratios of up e

V. K. Magas

A model for the $Q^2$-dependent dual amplitude with Mandelstam analyticity (DAMA) is proposed. The modified DAMA (M-DAMA) preserves all the attractive properties of DAMA, such as its pole structure and Regge asymptotics, and leads to a generalized dual amplitude $A(s,t,Q^2)$. This generalized amplitude can be checked in the known kinematical limits, i.e. it

Maki Ikegami, Takeo Moroi

We discuss the curvaton scenario with the Affleck-Dine baryogenesis. In this scenario, non-vanishing baryonic entropy fluctuation may be generated even without primordial fluctuation of the Affleck-Dine field. Too large entropy fluctuation is inconsistent with the observations and hence constraints on the curvaton scenario with the Affleck-Dine baryogenesis

S. M. H. Wong

Experimental measurement of the elliptic flow parameter $v_2$ and hydrodynamic model together showed that thermalization in the central region at the Relativistic Heavy Ion Collider to be perplexingly fast. This is a mystery in itself since none of the numerical perturbative QCD models are able to achieve such a feat. By exploiting a theoretical oversight on

G. Wilk, Z. Wlodarczyk

We demonstrate that hadron production viewed as formation of specific stochastic network can explain in natural way the power-law distributions of transverse mass spectra of pions found recently, which seem to substitute the expected Boltzmann statistical factor.

Hiroaki Abuki

This paper has been withdrawn by the author due to a crucial error.

Brigitte Vachon

The differential cross-section for the process e+e- -> γγis calculated assuming the presence of excited electrons with a chiral magnetic coupling. This calculation permits constraining the excited electron coupling using the same theoretical framework as the one generally used for direct production searches.

A. Badertscher, P. Crivelli, W. Fetscher, S. N. Gninenko

We propose an experiment to search for invisible decays of orthopositronium (o-Ps) with a 90% confidence sensitivity in the branching ratio as low as $10^{-8}$. Evidence for this decay mode would unambigously signal new physics: either the existence of extra--dimensions or fractionally charged particles or new light gauge bosons. The experimental approach an

E. M. O'Shea

Recently we studied the effects of information carrying waves propagating through isotropic cosmologies. By information carrying we mean that the waves have an arbitrary dependence on a function. We found that the waves introduce shear and anisotropic stress into the universe. We then constructed explicit examples of pure gravity wave perturbations for which

M. I. Wanas

Non Conventional treatments in modern cosmology, in both Steady State and Big Bang, are given. The motivation behind these treatments is to solve some of the problems of the conventional treatments in cosmology. For this aim, different geometric structures and alternative field theories, used to construct world models, are given. A brief review of Absolute p

S. Capozziello, V. F. Cardone, S. Carloni, A. Troisi

Higher order curvature gravity has recently received a lot of attention due to the fact that it gives rise to cosmological models which seem capable of solving dark energy and quintessence issues without using "ad hoc" scalar fields. In this letter, a gravitational potential is obtained which differs from the Newtonian one because of a repulsive corr

Luca Bombelli, Oliver Winkler

One of the predictions of quantum gravity phenomenology is that, in situations where Planck-scale physics and the notion of a quantum spacetime are relevant, field propagation will be described by a modified set of laws. Descriptions of the underlying mechanism differ from model to model, but a general feature is that electromagnetic waves will have non-triv

Jan Poland, Marcus Hutter

We study the properties of the Minimum Description Length principle for sequence prediction, considering a two-part MDL estimator which is chosen from a countable class of models. This applies in particular to the important case of universal sequence prediction, where the model class corresponds to all algorithms for some fixed universal Turing machine (this

V. M. Apel, Maria A. Davidovich, E. V. Anda, G. Chiappe

The transport properties of a system of two interacting dots, one of them directly connected to the leads constituting a side-coupled configuration (SCD), are studied in the weak and strong tunnel-coupling limits. The conductance behavior of the SCD structure has new and richer physics than the better studied system of two dots aligned with the leads (ACD).

R. C. Rai, J. W. Brill

We have observed a large (~1%) change in infrared reflectance of the charge-density-wave (CDW) conductor, orthorhombic TaS3, when its CDW is depinned. The change is concentrated near one current contact. Assuming that the change in reflectance is proportional to the degree of CDW polarization, we have studied the dynamics of CDW repolarization through positi

Grzegorz Szamel

Using memory-function formalism we show that in sheared colloidal suspensions the fluctuation-dissipation theorem for self-diffusion, i.e. Einstein's relation between self-diffusion and mobility tensors, is violated and propose a new way to measure this violation in Brownian Dynamics simulations. We derive mode-coupling expressions for the tagged particl

Hyunbum Jang, Malcolm J. Grimson, Thomas B. Woolf

The dynamic phase behavior of a classical Heisenberg spin system with a bilinear exchange anisotropy in a planar thin film geometry has been investigated by Monte Carlo simulations using different forms for the stochastic dynamics. In simulations of the dynamic phase transition (DPT) in films subject to a pulsed oscillatory external field with competing surf

Rui Vilela Mendes, Maria Joao Oliveira

Based on empirical market data, a stochastic volatility model is proposed with volatility driven by fractional noise. The model is used to obtain a risk-neutrality option pricing formula and an option pricing equation.

Amir Hossein Darooneh

We find the wealth distribution for an economic agent in the financial market, in analogy with standard derivation of generaliz Boltzman (Tsallis) factor in statistical mechanics. In this respect, Tsallis entropic index separates two different regimes, the large and small size market. The Pareto like wealth distribution is obtained in the case of small size

V. N. Zavaritsky, A. S. Alexandrov

High magnetic field studies of the cuprate superconductors revealed a non-BCS temperature dependence of the upper critical field $H_{c2}(T)$ determined resistively by several groups. These determinations caused some doubts on the grounds of the contrasting effect of the magnetic field on the in-plane, $ρ_{ab}$, and out-of-plane, $ρ_{c}$ resistances reported

M. B. Tavernier, E. Anisimovas, F. M. Peeters

Exact many-body wave functions for quantum dots containing up to four interacting electrons are computed and we investigated the distribution of the wave function nodes, also called vortices. For this purpose, we evaluate the reduced wave function by fixing the positions of all but one electron and determine the locations of its zeros. We find that the zeros

T. Kühn, D. V. Anghel, J. P. Pekola, M. Manninen

Phonon modes and their dispersion relations in ultrathin homogenous dielectric membranes are calculated using elasticity theory. The approach differs from the previous ones by a rigorous account of the effect of the film surfaces on the modes with different polarizations. We compute the heat capacity of membranes and the heat conductivity of narrow bridges c

J. Reinisch, A. Heuer

Via computer simulations of the standard binary Lennard-Jones glass former we have obtained in a systematic way a large set of close-by pairs of minima on the potential energy landscape, i.e. double-well potentials (DWP). We analyze this set of DWP in two directions. At low temperatures the symmetric DWP give rise to tunneling systems. We compare the resulti

S. De Palo, M. L. Chiofalo, M. J. Holland, S. J. J. M. F. Kokkelmans

Feshbach scattering resonances are being utilized in atomic gases to explore the entire crossover region from a Bose-Einstein Condensation (BEC) of composite bosons to a Bardeen-Cooper-Schrieffer (BCS) of Cooper pairs. Several theoretical descriptions of the crossover have been developed based on an assumption that the fermionic interactions are dependent on

R. N. Gurzhi, A. N. Kalinenko, A. I. Kopeliovich, A. V. Yanovsky

A method for the evaluation of the angular width of an electron beam generated by a nanoconstriction is proposed and demonstrated. The approach is based on analysis of a narrow-width electron flow, that quantizes into modes inside a confining constriction which is described in the adiabatic approximation, evolving into a freely propagating electronic state a

J. E. Inglesfield, J. M. Pitarke, R. Kemp

The photonic band structure of a three-dimensional lattice of metal spheres is calculated using an embedding technique, in the frequency range of the Mie plasmons. For a small filling factor of the spheres, Maxwell-Garnett theory gives an almost exact description of the dipole modes, and the multipole modes are fairly dispersionless. For a larger filling fac

P. -O. Jubert, R. Allenspach, A. Bischof

Magnetic domain walls have been studied in micrometer-sized Fe20Ni80 elements containing geometrical constrictions by spin-polarized scanning electron microscopy and numerical simulations. By controlling the constriction dimensions, the wall width can be tailored and the wall type modified. In particular, the width of a 180 degree Neel wall can be strongly r

L. Plaja, J. San Roman

We present a detailed description of the formation of bright solitary waves in optical lattices. To this end, we have considered a ring lattice geometry with large radius. In this case, the ring shape does not have a relevant effect in the local dynamics of the condensate, while offering a realistic set up to implement experiments with conditions usually not

Z. Rapti, G. Theocharis, P. G. Kevrekidis, D. J. Frantzeskakis

We investigate the modulational instability of nonlinear Schr{ö}dinger equations with periodic variation of their coefficients. In particular, we focus on the case of the recently proposed, experimentally realizable protocol of Feshbach Resonance Management for Bose-Einstein condensates. We derive the corresponding linear stability equation analytically and

R. Moriya, K. Hamaya, A. Oiwa, H. Munekata

We report current-induced magnetization reversal in a ferromagnetic semiconductor-based magnetic tunnel junction (Ga,Mn)As/AlAs/(Ga,Mn)As prepared by molecular beam epitaxy on a p-GaAs(001) substrate. A change in magneto-resistance that is asymmetric with respect to the current direction is found with the excitation current of 10^6 A/cm^2. Contributions of b

G. Theocharis, Z. Rapti, P. G. Kevrekidis, D. J. Frantzeskakis

The modulational stability of the nonlinear Schr{ö}dinger (NLS) equation is examined in the case with a quadratic external potential. This study is motivated by recent experimental studies in the context of matter waves in Bose-Einstein condensates (BECs). The theoretical analysis invokes a lens-type transformation that converts the Gross-Pitaevskii into a r

A. V. Lopatin, N. Shah, V. M. Vinokur

We calculate the fluctuation correction to the normal state conductivity in the vicinity of a quantum phase transition from a superconducting to normal state, induced by applying a magnetic field parallel to a dirty thin film or a nanowire with thickness smaller than the superconducting coherence length. We find that at zero temperature, where the correction

Guangyong Xu, Z. Zhong, H. Hiraka, G. Shirane

High energy (67 keV) x-ray diffuse scattering measurements were performed on single crystals of Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$-$x$PbTiO$_3$ (PZN-$x$PT). A novel technique was developed to map out the diffuse scattering distribution in all three dimensions around a large number of Bragg peaks simultaneously, taking advantage of the almost flat Ewald sphere of

Qiuping A. Wang

The nonextensive statistics based on Tsallis entropy have been so far used for the systems composed of subsystems having same $q$. The applicability of this statistics to the systems with different $q$'s is still a matter of investigation. The actual difficulty is that the class of systems to which the theory has been applied is limited by the usual nona

Nimrod Moiseyev, L. D. Carr, Boris A. Malomed, Y. B. Band

It is shown using the Gross-Pitaevskii equation that resonance states of Bose-Einstein condensates with attractive interactions can be stabilized into true bound states. A semiclassical variational approximation and an independent quantum variational numerical method are used to calculate the energies (chemical potentials) and linewidths of resonances of the

Alexander Kusenko

The physics of the supernova may provide a clue of the cosmological dark matter. In the absence of new physics, the supernova calculations do not explain the observed velocities of pulsars. However, if there exists a singlet fermion with mass in the 1-20 keV range and a small mixing with neutrinos, this particle could be emitted asymmetrically from a cooling