August 2002 arXiv papers — page 4

S. Kimeswenger, C. Lederle, S. Schmeja, B. Armsdorfer

V838 Mon underwent, after a first nova-like outburst in January and a usual decline, a second outburst after one month, and a third weak one again a month later. Moreover a very small increase of the temperature at the beginning of April gives us a hint on a physical process with a period of one month. We obtained a BVRIc time sequence and modelled the photo

Dean-Yi Chou, Alexandr Serebryankiy

We study the solar-cycle variations of solar p-mode travel time for different wave packets to probe the magnetic fields at the base of the solar convection zone. We select the wave packets which return to the same spatial point after traveling around the Sun with integral number of bounces. The change in one-bounce travel time at solar maximum relative to mi

W. Bian, Y. Zhao

We assume that the gravitational instability of standard thin accretion disks leads to the Broad Line Regions (BLRs), the B band luminosity comes from standard thin disk and the motion of BLRs is virial. The central black hole masses, the accretion rates and the disk inclinations to the line of sight for 17 Seyfert 1 galaxies and 17 Palomar-Green (PG) quasar

Frederique Motte, Peter Schilke, Darek C. Lis

We have carried out a submillimeter continuum and spectroscopic study of the W43 main complex, a massive star-forming region, which harbors a giant HII region. The maps reveal a filamentary structure containing ~50 fragments with masses of 40-4000 Msun and typical diameters of 0.25 pc. Their large sizes, large non-thermal velocities (Dv ~ 5 km/s), and high d

Dan Hooper, Graham D. Kribs

In models in which all of the Standard Model fields live in extra universal dimensions, the lightest Kaluza-Klein (KK) particle can be stable. Calculations of the one-loop radiative corrections to the masses of the KK modes suggest that the identity of the lightest KK particle (LKP) is mostly the first KK excitation of the hypercharge gauge boson. This LKP i

F. Fang, T. Hojo

We report measurements of branching fractions for charged and neutral $B\to η_c K$ decays where the $η_c$ meson is reconstructed in the $K_S^0 K^{\pm}π^{\mp}, K^+ K^- π^0, K^{*0} K^-π^+$ and $p \bar{p}$ decay channels. The neutral $B^0$ channel is a CP eigenstate and can be used to measure the CP violation parameter $\sin 2ϕ_1$. We also report the first obse

Diego A. Wisniacki

The Loschmidt echo measures the sensitivity to perturbations of quantum evolutions. We study its short time decay in classically chaotic systems. Using perturbation theory and throwing out all correlation imposed by the initial state and the perturbation, we show that the characteristic time of this regime is well described by the inverse of the width of the

W. Melnitchouk

We explore the relationship between exclusive and inclusive electromagnetic scattering from the pion, focusing on the transition region at intermediate Q^2. Combining Drell-Yan data on the leading twist quark distribution in the pion with a model for the resonance region at large x, we calculate QCD moments of the pion structure function over a range of Q^2,

D. Markham, V. Vedral

We investigate the classical nature of the spin coherent states. In addition to being minimum uncertainty states, as the size of the spin, S, increases, the classical nature is seen to increase in two respects: in their resistance to entanglement generation (when passed through a beam splitter) and in the distinguishability of the states. In the infinite S l

Tomek Bartoszynski, Boaz Tsaban

We consider the question, which of the major classes defined by topological diagonalizations of open or Borel covers is hereditary. Many of the classes in the open case are not hereditary already in ZFC, and none of them is provably hereditary. This is contrasted with the Borel case, where some of the classes are provably hereditary. Two of the examples are

W. Selke, V. L. Pokrovsky, B. Buechner, T. Kroll

Motivated by recent experiments on cuprates with low-dimensional magnetic interactions, a new class of two-dimensional Ising models with short-range interactions and mobile defects is introduced and studied. The non-magnetic defects form lines, which, as temperature increases, first meander and then become unstable. Using Monte Carlo simulations and analytic

F. Krzakala, O. C. Martin

Using ground state computations, we study the transition from a spin glass to a ferromagnet in 3-d spin glasses when changing the mean value of the spin-spin interaction. We find good evidence for replica symmetry breaking up till the critical value where ferromagnetic ordering sets in, and no ferromagnetic spin glass phase. This phase diagram is in conflict

SLD Collaboration, Kenji Abe

We present an improved direct measurement of the parity-violation parameter A_b in the Z boson-b quark coupling using a self-calibrating track-charge technique applied to a sample enriched in Z -> b b-bar events via the topological reconstruction of the B hadron mass. Manipulation of the SLC electron-beam polarization permits the measurement of A_b to be mad

L. J. Kewley, M. J. Geller, R. A. Jansen, M. A. Dopita

We investigate the H-alpha and infrared star formation rate (SFR) diagnostics for galaxies in the Nearby Field Galaxy Survey (NFGS). For the 81 galaxies in our sample, we derive H-alpha fluxes (included here) from integrated spectra. There is a strong correlation between the ratio of far-infrared to optical luminosities L(FIR)/L(H-alpha) and the extinction E

Frank Krüger, Dmitri Melikhov

We analyse the form factors for the B --> gamma l^+l^- weak transition. We show that making use of the gauge invariance of the B --> gamma l^+l^- amplitude, the structure of the form factors in the resonance region, and their relations at large values of the photon energy results in efficient constraints on the behavior of the form factors. Based on these co

Ari Pankiewicz

We reconsider light-cone superstring field theory on the maximally supersymmetric pp-wave background. We find that the results for the fermionic Neumann matrices given so far in the literature are incomplete and verify our expressions by relating them to the bosonic Neumann matrices and proving several non-trivial consistency conditions among them, as for ex

C. Conti, S. Trillo

The process of optical frequency doubling can lead, in the undepleted regime, to the generation of a X-wave envelope with group velocity locked to the pump beam. Its parameters and its angular spectrum, are directly related to the zero- and first-order dispersive features of the nonlinear process. This constitutes a novel mechanism for spatio-temporal locali

H. de Riedmatten, I. Marcikic, W. Tittel, H. Zbinden

We report on a quantum interference experiment to probe the coherence between two photons coming from non degenerate photon pairs at telecom wavelength created in spatially separated sources. The two photons are mixed on a beam splitter and we observe a reduction of up to 84% in the coincidence count rate when the photons are made indistinguishable. This exp

D. A. Demir, M. Pospelov, A. Ritz

We re-examine questions concerning the contribution of the three-gluon Weinberg operator to the electric dipole moment of the neutron, and provide several QCD sum rule-based arguments that the result is smaller than - but nevertheless consistent with - estimates which invoke naive dimensional analysis. We also point out a regime of the MSSM parameter space w

Pushan Majumdar

Small expectation values are difficult to measure in Monte Carlo calculations as they tend to get swamped by noise. Recently an algorithm has been proposed by Luscher and Weisz which allows one to measure expectation values which previously could not be measured reliably in Monte Carlo simulations. We will test our implementation of this algorithm by looking

L. Del Debbio, H. Panagopoulos, E. Vicari

We study the dependence of the free energy on the CP violating angle theta, in four-dimensional SU(N) gauge theories with N >= 3, and in the large-N limit. Using the Wilson lattice formulation for numerical simulations, we compute the first few terms of the expansion of the ground-state energy F(theta) around theta = 0, F(theta) - F(0) = A_2 theta^2 (1 + b_2

G. Kofinas, E. Papantonopoulos, V. Zamarias

We extent our previous study on spherically symmetric braneworld solutions with induced gravity, including non-local bulk effects. We find the most general static four-dimensional black hole solutions with g_{tt}=-g_{rr}^{-1}. They satisfy a closed system of equations on the brane and represent the strong-gravity corrections to the Schwarzschild-(A)dS_4 spac

G. -J. van Zadelhoff, C. P. Dullemond, F. F. S. van der Tak, J. A. Yates

Comparison is made between a number of independent computer programs for radiative transfer in molecular rotational lines. The test models are spherically symmetric circumstellar envelopes with a given density and temperature profile. The first two test models have a simple power law density distribution, constant temperature and a fictive 2-level molecule,

Stephen C. Davis

In spacetimes of dimension greater than four it is natural to consider higher order (in R) corrections to the Einstein equations. In this letter generalized Israel junction conditions for a membrane in such a theory are derived. This is achieved by generalising the Gibbons-Hawking boundary term. The junction conditions are applied to simple brane world model

A. O. Petters

The standard treatment of gravitational lensing by a point mass lens M is based on a weak-field deflection angle a = 2/x, where x = (r c^2)/(2 G M) with r the distance of closest approach to the mass of a lensed light ray. It was shown that for a point mass lens, the total magnification and image centroid shift of a point source remain unchanged by relativis

Michal Kolář, František Slanina

We examine a model of biological evolution of Eigen's quasispecies in a holey fitness landscape, where the fitness of a site is either 0 (lethal site) or a uniform positive constant (viable site). So, the evolution dynamics is determined by the topology of the genome space. It is modeled by the random Bethe lattice. We use the effective medium and single

Ofer Biham, Azi Lipshtat

The recombination of hydrogen in the interstellar medium, taking place on surfaces of microscopic dust grains, is an essential process in the evolution of chemical complexity in interstellar clouds. The H_2 formation process has been studied theoretically, and in recent years also by laboratory experiments. The experimental results were analyzed using a rate

Kingman Cheung, Dilip Kumar Ghosh

The novel feature of a Higgs-triplet representation is a nonzero tree-level coupling of $H^+ W^- Z$, which is absent in all Higgs-doublet models. We study the associated production of a singly-charged Higgs boson of the Higgs-triplet representation with a $W$ or $Z$ boson at hadron colliders, followed by the $H^+ \to W^+ Z$ decay. We find that the $2\ell+4j$

S. Y. Liu, X. L. Lei

Momentum and energy balance equations are developed for steady-state electron transport and optical absorption under the influence of a dc electric field, an intense ac electric field of terahertz (THz) frequency in a two-dimensional (2D) semiconductor in the presence of a strong magnetic field perpendicular to the 2D plane. These equations are applied to st

Jay Gambetta, H. M. Wiseman

In this paper we present a perturbative procedure that allows one to numerically solve diffusive non-Markovian Stochastic Schrödinger equations, for a wide range of memory functions. To illustrate this procedure numerical results are presented for a classically driven two level atom immersed in a environment with a simple memory function. It is observed that

J. Burki, Raymond E. Goldstein, C. A. Stafford

When a macroscopic metallic wire is subject to tensile stress, it necks down smoothly as it elongates. We show that nanowires with radii comparable to the Fermi wavelength display remarkably different behavior. Using concepts from fluid dynamics, a PDE for nanowire shape evolution is derived from a semiclassical energy functional that includes electron-shell

Adrian Vasiu

We study a generalization of Serre--Tate theory of ordinary abelian varieties and their deformation spaces. This generalization deals with abelian varieties equipped with additional structures. The additional structures can be not only an action of a semisimple algebra and a polarization, but more generally the data given by some ``crystalline Hodge cycles&#

A. Ben-Kish, B. DeMarco, V. Meyer, M. Rowe

Using a single, harmonically trapped $^9$Be$^+$ ion, we experimentally demonstrate a technique for generation of arbitrary states of a two-level particle confined by a harmonic potential. Rather than engineering a single Hamiltonian that evolves the system to a desired final sate, we implement a technique that applies a sequence of simple operations to synth

B. DeMarco, A. Ben-Kish, D. Leibfried, V. Meyer

We report the experimental demonstration of a controlled-NOT (CNOT) quantum logic gate between motional and internal state qubits of a single ion where, as opposed to previously demonstrated gates, the conditional dynamics depends on the extent of the ion's wave-packet. Advantages of this CNOT gate over one demonstrated previously are its immunity from S

Dan Solomon

Dirac field theory is assumed to be gauge invariant. However it is well known that a calculation of the polarization tensor yields a non-gauge invariant result. The reason for this has been shown to be due to the fact that for Dirac theory to be gauge invariant there must be no lower bound to the free field energy. Here an additional proof will be presented

D. Salgado, J. L. Sanchez-Gomez

It is shown how the phase-damping master equation, either in Markovian and nonMarkovian regimes, can be obtained as an averaged random unitary evolution. This, apart from offering a common mathematical setup for both regimes, enables us to solve this equation in a straightforward manner just by solving the Schrodinger equation and taking the stochastic expec

D. Salgado, J. L. Sanchez-Gomez

It is shown how any Lindbladian evolution with selfadjoint Lindblad operators, either Markovian or nonMarkovian, can be understood as an averaged random unitary evolution. Both mathematical and physical consequences are analyzed. First a simple and fast method to solve this kind of master equations is suggested and particularly illustrated with the phase-dam

Ken-Ichi Aoki, Atsushi Horikoshi, Masaki Taniguchi, Haruhiko Terao

We analyze quantum mechanical systems using the non-perturbative renormalization group (NPRG). The NPRG method enables us to calculate quantum corrections systematically and is very effective for studying non-perturbative dynamics. We start with anharmonic oscillators and proceed to asymmetric double well potentials, supersymmetric quantum mechanics and many

Antonio Di Lisi, Klaus Moelmer

This paper presents simulations of the state vector dynamics for a pair of atomic samples which are being probed by phase shift measurements on an optical beam passing through both samples. We show how measurements, which are sensitive to different atomic components, serve to prepare states which are close to being maximally entangled.

F. M. C. Witte

In recent years methods have been proposed to extend classical game theory into the quantum domain. This paper explores further extensions of these ideas that may have a substantial potential for further research. Upon reformulating quantum game theory as a theory of classical games played by "quantum players" I take a constructive approach. The role

Bao-Sen Shi, Akihisa Tomita

In this paper, we give two very simple schemes to produce two kinds of W states, one kind is path W state with one photon and the other is multiphoton photon polarization W state. These schemes just need a common commercial multiport fiber coupler and single photon sources, they are feasible by current technologies.

Stephen D. Bartlett, David J. Rowe

We show that the classical mechanics of an algebraic model are implied by its quantizations. An algebraic model is defined, and the corresponding classical and quantum realizations are given in terms of a spectrum generating algebra. Classical equations of motion are then obtained by constraining the quantal dynamics of an algebraic model to an appropriate c

Christian Bracher, Tobias Kramer, Manfred Kleber

An alternative description of quantum scattering processes rests on inhomogeneous terms amended to the Schroedinger equation. We detail the structure of sources that give rise to multipole scattering waves of definite angular momentum, and introduce pointlike multipole sources as their limiting case. Partial wave theory is recovered for freely propagating pa

Felix Naef, Marcelo O. Magnasco

HDONA technology is predicated on two ideas. First, the differential between high-affinity (perfect match, PM) and lower-affinity (mismatch, MM) probes is used to minimize cross-hybridization. Second, several short probes along the transcript are combined, introducing redundancy. Both ideas have shown problems in practice: MMs are often brighter than PMs, an

D. E. Kahana, S. H. Kahana

The inclusive spectra so far accumulated at the Relativistic Heavy Ion Collider (RHIC) at energies of $\sqrt{s} = 56, 130$ and 200 GeV are examined within the hadronic simulation LUCIFER. What emerges at this juncture is a comprehensive and clear picture of soft physics which apparently dominates the intermediate and later stages of the ion collisions. The f

C. E. Vargas, J. G. Hirsch, J. P. Draayer

Normal parity bands are studied in 157Gd, 163Dy and 169Tm using the pseudo SU(3) shell model. Energies and B(E2) transition strengths of states belonging to six low-lying rotational bands with the same parity in each nuclei are presented. The pseudo SU(3) basis includes states with pseudo-spin 0 and 1, and 1/2 and 3/2, for even and odd number of nucleons, re

Wojciech Florkowski, Wojciech Broniowski

We show that the transverse-momentum spectra of all hadrons measured at RHIC, including hyperons, are described very well in a thermal model assuming the simultaneous chemical and thermal freeze-outs. The model calculation takes into account all hadronic resonances and uses a simple parametrization of the freeze-out hypersurface.

Andrey A. Sukhorukov, Nail N. Akhmediev

We propose new planar X-junctions and multi-port devices written by spatial solitons, which are composed of two (or more) nonlinearly coupled components in Kerr-type media. Such devices have no radiation losses at a given wavelength. We demonstrate that, for the same relative angle between the channels of the X-junctions, one can vary the transmission coeffi

Daisuke Yoshihara, Fumitaka Yura, Tetsuji Tokihiro

We investigate a soliton cellular automaton (Box-Ball system) with periodic boundary conditions. Since the cellular automaton is a deterministic dynamical system that takes only a finite number of states, it will exhibit periodic motion. We determine its fundamental cycle for a given initial state.

C. P. Hughes, Z. Rudnick

We consider a smooth counting function of the scaled zeros of the Riemann zeta function, around height T. We show that the first few moments tend to the Gaussian moments, with the exact number depending on the statistic considered.

Ernie Croot

For completely multiplicative functions f(n) taking values 1 and -1, under certain conditions on f(n) we show that f(n) changes sign at least x exp(-7(log log x)sqrt(log x)) times as n runs through the integers <= x.

Nuno Franco, Juan Gonzalez-Meneses

We present a new algorithm to solve the conjugacy problem in Artin braid groups, which is faster than the one presented by Birman, Ko and Lee. This algorithm can be applied not only to braid groups, but to all Garside groups (which include finite type Artin groups and torus knot groups among others).

Marcus Pivato

If M is a monoid (e.g. the lattice Z^D), and G is a finite (nonabelian) group, then G^M is a compact group; a `multiplicative cellular automaton&#39; (MCA) is a continuous transformation F:G^M-->G^M which commutes with all shift maps, and where nearby coordinates are combined using the multiplication operation of G. We characterize when MCA are group endomor

O. B. Zaslavskii

Recently we showed that in semiclassical 2D dilaton gravity the regularity of a black hole horizon may be compatible with divergencies of Polyakov-Liouville stresses on it, the temperature deviating from its Hawking value. This makes the question about thermal properties of such solutions non-trivial. We demonstrate that, adding to gravitation-dilaton part o

Maja Buric, Voja Radovanovic

In this paper we calculate the divergent part of the one loop effective action for QED on noncommutative space using the background field method. The effective action is obtained up to the second order in the noncommutative parameter theta and in the classical fields.

Sunil Mukhi, Nemani V. Suryanarayana

In the limit of large, constant B-field (the ``Seiberg-Witten limit&#39;&#39;), the derivative expansion for open-superstring effective actions is naturally expressed in terms of the symmetric products *n. Here, we investigate corrections around the large-B limit, for Chern-Simons couplings on the brane and to quadratic order in gauge fields. We perform a bo

Artur B. Adib

Derrick&#39;s theorem on the nonexistence of stable time-independent scalar field configurations [G. H. Derrick, J. Math. Phys. 5, 1252 (1964)] is generalized to finite systems of arbitrary dimension. It is shown that the &#34;dilation&#34; argument underlying the theorem hinges upon the fulfillment of specific Neumann boundary conditions, providing thus new

Andrei Afanasev, Igor Akushevich, N. P. Merenkov

We calculated two--photon exchange effects for elastic electron--proton scattering at high momentum transfers. The corresponding nucleon Compton amplitude is defined by two space--like virtual photons that appear to have significant virtualities. We make predictions for a) a single--spin beam asymmetry, and b) a single--spin target asymmetry or recoil proton

Johann Rafelski

We relate the reported variation in the value of the fine structure constant to a possible non-universality of the gravitational interaction with respect to different particle generations.

I. V. Andreev

Modification of the particles in the course of the source evolution is considered. Influence of this effect on multiplicities and correlations of the particles is displayed, including an enhancement of the production rates and identical particle correlations and also back-to-back particle-antiparticle correlations.

Maarten Golterman, Elisabetta Pallante

Recently, we pointed out that chiral transformation properties of penguin operators change in the transition from unquenched to (partially) quenched QCD. As a consequence, new operators appear in (partially) quenched QCD penguins, introducing ambiguities which should be considered a quenching artifact. Here we discuss more specifically the effects of this ph

J. Kotanski, J. Wosiek

New results obtained within the recently developed approach to supersymmetric quantum mechanical systems are presented. The method does not suffer from the sign problem in any dimensions and is capable to provide any quantum observable with controllable systematic error. Discussed results include: the spectrum and Witten index of the D=4 system, and the spec

Ting-Wai Chiu, Tung-Han Hsieh

We examine quenched chiral logarithms in lattice QCD with overlap Dirac quarks. From our data of m_pi^2, we determine the coefficient of quenched chiral logarithm delta = 0.203(14), 0.176(17), 0.193(17) and 0.200(13) for lattices of sizes 8^3 times 24, 10^3 times 24, 12^3 times 24 and 16^3 times 32 respectively. Also, for the first three lattice sizes, we me

A. C. Irving, UKQCD Collaboration

We present preliminary results from UKQCD simulations at light quark masses using two flavours of non-pertubatively improved Wilson fermions. We report on the performance of the standard HMC algorithm at these quark masses where m_pi/m_rho < 0.5 in comparison with simulations using improved staggered quarks.

F. Farchioni, C. Gebert, I. Montvay, L. Scorzato

The numerical simulation of domain wall quarks with the two-step multi-boson (TSMB) algorithm is investigated. Tests are performed on a 8^3*4 lattice with N_f=2 quark flavours.

J. Engelfried, I. S Filimonov, J. Kilmer, A. P. Kozhevnikov

SELEX took data in the 1996/7 Fixed Target Run at Fermilab. The excellent performance parameters of the SELEX RICH Detector had direct influence on the quality of the obtained physics results.

Andre G. Holzner

One of the missions of the LEP program was the search for the Standard Model Higgs Boson. The skillful operation of the machine in the year 2000, the final year of operation, has allowed the four collaborations ALEPH, DELPHI, L3 and OPAL to collect 536/pb of data at center-of-mass energies of 206 GeV or higher. This data is used to probe the existence of the

J. L. Jaramillo, V. Aldaya

We present a model for introducing dynamics into a space-time geometry. This space-time structure is constructed from a C*-algebra defined in terms of the generators of an irreducible unitary representation of a finite-dimensional Lie algebra G. This algebra is included as a subalgebra in a bigger algebra F, the generators of which mix the representations of

C. Bona, T. Ledvinka, C. Palenzuela

A suite of three evolution systems is presented in the framework of the 3+1 formalism. The first one is of second order in space derivatives and has the same causal structure of the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) system for a suitable choice of parameters. The second one is the standard first order version of the first one and has the same causal

Claudio Simeone

A consisten quantization with a clear notion of time and evolution is given for the anisotropic Kantowski-SDachs cosmological model. It is shown that a suitable coordinate choice allows to obtain a solution of the Wheeler-DeWitt equation in the form of definite energy states, and that the results can be associated to two disjoint equivalent theories, one for

F. S. de Boer, M. Gabbrielli, M. C. Meo

A temporal logic is presented for reasoning about the correctness of timed concurrent constraint programs. The logic is based on modalities which allow one to specify what a process produces as a reaction to what its environment inputs. These modalities provide an assumption/commitment style of specification which allows a sound and complete compositional ax

P. S. Cornaglia, C. A. Balseiro

We present results for the spectral properties of Kondo impurities in nanoscopic systems. Using Wilson&#39;s renormalization group we analyze the frequency and temperature dependence of the impurity spectral density for impurities in small systems that are either isolated or in contact with a reservoir. We have performed a detailed analysis of the structure

V. R. Shaginyan

We show that the quasiparticle effective mass $M^*$ diverges as a function of the system&#39;s density $x$, $M^*\propto 1/(x-x_{FC})$, when a system approaches the critical point $x_{FC}$ at which the fermion condensation quantum phase transition (FCQPT) occurs. Such behavior is of general form and takes place in both three dimensional systems and two dimens

B. Jackson, E. Zaremba

We discuss the collective modes in a harmonically trapped, highly-elongated Bose condensed gas. The transverse breathing mode exhibits a number of interesting features, such as the insensitivity of the condensate mode frequency to the interaction strength, and the closeness of the frequency to that of the non-condensed thermal cloud in the collisionless limi

Claudia Pombo, Armen E. Allahverdyan, Theo M. Nieuwenhuizen

The spin-boson model, often used in NMR and ESR physics, quantum optics and spintronics, is considered in a solvable limit to model a spin one-half particle interacting with a bosonic thermal bath. By applying external pulses to a non-equilibrium initial state of the spin, work can be extracted from the thermalized bath. It occurs on the timescale T_2 inhere

Theo M. Nieuwenhuizen, Armen E. Allahverdyan

The Brownian motion of a harmonically bound quantum particle and coupled to a harmonic quantum bath is exactly solvable. At low enough temperatures the stationary state is non-Gibbsian due to an entanglement with the bath. This happens when a cloud of bath modes around the particle is formed. Equilibrium thermodynamics for particle plus bath together, does n

Armen E. Allahverdyan, Roger Balian, Theo M. Nieuwenhuizen

Thomson&#39;s formulation of the second law - no work can be extracted from a system coupled to a bath through a cyclic process - is believed to be a fundamental principle of nature. For the equilibrium situation a simple proof is presented, valid for macroscopic sources of work. Thomson&#39;s formulation gets limited when the source of work is mesoscopic, i

A. D. Speliotopoulos

The kinetic part of the Rasetti-Regge action I_{RR} for vortex lines is studied and links to string theory are made. It is shown that both I_{RR} and the Polyakov string action I_{Pol} can be constructed with the same field X^mu. Unlike I_{NG}, however, I_{RR} describes a Schwarz-type topological quantum field theory. Using generators of classical Lie algebr

M. Krawiec, K. I. Wysokinski

The quantum dot asymmetrically coupled to the external leads has been analysed theoretically by means of the equation of motion (EOM) technique and the non-crossing approximation (NCA). The system has been described by the single impurity Anderson model. To calculate the conductance across the device the non-equilibrium Green&#39;s function technique has bee

M. S. Laad, E. Müller-Hartmann

Based on a comprehensive perusal of experimental results, we construct a microscopic model describing the normal state of layered 4d oxide Sr_2 RuO_4 incorporating relevant quantum chemical features of the material. The high-T anomalies are explained within a Luttinger liquid (LL) picture. Interlayer one-particle hopping drives a dimensional crossover to a c

W. A. M. Morgado

In the present work, we study qualitatively the physics of granular temperature coexistence, for a mixture of two different species. Our model captures its essential aspects and this allows us to get insights on the physical mechanisms of distinct temperature coexistence, in a way which is not obscured by the complexities of kinetic theories or numerical sim

P. M. C de Oliveira, S. Moss de Oliveira

We introduce into the Penna Model for biological ageing one of the possible male mechanisms used to maximize the ability of their sperm to compete with sperm from other males. Such a selfish mechanism increases the male reproduction success but may decrease the survival probability of the whole female population, depending on how it acts. We also find a dyna

J. B. Philipp, L. Alff, A. Marx, R. Gross

We have performed a systematic analysis of the low frequency 1/f-noise in single grain boundary junctions in the colossal magnetoresistance material La_{2/3}Ca_{1/3}MnO_{3-delta}. The grain boundary junctions were formed in epitaxial La_{2/3}Ca_{1/3}MnO_{3-delta} films deposited on SrTiO_3 bicrystal substrates and show a large tunneling magnetoresistance of

G. E. Volovik

We discuss the structure of a vortex in a superfluid Bose liquid with a suppressed Bose-Einstein condensate and an intensive pair correlated condensate. The vortex represents the pair of half-quantum vortices topologically confined by the soliton.

W. Apel, H. -U. Everts, U. Koerner

The quasi-particle weight of a single hole in an antiferromagnetic background is studied in the semiclassical approximation. We start from the t-J model, generalize it to arbitrary spin S by employing an appropriate coherent state representation for the hole, and derive an effective action for the dynamics in the long-wavelength low-energy limit. In the same

Marc Barthelemy, Bernard Gondran, Eric Guichard

The Internet infrastructure is not virtual: its distribution is dictated by social, geographical, economical, or political constraints. However, the infrastructure&#39;s design does not determine entirely the information traffic and different sources of complexity such as the intrinsic heterogeneity of the network or human practices have to be taken into acc

Gabor Szabo, Mikko Alava, Janos Kertesz

Real growing networks like the WWW or personal connection based networks are characterized by a high degree of clustering, in addition to the small-world property and the absence of a characteristic scale. Appropriate modifications of the (Barabasi-Albert) preferential attachment network growth capture all these aspects. We present a scaling theory to descri

M. Grifoni, M. S. Ferreira, J. Peguiron, J. B. Majer

We investigate directed motion in non-adiabatically rocked ratchet systems sustaining few bands below the barrier. Upon restricting the dynamics to the lowest M bands, the total system-plus-bath Hamiltonian is mapped onto a discrete tight-binding model containing all the information both on the intra- and inter-well tunneling motion. A closed form for the cu

Dmitri S. Golubev, Gerd Schön, Andrei D. Zaikin

We investigate low-temperature dephasing in several model systems, where a quantum degree of freedom is coupled to a bath. Dephasing, defined as the decay of the coherence of inital non-equilibrium states, also influences the dynamics of equilibrium correlation and response functions, as well as static interference effects. In particular in the latter case d

I. A. Nekrasov, Z. V. Pchelkina, G. Keller, Th. Pruschke

LiV_2 O_4 is one of the most puzzling compounds among transition metal oxides because of its heavy fermion like behavior at low temperatures. In this paper we present results for the orbital state and magnetic properties of LiV_2 O_4 obtained from a combination of density functional theory within the local density approximation and dynamical mean-field theor

Alexander K. Hartmann, Alan J. Bray, A. C. Carter, M. A. Moore

We study the scaling behavior of domain-wall energies in two-dimensional Ising spin glasses with Gaussian and bimodal distributions of the interactions and different types of boundary conditions. The domain walls are generated by changing the boundary conditions at T=0 in one direction. The ground states of the original and perturbed system are calculated nu

D. van der Marel, A. J. Leggett, J. W. Loram, J. R. Kirtley

From an analysis of the specific heat of one of the cuprate superconductors it is shown, that even if a large part of the experimental specific heat associated with the superconducting phase transition is due to fluctuations, this part must be counted when one tries to extract the condensation energy from the data. Previous work by Chakravarty, Kee and Abrah

N. Abed-Pour, A. Aghamohammadi, M. Khorrami, M. Reza Rahimi Tabar

It is known that discrete scale invariance leads to log-periodic corrections to scaling. We investigate the correlations of a system with discrete scale symmetry, discuss in detail possible extension of this symmetry such as translation and inversion, and find general forms for correlation functions.

A. L. Chernyshev, R. F. Wood

In this short review article, we consider some aspects of the spin-polaron concept as they relate to high-Tc superconductivity. The article is intended to be an overview in which a flavor of the research on spin polarons is given.

Scott H. Clearwater, Stephen D. Kleban

We show that the distribution of supercomputer job submission interarrival times can be understood as a relaxation process. The process of deciding when to submit a job involves a complicated set of interactions between the users themselves, the queuing algorithm, the supercomputer, and a hierarchy of other decision makers. This is analogous to the hierarchi

A. P. C. Malbouisson, J. M. C. Malbouisson, A. E. Santana

By considering the Ginzburg-Landau model, compactified in one of the spatial dimensions, and using a modified Matsubara formalism, we determine the dependence of the superconducting transition temperature (T_c) of a film as a function of its thickness (L). We show that T_c is a decreasing linear function of L^{-1}, as has been found experimentally. The criti

A. O. Govorov, A. V. Kalameitsev, V. M. Kovalev

We develop a quantum theory of the nonlinear interaction between intense surface acoustic waves and electrons of a quantum well in the regime of moving quantum wires and dots. The quantum nonlinear interaction qualitatively differs from the classical one. In a system of electron wires driven by an acoustic wave the sound attenuation strongly decreases with i

Alon Retter, Timothy R. Bedding, Derek Buzasi, Hans Kjeldsen

Observations of the red giant Arcturus (Alpha Boo) obtained with the star tracker on the Wide Field Infrared Explorer (WIRE) satellite during a baseline of 19 successive days in 2000 July-August are analysed. The power spectrum has a significant excess of power at low-frequencies. The highest peak is at about 4.1 micro-Hz, which is in agreement with the grou

D. Proga, M. C. Begelman

We report on the first phase of our study of slightly rotating accretion flows onto black holes. We consider inviscid accretion flows with a spherically symmetric density distribution at the outer boundary, but with spherical symmetry broken by the introduction of a small, latitude-dependent angular momentum. We study accretion flows by means of numerical 2D

N. C. Sterling, H. L. Dinerstein, C. W. Bowers

We report the discovery of Ge III $λ$1088.46 in the planetary nebulae (PNe) SwSt 1, BD+30$^{\rm o}$3639, NGC 3132, and IC 4593, observed with the Far Ultraviolet Spectroscopic Explorer. This is the first astronomical detection of this line and the first measurement of Ge (Z = 32) in PNe. We estimate Ge abundances using S and Fe as reference elements, for a r