May 2003 arXiv papers — page 19

Paolo Coppola, Simone Martini

We present a type inference algorithm for lambda-terms in Elementary Affine Logic using linear constraints. We prove that the algorithm is correct and complete.

Yang Li, Weiping Gou, Ji Chi, Joseph H. Ross

Cu-doped type-I germanium clathrate can exhibit dilute magnetism, including ferromagnetism, antiferromagnetism, and metamagnetic transitions up to 90 K. 63Cu NMR measurements confirm that these transitions are due to a dilute composition of magnetic defects coupled by conduction electrons, behavior similar to that of magnetic semiconductors. Magnetic measure

L. M. Abreu, A. P. C. Malbouisson, I. Roditi

We investigate the minimal size of small superconducting grains by means of a Ginzburg-Landau model confined to a sphere of radius $R$. This model is supposed to describe a material in the form of a ball, whose transition temperature when presented in bulk form, $T_{0}$, is known. We obtain an equation for the critical temperature as a function of $R$ and of

Nathan Salwen, Steven A. Sheets, Stephen R. Cotanch

We extend previous studies of the BCS canonical approach for the attractive Hubbard model. A derivation of the BCS formulation is presented for both the Hubbard and a simpler reduced Hamiltonian. Using direct diagonalization, exact one and two dimensional solutions for both Hamiltonians are compared to BCS variational calculations. Approximate and exact grou

L. M. Abreu, A. P. C. Malbouisson, I. Roditi

In this paper we consider a superconducting film modeled by the Ginzburg-Landau model, confined between two parallel planes a distance $L$ apart from one another. Our approach is based on the Gaussian effective potential in the transverse unitarity gauge, which allows to treat gauge contributions in a compact form. Using techniques from dimensional and $zeta

M. Nauenberg

In this note it is shown that in his ``Comments'', Tsallis did not point out any flaws in the main criticism of my paper, namely, that the nonextensive q-entropy formalism fails to satisfy the zeroth law of thermodynamics. Details are also given of a rigorous thermodynamic proof which demonstrates that, contrary to Tsallis's assertion, the applic

Damir Herman, Harsh Mathur, Ganpathy Murthy

Recently, new strongly interacting phases have been uncovered in mesoscopic systems with chaotic scattering at the boundaries by two of the present authors and R. Shankar. This analysis is reliable when the dimensionless conductance of the system is large, and is nonperturbative in both disorder and interactions. The new phases are the mesoscopic analogue of

Dominique Gobert, Ulrich Schollwock, Jan von Delft

We investigate the Josephson effect between two coupled superconductors, coupled by the tunneling of pairs of electrons, in the regime that their energy level spacing is comparable to the bulk superconducting gap, but neglecting any charging effects. In this regime, BCS theory is not valid, and the notion of a superconducting order parameter with a well-defi

A. Maciolek, M. Krech, S. Dietrich

A lattice model of 3He - 4He mixtures which takes into account the continuous rotational symmetry O(2) of the superfluid degrees of freedom of 4He is studied in the molecular-field approximation and by Monte Carlo simulations in three dimensions. In contrast to its two-dimensional version, for reasonable values of the interaction parameters the resulting pha

S. Syed, M. J. Manfra, Y. J. Wang, H. L. Stormer

Cyclotron-resonance (CR) measurements on two-dimensional (2D) electrons in AlGaN/GaN heterojunctions reveal large splittings (up to 2 meV) of the CR line for all investigated densities, $n_{2D}$, from 1 to $4\times 10^{12}cm^{-2}$ over wide ranges of magnetic field. The features resemble a level anti-crossing and imply a strong interaction with an unknown ex

C. Goujon, N. Thomas, B. Dalloz-Dubrujeaud

Recent studies have pointed out the importance of the basal friction on the dynamics of granular flows. We present experimental results on the influence of the roughness of the inclined plane on the dynamics of a monodisperse dry granular flow. We found experimentally that it exists a maximum of the friction for a given relative roughness. This maximum is sh

Arne Soulier, Tim Halpin-Healy

We examine kinetic symmetry breaking phenomena in an evolutionary political game in which voters, inhabiting a multidimensional ideological space, cast ballots via selection mechanisms subject to the competing forces of conformity and dissent. Our understanding of the spatiotemporally complex population dynamics is informed by a system of nonlinear replicato

S. I. Denisov, E. S. Denisova

We study the equilibrium, oscillatory and transport properties of a chain of charged particles which interact with each other via the Coulomb and power-like repulsive interactions. Exact, analytical expressions for the energy of the ground state, interparticle distances, and vibration spectrum are derived, and the stability criterion for a chain with equidis

Theo Odijk

Several controversial issues concerning the packing of linear DNA in bacteriophages and globules are discussed. Exact relations for the osmotic pressure, capsid pressure and loading force are derived in terms of the hole size inside phages under the assumption that the DNA globule has a uniform density. A new electrostatic model is introduced for computing t

Sanjeev Kumar, Pinaki Majumdar

We solve the double exchange model in the presence of arbitrary substitutional disorder by using a self consistently generated effective Hamiltonian for the spin degrees of freedom. The magnetic properties are studied through classical Monte Carlo while the effective exchange, $D_{ij}$, are calculated by solving the disordered fermion problem, and renormalis

M. Turek, W. John

We study the localization length of a pair of two attractively bound particles moving in a one-dimensional random potential. We show in which way it depends on the interaction potential between the constituents of this composite particle. For a pair with many bound states N the localization length is proportional to N, independently of the form of the two pa

F. K. Wilhelm, M. J. Storcz, C. H. van der Wal, C. J. P. M. Harmans

On the way to solid-state quantum computing, overcoming decoherence is the central issue. In this contribution, we discuss the modeling of decoherence of a superonducting flux qubit coupled to dissipative electronic circuitry. We discuss its impact on single qubit decoherence rates and on the performance of two-qubit gates. These results can be used for desi

Lucia Comez, Daniele Fioretto, Filippo Scarponi, Giulio Monaco

Brillouin scattering has been used to measure the dynamic structure factor of glycerol as a function of temperature from the high temperature liquid to the glassy state. Our investigation aims at understanding the number and the nature of the relaxation processes active in this prototype glass forming system in the high frequency region. The associated chara

J. M. P. Carmelo

In this paper we describe the pseudoparticles, holons, and spinons whose occupancy configurations describe the energy eigenstates of the one-dimensional (1D) Hubbard model in terms of rotated electrons. Rotated electrons are related to electrons by a mere unitary transformation such that rotated electron double occupation is a good quantum number. Moreover,

E. S. Denisova

A statistical theory of the strip domain structure excited in a bubble film by an oscillating magnetic field is developed. The theory is based on the consideration of the strip domain structure as a thermodynamic system characterized by the spectrum of domain walls oscillation and an effective temperature that is caused by an oscillating magnetic field and f

G. Fratesi, G. P. Brivio, L. G. Molinari

A method to implement the many-body Green function formalism in the GW approximation for infinite non periodic systems is presented. It is suitable to treat systems of known ``asymptotic'' properties which enter as boundary conditions, while the effects of the lower symmetry are restricted to regions of finite volume. For example, it can be applied t

S. I. Denisov, T. V. Lyutyy, K. N. Trohidou

We study the slow phase of thermally activated magnetic relaxation in finite two-dimensional ensembles of dipolar interacting ferromagnetic nanoparticles whose easy axes of magnetization are perpendicular to the distribution plane. We develop a method to numerically simulate the magnetic relaxation for the case that the smallest heights of the potential barr

Ajit Kumar Mahapatro, Subhasis Ghosh

We have investigated the charge carrier transport in organic molecular semiconductors. It has been found that mobility is a function of electric field and temperature due to hopping conduction. Several theoretical models for charge transport in disordered solids have been debated over the role of spatial and energetic correlation in these systems and such co

Georg Goeppert, Hermann Grabert

We study a spin S=M/2--Kondo system coupled to electrons in an arbitrary nonequilibrium situation above Kondo temperature. Coupling to hot electrons leads to an increased inverse lifetime of pseudo particles, related to the Korringa width. This in turn is responsible for the increased inelastic relaxation rates of the electronic system. The rates are related

E. Abad, Jonathan L. Bentz, G. Nicolis, John J. Kozak

An analytical method based on the classical ruin problem is developed to compute the mean reaction time between two walkers undergoing a generalized random walk on a 1d lattice. At each time step, either both walkers diffuse simultaneously with probability $p$ (synchronous event) or one of them diffuses while the other remains immobile with complementary pro

M. Tomellini, M. Fanfoni

It has been shown that the KJMA (Kolmogorov-Johnson-Mehl-Avrami) solution of phase transition kinetics can be set as a problem of correlated nucleation [Phys.Rev.B65, 172301 (2002)]. In this paper the equivalence between the standard solution and the approach that makes use of the actual nucleation rate, i.e. that takes into account spatial correlation among

S. V. Dubonos, V. I. Kuznetsov, A. V. Nikulov

A theoretical prediction published in Phys.Rev. B 64, 012505 (2001) is corroborated experimentally. This corroboration of the theoretical result published in Physical Review B was rejected for publication in the same journal. Such inconsistency is connected with a contradiction to the second law of thermodynamics. According to the theory Phys.Rev. B 64, 0125

R. Zitko, J. Bonca

We develop a non-perturbative numerical method to study tunneling of a single electron through an Aharonov-Bohm ring where several strongly interacting electrons are bound. Inelastic processes and spin-flip scattering are taken into account. The method is applied to study microscopic mechanisms of dephasing in a non-trivial model. We show that electron-elect

Pierre-Gilles de Gennes, Ko Okumura

Single crystal nematic elastomers undergo a transition from a strongly ordered phase N to an "isotropic" phase I. We show that: (a) samples produced under tension by the Finkelmann procedure are intrinsically anisotropic and should show a small (temperature dependent) birefringence in the high temperature I phase. (b) for the I->Ntransition via cooli

A. Buzdin, M. Daumens

We propose an exactly solvable model to describe the properties of atomic thickness hybrid ferromagnet-superconductor-ferromagnet (F/S/F) structures. We show that the superconducting critical temperature is always higher for antiparallel orientation of the ferromagnetic moments. However at low temperature the superconducting gap occurs to be larger for paral

Alexander Albus, Fabrizio Illuminati, Jens Eisert

We discuss the theory of mixtures of Bosonic and Fermionic atoms in periodic potentials at zero temperature. We derive a general Bose--Fermi Hubbard Hamiltonian in a one--dimensional optical lattice with a superimposed harmonic trapping potential. We study the conditions for linear stability of the mixture and derive a mean field criterion for the onset of a

Miguel A. Munoz

Stochastic phenomena in which the noise amplitude is proportional to the fluctuating variable itself, usually called {\it multiplicative noise}, appear ubiquitously in physics, biology, economy and social sciences. The properties of spatially extended systems with this type of stochasticity, paying special attention to the {\it non-equilibrium phase transiti

Eduardo L. Martin

Adaptive optics corrected images obtained with the CIAO instrument at the Subaru 8.2-meter telescope show the presence of two subarsecond companions to the nearby (d=19.3 pc) young star GJ 900, which was previously classified as a single member of the IC 2391 supercluster. The two companions share the same proper motion as the primary and are redder. Their p

Dmitri A. Uzdensky

We investigate the axisymmetric magnetosphere of an aligned rotating magnetic dipole surrounded by an ideal force-free plasma. We concentrate on the magnetic field structure around the point of intersection of the separatrix between the open and closed field-line regions and the equatorial plane. We first study the case where this intersection point is locat

J. Wang, T. Yaqoob, G. Szokoly, R. Gilli

In this letter we report the detection of an extremely strong X-ray emission line in the 940ks chandra ACIS-I spectrum of CXO CDFS J033225.3-274219. The source was identified as a Type1 AGN at redshift of z = 1.617, with 2.0 -- 10.0 keV rest frame X-ray luminosity of ~ 10^44 ergs s^-1. The emission line was detected at 6.2^{+0.2}_{-0.1} keV, with an equivale

E. Bugaev, T. Montaruli, I. Sokalski

If neutrinos produced in astrophysics sources oscillate, neutrino telescopes can have a chance to detect signals from tau-neutrinos. We present an estimate of the 'double bang' event rate produced by tau neutrinos in cubic kilometer scale detectors.

Pasi Hakala, Gavin Ramsay, Kinwah Wu, Linnea Hjalmarsdotter

RX J0806+15 has recently been identified as the binary system with the shortest known orbital period. We present a series of observations of RX J0806+15 including new optical observations taken one month apart. Using these observations and archival data we find that the period of this system is decreasing over time. Our measurements imply f_dot = 6.11x10^-16

J. P. U. Fynbo, C. Ledoux, P. Moller, B. Thomsen

We present the first results of an observational programme at the ESO Very Large Telescope aimed at detecting a large sample of high-redshift galaxies fainter than the current spectroscopic limit of R=25.5 for Lyman-Break galaxies. In this paper, we describe the results of deep narrow and broad-band imaging and subsequent follow-up multi-object spectroscopy

Roger Hildebrand

Polarimetry in the far-infrared and submillimeter has been valuable in tracing magnetic fields in bright Galactic Clouds. We discuss the techniques we have developed and trends we have found in polarization vs column density, and vs wavelength. The polarization spectrum has proven to be more interesting than had been anticipated. It is potentially valuable i

Edward F. Guinan, Ignasi Ribas, Graham M. Harper

We present and analyze FUSE observations of six solar analogs. These are single, main-sequence G0-5 strs selected as proxies for the Sun at several stages of its main-sequence lifetime. The emission features in the FUSE 920-1180 A wavelength range allow for a critical probe of the hot plasma over three decades in temperature. Using the flux ratio CIII 1176/9

A. Georgakakis, I. Georgantopoulos, G. C. Stewart, T. Shanks

This paper explores the X-ray properties of `normal' galaxies using a shallow XMM-Newton survey covering an area of ~1.5deg2. The X-ray survey overlaps with the 2dF Galaxy Redshift Survey. Compared with previous studies this has the advantage of high quality spectra and spectral classifications to bj=19.4. Moreover, sources with optical spectra revealing

Adam Burrows, David Sudarsky, William B. Hubbard

Using a full frequency-dependent atmosphere code that can incorporate irradiation by a central primary star, we calculate self-consistent boundary conditions for the evolution of the radius of the transiting planet HD 209458b. Using a well-tested extrasolar giant planet evolutionary code, we then calculate the behavior of this planet's radius with age. T

M. Dall'Ora, G. Bono, J. Storm, V. Testa

We present near-infrared (JKs) time series data of the Large Magellanic Cloud (LMC) cluster Reticulum. The observing strategy and data reduction (DAOPHOTII/ALLFRAME) allowed us to reach a photometry accuracy of the order of 0.02 mag at limiting magnitudes typical of RR Lyrae stars. We are interested in Reticulum, since it hosts a sizable sample of RR Lyrae (

R. P. Duperray, C. -Y. Huang, K. V. Protasov, M. Buenerd

A new parameterization of the antiproton inclusive production cross section in proton-proton and proton-nucleus collisions is proposed. A sample of consistent pA->pbar X$ experimental data sets measured on 1<A<208 nuclei, from 12 GeV up to 400 GeV incident energy, have been used to constrain the parameters. A broader energy domain is covered for the pp->pbar

Y. A. Shibanov, A. B. Koptsevich, J. Sollerman, P. Lundqvist

We report on the first detection of the Vela pulsar in the near-infrared with the VLT/ISAAC in the Js and H bands. The pulsar magnitudes are Js=22.71 +/- 0.10 and H=22.04 +/- 0.16. We compare our results with the available multiwavelength data and show that the dereddened phase-averaged optical spectrum of the pulsar can be fitted with a power law F_nu propt

Matias Zaldarriaga

We summarize the physical mechanism by which the Cosmic Microwave Background acquires a small degree of polarization. We discuss the imprint left by gravitational waves and the use of polarization as a test of the inflationary paradigm. We discuss some physical processes that affect the CMB polarization after recombination such as gravitational lensing and t

P. Borde, G. Perrin, A. Amy-Klein, C. Daussy

The detection of terrestrial planets by Darwin/TPF missions will require extremely high quality wavefronts. Single-mode fibers have proven to be powerful beam cleaning components in the near-infrared, but are currently not available in the mid-infrared where they would be critically needed for Darwin/TPF. In this paper, we present updated measurements on the

S. Araujo-Betancor, B. T. Gaensicke, H. -J. Hagen, P. Rodriguez-Gil

We report the identification of the cataclysmic variable 1RXSJ062518.2+733433 as an intermediate polar. The orbital period of the system is determined to be 283.0+-2 min from the radial velocity variation of Halpha, measured in an extensive set of time-resolved spectroscopy. Differential optical photometry obtained over a base line of three weeks reveals the

Sara L. Ellison, Max Pettini, Chris W. Churchill, Isobel M. Hook

We present a brief overview of the ongoing Complete Optical and Radio Absorption Line System (CORALS) survey. We review the results of our survey for z>2.2 damped Lyman alpha systems (DLAs) and present the preliminary results of an extended survey to lower redshifts (0.7<z<1.5). Although final observations are still pending, our preliminary statistics do not

T. J. Turner, S. B. Kraemer, R. F. Mushotzky, I. M. George

We present RGS data from an XMM-Newton observation of the Seyfert 1 galaxy NGC 3516, taken while the continuum source was in an extreme low state. The spectrum shows numerous emission lines including the H-like lines of C, N and O and the He-like lines of N, O and Ne. These data show that the N lines are far stronger than would be expected from gas of solar

R. T. Edwards, B. W. Stappers

We report the detection of pulse-to-pulse periodic intensity modulations, in observations of recycled pulsars. Even though the detection of individual pulses was generally not possible due to their low flux density and short duration, through the accumulation of statistics over sequences of 10^5--10^6 pulses we were able to determine the presence and propert

Boris T. Gänsicke, Paula Szkody, Domitilla de Martino, Klaus Beuermann

Brief HST/STIS spectroscopic snapshot exposures of the cataclysmic variables 1RXSJ232953.9+062814, CE315, BZ UMa and EY Cyg reveal very large NV/CIV line flux ratios, similar to those observed in AE Aqr. Such anomalous line flux ratios have so far been observed in 10 systems, and presumably reflect a different composition of the accreted material compared to

Richard de Grijs, Gerry F. Gilmore, Rachel A. Johnson

We present the detailed analysis of Hubble Space Telescope observations of the spatial distributions of different stellar species in two young compact star clusters in the Large Magellanic Cloud (LMC), NGC 1805 and NGC 1818. Based on a comparison of the characteristic relaxation times in their cores and at their half-mass radii with the observed degree of ma

Douglas C. Leonard, Shashi M. Kanbur, Choong C. Ngeow, Nial R. Tanvir

Type II-plateau supernovae (SNe II-P) are the classic variety of core-collapse events that result from isolated, massive stars with thick hydrogen envelopes intact at the time of explosion. Their distances are now routinely estimated through two techniques: the expanding photosphere method (EPM), a primary distance-determining method, and the recently develo

Marco Feroci

In this paper I will briefly review what are, in my view, the main contributions of BeppoSAX to the understanding of the class of sources known as Soft Gamma Repeaters. These enigmatic sources were firmly identified as steady pulsars just during the operating lifetime of BeppoSAX. All the instruments onboard BeppoSAX have at some level contributed in this fi

Karl D. Gordon, Geoffrey C. Clayton, K. A. Misselt, Arlo U. Landolt

We present an exhaustive, quantitative comparison of all of the known extinction curves in the Small and Large Magellanic Clouds (SMC and LMC) with our understanding of the general behavior of Milky Way extinction curves. The R_V dependent CCM relationship and the sample of extinction curves used to derive this relationship is used to describe the general be

S. Heinz, R. Sunyaev

We derive the non-linear relation between the core flux F_{nu} of accretion powered jets at a given frequency and the mass M of the central compact object. For scale invariant jet models, the mathematical structure of the equations describing the synchrotron emission from jets enables us to cancel out the model dependent complications of jet dynamics, retain

Jorge Ananias Neto

We embed second class constrained systems by a formalism that combines concepts of the BFFT method and the unfixing gauge formalism. As a result, we obtain a gauge-invariant system where the introduction of the Wess-Zumino (WZ) field is essential. The initial phase-space variables are gauging with the introduction of the WZ field, a procedure that resembles

Vladimir Pascalutsa, Daniel R. Phillips

Model-independent effects of $Δ$(1232) excitation on nucleon polarizabilities are computed in a Lorentz-invariant fashion. We find a large effect of relative order $(M_Δ- M)/M$ in some of the spin polarizabilities, with the backward spin polarizability receiving the largest contribution. Similar subleading effects are found to be important in the fourth-orde

Craig Calcaterra, Axel Boldt

A generalization of the Flow-box Theorem is given. The assumption of continuous differentiability of the vector field is relaxed to a local Lipschitz condition. The theorem holds in any Banach space.

D. V. Ahluwalia-Khalilova, Irina Dymnikova

Electroweak gauge bosons have masses of the order of 10^2 GeV, while masses of additional bosons involved in gravito-electroweak unification are expected to be still higher. These are at least eleven orders of magnitude higher than sub-eV range indications for neutrino masses. Under these circumstances we suspect that the sub-eV particles are created in a sp

Bjorn Andreas, Daniel Hernandez Ruiperez

We analyze three aspects of N=1 heterotic string compactifications on elliptically fibered Calabi-Yau threefolds: stability of vector bundles, five-brane instanton transitions and chiral matter. First we show that relative Fourier-Mukai transformation preserves absolute stability. This is relevant for vector bundles whose spectral cover is reducible. Then we

Joao Magueijo, Lee Smolin

Non-linear special relativity (or doubly special relativity) is a simple framework for encoding properties of flat quantum space-time. In this paper we show how this formalism may be generalized to incorporate curvature (leading to what might be called ``doubly general relativity&#39;&#39;). We first propose a dual to non-linear realizations of relativity in

Michele Fabrizio, Andrew F. Ho, Lorenzo De Leo, Giuseppe E. Santoro

We study the phase diagram of a twofold orbitally degenerate Anderson impurity model which presents a non-trivial fixed point similar to the two-impurity Kondo model one. Remarkably, this fixed point is more robust than the latter one, since it can only be destabilized by orbital or gauge symmetry breaking. The impurity model is interesting per se, but here

J. N. Das, S. Paul, K. Chakrabarti

We present here triple differential cross sections for ionization of hydrogen atoms by electron impact at 1eV, 0.5eV and 0.3eV energy above threshold, calculated in the hyperspherical partial wave theory. The results are in very good agreement with the available semiclassical results of Deb and Crothers \cite{DC02} for these energies. With this, we are able

Chiangbing Li, E. Oset, M. J. Vicente Vacas

We study the four-body decays $J/ψ\to N {\bar N}$ {\it meson meson} using a chiral unitary approach to account for the meson meson final state interaction (FSI). The calculation of the $J/ψ\to N \bar N π^+ π^-$ process properly reproduces the experimental data after taking the FSI of mesons and the contribution of intermediate $ρ$ meson into account. The iso

M. Toller

We treat the events determined by a quantum physical state in a noncommutative space-time, generalizing the analogous treatment in the usual Minkowski space-time based on positive-operator-valued measures (POVMs). We consider in detail the model proposed by Snyder in 1947 and calculate the POVMs defined on the real line that describe the measurement of a sin

Y. Lemperiere, E. P. S. Shellard

We present the first concrete evidence for the classical stability of vortons, circular cosmic string loops stabilized by the angular momentum of the charge and current trapped on the string. We begin by summarizing what is known about vorton solutions and, in particular, their analytic stability with respect to a range of radial and nonradial perturbations.

Y. C. Chung, M. Heiblum, V. Umansky

The charge of fractionally charged quasiparticles, proposed by Laughlin to explain the fractional quantum Hall effect (FQHE), was recently verified by measurements. Charge q=e/3 and e/5 (e is the electron charge), at filling factors nu=1/3 and 2/5, respectively, were measured. Here we report the unexpected bunching of fractional charges, induced by an extrem

J. -M. Frere, Ernest Ma

It has recently been proposed that all fundamental fermion masses (whether Dirac or Majorana) come from effective dimension-five operators in the context of a truly minimal left-right model. We show how a particularly economical scheme emerges in a supersymmetric framework, where chiral symmetry breaking originates in the gaugino sector.

Markus H. Thoma, Joachim Truemper, Vadim Burwitz

It has been predicted that quark and hybrid stars, containing strange quark matter in their core, have a significantly smaller radius than ordinary neutron stars. Preliminary X-ray observations of isolated neutron stars indicated a surprisingly small radius consistent with quark matter in the interior of the star. However, a new analysis of the data led to a

Matt Mackie, Olavi Dannenberg, Jyrki Piilo, Kalle-Antti Suominen

We theoretically investigate Raman photoassociation of a degenerate Bose-Fermi mixture of atoms and the subsequent prospect for anomalous (Cooper) pairing between atoms and molecules. Stable fermionic molecules are created via free-bound-bound stimulated Raman adiabatic passage which, in contrast to purely bosonic systems, can occur in spite of collisions. W

Debashish Chowdhury, Dietrich Stauffer

We incorporate the generic hierarchical architecture of foodwebs into a &#34;{\it unified}&#34; model that describes both &#34;micro&#34; and &#34;macro&#34; evolutions within a single theoretical framework. This model describes the &#34;micro&#34; -evolution in detail by accounting for the birth, ageing and natural death of individual organisms as well as p

C. Hess, B. Büchner, U. Ammerahl, A. Revcolevschi

Results of in-plane and out-of-plane thermal conductivity measurements on $\rm La_{1.8-x}Eu_{0.2}Sr_xCuO_4$ ($0\leq x\leq0.2$) single crystals are presented. The most characteristic features of the temperature dependence are a pronounced phonon peak at low temperatures and a steplike anomaly at $T_{LT}$, i.e., at the transition to the low temperature tetrago

D. Bolle, Th. M. Nieuwenhuizen, I. Perez Castillo, T. Verbeiren

We introduce a spherical Hopfield-type neural network involving neurons and patterns that are continuous variables. We study both the thermodynamics and dynamics of this model. In order to have a retrieval phase a quartic term is added to the Hamiltonian. The thermodynamics of the model is exactly solvable and the results are replica symmetric. A Langevin dy

Peter Schneider

We consider the parity transformation and the consequences of parity invariance on the $n$-point correlation function of the cosmic shear, or any other polar (or `spin-2&#39;) field. The decomposition of the shear field into E- and B-modes then yields the result that any correlation function which contains an odd number of B-mode shear components vanishes fo

R. Tantalo, C. Chiosi

In this study we present detailed calculations of absorption line indices on the Lick System based on the stellar models by Salasnich et al. (2000) calculated with enhanced mix of alpha-elements. Using the so-called Response Functions (RFs) of Tripicco & Bell (1995, TB95), we calculate the indices for SSPs of different age, metallicity and enhancement. We ma

David A. Huse, Werner Krauth, R. Moessner, S. L. Sondhi

We study classical hard-core dimer models on three-dimensional lattices using analytical approaches and Monte Carlo simulations. On the bipartite cubic lattice, a local gauge field generalization of the height representation used on the square lattice predicts that the dimers are in a critical Coulomb phase with algebraic, dipolar, correlations, in excellent

Roberto Vio, Paola Andreani, Willelm Wamsteker

In this draft we comment on the results concerning the performances of matched filters, scale adaptive filters and Mexican hat wavelet that recently appeared in literature in the context of point source detection in Cosmic Microwave Background maps. In particular, we show that, contrary to what has been claimed, the use of the matched filters still appear to

V. Kataev, J. Baier, A. Moeller, L. Jongen

We present electron spin resonance data of Ti$^{3+}$ (3$d^1$) ions in single crystals of the novel layered quantum spin magnet TiOCl. The analysis of the g tensor yields direct evidence that the d_{xy} orbital from the t_{2g} set is predominantly occupied and owing to the occurrence of orbital order a linear spin chain forms along the crystallographic b axis

S. Bondarenko, M. Kozlov, E. Levin

In this paper the semi-classical approach to the solution of non-linear evolution equation is developed. We found the solution in the entire kinematic region to the non-linear evolution equation that governs the dynamics in the high parton density QCD. The large impact parameter ($b_t$) behavior of the solution is discussed as well as the way how to include

Miguel Vazquez-Prada, Alvaro Gonzalez, Javier B. Gomez, Amalio F. Pacheco

Using error diagrams, we quantify the forecasting of characteristic-earthquake occurrence in a recently introduced minimalist model. Initially we connect the earthquake alarm at a fixed time after the ocurrence of a characteristic event. The evaluation of this strategy leads to a one-dimensional numerical exploration of the loss function. This first strategy

Ting Yu, J. H. Eberly

We consider whether quantum coherence in the form of mutual entanglement between a pair of qubits is susceptible to decay that may be more rapid than the decay of the coherence of either qubit individually. An instance of potential importance for solid state quantum computing arises if embedded qubits (spins, quantum dots, Cooper pair boxes, etc.) are expose

Tota Nakamura, Shin-ichi Endoh, Takeo Yamamoto

We find a possibility of a weak universality of spin-glass phase transitions in three-dimensional $\pm J$ models. The Ising, the XY and the Heisenberg models seem to undergo finite-temperature phase transitions with a ratio of the critical exponents $γ/ν\sim 2.4$. Evaluated critical exponents may explain corresponding experimental results. The analyses are b

D. Ebert, K. G. Klimenko

The influence of a constant homogeneous external magnetic field $H$ on the formation and stability of quark droplets is investigated within a simple Nambu -- Jona-Lasinio model by using a thermodynamic approach. For a vanishing magnetic field stable quark droplets, which are schematically the bags of massless quarks, are allowed to exist only at $G>G_{bag}$,

Shi-Jie Yang, Yue Yu

We study the temperature dependence of the conductivity of the 2D electronic solid. In realistic samples, a domain structure forms in the solid and each domain randomly orients in the absence of the in-plane field. At higher temperature, the electron transport is governed by thermal activation form of $σ_{xx}(T)\propto e^{-Δ_0/k_BT}$. The impurities will loc

ZEUS Collaboration

The cross section for deeply virtual Compton scattering in the reaction ep -> e gamma p has been measured with the ZEUS detector at HERA using integrated luminosities of 95.0 pb-1 of e+p and 16.7 pb-1 of e-p collisions. Differential cross sections are presented as a function of the exchanged-photon virtuality, Q2, and the centre-of-mass energy, W, of the gam

P. Sanchez-Blazquez, J. Gorgas, N. Cardiel, A. J. Cenarro

Central line-strength indices were measured in the blue spectral region for a sample of 98 early-type galaxies in different environments. For most indices (Mgb and <Fe> in particular) ellipticals in rich clusters and in low-density regions follow the same index-sigma relations. However, striking spectral differences between field ellipticals and their counte

A. A. Nersesyan, A. M. Tsvelik

A model of carbon nanotube at half filling is studied. The Coulomb interaction is assumed to be unscreened. It is shown that this allows to develop the adiabatic approximation which leads to considerable simplifications in calculations of the excitation spectrum. We give a detailed analysis of the spectrum and the phase diagram at half filling and discuss ef

Yuri Prokhorov

We study Mori fiber spaces over a two-dimensional base which satisfy the semistability assumption. As an application of our technique we give a new proof of the existence of semistable 3-fold flips.

R. P. Malik

We discuss the (dual-)gauge transformations for the gauge-fixed Lagrangian density and establish their intimate connection with the translation subgroup T(2) of the Wigner&#39;s little group for the free one-form Abelian gauge theory in four $(3 + 1)$-dimensions (4D) of spacetime. Though the relationship between the usual gauge transformation for the Abelian

Fang Wu, Bernardo A. Huberman, Lada A. Adamic, Joshua Tyler

We present a study of information flow that takes into account the observation that an item relevant to one person is more likely to be of interest to individuals in the same social circle than those outside of it. This is due to the fact that the similarity of node attributes in social networks decreases as a function of the graph distance. An epidemic mode

Shao-Ming Fei, Xiu-Hong Gao, Xiao-Hong Wang, Zhi-Xi Wang

We consider the separability of rank two quantum states on multiple quantum spaces with different dimensions. The sufficient and necessary conditions for separability of these multiparty quantum states are explicitly presented. A nonseparability inequality is also given, for the case where one of the eigenvectors corresponding to nonzero eigenvalues of the d

Krzysztof Sacha, Bruno Eckhardt

The outgoing electrons in non-sequential multiple ionization in intense laser fields are strongly correlated. The correlations can be explained within a classical model for interacting electrons in the presence of the external field. Here we extend the previous analysis for two and three electrons to cases with up to eight electrons and identify the saddle c

Hyo Seok Yi, Ba An Nguyen, Jaewan Kim

We improve a previously proposed scheme (Phys. Rev. A 66 (2002) 065401) for generating vibrational trio coherent states of a trapped ion. The improved version is shown to gain a double advantage: (i) it uses only five, instead of eight, lasers and (ii) the generation process can be made remarkably faster.

D. Richard Kuhn

Recently proposed quantum key distribution protocols are shown to be vulnerable to a classic man-in-the-middle attack using entangled pairs created by Eve. It appears that the attack could be applied to any protocol that relies on manipulation and return of entangled qubits to create a shared key. The protocols that are cryptanalyzed in this paper were prove

B. Navarro, I. L. Egusquiza, J. G. Muga, G. C. Hegerfeldt

Atomic detection by fluorescence may fail because of reflection from the laser or transmission without excitation. The detection probability for a given velocity range may be improved by controlling the detuning and the spatial dependence of the laser intensity. A simple optimization method is discussed and exemplified.

Zbyszek P. Karkuszewski

It is impossible to obtain accurate frequencies from time signals of a very short duration. This is a common believe among contemporary physicists. Here I present a practical way of extracting energies to a high precision from very short time signals produced by a quantum system. The product of time span of the signal and the precision of found energies is w

N. L. Chuprikov

A complete one-dimensional scattering of a spinless particle on a time-independent potential barrier is considered. To describe separately transmitted and reflected particles in the corresponding subsets of identical experiments, we introduce the notions of scattering channels for transmission and reflection. We find for both channels the (unitary) scatterin

Jiangfeng Du, Hui Li, Xiaodong Xu, Xianyi Zhou

The discontinuous dependence of the properties of a quantum game on its entanglement has been shown up to be very much like phase transitions viewed in the entanglement-payoff diagram [J. Du et al., Phys. Rev. Lett, 88, 137902 (2002)]. In this paper we investigate such phase-transition-like behavior of quantum games, by suggesting a method which would help t