May 2003 arXiv papers — page 21

Lie-Wen Chen, V. Greco, C. M. Ko, Bao-An Li

Using an isospin-dependent transport model, we study isospin effects on two-nucleon correlation functions in heavy-ion collisions induced by neutron-rich nuclei at intermediate energies. We find that these correlation functions are sensitive to the density dependence of nuclear symmetry energy, but not to the incompressibility of symmetric nuclear matter and

Jeremiah P. Ostriker, Kentaro Nagamine, Renyue Cen, Masataka Fukugita

While second and higher order correlations of the light distribution have received extensive study, the lowest order probability distribution function (PDF) -- the probability that a unit volume of space will emit a given amount of light -- has received very little attention. We estimate this function with the aid of hydrodynamic simulations of the Lambda CD

X. Dupac, C. del Burgo, J. -P. Bernard, M. Giard

Submillimetre maps of NGC 891 have been obtained with the PRONAOS balloon-borne telescope and with the ISOPHOT instrument on board the ISO satellite. In this article, we also gather data from IRAS and SCUBA to present the complete submillimetre spectrum of this nearby edge-on spiral galaxy. We derive submillimetre emission profiles along the major axis. The

S. Matarrese, M. Pietroni, C. Schimd

Non-linear gravitational clustering in a universe dominated by dark energy, modelled by a `quintessence' scalar field, and cold dark matter with space-time varying mass is studied. Models of this type, where the variable mass is induced by dependence on the scalar field, as suggested by string theory or extra-dimensions, have been proposed as a viable so

Elisabetta Di Grezia, Giampiero Esposito, Agostino Funel, Gianpiero Mangano

This paper investigates the possible cosmological implications of the presence of an antisymmetric tensor field related to a lack of commutatitivity of spacetime coordinates at the Planck era. For this purpose, such a field is promoted to a dynamical variable, inspired by tensor formalism. By working to quadratic order in the antisymmetric tensor, we study t

Pietro Parruccini

The critical behavior of frustrated spin systems with nonplanar orderings is analyzed by a six-loop study in fixed dimension of an effective O$(N) \times $O$(M)$ Landau-Ginzburg-Wilson Hamiltonian. For this purpose the large-order behavior of the field theoretical expansion is determined. No stable fixed point is found in the physically interesting case of $

E. Rol, R. A. M. J. Wijers, J. P. U. Fynbo, J. Hjorth

We present polarimetric observations of the afterglow of gamma-ray burst (GRB) 021004, obtained with the Nordic Optical Telescope (NOT) and the Very Large Telescope (VLT) between 8 and 17 hours after the burst. Comparison among the observations shows a 45 degree change in the position angle from 9 hours after the burst to 16 hours after the burst, and compar

R. Menezes, J. R. S. Nascimento, R. F. Ribeiro, C. Wotzasek

We study the duality symmetry in p-form models containing a generalized $B_q\wedge F_{p+1}$ term in spacetime manifolds of arbitrary dimensions. The equivalence between the $B_q\wedge F_{p+1}$ self-dual ($SD_{B\wedge F}$) and the $B_q\wedge F_{p+1}$ topologically massive ($TM_{B\wedge F}$) models is established using a gauge embedding procedure, including th

Krisztian Peters, Gian Paolo Vacca

We investigate the role of a certain class of QCD corrections to electroweak vector boson scattering at small scattering angles and large energies. These are present since, from the perturbative analysis, the vector bosons may dissociate into quark-antiquark pairs giving rise to colour dipoles interacting through gluon exchanges. After the computation of the

C. Koenigsdoerffer, G. Faye, G. Schaefer

We specialize the radiation-reaction part of the Arnowitt-Deser-Misner (ADM) Hamiltonian for many non-spinning point-like bodies, calculated by Jaranowski and Schaefer [1], to third-and-a-half post-Newtonian approximation to general relativity, to binary systems. This Hamiltonian is used for the computation of the instantaneous gravitational energy loss of a

Parampreet Singh, M. Sami, Naresh Dadhich

We study the general features of the dynamics of the phantom field in the cosmological context. In the case of inverse coshyperbolic potential, we demonstrate that the phantom field can successfully drive the observed current accelerated expansion of the universe with the equation of state parameter $w_ϕ < -1$. The de-Sitter universe turns out to be the late

E. Z. Kuchinskii, M. V. Sadovskii, N. A. Strigina

We analyze properties of superconducting state (for both s-wave and d-wave pairing), appearing on the &#34;background&#34; of the pseudogap state, induced by fluctuations of &#34;dielectric&#34; (AFM(SDW) or CDW) short -- range order in the model of the Fermi surface with &#34;hot spots&#34;. We present microscopic derivation of Ginzburg - Landau expansion,

K. Hagino, Nguyen Van Giai

We investigate the properties of single-particle resonances in a non-spherical potential by solving the coupled-channels equations for the radial wave functions. We first generalize the box discretization method for positive energy states to a deformed system. As in the spherical case, we find that the discretized energy is stabilized against the box size wh

S. Kasuya, M. Kawasaki, Fuminobu Takahashi

We study the curvaton scenario using the MSSM flat directions in the gauge-mediated SUSY breaking model. We find that the fluctuations in the both radial and phase directions can be responsible for the density perturbations in the universe through the curvaton mechanism. Although it has been considered difficult to have a successful curvaton scenario with th

Patricia Conde

The b-bbar production cross section in 920 GeV proton - nucleus collisions was obtained with the HERA-B detector, using a sample of 1.35 million of di-lepton triggered events taken during the 2000 physics run. The b-bbar events are identified via the inclusive decay b->J/psi, where the J/Psi mesons decay to mu+mu- or e+e-. The b events are separated from dir

Brett McInnes

Recently it has been argued that, because tachyonic matter satisfies the Strong Energy Condition [SEC], there is little hope of avoiding the singularities which plague S-Brane spacetimes. Meanwhile, however, Townsend and Wohlfarth have suggested an ingenious way of circumventing the SEC in such situations, and other suggestions for actually violating it in t

Akiko Miyake

We find that the IIA Matrix models defined on the non-compact $C^3/Z_6$, $C^2/Z_2$ and $C^2/Z_4$ orbifolds preserve supersymmetry where the fermions are on-mass-shell Majorana-Weyl fermions. In these examples supersymmetry is preserved both in the orbifolded space and in the non-orbifolded space at the same time. The Matrix model on $C^3/Z_6$ orbifold has th

Namit Mahajan

The PCT theorem is shown to be valid in quantum field theory formulated on noncommutative spacetime by exploiting the properties of the Wightman functions defined in such a set up.

H. W. Huang, T. Morii

We calculate the one-loop QCD virtual corrections to all helicity amplitudes for parton level virtual Compton scattering processes. We include the amplitudes both on quark target process $γ^* q\toγq$ and on gluon target process $γ^*g\toγg$. The infrared pole structure of the amplitudes is in agreement with the prediction of Catani&#39;s general formalism for

Debajyoti Choudhury, Debashis Ghoshal, Dileep P. Jatkar, Sudhakar Panda

We study a string theory inspired model for hybrid inflation in the context of a brane-antibrane system partially compactified on a compact submanifold of (a caricature of) a Calabi-Yau manifold. The interbrane distance acts as the inflaton, whereas the end of the inflationary epoch is brought about by the rapid rolling of the tachyon. The number of e-foldin

Teruaki Inagaki, Yoshio Kikukawa, Hiroshi Suzuki

The axial anomaly arising from the fermion sector of $\U(N)$ or $\SU(N)$ reduced model is studied under a certain restriction of gauge field configurations (the ``$\U(1)$ embedding&#39;&#39; with $N=L^d$). We use the overlap-Dirac operator and consider how the anomaly changes as a function of a gauge-group representation of the fermion. A simple argument sho

Xiaoguang Wang, Barry C. Sanders

We study relations between bosonic quadrature squeezing and atomic spin squeezing, and find that the latter reduces to the former in the limit of a large number of atoms for even and odd states. We demonstrate this reduction by treating even and odd spin coherent states, for which analytical solutions are readily obtained, and prove that even spin coherent s

Eric E. Mamajek

I discuss results from the recent spectroscopic survey for solar-type pre-MS stars in the Lower Centaurus-Crux (LCC) and Upper Centaurus-Lupus (UCL) OB subgroups by Mamajek, Meyer, & Liebert (2002, AJ, 124, 1670). LCC and UCL are subgroups of the Sco-Cen OB association, and the two nearest OB subgroups to the Sun. In the entire survey of 110 pre-main sequenc

Paulo F. Bedaque, Gautam Rupak, Martin J. Savage

At the high densities present in the interior of neutron stars, the neutrons are condensed into the 3P2 superfluid phase. While this condensation has little impact on the equation of state, it can have an important role in determining the low-temperature energy-momentum transport properties. The spontaneous breaking of baryon number by the condensate gives r

J. L. Noronha, D. Rocha, M. S. Guimarães, C. Wotzasek

We study the soldering formalism in the context of abelian p-form theories. We develop further the fusion process of massless antisymmetric tensors of different ranks into a massive p-form and establish its duality properties. To illustrate the formalism we consider two situations. First the soldering mass generation mechanism is compared with the Higgs and

Kaige Wang, Shiyao Zhu

We study a general theory on the interference of two-photon wavepacket in a beam splitter. We find that the symmetry of two-photon spectrum plays an important role in the manners of interference. We distinguish the coalescence and anti-coalescence interferences, and prove that the anti-coalescence interference is the signature of photon entanglement.

H. Gopalkrishna Gadiyar, K. M. Sangeeta Maini, R. Padma, H. S. Sharatchandra

In this note we point out the fact that the proper conceptual setting of quantum computation is the theory of Linear Time Invariant systems. To convince readers of the utility of the approach, we introduce a new model of computation based on the orthogonal group. This makes the link to traditional electronics engineering clear. We conjecture that the speed u

Mitja Perus, Horst Bischof

The Hopfield neural networks and the holographic neural networks are models which were successfully simulated on conventional computers. Starting with these models, an analogous fundamental quantum information processing system is developed in this article. Neuro-quantum interaction can regulate the &#34;collapse&#34;-readout of quantum computation results.

Louis Sica

Correlations for the Bell gedankenexperiment are constructed using probabilities given by quantum mechanics, and nonlocal information. They satisfy Bell&#39;s inequality and exhibit spatial non stationarity in angle. Correlations for three successive local spin measurements on one particle are computed as well. These correlations also exhibit non stationarit

C. Schroll, W. Belzig, C. Bruder

We derive a model to describe decoherence of atomic clouds in atom-chip traps taking the excited states of the trapping potential into account. We use this model to investigate decoherence for a single trapping well and for a pair of trapping wells that form the two arms of an atom interferometer. Including the discrete spectrum of the trapping potential giv

K. Kowalski, J. Rembielinski

In the preceding Comment (quant-ph/0209032) Trifonov disputes our recently proposed uncertainty relations for a quantum particle on a circle. He states that (i) the quantity $Δ^2(\hatϕ)$ introduced by us representing the uncertainty of the angle is not a proper measure of the position uncertainty and therefore the proposed inequalities can hardly be qualifie

Benjamin Lev

Many proposals for quantum information processing require precise control over the motion of neutral atoms, as in the manipulation of coherent matter waves or the confinement and localization of individual atoms. Patterns of micron-sized wires, fabricated lithographically on a flat substrate, can conveniently produce large magnetic-field gradients and curvat

Subhash Kak

The question of the measurements on the Bell states by making use of mode change (from mixed to pure) of one qubit is considered. Such a mode change cannot be taken advantage of for superluminal communication in teleportation, and it may define constraints on the size of the gates.

Patrick C. Chaumet, Adel Rahmani, Garnett W. Bryant

We present a generalization of the coupled dipole method to the scattering of light by arbitrary periodic structures. This new formulation of the coupled dipole method relies on the same direct-space discretization scheme that is widely used to study the scattering of light by finite objects. Therefore, all the knowledge acquired previously for finite system

S. Gordienko, D. V. Fisher, J. Meyer-ter-Vehn

A closed expression for the momentum evolution of a test particle in weakly-coupled plasma is derived, starting from quantum many particle theory. The particle scatters from charge fluctuations in the plasma rather than in a sequence of independent binary collisions. Contrary to general belief, Bohr&#39;s (rather than Bethe&#39;s) Coulomb logarithm is the re

Thor Gjesdal, Carl Erik Wasberg, Oyvind Andreassen

This paper is divided in two parts. In the first part, a brief review of a spectral element method for the numerical solution of the incompressible Navier-Stokes equations is given. The method is then extended to compute buoyant flows described by the Boussinesq approximation. Free convection in closed two-dimensional cavities are computed and the results ar

George Kahrimanis

Motivation. This version is based solely on the calculus of probability, excluding any statistical principle. &#34;Location measurement&#34; means the pdf of the error is known. When the datum is obtained, intuition suggests something like a pdf for the parameter; here we attempt a critical examination of its meaning. Summary. In default of prior probability

A. Frank, J. Barea, R. Bijker

Extensions of nuclear supersymmetry are discussed, together with a proposal for new, more stringent and precise tests that probe the susy classification and specific two-particle correlations among supersymmetric partners. The combination of these theoretical and experimental studies may play a unifying role in nuclear phenomena.

S. K. Bogner, T. T. S. Kuo, A. Schwenk

We present detailed results for the model-independent low momentum nucleon-nucleon interaction V_{low k}. By introducing a cutoff in momentum space, we separate the Hilbert space into a low momentum and a high momentum part. The renormalization group is used to construct the effective interaction V_{low k} in the low momentum space, starting from various hig

Raj K. Gupta, Rajesh Kumar, Narinder K. Dhiman, M. Balasubramaniam

The decay of $^{56}Ni^*$, formed in $^{32}S+^{24}Mg$ reaction at the incident energies $E_{cm}$=51.6 and 60.5 MeV, is calculated as a cluster decay process within the Preformed Cluster-decay Model (PCM) of Gupta et al. re-formulated for hot compound systems. The observed deformed shapes of the exit channel fragments are simulated by introducing the neck-leng

V. A. Khitrov, A. M. Sukhovoj, Pham Dinh Khang, Vo Thi Anh

The most important systematical errors in determination of level density and radiative strength functions for deformed nuclei have been estimated from the gamma-ray spectra in nuclear reactions like the stripping or pickup reactions.

A. Arnold, R. Bosi, S. Jeschke, E. Zorn

This paper is concerned with the well-posedness analysis of the Hartree-Fock system modeling the time evolution of a quantum system comprised of fermions. We consider quantum states with finite mass and finite kinetic energy, and the self-consistent potential is the unbounded Coulomb interaction. This model is first formulated as a semi-linear evolution prob

Senya Shlosman, Valentin Zagrebnov

We present a non mean-field model which undergoes a magnetostriction phase transition in the temperature. That is, the crystal becomes sharply contracted and magnetized once the temperature passes below the critical value

Deepak Parashar

We investigate the algebro-geometric structure of a novel two-parameter quantum deformation which exhibits the nature of a semidirect or cross-product algebra built upon GL(2) x GL(1), and is related to several other known examples of quantum groups. Following the R-matrix framework, we construct the L+/- functionals and address the problem of duality for th

Daniel Dugger

The paper summarizes the construction of pairings on some standard spectral sequences in algebraic topology.

Vincent Colin, Emmanuel Giroux, Ko Honda

We present a sketch of the proof of the following theorems: (1) Every 3-manifold has only finitely many homotopy classes of 2-plane fields which carry tight contact structures. (2) Every closed atoroidal 3-manifold carries finitely many isotopy classes of tight contact structures.

Ronaldo Garcia, Jorge Sotomayor

In the space $\mathbb U^4$ of cubic forms of surfaces, regarded as a $G$-space and endowed with a natural invariant metric, the ratio of the volumes of those representing umbilic points with negative to those with positive indexes is evaluated in terms of the asymmetry of the metric, defined here. A connection of this ratio with that reported by Berry and Ha

D. Kotschick, S. Morita

For any closed oriented surface F of genus at least three, we prove the existence of foliated F-bundles over surfaces such that the signatures of the total spaces are non-zero. We can arrange that the total holonomy of the horizontal foliations preserve a prescribed symplectic form on the fiber. We relate the cohomology class represented by the transverse sy

Xiaoping Xu

Given a weight of sl(n), we derive a system of variable-coefficient second-order linear partial differential equations that determines the singular vectors in the corresponding Verma module. Moreover, we completely solve the system in a certain space of power series. The polynomial solutions correspond to the singular vectors in the Verma module. The well-kn

Yoshikazu Katayama, Masamichi Takesaki

We associate a cohomological invariant to each outer action of a group on a factor, and classify them by the invariant in the case that the group is a countable discrete amenable group and the factor is appoximately finite dimensional. The invariant defined for the group Out(M)=Aut(M)/Int(M) is called the intrinsic modular obstruction. The invariant for an o

Joanna Domienik, Piotr Kosinski

We construct the set of theories which share the property that the tree-level amplitudes nullify even if both initial and final states contain the same type of particles. The origin of this phenomenon lies in the fact that the reduced classical dynamics describes isochronic systems.

K. Sfetsos

We construct plane wave backgrounds with time-dependent profiles corresponding to Penrose limits of NS5-branes with transverse space symmetry group broken from SO(4) to SO(2)\times Z_N. We identify the corresponding exact theory as the five-dimensional Logarithmic Conformal Field Theory (CFT) arising from the contraction of the SU(2)_{N&#39;}/U(1)\times SL(2

Suresh Govindarajan, Jaydeep Majumder

We identify type IIA orientifolds that are dual to M-theory compactifications on manifolds with G_2-holonomy. We then discuss the construction of crosscap states in Gepner models. (Based on a talk presented by S.G. at PASCOS 2003 held at the Tata Institute of Fundamental Research, Mumbai during Jan. 3-8, 2003.)

Ignacio Cortese, J. Antonio Garcia

We analyze the relation between the concept of auxiliary variables and the Inverse problem of the calculus of variations to construct a Lagrangian from a given set of equations of motion. The problem of the construction of a consistent second order dynamics from a given first order dynamics is investigated. At the level of equations of motion we find that th

V. A. Smirnov

The dimensionally regularized massless on-shell planar triple box Feynman diagram with powers of propagators equal to one is analytically evaluated for general values of the Mandelstam variables s and t in a Laurent expansion in the parameter \ep=(4-d)/2 of dimensional regularization up to a finite part. An explicit result is expressed in terms of harmonic p

P. Colangelo, F. De Fazio

We analyze the hadronic and radiative decay modes of the recently observed $D_{sJ}(2317)$ meson, in the hypothesis that it can be identifield with the scalar $s_\ell^P={1\over 2}^+$ state of $c \bar s$ spectrum ($D_{s0}$). The method is based on heavy quark symmetries and Vector Meson Dominance ansatz. We find that the hadronic isospin violating mode $D_{s0}

C. Giunti

I review the current status of solar, KamLAND, atmospheric and K2K neutrino experiments, implications for three-neutrino mixing and upper bounds for the neutrino masses.

Carlos E. Yaguna

We show that the predictions for lepton flavor violating decays, in the case of quasi-degenerate neutrinos, change drastically when we include in the computation the high-energy phases present in the matrix of neutrino Yukawa couplings.

V. V. Vechernin, R. S. Kolevatov

The long-range $p_t$ and multiplicity($n$) correlations in high-energy nuclear collisions are studied in the framework of a simple cellular analog of the string fusion model. Two cases with local and global string fusion is considered. The $p_t$--$n$ and $n$--$n$ correlation functions and correlation coefficients are calculated analytically in some asymptoti

Andreas Nyffeler

We review the present status of the theoretical evaluation of the anomalous magnetic moment of the the muon within the Standard Model. We mainly focus on the hadronic contributions in the muon g-2 due to vacuum polarization effects, light-by-light scattering and higher order electroweak corrections. We discuss some recent calculations together with their unc

V. N. Baier, V. M. Katkov

The cross section of bremsstrahlung from high-energy electron suppressed due to the multiple scattering of an emitting electron in a dense media (the LPM effect) is discussed. Development of the LPM effect theory is outlined. For the target of finite thickness one has to include boundary photon radiation as well as the interference effects. The importance of

A. Broncano

The effective Lagrangian for the seesaw model is derived. Besides the usual dimension-5 operator responsible for light neutrino masses, a dimension-6 operator is included which, for three or less heavy neutrino generations, provides a generic link between low-energy observables and all physical parameters of the high-energy seesaw Lagrangian. Leptogenesis ca

Ines Wetzorke

Recent progress of lattice investigations in thermal physics is summarized in this contribution. Hadronic spectral functions can be reconstructed from correlation functions in Euclidean time based on the Maximum Entropy Method without a priori assumptions on the spectral shape. The thermal modifications of hadron properties are investigated in the scalar, ps

Simona Rolli

We report on the first results from the CDF experiment on search for physics beyond the Standard Model using data from the upgraded TeVatron collider running $p\bar p$ collisions at $\sqrt{s}$ = 1960 GeV. These first results, although obtained with a total integrated luminosity lower than the total integrated luminosity collected during Run I, are already co

S. K. Swain

Results on the decays $B^{-} \to D_{CP}K^{-}$, $\bar{B^{0}} \to D^{(*)0}\bar{K}^{(*)0}$, $B^{0} \to D^{*\mp}π^{\pm}$ and their charge conjugates using data collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric $e^{+}e^{-}$ storage ring are reported. The implications for the determination of the weak phase $ϕ_{3}$ are discussed.

Evelyne Delmeire

During the LEP2 period the e+e- collider increased its center of mass energy from 161 GeV to 209 GeV and a total integrated luminosity of approximately 700 pb-1 was recorded per experiment. Pairs of W bosons are produced and allow the study of gauge boson couplings involving W, Z and photon. The coupling of the W boson to the neutral gauge bosons have been m

R. V. Kowalewski

These lectures present the phenomenology of B meson decays and their impact on our understanding of CP violation in the quark sector, with an emphasis on measurements made at the e+e- B factories. Some of the relevant theoretical ideas such as the Operator Product Expansion and Heavy Quark Symmetry are introduced, and applications to the determination of CKM

S. Kluth

We report on recent studies of QCD performed using reanalysed e+e- annihilation data recorded at centre of mass energies 14<sqrt(s)<44 GeV by the JADE experiment operated 1979 to 1986 at the PETRA e+e- collider at DESY, Hamburg, Germany. The data for some event shape observables are compared to modern Monte Carlo event generators using parameter values obtai

DIRAC Collaboration

The DIRAC spectrometer has been commissioned at CERN with the aim of detecting $π^+ π^-$ atoms produced by a 24 GeV/$c$ high intensity proton beam in thin foil targets. A challenging apparatus is required to cope with the high interaction rates involved, the triggering of pion pairs with very low relative momentum, and the measurement of the latter with reso

Johannes Haller

The H1 and ZEUS collaborations have searched for signals of physics beyond the Standard Model in ep collisions at a center-of-mass energy of 301-319 GeV. During the HERA I phase each experiment accumulated an integrated luminosity of about 110 pb^{-1} for e^+p and about 15 pb^{-1} for e^-p collisions. The data have been analysed searching for contact interac

Abel Camacho

In this essay it will be shown that the introduction of a modification to Heisenberg algebra (here this feature means the existence of a minimal obserlvable length), as a fundamental part of the quantization process of the electrodynamical field, renders states in which the uncertainties in the two quadrature components violate the usual Heisenberg uncertain

Guillermo F. Rubilar, Yuri N. Obukhov, Friedrich W. Hehl

In conventional Maxwell--Lorentz electrodynamics, the propagation of light is influenced by the metric, not, however, by the possible presence of a torsion T. Still the light can feel torsion if the latter is coupled nonminimally to the electromagnetic field F by means of a supplementary Lagrangian of the type l^2 T^2 F^2 (l = coupling constant). Recently Pr

M. Ferraris, M. Francaviglia, M. Raiteri

We present an alternative field theoretical approach to the definition of conserved quantities, based directly on the field equations content of a Lagrangian theory (in the standard framework of the Calculus of Variations in jet bundles). The contraction of the Euler-Lagrange equations with Lie derivatives of the dynamical fields allows one to derive a varia

Guido Rizzi, Matteo Luca Ruggiero

The phase shift due to the Sagnac Effect, for relativistic matter beams counter-propagating in a rotating interferometer, is deduced on the bases of a a formal analogy with the the Aharonov-Bohm effect. A procedure outlined by Sakurai, in which non relativistic quantum mechanics and newtonian physics appear together with some intrinsically relativistic eleme

Gene Kim, MyungHo Kim

In this paper, we consider a series of events observed at spaced time intervals and present a method of representation of the series. To explain an idea, by dealing with a set of gene expression data, which could be obtained from developmental biology, the procedures are sketched with comments in some details. We mean representation by choosing a proper func

C. A. Johnson

A method is presented for computing minimal answers in disjunctive deductive databases under the disjunctive stable model semantics. Such answers are constructed by repeatedly extending partial answers. Our method is complete (in that every minimal answer can be computed) and does not admit redundancy (in the sense that every partial answer generated can be

C. E. Pryor, M. E. Flatté

A quantum dot spin LED provides a test of carrier spin injection into a qubit, as well as a means of analyzing carrier spin injection in general and local spin polarization. The polarization of the observed light is, however, significantly influenced by the dot geometry so the spin may be more polarized than the emitted light would naively suggest. We have c

Tanya Prozorov, Ruslan Prozorov, Alexey Snezhko, Kenneth S. Suslick

Ultrasonic irradiation of magnesium diboride slurries in decalin produces material with significant inter-grain fusion. Sonication in the presence of Fe(CO)5 produces magnetic Fe2O3 nanoparticles embedded in the MgB2 bulk. The resulting superconductor-ferromagnet composite exhibits considerable enhancement of the magnetic hysteresis, which implies an increas

Dung-Hai Lee, Jon Magne Leinaas

In this paper we point out that in addition to the density of states effect proposed in Ref.\cite{durst,anderson} one should consider the effect of constructive interference between the multi-MM-wave-photon processes shown in Fig.2. This process enhances the dark value of the conductivity. When the sample is very pure, i.e., when the transport life time is v

Jianming Bai

Formula for calculating the atomic scattering factor for spherical x-ray waves is derived and used to solve the near field effects problem in X-ray Fluorescence Holography theory. A rigorous formalism to calculate the X-ray fluorescence hologram for given atomic distributions is then given so that quantitative structural information can be derived from XFH m

Wei-Xue Li, Catherine Stampfl, Matthias Scheffler

Extensive density-functional theory calculations, and taking into account temperature and pressure, affords a comprehensive picture of the behavior and interaction of oxygen and Ag(111), and provides valuable insight into the function of silver as an oxidation catalyst. The obtained phase-diagram reveals the most stable species present in a given environment

M. Abolfath, A. H. MacDonald, L. Radzihovsky

Filling factor $ν=1$ bilayer electron systems in the quantum Hall regime have an excitonic-condensate superfluid ground state when the layer separation $d$ is less than a critical value $d_c$. On a quantum Hall plateau current injected and removed through one of the two layers drives a dissipationless edge current that carries parallel currents, and a dissip

Gordon Baym

We calculate the in-plane modes of the vortex lattice in a rotating Bose condensate from the Thomas-Fermi to the mean-field quantum Hall regimes. The Tkachenko mode frequency goes from linear in the wavevector, $k$, for lattice rotational velocities, $Ω$, much smaller than the lowest sound wave frequency in a finite system, to quadratic in $k$ in the opposit

R. Schumann, L. Jahn

The thermal remagnetization (TR), i.e. the reentrance of magnetization upon heating in a steady-field demagnetized sample, is a common feature to the four types of polycrystalline permanent magnets, mainly utilized for practical purposes, i.e. barium ferrites, SmCo5, Sm2Co17 and NdFeB magnets. The effect is small for pinning controlled and large for nucleati

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

The thermally activated magnetic relaxation in two-dimensional ensembles of dipolar interacting nanoparticles with large uniaxial perpendicular anisotropy is studied by a numerical method and within the mean-field approximation. The role that the correlation effects in the presence of a bias magnetic field and taking into account the lattice structure play i

J. C. Chen, A. M. Chang, M. R. Melloch

Strong electron and spin correlations in a double-quantum-dot (DQD) can give rise to different quantum states. We observe a continuous transition from a Kondo state exhibiting a single-peak Kondo resonance to another exhibiting a double peak by increasing the inter-dot-coupling (t) in a parallel-coupled DQD. The transition into the double-peak state provides

Pierpaolo Bruscolini, Fabio Cecconi

We study the thermodynamical properties of a topology-based model proposed by Galzitskaya and Finkelstein for the description of protein folding. We devise and test three different mean-field approaches for the model, that simplify the treatment without spoiling the description. The validity of the model and its mean-field approximations is checked by applyi

T. C. Choy, A. H. Harker, A. M. Stoneham

The classic theory of electron field emission from a cold metal surface due to Fowler and Nordheim (FN) is re-examined and found to violate the validity criteria for the WKB approximation, for electric fields greater than about 1V per micron. In this study we shall examine the complete solution without invoking the WKB approximation in order to assess the re

Mauro Copelli, Rita M. Zorzenon dos Santos, Daniel A. Stariolo

Recently we have used a cellular automata model which describes the dynamics of a multi-connected network to reproduce the refractory behavior and aging effects obtained in immunization experiments performed with mice when subjected to multiple perturbations. In this paper we investigate the similarities between the aging dynamics observed in this multi-conn

Alain Delgado, Augusto Gonzalez

A consistent calculation of resonant inelastic (Raman) scattering amplitudes for relatively large quantum dots, which takes account of valence-band mixing, discrete character of the spectrum in intermediate and final states, and interference effects, is presented. Raman peaks in charge and spin channels are compared with multipole strengths and with the dens

Marko Sysi-Aho, Anirban Chakraborti, Kimmo Kaski

In this paper we introduce adaptation mechanism based on genetic algorithms in minority games. If agents find their performances too low, they modify their strategies in hope to improve their performances and become more successful. One aim of this study is to find out what happens at the system as well as at the individual agent level. We observe that adapt

T. Jarlborg

Some doped semiconductors have recently been shown to display superconductivity or weak ferromagnetism. Here we investigate the electronic structure and conditions for magnetism in a supercells of cubic XW_{26}O_{81}, where X=Nb,V and Re. The undoped material is an insulator, and although the slightly doped material is a metal, it is far from the Stoner crit

B. Davoudi, R. Asgari, M. Polini, M. P. Tosi

We present an analytic theory of the spin-resolved pair distribution functions $g_{σσ&#39;}(r)$ and the ground-state energy of an electron gas with an arbitrary degree of spin polarization. We first use the Hohenberg-Kohn variational principle and the von Weizsäcker-Herring ideal kinetic energy functional to derive a zero-energy scattering Schrödinger equati

L. Angelani, G. Ruocco, M. Sampoli, F. Sciortino

Features of the energy landscape sampled by supercooled liquids are numerically analyzed for several Lennard-Jones like model systems. The properties of quasisaddles (minima of the square gradient of potential energy W=|grad V|^2), are shown to have a direct relationship with the dynamical behavior, confirming that the quasisaddle order extrapolates to zero

M. Caselle, F. Di Cunto, P. Provero

Gene regulation in Eukaryotes is mainly effected through transcription factors binding to rather short recognition motifs generally located upstream of the coding region. We present a novel computational method to identify regulatory elements in the upstream region of Eukaryotic genes. The genes are grouped in sets sharing an overrepresented short motif in t

A. Laszkiewicz, Sz. Szymczak, S. Cebrat

We have simulated demographic changes in the human population using the Penna microscopic model, based on the simple Monte Carlo method. The results of simulations have shown that during a few generations changes in the genetic pool of a population are negligible, while improving the methods of compensation of genetic defects or genetically determined pronen

Ajit Kumar Mahapatro, Subhasis Ghosh

Understanding the charge carrier transport in the disordered organic molecular semiconductors is a fascinating and still unresolved problem in modern condensed-matter physics, yet has an extremely important bearing on their application in ``plastic&#39;&#39; based field effect transistor, light emitting diodes and lasers. The most contentious issue in this s

Erik Koch, Olle Gunnarsson, Samuel Wehrli, Manfred Sigrist

The proposal of using the field-effect for doping organic crystals has raised enormous interest. To assess the feasibility of such an approach, we investigate the effect of a strong electric field on the electronic structure of C60 crystals. Calculating the polarization of the molecules and the splittings of the molecular levels as a function of the external

Jun Sugiyama, Hiroshi Itahara, Jess H. Brewer, Eduardo J. Ansaldo

The nature of the magnetic transition of the Na-rich thermoelectric Na$_{0.75}$CoO$_2$ at 22K was studied by positive muon-spin-rotation and relaxation ($μ^+$SR) spectroscopy, using a polycrystalline sample in the temperature range between 300 and 2.5 K. Zero field $μ$SR measurements indicated the existence of a static internal magnetic field at temperatures

Feng Yuan, Jihong Qin, Shiping Feng, Wei Yeu Chen

Within the t-J model, we study the charge transport in underdoped bilayer cuprates by considering the bilayer interaction. Although the bilayer interaction leads to the band splitting in the electronic structure, the qualitative behavior of the charge transport is the same as in the case of single layer cuprates. The conductivity spectrum shows a low-energy