June 2001 arXiv papers — page 8

S. H. Lubow, G. I. Ogilvie

In a planetary system, a secular particle resonance occurs at a location where the precession rate of a test particle (e.g. an asteroid) matches the frequency of one of the precessional modes of the planetary system. We investigate the secular interactions of a system of mutually inclined planets with a gaseous protostellar disk that may contain a secular no

Elisabete M. de Gouveia Dal Pino, Alex Lazarian

(Abridged) We have recently proposed that the ultra-high energy cosmic rays (UHECRs) observed above the GZK limit could be mostly protons accelerated in reconnection sites just above the magnetosphere of newborn millisecond pulsars originated by accretion induced collapse (AIC-pulsars). Although the expected rate of AIC sources in our own Galaxy is very smal

Sergei Nayakshin, Demos Kazanas

We perform a first study of time-dependent X-ray reflection in photo-ionized accretion disks. We assume a step-functional change in the X-ray flux and use a simplified prescription to describe the time evolution of the illuminated gas density profile in response to changes in the flux. We find that the dynamical time for re-adjustment of the hydrostatic bala

C. Deffayet, G. Dvali, G. Gabadadze

Recently we proposed that the acceleration of the Universe could be due to gravity leaking to extra dimensions. This scenario gives an alternative to the cosmological constant or quintessence. In [astro-ph/0106274] the authors claimed that this proposal is strongly disfavored if not ruled out by the existing data on Supernovae, Cosmic Microwave Background an

E. Behar, J. Cottam, J. R. Peterson, M. Sako

It is common to suggest the uncertainties in the atomic data for explaining difficulties that arise in interpreting astrophysical x-ray spectra. The atomic data for the Fe L-shell ions have, over the years, been considered particularly suspect. In this paper, we confront Fe-L spectra calculated using the HULLAC atomic code assuming coronal conditions with re

S. Verani, C. Barbieri, C. R. Benn, G. Cremonese

Enhancements of the Na emission and temperature from the lunar atmosphere were reported during the Leonids meteor showers of 1995, 1997 and 1998. Here we report a search for similar enhancement during the 1999 Quadrantids, which have the highest mass flux of any of the major streams. No enhancements were detected. We suggest that different chemical-physical

P. P. Sorokin, J. H. Glownia

A model is suggested to explain the frequently observed presence of intense, narrow-band, H(alpha) emission lines in the optical spectra of reddened, early-type stars (e.g. HD 44179, IRAS 18179-1346, IRAS 20298+4011). It is proposed that hydrogen atoms surrounding compact H II regions enveloping such stars become coherently phased via a nonlinear photonic me

R. Della Ceca, S. Pellegrini, L. Bassani, V. Beckmann

We discuss BeppoSAX observations and archive ASCA data of NGC 7679, a nearby, nearly face-on SB0 galaxy in which starburst and AGN activities coexist. The X-ray observations reveal a bright (L_{0.1-50 keV} \sim 2.9 \times 10^{43} erg s^{-1}) and variable source having a minimum observed doubling/halving time scale of \sim 10 - 20 ksec. A simple power law wit

D. C. Stephens, M. S. Marley, K. S. Noll, N. Chanover

We present K- and L-band photometry obtained with the Keck I telescope for a representative sample of L and T dwarfs. These observations were motivated in part by the dominant role water and methane play in shaping the flux near 2 and 3 microns and by the potential use of these bands as indicators of spectral class in the infrared. In addition, these observa

J. W. Keen, D. F. Buscher, P. J. Warner

We use a numerical simulation to investigate the effectiveness of pinhole spatial filters at optical/IR interferometers and to compare them with single-mode optical fibre spatial filters and interferometers without spatial filters. We show that fringe visibility measurements in interferometers containing spatial filters are much less affected by changing see

A. Palacios, C. Charbonnel, M. Forestini

We present a scenario to explain the lithium-rich phase which occurs on the red giant branch at the so-called bump in the luminosity function. The high transport coefficients required to enhance the surface lithium abundance are obtained in the framework of rotation-induced mixing thanks to the impulse of the important nuclear energy released in a lithium bu

P. P. Petrov, J. Pelt, I. Tuominen

The classical T Tauri star RW Aur A is an irregular variable with a large amplitude in all photometric bands. In an extended series of photometric data we found small-amplitude periodic variations in the blue colours of the star, with a period of 2.64 days. The period was relatively stable over several years. The amplitude of the periodic signal is 0.21 mag

M. Kregel, R. Sancisi

The HI structure and kinematics of the peculiar starburst galaxy NGC 3310 (Arp 217, UGC 5786) are discussed. New evidence bearing on the origin of the starburst is presented. The bulk of HI coincides with the bright optical disk and shows differential rotation. Its velocity dispersion is, however, unusually large for a spiral galaxy (up to 40 km/s), suggesti

G. Cayrel de Strobel, C. Soubiran, N. Ralite

The catalogue presented here is a compilation of published atmospheric parameters (Teff, logg, [Fe/H]) obtained from high resolution, high signal-to-noise spectroscopic observations. This new edition has changed compared to the five previous versions. It is now restricted to intermediate and low mass stars (F, G and K stars). It contains 6354 determinations

L. Perivolaropoulos

We investigate the effects of negative pressure induced by dark energy (cosmological constant or quintessence) on the dynamics at various astrophysical scales. Negative pressure induces a repulsive term (antigravity) in Newton's law which dominates on large scales. Assuming a value of the cosmological constant consistent with the recent SnIa data we dete

Gerard A. Kriss

In a survey of the UV-brightest AGN using the Far Ultraviolet Spectroscopic Explorer (FUSE), we commonly find associated absorption in the O VI 1032,1038 resonance doublet. Of 34 Type I AGN observed to date with z < 0.15, 16 show detectable O VI absorption. Most absorption systems show multiple components with intrinsic widths of ~100 km/s spread over a blue

Ariane Lançon, Mustapha Mouhcine

Integrated spectrophotometric properties of stellar systems are intrinsically dispersed due to the stochastic nature of the small numbers of bright stars they contain. Among clusters, only the most massive ones can be used individually for comparison with the mean properties predicted by population synthesis calculations. The appropriate minimal masses depen

R. P. Malik

In the framework of superfield formalism, we discuss some aspects of the cohomological features of a two (1+1)-dimensional free Abelian gauge theory described by a Becchi-Rouet-Stora-Tyutin (BRST) invariant Lagrangian density. We demonstrate that the conserved and nilpotent (anti-)BRST- and (anti-)co-BRST charges are the generators of translations along the

Olaf Lechtenfeld, Alexander D. Popov

The study of noncommutative solitons is greatly facilitated if the field equations are integrable, i.e. result from a linear system. For the example of a modified but integrable U(n) sigma model in 2+1 dimensions we employ the dressing method to construct explicit multi-soliton configurations on noncommutative R^{2,1}. These solutions, abelian and nonabelian

S. N. Dolya, O. B. Zaslavskii

We consider Hamiltonians, which are even polynomials of the forth order with the respect to Bose operators. We find subspaces, preserved by the action of Hamiltonian These subspaces, being finite-dimensional, include, nonetheless, states with an \QTR{it}{infinite} number of quasi-particles, corresponding to the original Bose operators. The basis functions lo

Hiroshi Yaguchi, Takashi Akima, Zhiqiang Mao, Yoshiteru Maeno

We have investigated the ac susceptibility of the spin triplet superconductor Sr$_2$RuO$_4$ as a function of magnetic field in various directions at temperatures down to 60 mK. We have focused on the in-plane field configuration (polar angle $θ\simeq 90^{\circ}$), which is a prerequisite for inducing multiple superconducting phases in Sr$_2$RuO$_4$. We have

Carlton M. Caves, Christopher A. Fuchs, Ruediger Schack

In the Bayesian approach to probability theory, probability quantifies a degree of belief for a single trial, without any a priori connection to limiting frequencies. In this paper we show that, despite being prescribed by a fundamental law, probabilities for individual quantum systems can be understood within the Bayesian approach. We argue that the distinc

Diederik Aerts

We present an analysis of quantum mechanics and its problems and paradoxes taking into account the results that have been obtained during the last two decades by investigations in the field of `quantum structures research&#39;. We concentrate mostly on the results of our group FUND at Brussels Free University. By means of a spin 1/2 model where the quantum p

Diederik Aerts, Jan Broekaert, Sonja Smets

In this article we propose an approach that models the truth behavior of cognitive entities (i.e. sets of connected propositions) by taking into account in a very explicit way the possible influence of the cognitive person (the one that interacts with the considered cognitive entity). Hereby we specifically apply the mathematical formalism of quantum mechani

Erich Novak

It is known that quantum computers yield a speed-up for certain discrete problems. Here we want to know whether quantum computers are useful for continuous problems. We study the computation of the integral of functions from the classical Hoelder classes with d variables. The optimal orders for the complexity of deterministic and (general) randomized methods

D. Podolsky

We discuss the statistical properties of a single vortex line in a perfect fluid. The partition function is calculated up to the end in the thin vortex approximation. It turns out that corresponding theory is renormalizable, and the renormalization law for the core size of the vortex is found. The direction of renormalization group flow makes the thin vortex

Jindrich Zapletal

Whenever I is a projectively generated projectively defined sigma ideal on the reals, if ZFC+large cardinals proves cov(I)=continuum then ZFC+large cardinals proves non(I)<aleph four.

Max Neumann-Coto

Any finite configuration of curves with minimal intersections on a surface is a configuration of shortest geodesics for some Riemannian metric on the surface. The metric can be chosen to make the lengths of these geodesics equal to the number of intersections along them.

Philippe Pouliot

We apply 't Hooft's deterministic quantum mechanics approach to free vector bosons in three dimensions and check Lorentz invariance. This approach does not work for the conformal group, for free bosons in two dimensions. This presents a technical difficulty for constructing a ``deterministic string theory''.

C. E. Aguiar, Y. Hama, T. Kodama, T. Osada

Effects caused by the event-by-event fluctuation of the initial conditions in hydrodynamical description of high-energy heavy-ion collisions are investigated. Non-negligible effects appear for several observable quantities, even for a fixed impact parameter $\vec b $. They are sensitive to the equation of state, being the dispersions of the observable quanti

Fayyazuddin

The decays \bar{B}-> \bar{K}D and \bar{B}-> \bar{K}\bar{D} taking into account final state interactions are discussed. These decays are described by four strong phases δ_0,δ_1,\barδ_0,\barδ_1 (subscripts 0 and 1 refers to I=0 and I=1 final states), one weak phase γand four real amplitudes. It is argued that strong interaction dynamics implies \barδ_1=0,δ_0=-

W. Melnitchouk

We examine the origin of Bloom-Gilman duality and the relationship between resonances and scaling in deep-inelastic scattering. A simple quantum mechanical model is used to illustrate the essential features of Bloom-Gilman duality at low momentum transfer. As an application of local duality, we discuss model-independent relations between structure functions

V. Novikov

The existence of extra chiral generations with all fermions heavier than $m_Z$ is strongly disfavored by the precision electroweak data. However the data still allow a few extra generations if the neutral leptons have masses close to 50 GeV. Such heavy neutrino can be searched in the reaction $e^+ e^- \to N\bar{N}γ$. Existence of 50 GeV neutrinos makes stand

Luca Salasnich

In this report we investigate the macroscopic quantum tunneling of a Bose condensate falling under gravity and scattering on a Gaussian barrier that could model a mirror of far-detuned sheet of light. We analyze the effect of the inter-atomic interaction and that of a transverse confining potential. We show that the quantum tunneling can be quasi-periodic an

Christoph P. Hofmann

We investigate the low-temperature behavior of ferromagnets with a spontaneously broken symmetry O(3) $\to$ O(2). The analysis is performed within the perspective of nonrelativistic effective Lagrangians, where the dynamics of the system is formulated in terms of Goldstone bosons. Unlike in a Lorentz-invariant framework (chiral perturbation theory), where lo

A. van de Walle, G. Ceder

A longstanding limitation of first-principles calculations of substitutional alloy phase diagrams is the difficulty to account for lattice vibrations. A survey of the theoretical and experimental literature seeking to quantify the impact of lattice vibrations on phase stability indicates that this effect can be substantial. Typical vibrational entropy differ

Francoise Combes

The strongest starbursts are observed towards galaxy nuclei, or circumnuclear regions. However in interacting galaxies, star formation is also triggered in overlap regions far from nuclei, in spiral arms and sometimes in tidal tails. What is the relative importance of these starbursts? What kind of starformation is dominating, as a function of redshift? Thes

A. Koptsevich

The Programme and Abstracts booklet of the sixth Conference on &#34;Physics of Neutron Stars&#34; held at the Ioffe Physical Technical Institute, St. Petersburg, Russia, on June 6 -- 8, 2001 is presented. The abstracts contain references to the web pages, LANL archive and published articles. More information on the Conference can be found at http://www.ioffe

S. Borgani, P. Rosati, P. Tozzi, S. A. Stanford

We analyze the ROSAT Deep Cluster Survey (RDCS) to derive cosmological constraints from the evolution of the cluster X-ray luminosity distribution. The sample contains 103 galaxy clusters out to z=0.85 and flux-limit Flim=3 10^{-14} cgs (RDCS-3) in the [0.5-2.0] keV energy band, with a high-z extension containing four clusters at 0.90<z<1.26 and F>1 10^{-14}

Deepto Chakrabarty, Lee Homer, Philip A. Charles, Darragh O&#39;Donoghue

We have detected large-amplitude 0.3-1.2 mHz quasi-periodic oscillations (QPOs) from the low-mass X-ray binary pulsar 4U 1626-67/KZ TrA, using UV photometry from HST and ground-based optical photometry. These 1 mHz QPOs, which have coherence (Nu/DeltaNu)=8, are entirely distinct from the 130 mHz pulsar spin frequency, a previously known 48 mHz QPO, and the 4

M. Magliocchetti, S. J. Maddox, C. A. Jackson, J. Bland-Hawthorn

We use redshift determinations and spectral analysis of galaxies in the 2dF Galaxy Redshift Survey to study the properties of local radio sources with $S\ge 1$ mJy. 557 objects drawn from the FIRST survey, corresponding to 2.3 per cent of the total radio sample, are found in the 2dFGRS cataloge within the area $9^h 48^m \simlt {\rm RA}({\rm 2000}) \simlt 14^

T. Aoyama, K. Ishikawa, N. Maeda

We study striped states in the quantum Hall system around half-filled high Landau levels and obtain the optimal orientation of the striped state in the presence of an external unidirectional periodic potential. It is shown that the optimal orientation is orthogonal to the external modulation in the Coulomb dominant regime (the orthogonal phase) and is parall

Z. Ye

By an improved scaling analysis, we suggest that there may appear two possibilities concerning the electronic localization in two dimensional random media. The first is that all electronic states are localized in two dimensions, as already conjectured previously. The second possibility is that the electronic behaviors in two and three dimensional random syst

L. A. Caron, H. Jirari, H. Kröger, X. Q. Luo

We use the quantum action to study quantum chaos at finite temperature. We present a numerical study of a classically chaotic 2-D Hamiltonian system - harmonic oscillators with anharmonic coupling. We construct the quantum action non-perturbatively and find temperature dependent quantum corrections in the action parameters. We compare Poincaré sections of th

Shannon Starr

In this thesis we present three results about the ferromagnetic quantum XXZ model: 1) Existence of a spectral gap above all infinite-volume ground states in one dimension for any choice of spin S>1/2 (for S=1/2 this was already known); 2) Characterization of one-dimensional &#34;droplet&#34; states as ground states of the spin-1/2 model with up spin boundary

Valerio Toledano-Laredo

We classify and construct all irreducible positive energy representations of the loop group of a compact, connected and simple Lie group and show that they admit an intertwining action of Diff(S^{1}).

Valerio Toledano-Laredo

We show that in the presence of suitable commutator estimates, a projective unitary representation of the Lie algebra of a connected and simply connected Lie group G exponentiates to G. Our proof does not assume G to be finite--dimensional or of Banach-Lie type and therefore encompasses the diffeomorphism groups of compact manifolds. We obtain as corollaries

Azniv Kasparian

The number of the relations of a Kahler group is bounded below by the number of the generators and some geometric invariants of the corresponding compact Kahler manifold, like the irregularity, the Albanese dimension and the Albanese genera. Appropriate functions of the aforementioned geometric invariants are shown to be lower bounds for the Betti numbers of

A. Bossard, N. Mohammedi

The symmetry properties of the bosonic string effective action under Poisson-Lie duality transformations are investigated. A convenient and simple formulation of these duality transformations is found, that allows the reduction of the string effective action in a Kaluza-Klein framework. It is shown that the action is invariant provided that the two Lie algeb

Ichiro Oda

In cases of both abelian and nonabelian gauge groups, we study the Higgs mechanism in the topologically massive gauge theories in an arbitrary space-time dimension. We show that when the conventional Higgs potential coexists with a topological term, gauge fields become massive by &#39;eating&#39; simultaneously both the Nambu-Goldstone boson and a higher-ran

Yuji Koike

Mechanism for the single transverse spin asymmeties in the pion production, p^\uparrow + p&#39;\to π(\ell_T) + X, and the Λhyperon polarization, p + p&#39; \to Λ^\uparrow (\ell_T)+ X, is investigated in the framework of QCD factorization theorem. We identify all the soft-gluon pole contributions coming from the twist-3 distribution and/or fragmentation funct

M. Sami

In this paper we investigate the general features of &#34;Oscillatory Inflation&#34;. In adiabatic approximation, we derive a general formula for the number of e-foldings $\tilde{N}$ which reduces to the standard expression in case of the slow role approximation and leads to the Damour-Mukhanov type expression for the slowly varying adiabatic index. We apply

Vladimir V. Konotop, Victor M. Perez-Garcia

We argue that the classical form of the dipole-dipole interaction energy cannot be used to model the interaction of the bosons in a dilute Bose-Einstein condensate made of polar atoms. This fact is due to convergence of integrals, if no additional restrictions are introduced. The problem can be regularized, in particular, by introducing a hard sphere model.

Juan J. Garcia-Ripoll, Victor M. Perez-Garcia, Vadym Vekslerchik

In this paper we study a general nonlinear Schrödinger equation with a time dependent harmonic potential. Despite the lack of traslational invariance we find a symmetry trasformation which, up from any solution, produces infinitely many others which are centered on classical trajectories. The results presented here imply that, not only the center of mass of

Gunnar Moos, Cornelius Gahl, Roman Fasel, Martin Wolf

Femtosecond time-resolved photoemission of photoexcited electrons in highly oriented pyrolytic graphite (HOPG) provides strong evidence for anisotropies of quasiparticle (QP) lifetimes. Indicative of such anisotropies is a pronounced anomaly in the energy dependence of QP lifetimes between 1.1 eV and 1.5 eV - the vicinity of a saddle point in the graphite ba

S. K. Kwon, S. J. Youn, K. S. Kim, B. I. Min

Based on electronic structure calculations, we have found that noble metal diborides, AgB2 and AuB2, are potential candidates for conventional BCS-type high temperature superconductors. B 2p density of states dominates at the Fermi level in comparison with Ag 4d and Au 5d states. Furthermore, the electron-phonon coupling constant λis much larger in AgB2 and

K. Venu, V. S. S. Sastri, K. P. N. Murthy

We propose a lattice model to simulate the influence of porous medium on the Nematic - Isotropic transition of liquid crystal confined to the pores. The effects of pore size and pore connectivity are modelled through a disorder parameter. Monte Carlo calculations based on the model leads to results that compare well with experiments.

W. C. Wu

Recent ARPES measurement observed a large $ab$-axis gap anisotropy, $Δ(0,π)/Δ(π,0)=1.5$, in clean YBa$_2$Cu$_3$O$_{7-δ}$. This indicates that some sub-dominant component may exist in the $d_{x^2-y^2}$-wave dominant gap. We propose that the interlayer pairing tunneling contribution can be determined through the investigation of the order parameter anisotropy.

T. Joseph W. Lazio, A. L. Fey

We present multi-frequency observations with the Very Long Baseline Array of the compact double radio source B2 2050+36. Our observations are at 0.33, 0.61, 1.67, 2.3, and 8.4 GHz, with the 0.61 GHz observations forming the third epoch of observation of this source at that frequency. At 0.61 GHz, the structure of B2 2050+36 is dominated by two components 56

T. J. Davidge

JHK images with angular resolutions approaching the diffraction limit of the 3.6 meter Canada-France-Hawaii Telescope are used to investigate the bright AGB content of the M31 bulge. The AGB-tip in a field 2.6 arcmin from the galaxy center occurs at K = 15.6, which is significantly fainter than measured in previous ground-based studies that sampled similar p

Francois Legrand, Guillermo Tenorio-Tagle, Sergiy Silich, Daniel Kunth

We construct three extreme different scenarios of the star formation histories applicable to a sample of dwarf galaxies, based either on their present metallicity or their luminosity. The three possible scenarios imply different mechanical energy input rates and these we compare with the theoretical lower limits established for the ejection of processed matt

M. Magliocchetti, S. J. Maddox

We present an analysis of the properties of optical counterparts of radio sources down to 1 mJy. Optical identifications have been obtained by matching together objects from the APM and FIRST surveys over the region $148.13^\circ\simlt {\rm RA(2000)}\simlt 218.13^\circ$, $-2.77^\circ\simlt {\rm Dec} \simlt 2.25^\circ$. Selecting radio sources down to 1 mJy,

C. C. Cheung, D. C. Homan, J. F. C. Wardle, D. H. Roberts

We present a detailed recipe for making movies from multi-epoch radio observations of astronomical sources. Images are interpolated linearly in time to create a smooth succession of frames so that a continuous movie can be compiled. Here, we outline the procedure, and draw attention to specific details necessary for making a successful movie. In particular,

Joseph E. Pesce, Rita M. Sambruna, F. Tavecchio, L. Maraschi

We report the detection at X-rays of the radio/optical jet of 3C 371, from a short (10 ks) Chandra exposure in March 2000. We also present a new MERLIN observation at 1.4 GHz together with a renalysis of the archival HST WFPC2 F555W image. Despite the limited signal-to-noise ratio of the Chandra data, the X-ray morphology is clearly different from that of th

S. Kondratyuk, A. D. Lahiff, H. W. Fearing

We solve the Bethe-Salpeter equation for two-particle scattering in a field-theoretical model using two lagrangians related by a field transformation. The kernel of the equation consists of the sum of all tree-level diagrams for each lagrangian. The solutions differ even if all four external particles are put on the mass shell, which implies that observables

G. Suryan

A New Mathematico-Physical and Information Theoretic Approach Examination of the available hard core information to firm up the process of unification of quantum and gravitational physics leads to the conclusion that for achieving this synthesis, major paradigm shifts are needed as also the answering of `What is Time?&#39; The object of this submission is to

Benson Farb, Lee Mosher

We develop a theory of convex cocompact subgroups of the mapping class group MCG of a closed, oriented surface S of genus at least 2, in terms of the action on Teichmuller space. Given a subgroup G of MCG defining an extension L_G: 1--> pi_1(S) --> L_G --> G -->1 we prove that if L_G is a word hyperbolic group then G is a convex cocompact subgroup of MCG. Wh

S. M. Khairul Alam, Jordi Miralda-Escude

We calculate the neutral hydrogen column density of self-absorption in QSOs predicted in a model where the QSOs are located in the same halos that contain the gas in damped Lya absorption systems. The model is parameterized by the probability P_0 that any halo has an active QSO. We assume that the QSOs ionize the gas, but do not expel or heat it. The derived

Luis M. A. Bettencourt, Krishna Rajagopal, James V. Steele

As the matter produced in a relativistic heavy ion collision cools through the QCD phase transition, the dynamical evolution of the chiral condensate will be driven out of thermal equilibrium. As a prelude to analyzing this evolution, and in particular as a prelude to learning how rapid the cooling must be in order for significant deviations from equilibrium

S. Potting, M. Cramer, P. Meystre

We demonstrate theoretically the use of genetic learning algorithms to coherently control the dynamics of a Bose-Einstein condensate. We consider specifically the situation of a condensate in an optical lattice formed by two counterpropagating laser beams. The frequency detuning between the lasers acts as a control parameter that can be used to precisely man

A. I. Shapovalova, A. N. Burenkov, L. Carrasco, V. H. Chavushyan

We have monitored the AGN 3C390.3 between 1995 and 2000.Two large amplitude outbursts, of different duration, in continuum and H beta light were observed ie.: in October 1994 a brighter flare that lasted about 1000 days and in July 1997 another one that lasted about 700 days were detected. The flux in the H beta wings and line core vary simultaneously, a beh

Christian Zier, Peter L. Biermann

Most galaxies have central massive black holes (BH), and merge with others during their evolution, as strongly suggested by recent observations. Consequently a black hole binary (BHB) emerges. Considering the evolution of the binary when it has become hard, at a separation of the BHs of about 1 pc, we propose to solve two basic questions in our understanding

B. J. Campbell, R. Osborn, D. N. Argyriou, L. Vasiliu-Doloc

A system of strongly-interacting electron-lattice polarons can exhibit charge and orbital order at sufficiently high polaron concentrations. In this study, the structure of short-range polaron correlations in the layered colossal magnetoresistive perovskite manganite, La1.2Sr1.8Mn2O7, has been determined by a crystallographic analysis of broad satellite maxi

Luis Lehner

Computer simulations are enabling researchers to investigate systems which are extremely difficult to handle analytically. In the particular case of General Relativity, numerical models have proved extremely valuable for investigations of strong field scenarios and been crucial to reveal unexpected phenomena. Considerable efforts are being spent to simulate

V. F. Dmitriev, V. Zelevinsky, Sam M. Austin

An eikonal model has been used to assess the relationship between calculated strengths for first forbidden beta decay and calculated cross sections for (p,n) charge exchange reactions. It is found that these are proportional for strong transitions, suggesting that hadronic charge exchange reactions may be useful in determining the spin-dipole matrix elements

P. M. Singer, T. Imai, T. He, M. A. Hayward

We report (13)C NMR characterization of the new superconductor MgCNi_3 (He et al., Nature (411), 54 (2001)). We found that both the uniform spin susceptibility and the spin fluctuations show a strong enhancement with decreasing temperature, and saturate below ~50K and ~20K respectively. The nuclear spin-lattice relaxation rate 1/(13)T_1T exhibits typical beh

Yang Ji, M. Heiblum, Hadas Shtrikman

The complex transmission amplitude -- both magnitude and phase -- of a quantum dot (QD) with Kondo correlation was measured near the unitary limit. Contrary to previous phase measurements, performed far from this limit [Ji et al., Science 290, 779 (2000)], the transmission phase was observed to evolve linearly over a range of about 1.5 pi when the Fermi ener

Dragan Huterer

We study the power of upcoming weak lensing surveys to probe dark energy. Dark energy modifies the distance-redshift relation as well as the matter power spectrum, both of which affect the weak lensing convergence power spectrum. Some dark-energy models predict additional clustering on very large scales, but this probably cannot be detected by weak lensing a

R. Deblock, Y. Noat, B. Reulet, H. Bouchiat

Signature of phase coherence on the electric and magnetic response of non connected Aharonov-Bohm rings is measured by a resonant method at 350 MHz between 20 mK and 500 mK. The rings are etched in a GaAs-AlGaAs heterojunction. Both quantities exhibit a oscillating behaviour with a periodicity consistent with half a flux quantum $Φ_0/2=h/2e$ in a ring. Elect

Ulf H. Danielsson, Alberto Guijosa, Martin Kruczenski

We consider D-brane/anti-D-brane systems at T>0. Starting at the closed string vacuum, we argue that a finite temperature leads to the reappearance of open string degrees of freedom. We also show that, at a sufficiently large temperature, the open string vacuum becomes stable. Building upon this observation and previous work by Horowitz, Maldacena and Stromi

S. Ambrosanio, A. Dedes, S. Heinemeyer, S. Su

We investigate the Higgs boson sector of the Minimal Supersymmetric Standard Model (MSSM) in the framework of the three most prominent soft SUSY-breaking scenarios, mSUGRA, MGMSB and mAMSB. For each scenario, we determine the parameters at the electroweak scale from the set of input variables at higher energy scales (depending on the specific scenario) and e

A. Achahbar, Pedro L. Garrido, J. Marro, Miguel A. Munoz

By performing extensive MonteCarlo simulations we show that the infinitely fast driven lattice gas (IDLG) shares its critical properties with the randomly driven lattice gas (RDLG). All the measured exponents, scaling functions and amplitudes are the same in both cases. This strongly supports the idea that the main relevant non-equilibrium effect in driven l

D. Bruss, C. Macchiavello

We study optimal eavesdropping in quantum cryptography with three-dimensional systems, and show that this scheme is more secure than protocols using two-dimensional states. We generalize the according eavesdropping transformation to arbitrary dimensions, and discuss the connection with optimal quantum cloning.

D. Brecher, P. M. Saffin

We comment on the recent papers by Costa et al and Emparan, which show how one might generate supergravity solutions describing certain dielectric branes in ten dimensions. The ``basic&#39;&#39; such solutions describe either N fundamental strings or N D4-branes expanding into a D6-brane, with topology M^2 x S^5 or M^5 x S^2 respectively. Treating these solu

K. Sumiyoshi, M. Terasawa, G. J. Mathews, T. Kajino

We reanalyze $r$-process nucleosynthesis in the neutron-rich ejecta from a prompt supernova explosion of a low-mass (11 M$_\odot$) progenitor. A pompt explosion is not yet ruled out as a possibility for low-mass supernova progenitors. Moreover, there is mounting evidence that a new $r$-process site may be required. Hence, we assume that a prompt explosion ca

J. Balog, M. Niedermaier, F. Niedermayer, A. Patrascioiu

The quantum field theory describing the massive O(2) nonlinear sigma-model is investigated through two non-perturbative constructions: The form factor bootstrap based on integrability and the lattice formulation as the XY model. The S-matrix, the spin and current two-point functions, as well as the 4-point coupling are computed and critically compared in bot

Chong-Sun Chu, John Madore, Harold Steinacker

We study the one loop dynamics of QFT on the fuzzy sphere and calculate the planar and nonplanar contributions to the two point function at one loop. We show that there is no UV/IR mixing on the fuzzy sphere. The fuzzy sphere is characterized by two moduli: a dimensionless parameter N and a dimensionful radius R. Different geometrical phases can obtained at

Takeo Inami, Yorinori Saito, Masayoshi Yamamoto

We study the UV properties of the three-dimensional ${\cal N}=4$ SUSY nonlinear sigma model whose target space is $T^*(CP^{N-1})$ (the cotangent bundle of $CP^{N-1}$) to higher orders in the 1/N expansion. We calculate the $β$-function to next-to-leading order and verify that it has no quantum corrections at leading and next-to-leading orders.

Mark P. Davidson

A proof is given that if the nonlinear Schrodinger wave function is constrained to have support over only a finite volume in configuration space, then the total energy is bounded from below for either sign of the logarithmic term in the Hamiltonian. It is concluded that the usual assumption about the sign of the logarithmic term made by Bialynicki-Birula and

Y. Fujiwara, M. Kohno, C. Nakamoto, Y. Suzuki

The baryon-baryon interactions for the complete baryon octet (B_8) are investigated in a unified framework of the resonating-group method, in which the spin-flavor SU_6 quark-model wave functions are employed. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon in

Robert Botet, Marek Ploszajczak, Jorge A. Gonzalez

The spherical spin model with infinite-range ferromagnetic interactions is investigated analytically in the framework of non-extensive thermostatics generalizing the Boltzmann-Gibbs statistical mechanics. We show that for repulsive correlations, a new weak-ferromagnetic phase develops. There is a tricritical point separating para, weak-ferro and ferro regime

M. C. Bento, O. Bertolami, N. C. Santos

We study the dynamics of a quintessence model based on two interacting scalar fields. The model can account for the (recent) accelerated expansion of the Universe suggested by astronomical observations. Acceleration can be permanent or temporary and, for both scenarios, it is possible to obtain suitable values for the cosmological parameters while satisfying

Li Gang Jin, Chong Sheng Li

The Yukawa corrections of order ${\cal O}(α_{ew}m_{t(b)}^2/m_W^2)$, ${\cal O}(α_{ew}m_{t(b)}^3/m_W^3)$ and ${\cal O}(α_{ew}m_{t(b)}^4/m_W^4)$ to the width of sbottom decay into lighter stop plus charged Higgs boson are calculated in the Minimal Supersymmetric Standard Model. These corrections depend on the masses of charged Higgs boson and lighter stop, and

Kingman Cheung

We update the global constraint on four-fermion $ee q q$ contact interactions. In this update, we included the published data of H1 and ZEUS for the 94--96 run in the $e^+ p$ mode and the newly published data of H1 for the 1999 run in the $e^- p$ mode. Other major changes are the new LEPII data on hadronic cross sections above 189 GeV, and the atomic parity

Matthias Vojta, Ralf Bulla, Walter Hofstetter

We discuss models of interacting magnetic impurities coupled to a metallic host. If twice the sum of the impurity spins is larger than the total number of host screening channels, the system shows one or more quantum phase transitions where the ground-state spin changes as a function of the inter-impurity couplings. The simplest example is realized by two sp

David Atwood, Amarjit Soni

A method is proposed for the determination of the unitarity angle alpha through tree penguin interference. The modes needed would be of the form B0/B0-bar -> rho0 M and B0/B0-bar -> omega M where M is spin-0 uu-bar/dd-bar meson, for instance M=pi0, eta, eta&#39;,a0 or f0. An analogous method can also determine gamma using M=KS or K_L. The validity of the the

Denes Petz

Variance and Fisher information are ingredients of the Cramer-Rao inequality. We regard Fisher information as a Riemannian metric on a quantum statistical manifold and choose monotonicity under coarse graining as the fundamental property of variance and Fisher information. In this approach we show that there is a kind of dual one-to-one correspondence betwee

M. V. Altaisky, F. P. Filatov

Possible explanation of the 64/20 redundancy of the triplet genetic code based on the assumption of quantum nature of genetic information is proposed.

Robert R. Tucci

In a previous paper, we showed how entanglement of formation can be defined as a minimum of the quantum conditional mutual information (a.k.a. quantum conditional information transmission). In classical information theory, the Arimoto-Blahut method is one of the preferred methods for calculating extrema of mutual information. In this paper, we present a new

Bimalendu Deb, Gershon Kurizki

We analyze atom-atom interactions in optical lattices due to a laser-induced long-range interatomic force which prevails over the usual London-van der-Waals forces. This force, which can be generated by an intense laser field at a wavelength longer than that of the lattice-generating laser, is shown to bind pairs of cold atoms trapped at different lattice si