September 2000 arXiv papers — page 5

I. Baraffe, A. Heger, S. E. Woosley

The stability of metal-free very massive stars ($Z$ = 0; $M = 120 - 500 \msol$) is analyzed and compared with metal-enriched stars. Such zero-metal stars are unstable to nuclear-powered radial pulsations on the main sequence, but the growth time scale for these instabilities is much longer than for their metal-rich counterparts. Since they stabilize quickly

A. Arenas, A. Diaz-Guilera, R. Guimera

We present a simple model of communication in networks with hierarchical branching. We analyze the behavior of the model from the viewpoint of critical systems under different situations. For certain values of the parameters, a continuous phase transition between a sparse and a congested regime is observed and accurately described by an order parameter and t

Zhi-zhong Xing

We introduce the commutators of lepton mass matrices to describe the phenomenon of lepton flavor mixing, and establish their relations to the effective Hamiltonians responsible for the propagation of Dirac and Majorana neutrinos. The determinants of those commutators are invariant under matter effects, leading to an instructive relationship between the unive

Masamichi Nishino, Seiji Miyashita

We propose a dynamical mechanism of the two-way switching between the metastable state and the stable state, which has been found in experiments of photoinduced reversible magnetization and photoinduced structural phase transition. We find that the two-way switching with a non-symmetry breaking perturbation such as illumination is possible only in systems wi

R. J. McLure, J. S. Dunlop

The central black-hole masses of a sample of 30 luminous quasars are estimated using H-beta FWHM measurements from a combination of new and previously-published nuclear spectra. The quasar black-hole mass estimates are combined with reverberation-mapping measurements for a sample of Seyfert galaxies (Wandel 1999) in order to study AGN black-hole masses over

Tal Alexander, Abraham Loeb

The effect of stars on the lensing properties of the supermassive black hole in the Galactic Center is similar to the effect of planets on microlensing by a star. We show that the dense stellar cluster around SgrA* increases by factors of a few the probability of high-magnification lensing events of a distant background source by the black hole. Conversely,

Darwin Chang, We-Fu Chang, Chung-Hsien Chou, Wai-Yee Keung

We calculate the dominant contributions to the muon $g-2$ at the two-loop level due to a generic pseudoscalar boson that may exist in any exotic Higgs sector in most extensions of the standard model. The leading effect comes from diagrams of the Barr-Zee type. A sufficiently light pseudoscalar Higgs boson can give rise to contribution as large as the electro

Zurab Kakushadze

We consider an infinite-volume brane world setup where a codimension one brane is coupled to bulk gravity plus a scalar field with vanishing potential. The latter is protected by bulk supersymmetry, which is intact even if brane supersymmetry is completely broken as the volume of the extra dimension is infinite. Within this setup we discuss a flat solution w

S. Glancy, J. M. LoSecco, C. E. Tanner

We show that the optical Kerr effect can be used to construct a quantum phase gate. It is well known from quantum nondemolition techniques that, as two photon field modes pass through a Kerr medium, the phase of each mode will be shifted, and the size of the phase shift will depend on the number of photons in both modes. We discuss the Hamiltonian responsibl

A. Acin, A. Andrianov, E. Jane, R. Tarrach

In this paper we analyze the canonical forms into which any pure three-qubit state can be cast. The minimal forms, i.e. the ones with the minimal number of product states built from local bases, are also presented and lead to a complete classification of pure three-qubit states. This classification is related to the values of the polynomial invariants under

D. G. Angelakis, E. Paspalakis, P. L. Knight

We study the spontaneous emission, the absorption and dispersion properties of a ${\bf Λ}$-type atom where one transition interacts near resonantly with a double-band photonic crystal. Assuming an isotropic dispersion relation near the band edges, we show that two distinct coherent phenomena can occur. First, the spontaneous emission spectrum of the adjacent

D. Leibfried, C. Roos, P. Barton, H. Rohde

Ground state cooling and coherent manipulation of ions in an rf-(Paul) trap is the prerequisite for quantum information experiments with trapped ions. With resolved sideband cooling on the optical S1/2 - D5/2 quadrupole transition we have cooled one and two 40Ca+ ions to the ground state of vibration with up to 99.9% probability. With a novel cooling scheme

Massimiliano F. Sacchi

We present a method for the determination of the completely positive (CP) map describing a physical device based on random preparation of the input states, random measurements at the output, and maximum-likelihood principle. In the numerical implementation the constraint of completely positivity can be imposed by exploiting the isomorphism between linear tra

Luca Marinatto, Tullio Weber

This is a reply to the paper by S.C.Benjamin, quant-ph/0008127.

Kim J. Bostroem

Despite the fact that the fundamental physical laws are symmetric in time, most observed processes do not show this symmetry. Especially the phenomenon of decay seems to involve a kind of irreversibility that makes the definition of a microscopic arrow of time possible. Such an intrinsic irreversibility is incorporated within the Rigged Hilbert Space quantum

William D. Walker

A simple relativistic analysis is presented which shows that near-field superluminal longitudinal electric signals generated by an electric dipole cannot be used to violate Einstein causality by using the relativistic "sync shift" effect. The analysis shows that because a signal has some time extent (i.e. after a signal is initiated one must waitat l

A. Kabel, M. Dohlus, T. Limberg

Coherent synchrotron radiation (CSR) occurs when short bunches travel on strongly bent trajectories. Its effects on high-quality beams can be severe and are well understood qualitatively. For quantitative results, however, one has to rely on numerical methods. There exist several simulation codes utilizing different approaches. We describe in some detail the

J. Schaffner-Bielich

The properties of strange hadrons, i.e. of kaons and hyperons, in the nuclear medium are discussed in connection with neutron star properties and relativistic heavy-ion collisions. Firstly, the relevant medium modifications of a kaon in a medium as provided by heavy-ion collisions is critically examined within a coupled channel calculation. We demonstrate, t

Norman K. Glendenning

Uncertainty of the hyperon couplings, in particular, that of the $Σ^-$, in dense matter raises the question of the behavior of the electrochemical potential in neutron star matter, which is crucial to the possible presence of the kaon condensed phase. We show that regardless of this uncertainty, the $Λ$ hyperon, whose coupling can be constrained by its bindi

V. Baran, M. Colonna, M. Di Toro, M. Zielinska-Pfabe

We discuss the features of instabilities in binary systems, in particular, for asymmetric nuclear matter. We show its relevance for the interpretation of results obtained in experiments and in "ab initio" simulations of the reaction between $^{124}Sn+^{124}Sn$ at 50AMeV.}

M. Di Toro, V. Baran, M. Colonna, S. Maccarone

We show the possibility of extracting important information on the symmetry term of the Equation of State ($EOS$) directly from multifragmentation reactions using stable isotopes with different charge asymmetries. We study n-rich and n-poor $Sn + Sn$ collisions at $50AMeV$ using a new stochastic transport approach with all isospin effects suitably accounted

Dimitri Kusnezov, N. V. Zamfir, R. F. Casten

The predictions of the IBM two-body random ensemble are compared to empirical results on nuclei from Z=8 to 100. Heretofore unrecognized but robust empirical trends are identified and related both to the distribution of valence nucleon numbers and to the need for and applicability of specific, non-random interactions. Applications to expected trends in exoti

Dimitri Kusnezov

The two-body random ensemble (TBRE) for a many-body bosonic theory is mapped to a problem of random polynomials on the unit interval. In this way one can understand the predominance of 0+ ground states, and analytic expressions can be derived for distributions of lowest eigenvalues, energy gaps, density of states and so forth. Recently studied nuclear spectr

L. Alvarez-Ruso

A simple model for the n p -> d pi pi reaction has been developed. It is shown that the deuteron momentum spectra measured at T_n = 795 MeV can be understood in terms of the Roper excitation and its N pi pi decay modes. A similar pattern, recently observed in p p -> p p pi+ pi-, can be explained in the same way.

A. Voinov, M. Guttormsen, E. Melby, J. Rekstad

The gamma-ray strength function for gamma energies in the 1-7 MeV region has been measured for 161,162-Dy and 171,172-Yb using the (3-He,alpha gamma) reaction. Various models are tested against the observed gamma-ray strength functions. The best description is based on the Kadmenskii, Markushev and Furman E1 model with constant temperature and the Lorentzian

G. Boffetta, I. M. Sokolov

We investigate Lagrangian relative dispersion in direct numerical simulation of two-dimensional inverse cascade turbulence. The analysis is performed by using both standard fixed time statistics and an exit time approach. Our results are in good agreement with the original Richardson's description in terms of diffusion equation. The deviations are only o

Weiqiang Wang

We give a geometric realization of the symmetric algebra of the tensor space $C^n \bigotimes C^m$ together with the action of the dual pair $(gl_n, gl_m)$ in terms of lagrangian cycles in the cotangent bundles of certain varieties. We establish geometrically the equivalence between the $(gl_n, gl_m)$ duality and Schur duality. We establish the connection bet

Jinho Baik, Eric M. Rains

We present a number of results relating partial Cauchy-Littlewood sums, integrals over the compact classical groups, and increasing subsequences of permutations. These include: integral formulae for the distribution of the longest increasing subsequence of a random involution with constrained number of fixed points; new formulae for partial Cauchy-Littlewood

Lev Glebsky, Gelasio Salazar

It has been long congectured that the crossing number of $C_m\times C_n$ is $(m-2)n$ for $2<m<=n$. In this paper we proved that conjecture is true for all but finitely many $n$ for each $m$. More specifically we proved conjecture for $n>=(m/2)((m+3)^2/2+1)$.The proof is largely based on the theory of arrangements introduced by Adamsson and further developed

Leonid Polterovich

A theorem of Moser guarantees that every diffeomorphism of a closed manifold can be isotoped to a volume preserving one. We show that this statement cannot be extended into contact category: some connected components of contactomorphism groups of certain contact manifolds contain no volume-preserving diffeomorphisms. This phenomenon can be considered from di

O. F. B. van Koert, M. Lubke

The Horrocks-Mumford bundle $E$ is a famous stable complex vector bundle of rank 2 on 4-dimensional complex projective space. By construction, $E$ has a natural Hermitian metric $h_1$. On the other hand, stability implies the existence of a Hermitian-Einstein metric in $E$ which is unique up to a positive scalar. Now the obvious question is if $h_1$ is in fa

M. R. Razvan

Let $ϕ^t$ be a continuous flow on a metric space $X$ and $I$ be an isolated invariant set with an index pair $(N,L)$ and a Morse decomposition $\{M_i\}^n_{i=1}$. For every category $ν$ on $N/L$, we prove that $ν(N/L)\leq ν([L])+\sum_{i=1}^n ν(M_i)$. As a result if $ϕ^t|_I$ is gradient-like and $X$ is semi-locally contractible, then $ϕ^t$ has at least $ν_H(h(

Morihiko Saito

We give an explicit formula for the exponents (i.e. the spectra up to the shift by one) of an irreducible plane curve singularity in terms of Puiseux pairs. As an application we prove in this case Hertling&#39;s conjecture that the variance (i.e. the square of the standard deviation) of the exponents is bounded by the difference between the maximal and minim

Radu Tatar

It has been conjectured that a pair of D5 - anti D5 branes wrapped on some non-trivial two cycle of a Calabi-Yau manifold becomes a stable BPS D3 brane in the presence of a very large B field and magnetic fluxes on their worldvolumes. We discuss this by considering the non-commutative field theory on the worldvolume of the pair of branes whose field multipli

P. Olesen, K. Zarembo

A previous calculation of the phase transition in the Wilson loop correlator in the zero temperature AdS/CFT correspondence is extended to the case where the loops are concentric circles of unequal radii. This phase transition occurs due to the instability of the classical string stretched between the loops. We compute the string action and its expansion in

Ulrika Magnea

I reply to the comment by Dr S. Nishigaki (hep-th/0007042) to my papers Phys. Rev. D61 (2000) 056005 and Phys. Rev. D62 (2000) 016005.

Alexander Gorsky, Konstantin Selivanov

Fate of branes in external fields is reviewed. Spontaneous creation of the Brane World in $AdS_{5}$ with external field is described. The resulting Brane World consists of a flat 4d spatially finite expanding Universe and curved expanding &#34;regulator&#34; branes. All branes have a positive tension.

Alexander Gorsky

The behaviour of the chiral condensates in the SU(2) gauge theory with broken N=2 supersymmetry is reviewed. The calculation of monopole, dyon, and charge condensates is described. It is shown that the monopole and charge condensates vanish at the Argyres-Douglas point where the monopole and charge vacua collide. This phenomenon is interpreted as a deconfine

E. Alvarez, C. Gomez

We review the geometric definition of C-function in the context of field theories that admit a holographic gravity dual.

Shin&#39;ichi Nojiri, Sergei D. Odintsov

We review (mainly) quantum effects in the theories where gravity sector is described by metric and dilaton. The one-loop effective action for dilatonic gravity in two and four dimensions is evaluated. Renormalization group equations are constructed. The conformal anomaly and induced effective action for 2d and 4d dilaton coupled theories are found. It is app

Alexander Cardona

From a path integral point of view (e.g. \cite{Q98}) physicists have shown how {\it duality} in antisymmetric quantum field theories on a closed space-time manifold $M$ relies in a fundamental way on Fourier Transformations of formal infinite-dimensional volume measures. We first review these facts from a measure theoretical point of view, setting the import

Roberto Emparan

After a brief review of the description of black holes on branes, we examine the evaporation of a small black hole on a brane in a world with large extra dimensions. We show that, contrary to previous claims, most of the energy is radiated into the modes on the brane. This raises the possibility of observing Hawking radiation in future high energy colliders

Robert Helling

We study the problem of more general kinematics for the finite N M(atrix)-Model than the simple straight line motion that has been used before. This is supposed to be related to momentum transferring processes in the dual super-gravity description. We find a negative result for classical, perturbative processes and discuss briefly the possibility of instiant

E. J. Ferrer

The Ritus&#39; $E_{p}$ eigenfunction method is extended to the case of spin-1 charged particles in a constant electromagnetic field and used to calculate the one-loop neutrino self-energy in the strong-field approximation $m_{e}^{2}\ll eB\ll M_{W}^{2}$. The implications of the obtained results for neutrino oscillations in the early Universe, assuming the exi

Vivian de la Incera

A discussion of the influence of boundaries and scalar field interactions in the non-perturbative dynamics of fermions in an external magnetic field, along with their possible applications to condensed matter and cosmology, is briefly presented. The significance of the results for electroweak baryogenesis in the presence of an external magnetic field is indi

P. Golonka, E. Richter-Was, Z. Was

We present the system for versioning two packages: the TAUOLA of tau lepton decay and PHOTOS for radiative corrections in decays. The following features can be chosen in automatic or semi-automatic way: (1) format of the common block HEPEVT; (2) version of the physics input (for TAUOLA): as published, as initialized by CLEO collaboration, as initialized by A

S. M. H. Wong

The importance of the color octet component in P-wave charmonia is discussed in the context of exclusive decay processes. It is vital to include this contribution already at the level of the two-body decay channels. The ππand proton-antiproton channels are used as examples.

A. Adamov, Gary R. Goldstein

Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. The resulting $Λ_b$ production rate and polarization at LEP energies are in agreement with experiment. The $Λ_c$ and $Ξ_c$ functions are al

Valery A. Khoze, Wolfgang Ochs, J. Wosiek

We review the perturbative approach to multiparticle production in hard collision processes. It is investigated to what extent parton level analytical calculations at low momentum cut-off can reproduce experimental data on the hadronic final state. Systematic results are available for various observables with the next-to-leading logarithmic accuracy (the so-

Rainer Jakob

The relation of generalized (skewed) quark distributions to nucleon wave functions is discussed in the context of light-cone quantization.

C. F. Berger, B. Jäger, W. Schweiger

We present predictions for differential cross sections for the reaction $γp \to Φp$ and give an outlook to which extent our calculations may be generalized to the photoproduction of $J/Ψ$ mesons. Our results are obtained within perturbative QCD treating the proton as a quark-diquark system.

S. Arunagiri

The two important issues concerning the theory of inclusive decays are studied: (1) evaluation of expectation values of four-quark operators in order to systematically include the spectator effects and (2) estimation of duality breaking corrections in heavy quark expansion. Our study leads to the theoretical prediction of the ratio of lifetimes of $Λ_b$ and

R. Aloisio, V. Azcoiti, G. Di Carlo, A. Galante

We study unquenched lattice SU(2) at nonzero chemical potential at strong coupling and with eight flavours of Kogut-Susskind fermions. Introducing a diquark source term we analyze the behaviour of different types of fermion condensates. Using a non standard approach we can obtain results at zero external source without extrapolations. We find strong evidence

Harry N. Nelson

We discuss recent CLEO results on D0-D0bar and B0d-B0dbar mixing. The principal results are that for the D0 system, allowing for CP violations, the mixing amplitude x&#39;<2.9% (95% C.L.), and for the B0d system, chi=0.198+-0.013+-0.014. We make projections for future sensistivity to D0-D0bar mixing, and to sin(2*beta+gamma).

Andrew Bazarko

MiniBooNE is preparing to search for nu_mu to nu_e oscillations at Fermilab. The experiment is designed to make a conclusive statement about LSND&#39;s neutrino oscillation evidence. We give a status report on the preparation of the experiment and outline the experimental prospects.

E787, :, S. Adler, M. Aoki

The first search for the decay K^+ -> pi^+ pi^0 nu nubar has been performed with the E787 detector at BNL. Based on zero events observed in the kinematical search region defined by 90 MeV/c < P_{pi^+} < 188 MeV/c and 135 MeV < E_{pi^0} < 180 MeV, an upper limit B(K^+ -> pi^+ pi^0 nu nubar) < 4.3 x 10^{-5} at 90% confidence level is established.

F. Palla

I will review the measurements of the $b$-quark mass performed by ALEPH and DELPHI. A large set of observables has been used together with detailed studies on jet algorithms. Very clear effects due to the $b$-quark mass running are observed. Comparing with the determinations at the $Υ(4S)$ threshold, the measurements of the running $b$-quark mass at the $Z$

Bruce Allen, Adrian C. Ottewill

We obtain general formulae for the plus- and cross- polarized waveforms of gravitational radiation emitted by a cosmic string loop in transverse, traceless (synchronous, harmonic) gauge. These equations are then specialized to the case of piecewise linear loops, and it is shown that the general waveform for such a loop is a piecewise linear function. We give

T. Dereli, O. Sarioglu

We give a general class of exact solutions to the (1+2)-dimensional topologically massive gravity model coupled with Maxwell-Chern-Simons theory where a &#34;self-duality&#34; condition is imposed on the Maxwell field.

N. Andersson, G. L. Comer

We present a general formalism to treat slowly rotating general relativistic superfluid neutron stars. As a first approximation, their matter content can be described in terms of a two-fluid model, where one fluid is the neutron superfluid, which is believed to exist in the core and inner crust of mature neutron stars, and the other fluid represents a conglo

G. H. Haroutyunian

Physically admissible choice of the &#34;essential&#34; coordinates identified with components of the metric tensor and co-moving frame of reference reduced to the formulation of the stationary axisymmetric GR problem. Such nontraditional approach allows to obtain new 4-parametric vacuum solution. In special static case this solution becomes the set well-kno

Jeroen van Dongen

In his search for a unified field theory that could undercut quantum mechanics, Einstein considered five dimensional classical Kaluza-Klein theory. He studied this theory most intensively during the years 1938-1943. One of his primary objectives was finding a non-singular particle solution. In the full theory this search got frustrated and in the x^5-indepen

Simona Cocco, Remi Monasson

Most decision and optimization problems encountered in practice fall into one of two categories with respect to any particular solving method or algorithm: either the problem is solved quickly (easy) or else demands an impractically long computational effort (hard). Recent investigations on model classes of problems have shown that some global parameters, su

H. Saleur, U. Weiss

In the weak backscattering limit, point contact tunneling between quantum Hall edges is well described by a Poissonian process where Laughlin quasiparticles tunnel independently, leading to the unambiguous measurement of their fractional charges. In the strong backscattering limit, the tunneling is well described by a Poissonian process again, but this time

Walter Rantner, Xiao-Gang Wen

Motivated by recent experimental measurements of the tunneling characteristics of high T_{c} materials using scanning tunneling spectroscopy, we have calculated the IV and differential conductance curves in the superconducting state at zero temperature. Comparing the two results obtained via BCS-like d-wave pairing and the SU(2) slave boson approach, we find

V. V. Godlevsky, K. M. Rabe

A detailed examination of the energy landscape, density of states and magnetic moment of tetragonally distorted ferromagnetic Ni_2MnGa was performed using first-principles local-spin-density (LSD) pseudopotential calculations, varying V as well as c/a. The energy of tetragonal Ni_2MnGa is found to be nearly constant for values of c/a over a wide range, with

W. G. van der Wiel, S. De Franceschi, T. Fujisawa, J. M. Elzerman

We observe a strong Kondo effect in a semiconductor quantum dot when a small magnetic field is applied. The Coulomb blockade for electron tunneling is overcome completely by the Kondo effect and the conductance reaches the unitary-limit value. We compare the experimental Kondo temperature with the theoretical predictions for the spin-1/2 Anderson impurity mo

Arne Jacobs, Reiner Kümmel

The rise and decay in space and time of a supercurrent in a superconductor between two normal current leads connected to a reservoir is computed with the help of quasiparticle wavepackets which suffer Andreev scattering in the interfaces between the normal current leads and the superconductor. Stills from a computer movie visualize electron <-> hole scatteri

Christian Knetter, Alexander Buehler, Erwin Mueller-Hartmann, Goetz S. Uhrig

We study an extended Shastry-Sutherland model for SrCu_2(BO_3)_2 and analyze the low lying parts of the energy spectrum by means of a perturbative unitary transformation based on flow equations. The derivation of the 1-magnon dispersion (elementary triplets) is discussed. Additionally, we give a quantitative description (symmetries and energies) of bound sta

Christian Knetter, Erwin Mueller-Hartmann, Goetz S. Uhrig

We investigate the one-triplet dispersion in a modified Shastry-Sutherland Model for SrCu_2(BO_3)_2 by means of a series expansion about the limit of strong dimerization. Our perturbative method is based on a continuous unitary transformation that maps the original Hamiltonian to an effective, energy quanta conserving block diagonal Hamiltonian H_{eff}. The

Fabrizio Lillo, Rosario N. Mantegna

We investigate the variety of a portfolio of stocks in normal and extreme days of market activity. We show that the variety carries information about the market activity which is not present in the single-index model and we observe that the variety time evolution is not time reversal around the crash days. We obtain the theoretical relation between the squar

Sumiyoshi Abe, A. K. Rajagopal

Macroscopic thermodynamics of equilibrium is constructed for systems obeying power-law canonical distributions. With this, the connection between macroscopic thermodynamics and microscopic statistical thermodynamics is generalized. This is complementary to the Gibbs theorem for the celebrated exponential canonical distributions of systems in contact with a h

Sumiyoshi Abe, A. K. Rajagopal

The Levy-type distributions are derived using the principle of maximum Tsallis nonextensive entropy both in the full and half spaces. The rates of convergence to the exact Levy stable distributions are determined by taking the N-fold convolutions of these distributions. The marked difference between the problems in the full and half spaces is elucidated anal

Mai Suan Li

New definitions of the structural susceptibilities based on the fluctuations of distances to the native state of toy protein models are proposed. The calculation of such susceptibilities does not require the basin of native state and the folding temperature can be defined from their peak if the native conformation is compact. The number of peaks in the deriv

R. Blaauwgeers, V. B. Eltsov, M. Krusius, J. Ruohio

Superfluid 3He-A displays the largest variety in vortex structure among the presently known coherent quantum systems. The experimentally verified information comes mostly from NMR measurements on the rotating fluid, from which the order-parameter texture can often be worked out. The various vortex structures differ in the topology of their order-parameter fi

D. A. Head

It is argued that systems whose elements are renewed according to an extremal criterion can generally be expected to exhibit long-term memory. This is verified for the minimal extremally driven model, which is first defined and then solved for all system sizes N\geq2 and times t\geq0, yielding exact expressions for the persistence R(t)=[1+t/(N-1)]^{-1} and t

Reinhold Brueckner

We show the inconsistency of the argument linking the integral quantum Hall effect to gauge invariance. The inconsistency mainly consists of equating gauge and real vector potential transformations for a particular system geometry. Correct handling gives no Hall quantization.

Mukunda P. Das, Frederick Green

Shot noise is not normally evident in bulk solid-state conductors, since it is strongly attenuated by inelastic collisions. The ``anomalous&#39;&#39; emergence of macroscopic shot noise is discussed in G. Gomila and L. Reggiani, Phys. Rev. B 62, 8068 (2000). We remark on the consistency of this linear diffusive model at the large voltages and currents needed

J. D. Lee, T. Mizokawa, A. Fujimori

Photoemission in the system of linear charged chains has been studied with the dipole matrix incorporated, from which its dependencies on the photoelectron momentum (${\bf k}$), photon polarization ($\hat{\bf E}$), and photon energy ($ω$) can be explored. The used model is the three-dimensional array of noninteracting chains, which is so simple as to allow a

C. Piermarocchi, F. Tassone

Presence of bound pairs (excitons) in a low-temperature electron-hole plasma is accounted for by including correlation between fermions at the ladder level. Using a simplified one-dimensional model with on-site Coulomb interaction, we calculate the one-particle self-energies, chemical potential, and optical response. The results are compared to those obtaine

A. Georges, O. Parcollet, S. Sachdev

We describe the interplay of quantum and thermal fluctuations in the infinite-range Heisenberg spin glass. This model is generalized to SU(N) symmetry, and we describe the phase diagram as a function of the spin S and the temperature T. The model is solved in the large N limit and certain universal critical properties are shown to hold to all orders in 1/N.

M. Trippenbach, K. Goral, K. Rzazewski, B. A. Malomed

We identify all possible classes of solutions for two-component Bose-Einstein condensates (BECs) within the Thomas-Fermi (TF) approximation, and check these results against numerical simulations of the coupled Gross-Pitaevskii equations (GPEs). We find that they can be divided into two general categories. The first class contains solutions with a region of o

V. S. Khrapai, E. V. Deviatov, A. A. Shashkin, V. T. Dolgopolov

We study the transport properties of the two-dimensional electron gas in AlGaAs/GaAs heterostructures in parallel to the interface magnetic fields at low temperatures. The magnetoresistance in the metallic phase is found to be positive and weakly anisotropic with respect to the orientation of the in-plane magnetic field and the current through the sample. At

Mukunda P Das, Frederick Green

There has been renewed interest in the physics of the so-called crossover for current fluctuations in mesoscopic conductors, most recently involving the possibility of its appearance in the passage to the macroscopic limit. Shot noise is normally absent from solid-state conductors in the large, and its anomalous resurgence there has been ascribed to a rich i

Renato A. Dupke, Joel N. Bregman

We report the results of spatially resolved X-ray spectroscopy of 8 different ASCA pointings distributed symmetrically around the center of the Perseus cluster. The outer region of the intracluster gas is roughly isothermal, with temperature ~ 6-7 keV, and metal abundance ~ 0.3 Solar. Spectral analysis of the central pointing is consistent with the presence

E. I. Chiang, M. K. Joung, M. J. Creech-Eakman, C. Qi

We improve upon the radiative, hydrostatic equilibrium models of passive circumstellar disks constructed by Chiang & Goldreich (1997). New features include (1) account for a range of particle sizes, (2) employment of laboratory-based optical constants of representative grain materials, and (3) numerical solution of the equations of radiative and hydrostatic

Roman Scoccimarro, H. M. P. Couchman

We present a fitting formula for the non-linear evolution of the bispectrum in CDM models, obtained from measurements in high resolution numerical simulations. The formula interpolates between the perturbative and highly non-linear regimes, and generalizes previous results obtained for scale-free initial conditions.

L. Van Waerbeke, T. Hamana, R. Scoccimarro, S. Colombi

As pointed out in previous studies, the measurement of the skewness of the convergence field $κ$ will be useful in breaking the degeneracy among the cosmological parameters constrained from weak lensing observations. The combination of shot noise and finite survey volume implies that such a measurement is likely to be done in a range of intermediate scales (

Sangwook Park, Ken Ebisawa

The diffuse X-ray background (DXB) emission near the Galactic plane ($l,b \sim 25.6^{\circ},0.78^{\circ}$) has been observed with $ASCA$. The observed region is toward a Galactic molecular cloud which was recently reported to cast a deep X-ray shadow in the 0.5 $-$ 2.0 keV band DXB. The selection of this particular region is intended to provide a constraint

Ying Xiong, Paul J. Wiita, Gang Bao

The possibility that some of the observed X-ray and optical variability in active galactic nuclei and galactic black hole candidates is produced in accretion disks through the development of a self-organized critical state is reconsidered. New simulations, including more complete calculations of relativistic effects, do show that this model can produce light

Artie P. Hatzes, William D. Cochran, Barbara McArthur, Sallie L. Baliunas

High precision radial velocity (RV) measurements spanning the years 1980.8--2000.0 are presented for the nearby (3.22 pc) K2 V star $ε$ Eri. These data, which represent a combination of six independent data sets taken with four different telescopes, show convincing variations with a period of $\approx$ 7 yrs. A least squares orbital solution using robust est

A. Markowitz, R. Edelson

Data from the first three years of RXTE observations have been systematically analyzed to yield a set of 300 day, 2-10 keV light curves with similarly uniform, ~5 day sampling, for a total of nine Seyfert 1 galaxies. This is the first X-ray variability survey to consistently probe time scales longer than a few days in a large number of AGN. Comparison with A

Carlos Allende Prieto

A most desirable feature of a standard candle to estimate astronomical distances is robustness against changes in metallicity and age. It is argued that the radii of main sequence stars with spectral types from solar to A0 show predictable changes with metallicity, and detectable changes with evolution. Such stars populate the solar neighborhood, and therefo

Leticia Carigi, Gustavo Bruzual

Photometric properties of stellar populations that evolve according to chemical evolution models developed by Carigi, Colin, & Peimbert (1999) and Carigi & Peimbert (2001) are explored. Models explain the oxygen abundance and gas mass fraction of irregular galaxies NGC 1560, I Zw 18, NGC 2366, and a typical irregular galaxy. The photometric predictions help

W. Jaffe, M. N. Bremer, P. P. van der Werf

We have taken K-band spectra covering 7 cooling flow clusters. The spectra show many of the 1-0S transitions of molecular Hydrogen, as well as some of the higher vibrational transitions, and some lines of ionized Hydrogen. The line ratios allow us to conclude that the rotational states of the first excited vibrational state are in approximate LTE, so that de

Antoine Letessier-Selvon

Observation of Ultra High Energy Cosmic Rays (UHECR) -whose energy exceeds $10^20$eV- is still a puzzle for modern astrophysics. The transfer of more than 16 Joules to a microscopic particle can hardly be achieved, even in the most powerful cosmic accelerators such as AGN&#39;s, GRB&#39;s or FR-II radio galaxy lobes. Potential sources must also lie within 10

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod

We present a ~ 5-yr optical light curve of the recurrent Be/X-ray transient A0538-66 obtained as a by-product of the MACHO Project. These data reveal both a long-term modulation at P = 420.8 +/- 0.8 d and a short-term modulation at 16.6510 +/- 0.0022 d which, within errors, confirms the previously found orbital period. Furthermore, the orbital activity is on

Alvaro Dominguez

A hydrodynamic formulation of the evolution of large-scale structure in the Universe is presented. It relies on the spatially coarse-grained description of the dynamical evolution of a many-body gravitating system. Because of the assumed irrelevance of short-range (``collisional&#39;&#39;) interactions, the way to tackle the hydrodynamic equations is essenti

J. F. Zhou, D. R. Jiang, X. Y. Hong, T. Venturi

Five compact radio sources, include 0420-014, 1334-127, 1504-166, 2243-123, and 2345-167, were observed at 5GHz by European VLBI (Very Long Baseline Interferometry) Network (EVN) in June, 1996. The primary purpose of this observation was to confirm their superluminal proper motions. Here, the results of 1334-127, 1504-166, 2243-123 and 2345-167 are presented

Sonja Vrielmann, Axel D. Schwope

We present a new mapping algorithm, the &#34;Accretion Stream Mapping (ASM)&#34; which uses the full phase-coverage of a light curve to derive spatially resolved intensity distributions along the accretion stream in magnetic cataclysmic variables of AM Herculis type (polars). The surface of the accretion stream is approximated as a duodecadon shaped tube. Af