August 2001 arXiv papers — page 18

Jen-Hsu Chang, Ming-Hsien Tu

The integrability of the generalized Benney hierarchy with three primary fields is investigated from the point of view of two-dimensional topological field theories coupled to gravity. The associated primary free energy and correlation functions at genus zero are obtained via Landau-Ginzburg formulation and the string equation is derived using the twistor co

B. Geyer, D. M"ulsch

It is shown that the dimensional reduction of the N_T=2, D=3 Blau-Thompson model to D=2, i.e., the novel topological twist of N=8, D=2 super Yang-Mills theory, provides an example of a Hodge-type cohomological theory. In that theory the generators of the topological shift, co-shift and gauge symmetry, together with a discrete duality operation, are completel

Carl M. Bender, Stefan Boettcher, H. F. Jones, Peter Meisinger

The spectrum of the Hermitian Hamiltonian ${1\over2}p^2+{1\over2}m^2x^2+gx^4$ ($g>0$), which describes the quantum anharmonic oscillator, is real and positive. The non-Hermitian quantum-mechanical Hamiltonian $H={1\over2}p^2+{1 \over2}m^2x^2-gx^4$, where the coupling constant $g$ is real and positive, is ${\cal PT}$-symmetric. As a consequence, the spectrum

Alex Krasnitz, Yasushi Nara, Raju Venugopalan

The early stages of a relativistic heavy-ion collision are examined in the framework of an effective classical SU(3) Yang-Mills theory in the transverse plane. We compute the initial energy and number distributions, per unit rapidity, at mid-rapidity, of gluons produced in high energy heavy ion collisions. We discuss the phenomenological implications of our

Alexander Yelkhovsky

The effect of a finite nuclear mass on the magnetic moment of the electron bound in the ground state of a hydrogen-like ion is analyzed. Using the exact in Zαexpression for the recoil shift of the energy, I calculate the order (Zα)^4 m/M correction to the electron gyromagnetic ratio. The theoretical uncertainty in the prediction for the experimentally intere

V. Barger, D. Marfatia, K. Whisnant

We discuss options for U.S. long baseline neutrino experiments using upgraded conventional neutrino beams, assuming $L/E_ν$ is chosen to be near the peak of the leading oscillation. We find that for L = 1290 km (FNAL-Homestake) or 1770 km (FNAL-Carlsbad, or BNL-Soudan) it is possible to simultaneously have good $\sin^22θ_{13}$ reach and sgn($δm^2_{31}$) dete

K. S. Babu, R. N. Mohapatra

We show that in a large class of supersymmetric models with spontaneously broken B-L symmetry, neutron--antineutron oscillations occur at an observable level even though the scale of B-L breaking is very high, v_{B-L} ~ 2 x 10^{16} GeV, as suggested by gauge coupling unification and neutrino masses. We illustrate this phenomenon in the context of a recently

J. A. Martins Simoes, Y. A. Coutinho, C. M. Porto

We present a SU(2)_L * SU(2)_R * U(1) left-right symmetric model for elementary particles and their connection with the fermion mass spectrum. New mirror fermions and a minimal set of Higgs particles are proposed. The model can accommodate a consistent pattern for charged and neutral fermion masses as well as neutrino oscillations. The connection between the

Hisakazu Minakata, Hiroshi Nunokawa

We explore as clearly as possible the features of neutrino oscillation which are relevant for measurements of the CP violating Kobayashi-Maskawa phase delta and the sign of \Delta m^2_{13}. We focus on the so called low-energy option and discuss principles for optimizing experimental parameters to measure these two quantities simultaneously. Toward the goal,

D. G. Cerdeno, S. Khalil, C. Munoz

We review the direct detection of supersymmetric dark matter in the light of recent experimental results. In particular, we show that regions in the parameter space of several supergravity scenarios with a neutralino-nucleon cross section of order of $10^{-6}$ pb, i.e., where current dark matter detectors are sensitive, can be obtained. These are scenarios w

CDF Collaboration

We report a study of the decays B0 -> J/psi K(*)0 pi+ pi-, which involve the creation of a u u-bar or d d-bar quark pair in addition to a b-bar -> c-bar(c s-bar) decay. The data sample consists of 110 1/pb of p p-bar collisions at sqrt{s} = 1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. We measure the branching rati

Wolf-Dieter Nowak

Data taking for Run II of the HERMES experiment will start in late 2001 with three main physics objectives for the next 4-5 years: a measurement of transversity distributions, an improved measurement of helicity distributions, and measurements of exclusive reactions to access Generalized Parton Distributions.

S. I. Bityukov, N. V. Krasnikov, V. A. Taperechkina

Results of numerical procedure of constructing confidence intervals for parameter of the Poisson distribution of signal events in the presence of background events with known value of parameter of Poisson distribution are presented. It is shown that the used procedure has both the Bayesian and frequentist interpretations. Also the possibility to construct a

A. E. Asratyan, G. V. Davidenko, A. G. Dolgolenko, V. S. Kaftanov

A method for detecting the transition numu->nutau in long-baseline accelerator experiments, that consists in comparing the far-to-near ratios of the spectra of quasielastic CC events generated by high- and low-energy beams of muon neutrinos, is proposed. The test may be accessible to big calorimeters with muon spectrometry like MINOS, and is limited by stati

Stefan Hollands, Weihua Ruan

The space of continuous states of perturbative interacting quantum field theories in globally hyperbolic curved spacetimes is determined. Following Brunetti and Fredenhagen, we first define an abstract algebra of observables which contains the Wick-polynomials of the free field as well as their time-ordered products, and hence, by the well-known rules of per

J. Socorro

Using technique of supersymmetric quantum mechanics we present new cosmological quantum solution, in the regime for FRW cosmological model using a barotropic perfect fluid as matter field.

J. Socorro, Octavio Cornejo Perez

We present a family of solutions for the axisymmetric Plebanski-Demianski metric and other corresponding reduced metrics. We also present the black hole characteristics using a new set of parameters for Kerr-Newman metric.

D. Baleanu, S. Baskal

The presence of Killing-Yano tensors implies the existence of non-generic supercharges in spinning point particle theories on curved backgrounds. Dual metrics are defined through their associated non-degenerate Killing tensors of valence two. Siklos spacetimes, which are the only non-trivial Einstein spaces conformal to non-flat pp-waves are investigated in

Dmitri Vassiliev

In abstract Yang-Mills theory the standard instanton construction relies on the Hodge star having real eigenvalues which makes it inapplicable in the Lorentzian case. We show that for the affine connection an instanton-type construction can be carried out in the Lorentzian setting. The Lorentzian analogue of an instanton is a spacetime whose connection is me

T. Matos, F. S. Guzman

We present an exact solution of the averaged Einstein's field equations in the presence of two real scalar fields and a component of dust with spherical symmetry. We suggest that the space-time found provides the characteristics required by a galactic model that could explain the supermassive central object and the dark matter halo at once, since one of

Alfonso Rueda, Bernard Haisch, Roh Tung

It has been shown [1,2] that the electromagnetic quantum vacuum makes a contribution to the inertial mass, $m_i$, in the sense that at least part of the inertial force of opposition to acceleration, or inertia reaction force, springs from the electromagnetic quantum vacuum. As experienced in a Rindler constant acceleration frame the electromagnetic quantum v

Joshua Goodman

Maximum entropy models are considered by many to be one of the most promising avenues of language modeling research. Unfortunately, long training times make maximum entropy research difficult. We present a novel speedup technique: we change the form of the model to use classes. Our speedup works by creating two maximum entropy models, the first of which pred

Joshua Goodman

In the past several years, a number of different language modeling improvements over simple trigram models have been found, including caching, higher-order n-grams, skipping, interpolated Kneser-Ney smoothing, and clustering. We present explorations of variations on, or of the limits of, each of these techniques, including showing that sentence mixture model

T. W. Darling, F. Chu, A. Migliori, D. J. thoma

The current work reports on the elastic shear moduli, internal friction, and the specific heat of the B2 cubic ordered alloy AuZn as a function of temperature. Measurements were made on single-crystal and polycrystalline samples using Resonant Ultrasound Spectroscopy (RUS), semi-adiabatic calorimetry and stress-strain measurements. Our results confirm that t

M. M. Deshmukh, S. Gueron, E. Bonet, A. N. Pasupathy

We present detailed measurements of the discrete electron-tunneling level spectrum within nanometer-scale cobalt particles as a function of magnetic field and gate voltage, in this way probing individual quantum many-body eigenstates inside ferromagnetic samples. Variations among the observed levels indicate that different quantum states within one particle

Qing-feng Sun, Hong Guo, Jian Wang

The ac Josephson effect in hybrid systems of a normal mesoscopic conductor coupled to two superconducting (S) leads is investigated theoretically. A general formula of the ac components of time-dependent current is derived which is valid for arbitrary interactions in the normal region. We apply this formula to analyze a S-normal-S system where the normal reg

C. Mitra, P. Raychaudhuri, G. Kobernik, K. Dorr

The hole-doped manganite La0.7Ca0.3MnO3 and the electron-doped manganite La0.7Ce0.3MnO3 undergo an insulator to metal transition at around 250 K, above which both behave as a polaronic semiconductor. We have successfully fabricated an epitaxial trilayer (La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3), where SrTiO3 is an insulator. At room temperature, i.e. in the sem

T. Lofwander, V. S. Shumeiko, G. Wendin

We discuss how life-time broadening of quasiparticle states influences single- and two-particle current transport through zero-energy states at normal metal/d-wave superconductor junctions. We distinguish between intrinsic broadening (imaginary part $η$ of the energy), which couples the bound states with the superconducting reservoir, and broadening due to l

Manuel Cardona

In the past five years enormous progress has been made in the ab initio calculations of the optical response of electrons in semiconductors. The calculations include the Coulomb interaction between the excited electron and the hole left behind, as well as local field effects. However, they are performed under the assumption that the atoms occupy fixed equili

S. Sonoda, S. Shimizu, T. Sasaki, Y. Yamamoto

Wurtzite (Ga,Mn)N films showing ferromagnetic behaviour at room temperature were successfully grown on sapphire(0001) substrates by molecular beam epitaxy using ammonia as nitrogen source. Magnetization measurements were carried out by a superconducting quantum interference device at the temperatures between 1.8K and 300K with magnetic field applied parallel

M. -C. Firpo, S. Ruffo

We consider the class of long-range Hamiltonian systems first introduced by Anteneodo and Tsallis and called the alpha-XY model. This involves N classical rotators on a d-dimensional periodic lattice interacting all to all with an attractive coupling whose strength decays as r^{-alpha}, r being the distances between sites. Using a recent geometrical approach

S. Kramer, G. V. M. Williams

We report the results from a 17O Nuclear Magnetic Resonance (NMR) study of the high temperature superconducting cuprate (HTSC), RuSr2EuCu2O8. This compound has recently been found to exhibit the coexistence of magnetic order and superconductivity. At 9 T, the magnetic order in the RuO2 layers is predominately ferromagnetic. We measured the 17O NMR spectra fr

Ales Omerzu, Madoka Tokumoto, Bosiljka Tadic, Dragan Mihailovic

Critical exponents at the ferromagnetic transition were measured for the first time in an organic ferromagnetic material tetrakis(dimethylamino)ethylene fullerene[60] (TDAE-C$_{60}$). From a complete magnetization-temperature-field data set near $T_{c}=16.1\pm 0.05,$ we determine the susceptibility and magnetization critical exponents $γ=1.22\pm 0.02$ and $β

A. Sherman

The reason for the appearance of two distinct bands in the photoemission of the single CuO$_2$ plane Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+δ}$ near the Fermi level is discussed on the basis of the self-consistent solution of the two-dimensional t-J model.

Nobuhiko Hayashi, Yusuke Kato

The elementary vortex pinning potential is studied in unconventional superconductors within the framework of the quasiclassical theory of superconductivity. Numerical results are presented for d-, anisotropic s-, and isotropic s-wave superconductors to show explicitly that in unconventional superconductors the vortex pinning potential is determined mainly by

M. Pissas, E. Moraitakis, D. Stamopoulos, G. Papavassiliou

We present a modified method of preparation of the new superconductor MgB$_2$. The polycrystalline samples were characterized using x-ray and magnetic measurements. The surface barriers control the isothermal magnetization loops in powder samples. In bulk as prepared samples we always observed symmetric magnetization loops indicative of the presence of a bul

Hikaru Kawamura, Takuya Arimori

Ordering of the geometrically frustrated two-dimensional Heisenberg antiferromagnet on a pyrochlore slab is studied by Monte Carlo simulations. In contrast to the kagomé Heisenberg antiferromagnet, the model exhibits locally non-coplanar spin structures at low temperatures, bearing nontrivial chiral degrees of freedom. Under certain conditions, the model exh

Z. Hu, M. Knupfer, M. S. Golden, J. Fink

We present a systematic study of the perovskite-related system La2-xSrxCu1-yRuyO4 using Cu-L2,3, Ru-L2,3, and O-K x-ray absorption spectroscopy (XAS). This system can be regarded as a solid solution of the two superconductors La2-xSrxCuO4 and Sr2RuO4, and thus the question as to the destination of the holes induced by Sr doping is central to our understandin

R. Gutierrez, G. Fagas, G. Cuniberti, F. Grossmann

We have performed parameter-free calculations of electron transport across a carbon molecular junction consisting of a C$_{60}$ molecule sandwiched between two semi-infinite metallic carbon nanotubes. It is shown that the Landauer conductance of this carbon hybrid system can be tuned within orders of magnitude not only by varying the tube-C$_{60}$ distance,

M. Ebrahim Fouladvand, Nima Hamedani Radja

We propose a stochastic model for the intersection of two urban streets. The traffic state at the crossroads is controlled by a set of traffic lights, which periodically switch to red and green with a total period of T. Vehicular dynamics is simulated and total delay experienced by the traffic is evaluated within a definite time interval. Minimizing the dela

Zheng-Mao Sheng, Guoxiang Huang

We show that non-damped acoustic plasmons exist in single wall carbon nanotubes (SWCNT) and propose that the non-damped acoustic plasmons may mediate electron-electron attraction and result in superconductivity in the SWCNT. The superconducting transition temperature Tc for the SWCNT (3,3) obtained by this mechanism agrees with the recent experimental result

William T. Reach, Jeonghee Rho, T. H. Jarrett, Pierre-Olivier Lagage

New observations of the supernova remnant 3C391 are in the H2 2.12 micron and [Fe II] 1.64 micron narrow-band filters at the Palomar 200-inch telescope, and in the 5-15 micron CVF on ISOCAM. Shocked H2 emission was detected from the region 3C391:BML, where broad millimeter CO and CS lines had previously been detected. A new H2 clump was confirmed to have bro

P. J. McCarthy, R. G. Carlberg, H. -W. Chen, R. O. Marzke

(Abridged) We have identified a population of faint red galaxies from a 0.62 square degree region of the Las Campanas Infrared Survey whose properties are consistent with their being the progenitors of early-type galaxies. The optical and IR colors, number-magnitude relation and angular clustering together indicate modest evolution and increased star formati

G. A. Kriss, J. M. Shull, W. Oegerle, W. Zheng

The neutral hydrogen and the ionized helium absorption in the spectra of quasars are unique probes of structure in the early universe. We present Far-Ultraviolet Spectroscopic Explorer observations of the line of sight to the quasar HE2347-4342 in the 1000-1187 A band at a resolving power of 15,000. We resolve the He II Ly alpha absorption as a discrete fore

Aparna Venkatesan, Mark L. Giroux, J. Michael Shull

Observational studies indicate that the intergalactic medium (IGM) is highly ionized up to redshifts just over 6. A number of models have been developed to describe the process of reionization and the effects of the ionizing photons from the first luminous objects. In this paper, we study the impact of an X-ray background, such as high-energy photons from ea

Y. Yang, A. S. Wilson, P. Ferruit

We present Chandra X-ray observations of the nearby Seyfert 1.5 galaxy NGC 4151. The images show the extended soft X-ray emission on the several hundreds of pc scale with better sensitivity than previously obtained. The spectrum of the unresolved nuclear source may be described by a heavily absorbed (N_{H} \simeq 3 \times 10^{22} cm^-2), hard power-law (Γ\si

C. M. Raiteri, M. Villata, H. D. Aller, M. F. Aller

New optical and radio data on the BL Lacertae object AO 0235+16 have been collected in the last four years by a wide international collaboration, which confirm the intense activity of this source. The optical data also include the results of the Whole Earth Blazar Telescope (WEBT) first-light campaign organized in November 1997. The optical spectrum is obser

P. V. Baev, H. Markov, N. Spassova

The physical parameters of the stars in the central region of the globular cluster M5 (NGC 5904) were determined from UBV photometry using Kurucz (1992) synthetic flux distributions and some empirical relations. It is found that the bluest horizontal branch stars have higher luminosities than predicted by canonical zero-age horizontal branch models. Paramete

C. S. Kochanek

We derive a simple, fast one-dimensional integral for the equatorial rotation curve of a thin disk with surface density Sigma(R) modeled as a spheroid with axis ratio q. The result is simpler than standard expressions even in the limit of an infinitely thin disk (q-->0).

Paul P. van der Werf, Alan F. M. Moorwood, Lin Yan

In this paper we review the present status and implications of H-alpha surveys at various redshifts. With the advent of sensitive wide-format near-infrared detectors on large telescopes, deep and extensive H-alpha surveys are now feasible to redshift z~2.5. The cosmic star formation history can therefore be traced out to this redshift using H-alpha alone, av

C. S. Kochanek

We explore the relationship between the mass function of CDM halos and dynamical probes of the mass function such as the distribution of gravitational lens separations and the local velocity function. The compression of galactic halos by the cooling baryons, a standard component of modern models, leads to a feature in the distribution of lens separations nea

A. Aparicio, R. Carrera, D. Martinez-Delgado

The photometric and morphological properties, as well as the star formation history, of the Draco dwarf spheroidal galaxy are analyzed on the basis of wide field, CCD photometry of the resolved stars covering about 1deg^2. No metallicity gradient is detected. The star surface density distribution can be fitted by a single exponential law of scale-length a=5&

S. Randich

We have measured the equivalent width (EW) of the K I 7699 A line in a sample of G and K-type members of the ~35 Myr old cluster IC 2602 for which a dispersion in Li EWs had been reported by previous studies. Active cluster stars with 0.75 < (B-V)o < 1 are characterized by a dispersion in the EW of the K I 7699 A, while earlier and later-type stars do not sh

Cheongho Han, Chunguk Lee

In this paper, we investigate the properties of the planet-induced deviations in the trajectory of the microlensed source star centroid motion (astrometric curve) and the correlations between the astrometric and photometric deviations. For this, we construct vector field maps of excess centroid shifts. Fromthe investigation of the maps, we find that the astr

J. Bland-Hawthorn, W. van Breugel, P. R. Gillingham, I. K. Baldry

Tunable narrow-band, emission-line surveys have begun to show the ease with which star forming galaxies can be identified in restricted redshift intervals to z ~ 5 with a 4m class telescope. These surveys have been carried out with imaging systems at the Cassegrain or Nasmyth focus and are therefore restricted to fields smaller than 10 arcmin. We now show th

Jason X. Prochaska, Arthur M. Wolfe

We compare new observations on the kinematic characteristics of the damped Lya systems against results from numerical SPH simulations to test the predictions of hierarchical galaxy formation. This exercise is particularly motivated by recent numerical results on the cross-section of damped Lya systems. Our analysis focuses on the velocity widths of ~50 low-i

D. J. Eisenstein, J. Annis, J. E. Gunn, A. S. Szalay

We describe the target selection and resulting properties of a spectroscopic sample of luminous, red galaxies (LRG) from the imaging data of the Sloan Digital Sky Survey (SDSS). These galaxies are selected on the basis of color and magnitude to yield a sample of luminous, intrinsically red galaxies that extends fainter and further than the main flux-limited

R. Reigada, A. Sarmiento, Katja Lindenberg

We study energy relaxation in thermalized one-dimensional nonlinear arrays of the Fermi-Pasta-Ulam type. The ends of the thermalized systems are placed in contact with a zero-temperature reservoir via damping forces. Harmonic arrays relax by sequential phonon decay into the cold reservoir, the lower frequency modes relaxing first. The relaxation pathway for

Elliott Middleton

A two-variable model is developed to forecast the probability of recession in the U.S. economy. Like many others, the model uses data a year or more old to explain movements of a dichotomous dependent variable for recession. The innovation of the present effort is the introduction of a confidence variable, which appears to increase the qualitative accuracy a

Jorgen Rasmussen

A new N=4 superconformal algebra (SCA) is presented. Its internal affine Lie algebra is based on the seven-dimensional Lie algebra su(2)\oplus g, where g should be identified with a four-dimensional non-reductive Lie algebra. Thus, it is the first known example of what we choose to call a non-reductive SCA. It contains a total of 16 generators and is obtaine

Jesus Salas, Shu-Chiuan Chang, Robert Shrock

We present exact calculations of the Potts model partition function $Z(G,q,v)$ for arbitrary $q$ and temperature-like variable $v$ on $n$-vertex square-lattice strip graphs $G$ for a variety of transverse widths $L_t$ and for arbitrarily great length $L_\ell$, with free longitudinal boundary conditions and free and periodic transverse boundary conditions. Th

D. P. Mahapatra, B. Mohanty, S. C. Phatak

The effect of limiting the acceptance in rapidity on event-by-event multiplicity fluctuations in nucleus-nucleus collisions has been investigated. Our analysis shows that the multiplicity fluctuations decrease when the rapidity acceptance is decreased. We explain this trend by assuming that the probability distribution of the particles in the smaller accepta

M. C. Llaguno, J. Hone, A. T. Johnson, J. E. Fischer

The thermal conductivity, k(T), of bulk single-wall carbon nanotubes (SWNT&#39;s) displays a linear temperature dependence at low T that has been attributed to 1D quantization of phonons. To explore this issue further, we have measured the k(T) of samples with varying average tube diameters. We observe linear k(T) up to higher temperatures in samples with sm

Kevin R. Lynch

We look at a number of simple, but representative, models of extended electroweak gauge structures, and present the general contributions to a_muon from the heavy Z&#39; and W&#39; electroweak gauge bosons. Of the models we have examined, none can explain the observed discrepancy between the current experimental value of a_muon and the Standard Model predict

Domenico Tocchini-Valentini, Luca Amendola

We show that all cosmological models with an accelerated stationary global attractor reduce asymptotically to a dark energy field with an exponential potential coupled linearly to a perfect fluid dark matter. In such models the abundance of the dark components reaches a stationary value and therefore the problem of their present coincidence is solved. The re

Gopal-Krishna, Prasad Subramanian, Paul J. Wiita, Peter A. Becker

Using a large set of optically detected hotspots in powerful extragalactic double radio sources, we examine the basic question of whether the detection of optical synchrotron radiation requires in-situ acceleration of relativistic electrons within the hotspots/lobes. For this, we take into account the jet&#39;s bulk relativistic motion, as well as its likely

Nick Evans, Michela Petrini

A chemical potential may be introduced into the AdS/CFT correspondence by setting the D3 branes of the construction spinning. In the field theory the fermionic modes are expected to condense as Cooper pairs, although at zero temperature the chemical potential destabilizes the scalar sector of the N=4 theory obscuring this phenomena. We show, in the case wher

Marco Cavaglia, Alessandro Fabbri

We calculate perturbative quantum gravity corrections to eternal two-dimensional black holes. We estimate the leading corrections to the AdS_2 black hole entropy and determine the quantum modification of N-dimensional Schwarzschild spacetime.

Gilles Tarjus, Victor Dotsenko

In this paper we study the phase diagram of the disordered Ising ferromagnet. Within the framework of the Gaussian variational approximation it is shown that in systems with a finite value of the disorder in dimensions D=4 and D < 4 the paramagnetic and ferromagnetic phases are separated by a spin-glass phase. The transition from paramagnetic to spin-glass s

E. Christova, S. Fichtinger, S. Kraml, W. Majerotto

Analytic expressions for the angular distributions of the $b$-quarks associated with single $t$-quark production in $p \bar p \to W^* \to t \bar b \to b \bar b W$ and of the leptons from the subsequent decay $W \to lν$ are obtained in the laboratory system. CP violation in the $t$-production vertex is assumed. Different angular and total cross section CP vio

Javier Ballesteros-Paredes, Mordecai-M. Mac Low

We examine how well the physical properties of clumps in turbulent molecular clouds can be determined by measurements of observed clump structures. We compare simulated observations of three-dimensional numerical models of isothermal, magnetized, supersonic turbulence to the actual physical structure of the models. We determine how changing the parameters of

Thorsten C. Bschorr, Dietmar G. Fischer, Matthias Freyberger

We analyze the Pauli-channel estimation with mixed nonseparable states. It turns out that within a specific range entanglement can serve as a nonclassical resource. However, this range is rather small, that is entanglement is not very robust for this application. We further show that Werner states yield the best result of all Bell diagonal states with the sa

A. Zurita, J. E. Beckman, M. Rozas, S. Ryder

In this paper we make a quantitative study of the hypothesis that the diffuse H-alpha emitted from the discs of spiral galaxies owes its origin to the ionizing photons escaping from HII regions. We use the H-alpha measurements of the complete set of HII regions in the spiral NGC 157, for which an HI density map was available, to derive a family of models whi

G. Hiller, A. Kagan

Polarized $Λ_b \to Λγ$ decays at the Z pole are shown to be well suited for probing a large variety of New Physics effects. A new observable is proposed, the angular asymmetry between the $Λ_b$ spin and photon momentum, which is sensitive to the relative strengths of the opposite chirality and Standard Model chirality $b \to s γ$ dipole operators. Combinatio

Ioannis Kouletsis, Karel. V. Kuchar

The structure of the history phase space $\cal G$ of a covariant field system and its history group (in the sense of Isham and Linden) is analyzed on an example of a bosonic string. The history space $\cal G$ includes the time map $\sf T$ from the spacetime manifold (the two-sheet) $\cal Y$ to a one-dimensional time manifold $\cal T$ as one of its configurat

Lajos Molnar

We prove that any bijective fidelity preserving transformation on the set of all density operators on a Hilbert space is implemented by an either unitary or antiunitary operator on the underlying Hilbert space.

Celine Reyle, Annie C. Robin, Michel Creze

The interpretation of high proper motion white dwarfs detected by Oppenheimer et al (2001) was the start of a lively controversy. While the discoverers identify a large fraction of their findings as dark halo members, others interpret the same sample as essentially made of disc and/or thick disc stars. We use the comprehensive description of Galactic stellar

M. C. Gonzalez-Garcia, M. Maltoni, C. Peña-Garay

In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultane

Tatsuo Kobayashi, Haruhiko Terao

We study the so-called ``Kaluza-Klein regularization&#39;&#39;. We calculate one-loop corrections to the Higgs mass due to Kaluza-Klein modes explicitly in a model with SUSY breaking mass splitting between bosonic and fermionic modes. We perform the proper time cutoff at $1/Λ^2$ and the KK level truncation at $\ell$. It is shown that the finite result is obt

V. Dzhunushaliev, H. -J. Schmidt, O. Rurenko

The multidimensional gravity on the principal bundle with the SU(2) gauge group is considered. The numerical investigation of the spherically symmetric metrics with the center of symmetry is made. The solution of the gravitational equations depends on the boundary conditions of the ``SU(2) gauge potential&#39;&#39; (off-diagonal metric components) at the sym

D. Bandyopadhyay, C. Bhattacharya, K. Krishan, S. Bhattacharya

Decay sequence of hot ${31}^$P nucleus has been investigated through exclusive light charged particle measurements in coincidence with individual evaporation residues using the reaction ${19}^$F (96 MeV) + ${12}^$C. Information on the sequential decay chain have been extracted by confronting the data with the predictions of the statistical model. It is obser

Aurel Bulgac

I formulate a local density approximation for fermion systems with pairing correlations based on a rapidly converging renormalization scheme for the pairing gap.

Dong Lai, Wynn C. G. Ho

It is known that vacuum polarization can modify the photon propagation modes in the atmospheric plasma of a strongly magnetized neutron star. A resonance occurs when the effect of vacuum polarization on the photon modes balances that of the plasma. We show that a photon (with energy $E\go$ a few keV) propagating outward in the atmosphere can convert from one

G. J. Stephens, Luis M. A. Bettencourt, W. H. Zurek

We examine the formation of vortices during the nonequilibrium relaxation of a high-temperature initial state of an Abelian-Higgs system. We equilibrate the scalar and gauge fields using gauge-invariant Langevin equations and relax the system by instantaneously removing thermal fluctuations. For couplings near critical we observe the formation of large clust

Chr. Wunderlich, Chr. Balzer, P. E. Toschek

A quantum system being observed evolves more slowly. This `&#39;quantum Zeno effect&#39;&#39; is reviewed with respect to a previous attempt of demonstration, and to subsequent criticism of the significance of the findings. A recent experiment on an {\it individual} cold trapped ion has been capable of revealing the micro-state of this quantum system, such t

Don N. Page

The ideas of Sensible Quantum Mechanics are expressed in lay terms for philosophers of consciousness and others. A framework is proposed and explained for the `psycho-physical-parallelism&#39; between conscious experiences and the mathematical structures of quantum physics (e.g., a set of quantum operators obeying some algebra, and a quantum state giving the

W. Struyve, W. De Baere

Recently Ghose (quant-ph/0001024,quant-ph/0003037,quant-ph/0103126) and Golshani and Akhavan (quant-ph/0009040,quant-ph/0103100,quant-ph/0103101) claimed to have found experiments that should be able to distinguish between Standard Quantum Mechanics and Bohmian Mechanics. It is our aim to show that the claims made by Ghose, Golshani and Akhavan are unfounded

Markus A. Cirone, Aldo Delgado, Dietmar G. Fischer, Matthias Freyberger

We investigate the problem of determining the parameters that describe a quantum channel. It is assumed that the users of the channel have at best only partial knowledge of it and make use of a finite amount of resources to estimate it. We discuss simple protocols for the estimation of the parameters of several classes of channels that are studied in the cur

B. A. Grishanin, V. N. Zadkov

Relevance of key quantum information measures for analysis of quantum systems is discussed. It is argued that possible ways of measuring quantum information are based on compatibility/incompatibility of the quantum states of a quantum system, resulting in the coherent information and introduced here the compatible information measures, respectively. A sketch

E. Knill

Fermionic linear optics is efficiently classically simulatable. Here it is shown that the set of states achievable with fermionic linear optics and particle measurements is the closure of a low dimensional Lie group. The weakness of fermionic linear optics and measurements can therefore be explained and contrasted with the strength of bosonic linear optics w

Kaoru Sanaka, Karin Kawahara, Takahiro Kuga

Quantum computers promise great improvements in solving problems such as factoring large integers, simulating quantum systems, and database searching. Using a photon as a quantum bit (qubit) is one of the most promising ways to realize a universal quantum computer because the coherent superposition state of a photon is very robust against various sources of

J. M. Deutsch

Motivation: Microarray data has been recently been shown to be efficacious in distinguishing closely related cell types that often appear in the diagnosis of cancer. It is useful to determine the minimum number of genes needed to do such a diagnosis both for clinical use and to determine the importance of specific genes for cancer. Here a replication algorit

R. I. Khrapko

Rest mass takes the place of inertial mass in modern physics textbooks. It seems to be wrong. But this phenomenon is hidden away by the facts that rest mass adherents busily call rest mass &#34;mass&#34;, not rest mass, and the word &#34;mass&#34; is associated with a measure of inertia. This topic has been considered by the author in the article &#34;What i

J. Lehr, U. Mosel

We discuss several particle production reactions on nuclei within a BUU transport model. After a short presentation of the model we show our results for the transparency ratio for the nucleon knock-out reaction in different nuclei. The influence of the nucleon spectral function on subthreshold particle production is discussed.

M. Post, U. Mosel

We calculate the effect of many-body interactions in nuclear matter on the spectral function of $ρ$ and $ω$ meson. In particular, we focus on the role played by baryon resonances in this context.

A. Leviatan, J. N. Ginocchio

The identification of pseudospin symmetry as a relativistic symmetry of the Dirac Hamiltonian is used to explain the structure of radial nodes occurring in pseudospin doublets and to illuminate the special status of nodeless intruder states in nuclei.

J. A. Niskanen

The effect of isospin breaking pion s-wave rescattering is included in elastic NN scattering at low energies using effective field theory. Although this mechanism gave a large contribution to charge symmetry breaking in np --> d pi0, the effect is rather small in pp vs. nn scattering parameters and in the 3H-3He binding energy difference. This smallness is c

STAR Collaboration, Manuel Calderon de la Barca Sanchez

Negatively charged hadron (h-) production in Au+Au collisions at BNL-RHIC is studied with the STAR experiment. Results are presented on h- multiplicity, pseudorapidity and transverse momentum distributions at sqrt(s_NN) = 130 GeV.

B. B. Back

We present the first measurement of the pseudorapidity density of primary charged particles in Au+Au collisions at sqrt(s_NN) = 200GeV. For the 6% most central collisions, we obtain dN_ch/deta|_|eta|<1 = 650 +/- 35 (syst). Compared to collisions at sqrt(s_NN) = 130GeV, the highest energy studied previously, an increase by a factor of 1.14 +/- 0.05 is found.

J. M. Buldu, J. Trull, M. C. Torrent, J. Garcia-Ojalvo

The dynamics of power distribution between longitudinal modes of a multimode semiconductor laser subjected to external optical feedback is experimentally analyzed in the low-frequency fluctuation regime. Power dropouts in the total light intensity are invariably accompanied by sudden activations of several longitudinal modes. These activations are seen not t