August 2000 arXiv papers — page 7

Susumu Hirose

S. Gervais gave a finite presentation for the mapping class group of a surface (math.GT/9811162). We show this presentation without using Wajnryb's simple presentation. We use a complex of curves defined by Harvey, in place of Hatcher and Thurston's complex.

Alexandre Soloviev

We develop a theory of non-unitary set-theoretical solutions to the Quantum Yang-Baxter equation. Our results generalize those obtained by Etingof, Schedler and the author. We remark that some of our constructions are similar to constructions obtained by Lu, Yan and Zhu.

Jean Alexandre, Janos Polonyi

The renormalization group method is a successive integration over the fluctuations which are ordered according to their length scale, a parameter in the external space. A different procedure is described, where the fluctuations are treated in a successive manner, as well, but their order is given by an internal space parameter, their amplitude. The different

Ilka Brunner, Volker Schomerus

A large class of D-branes in Calabi-Yau spaces can be constructed at the Gepner points using the techniques of boundary conformal field theory. In this note we develop methods that allow to compute open string amplitudes for such D-branes. In particular, we present explicit formulas for the products of open string vertex operators of untwisted A-type branes.

Pedro F. Gonzalez-Diaz

Within the spirit of five-dimensional gravity in the Randall-Sundrum scenario, in this paper we consider cosmological and gravitational implications induced by forcing the spacetime metric to satisfy a Misner-like symmetry. We first show that in the resulting Misner-brane framework the Friedmann metric for a radiation dominated flat universe and the Schwarzs

Eric R. Sharpe

In this short note we briefly review some recent developments in understanding discrete torsion. Specifically, we give a short overview of the highlights of a group of recent papers which give the basic understanding of discrete torsion. Briefly, those papers observe that discrete torsion can be completely understood simply as the choice of action of the orb

K. V. Shajesh

We attempt to evaluate the effective Lagrangian for a classical background field interacting with the vacuum of two quantum fields. The integration of one of the quantum fields in general leads to a non-local term in the effective Lagrangian and thus becomes intractable during the integration of the other quantum field. We show that $ϕF \tilde{K}$ interactio

Erik Verlinde

The holographic principle is studied in the context of a $n+1$ dimensional radiation dominated closed Friedman-Robertson-Walker (FRW) universe. The radiation is represented by a conformal field theory with a large central charge. Following recent ideas on holography, it is argued that the entropy density in the early universe is bounded by a multiple of the

Carlos Castro, M. S. El Naschie, J. Mahecha

This paper has been withdrawn

Alan R. White

The appearance of the U(1) anomaly in the interactions of reggeized gluons is described. Also discussed is the crucial role the anomaly can play in providing the non-perturbative properties necessary for a transition from gluon and quark reggeon diagrams to hadron reggeons and a reggeon field theory description of the pomeron.

A. H. Mueller, D. N. Triantafyllopoulos

The double well oscillator is used as a QCD-like model for studying the relationship between large order graphs and the instanton-antiinstanton solution. We derive an equation for the perturbative coefficients of the ground state energy when the number of 3 and/or 4-vertices is fixed and large. These coefficients are determined in terms of an exact``bounce&#

R. Buras, D. V. Semikoz

Oscillations of active to sterile neutrinos with a small mixing angle sin 2 θ< 10^{-2} could generate a large lepton asymmetry in the Early Universe. The final order of magnitude of the lepton asymmetry ηis mainly determined by its growth in the last stage of evolution, the so called power-law regime. There exist two contradictory results in the literature,

Dmitri Melikhov, Berthold Stech

We calculate the form factors for weak decays of $B_{(s)}$ and $D_{(s)}$ mesons to light pseudoscalar and vector mesons within a relativistic dispersion approach based on the constituent quark picture. This approach gives the form factors as relativistic double spectral representations in terms of the wave functions of the initial and final mesons. The form

Miroslav Pardy

The power spectrum of the synchrotron radiation generated by the motion of a two-body charged system in an accelerator is derived in the framework of the Schwinger source theory. The final formula can be used to verify the Lorentz length contraction of the two-body system moving in the synchrotron.

Osamu Yasuda

Analyis of the Superkamiokande atmospheric neutrino data is presented in the framework of four neutrinos without imposing constraints of Big Bang Nucleosynthesis. Implications to long baseline experiments are briefly discussed.

T. S. Biro, P. Levai, J. Zimanyi

In a simplified model we study the hadronization of quark matter in an expanding fireball, in particular the approach to a final hadronic composition in equilibrium. Ideal hadron gas equilibrium constrained by conservation laws, the fugacity parametrization, as well as linear and non-linear coalescence approaches are recognized as different approximations to

Roman G. Shulyakovsky

Two-dimensional Abelian Higgs model is considered. It is shown that Higgs mechanism of the gauge bosons masses generating is broken in presence of instantons. It is supposed that discussion can be generalized into the standard model of electroweak interactions.

Otto C. W. Kong

We review an efficient formulation of the complete theory of supersymmetry without R-parity, where all the admissible R-parity violating terms incorporated. Some interesting recent results will be discussed, including newly identified 1-loop contributions to neutrino masses and electric dipole moments of neutron and electron, resulted from R-parity violating

Christopher M. Cormack

Measurements of Deep-Inelastic Neutral and Charged current interactions are presented in lepton proton scattering at HERA. The measurements are obtained from taken during 1996 to 1999 and consists of $30 \rm{pb^{-1}}$ of $e^+p$ and $16 \rm{pb^{-1}}$ of $e^-p$ data. The addition of the new high statistics electron data with the positron data allows the first

K. Gounder, L. Cremaldi

We study the charge correlations between charm mesons produced in 500 GeV pi- N interactions and the charged pions produced closest to them in phase space. With 110,000 fully reconstructed D mesons from experiment E791 at Fermilab, the correlations are studied as functions of the D-pi - D mass difference and of Feynman x. We observe significant correlations

The BABAR Collaboration, B. Aubert

Data collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC are used to study the lifetimes of the B^0 and B^+ mesons. The data sample consists of 7.4 fb-1 collected near the Y(4S) resonance. B^0 and B^+ mesons are fully reconstructed in several exclusive hadronic decay modes to charm and charmonium final states. The B lifetimes are det

Marc Favata

It is well known that, when an external general relativistic (electric-type) tidal field E(t) interacts with the evolving quadrupole moment I(t) of an isolated body, the tidal field does work on the body (``tidal work&#39;&#39;) -- i.e., it transfers energy to the body -- at a rate given by the same formula as in Newtonian theory: dW/dt = -1/2 E dI/dt. Thorn

Brian Roark, Eugene Charniak

Very little attention has been paid to the comparison of efficiency between high accuracy statistical parsers. This paper proposes one machine-independent metric that is general enough to allow comparisons across very different parsing architectures. This metric, which we call ``events considered&#39;&#39;, measures the number of ``events&#39;&#39;, however

Brian Roark, Eugene Charniak

Generating semantic lexicons semi-automatically could be a great time saver, relative to creating them by hand. In this paper, we present an algorithm for extracting potential entries for a category from an on-line corpus, based upon a small set of exemplars. Our algorithm finds more correct terms and fewer incorrect ones than previous work in this area. Add

R de Sousa, G G Cabrera

We study the effect of hole hopping in a doped antiferromagnet described by the `t-J&#39; model, using exact analytic solutions for small clusters. In spite of the small size, they reveal interesting details about the magnetic order, which are not apparent in Mean Field treatments or in numerical calculations. The 4-site cluster with one hole yields the most

Eugene B. Kolomeisky

We derive the equations of hydrodynamics of a fully polarized electron gas placed in a strong magnetic field. These equations reveal the existence of solitons - immobile or propagating domain wall-like defects whose plane is perpendicular to the field direction. The solitons are used to construct weakly excited states, and novel nonuniform persistent current

Katharina Vollmayr-Lee, Kirill Katsov, John D. Weeks

The structure of a uniform simple liquid is related to that of a reference fluid with purely repulsive intermolecular forces in a self-consistently determined external reference field (ERF) phi_ R. The ERF can be separated into a harshly repulsive part phi_ R0 generated by the repulsive core of a reference particle fixed at the origin and a more slowly varyi

J. L. DuBois, H. R. Glyde

Several properties of trapped hard sphere bosons are evaluated using variational Monte Carlo techniques. A trial wave function composed of a renormalized single particle Gaussian and a hard sphere Jastrow function for pair correlations is used to study the sensitivity of condensate and non-condensate properties to the hard sphere radius and the number of par

C. D. Batista, J. Eroles, M. Avignon, B. Alascio

Using the Lanczos method in linear chains we study the double exchange model in the low concentration limit, including an antiferromagnetic super-exchange K. In the strong coupling limit we find that the ground state contains ferromagnetic polarons whose length is very sensitive to the value of K/t. We investigate the dispersion relation, the trapping by imp

J. Kierfeld, H. Nordborg, V. M. Vinokur

We develop a theory for plastic flux creep in a topologically disordered vortex solid phase in type-II superconductors. We propose a detailed description of the plastic vortex creep of the dislocated, amorphous vortex glass in terms of motion of dislocations driven by a transport current $j$. The {\em plastic barriers} $U_{pl}(j)\propto j^{-μ}$ show power-la

V. V. Ryazanov, V. A. Oboznov, A. Yu. Rusanov, A. V. Veretennikov

We report measurements of the temperature dependence of the critical current in Josephson junctions consisting of conventional superconducting banks of Nb and a weakly ferromagnetic interlayer of a Cu$_x$Ni$_{1-x}$ alloy, with $x$ around 0.5. With decreasing temperature $I_c$ generally increases, but for specific thicknesses of the ferromagnetic interlayer,

David Saad, Yoshiyuki Kabashima, Tatsuto Murayama

We employ the methods of statistical physics to study the performance of Gallager type error-correcting codes. In this approach, the transmitted codeword comprises Boolean sums of the original message bits selected by two randomly-constructed sparse matrices. We show that a broad range of these codes potentially saturate Shannon&#39;s bound but are limited d

Debasis Dan, Mangal C. Mahato, A. M. Jayannavar

Transport properties of overdamped Brownian paricles in a rocked thermal ratchet with space dependent friction coefficient is studied. By tuning the parameters, the direction of current exhibit multiple reversals, both as a function of the thermal noise strength as well as the amplitude of rocking force. Current reversals also occur under deterministic condi

K. Dawson, G. Foffi, M. Fuchs, W. Gotze

The transition from a liquid to a glass in colloidal suspensions of particles interacting through a hard core plus an attractive square-well potential is studied within the mode-coupling-theory framework. When the width of the attractive potential is much shorter than the hard-core diameter, a reentrant behavior of the liquid-glass line, and a glass-glass-tr

Massimo Marchiori, Vito Latora

The Small-World phenomenon, popularly known as six degrees of separation, has been mathematically formalized by Watts and Strogatz in a study of the topological properties of a network. Small-worlds networks are defined in terms of two quantities: they have a high clustering coefficient C like regular lattices and a short characteristic path length L typical

I. L. Drichko, A. M. Diakonov, I. Yu. Smirnov, A. I. Toropov

The absorption coefficient for surface acoustic wave $Γ$ and variation in the wave velocity $ΔV/V$ were measured in GaAs/AlGaAs heterostructures; the above quantities are related to interaction of the wave with two-dimensional electron gas and depend nonlinearly on the power of the wave. Measurements were performed under conditions of the integer quantum Hal

T. Kreer, J. Baschnagel, M. Mueller, K. Binder

We present data of Monte Carlo simulations for monodisperse linear polymer chains in dense melts with degrees of polymerization between N=16 and N=512. The aim of this study is to investigate the crossover from Rouse-like dynamics for short chains to reptation-like dynamics for long chains. To address this problem we calculate a variety of different quantiti

Tetsuro Saso

The two-particle-self-consistent theory is applied to the single-impurity Anderson model. It is found that it cannot reproduce the small energy scale in the strong correlation limit. A modified scheme to overcome this difficulty is proposed by introducing an appropriate vertex correction explicitly. Using the same vertex correction, the self-energy is invest

X. S. Ling, S. R. Park, B. A. McClain, S. M. Choi

We report the first observation of a striking history dependence of the structure function of the vortex matter in the peak effect regime in a Nb single crystal by using small angle neutron scattering combined with {\it in situ} magnetic susceptibility measurements. Metastable phases of vortex matter, supercooled vortex liquid and superheated vortex solid, h

J. Links, A. Foerster

A multiparametric extension of the anisotropic U model is discussed which maintains integrability. The R-matrix solving the Yang-Baxter equation is obtained through a twisting construction applied to the underlying Uq(sl(2|1)) superalgebraic structure which introduces the additional free parameters that arise in the model. Three forms of Bethe ansatz solutio

J. Goryo, M. Sigrist

In a quasi-two-dimensional $ p $-wave superconductor there find six Cooper pairing states which are degenerate within the weak-coupling approach. We show that this degeneracy can be lifted by feedback effect favoring the so-called chiral $ p $-wave state. This effect is based on the anomalous coupling between charge and current in a system with broken time r

I. E. Mazets

We investigate collective excitations of an atomic Bose-Einstein condensate in a recently discovered regime [D.O&#39;Dell et al., Phys. Rev. Lett. 84, 5687 (2000)] of a balance between electromagnetically induced $1/r$ attraction and a short-range interatomic repulsion. The corresponding frequencies for monopole, dipole, and quadrupole modes are calculated n

N. Benitez, J. L. Sanz, E. Martinez-Gonzalez

Gravitational lensing predicts an enhancement of the density of bright, distant QSOs around foreground galaxies. We measure this QSO-galaxy correlation w_qg for two complete samples of radio-loud quasars, the southern 1Jy and Half-Jansky samples. The existence of a positive correlation between z~1 quasars and z~0.15 galaxies is confirmed at a p=99.0% signifi

Sergio Molinari, Alberto Noriega-Crespo, Luigi Spinoglio

The two spectrometers on board the Infrared Space Observatory were used to observe the Herbig-Haro objects HH 80, 81 and 80N, as well as their candidate exciting source IRAS 18162-2048. The fine structure lines of [OI]63um, [OI]145um and [CII]158um are detected everywhere, while [NII]122um and [OIII]88um are only detected toward the HH objects; line ratios c

Jose A. Pons, Juan A. Miralles, M. Prakash, James M. Lattimer

We present simulations of the evolution of a proto-neutron star in which kaon-condensed matter might exist, including the effects of finite temperature and trapped neutrinos. The phase transition from pure nucleonic matter to the kaon condensate phase is described using Gibbs&#39; rules for phase equilibrium, which permit the existence of a mixed phase. A ge

P. Kaaret, H. L. Marshall, T. L. Aldcroft, D. E. Graessle

The young pulsar PSR B0540-69 was one of the first targets observed with the Chandra X-Ray Observatory. The high angular resolution of Chandra allows us to resolve the compact nebula surrounding the pulsar. We have determined a position for PSR B0540-69 of R.A. = 05h 40m 11s.221, decl. = -69o 19&#39; 54&#34;.98 (J2000) with a 1-sigma radial uncertainty of 0.

V. L. Sarajedini, R. L. Gilliland, M. M. Phillips

We present results from a study to detect variable galaxies in the Hubble Deep Field North. The goal of this project is to investigate the number density of AGN at z=1 through the detection of variable galaxy nuclei. The advantage of HST is the ability to do accurate photometry within smaller apertures, thus allowing us to probe much lower AGN/host galaxy lu

W. Q. Sumner, E. E. Vityaev

The dependence of luminosity distance on observed resdhift and the cosmological parameters H and q is derived for a contracting Friedmann universe with no cosmological constant. The result is consistent with recent supernovae observations.

Michel Boer, Bruce Gendre

We applied cosmological and absorption corrections to the X-ray and optical afterglow fluxes of a sample of Gamma-Ray Burst sources of known distance. We find a good correlation in X-rays and that the GRBs in our sample form two well defined classes. We tentatively interpret them as radiative and adiabatic afterglow behaviours in the framework of the firebal

E. Depagne, V. Hill, N. Christlieb, F. Primas

We report on the first high spectral resolution analysis of extremely metal-poor halo stars from the Hamburg/ESO objective-prism survey (HES). The spectra were obtained with UVES at VLT-UT2. The two stars under investigation (\object {HE 1303--2708} and \object {HE 1353--2735}) are main-sequence turnoff-stars having metal abundances of [Fe/H]=-2.85 and -3.20

Bertrand Goldman, Eros Collaboration

Since 1996 EROS 2 has surveyed 440 square degrees at high Galactic latitude in order to search for high proper motion stars in the Solar neighbourhood. We present here the analysis of 250 square degrees for which we have three years of data. No object with halo-like kinematics has been detected. Using a detailed Monte-Carlo simulation of the observations, we

Stepan G. Mashnik

A brief survey of nuclide abundances in the solar-system and in cosmic rays and of the believed mechanisms of their synthesis is given. The role of spallation processes in nucleosynthesis is discussed. A short review of recent measurements, compilations, calculations, and evaluations of spallation cross sections relevant to nuclear astrophysics is given as w

B. E. J. Pagel

Chemical evolution of galaxies brings together ideas on stellar evolution and nucleosynthesis with theories of galaxy formation, star formation and galaxy evolution, with all their associated uncertainties. In a new perspective brought about by the Hubble Deep Field and follow-up investigations of global star formation rates, diffuse background etc., it has

C. L. Carilli, G. K. Miley, H. Rottgering, J. Kurk

We summarize observations of the properties of powerful radio galaxies and their environments from z = 0 to 5. These data show that some high redshift radio galaxies inhabit regions of gas and galaxy over-densities indicative of proto-cluster environments.

Yoshiaki Taniguchi, Yasuhiro Shioya

We propose a possible new model for the formation of chain galaxies at high redshift. Our model is summarized as follows. Step I: Successive merging of subgalactic gas clumps results in the formation of a galaxy with a mass of $10^{11-12} M_\odot$ at redshift $z \sim 5$. Step II: Subsequently, supernova explosions occur inside the galaxy and then blow out as

T. Kirsch, R. Baade, D. Reimers

IUE observations of the eclipsing binary system HR 6902 obtained at various epochs spread over four years indicate the presence of warm circumstellar material enveloping the G9 IIb primary. The spectra show Si IV and C IV absorption up to a distance of 3.3 giant radii (R_g}. Line ratio diagnostics yields an electron temperature of ~ 78000 K which appears to

Masahiro Takada, Toshifumi Futamase

We present quantitative investigations of the weak lensing effect on the two-point correlation functions of local maxima (hotspots), $\xipk(θ)$, in the cosmic microwave background (CMB) maps. The lensing effect depends on the projected mass fluctuations between today and the redshift $z_{\rm rec}\approx1100$. If adopting the Gaussian assumption for the primo

R. Teixeira, C. Ducourant, M. J. Sartori, J. I. B. Camargo

We present proper motion measurements of pre-main sequence (PMS) stars associated with major star-forming regions of the southern hemisphere (Chamaeleon, Lupus, Upper Scorpius - Ophiuchus, Corona Australis), situated in the galactic longitude range l = 290\degr to l = 360\degr. A list of PMS stars as complete as possible was established based on the Herbig a

G. Rigolin

A generalized uncertainty relation for an entangled pair of particles is obtained if we impose a symmetrization rule for all operators that we should use when doing any calculation using the entangled wave function of the pair. This new relation reduces to Heisenberg&#39;s uncertainty relation when the particles have no correlation and suggests that we can h

Z. Y. Weng, V. N. Muthukumar, D. N. Sheng, C. S. Ting

The motion of a single hole in a Mott antiferromagnet is investigated based on the t-J model. An exact expression of the energy spectrum is obtained, in which the irreparable phase string effect [Phys. Rev. Lett. 77, 5102 (1996)] is explicitly present. By identifying the phase string effect with spin backflow, we point out that spin-charge separation must ex

C. D. Batista, G. Ortiz, A. V. Balatsky

We present a unified description of the resonance peak and low-energy incommensurate response observed in high-$T_c$ cuprate superconductors. We argue that both features have a purely magnetic origin and they represent universal features of an incommensurate spin state both below and above the superconducting transition temperature. In this description the r

Shahida Dar

We review the status of the electric dipole moment (EDM) of neutron in the Standard Model (SM). The contributions of the strong and electroweak interactions are discussed seperately. In each case the structure of the Lagrangian and the sources of CP violation are specified, and calculational details are given subsequently. These two contributions to the neut

Kristen Menou, Eliot Quataert

We consider the combined role of the thermal ionization, magneto-rotational and gravitational instabilities in thin accretion disks around supermassive black holes. We find that in the portions of the disk unstable to the ionization instability, the gas remains well coupled to the magnetic field even on the cold, neutral branch of the thermal limit cycle. Th

Carole A. Haswell, Andrew R. King, James R. Murray, Philip A. Charles

We propose a mechanism for the superhump modulations observed in optical photometry of at least two black hole X-ray transients (SXTs). As in extreme mass-ratio cataclysmic variables (CVs), superhumps are assumed to result from the presence of the 3:1 orbital resonance in the accretion disc. This causes the disc to become non-axisymmetric and precess. Howeve

James M. Cline, Hassan Firouzjahi

We present the 5-dimensional cosmological solutions in the Randall-Sundrum warped compactification scenario, using the Goldberger-Wise mechanism to stabilize the size of the extra dimension. Matter on the Planck and TeV branes is treated perturbatively, to first order. The back-reaction of the scalar field on the metric is taken into account. We identify the

Guenter Sigl, Diego Torres, Luis Anchordoqui, Gustavo Romero

We study the correlation between compact radio quasars or 3EG gamma-ray blazars and the arrival directions of cosmic rays above 10^19 eV using an updated list of air shower detections. Our Monte Carlo simulations reveal no significant correlations above random and some previous positive results appear to be an effect of the small sample size. Consequently, u

P. Di Bari, R. Foot, R. R. Volkas, Y. Y. Y. Wong

We comment on the recent paper by A. D. Dolgov, S. H. Hansen, S. Pastor and D. V. Semikoz (DHPS) [Astropart. Phys. {\bf 14}, 79 (2000)] on the generation of neutrino asymmetries from active-sterile neutrino oscillations. We demonstrate that the approximate asymmetry evolution equation obtained therein is an expansion, up to a minor discrepancy, of the well-e

Eric R. Sharpe

In this paper we analyze discrete torsion in perturbative heterotic string theory. In previous work we have given a purely mathematical explanation of discrete torsion as the choice of orbifold group action on a B field, in the case that d H = 0; in this paper, we perform the analogous calculations in heterotic strings where d H is nonzero.

Xavier Calmet, Harald Fritzsch

We consider a model for the electroweak interactions based on the assumption that physical particles are singlets under the gauge group SU(2). The concept of complementarity explains why the standard model works with such an extraordinary precision although the fermions and bosons of the model can be viewed as composite objects of some more fundamental fermi

D. C. Cabra, A. De Martino, A. Honecker, P. Pujol

Hubbard chains with periodically modulated coupling constants in a magnetic field exhibit gaps at zero temperature in their magnetic and charge excitations in a variety of situations. In addition to fully gapped situations (plateau in the magnetization curve and charge gap), we have shown [cond-mat/9908398] that plateaux also appear in the presence of massle

L. Mikaelyan

Recent studies of atmospheric neutrinos and the results from CHOOZ and Palo-Verde experiment call for new and more sensitive searches for neutrino oscillations at reactors. The main goal of the project considered here is to look for very small mixing angle oscillations of electron neutrinos in the atmospheric neutrino mass parameter region around Δm^2 ~3 10^

Yu. S. Kalashnikova, A. V. Nefediev

The spectrum of B and D mesons (including the low lying orbitally and radially excited states) is calculated using the quark-antiquark Hamiltonian derived from QCD in the einbein field formalism. Spin-spin and spin-orbit terms due to the confinement and OGE interactions are taken into account as perturbations. Results for the masses and splittings are confro

P. I. Fomin, Yu. V. Shtanov

We consider a spacetime formed by several pieces having common timelike boundary which plays the role of a junction between them. We establish junction conditions for fields of various spin and derive the resulting laws of wave propagation through the junction, which turn out to be quite similar for fields of all spins. As an application, we consider the cas

Y. Nakaoka

The two-step contribution to the spin-longitudinal and the spin-transverse cross sections of ^{12}C,^{40}Ca(p,n) reactions at 494 MeV and 346 MeV is calculated. We use a plane-wave approximation and evaluate the relative contributions from the one-step and the two-step processes. We found that the ratios of the two-step to the one-step processes are larger i

W. F. Kao, Guey-Lin Lin, Jie-Jun Tseng

We reexamine the process $γ\to e^++ e^-$ in a background magnetic field comparable to $B_c\equiv m_e^2/e$. This process is known to be non-perturbative in the magnetic-field strength. However, it can be shown that the {\it moments} of the above pair production width is proportional to the derivatives of photon polarization function at the zero energy, which

Wen-Jui Huang

A system of N two-dimensional weakly interacting bosons in a harmonic trap is considered. When the two-particle potential is a delta function Smith and Wilkin have analytically proved that the elementary symmetric polynomials of particle coordinates measured from the center of mass are exact eigenstates. In this study, we point out that their proof works equ

P. Zhuang, Z. Yang

The pion production by sigma decay and its relation with chiral symmetry restoration in a hot and dense matter are investigated in the framework of the Nambu-Jona-Lasinio model. The decay rate for the process sigma -> 2pion to the lowest order in a 1/N_c expansion is calculated as a function of temperature T and chemical potential mu. The thermal and nonther

R. W. Rendell, A. K. Rajagopal

A single quantum dissipative oscillator described by the Lindblad equation serves as a model for a nanosystem. This model is solved exactly by using the ambiguity function. The solution shows the features of decoherence (spatial extent of quantum behavior), correlation (spatial scale over which the system localizes to its physical dimensions), and mixing (mi

Johann Summhammer

As physics searches for invariants in observations, this paper looks for invariants of probabilistic observation without assuming physical structure. Structure emerges from the basic assumption of science that new information shall lead to more accurate knowledge of the invariants. This leads to statistically unique random variables for expressing observed i

Ian C. Percival

Experiments over three decades have been unable to demonstrate weak nonlocality in the sense of Bell unambiguously, without loopholes. The last important loophole remaining is the detection loophole, which is being tackled by at least three experimental groups. This letter counters five common beliefs about Bell experiments, and presents alternative scenario

D. Ludwin, Y. Ben-Aryeh, A. Mann

We discuss complementarity and uncertainty in a gedanken Which-Way (Welcher-Weg) experiment in a Mach-Zehnder interferometer. Although a Welcher-Weg measurement can be performed with only a negligible amount of momentum change in the detector itself, the change in the interference pattern must correspond to a change in the momentum distribution of the partic

Xijia Miao

A simple method is proposed to prepare conveniently the effective pure state |00...0><0...00| with any number of qubits in a quantum ensemble. The preparation is based on the temporal averaging (Knill, Chuang, and Laflamme, Phys.Rev.A 57, 3348(1998)). The quantum circuit to prepare the effective pure state is designed in a unified and systematical form and i

M. W. Jack, J. J. Hope

A numerical method of calculating the non-Markovian evolution of a driven atom radiating into a structured continuum is developed. The formal solution for the atomic reduced density matrix is written as a Markovian algorithm by introducing a set of additional, virtual density matrices which follow, to the level of approximation of the algorithm, all the poss

S. Panzeri, S. R. Schultz

We demonstrate that the information contained in the spike occurrence times of a population of neurons can be broken up into a series of terms, each of which reflect something about potential coding mechanisms. This is possible in the coding r{é}gime in which few spikes are emitted in the relevant time window. This approach allows us to study the additional

H. Ao, Y. Iwashita, T. Shirai, A. Noda

The high power test model of biperiodic L-support disk-and- washer was fabricated. Among some trouble in the fabrication, the main one was a vacuum leak in a brazing process. The repair test of the leak showed a good result; four units were recovered out of five leak units (recover rate 80%). While an accelerating mode frequency was tuned at an operating fre

L. Doolittle, T. Goulding, D. Oshatz, A. Ratti

The Front End of the Spallation Neutron Source (SNS) extends from the Ion Source (IS), through a 65 keV LEBT, a 402.5 MHz RFQ, a 2.5 MeV MEBT, ending at the entrance to the DTL. The diagnostics suite in this space includes stripline beam position and phase monitors (BPM), toroid beam current monitors (BCM), and an emittance scanner. Provision is included for

I. Reichel, Y. Cai

The sextupole magnets in the Low Energy Ring (LER) of PEP-II are grouped in pairs with a phase advance of 180 degrees. Displacing the magnets or moving the orbit to displace the beam in the magnets in an antisymmetric way creates a dispersion wave around the ring. This can be used to correct the vertical dispersion in LER without changing the local coupling.

Savely G. Karshenboim

We present a brief overview of precision tests of bound state QED and mainly pay our attention to laser spectroscopy as an appropriate tool for these tests. We particularly consider different precision tests of bound state QED theory based on the laser spectroscopy of optical transitions in hydrogen, muonium and positronium and related experiments.

Ionel Lazanu, Sorina Lazanu

The utilisation of crystalline semiconductor materials as detectors and devices operating in high radiation environments, at the future particle colliders, in space applications, in medicine and industry, makes necessary to obtain radiation harder materials. Diamond, SiC and different AIIIBV compounds (GaAs, GaP, InP, InAs, InSb) are possible competitors for

C. M. Celata

The world Heavy Ion Fusion (HIF) Program for inertial fusion energy is looking toward the development and commissioning of several new experiments. Recent and planned upgrades of the facilities at GSI, in Russia, and in Japan greatly enhance the ability to study energy deposition in hot dense matter. Worldwide target design developments have focused on non-i

K. Nakayama, J. Haidenbauer, J. Speth

The reactions p+n-->d+omega and p+n-->d+phi are studied within a relativistic meson-exchange model of hadronic interactions. Predictions for the total cross sections and for the angular distributions of the vector mesons are presented. The resulting cross sections near threshold are around 10 - 30 microb for p+n-->d+omega$ and 200 - 250 nb for p+n-->d+phi. A

B. Pasquini, S. Scherer, D. Drechsel

We study low-energy virtual Compton scattering off the proton within the framework of a nonrelativistic constituent quark model. The Compton tensor is divided into two separately gauge-invariant contributions. The first consists of the groundstate propagation in the direct and crossed channels together with an appropriately chosen term to satisfy gauge invar

P. Zhuang, M. Huang, Z. Yang

The hadronization cross section in a quark plasma at finite temperature and density is calculated in the framework of Nambu--Jona-lasinio model with explicit chiral symmetry breaking. In apposition to the familiar temperature effect, the quark plasma at high density begins to hadronize suddenly. It leads to a sudden and strong increase of final state pions i

Pengfei Zhuang, Zhenwei Yang

The energy and baryon densities in heavy ion collisions are estimated by analytically solving a 1+1 dimensional hydrodynamical model with source terms. Particularly, a competition between the energy and baryon sources and the expansion of the system is discussed in detail.

P. Zhuang, Z. Yang

Sigma decay and its relation with chiral phase transition are discussed at finite temperature and density in the framework of the Nambu-Jona-Lasinio model. The decay rate for the process sigma -> 2 pions to first order in a 1/N_c expansion is calculated as a function of temperature T and baryon density n_b. In particular, only when the chiral phase transitio

V. Korepin, P. Zinn-Justin

In this note, we consider the six-vertex model with domain wall boundary conditions, defined on a $M\times M$ lattice, in the inhomogeneous case where the partition function depends on 2M inhomogeneities $λ_j$ and $μ_k$. For a particular choice of the set of $λ_j$ we find a new determinant representation for the partition function, which allows evaluation of

C. Quesne

$C_λ$-extended oscillator algebras, generalizing the Calogero-Vasiliev algebra, where $C_λ$ is the cyclic group of order $λ$, have recently proved very useful in the context of supersymmetric quantum mechanics and some of its variants. Here we determine the spectrum generating algebra of the $C_λ$-extended oscillator. We then construct its coherent states, s

N. S. Witte, P. J. Forrester, Christopher M. Cosgrove

The probability that an interval $I$ is free of eigenvalues in a matrix ensemble with unitary symmetry is given by a Fredholm determinant. When the weight function in the matrix ensemble is a classical weight function, and the interval $I$ includes an endpoint of the support, Tracy and Widom have given a formalism which gives coupled differential equations f

N. S. Witte, P. J. Forrester, Christopher M. Cosgrove

The probabilities for gaps in the eigenvalue spectrum of the finite dimension $ N \times N $ random matrix Hermite and Jacobi unitary ensembles on some single and disconnected double intervals are found. These are cases where a reflection symmetry exists and the probability factors into two other related probabilities, defined on single intervals. Our invest

Manfred Requardt

We develop a graph-Hilbert-space framework, inspired by non-commutative geometry, on (infinite) graphs and use it to study spectral properies of \tit{graph-Laplacians} and so-called \tit{graph-Dirac-operators}. Putting the various pieces together we define a {\it spectral triplet} sharing most (if not all, depending on the particular graph model) of the prop