May 1999 arXiv papers — page 11

N. Marchal, R. Peschanski

Using the asymptotic conformal invariance of perturbative QCD we derive the expression of the coupling of external states to all conformal spin-p components of the forward elastic amplitude. Using the wave-function formalism for structure functions at small x, we derive the perturbative coupling of the virtual photon for p= 1, which is maximal for linear tra

B. W. Harris, E. Laenen, S. Moch, J. Smith

We discuss two topics in the production of heavy quarks in deep-inelastic scattering: the next-to-leading order Monte-Carlo HVQDIS and the next-to-leading logarithmic resummation of soft gluon effects, including estimates of next-to-next-to-leading order corrections therefrom.

Daniel Arndt, Chueng-Ryong Ji

We present a relativistic constituent quark model to analyze the mass spectrum and hadronic properties of radially excited u and d quark sector mesons. Using a simple Gaussian function as a trial wave function for the variational principle of a QCD motivated Hamiltonian, we obtain the mass spectrum consistent with the experimental data. To do the same for se

Robin G. Stuart

Over 40 years after the calculation of the 1-loop QED corrections to the muon lifetime, new theoretical developments have made it possible to obtain an analytic expression for the complete 2-loop QED contributions in the Fermi theory. The exact result for the effects of virtual and real photons, virtual electrons, muons and hadrons as well as e+e- pair creat

O. Kaczmarek, with J. Engels, F. Karsch, E. Laermann

We discuss the quenched limit of lattice QCD at non-zero baryon number density. We find evidence for a mixed phase that becomes broader with increasing baryon number. Although the action is explicitly Z(3) symmetric the Polyakov loop expectation value becomes non-zero already in the low temperature phase. It indicates that the heavy quark potential stays fin

Simon Hands, Susan Morrison

We review efforts to study, using the methods of lattice field theory, the phenomenon of diquark condensation via BCS pairing at a Fermi surface, which has been proposed as a mechanism for color superconductivity in dense quark matter. The particular models studied are the Gross-Neveu model and SU(2) lattice gauge theory; in both cases evidence for superflui

M. Doucet, J. Panman, P. Zucchelli

We present a study for a design of a long baseline nu_mu to nu_tau appearance experiment to probe the high sin^2(2theta) and low Delta m^2 region relevant to explain the atmospheric neutrino anomaly. The experiment relies on a good identification of quasi-elastic interactions, which is a clean topology that has an important contribution in the lowest Delta m

Masaru Shibata, Misao Sasaki

We study formation of black holes in the Friedmann universe. We present a formulation of the Einstein equations under the constant mean curvature time-slicing condition. Our formalism not only gives us the analytic solution of the perturbation equations for non-linear density and metric fluctuations on superhorizon scales, but also allows us to carry out a n

J. -F. Pascual-Sánchez

In this essay, I present an alternative explanation for the cosmic acceleration which appears as a consequence of recent high redshift Supernova data. In the usual interpretation, this cosmic acceleration is explained by the presence of a positive cosmological constant or vacuum energy, in the background of Friedmann models. Instead, I will consider a Local

M. Gasperini

String theory can (in principle) describe gravity at all curvature scales, and can be applied to cosmology to look back in time beyond the Planck epoch. The duality symmetries of string theory suggest a cosmological picture in which the imprint of a primordial, pre-big bang phase could still be accessible to present observations. The predictive power of such

Mark J Hadley

The non-classical features of quantum mechanics are reproduced using models constructed with a classical theory - general relativity. The inability to define complete initial data consistently and independently of future measurements, non-locality, and the non-Boolean logical structure are reproduced by these examples. The key feature of the models is the ro

Brendan S. Guilfoyle

The static electrogravitational equations are studied and it is shown that an aligned type D metric which has a Weyl-type relationship between the gravitational and electric potential has shearfree geodesic lines of force. All such fields are then found and turn out to be the fields of a charged sphere, charged infinite rod and charged infinite plate. A furt

J. Carot, J. M. M. Senovilla, R. Vera

The standard definition of cylindrical symmetry in General Relativity is reviewed. Taking the view that axial symmetry is an essential pre-requisite for cylindrical symmetry, it is argued that the requirement of orthogonal transitivity of the isometry group should be dropped, this leading to a new, more general definition of cylindrical symmetry. Stationarit

X. Y. Lee, H. W. Jiang, W. J. Schaff

We present a phase diagram for a two-dimensional electron system with two populated subbands. Using a gated GaAs/AlGaAs single quantum well, we have mapped out the phases of various quantum Hall states in the density-magnetic filed plane. The experimental phase diagram shows a very different topology from the conventional Landau fan diagram. We find regions

E. S. Lee, C. Geckeler, J. Heurich, A. Gupta

We combine the ideas of dressed Bose-Einstein condensates, where an intracavity optical field allows one to design coupled, multicomponent condensates, and of dark states of quantum systems, to generate a full quantum entanglement between two matter waves and two optical waves. While the matter waves are macroscopically populated, the two optical modes share

Arkadiusz Wojs, John J. Quinn

The mean field (MF) composite Fermion (CF) picture successfully predicts low lying states of fractional quantum Hall systems. This success cannot be attributed to a cancellation between Coulomb and Chern-Simons interactions beyond the mean field and solely depends on the short range (SR) of the Coulomb pseudopotential in the lowest Landau level (LL). The cla

J. B. Sokoloff, M. S. Tomassone, A. Widom

A sudden drop in mechanical friction, between an adsorbed nitrogen monolayer and a lead substrate, occurs when the lead passes through the superconducting transition temperature. We attribute this effect to a sudden drop at the superconducting transition temperature of the substrate Ohmic heating. The Ohmic heating is due to the electronic screening current

C. Grimaldi

When non-magnetic impurities are introduced in a d-wave superconductor, both thermodynamic and spectral properties are strongly affected if the impurity potential is close to the strong resonance limit. In addition to the scalar impurity potential, the charge carriers are also spin-orbit coupled to the impurities. Here it is shown that (i) close to the unita

Claudio Brangian, Oreste Pilla, Gabriele Viliani

Relaxation phenomena in glasses can be related to jump processes between different minima of the potential energy in the configuration space. These transitions play a key role in the low temperature regime, giving rise to tunneling systems responsible for the anomalous specific heat and thermal conductivity in disordered solids with respect to crystals. By u

Frithjof B. Anders

The magnetic properties of the two-channel periodic Anderson model for uranium ions, comprised of a quadrupolar and a magnetic doublet are investigated through the crossover from the mixed-valent to the stable moment regime using dynamical mean field theory. In the mixed-valent regime ferromagnetism is found for low carrier concentration on a hyper-cubic lat

Luis E. Oxman, Eduardo R. Mucciolo, Ilya V. Krive

We show that the conductance of a one-dimensional, finite charge-density-wave (CDW) system of the incommensurate type is not renormalized at low temperatures and depends solely on the leads. Within our formalism, we argue that a similar behavior (perfect conductance) should occur for a wide class of one-dimensional strongly correlated finite systems where in

Alban L. Fauchere

Superconductivity, discovered by Kamerlingh Onnes in 1911, continues to be a fascinating subject of condensed matter physics today. Much interest has been devoted to the study of the superconductivity induced in a metal which by itself is not superconducting but is in electrical contact with a superconductor. As the carriers of superconductivity, the Cooper

A. Mourachkine

In this Comment, we explain the reason for the discrepancy between two sets of tunneling data obtained on Ni- and Zn-doped Bi2212 single crystals (presented in H. Hancotte et al., Phys. Rev. B 55, R3410 (1997) and A. Mourachkine, to be published in J. of Superconductivity, cond-mat/9902355).

Cesar R. de Oliveira, Giancarlo Q. Pellegrino

We propose an effective exponent ruling the algebraic decay of the average quantum return probability for discrete Schrodinger operators. We compute it for some non-periodic substitution potentials with different degrees of randomness, and do not find a complete qualitative agreement with the spectral type of the substitution sequences themselves, i.e., more

Alexandra Roder, Joan Adler, Wolfhard Janke

We derive high-temperature series expansions for the free energy and susceptibility of the two-dimensional random-bond Ising model with a symmetric bimodal distribution of two positive coupling strengths J_1 and J_2 and study the influence of the quenched, random bond-disorder on the critical behavior of the model. By analysing the series expansions over a w

P. Degiovanni, S. Peysson

Using its Conformal Field Theory description, the Luttinger liquid is coupled to the quantum electromagnetic field. We compute the decoherence properties of a superposition of two states obtained by creating the same elementary excitation at different places in the system.

M. Bauer, C. Godreche, J. M. Luck

The statistics of persistent events, recently introduced in the context of phase ordering dynamics, is investigated in the case of the 1D lattice random walk in discrete time. We determine the survival probability of the random walker in the presence of an obstacle moving ballistically with velocity v, i.e., the probability that the walker remains up to time

Ramin Golestanian

Using a generalization of the Poisson-Boltzmann equation, dynamics of counterion condensation is studied. For a single charged plate in the presence of counterions, it is shown that the approach to equilibrium is diffusive. In the far from equilibrium case of a moving charged plate, a dynamical counterion condensation transition occurs at a critical velocity

H. Yasuhara, S. Yoshinaga, M. Higuchi

The experimentally predicted narrowing in the bandwidth of sodium is interpreted in terms of the non-local self-energy effect on quasi-particle energies of the electron liquid. The calculated self-energy correction is a monotonically increasing function of the wavenumber variable. The usual analysis of photo-emission experiments assumes the final state energ

K. V. Samokhin

The persistent current in a clean mesoscopic ring with ballistic electron motion is calculated. The particle dynamics inside a ring is assumed to be chaotic due to scattering at the surface irregularities of atomic size. This allows one to use the so-called ``ballistic'' supersymmetric σmodel for calculation of the two-level correlation function in t

Walter Kob, Jean-Louis Barrat

By means of molecular dynamics computer simulations we investigate the out of equilibrium relaxation dynamics of a simple glass former, a binary Lennard-Jones system, after a quench to low temperatures. We study both one time quantities and two-times correlation functions. Two-times correlation functions show a strong time and waiting time $t_w$ dependence.

M. Ulmke, R. T. Scalettar

We describe a new algorithm for the numerical simulation of quantum spin and boson systems. The method is based on the Trotter decomposition in imaginary time and a decoupling by auxiliary Ising spins. It can be applied, in principle, to arbitrary (random) spin systems, however in general it suffers from the ``minus-sign problem''. This problem is ab

P. Husser, H. U. Suter, E. P. Stoll, P. F. Meier

We present the results of first-principles cluster calculations of the electronic structure of La_2CuO_4. Several clusters containing up to nine copper atoms embedded in a background potential were investigated. Spin-polarized calculations were performed both at the Hartree-Fock level and with density functional methods with generalized gradient corrections

T. Strasser, C. Solterbeck, F. Starrost, W. Schattke

A detailed investigation by one-step photoemission calculations of the GaN(0001)-(1x1) surface in comparison with recent experiments is presented in order to clarify its structural properties and electronic structure. The discussion of normal and off-normal spectra reveals through the identified surface states clear fingerprints for the applicability of a su

V. J. Goldman

We would like to point out that: (i) according to the edge-bulk transport models for the quantum Hall regime, the direction of low bulk conductance is actually perpendicular to that expected naively; and (ii) the values of experimental "high resistance" peaks correspond to value of bulk conductance $\approx 1 e^{2}/h$.

Fei Zhou

In this Letter, we consider the adiabatic charge transport through a normal mesoscopic sample sandwiched by superconductors without modulation of local chemical potentials. The deformation of coherent quasiparticles in the normal metal in the presence of periodically changing phases in the superconductors leads to a charge transport. Both the magnitude and t

B. Gutkin, U. Smilansky, E. Gutkin

We establish sufficient conditions for the hyperbolicity of the billiard dynamics on surfaces of constant curvature. This extends known results for planar billiards. Using these conditions, we construct large classes of billiard tables with positive Lyapunov exponents on the sphere and on the hyperbolic plane.

D. Boose, J. Main

The quantitative contributions of a mixed phase-space to the mean characterizing the distribution of diagonal transition matrix elements and to the variance characterizing the distributions of non-diagonal transition matrix elements are studied. It is shown that the mean can be expressed as the sum of suitably weighted classical averages along an ergodic tra

N. V. Antonov, M. Hnatič, M. Yu. Nalimov

Statistical model of strongly anisotropic fully developed turbulence of the weakly compressible fluid is considered by means of the field theoretic renormalization group. The corrections due to compressibility to the infrared form of the kinetic energy spectrum have been calculated in the leading order in Mach number expansion. Furthermore, in this approxima

Michael Chertkov, Alain Pumir, Boris I. Shraiman

A new phenomenological model of turbulent fluctuations is constructed by considering the Lagrangian dynamics of 4 points (the tetrad). The closure of the equations of motion is achieved by postulating an anisotropic, i.e. tetrad shape dependent, relation of the local pressure and the velocity gradient defined on the tetrad. The non-local contribution to the

M. Patra, H. Schomerus, C. W. J. Beenakker

A random-matrix theory is presented for the linewidth of a laser cavity in which the radiation is scattered chaotically. The linewidth is enhanced above the Schawlow-Townes value by the Petermann factor K, due to the non-orthogonality of the cavity modes. The factor K is expressed in terms of a non-Hermitian random matrix and its distribution is calculated e

S. R. Majewski, M. H. Siegel, Richard J. Patterson, R. T. Rood

We present BV photometry of the Sculptor dwarf galaxy to V=22. These data give evidence for a bimodality in Sculptor's metallicity distribution based on a discontinuity in the luminosities of horizontal branch (HB) stars and by the presence of two distinct red giant branch (RGB) bumps. A consistent picture of the evolved stars in Sculptor is given by the

Taft E. Armandroff, George H. Jacoby, James E. Davies

We present B-, V-, and I-band images, as well as an H alpha image, of And VI. This is the second newly identified dwarf spheroidal (dSph) companion to M31 found using a digital filtering technique applied to the second Palomar Sky Survey for which 1550 square degrees now have been surveyed. And VI was confirmed to be a nearby dSph galaxy when it resolved int

P. Kaaret, S. Piraino, P. F. Bloser, E. C. Ford

The behavior of quasi-periodic oscillations (QPOs) at frequencies near 1 kHz in the x-ray emission from the neutron star x-ray binary 4U1820-30 has been interpreted as evidence for the existence of the marginally stable orbit, a key prediction of strong-field general relativity. The signature of the marginally stable orbit is a saturation in QPO frequency, a

Lionel Siess, Mario Livio

This paper extends our previous study of planet/brown dwarf accretion by giant stars to solar mass stars located on the red giant branch. The model assumes that the planet is dissipated at the bottom of the convective envelope of the giant star. The giant's evolution is then followed in detail. We analyze the effects of different accretion rates and diff

D. E. Welty, L. M. Hobbs, J. T. Lauroesch, D. C. Morton

Spectra obtained with the Hubble Space Telescope GHRS are combined with high-resolution optical spectra and UV spectra from Copernicus to study the abundances and physical conditions in the diffuse interstellar clouds seen along the line of sight to the star 23 Ori. Strong low-velocity (SLV) absorption, due to cool, moderately dense neutral gas and represent

Vincent M. Woolf, David L. Lambert

We report the detection of three mercury-manganese stars in the Orion OB1 association. HD 37886 and BD-0 984 are in the approximately 1.7 million year old Orion OB1b. HD 37492 is in the approximately 4.6 million year old Orion OB1c. Orion OB1b is now the youngest cluster with known HgMn star members. This places an observational upper limit on the time scale

D. Barrado y Navascues, J. R. Stauffer, C. Briceño

We present a deep survey of the young southern cluster IC2391. We have covered 2 sq. degrees in the R,I filter. We have selected several dozens VLM stars and BD candidates based on the position of these objects in the Color-Magnitude Diagram.

D. Barrado y Navascues, J. R. Stauffer, J. Bouvier

We review our the status of the photometric searches of brown dwarfs and vely low mass stars in several young open clusters and present some results on the spectroscopic follow-up, including new cluster ages based on the position of the lithium depletion boundary.

D. Barrado y Navascues, J. R. Stauffer, J. Bouvier, E. L. Martin

We present very deep RIc photometry of the M35 open cluster. We have covered 30' \times 30', equivalent to about a fourth of the total area of the cluster. The data range from I_c=17.5 to 23.5 magnitudes, and the color interval is $0.5 \le (R-I)_c \le 2.5$. Roughly, these values correspond from $0.6 M_\odot$ to $0.1 M_\odot$ in the cases of members o

Luiz da Costa

The imaging data assembled by the recently completed ESO Imaging Survey (EIS) are reviewed and their scientific value briefly assessed. Among the various applications, the imaging data has been used to build a large sample of candidate distant clusters of galaxies in the Southern Hemisphere to be used for follow-up observations with the VLT as well as other

T. Foglizzo, M. Ruffert

The adiabatic shock produced by a compact object moving supersonically relative to a gas with uniform entropy and no vorticity is a source of entropy gradients and vorticity. We investigate these analytically. The non-axisymmetric Rayleigh-Taylor and axisymmetric Kelvin-Helmholtz linear instabilities are potential sources of destabilization of the subsonic a

Sergei A. Trushkin

We present compiled radio continuum spectra for 200 Galactic supernova remnants (SNRs) from 220 known and included in Green's (1998) catalog. These spectra include most of the measurements available in literature, as well as multi-frequency measurements of nearly 120 SNRs with the RATAN-600 radio telescope in 1, 2 and 4 Galactic quadrants and from the Ga

A. Wandel, B. M. Peterson, M. A. Malkan

The masses and emission-line region sizes of Active Galactic Nuclei (AGNs) can be measured by ``reverberation-mapping'' (measuring the lag of the emission-line luminosity after changes in the continuum). We use tis technique to calibrate similar size and mass estimates made by photoionization models of the AGN line-emitting regions. We compile a samp

Richard Lieu, Jonathan P. D. Mittaz, Massimiliano Bonamente, Florence Durret

Several authors (S. Bowyer, T. Berghoeffer, and E. Korpela, hereinafter abbreviated as BBK) recently announced that the luminous extended EUV radiation from the clusters Abell 1795 and Abell 2199, which represents the large scale presence of a new and very soft emission component, is an illusion in the EUVE Deep Survey (DS) detector image. Specifically BBK f

Wendy L. Freedman

Rapid progress has been made recently toward the measurement of cosmological parameters. Still, there are areas remaining where future progress will be relatively slow and difficult, and where further attention is needed. In this review, the status of measurements of the matter density, the vacuum energy density or cosmological constant, the Hubble constant,

Chris Loken, Adrian L. Melott, Christopher J. Miller

With the availability of large-scale redshift survey data, it is now becoming possible to explore correlations between large-scale structure and the properties and morphologies of galaxy clusters. We investigate the spatial distributions of a 98% complete, volume-limited sample of nearby (z<0.1) Abell clusters with well-determined redshifts and find that coo

E. Aubourg, N. Palanque-Delabrouille, P. Salati, M. Spiro

The observed microlensing events towards the LMC do not have yet a coherent explanation. If they are due to Galactic Halo objects, the nature of these objects is puzzling --- half the halo in dark 0.5 Msol objects. On the other hand, traditional models of the LMC predict a self-lensing optical depth about an order of magnitude too low, although characteristi

Damian H. Zanette

A simple mathematical model is proposed to study the effect of the average trend of a population on the opinion of each individual, when a group decision has to be made by voting. It is shown that if such effect is strong enough a transition to coherent behavior occurs, in which the whole population converges to a single opinion. This transition has the char

A. Skibinsky, S. V. Buldyrev, A. Scala, S. Havlin

We investigate the formation of a two-dimensional quasicrystal in a monodisperse system, using molecular dynamics simulations of hard sphere particles interacting via a two-dimensional square-well potential. We find that more than one stable crystalline phase can form for certain values of the square-well parameters. Quenching the liquid phase at a very low

M. Baker, R. Steinke

We obtain an effective string theory of the Abrikosov-Nielsen-Olesen vortices of the Abelian Higgs model. The theory has an anomaly free effective string action which, when the extrinsic curvature is set equal to zero, yields the Nambu-Goto action. This generalizes previous work in which a string representation was obtained in the London limit, where the mag

S. Prem Kumar, Daniel Boyanovsky, Hector J. de Vega, Richard Holman

The anomalous pseudoscalar-photon vertex is studied in real time in and out of equilibrium in a constituent quark model. The goal is to understand the in-medium modifications of this vertex, exploring the possibility of enhanced isospin breaking by electromagnetic effects as well as the formation of neutral pion condensates in a rapid chiral phase transition

Ph. Droz-Vincent

The Klein-Gordon system describing three scalar particles without interaction is cast into a new form, by transformation of the momenta. Two redundant degrees of freedom are eliminated; we are left with a covariant equation for a reduced wave function with three-dimensional arguments. This new formulation of the mass-shell constraints is equivalent to the or

K. Ogure, J. Sato

We investigate a phase transition of the O(N) invariant scalar model using the auxiliary mass method. We determine the critical exponent $β$ by calculating an effective potential below the critical temperature. This work follows that of a previous paper.

M. E. S. Borelli, H. Kleinert, Adriaan M. J. Schakel

The effect of quantum fluctuations on a nearly flat, nonrelativistic two-dimensional membrane with extrinsic curvature stiffness and tension is investigated. The renormalization group analysis is carried out in first-order perturbative theory. In contrast to thermal fluctuations, which soften the membrane at large scales and turn it into a crumpled surface,

G. W. Semenoff, I. A. Shovkovy, L. C. R. Wijewardhana

The hypothesis that the magnetic catalysis of chiral symmetry breaking is due to interactions of massless fermions in their lowest Landau level is examined in the context of chirally symmetric models with short ranged interactions. It is argued that, when the magnetic field is sufficiently large, even an infinitesimal attractive interaction in the appropriat

D. H. Coule, Jerome Martin

Quantum creation of Universes with compact spacelike sections that have curvature $k$ either closed, flat or open, i.e. $k=\pm1,0$ are studied. In the flat and open cases, the superpotential of the Wheeler De Witt equation is significantly modified, and as a result the qualitative behaviour of a typical wavefunction differs from the traditional closed case.

Indrajit Mitra

Assuming high temperature and taking subleading temperature dependence into account, gauge dependence of one-loop electron dispersion relation is investigated in massless QED at zero chemical potential. The analysis is carried out using a general linear covariant gauge. The equation governing the gauge dependence of the dispersion relation is obtained and us

Sanjib Sabhapandit, Prabodh Shukla, Deepak Dhar

We consider the zero-temperature single-spin-flip dynamics of the random-field Ising model on a Bethe lattice in the presence of an external field h. We derive the exact self-consistent equations to determine the distribution Prob(s) of avalanche sizes s, as the external field increases from large negative to positive values. We solve these equations explici

M. Caselle, F. Gliozzi

We discuss a new cluster representation for the internal energy and the specific heat of the d-dimensional Ising model, obtained by studying the percolation mapping of an Ising model with an arbitrary set of antiferromagnetic links. Such a representation relates the thermal operators to the topological properties of the Fortuin-Kasteleyn clusters of Ising pe

V. Capek, J. Bok

A previously published model of the isothermal Maxwell demon as one of models of open quantum systems endowed with faculty of selforganization is reconstructed here. It describes an open quantum system interacting with a single thermodynamic bath but otherwise not aided from outside. Its activity is given by the standard linear Liouville equation for the sys

Chris Van Den Broeck, Kor Van Hoof

We perform the gauge-fixing of the theory of a chiral two-form boson in six dimensions starting from the action given by Pasti, Sorokin and Tonin. We use the Batalin-Vilkovisky formalism, introducing antifields and writing down an extended action satisfying the classical master equation. Then we gauge-fix the three local symmetries of the extended action in

K. Kleidis, N. K. Spyrou

Stimulated by the methods applied for the observational determination of masses in the central regions of the AGNs, we examine the conditions under which, in the interior of a gravitating perfect fluid source, the geodesic motions and the general relativistic hydrodynamic flows are dynamically equivalent to each other. Dynamical equivalence rests on the func

N. Giglietto

Using over 40 million muons collected since 1989 by the MACRO detector we have searched for a depletion of muons coming from the direction of the Moon due to primary cosmic rays striking the Moon. We observe this Moon shadow in the expected position with a statistical significance of more than 5 standard deviations. We have analyzed the same data for an anal

V. V. Kiselev, A. K. Likhoded, A. I. Onishchenko

The semileptonic B_c-meson decays into the heavy quarkonia J/ψ(η_c) and a pair of leptons are investigated in the framework of three-point sum rules of QCD and NRQCD. Calculations of analytical expressions for the spectral densities of QCD and NRQCD correlators with account for the Coulomb-like α_s/v terms are presented. The generalized relations due to the

J. Takeya, I. Tsukada, Yoichi Ando, T. Masuda

The thermal conductivity $κ$ is measured in a series of Cu_1-xMg_xGeO_3 single crystals in magnetic fields up to 16 T. It has turned out that heat transport by spin excitations is coherent for lightly doped samples, in which the spin-Peierls (SP) transition exists, at temperatures well above the SP transition temperature T_SP. Depression of this spin heat tr

P. V. Shevchenko, A. W. Sandvik, O. P. Sushkov

The double-layer Heisenberg antiferromagnet with intra- and inter-layer couplings $J$ and $J_\perp$ exhibits a zero temperature quantum phase transition between a quantum disordered dimer phase for $g>g_c$ and a Neel phase with long range antiferromagnetic order for $g<g_c$, where $g=J_\perp/J$ and $g_c \approx 2.5$. We consider the behavior of the system at

Henry P. Stapp

The need for a self-observing quantum system to pose questions leads to a tripartite quantum process involving a Schroedinger process that is local deterministic, a Heisenberg process that poses the question, and a Dirac process that picks the answer. In the classical limit where Planck&#39;s constant is set to zero these three processes reduce to one single

Henry P. Stapp

Aspects of a quantum mechanical theory of a world containing efficacious mental aspects that are closely tied to brains, but that are not identical to brains.

E. De Angelis, F. De Martini, P. Mataloni

We report the results of the first investigation on the superradiant temporal and spatial quantum dynamics of two dipoles excited in a planar symmetrical microcavity by a controlled femtosecond two-pulse excitation. A superradiant enhancement of the time decay of the dipole excitation for a decreasing inter-dipole transverse distance R has been found. Furthe

G Ball, K Vant, N Christensen

We present a detailed numerical study of a chaotic classical system and its quantum counterpart. The system is a special case of a kicked rotor and for certain parameter values possesses cantori dividing chaotic regions of the classical phase space. We investigate the diffusion of particles through a cantorus; classical diffusion is observed but quantum diff

Waldemar Puszkarz

We show an example of benign non-separability in an apparently separable system consisting of $n$ free non-correlated quantum particles, solitonic solutions to the nonlinear phase modification of the Schrödinger equation proposed recently. The non-separability manifests itself in the wave function of a single particle being influenced by the very presence of

Waldemar Puszkarz

We present some physically interesting, in general non-stationary, one-dimensional solutions to the nonlinear phase modification of the Schrödinger equation proposed recently. The solutions include a coherent state, a phase-modified Gaussian wave packet in the potential of harmonic oscillator whose strength varies in time, a free Gaussian soliton, and a simi

Waldemar Puszkarz

We observe that in nonlinear quantum mechanics, unlike in the linear theory, there exists, in general, a difference between the energy functional defined within the Lagrangian formulation as an appropriate conserved component of the canonical energy-momentum tensor and the energy functional defined as the expectation value of the corresponding nonlinear Hami

Waldemar Puszkarz

A nonlinear modification of the Schrödinger equation is proposed in which the Lagrangian density for the Schrödinger equation is extended by terms polynomial in $Δ^{m}\ln (Ψ^{*}/Ψ)$ multiplied by $Ψ^{*}Ψ$. This introduces a homogeneous nonlinearity in a Galilean invariant manner through the phase $S$ rather than the amplitude $R$ of the wave function $Ψ=R\ex

Waldemar Puszkarz

We propose a nonlinear modification of the Schrödinger equation that possesses the main properties of this equation such as the Galilean invariance, the weak separability of composite systems, and the homogeneity in the wave function. The modification is derived from the relativistic relation between the energy and momentum of free particle and, as such, it

Waldemar Puszkarz

We modify the Schrödinger equation in a way that preserves its main properties but makes use of higher order derivative terms. Although the modification represents an analogy to the Doebner-Goldin modification, it can differ from it quite distinctively. A particular model of this modification including derivatives up to the fourth order is examined in greate

Valery P. Dmitriyev

A quasielastic model of gravitation is developed. Gravitational field is modeled by the flow of the transient point dilatation, which is supposed to be continually emitted by a discontinuity of the turbulent fluid. Gravitational attraction arises from the contact interaction of the dilatation centers. Gravitational wave is viewed microscopically as the axisy

W. Li, X. Cai

Quark rotation asymmetry is proposed in calculating baryon magnetic moments. After taking into account interactions enforced on constituent quarks, assumed to be linear and Coulomb potentials, respectively, and the quark rotation asymmetry, we fit the theoretical values, based on two more hypotheses and several other reasonable assumptions, of baryon magneti

M. C. Birse, J. A. McGovern, S. Pepin, N. R. Walet

We study the nucleon solution of the relativistic Faddeev equation as a function of density in the framework of a generalized Nambu-Jona-Lasinio model. We truncate the interacting two-body channels to the scalar diquark channel, the coupling constant of which is treated as a parameter. A 3-momentum cut-off is used to regularize the model. The Faddeev equatio

K. Turner, the STAR Collaboration

The STAR experiment at RHIC is a TPC-based, general purpose detector designed to obtain charged particle spectra, with an emphasis on hadrons over a large phase space. An electromagnetic calorimeter provides measurement of electrons, photons, pi-zeros and jets. Data-taking with Au+Au collisions at sqrt(s)= 200 GeV/c**2 begins in Fall 1999. The STAR experimen

Yu. A. Neretin

We give a simple explanaition of classical boson-fermion correspondence.

Fabio Giannoni, Antonio Masiello, Paolo Piccione

In this paper we develop a Morse Theory for timelike geodesics parameterized by a constant multiple of proper time. The results are obtained using an extension to the timelike case of the relativistic Fermat Principle, and techniques from Global Analysis on infinite dimensional manifolds. In the second part of the paper we discuss a limit process that allows

K. R. Goodearl, J. T. Stafford

The analogue of Goldie&#39;s Theorem for prime rings is proved for rings graded by abelian groups, eliminating unnecessary additional hypotheses used in earlier versions.

Eui Chul Kim, Thomas Friedrich

We construct exact solutions of the Einstein-Dirac equation, which couples the gravitational field with an eigenspinor of the Dirac operator via the energy-momentum tensor. For this purpose we introduce a new field equation generalizing the notion of Killing spinors. The solutions of this spinorial field equation are called weak Killing spinors (WK-spinors).

Bernadette Krawczyk, Roland Speicher

We derive a formula for expressing free cumulants whose entries are products of random variables in terms of the lattice structure of non-crossing partitions. We show the usefulness of that result by giving direct and conceptually simple proofs for a lot of results about $R$-diagonal elements. Our investigations do not assume the trace property for the consi

S. De Leo, G. Ducati

Due to the non-commutative nature of quaternions we introduce the concept of left and right action for quaternionic numbers. This gives the opportunity to manipulate appropriately the $H$-field. The standard problems arising in the definitions of transpose, determinant and trace for quaternionic matrices are overcome. We investigate the possibility to formul

S. De Leo, WA Rodrigues, J. Vaz

Complex geometry represents a fundamental ingredient in the formulation of the Dirac equation by the Clifford algebra. The choice of appropriate complex geometries is strictly related to the geometric interpretation of the complex imaginary unit $i=\sqrt{-1}$. We discuss {\em two} possibilities which appear in the multivector algebra approach: the $σ_{123}$

S. De Leo, K. Abdel-Khalek

In order to obtain a consistent formulation of octonionic quantum mechanics (OQM), we introduce left-right barred operators. Such operators enable us to find the translation rules between octonionic numbers and $8\times 8$ real matrices (a translation is also given for $4\times 4$ complex matrices). The use of a complex geometry allows us to overcome the her

Mary K. Gaillard, Brent Nelson, Yi-Yen Wu

We calculate gaugino masses in string-derived models with hidden-sector gaugino condensation. The linear multiplet formulation for the dilaton superfield is used to implement perturbative modular invariance. The contribution arising from quantum effects in the observable sector includes the term recently found in generic supergravity models. A much larger co