April 1997 arXiv papers — page 4

Ph. Brax, J. Mourad

We consider open supermembranes in an eleven dimensional background. We show that, in a flat space-time, the world-volume action is kappa-symmetric and has global space-time supersymmetry if space-time has even dimensional topological defects where the membrane can end. An example of such topological defects is provided by the space-time with boundaries cons

W. Beenakker

A survey is given of the various aspects of W-boson physics at the next generation of linear colliders. In particular, it is indicated how the W boson can help us improve our understanding of the mechanism of mass generation and the structure of the non-abelian gauge-boson interactions. Also the topics of radiative corrections and gauge invariance are briefl

F. Klingl, N. Kaiser, W. Weise

Based on an effective Lagrangian which combines chiral SU(3) dynamics with vector meson dominance, we have developed a model for the forward vector meson-nucleon scattering amplitudes. We use this as an input to calculate the low energy part of the current-current correlation function in nuclear matter. Its spectrum enters directly in the ``left hand side&#3

T. Waas, R. Brockmann, W. Weise

We show that the s-wave pion-nuclear potential which reproduces the deeply bound pionic states in Pb, recently discovered at GSI, is remarkably close to the one constructed directly from low energy theorems based on chiral symmetry. Converting this information into an effective pion mass we find $m_π^\star/m_π\simeq 1.13$ in the center of the Pb nucleus, and

S. Groote, J. G. Körner, A. A. Pivovarov

By exploiting the analyticity properties of the two-point current-current correlator we obtain numerical predictions for the $e^+e^-$ moments in terms of the $τ$ decay rate. We perform a partial resummation of the pertinent perturbative series expansion by solving the renormalization group equation for Adler's function. Our predictions are renormalizatio

V. P. Gusynin, I. A. Shovkovy

The catalysis of chiral symmetry breaking in the massless weakly coupled QED in a magnetic field at finite temperature is studied. The temperature of the symmetry restoration is estimated analytically as $T_c\simeq m_{dyn}$, where $m_{dyn}$ is the dynamical mass of a fermion at zero temperature.

Uma Mahanta

A two higgs doublet model with tree level natural flavor conservation can lead to P and T odd nucleon-nucleon (NN) interaction through tree level Feynman diagrams. In this article we estimate the magnitudes of the parameters that characterize the strength of the S-PS type of NN interaction. Stringent constraints on the parameters can be derived from the meas

K. K. Sharma, R. C. Verma

We study two-body weak decays of charmed baryons Λ_c and Ξ_c into an octet or decuplet baryon and a pseudoscalar meson employing the SU(3) flavor symmetry. Using certain measured Cabibbo-favored modes, we fix the reduced amplitudes and predict the branching ratios of various decays of charmed baryons in the Cabibbo-enhanced, -suppressed and -doubly suppresse

Dave Sutter

The supersymmetric $SU(3)\times SU(2)\times U(1)$ theory with minimal particle content and general soft supersymmetry breaking terms has 110 physical parameters in its flavor sector: 30 masses, 39 mixing angles, and 41 phases. These parameters contain many new measurable sources of flavor violations unless either the sparticle mass splittings and mixing angl

W. Bietenholz, R. Brower, S. Chandrasekharan, U. -J. Wiese

Lattice actions and topological charges that are classically and quantum mechanically perfect (i.e. free of lattice artifacts) are constructed analytically for the quantum rotor. It is demonstrated that the Manton action is classically perfect while the Villain action is quantum perfect. The geometric construction for the topological charge is only perfect a

P. Kaste, H. J. Rothe

We compute the electric screening mass in lattice QCD with Wilson fermions at finite temperature and chemical potential to one-loop order, and show that lattice artefacts arising from a finite lattice spacing result in an enhancement of the screening mass as compared to the continuum. We discuss the magnitude of this enhancement as a function of the temperat

The SLD Collaboration, K. Abe, K. Abe, T. Akagi

We present direct measurements of the $Z^0$-lepton coupling asymmetry parameters, $A_e$, $A_μ$, and $A_τ$, based on a data sample of 12,063 leptonic $Z^0$ decays collected by the SLD detector. The $Z$ bosons are produced in collisions of beams of polarized $e^-$ with unpolarized $e^+$ at the SLAC Linear Collider. The couplings are extracted from the measurem

G. Giampieri

The response of an interferometer changing its orientation with respect to a fixed reference frame is given in terms of the beam-pattern factors and the polarization-averaged antenna power pattern.

Naresh Dadhich

General relativity is a non-linear theory with the distinguishing feature that gravitational field energy also acts as gravitational charge density. In the well-known Schwarzschild solution describing field of an isolated massive body at rest, the scalar function $ϕ$ characterising the field acts as a gravitational potential as well as it curves space part o

M. Welling

Using a PASCAL program to follow the evolution of two gravitating particles in 2+1 dimensions we find solutions in which the particles wind around one another indefinitely. As their center of mass moves `tachyonic' they form a Gott-pair. To avoid unphysical boundary conditions we consider a large but closed universe. After the particles have evolved for

Merced Montesinos-Velasquez, Hugo A. Morales-Tecotl, Tonatiuh Matos

An essential step towards the identification of a fermion mass generation mechanism at Planck scale is to analyse massive fermions in a given quantum gravity framework. In this letter the two mass terms entering the Hamiltonian constraint for the Einstein-Majorana system are studied in the loop representation of quantum gravity and fermions. One resembles a

A. Katok, R. J. Spatzier

We show that most homogeneous Anosov actions of higher rank Abelian groups are locally smoothly rigid (up to an automorphism). This result is the main part in the proof of local smooth rigidity for two very different types of algebraic actions of irreducible lattices in higher rank semisimple Lie groups: (i) the Anosov actions by automorphisms of tori and ni

Ken'ichi Takano, Kazuhiro Sano

We report a novel practical method to determine exchange parameters by using experimental susceptibility data in a relatively narrow temperature region and a low order high-temperature-expansion equation. This method is applied to a square lattice and a CaV_4O_9-type lattice, and its accuracy is discussed.

V. Bayot, E. Grivei, J. -M. Beuken, S. Melinte

Thermal measurements on a GaAs/AlGaAs heterostructure reveal that the state of the confined two-dimensional electrons dramatically affects the nuclear-spin diffusion near Landau level filling factor ν=1. The experiments provide quantitative evidence that the sharp peak in the temperature dependence of heat capacity near ν=1 is due to an enhanced nuclear-spin

M. Kirkengen, Yu. M. Galperin

A theory of weakly-nonlinear low-temperature relaxational absorption of acoustic and electromagnetic waves in dielectric and metallic glasses is developed. Basing upon the model of two-level tunneling systems we show that the nonlinear contribution to the absorption can be anomalously large. This is the case at low enough frequencies, where freqeuency times

W. E. Pickett

The strong corrugation of the V4O9 layer in the spin gap system CaV4O9 is examined for its impact on the exchange coupling constants between the spin 1/2 V ions. Local spin density (LSD) calculations show that the V spin occupies a d(x^2-y^2) orbital (x and y are the V-V directions). The Kanamori-Goodenough superexchange rules, and the degeneracy of ferromag

M. Dineykhan, R. G. Nazmitdinov

Two interacting electrons in a harmonic oscillator potential under the influence of a perpendicular homogeneous magnetic field are considered. Analytic expressions are obtained for the energy spectrum of the two- and three-dimensional cases. Exact conditions for phase transitions due to the electron-electron interaction in a quantum dot as a function of the

R. W. Noyes, S. Jha, S. G. Korzennik, M. Krockenberger

We report the discovery of near-sinusoidal radial velocity variations of the G0V star rhoCrB, with period 39.6 days and amplitude 67 m/s. These variations are consistent with the existence of an orbital companion in a circular orbit. Adopting a mass of 1.0 M(Sun) for the primary, the companion has minimum mass about 1.1 Jupiter masses, and orbital radius abo

Brian A. Vaughan, Michiel van der Klis, Mariano Mendez, Jan van Paradijs

Using the Rossi X-ray Timing Explorer we have measured 27 microsecond time delays in 830 Hz quasi-periodic oscillations (QPO) between 4-6 keV and 11-17 keV in 4U 1608-52, with high-energy photons lagging low energy photons, and found upper limits to the time delays of 45 microseconds between 2-6.5 keV and 6.5-67 keV in 730 Hz QPO in 4U 0614+091 and 30 micros

Bennett Link, Richard I. Epstein

We show that the brighter gamma-ray bursts (GRBs) in the BATSE 3B catalog concentrate slightly toward the Galactic plane and center, suggesting that at least some bursts originate within the Galaxy. To develop an interpretation of this brightness-dependent anisotropy, we consider GRBs distributed in a thick disk centered on the Galaxy. As an approximation to

H. Liang, J. M. Dickey, G. Moorey, R. D. Ekers

We present a search for the hyperfine transition of the 57Fe+23 ion at 3.071 mm in clusters of galaxies with the ATNF Mopra telescope. The results are compared with a realistic estimate of the peak brightness temperature of the line in a cooling flow cluster A85, using the available X-ray data.

István Szapudi, Alexander S. Szalay

A class of improved estimators is proposed for N-point correlation functions of galaxy clustering, and for discrete spatial random processes in general. In the limit of weak clustering, the variance of the unbiased estimator converges to the continuum value much faster than with any alternative, all terms giving rise to a slower convergence exactly cancel. E

C. Moran, T. R. Marsh, A. Bragaglia

We have discovered that the detached double degenerate binary WD 0957-666 has an orbital period of 1.46 hours, rather than the 1.15 day orbital period reported earlier. This is the shortest period example of such a system yet discovered. We obtain a unique period, which fits both our and earlier data. At this period the emission of gravitational radiation wi

Eric G. Blackman

Observations show that magnetic reconnection and its slow shocks occur in solar flares. The basic magnetic structures are similar for long duration event (LDE) flares and faster compact impulsive (CI) flares, but the former require less non-thermal electrons than the latter. Slow shocks can produce the required non-thermal electron spectrum for CI flares by

Maurizio Salaris, Achim Weiss

Using up-to-date stellar models and isochrones we determine the age of 25 galactic halo clusters. The clusters are distributed into four groups according to metallicity. We measure the absolute age of a reference cluster in each group, and then find the relative ages of the other clusters relative to this one. This combination yields the most reliable result

V. Pirronello, O. Biham, C. Liu, L. Shen

We report on laboratory measurements of molecular hydrogen formation and recombination on an olivine slab as a function of surface temperature under conditions relevant to those encountered in the interstellar medium. On the basis of our experimental evidence, we recognize that there are two main regimes of H coverage that are of astrophysical importance; fo

F. Hamann, T. Barlow, R. D. Cohen, V. Junkkarinen

We discuss the identification and kinematics of intrinsic narrow-line absorbers in three QSOs. The line-of-sight ejection velocities in the confirmed intrinsic systems range from 1500 to 51,000 km/s. The ratio of ejection velocity to line width, V/Delta-V, in these systems ranges from ~3 to 60, in marked contrast to the BALs where typically V/Delta-V ~ 1. We

Vincent Mercat

We deal with the Brill-Noether problem for stable vector bundles of slope between one and two.

E. Izadi

Van Geemen and van der Geer, Donagi, Beauville and Debarre proposed characterizations of the locus of jacobians which use the linear system of $2Θ$-divisors. We give new evidence for these conjectures in the case of Prym varieties.

Nicholas J. Ramer, E. J. Mele, A. M. Rappe

In this paper, we develop a rigorous formulation of the local stress field. This approach can be used in conjuction with any first-principles method to study stress fields in complex bonded systems. In particular we investigate the induced stress fields resulting from homogeneous deformations for tetragonal PbTiO_3 and rhombohedral PbZrO_3. As an extension o

Mihir P. Worah

We study the flavor physics implications of baryogenesis in the Minimal Supersymmetric Standard Model. Enhanced $B-\bar B$ mixing and $b \to s γ$ rates are generic to all scenarios. Depending on the origin of the CP violating phase responsible for baryogenesis there could be a large neutron electric dipole moment, large CP violating $D-\bar D$ mixing or CP v

Soo-Jong Rey

Following recent proposal of Dijkgraaf, Verlinde and Verlinde, we show that the M(atrix) theory compactified on $S_1/Z_2$ provides with a non-perturbative description of second-quantized light-cone heterotic string. This so-called heterotic M(atrix) string theory is defined by two-dimensional (8,0) supersymmetric chiral gauge theory with gauge group SO(2N) i

M. Gürtler, E. -M. Ilgenfritz, A. Schiller

We give a more precise characterisation of the end of the electroweak phase transition in the framework of the effective 3d SU(2)--Higgs lattice model than has been given before. The model has now been simulated at gauge couplings beta_G=12 and 16 for Higgs masses M_H^*=70, 74, 76 and 80 GeV up to lattices 96^3 and the data have been used for reweighting. Th

W. C. Haxton

I consider phenomenological changes in the standard solar model with the goal of testing recent claims that the solar neutrino puzzle requires new particle physics. The assumption of a steady-state sun producing the correct luminosity and governed by standard microphysics appears to leave only one nonstandard solar model possibility open, slow mixing of the

J. W. Moffat

Models of superdense star clusters at the center of galaxies are investigated to see whether such objects can be stable and long-lived based on evaporation and collision time-scales and stability criteria. We find that physically reasonable models of massive clusters of stellar remnants can exist with masses $\geq 10^6 M_{\odot}$, which could simulate black

Dierk Bormann

The dynamics of a globally neutral system of diffusing Coulomb charges in two dimensions, driven by an applied electric field, is studied in a wide temperature range around the Berezinskii-Kosterlitz-Thouless transition. I argue that the commonly accepted ``free particle drift'' mechanism of charge transport in this system is limited to relatively lo

G. Hiller, E. O. Iltan

We present leading logarithmic QCD corrections to the decay B_s --> γγin the Standard Model. Further, the form factor F_{1}(0) of B_s --> ϕγis calculated in the framework of QCD sum rules and found to be in agreement with the result existing in the literature. Using Vector Meson Dominance model, the amplitude for B_s --> ϕγ-->γγis calculated as an estimate o

D. Yu. Peressounko, Yu. E. Pokrovsky

Hadrons emitted by the pre-surface layer of quark-gluon plasma (QGP) before phase transition into hadronic gas are considered as possible source of direct information about QGP. It is shown that these hadrons dominate at soft p_t if QGP is created in ultrarelativistic heavy ion collisions.

Marco Cavaglia, Vittorio de Alfaro, Alexandre T. Filippov

In classical two-dimensional pure dilaton gravity, and in particular in spherically symmetric pure gravity in d dimensions, the generalized Birkhoff theorem states that, for a suitable choice of coordinates, the metric coefficients are only functions of a single coordinate. It is interesting to see how this result is recovered in quantum theory by the explic

B. Tomasik, U. Heinz, U. A. Wiedemann, Y. -F. Wu

We present the Yano-Koonin-Podgoretskii parametrisation of the correlation function. Compared to the conventionally used Cartesian parametrisation, this one provides more straightforward measurement of the duration of the emission process in the fireball and a clearer signal of the longitudinal expansion, which is expected in ulrarelativistic heavy ion colli

Atro Voutilainen, Lluis Padro

We describe the use of energy function optimization in very shallow syntactic parsing. The approach can use linguistic rules and corpus-based statistics, so the strengths of both linguistic and statistical approaches to NLP can be combined in a single framework. The rules are contextual constraints for resolving syntactic ambiguities expressed as alternative

Asher Peres

The Wheeler-DeWitt equation is based on the use of canonical quantization rules that may be inconsistent for constrained dynamical systems, such as minisuperspaces subject to Einstein's equations. The resulting quantum dynamics has no classical limit and it suffers from the infamous ``problem of time.'' In this article, it is shown how a dynamica

K. -I. Izawa

We consider gauge-mediated models of supersymmetry (SUSY) breaking with strongly coupled nonabelian messenger gauge theory. After integrating out the SUSY-breaking and messenger sectors, we directly see that the effective Kahler potential transmits the SUSY breaking to the standard model sector.

J. Feinberg, A. Zee

We apply the recently introduced method of hermitization to study in the large $N$ limit non-hermitean random matrices that are drawn from a large class of circularly symmetric non-Gaussian probability distributions, thus extending the recent Gaussian non-hermitean literature. We develop the general formalism for calculating the Green's function and aver

Unal Goktas, Willy Hereman, Grant Erdmann

A new method for the computation of conserved densities of nonlinear differential-difference equations is applied to Toda lattices and discretizations of the Korteweg-de Vries and nonlinear Schrodinger equations. The algorithm, which can be implemented in computer algebra languages such as Mathematica, can be used as an indicator of integrability.

R. Gielerak, L. Jakobczyk, R. Olkiewicz

We consider quasi-free stochastically positive ground and thermal states on Weyl algebras in Euclidean time formulation. In particular, we obtain a new derivation of a general form of thermal quasi-free state and give conditions when such state is stochastically positive i.e. when it defines periodic stochastic process with respect to Euclidean time, so call

Attila Csoto

A comment on the importance of core polarization in halo nuclei. I point out that although core polarization is suppressed in neutron halos, it plays an essential role in their binding mechanism.

Attila Csoto

The importance of the Be7(p,gamma)B8 reaction in predicting the high-energy solar neutrino flux is discussed. I present a microscopic eight-body model and a potential model for the calculation of the Be7(p,gamma)B8 cross section.

A. Kievsky, E. Pace, G. Salme`, M. Viviani

The electromagnetic inclusive responses of polarized $^{3}$He and $^{3}$H are thoroughly investigated at the quasielastic peak for squared momentum transfers up to $2 (GeV/c)^2$, within the plane wave impulse approximation. Great emphasys is put on the effects in the bound-state due to different two- and three-body nuclear forces, and to the Coulomb interact

G. C. Hillhouse, B. I. S van der Ventel, S. M. Wyngaardt, P. R. de Kock

Within the relativistic PWIA, spin observables have been recalculated for quasielastic ($\vec p,\vec p '$) and ($\vec p,\vec n$) reactions on a $^{40}$Ca target. The incident proton energy ranges from 135 to 300 MeV while the transferred momentum is kept fixed at 1.97 fm^{-1}. In the present calculations, new Horowitz-Love--Franey relativistic NN amplitu

E. Suraud, P. G. Reinhard

We present the first realization of Stochastic TDHF, a theory which goes beyond pure mean-field dynamics, embracing dissipation as well as fluctuations. Applications to heavy-ion collisions in the Fermi energy domain are given and analyzed in terms of dissipative features and Intermediate Mass Fragment production.

K. Saito, K. Tsushima, A. W. Thomas

The quark-meson coupling (QMC) model is examined using Georgi's ``naive dimensional analysis''. We argue that the QMC model is quite natural as an effective field theory for nuclei.

L. Girardello, M. Porrati, A. Zaffaroni

We present a spontaneously broken N=2 supergravity model that reduces in the flat limit to a globally supersymmetric N=2 system with explicit soft supersymmetry breaking terms. These soft terms generate a mass O(100 GeV) for mirror quarks and leptons, while leaving the physical fermions light, thereby overcoming one of the major obstacles towards the constru

Matthias Burkardt

In the context of simple models, it is shown that demanding finiteness for physical masses with respect to a longitudinal cutoff, can be used to fix the ambiguity in the renormalization of fermions masses in the Hamiltonian light-front formulation. Difficulties that arise in applications of finiteness conditions to discrete light-cone quantization are discus

Martin Cederwall

The action for an 11-dimensional supermembrane contains a chiral Wess-Zumino-Witten model coupling to the E8 super-Yang-Mills theory on the end-of-the-world 9-brane. It is demonstrated that this boundary string theory is dictated both by gauge invariance and by kappa-symmetry.

V. G. Ksenzov

It was shown that the non-perturbative properties of the vacuum are described by the quantum fluctuations around the classical background with zero canonical momentum. The vacuum state has been built and checked in the framework of the sigma models in two dimentions.

David H. Adams

A refined expression for the Faddeev-Popov determinant is derived for gauge theories quantised around a reducible classical solution. We apply this result to Chern-Simons perturbation theory on compact spacetime 3-manifolds with quantisation around an arbitrary flat gauge field isolated up to gauge transformations, pointing out that previous results on the f

Samir D. Mathur

We consider the absorption of higher angular momentum modes of scalars into black holes, at low energies, and ask if the resulting cross sections are reproduced by a D-brane model. To get the correct dependence on the volume of the compactified dimensions, we must let the absorbing element in the brane model have a tension that is the geometric mean of the t

William H. Kinney, Antonio Riotto

We propose a new class of inflationary models in which the scalar field potential governing inflation is generated by the same non-perturbative gauge dynamics that may lead to supersymmetry breaking. Such models satisfy constraints from cosmic microwave background measurements for natural values of the fundamental parameters in the theory. In addition, they

L. A. Anchordoqui, M. T. Dova, L. N. Epele, J. D. Swain

In this work we re-examine the opacity of the cosmic background radiation to the propagation of extremely high energy cosmic rays. We use the continuous energy loss approximation to provide spectral modification factors for several hypothesized cosmic ray sources. Earlier problems with this approximation are resolved including the effects of resonances other

J. Edsjo

Neutralino dark matter, and in particular different aspects of its detection at neutrino telescopes, has been studied within the Minimal Supersymmetric extension of the Standard Model, the MSSM. The relic density of neutralinos has been calculated using sophisticated routines for integrating the annihilation cross section and the Boltzmann equation. As a new

Bo Andersson, Markus Ringner

By providing the Lund Model fragmentation process with a quantum-mechanical framework we extend the results of previous work to situations where there are very many identical bosons. We investigate the features of the weight distributions in some detail and in particular exhibit three-particle BE-correlations, the influence on the rho-spectrum and the differ

Myunggyu Kim, Dong-Pil Min

We calculate the electric polarizability $α(q^2)$ of the proton in virtual Compton scattering using the Skyrme model. The $q^2$ dependence of the polarizability is comparable with the predictions obtained from the non-relativistic quark model and the linear sigma model. The chiral behaviors of our $α(0)$ and $d^2α(0)/d^2q^2$ agree with the results of the chi

Stanley J. Brodsky, Marek Karliner

An outstanding mystery of charmonium physics is why the J/ψdecays prominently to pseudoscalar plus vector meson channels, such as J/ψ-> ρπand J/ψ-> K^*K, whereas the ψ'(2S) does not. We show that such decays of J/ψand their suppression for ψ'(2S) follow naturally from the existence of intrinsic charm |qbar q cbar c> Fock components of the light vecto

G. Cella, U. M. Heller, V. K. Mitrjushkin, A. Vicere

We study the heavy charge potential in the Coulomb phase of pure gauge compact U(1) theory on the lattice. We calculate the static potential $V_W(T,{\vec R})$ from Wilson loops on a $16^3 \times 32$ lattice and compare with the predictions of lattice perturbation theory. We investigate finite size effects and, in particular, the importance of non-Coulomb con

I. Ciufolini, D. Lucchesi, F. Vespe, F. Chieppa

Rotation of a body, according to Einstein's theory of general relativity, generates a "force" on other matter; in Newton's gravitational theory only the mass of a body produces a force. This phenomenon, due to currents of mass, is known as gravitomagnetism owing to its formal analogies with magnetism due to currents of electric charge. Theref

Werner M. Vieira, Patricio S. Letelier

We stress that halo dipole components are nontrivial in core-halo systems in both Newton's gravity and General Relativity. To this end, we extend a recent exact relativistic model to include also a halo dipole component. Next, we consider orbits evolving in the inner vacuum between a monopolar core and a pure halo dipole and find that, while the Newtonia

J. Carot, L. A. Núnez, U. Percoco

We present the general structure of proper Ricci Collineations (RC) for type B warped space-times. Within this framework, we give a detailed description of the most general proper RC for spherically symmetric metrics. As examples, static spherically symmetric and Friedmann-Robertson-Walker space-times are considered.

R. R. Zapatrin

An algebraic scheme is suggested in which discretized spacetime turns out to be a quantum observable. As an example, a toy model producing spacetimes of four points with different topologies is presented. The possibility of incorporating this scheme into the framework of non-commutative differential geometry is discussed.

Burkhard Kleihaus, Jutta Kunz

We construct a new class of asymptotically flat black hole solutions in Einstein-Yang-Mills and Einstein-Yang-Mills-dilaton theory. These black hole solutions are static, and they have a regular event horizon. However, they possess only axial symmetry. Like their regular counterparts, the black hole solutions are characterized by two integers, the winding nu

Paolo Bertozzini, Roberto Conti, Roberto Longo

We consider a Moebius covariant sector, possibly with infinite dimension, of a local conformal net of von Neumann algebras on the circle. If the sector has finite index, it has automatically positive energy. In the infinite index case, we show the spectrum of the energy always to contain the positive real line, but, as seen by an example, it may contain nega

P. Phillips, Y. Wan

We suggest here that the recently-reported ``insulator-metal transition'' in Si MOSFET's is consistent instead with a transition from an insulator to a T=0 p-wave superconducting state.

B. E. Vugmeister, J. Botina, H. Rabitz

The tails of prehistory probability density in nonlinear multistable stochastic systems driven by white Gaussian noise, which has been a subject of recent study, are analyzed by employing the concepts of nonstationary optimal fluctuations. Results of numerical simulations evidence that the prehistory probability density is non-Gaussian and highly asymmetrica

J. T. Chalker, Z. Jane Wang

We study spectral properties of the Fokker-Planck operator that describes particles diffusing in a quenched random velocity field. This random operator is non-Hermitian and has eigenvalues occupying a finite area in the complex plane. We calculate the eigenvalue density and averaged one-particle Green's function, for weak disorder and dimension d>2. We r

Xiaohui Wang, Reinhold Egger, Hermann Grabert

The Coulomb energy of a small metallic island coupled to an electrode by a tunnel junction is investigated. We employ Monte Carlo simulations to determine the effective charging energy for arbitrary tunneling strength. For small tunneling conductance, the data agree with analytical results based on a perturbative treatment of electron tunneling, while for ve

E. V. Sukhorukov, A. V. Khaetskii

We consider the influence of the electron-electron interaction on the nonlinearity of the current-voltage characteristic of the tunnel junction at low bias (diffusive anomaly) in the presence of the classical magnetic field. We present the theory of a new phenomenon which manifests itself in the strong anisotropy of a diffusive anomaly for different orientat

I. L. Aleiner, B. L. Altshuler

We study the tunneling density of states (DoS) in the superconducting systems driven by Zeeman splitting E_Z into the paramagnetic phase. We show that, even though the BCS gap disappears, superconducting fluctuations cause a strong DoS singularity in the vicinity of energies -E^* for electrons polarized along the magnetic field and E^* for the opposite polar

W. Ziegler, H. Endres, W. Hanke

We study the interplay of correlations and disorder using an unrestricted Slave-Boson technique in real space. Within the saddle-point approximation, we find Friedel oscillations of the charge density in the vicinity of a nonmagnetic impurity, in agreement with numerical simulations. The corresponding amplitudes are suppressed by repulsive interactions, whil

Keith Slevin, Tomi Ohtsuki

We report a finite size scaling study of the Anderson transition. Different scaling functions and different values for the critical exponent have been found, consistent with the existence of the orthogonal and unitary universality classes which occur in the field theory description of the transition. The critical conductance distribution at the Anderson tran

Peter A. Heeman, James F. Allen

To understand a speaker's turn of a conversation, one needs to segment it into intonational phrases, clean up any speech repairs that might have occurred, and identify discourse markers. In this paper, we argue that these problems must be resolved together, and that they must be resolved early in the processing stream. We put forward a statistical langua

M. B. Bell, P. A. Feldman, M. J. Travers, M. C. McCarthy

Two consecutive rotational transitions of the long cyanopolyyne HC11N, J=39-38, and J=38-37, have been detected in the cold dust cloud TMC-1 at the frequencies expected from recent laboratory measurements by Travers et al. (1996), and at about the expected intensities. The astronomical lines have a mean radial velocity of 5.8(1) km/s, in good agreement with

Uros Seljak, Ue-Li Pen, Neil Turok

We compute the polarization power spectra for global strings, monopoles, textures and nontopological textures, and compare them to inflationary models. We find that topological defect models predict a significant (1 microK) contribution to magnetic type polarization on degree angular scales, which is produced by the large vector component of the defect sourc

Martijn de Kool

This paper reviews the dynamical models that have been proposed for the outflows that are responsible for the broad blue-shifted absorption features observed in broad absorption line quasars and in some Seyfert galaxies.

R. A. D. Wijnands, M. van der Klis, E. Kuulkers, K. Asai

We analysed all X-ray data on the low-mass X-ray binary Cygnus X-2 obtained with Ginga. The analysis of the spectral and fast timing behaviour of these 4 years of data provides new insights in the behaviour of this Z source. We confirm the previously observed recurrent patterns of behaviour in the X-ray colour-colour and hardness-intensity diagrams (HIDs) co

A. Udalski, A. Olech, M. Szymanski, J. Kaluzny

We present the fifth part of the OGLE Catalog of Periodic Variable Stars in the Galactic bulge. 574 variable stars: 44 pulsating, 369 eclipsing and 161 miscellaneous type were detected in four fields located symmetrically in galactic lattitude around the Galactic center: MM5-A, MM5-B, MM7-A and MM7-B. The Catalog and individual observations are available in

Bono Giuseppe, Caputo Filippina, Cassisi Santi, Castellani Vittorio

We investigate the evolutionary behavior of stellar structures with metallicity Z=0.04 in order to disclose theoretical expectations for both evolutionary and pulsational behaviors of Super-Metal-Rich (SMR) objects, which are found in the solar neighborhood, in the Galactic bulge and in elliptical galaxies. We find that at the exhaustion of central helium SM

Jan-e Alam, Sibaji Raha, Bikash Sinha

The cosmic first order phase transition from quarks to hadrons, occurring a few microseconds after the Big Bang, would lead to the formation of quark nuggets which would be stable on a cosmological time scale, if the associated baryon number is larger than a critical value. We examine the possibility that these surviving quark nuggets may not only be viable

Ralph A. M. J. Wijers, Steinn Sigurdsson

Markwardt and Oegelman (1995) used ROSAT to reveal a 12 by 45 arcmin structure in 1 keV X rays around the Vela pulsar, which they interpret as a jet emanating from the pulsar. We here present an alternative view of the nature of this feature, namely that it consists of material from very deep inside the exploding star, close to the mass cut between material

T. Padmanabhan, Sunu Engineer

We discuss the late time evolution of the gravitational clustering in an expanding universe, based on the nonlinear scaling relations (NSR) which connect the nonlinear and linear two point correlation functions. The existence of critical indices for the NSR suggests that the evolution may proceed towards a universal profile which does not change its shape at

James M. Stone

The nonlinear evolution of unstable C-type shocks in weakly ionized plasmas is studied by means of time-dependent magnetohydrodynamical simulations. This study is limited to shocks in magnetically dominated plasmas (in which the Alfven speed in the neutrals greatly exceeds the sound speed), and microphysical processes such as ionization and recombination are

Jeongnim Kim, Lin-Wang Wang, Alex Zunger

We have contrasted the quantum confinement of (i) multiple quantum wells of flat GaAs and AlAs layers, i.e. $(\GaAs)_{m}/(\AlAs)_n/(\GaAs)_p/(\AlAs)_q$, with (ii) ``cylindrical Russian Dolls'' -- an equivalent sequence of wells and barriers arranged as concentric wires. Using a pseudopotential plane-wave calculation, we identified theoretically a set

Peter E. Haagensen, Kasper Olsen

Manifest T-duality covariance of the one-loop renormalization group flows is shown for a generic bosonic sigma model with an abelian isometry, by referring a set of previously derived consistency conditions to the tangent space of the target. For a restricted background, T-duality transformations are then studied at the next order, and the ensuing consistenc

Nancy P. Sandler, Claudio de C. Chamon, Eduardo Fradkin

We study the reflection of electrons and quasiparticles on point-contact interfaces between fractional quantum Hall (FQH) states and normal metals (leads), as well as interfaces between two FQH states with mismatched filling fractions. We classify the processes taking place at the interface in the strong coupling limit. In this regime a set of quasiparticles

Roy Maartens, Bruce A. Bassett

We develop and apply a fully covariant 1+3 electromagnetic analogy for gravity. The free gravitational field is covariantly characterized by the Weyl gravito-electric and gravito-magnetic spatial tensor fields, whose dynamical equations are the Bianchi identities. Using a covariant generalization of spatial vector algebra and calculus to spatial tensor field

Marco Lombardi, Giuseppe Bertin

Different options can be used in order to measure the shear from observations in the context of weak lensing. Here we introduce new methods where the isotropy assumption for the distribution of the source galaxies is implemented directly on the observed quadrupole moments. A quantitative analysis of the error associated with the finite number of source galax