September 1999 arXiv papers — page 5

Stacy McGaugh

The rotation curves of disk galaxies exhibit a number of striking regularities. The amplitude of the rotation is correlated with luminosity (Tully-Fisher), the shape of the rotation curve is well predicted by the luminous mass distribution, and the magnitude of the mass discrepancy increases systematically with decreasing centripetal acceleration. These prop

J. Siebert, W. Brinkmann, M. Gliozzi, S. A. Laurent-Muehleisen

We present 6 ASCA and SAX observations of 4 intermediate BL Lac objects (1034+5727, 1055+5644, 1424+2401, 1741+1936). Their X-ray spectral properties and spectral energy distributions are compared to typical X-ray and radio selected BL Lacs. 1055+5644 varied by a factor of ten in flux without significant spectral changes.

J. Siebert, N. Kawai, W. Brinkmann

We investigate the X-ray properties of the powerful radio galaxy Hercules A (3C 348) using ROSAT HRI, PSPC and ASCA observations. The ASCA data are well fit by a thermal plasma model with a temperature of about 4.3 keV and abundances 0.4 solar. The HRI observation clearly reveals extended and elongated X-ray emission. For radii greater than 10 arcsec, the su

F. Grundahl, M. Catelan, W. B. Landsman, P. B. Stetson

We study the ``jump'' in the blue horizontal--branch (BHB) distribution first detected by Grundahl et al. (1998) in the Galactic globular cluster (GC) M13. On the basis of Stromgren photometry for a sample of fourteen GC's we show that: 1) The jump is best characterized as a systematic shift, on a (u, u-y) color-magnitude diagram, from canonical

F. Grundahl, D. A. VandenBerg, P. B. Stetson, M. I. Andersen

We illustrate the application of high precision Stromgren uvby photometry to open and globular clusters (GCs). It is shown how such data can be used to determine cluster ages, independent of distance and only weakly dependent on reddening. We also illustrate in detail how c1 index variations point to significant star-to-star abundance variations of C and N (

R. P. Saglia, Andi Kronawitter, Ortwin Gerhard, Ralf Bender

Accurate and radially extended stellar kinematic data reaching R=97&#39;&#39; from the center are presented for the cD galaxy of Fornax, NGC 1399. The stellar rotation is small (<= 30 km/s); the stellar velocity dispersion remains constant at 250-270 km/s. The deviations from Gaussian line of sight velocity distributions are small, at the percent level. We c

C. Marinoni, G. Giuricin, L. Ceriani, A. Pisani

We discuss the 3D real-space reconstruction of the optical galaxy density field in the local Universe as derived from the galaxies of the Nearby Optical Galaxy (NOG) sample. NOG is a distance-limited (cz_{LG} < 6000 km/s) and magnitude--limited (B<14 mag) sample of 7076 optical galaxies which covers 2/3 (8.29 sr) of the sky (|b|>20). We have replaced ``true

Gunnar Hornig

Newly emerging magnetic flux can show a complicated linked or interwoven topology of the magnetic field. The complexity of this linkage or knottedness of magnetic flux is related to the free energy stored in the magnetic field. Magnetic reconnection provides a process to release this energy on the time scale of the dynamics. At the same time it approximately

A. C. Donea, Heino Falcke, P. L. Biermann

We investigate various models of accretion disks for Sgr A*, one of the most puzzling sources in the Galaxy. The generic image we have taken into account consists of a black hole, an accretion disk, and a jet. Various accretion models are able to explain the low NIR flux of Sgr A*: a standard accretion disk with a jet, an ADAF, or an EDAF (Ejection Dominated

Heino Falcke

Results of two years of continuous monitoring of flux density variations at 8.3 and 2.3 GHz of the Galactic Center super-massive black hole candidate Sgr A* are reported. The average RMS modulation indices are 6% and 2.5% at 8.3 & 2.3 GHz respectively. There is a certain degree of correlation between both frequencies. The timescale of variability at 8.3 & 2.

C. Charbonnel, P. A. Denissenkov, A. Weiss

We present the evolution of low mass and low metallicity RGB models computed under the assumption of deep mixing between the convective envelope and the hydrogen burning shell. We discuss the helium enrichment of the envelope which is necessary or allowed to achieve or to keep consistency with the observations, and conclude on the possible connection between

Heino Falcke

In this paper the jet model for the supermassive black hole candidate Sgr A* in the Center of the Galaxy is reviewed. The most recent model, with a reduced set of parameters, is able to account for all major radio properties of the source: size, structure, flux density, and spectrum. The model requires a minimum jet power of ~10^39 erg/sec and in a symbiotic

Claude Bertout, Noel Robichon, Frederic Arenou

We cross-correlate the Herbig & Bell and Hipparcos Catalogues in order to extract the results for young stellar objects (YSOs). We compare the distances of individual young stars and the distance of their presumably associated molecular clouds, taking into account post-Hipparcos distances to the relevant associations and using Hipparcos intermediate astromet

S. H. Rhie

Planetary systems toward the Galactic Bulge can be detected through microlensing measurements. The microlensing planet search technique has some unique merits: low-mass planets can be detected from the ground; the Galactic family of planetary systems can be sampled unbiased; the time scale for the completion of each event is relatively short. The unambiguity

P. Salati, R. Taillet, E. Aubourg, N. Palanque-Delabrouille

Recent observations give some clues that the lenses discovered by the microlensing experiments in the direction of the Magellanic Clouds may be located in these satellite galaxies. We re-examine the possibility that self-lensing alone may account for the optical depth measured towards the Large Magellanic Cloud (LMC). We present a self-consistent multi-compo

Shane L. Larson, William A. Hiscock, Ronald W. Hellings

To determine whether particular sources of gravitational radiation will be detectable by a specific gravitational wave detector, it is necessary to know the sensitivity limits of the instrument. These instrumental sensitivities are often depicted (after averaging over source position and polarization) by graphing the minimal values of the gravitational wave

Sergei Sakovich

We use the Calogero equation to illustrate the following two aspects of the Painleve analysis of nonlinear PDEs. First, if a nonlinear equation passes the Painleve test for integrability, the singular expansions of its solutions around characteristic hypersurfaces can be neither single-valued functions of independent variables nor single-valued functionals o

Arnold Neumaier

In this sequence of papers, noncommutative analysis is used to give a consistent axiomatic approach to a unified conceptual foundation of classical and quantum physics. The present Part I defines the concepts of observables, states and ensembles, clarifies the logical relations and operations for them, and shows how they give rise to dynamics and probabiliti

Alexander D. Panov

It was shown that different mechanisms of perturbation of spontaneous decay constant: inelastic interaction of emitted particles with particle detector, decay onto an unstable level, Rabi transition from the final state of decay (electromagnetic field domination) and some others are really the special kinds of one general effect - perturbation of decay const

Robert R. Tucci

We propose a new measure of quantum entanglement. Our measure is defined in terms of conditional information transmission for a Quantum Bayesian Net. We show that our measure is identically equal to the Entanglement of Formation in the case of a bipartite (two listener) system occupying a pure state. In the case of mixed states, the relationship between thes

Brandon Carter

After a brief explanation of the concept of a vorton, quantitative estimates of the vorton population that would be produced in various cosmic string scenarios are reviewed. Attention is drawn to previously unconsidered mechanisms that might give rise to much more prolific vorton formation that has been envisaged hitherto.

Helmut Satz, Dinesh Kumar Srivastava

We determine the time evolution of the colour screening mass in high energy nuclear collisions, as provided by the parton cascade model. Using our result, we discuss the onset of deconfinement and the onset of quarkonium suppression in a general, not necessarily equilibrated environment of strongly interacting constituents.

Andre Rouge

The measurements of the CP violation parameters by the CPLEAR experiment are reviewed. It is shown that attempts to prove T-violation from the semileptonic asymmetries are flawed by logical inconsistencies.

N. Chandrasekhar

Two dimensional films comprising of Bi clusters ranging in size from 25 to 100 $\mathrmÅ$ show an influence of the underlying matrix on normal state resistivity and the superconducting transition temperature $T_\mathrm{c}$. This is in contrast to crystalline Bi. Quantum size effects are observed by changing the deposition temperature, which determines cluste

G. Sambandamurthy, K. DasGupta, N. Chandrasekhar

We report an experimental study of quench condensed ($2K\le T \le 15K$) disordered ultrathin films of {\rm Bi} where localisation effects and superconductivity compete. Experiments are done with different substrates and/or different underlayers. Quasi-free standing films of {\rm Bi}, prepared by quenching {\rm Bi} vapours onto solid {\rm Xe}, are also studie

J. Einasto, M. Einasto

A short story of dark matter as an example of a scientific revolution is given. The characteristics of stellar populations are compared with those of dark halos. The mean mass-to-luminosity ratio of stellar populations is found to be 4 in Solar units. Dark matter around galaxies, and in groups, clusters and voids is discussed. Modern data suggest that the ov

J. Einasto

The mean power spectrum of galaxies is compared with theoretical models. Possibilities to explain the observed power spectrum are discussed. Superclusters and voids form a quasi-regular lattice of mean cell size 120 Mpc; the main axis of the lattice is directed toward the supergalactic Y coordinate. Principal conclusions are that on scales around 100 Mpc the

Vladimir V. Usov

Relativistic strongly magnetized winds outflowing from fast-rotating compact objects like millisecond pulsars with surface magnetic fields of $\sim 10^{15}-10^{16}$ G are plausible sources of cosmological $γ$-ray bursts. In such winds, there are at least three regions where extremely powerful X-ray and $γ$-ray emission may be generated. The first radiating r

M. J. Page, F. J. Carrera

We show that binned differential luminosity functions constructed using the 1/Va method have a significant systematic error for objects close to their parent sample&#39;s flux limit(s). This is particularly noticeable when luminosity functions are produced for a number of different redshift ranges as is common in the study of AGN or galaxy evolution. We pres

R. Battiston, M. Biasini, E. Fiandrini, J. Petrakis

The modeled performance of the Alpha Magnetic Spectrometer (AMS) as a high energy (0.3 to 100 GeV) gamma-ray detector is described, and its gamma ray astrophysics objectives are discussed.

M. A. Wood, the XCov 15 Team

DQ Herculis was the Summer 1997 WET northern-hemisphere primary target. The O-C phase diagram of the 71-s signal reveals out-of-eclipse phase variations resulting from the self eclipses of a nearly edge-on, non-axisymmetric disc. We work the forward problem of simulating DQ Herculis numerically using the method of smoothed particle hydrodynamics (SPH), and f

Robert A. Herrmann

A method is given by which the descriptive content of quantum state information can be encoded into subparticle coordinates. This method is consistent with the MA-model solution to the general grand unification problem. Subparticle mechanisms via affine or linear transformations are also discussed.

Meng Lu, Joseph L. Birman, Carlos Trallero-Giner, Fernando de Leon-Perez

The scattering probabilities of hot excitons in narrow quantum wells (QWs)are obtained. The exciton-phonon matrix element is considered by using an envelope function Hamiltonian approach in the strong quantization limit where the QW width is smaller than the exciton bulk Bohr radius. The Fröhlich-like interaction is taken into account and the contribution of

S. Kasuya, M. Kawasaki

We present the full nonlinear calculation of the formation of a Q-ball through the Affleck-Dine (AD) mechanism by numerical simulations. It is shown that large Q-balls are actually produced by the fragmentation of the condensate of a scalar field whose potential is very flat. We find that the typical size of a Q-ball is determined by the most developed mode

Joseph S. Plewa, Thomas A. Witten

We demonstrate a variant of the Bond Fluctuation lattice Monte Carlo model in which moves through cis conformations are forbidden. Ring polymers in this model have a conserved quantity that amounts to a topological linking number. Increased linking number reduces the radius of gyration mildly. A linking number of order 0.2 per bond leads to an eight-percent

Changye Chen

In this letter we investigate the common procedure in which any wave function is expanded into a series of eigenfunctions. It is shown that as far as dynamical systems are concerned the expanding procedure involves various mathematical and physical difficulties. With or without introducing phase factors, such expansions do not represent dynamical wave functi

A. Mary Selvam, Suvarna Fadnavis

C60 molecules form spontaneously during vaporization of carbon associated with intense heating and turbulence such as in electrical arcs or flames. Self-organization of fluctuations in the highly turbulent (chaotic) atomized carbon vapor appears to result in the formation of the stable structure of C60 and therefore may be visualized as order out of chaos ph

R. Myrzakulov, A. K. Danlybaeva

The connection between differential geometry of curves and the (2+1)-dimensional integrable spin system - the M-III equation is established. Using the presented geometrical formalism the L-equivalent counterpart of the M-III equation is found.

Chengyan Liu

We solve Landau&#39;s four unattackable problems, including Goldbach Conjecture and Twin Prime Conjecture through sieve method.

Chengyan Liu

Through an equivalent condition on the Farey series set forth by Franel and Landau, we prove Riemann Hypothesis for the Riemann zeta-function and the Dirichlet L-function.

I. L. Buchbinder, I. B. Samsonov

We study the structure of holomorphic effective action for hypermultiplet models interacting with background super Yang-Mills fields. A general form of holomorphic effective action is found for hypermultiplet belonging to arbitrary representation of any semisimple compact Lie group spontaneously broken to its maximal abelian subgroup. The applications of obt

Y. Tayalati, J. Derkaoui

This work deals with the possible solution of the solar neutrino problem in the framework of the resonant neutrino spin-flavor precession scenario. The event rate results from the solar neutrino experiments as well as the recoil electron energy spectrum from SuperKamiokande are used to constrain the free parameters of the neutrino in this model. We consider

Dao-Neng Gao, Mu-Lin Yan

By employing vector meson dominance to establish the electromagnetic interactions of hadrons, the electromagnetic self-energy of the neutral pions, which receives the contributions from the vector resonances due to chiral anomaly, is evaluated. This part of the electromagentic mass, which can contribute to the mass difference of $π^\pm-π^0$, is finite and as

L3 Collaboration

We present a combined measurement of Rb = Γ(Z -> bb) / Γ(Z ->hadrons) and the semileptonic branching ratio of b quarks in Z decays, BR(b-> l nu X), using double-tag methods. Two analyses are performed on one million hadronic Z decays collected in 1994 and 1995. The first analysis exploits the capabilities of the silicon microvertex detector. The tagging of b

L3 Collaboration

A search for pair-produced charged Higgs bosons is performed with the L3 detector at LEP using data collected at a centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 176.4 pb^-1. Higgs decays into a charm and a strange quark or into a tau lepton and its associated neutrino are considered. The observed events are consistent with

L3 Collaboration

The pair production of Z bosons is studied using the data collected by the L3 detector at LEP in 1998 in e+e- collisions at a centre-of-mass energy of 189 GeV. All the visible final states are considered and the cross section of this process is measured to be 0.74 +0.15 -0.14 (stat.) +/- 0.04 (syst.) pb. Final states containing b quarks are enhanced by a ded

Claude de Calan, Flavio S. Nogueira

An unifying scenario for the critical behavior of YBa$_{2}$Cu$_{3}$O$_{7-δ}$ (YBCO) and Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+δ}$ (BSCCO) is proposed. It is shown that both critical crossovers observed in these materials follow by considering two different scalings in the dual Ginzburg-Landau model. The first scaling leads to the critical exponents $ν\approx 2/3$,

J. Bednarz, M. Ostrowski

The process of cosmic ray acceleration up to energies in excess of $10^{20}$ eV at relativistic shock waves with large Lorentz factors, $Γ\gg 1$ requires $\sim Γ^2$ particle energy gains at single reflections from the shock (cf. Gallant & Achterberg 1999). In the present comment, applying numerical simulations we address an efficiency problem arising for suc

Glenn E. Ciolek, Shantanu Basu

Recent high-resolution studies of the L1544 protostellar core by Tafalla et al. and Williams et al. reveal the structure and kinematics of the gas. The observations of this prestellar core provide a natural test for theoretical models of core formation and evolution. Based on their results, the above authors claim a discrepancy with the implied infall motion

Jorge Alfaro, Hugo A. Morales-Tecotl, Luis F. Urrutia

Massive spin-1/2 fields are studied in the framework of loop quantum gravity by considering a state approximating, at a length scale $\cal L$ much greater than Planck length $\ell_P=1.2\times 10^{-33}$cm, a spin-1/2 field in flat spacetime. The discrete structure of spacetime at $\ell_P$ yields corrections to the field propagation at scale $\cal L$. Next, Ne

V. Gorjian, E. L. Wright, R. R. Chary

The Cosmic InfraRed Background (CIRB) is the sum total of the redshifted and reprocessed short wavelength radiation from the era of galaxy formation, and hence contains vital information about the history of galactic evolution. One of the main problems associated with estimating an isotropic CIRB in the near infrared (1-5 microns) is the unknown contribution

M. C. Daflon Barrozo

Explicit relations among moduli of the Heterotic and Type IIB string theories in 8 dimensions are obtained. We identify the BPS states responsible for gauge enhancements in the type IIB theory and their dual partners in the Heterotic theory compactified with and without Wilson lines. The masses of BPS states in Type IIB string theory compactified on the base

G. I. Gomero, M. J. Reboucas, A. F. F. Teixeira

We study the topological signature of euclidean isometries in pair separations histograms (PSH) and elucidate some unsettled issues regarding distance correlations between cosmic sources in cosmic crystallography. Reducing the noise of individual PSH&#39;s using mean pair separations histograms we show how to distinguish between topological and statistical s

Donam Youm

We study the relation between the (generalized) conformal quantum mechanics of 0-branes and the two-dimensional dilaton gravity. The two-dimensional actions obtained from the supergravity effective actions for the (dilatonic) 0-branes through the compactification on a sphere are related to known two-dimensional dilaton gravity models. The SL(2,R) symmetry of

Jian-Xin Zhu, T. K. Lee, C. S. Ting, Chia-Ren Hu

The quasiparticle resonant states around a single nonmagnetic impurity with unitary scattering in a d-wave superconductor is studied by solving the Bogoliubov-de Gennes equations based on a t-J model. Both the spatial variation of the order parameter and the local density of states (LDOS) around the impurity have been investigated. We find: (i) A particle-ho

Alessandro Pelizzola

I show that the cluster variation method, long used as a powerful hierarchy of approximations for discrete (Ising-like) two-dimensional lattice models, yields exact results on the disorder varieties which appear when competitive interactions are put into these models. I consider, as an example, the plaquette approximation of the cluster variation method for

Marcos Jardim

We explore the role played by the spectral curves associated with Higgs pairs in the context of the Nahm transform of doubly-periodic instantons defined in &#34;Construction of doubly-periodic instantons&#34; (math.DG/9909069) and &#34;Nahm transform for doubly-periodic instantons&#34; (math.DG/9910120). More precisely, we show how to construct a triple cons

A. Hebecker

In these lectures, a simple introduction to the phenomenon of diffraction in deep inelastic scattering and its theoretical description is given. While the main focus is on the diffractive structure function F_2^D, some issues in diffractive vector meson production are also discussed.

Valery P. Gusynin, Vladimir V. Kornyak

Asymptotic heat kernel expansion for nonminimal differential operators on curved manifolds in the presence of gauge fields is considered. The complete expressions for the fourth coefficient E_4 in the heat kernel expansion for such operators are presented for the first time. The expressions were computed for general case of manifolds of arbitrary dimension n

Martin Freund, Tommy Ohlsson

We have investigated matter enhanced neutrino oscillations with a mantle-core-mantle step function and a realistic Earth matter density profile in both a two and a three neutrino scenario. We found that the realistic Earth matter density profile can be well approximated with the mantle-core-mantle step function and that there could be an influence on the osc

Taiichiro Saikawa, Alvaro Ferraz

A precursor effect on the Fermi surface in the two-dimensional Hubbard model at finite temperatures near the antiferromagnetic instability is studied using three different itinerant approaches: the second order perturbation theory, the paramagnon theory (PT), and the two-particle self-consistent (TPSC) approach. In general, at finite temperature, the Fermi s

Sergei V. Ketov

We consider the general hypermultiplet Low-Energy Effective Action (LEEA) that may appear in quantized, four-dimensional, N=2 supersymmetric, gauge theories, e.g. in the Coulomb and Higgs branches. Our main purpose is a description of the exact LEEA of n magnetically charged hypermultiplets. The hypermultiplet LEEA is given by the N=2 supersymmetric Non-Line

Frank Nijhoff, Andrew Hone, Nalini Joshi

We present a novel integrable non-autonomous partial differential equation of the Schwarzian type, i.e. invariant under Möbius transformations, that is related to the Korteweg-de Vries hierarchy. In fact, this PDE can be considered as the generating equation for the entire hierarchy of Schwarzian KdV equations. We present its Lax pair, establish its connecti

Stephen L. Adler

We use the Itô stochastic calculus to give a simple derivation of the Lindblad form for the generator of a completely positive density matrix evolution, by specialization from the corresponding global form for a completely positive map. As a by-product, we obtain a generalized generator for a completely positive stochastic density matrix evolution.

Matteo G A Paris

We suggest a method to prepare any chosen superposition a0 |0> + a1 |1> of the vacuum and one-photon states. The method is based on a conditional double-interferometer fed by an one-photon state and a coherent state. The scheme involves only linear optical elements and avalanche photodetectors, and therefore it should be realizable with current technology. A

Charles Francis

We describe a substructure for matter in which metric relations are not assumed as properties of a physical manifold, and instead the metric of general relativity is found in configurations of particle interactions. The &#39;state&#39; of a particle is the set of possible configurations of surrounding particles. States are thus non-local, while particles are

Peter Braun-Munzinger

We discuss recent experimental results in the field of ultra-relativistic nuclear collisions. The emerging ``picture&#39;&#39; is a collectively expanding, initially hot and dense fireball in which strangeness- and low-mass di-lepton pair production are enhanced and J/$Ψ$ production is suppressed compared to expectations from nucleon-nucleon collisions. It i

David Eppstein

Any four mutually tangent spheres in R^3 determine three coincident lines through opposite pairs of tangencies. As a consequence, we define two new triangle centers.

V. Ovsienko, S. Tabachnikov

The paper concerns discrete versions of the three well-known results of projective differential geometry: the four vertex theorem, the six affine vertex theorem and the Ghys theorem on four zeroes of the Schwarzian derivative. We study geometry of closed polygonal lines in $\bbRP^d$ and prove that polygons satisfying a certain convexity condition have at lea

James D. E. Grant, Brad Lackey

We express the first jet bundle of curves in Euclidean space as homogeneous spaces associated to a Galilean-type group. Certain Cartan connections on a manifold with values in the Lie algebra of the Galilean group are characterized as geometries associated to systems of second order ordinary differential equations. We show these Cartan connections admit a fo

L. V. Laperashvili, H. B. Nielsen

Using a one-loop approximation for the effective potential in the Higgs model of electrodynamics for a charged scalar field, we argue for the existence of a triple point for the renormalized (running) values of the selfinteraction $λ$ and the &#34;charge&#34; g given by $(λ_{run}, g^2) = (-{10/9} π^2,{4/3}\sqrt{5/3}{π^2}) \approx(-11, 17)$. Considering the b

Fiorenzo Bastianelli, Roberto Zucchini

We present a calculation of three point functions for a class of chiral operators, including the primary ones, in d = 3, N = 8; d = 6, N = (2,0) and d = 4, N = 4 superconformal field theories at large N. These theories are related to the infrared world-volume descriptions of N coincident M2, M5 and D3 branes, respectively. The calculation is done in the fram

J. Jalilian-Marian

We show estimates for shadowing of gluons at small values of $x$, appropriate to RHIC and LHC experiments using a new evolution equation which takes into account the effects of gluon recombination to all orders in gluon density. We show that there is a significant depletion in the gluon density of large nuclei.

J. B. Tausk

The non-planar Feynman diagram with seven massless, scalar propagators and four on-shell legs (the crossed double box) is calculated analytically in dimensional regularization. The non-planar diagram with six propagators is also discussed.

Yu. A. Markov, M. A. Markova

On the basis of the approximate dynamical equations describing the behavior of quark-gluon plasma (QGP) in the semiclassical limit and Yang-Mills equation, the kinetic equation for longitudinal waves (plasmons) is obtained. With the Ward identities the gauge invariance of obtained nonlinear Landau damping rate is proved. The physical mechanisms defining nonl

Jaume Guasch, Joan Sola

Flavour changing neutral decays of the top quark are know to be extremely suppressed in the SM. This is especially so for the top quark decay into the SM Higgs boson, whose rate is less than 10^-13. However, it turns out that the decay modes t->c h, with h= h^0,H^0,A^0 any of the MSSM neutral Higgs bosons, can be much more gifted. In particular, the rate int

A. A. Barrientos Bendezu, B. A. Kniehl

In this addendum to our paper entitled &#34;W^+- H^-+ Associated Production at the Large Hadron Collider&#34; [Phys. Rev. D 59, 015009 (1999)], we list analytic results for the helicity amplitudes of the partonic subprocess gg -> W^-H^+ induced by virtual quarks.

Holger Gies

We calculate the two-loop effective action of QED for arbitrary constant electromagnetic fields at finite temperature T in the limit of T much smaller than the electron mass. It is shown that in this regime the two-loop contribution always exceeds the influence of the one-loop part due to the thermal excitation of the internal photon. As an application, we s

Nabil Ghodbane

The Monte Carlo program \texttt{SUSYGEN}, initially designed for computing distributions and generating events for supersymmetric particle production in $e^+e^-$ collisions, has now been upgraded to study supersymmetric processes at linear colliders by the inclusion of beamstrahlung, beam polarization, spin correlations and complex couplings including CP vio

Walter Wilcox

By integrating the pressure equation at the surface of a self coupled curvilinear boundary, one may obtain asymptotic estimates of energy shifts, which is especially useful in lattice QCD studies of nonrelativistic bound states. Energy shift expressions are found for periodic (antiperiodic) boundary conditions on antipodal points, which require Neumann (Diri

Alessandro Pelizzola

The cluster variation method (CVM) is an approximation technique which generalizes the mean field approximation and has been widely applied in the last decades, mainly for finding accurate phase diagrams of Ising-like lattice models. Here we discuss in which cases the CVM can yield exact results, considering: (i) one-dimensional systems and strips (in which

S. Aoki, T. Izubuchi, Y. Kuramashi, Y. Taniguchi

We study the quenched lattice QCD using domain-wall fermions at $β=6.0$. Behaviors of both pion mass and the explicit breaking term in the axial Ward-Takahashi identity support the existence of the chiral zero modes. We observe a good agreement between the pion decay constants $f_π$ from both the conserved axial current and the local current perturbatively r

Taku Izubuchi, Kei-ichi Nagai

We investigate the two-dimensional lattice Gross-Neveu model, using the domain-wall fermion formulation, as a toy model of lattice QCD. We study features of the phase diagram related to the mechanism of chiral symmetry restoration, and find that the parity-broken phase (Aoki phase) exists for finite extent in the extra dimension ($N_s$). We also find that O(

B. G. Dimitrov

A model is proposed, according to which the metric tensor field in the standard gravitational Lagrangian is decomposed into a projection (generally - with a non-zero covariant derivative) tensor field, orthogonal to an arbitrary 4-vector field and a tensor part along the same vector field. A theorem has been used, according to which the variation and the par

Owen Dando

We examine the field equations of a self-gravitating texture in low-energy superstring gravity, allowing for an arbitrary coupling of the texture field to the dilaton. Both massive and massless dilatons are considered. For the massless dilaton non-singular spacetimes exist, but only for certain values of the coupling, dependent on the gravitational strength

J. M. Rubí, J. M. G. Vilar

We present some aspects of the rheology of field-responsive suspensions, a class of field-responsive liquid matter systems possessing the ability to undergo significant changes in their strength upon application of an external field. Both the single-particle and the many-particle domains are discussed. In the former, consideration of the full nonlinear dynam

S. H. Pan, E. W. Hudson, K. M. Lang, H. Eisaki

Although their crystal structures are complex, all high temperature superconductors contain some crystal planes consisting of only Cu and O atoms in a square lattice. Superconductivity is believed to originate from strongly interacting electrons in these CuO2 planes. Substitution of a single impurity atom at a Cu site creates a simple but powerful perturbati

M. A. Novotny, P. A. Rikvold, M. Kolesik, D. M. Townsley

We present a brief analysis of the crossover phase diagram for the decay of a metastable phase in a simple dynamic lattice-gas model of a two-phase system. We illustrate the nucleation-theoretical analysis with dynamic Monte Carlo simulations of a kinetic Ising lattice gas on square and cubic lattices. We predict several regimes in which the metastable lifet

Elisa Ercolessi, Giuseppe Morandi, Leonardo Pisani, Marco Roncaglia

We study the competition between non-magnetic (dimer or flux) states and short-range antiferromagnetically ordered RVB states in the t-J model and present a finite temperature phase diagram. We show that, for a wide range of temperatures and dopings, the stable phase results to be a state in which both the flux and the RVB parameters are nonzero.

Sylvain Capponi, Didier Poilblanc, Thierry Giamarchi

The effects of a long range electronic potential on a one dimensional chain of spinless fermions are investigated by numerical techniques (Exact Diagonalisation of rings with up to 30 sites complemented by finite size analysis) and analytic calculations. Due to a competition between the $2 k_F$ oscillations in the density and the (very slow) log divergence o

M. B. Zoelfl, Th. Pruschke, J. Keller, A. I. Poteryaev

The dynamical mean-field theory together with the non-crossing approximation is used to set up a novel scheme to study the electronic structure of strongly correlated electron systems. The non-interacting band structure is obtained from a density functional calculation within the local density approximation. With this method the doped Mott insulator $\rm La_

Mi-Ae Park, Yong-Jihn Kim

Large reductions of the superconducting transition temperature $T_{c}$ and the accompanying loss of the thermal electrical resistivity (electron-phonon interaction) due to radiation damage have been observed for several A15 compounds, Chevrel phase and Ternary superconductors, and $\rm{NbSe_{2}}$ in the high fluence regime. We examine these behaviors based o

P. Millet, F. Mila, F. C. Zhang, M. Mambrini

The magnetic susceptibility of a new one-dimensional, S=1 system, the vanadium oxide LiVGe2O6, has been measured. Contrary to previous S=1 chains, it exhibits an abrupt drop at 22 K typical of a spin-Peierls transition, and it is consistent with a gapless spectrum above this temperature. We propose that this behaviour is due to the presence of a significant

Jean-Pierre Eckmann, Martin Hairer

We study the model of a strongly non-linear chain of particles coupled to two heat baths at different temperatures. Our main result is the existence and uniqueness of a stationary state at all temperatures. This result extends those of Eckmann, Pillet, Rey-Bellet to potentials with essentially arbitrary growth at infinity. This extension is possible by intro

W. Herbst, K. L. Rhode, L. A. Hillenbrand, G. Curran

Eighteen fields in the Orion Nebula Cluster (ONC) have been monitored for one or more observing seasons from 1990-99 with a 0.6-m telescope at Wesleyan University. Photometric data were obtained in Cousins I on 25-40 nights per season. Results from the first 3 years of monitoring were analyzed by Choi & Herbst (1996; CH). Here we provide an update based on 6

Chris Churchill

The properties of Mg II absorption-selected systems show a large variety of kinematics and higher ionization conditions. A multivariate taxonomic study of Mg II absorbers has yielded an &#34;extreme&#34; class of &#34;Double&#34; systems. These Double systems are characterized by kinematic velocity spreads up to 400 km/s, and by twice the Ly alpha, Mg II, Fe

M. L. M. Myrrha, L. P. R. Vaz, M. Faúndez-Abans, M. de Oliveira-Abans

Detailed BVRI-Halpha photometry has been obtained for the ring galaxy HRG 2302. This is probably a still interacting system which shows two principal components: the target, which is a knotted ringed-disk, and the intruder, an elongated galaxy with two substructures probably caused by the interaction. The existence of H II emission regions is suggested by Ha

Robert D. Mathieu, Andrea M. Ghez, Eric L. N. Jensen, Michal Simon

The typical product of the star formation process is a binary star. Binaries have provided the first dynamical measures of the masses of pre-main-sequence (PMS) stars, providing support for the calibrations of PMS evolutionary tracks. Surprisingly, in some star-forming regions PMS binary frequencies are higher than among main-sequence solar-type stars. The d

J. C. Augereau, A. M. Lagrange, D. Mouillet, F. Menard

We report the first resolved scattered light images of the circumstellar dust disk around the old Pre-Main Sequence star HD 141569 A. The disk seen in HST/NICMOS2 images shapes a bright annulus inclined at 37.5 degrees +/- 4.5 degrees from edge-on. This ring peaks at 325+/-10 AU from the star with a characteristic width of ~150 AU. At 1.6 microns, the dust g

Kotaro Kohno, Ryohei Kawabe, Toshihito Shibatsuka, Satoki Matsushita

In order to study the distribution of dense molecular gas and its relation to the central activities (starburst and AGN) in galaxies, we have conducted an imaging survey of HCN(1-0) and HCO+(1-0) emissions from nearby spiral galaxies with the Nobeyama Millimeter Array. In starburst galaxies, we find that there is good spatial coincidence between dense molecu