June 1997 arXiv papers — page 17

Luc Girard, Ermanno F. Borra

Interferometric tests of a f/1.2 2.5-m diameter liquid mirror show RMS surface deviations about wave/20 and Strehl ratios of order 0.6, showing that it is diffraction limited. The mirror is certainly better than implied by the data because of aberrations introduced by the auxiliary testing optics. We have made detailed studies of the scattered light of the m

P. N. Bhat, P. R. Vishwanath, B. S. Acharya, M. R. Krishnaswamy

Very High Energy (VHE) gamma -ray Astronomy observations are planned to be carried out at Pachmarhi in the central Indian state of Madhya Pradesh using the well known atmospheric Cerenkov technique. An array of 25 Cerenkov telescopes is currently under construction. Using this array it is proposed to sample the Cerenkov light pool at various distances from t

P. N. Bhat

In the absence of a standard source of gamma rays or hadrons of known energy one has to study the details of production of \v Cerenkov light at the observation level only through detailed simulation studies. Recently such studies have become all the more important in view of the various techniques resulting from such studies, to distinguish between gamma ray

K. Nomoto, K. Iwamoto, N. Nakasato, F. -K. Thielemann

Among the major uncertainties involved in the Chandrasekhar mass models for Type Ia supernovae are the companion star of the accreting white dwarf (or the accretion rate that determines the carbon ignition density) and the flame speed after ignition. We present nucleosynthesis results from relatively slow deflagration (1.5 - 3 % of the sound speed) to constr

K. Nomoto, M. Hashimoto, T. Tsujimoto, F. -K. Thielemann

Presupernova evolution and explosive nucleosynthesis in massive stars for main-sequence masses from 13 $M_\odot$ to 70 $M_\odot$ are calculated. We examine the dependence of the supernova yields on the stellar mass, $^{12}C(α, γ) ^{16}O}$ rate, and explosion energy. The supernova yields integrated over the initial mass function are compared with the solar ab

S. Seitz, R. P. Saglia, R. Bender, U. Hopp

Using HST WFPC2 V- and R-band data of the z=0.37 cluster MS1512+36 we show that the z=2.72 `protogalaxy' cB58 is not extraordinarily luminous intrinsically but lensed into a gravitational fold arc by the cluster. The arc has a surface brightness weighted axis ratio of 1:7, is marginally resolved in width and about 3 arcsec long. Its counterimage was iden

A. Franceschini, P. Andreani, L. Danese

We exploit observations at 1.25 mm with the ESO-SEST telescope of a southern galaxy sample, selected from the IRAS PSC and complete to $S_{60}=2 Jy$, to derive the FIR and mm luminosity functions and the conditional probability distributions of FIR and mm luminosity of galaxies. The reliability of these estimates is ensured by the good observed correlation o

A. Owens, T. Oosterbroek, A. N. Parmar

We report on observations of the X-ray pulsar 4U 1626-67 by the LECS instrument on-board Bepposax. We confirm the recent ASCA discovery of excess emission near 1 keV (Angelini et al. 1995). The pulse period of 7.66794 +/- 0.00004 s indicates that the source continues to spin-down. The phase averaged spectrum is well fit by an absorbed power-law of photon ind

Leandros Perivolaropoulos

A new statistic is briefly reviewed, designed to detect isolated coherent step-like discontinuities produced by cosmic strings present at late times. As a background I superpose a scale invariant Gaussian random field which could have been produced by a superposition of seeds on all scales and/or by inflationary quantum fluctuations. The statistical variable

Neta A. Bahcall, Xiaohui Fan, Renyue Cen

We show that the evolution of the number density of rich clusters of galaxies breaks the degeneracy between Omega (the mass density ratio of the universe) and sigma_{8} (the normalization of the power spectrum), sigma_{8}Omega^{0.5} \simeq 0.5, that follows from the observed present-day abundance of rich clusters. The evolution of high-mass (Coma-like) clust

Dimitrios Psaltis, Frederick K. Lamb

Compton scattering of photons by nonrelativistic particles is thought to play an important role in forming the radiation spectrum of many astrophysical systems. Here we derive the time-dependent photon kinetic equation that describes spontaneous and induced Compton scattering as well as absorption and emission by static and moving media, the corresponding ra

Sergey Finashin

The Arnold inequalities characterizing the topology of non-singular plane real algebraic curves and the generalization of these inequalities for nodal curves by Viro are extended in this paper for the curves whose singularities have non-degenerated Milnor form. This involves an invariant of such real singularities, the real linking form, which is calculated.

Eanna E. Flanagan

We generalize some results of Ford and Roman constraining the possible behaviors of renormalized expected stress-energy tensors of a free massless scalar field in two dimensional Minkowski spacetime. Ford and Roman showed that the energy density measured by an inertial observer, when averaged with respect to that observers proper time by integrating against

Alexander Shnirman, Gerd Schoen, Ziv Hermon

Low-capacitance Josephson junction arrays in the parameter range where single charges can be controlled are suggested as possible physical realizations of the elements which have been considered in the context of quantum computers. We discuss single and multiple quantum bit systems. The systems are controlled by applied gate voltages, which also allow the ne

Yuri Ozhigov

This work introduces a relative diffusion transformation (RDT) - a simple unitary transformation which acts in a subspace, localized by an oracle. Such a transformation can not be fulfilled on quantum Turing machines with this oracle in polynomial time in general case. It is proved, that every function computable in time T and space S on classical 1-dimensio

A. Chamblin, J. M. A. Ashbourn-Chamblin, R. Emparan, A. Sornborger

It has been argued that a black hole horizon can support the long range fields of a Nielsen-Olesen string, and that one can think of such a vortex as black hole ``hair''. In this paper, we examine the properties of an Abelian Higgs vortex in the presence of a charged black hole as we allow the hole to approach extremality. Using both analytical and numerical

S. Yunoki, J. Hu, A. L. Malvezzi, A. Moreo

The Kondo lattice Hamiltonian with ferromagnetic Hund's coupling as a model for manganites is investigated. The classical limit for the spin of the (localized) $t_{2g}$ electrons is analyzed on lattices of dimension 1,2,3 and $\infty$ using several numerical methods. The phase diagram at low temperature is presented. A regime is identified where phase se

S. A. Ramsey, B. L. Hu

We present a detailed and systematic analysis of the nonperturbative, nonequilibrium dynamics of a quantum field in the reheating phase of inflatonary cosmology, including full back reactions of the quantum field on the curved spacetime, as well as the fluctuations on the mean field. We use the O(N) field theory with unbroken symmetry in a spatially flat FRW

Kay Joerg Wiese

In this article, we perform a careful analysis of the renormalization procedure used in existing calculations to derive critical exponents for the KPZ-equation at 2-loop order. This analysis explains the discrepancies between the results of the different groups. The correct critical exponents in d=2+epsilon dimensions at the crossover between weak- and stron

Oscar Diego

In this paper the large $N$ limit of one hermitian matrix models coupled to an external matrix is considered. It is shown that in the large N limit the number of degrees of freedom are reduced to be order N even though it is order $N^{2}$ for finite N. It is claimed that this result is the origin of the factorization of observables in the path integral forma

Elena Accomando, Alessandro Ballestrero, Marco Pizzio

We compute several total and differential cross sections relevant to top and WWZ physics at future $e^+e^-$ colliders taking into account the full set of Feynman diagrams for six fermion final states. We also include in our calculations initial state radiation and beamstrahlung effects, and the most important QCD corrections in an approximate (naive) form. W

A. W. Strong, I. V. Moskalenko, V. Schoenfelder

An extensive program for the calculation of galactic cosmic-ray propagation has been developed. Primary and secondary nucleons, primary and secondary electrons, and secondary positrons are included. The basic spatial propagation mechanisms are (momentum-dependent) diffusion, convection, while in momentum space energy loss and diffusive reacceleration are tre

Ken'ichi Nomoto, Koichi Iwamoto, Nobuhiro Kishimoto

Spectroscopic and photometric evidence indicates that Type Ia supernovae (SNe Ia) are the thermonuclear explosions of accreting white dwarfs. However, the progenitor binary systems and hydrodynamical models for SNe Ia are still controversial. The relatively uniform light curves and spectral evolution of SNe Ia have led to their use as a standard candle for d

UKQCD Collaboration, T. Manke, I. T. Drummond, R. R. Horgan

We explore the effect of higher order operators in the non-relativistic formulation of QCD (NRQCD). We calculated masses in the b \bar b spectrum using quenched gauge configurations at beta = 6.0 and two different NRQCD actions which have been corrected to order mv^4 and mv^6. The two-point functions are calculated in a gauge invariant fashion. We find the g

Hideo Fusaoka, Yoshio Koide

The running quark masses at various energy scales are evaluated by using the mass renormalization equations systematically. Also, those at energy scales higher than m_Z are evaluated by using the evolution equations of Yukawa coupling constants for the standard model with a single Higgs boson.

David A. Kosower

I present a highly efficient method for evolving parton distributions in perturbative QCD. The method allows evolving the parton distribution functions according to any of the commonly-used truncations of the evolution equations (which differ in their treatment of higher-order terms). I also give formulæ for computing crossing functions within the method.

Tetsu Iwama, Akihisa Kohama, Koichi Yazaki

We examine the nuclear transparency for the quasi-elastic ($e, e'p$) process at large momentum transfers in a relativistic quantum-mechanical model for the internal structure of the proton, using a relativistic harmonic oscillator model. A proton in a nuclear target is struck by the incident electron and then propagates through the residual nucleus suffe

Shin'ichi Nojiri, S. D. Odintsov

Using the results of the calculation of the one-loop effective action (E. Elizalde et al , Phys.Rev. D49 (1994) 2852), we find the trace anomaly for most general conformally invariant 2D dilaton coupled scalar-dilaton system (the contribution of dilaton itself is included). The non-local effective action induced by conformal anomaly for such system is found.

Roberto Onofrio, Lorenza Viola

Free fall experiments are discussed by using test masses associated to quantum states not necessarily possessing a classical counterpart. The times of flight of the Galileian experiments using classical test masses are replaced in the quantum case by probability distributions which, although still not defined in an uncontroversial manner, become manifestly d

C. Quesne

We define some new algebraic structures, termed coloured Hopf algebras, by combining the coalgebra structures and antipodes of a standard Hopf algebra set $\cal H$, corresponding to some parameter set $\cal Q$, with the transformations of an algebra isomorphism group $\cal G$, herein called colour group. Such transformations are labelled by some colour param

Jarmo Hietarinta, Frank Nijhoff

In this paper we derive from arguments of string scattering a set of eight tetrahedron equations, with different index orderings. It is argued that this system of equations is the proper system that represents integrable structures in three dimensions generalising the Yang-Baxter equation. Under additional restrictions this system reduces to the usual tetrah

A. Taormina, S. M. J. Wilson

Some identities between unitary minimal Virasoro characters at levels 3, 4 and 5 are shown to arise as a consequence of relations between Artin L-functions of different quadratic fields. The definitions and concepts of number theory necessary to present the theta function identities which can be derived from these relations are introduced. A new infinite fam

R. Rapp, R. Machleidt, J. W. Durso, G. E. Brown

We show that the assumption of dropping meson masses together with conventional many-body effects, implemented in the relativistic Dirac-Brueckner formalism, explains nuclear saturation. We use a microscopic model for correlated $2π$ exchange and include the standard many-body effects on the in-medium pion propagation, which initially increase the attractive

Sergei G. Matinyan

This paper reviews the application of optical and UV laser radiation to several topics in low-energy nuclear physics. We consider the laser-induced nuclear anti-Stokes transitions, the laser-assisted and the laser-induced internal conversion, and the Electron Bridge and Inverse Electron Bridge mechanisms as tools for deexciting and exciting of low-lying nucl

V. S. Uma Maheswari, C. Fuchs, Amand Faessler, L. Sehn

The properties of the high energy pions observed in heavy ion collisions, in particular in the system Au on Au at 1 GeV/nucleon are investigated. The reaction dynamics is described within the Quantum Molecular Dynamics (QMD) approach. It is shown that high energy pions freeze out early and originate from the hot, compressed matter. $N^*$--resonances are foun

R. A. Arndt, C. H. Oh, I. I. Strakovsky, R. L. Workman

A partial-wave analysis of NN elastic scattering data has been completed. This analysis covers an expanded energy range, from threshold to a laboratory kinetic energy of 2.5 GeV, in order to include recent elastic pp scattering data from the EDDA collaboration. The results of both single-energy and energy-dependent analyses are described.

Klaus Geiger, Dinesh Kumar Srivastava

We examine Pb+Pb collisions at CERN SPS energy 158 A GeV, by employing the earlier developed and recently refined parton-cascade/cluster-hadronization model and its Monte Carlo implementation. This space-time model involves the dynamical interplay of perturbative QCD parton production and evolution, with non-perturbative parton-cluster formation and hadron p

Munshi Golam Mustafa, Dipali Pal, Dinesh Kumar Srivastava

We study the propagation of charm quarks, produced from the initial fusion of partons, in an equilibrating quark-gluon plasma which may be formed in the wake of relativistic collisions of gold nuclei. Initial conditions are taken from a self screened parton cascade model and the chemical equilibration is assumed to proceed via gluon multiplication and quark

George Marinescu

We prove extension results for meromorphic functions by combining the Kohn-Rossi extension theorems with Andreotti's theory on the algebraic and analytic dependence of meromorphic functions on pseudoconcave manifolds. Versions of Kohn-Rossi theorems for pseudoconvex domains are included.

Moulay Youssef Barkatou

In this paper a new explicit integral formula is derived for solutions of the tangential Cauchy-Riemann equations on CR q-concave manifolds and optimal estimates in the Lipschitz norms are obtained.

Lorenzo Cornalba, Frank Wilczek

The long-range fields associated with non-abelian vortices generally obstruct full realization, in the spectrum, of the symmetry of the ground state. In the context of 2+1 dimensional field theories, we show how this effect manifests itself concretely in altered conditions for the angular momentum and in the energy spectrum. A particularly interesting case i

A. De Giovanni, M. T. Grisaru, M. Rocek, R. von Unge

We have carried out a two loop computation of the low-energy effective action for the four-dimensional N=2 supersymmetric Yang-Mills system coupled to hypermultiplets, with the chiral superfields of the vector multiplet lying in an abelian subalgebra. We have found a complete cancellation at the level of the integrands of Feynman amplitudes, and therefore th

Gerald Dunne, Joshua Feinberg

We discuss supersymmetric quantum mechanical models with periodic potentials. The important new feature is that it is possible for both isospectral potentials to support zero modes, in contrast to the standard nonperiodic case where either one or neither (but not both) of the isospectral pair has a zero mode. Thus it is possible to have supersymmetry unbroke

Hongsu Kim

Superradiant scattering, which can be thought of as the wave analogue of the Penrose process is revisited. As is well-known, boson fields display superradiance provided they have frequency in a certain range whereas fermion fields do not. A succinct superradiance-checking algorithm employing particle number or energy current is formally reviewed and then app

Hongsu Kim

By applying Newman's method, the AdS_3 rotating black hole solution is "derived" from the nonrotating black hole solution of Banados, Teitelboim and Zanelli (BTZ). The rotating BTZ solution derived in this fashion is given in "Boyer-Lindquist-type" coordinates whereas the form of the solution originally given by BTZ is given in a kind of

J. Sucher

The concept of the potential acting between charged particles is reviewed within the framework of quantum electrodynamics. The one-photon and two-photon exchange potentials V_1 γand V_2 γare discussed, with attention to the following features: the dependence of V_2 γon the choice of V_1 γ, the distinction between FGI (Feynman gauge inspired) and CGI (Coulomb

W. Hollik, W. M. Moesle, D. Wackeroth

The cross section of top pair production in hadronic collisions to O(alpha α_s^2) is calculated within the General 2-Higgs-Doublet Model and the Minimal Supersymmetric Standard Model. At the parton level the O(alpha) one-loop corrections to the main production mechanisms, quark-antiquark annihilation and gluon fusion, significantly modify the Born-cross sect

H. F. Jones, A. Ritz, I. L. Solovtsov

We analyze inclusive $τ$ decay using a modified version of the $a$ expansion, a non-perturbative technique in which the effective coupling is analytic in the infrared region. The modification involves renormalization group improvement of the integrand in a spectral representation for the D-function prior to implementing the $a$ expansion. The advantage of th

O. Bertolami, D. Colladay, V. A. Kostelecký, R. Potting

In the context of string field theory, the possibility exists for the spontaneous violation of Lorentz invariance and CPT. In this talk, we review its status and some experimental constraints. We discuss the possibility that stringy CPT violation could give rise to a mechanism in which baryogenesis occurs in the early Universe in thermal equilibrium and show

K. D. Anderson, D. A. Ross, M. G. Sotiropoulos

D.I.S. at small Bjorken $x$ is considered within the dipole cascade formalism. The running coupling in impact parameter space is introduced in order to parametrize effects that arise from emission of large size dipoles. This results in a new evolution equation for the dipole cascade. Strong coupling effects are analyzed after transforming the evolution equat

Dongsheng Du, Li-bo Guo, Da-Xin Zhang

Using the PQCD method we calculate the W-exchange and the W-annihilation processes of B mesons, which in general involve a charm quark or anti-quark in the final state. The nonvanishing amplitudes of these processes are found to be suppressed by a factor of $m_c/m_b$ compared to the tree or the time-like penguin processes, but some of them are within the rea

C. D. Froggatt, M. Gibson, H. B. Nielsen, D. J. Smith

The fermion masses and mixing angles are fitted using only 3 free parameters in a non-supersymmetric extension of the Standard Model, with new approximately conserved chiral gauge quantum numbers broken by a set of Higgs fields. The fundamental mass scale of this anti-grand unification model is given by the Planck mass. We also calculate neutrino mixing angl

W. T. Giele, E. W. N. Glover, D. A. Kosower

We define the radial moment, <r>, for jets produced in hadron-hadron collisions. It can be used as a tool for studying, as a function of the jet transverse energy and pseudorapidity, radiation within the jet and the quality of a perturbative description of the jet shape. We also discuss how non-perturbative corrections to the jet transverse energy affect <r>

G. Burgio, F. Di Renzo, G. Marchesini, E. Onofri

We present some evidence that in Lattice Gauge Theory the condensate contains a non-perturbative contribution proportional to $Λ^2$, the square of the physical scale. This result is based on an analysis of the Wilson loop plaquette expectation from Monte Carlo simulations and its perturbative expansion computed to eight loops. The analysis is not fully concl

Peter Hasenfratz, Ferenc Niedermayer

It has been pointed out in recent papers that the example considered earlier in the O(N) sigma-model to test whether fixed-point actions are 1-loop perfect actually checked classical perfection only. To clarify the issue we constructed the renormalized trajectory explicitly in 1-loop perturbation theory. We found that the fixed-point action is not exactly 1-

C. Adloff

Deep inelastic e^+ scattering data, taken with the H1 detector at HERA, are used to study the event shape variables thrust, jet broadening and jet mass in the current hemisphere of the Breit frame over a large range of momentum transfers Q between 7 GeV and 100 GeV. The data are compared with results from e^+e^- experiments. Using second order QCD calculatio

David Gerdes

Recent measurements of the top quark production cross section and decay properties by the CDF and D0 experiments are described. The cross section has been measured in dilepton, lepton plus jets, and all-hadronic final states, and a measurement of $BR(t \to Wb)/BR(t \to Wq)$, where $q$ is any quark, has been performed. The results, though statistics-limited,

R. Casadio, B. Harms, Y. Leblanc

The Bekenstein-Hawking ``entropy&#39;&#39; of a Kerr-Newman dilaton black hole is computed in a perturbative expansion in the charge-to-mass ratio. The most probable configuration for a gas of such black holes is analyzed in the microcanonical formalism and it is argued that it does not satisfy the equipartition principle but a bootstrap condition. It is als

Hongsu Kim

An attempt is made to supplement Carter&#39;s partial investigation of the global structure of Kerr-Newman spacetime on the symmetry axis. Namely, the global structure of θ= const. timelike submanifolds of Kerr-Newman metric starting from the symmetry axis all the way down to the equatorial plane are studied by introducing a new time coordinate slightly diff

S. A. Ramsey, B. L. Hu

For the O(N) field theory with lambda Phi^4 self-coupling, we construct the two-particle-irreducible (2PI), closed-time-path (CTP) effective action in a general curved spacetime. From this we derive a set of coupled equations for the mean field and the variance. They are useful for studying the nonperturbative, nonequilibrium dynamics of a quantum field when

Renato Vicente, Nestor Caticha

We study the online dynamics of learning in fully connected soft committee machines in the student-teacher scenario. The locally optimal modulation function, which determines the learning algorithm, is obtained from a variational argument in such a manner as to maximise the average generalisation error decay per example. Simulations results for the resulting

Augusto Gonzalez, Ricardo Perez, Pavel Fileviez

We consider systems of two and three electrons in a two-dimensional parabolic quantum dot. A magnetic field is applied perpendicularly to the electron plane of motion. We show that the energy levels corresponding to states with high angular momentum, J, and a low number of vibrational quanta may be systematically computed as power series in 1/|J|. These stat

J. J. Deisz, D. W. Hess, J. W. Serene

We report on a fully self-consistent determination of a phase transition to a superconducting state in a conserving approximation. The transition temperature calculated for a two-dimensional Hubbard model with an attractive interaction in the fluctuation exchange approximation agrees with quantum Monte Carlo calculations. The temperature dependences of the s

Daniel M. Zuckerman, Michael E. Fisher, Benjamin P. Lee

Approximate theories for the restricted primitive model electrolyte are compared in the light of Totsuji&#39;s lower bound for the energy (an improvement over Onsager&#39;s), Gillan&#39;s upper bound for the free energy, and thermal stability requirements. Theories based on the Debye-Hueckel (DH) approach and the mean spherical approximation (MSA), including

G. Visentini, A. Painelli, A. Girlando, A. Fortunelli

We prove that the upper electronic bands of k-phase BEDT-TTF salts are adequately modeled by an half-filled tight-binding lattice with one site per cell. The band parameters are derived from recent ab-initio calculations, getting a very simple but extremely accurate one-electron picture. This picture allows us to solve the BCS gap equation adopting a real-sp

Jari M. Kinaret, Mats Jonson, Robert I. Shekhter, Sebastian Eggert

We consider a ring of strongly interacting electrons connected to two external leads by tunnel junctions. By studying the positions of conductance resonances as a function of gate voltage and magnetic flux the interaction parameter $g$ can be determined experimentally. For a finite ring the minimum conductance is strongly influenced by device geometry and el

M. Potthoff, W. Nolting

The Hubbard model on a semi-infinite three-dimensional lattice is considered to investigate electron-correlation effects at single-crystal surfaces. The standard second-order perturbation theory in the interaction U is used to calculate the electronic self-energy and the quasi-particle density of states (QDOS) in the bulk as well as in the vicinity of the su

A. S. Moskvin, V. A. Korotaev, Yu. D. Panov, M. A. Sidorov

The Hartree-Fock states of the many-electron atomic system can be unstable with respect to a static or dynamic shift of the electron shells. An appropriate non-rigid shell model for atomic clusters is developed. It permits to formulate a convenient approach to the semiempirical description of the different correlation effects and to reveal some new effects.

P. Garbaczewski

We establish circumstances under which the dispersion of passive contaminants in a forced, deterministic or random, flow can be consistently interpreted as a Markovian diffusion process. In case of conservative forcing the repulsive case only, $\vec{F}=\vec{\nabla }V$ with $V(\vec{x},t)$ bounded from below, is unquestionably admitted by the compatibility con

Claudia S. Rola, Elena Terlevich, Roberto J. Terlevich

We present new quantitative classification methods for emission-line galaxies, which are specially designed to be used in deep galaxy redshift surveys. A good segregation between starbursts and active galactic nuclei, i.e. Seyferts 2s and LINERs, is obtained from diagnostic diagrams involving the [O II]λ3727 Å, [Ne III]\lambda3869 Å, Hβand [O III]\lambda5007

R. A. Battye

The physics of photon diffusion for the case of active sources is very different to that of passive sources. Fluctuations created just before the time of last scattering allow anisotropy to be created on scales much smaller than allowed by standard Silk d amping. We develop a formalism to treat this effect and investigate its consequences using simple exampl

R. A. Battye, E. P. S. Shellard

We review current cosmological constraints on the axion. We describe the basic mechanisms by which axions are created in the early universe, focussing on the standard thermal scenario where the dominant process is through axion radiation by a string network. A dark matter axion in this case would have a mass $\ma \sim 100 \microeV$, with specified large unce

R. A. Battye, R. R. Caldwell, E. P. S. Shellard

Gravitational waves from cosmic strings are generated in the first fractions of a second after the Big Bang, potentially providing a unprecedented probe of the early universe. We discuss the key dynamical processes underlying calculations of the stochasti c background produced by a string network and we detail the parameter dependencies of the resulting spec

D. Palle

We show that in the Einstein-Cartan gravity it is possible to obtain a relation between Hubble&#39;s expansion and the global rotation (vorticity) of the Universe. Gravitational coupling can be reduced to dimensionless quantity of order unity, fixing the scalar mass density and the resulting negative cosmological constant at spacelike infinity. Current estim

G. B. Taylor, R. C. Vermeulen

We present measurements of bi-directional motions in the jets of the radio galaxy 1946+708 at z=0.101. This is a Compact Symmetric Object with striking S-symmetry. Sensitive 15 GHz observations reveal a compact component at the center of symmetry with a strongly inverted spectrum, that we identify as the core. From five 4.9 GHz observations spread over 4 yea

E. Kuulkers, A. N. Parmar, A. Owens, T. Oosterbroek

We present a 0.2-10 keV spectrum of the low-mass X-ray binary Cygnus X-2 obtained using the Low Energy Concentrator Spectrometer on-board Bepposax. The spectrum can be described by a cut-off power-law model with absorption of (2.28 +/- 0.07) 10^{21} atoms/cm^2, a power-law index of 0.78 +/- 0.02 and a cut-off energy of 4.30 +/- 0.08 keV (68% confidence error

A. N. Parmar, P. Kahabka, H. W. Hartmann, J. Heise

We report on a BeppoSAX Concentrator Spectrometer observation of the super-soft source (SSS) CAL87. The X-ray emission in SSS is believed to arise from nuclear burning of accreted material on the surface of a white dwarf (WD). An absorbed blackbody spectral model gives a chi^2_v of 1.18 and a temperature of 42 +/- ^13 _11 eV. However, the derived luminosity

C. Codella, R. Welser, C. Henkel, P. J. Benson

Trying to obtain a more complete picture of star forming regions in the Taurus Molecular Cloud, four newly discovered dense cores (L1521D, L1521F, L1524, L1507A) are identified and mapped through the ammonia (J,K)=(1,1) and (2,2) rotational inversion lines. These cores have sizes of 0.06-0.09 pc, hydrogen densities of order 10000 - 100000 cm-3 and kinetic te

Martin Lopez Corredoira

This article presents a statistical-mechanical treatment of a relationship (the force equation) between the gravitational potential for two particles and the correlation functions in a relaxed distribution of particles with different masses. This relationship is used in the case of galaxies interacting through a Newtonian potential in an Universe in expansio

Cristina C. Popescu, Ulrich Hopp, Hans Elsässer

We present the results of a search for emission-line galaxies (ELGs) towards nearby voids, based on a sample selected on the HQS (Hamburg Quasar Survey) - III-aJ objective-prism plates. The survey was based on the presence of emission-lines and therefore has the advantage to detect very faint objects (with all the flux in the emission-lines and almost no con

O. K. Sil&#39;chenko, V. V. Vlasyuk, A. N. Burenkov

The Sb galaxy NGC 2841 was observed at the 6 m telescope of SAO RAS with the Multi-Pupil Field Spectrograph and at the 1 m telescope of SAO RAS with the long-slit spectrograph. An unresolved nucleus of NGC 2841 is shown to be chemically decoupled both in magnesium and in iron with abundance break estimates of 0.36 dex for Mg and 0.6 dex for Fe; an abundance

Sandip K. Chakrabarti, Soumitri A. Sahu

We revisit Bondi flows on black holes, naked singularities and neutron stars keeping in mind recent progress in understanding of the flow behaviour near compact objects. In an adiabatic spherical accretion on black holes and naked singularities, standing shock waves do not form, but shocks on neutron stars may or may not form depending on the boundary condit

Girish S. Setlur, Yia-Chung Chang

Based on a class of exactly solvable models of interacting bose and fermi liquids, we compute the single-particle propagators of these systems exactly for all wavelengths and energies and in any number of spatial dimensions. The field operators are expressed in terms of bose fields that correspond to displacements of the condensate in the bose case and displ

Eugene Perevalov, Govindan Rajesh

We consider F-theory compactifications on a mirror pair of elliptic Calabi-Yau threefolds. This yields two different six-dimensional theories, each of them being nonperturbatively equivalent to some compactification of heterotic strings on a K3 surface S with certain bundle data E --> S. We find evidence for a transformation of S together with the bundle tha

Shoichi Sasaki, Osamu Miyamura

We study $U_A$(1) anomaly of non-perturbative QCD in the maximally abelian gauge on SU(2) lattice. The existence of the strong correlation between QCD-monopoles and instantons in the abelian gauge is shown by both analytic and numerical works including lattice simulations. These results bring us a conjecture that the $U_A$(1) symmetry would be explicitly bro

Daniel I. Fivel

The spin state of two magnetically inequivalent protons in contiguous atoms of a molecule becomes entangeled by the indirect spin-spin interaction (j-coupling). The degree of entanglement oscillates at the beat frequency resulting from the splitting of a degeneracy. This beating is manifest in NMR spectroscopy as an envelope of the transverse magnetization a

Anatoly Konechny, Albert Schwarz

We define a finite-dimensional partially formal supermanifold as a manifold having $q$ odd coordinates and $k + l$ even coordinates with $l$ of them taking only nilpotent values. We show that this notion can be used to formulate superconformal field theories with different numbers of supersymmetries in holomorphic and antiholomorphic sectors.

N. Dorey, V. V. Khoze, M. P. Mattis, M. J. Slater

We discuss the contribution of ADHM multi-instantons to the higher-derivative terms in the gradient expansion along the Coulomb branch of N=2 and N=4 supersymmetric SU(2) gauge theories. In particular, using simple scaling arguments, we confirm the Dine-Seiberg nonperturbative nonrenormalization theorems for the 4-derivative/8-fermion term in the two finite

Hongsu Kim

The conformal structure of Brans-Dicke gravity action is carefully studied. It is discussed that Brans-Dicke gravity action has definitely no conformal invariance. It is shown, however, that this lack of conformal invariance enables us to demonstrate that Brans-Dicke theory appears to have a better short-distance behavior than Einstein gravity as far as Eucl

Edmond L. Berger, Harry Contopanagos

We discuss calculations of the inclusive total cross section for heavy quark production at hadron collider energies within the context of perturbative quantum chromodynamics, including resummation of the effects of initial-state soft gluon radiation to all orders in the strong coupling strength. We resum the universal leading-logarithm contributions, and we

J. Blümlein, N. Kochelev

We discuss the relations between the twist 2 and twist 3 contributions to polarized deep-inelastic scattering structure functions both for neutral and charged current interactions which are predicted by the operator product expansion in lowest order in QCD.

Rafael D. Sorkin

In seeking to arrive at a theory of ``quantum gravity&#39;&#39;, one faces several choices among alternative approaches. I list some of these ``forks in the road&#39;&#39; and offer reasons for taking one alternative over the other. In particular, I advocate the following: the sum-over-histories framework for quantum dynamics over the ``observable and state-

Jean-Claude Hausmann, Allen Knutson

We compute the integer cohomology rings of the ``polygon spaces&#39;&#39; introduced in [Hausmann,Klyachko,Kapovich-Millson]. This is done by embedding them in certain toric varieties; the restriction map on cohomology is surjective and we calculate its kernel using ideas from the theory of Gröbner bases. Since we do not invert the prime 2, we can tensor wit

Johannes Huebschmann

A Chern-Weil construction for extensions of Lie-Rinehart algebras is introduced. This generalizes the classical Chern-Weil construction in differential geometry and yields characteristic classes for arbitrary extensions of Lie-Rinehart algebras. Some examples arising from spaces with singularities and from foliations are given that cannot be treated by means

P. Jonsson, T. Drakengren

We investigate the computational properties of the spatial algebra RCC-5 which is a restricted version of the RCC framework for spatial reasoning. The satisfiability problem for RCC-5 is known to be NP-complete but not much is known about its approximately four billion subclasses. We provide a complete classification of satisfiability for all these subclasse

M. E. Pollack, D. Joslin, M. Paolucci

Several recent studies have compared the relative efficiency of alternative flaw selection strategies for partial-order causal link (POCL) planning. We review this literature, and present new experimental results that generalize the earlier work and explain some of the discrepancies in it. In particular, we describe the Least-Cost Flaw Repair (LCFR) strategy

K. Yaman, M. Jeng, P. Pincus, C. Jeppesen

We consider an ideal gas of infinitely rigid rods near a perfectly repulsive wall, and show that the interfacial tension of a surface with rods on one side is lower when the surface bends towards the rods. Surprisingly we find that rods on both sides of surfaces also lower the energy when the surface bends. We compute the partition functions of rods confined

Yu. M. Bunkov, O. D. Timofeevskaya

At a very rapid superfluid transition in $^3$He, follows after a reaction with single neutron, the creation of topological defects (vortices) has recently been demonstrated in accordance with the Kibble-Zurek scenario for the cosmological analogue. We discuss here the extension of the Kibble-Zurek scenario to the case when alternative symmetries may be broke

Martin Fliesser, András Csordás, Péter Szépfalusy, Robert Graham

The collective excitations of Bose condensates in anisotropic axially symmetric harmonic traps are investigated in the hydrodynamic and Thomas-Fermi limit. We identify an additional conserved quantity, besides the axial angular momentum and the total energy, and separate the wave equation in elliptic coordinates. The solution is reduced to the algebraic prob

Sandip K. Chakrabarti

Close to a black hole, the density of the sub-Keplerian accreting matter becomes higher compared to a spherical flow due to the presence of a centrifugal barrier independent of whether or not a standing shock actually forms. This hot dense flow intercepts soft photons from a cold Keplerian disk and reprocesses them to form high energy X-rays and gamma rays.