August 1996 arXiv papers — page 9

M. Lublinsky

The transition constant for the hadronic decay $ω\rightarrow ρπ$ is investigated by means of QCD sum rules in external axial field. The obtained value for $g_{ωρπ}$ is about 16 GeV${}^{-1}$ that is in a good agreement with experimental data.

Lesley L. Smith, Pankaj Jain, Douglas W. McKay

We investigate the contribution of technicolor mechanisms to the production of single top quarks at hadron colliders. We find that a promising candidate process is gluon-gluon fusion to produce a W-boson plus technipion, with subsequent decay of the technipion to a top quark plus a bottom quark. The top-plus-bottom mode is the dominant one when the technipio

Weonjong Lee, Markus Klomfass

We have computed $ B_K $ with staggered fermions, using two different methods: both in the one spin trace form and two spin trace form. Renormalized results in both forms are in good agreement. The numerical simulations were performed on a $ 16^3 \times 40 $ lattice in full QCD with $ β= 5.7 $. We also tried an improved wall source method in order to select

C. Bernard, T. Blum, T. DeGrand, C. E. DeTar

As part of a larger project to estimate the fB decay constant, we are recalculating fB_static using a variational smearing method in an effort to improve accuracy. Preliminary results for the static B_B parameter and HQET two point functions are also presented.

F. Karsch, T. Neuhaus, A. Patkós, J. Rank

We study the effective 3-D SU(2) Gauge-Higgs model at finite temperature for Higgs-masses in the range from $60$ GeV up to $100$ GeV. The first order electroweak phase transition weakens with increasing Higgs-mass and terminates at a critical end-point. For Higgs-mass values larger than about $m_{H,c}=75.4(6)$ GeV the thermodynamic signature of the transitio

R. C. Brower, T. L. Ivanenko, J. W. Negele, K. N. Orginos

In order to optimize cooling as a technique to study the instanton content of the QCD vacuum, we have studied the effects of alternative algorithms, improved actions and boundary conditions on the evolution of single instantons and instanton anti-instanton pairs. Using these results, we have extracted and compared the instanton content of quenched and full Q

SESAM-Collaboration, U. Glaessner, S. Guesken, H. Hoeber

We present results from an analysis of the light spectrum and the decay constants f_π and f_V^{-1} in Full QCD with n_f=2 Wilson fermions at a coupling of beta=5.6 on a 16^3x32 lattice.

Jan Smit

We review some of the phenomenology in 4D dynamical triangulation and explore its interpretation in terms of a euclidean effective action of the continuum form $\intx \sqrt{g} [μ-\frac{1}{16πG} R + \cdots]$.

M. Göckeler, R. Horsley, M. Ilgenfritz, H. Oelrich

We present initial results for light hadron masses and nucleon structure functions using a recent proposal for eliminating all $O(a)$ effects from Wilson fermion simulations in the quenched approximation. With initially limited statistics, we find a much more linear APE plot and a value of the axial coupling $g_A$ nearer to the experimental point than with c

Joe Kiskis

This paper shows that there are no physical walls in the deconfined, high-temperature phase of Z(2) lattice gauge theory. In a Hamiltonian formulation, the interface in the Wilson lines is not physical. The line interface and its energy are interpreted in terms of physical variables. They are associated with a difference between two partition functions. One

Brett E. Taylor, William A. Hiscock, Paul R. Anderson

Static traversable wormhole solutions of the Einstein equations require ``exotic'' matter which violates the weak energy condition. The vacuum stress-energy of quantized fields has been proposed as the source for this matter. Using the Dewitt-Schwinger approximation, analytic expressions for the stress-energy of a quantized massive scalar field are c

Mark Israelit

Dark matter is obtained from a scalar field coupled conformally to gravitation; the scalar being a relict of Dirac's gauge function. This conformally coupled dark matter includes a gas of very light ($m\approx 2.25\times 10^{-34} eV$) neutral bosons having spin 0, as well as a time-dependent global scalar field, both pervading all of the cosmic space. Th

T. V. Shahbazyan, M. E. Raikh

We extend Wegner's exact solution for the 2D density of states at the lowest Landau level with a short--range disorder to the cases of a double--layer system and a superlattice. For the double--layer system, an analytical expression for the density of states, illustrating the interplay between the tunnel splitting of Landau levels and the disorder--induc

Y. Alhassid, H. Attias

We show that the parametric correlations of the conductance peak amplitudes of a chaotic or weakly disordered quantum dot in the Coulomb blockade regime become universal upon an appropriate scaling of the parameter. We compute the universal forms of this correlator for both cases of conserved and broken time reversal symmetry. For a symmetric dot the correla

Joshua Wilkie, Paul Brumer

We prove quantum-classical correspondence for bound conservative classically chaotic Hamiltonian systems. In particular, quantum Liouville spectral projection operators and spectral densities, and hence classical dynamics, are shown to approach their classical analogs in the $h\rightarrow 0$ limit. Correspondence is shown to occur via the elimination of esse

Joshua Wilkie, Paul Brumer

A general program to show quantum-classical correspondence for bound conservative integrable and chaotic systems is described. The method is applied to integrable systems and the nature of the approach to the classical limit, the cancellation of essential singularities, is demonstrated. The application to chaotic systems requires an understanding of classica

Predrag Cvitanovic, Gabor Vattay, Andreas Wirzba

A "quasiclassical" approximation to the quantum spectrum of the Schroedinger equation is obtained from the trace of a quasiclassical evolution operator for the "hydrodynamical" version of the theory, in which the dynamical evolution takes place in the extended phase space $[q(t),p(t),M(t)] = [q_i, \partial_i S, \partial_i \partial_j S ]$. The

Alexander Kusenko, Gino Segre

We have recently proposed an explanation for the birth velocities of pulsars as resulting from asymmetries due to neutrino oscillations in the cooling protoneutron star. A specific prediction of this mechanism is that the correlation of velocities and magnetic fields should be stronger for slowly rotating neutron stars and weaker for those whose periods are

Kurt Roettiger, Jack O. Burns, Chris Loken

We present an observational analysis of numerical simulations of galaxy cluster mergers. We identify several observational signatures of recent merger activity, and quantitatively assess the uncertainty introduced into cluster mass estimates when invoking the commonly held assumptions of hydrostatic equilibrium, virial equilibrium, spherical symmetry and iso

A. J. Stirling, J. A. Peacock

We probe the statistical nature of the primordial density field by measuring correlations between the power in adjacent Fourier modes. For certain types of non-Gaussian field, these k-space correlations would be expected to be more extended than for a Gaussian field, providing a useful discriminatory test for Gaussian fields. We apply this test to the combin

V. P. Reshetnikov, V. A. Hagen-Thorn, V. A. Yakovleva

We present the results of detailed surface photometry of NGC 3808B and NGC 6286 - two spiral galaxies with possibly forming ring-like structures rotating around major axes of the galaxies. The formation of rings in NGC 3808B and NGC 6286 being accompanied by accretion of matter on galactic disk results in some interesting gasdynamical and stellardynamical ef

Diego Harari, Justin Hayward, Matias Zaldarriaga

We estimate the depolarizing effect of a primordial magnetic field upon the cosmic microwave background radiation due to differential Faraday rotation across the last scattering surface. The degree of linear polarization of the CMB is significantly reduced at frequencies around and below 30 GHz $(B_* /10^{-2}{\rm Gauss})^{1/2}$, where $B_*$ is the value of t

Takeshi Fukuyama, Mikiko Hatakeyama, Masae Miyoshi, Masahiro Morikawa

We explore the cosmological model in which a late-time mild inflation is realized after the star formation epoch. Non-vanishing curvature coupling of a classical boson field yields this mild inflation without a cosmological constant. Accordingly the lifetime of the present Universe is remarkably increased in our model. Thus we show that the present observed

Kan Chen

We propose a learning algorithm for solving the traveling salesman problem based on a simple strategy of trial and adaptation: i) A tour is selected by choosing cities probabilistically according to the ``synaptic'' strengths between cities. ii) The ``synaptic'' strengths of the links that form the tour are then enhanced (reduced) if the tour

W. Hollik

In this talk the Higgs boson effects in electroweak precision observables are reviewed and the possibility of indirect information on the Higgs mass from electroweak radiative corrections and precision data is discussed.

Sebastian E. Larsson, Subir Sarkar, Peter L. White

Discrete symmetries are commonplace in field theoretical models but pose a severe problem for cosmology since they lead to the formation of domain walls during spontaneous symmetry breaking in the early universe. However if one of the vacuua is favoured over the others, either energetically, or because of initial conditions, it will eventually come to domina

G. M. Bruun, V. N. Nicopoulos, N. F. Johnson

We investigate de Haas-van Alphen (dHvA) oscillations in the mixed state of a type-II two-dimensional superconductor within a self-consistent Gor'kov perturbation scheme. Assuming that the order parameter forms a vortex lattice we can calculate the expansion coefficients exactly to any order. We have tested the results of the perturbation theory to fourt

B. Schroer

It has been known that the Wigner representation theory for positive energy orbits permits a useful localization concept in terms of certain lattices of real subspaces of the complex Hilbert -space. This ''modular localization'' is not only useful in order to construct interaction-free nets of local algebras without using non-unique '&#39

G. K. Leontaris, N. D. Tracas

Motivated from unified models with string origin, we analyse the constraints from duality invariance on effective supergravity models with an intermediate gauge symmetry. Requiring vanishing vacuum energy and invariance of the superpotential couplings, we find that modular weights of the matter and higgs fields are subject to various constraints. In addition

R. S. Chivukula, E. H. Simmons

The triviality of the scalar sector of the standard one-doublet Higgs model implies that it is only an effective low-energy theory valid below some cut-off scale $Λ$. In this note we show that the experimental constraint on the amount of custodial symmetry violation, $|Δρ_* | = α|T | \le 0.4\%$, implies that the scale $Λ$ must be greater than of order 7.5 Te

A. Cobis, A. S. Jensen, D. V. Fedorov

The recently developed method to solve the Faddeev equations in coordinate space is used to study the weakly bound halo nucleus, the hypertriton (Lambda + n + p). The long distances are treated carefully to achieve convergence and high accuracy. We use several sets of two-body interactions which reproduce the deuteron properties and provide the low-energy La

K. G. Chetyrkin

We present the results of the analytical evaluation of the massless four-loop O(alpha_s^3) correction to the correlator of the quark scalar currents and the Higgs decay rate into hadrons.

Stephan Elser, Burkhard Bunk

We report preliminary results for 2D massive QED with two flavours of Wilson fermions, using the Hermitean variant of Lüscher's bosonization technique. The chiral condensate and meson masses are obtained. The simplicity of the model allows for high statistics simulations close to the chiral and continuum limit, both in the quenched approximation and with

Kurt Langfeld

The classical Yang-Mills equation of motion is numerically investigated in the Lorentz gauge for a SU(2) gauge group. The color-electric field of two point-like charges is studied in the ''empty'' vacuum and in a state with an instanton present. The major effect for a fixed orientation of the instanton is that the color-electric field lines a

T. Brotz, C. Kiefer

We discuss semiclassical states in quantum gravity corresponding to Schwarzschild as well as Reissner Nordström black holes. We show that reduced quantisation of these models is equivalent to Wheeler-DeWitt quantisation with a particular factor ordering. We then demonstrate how the entropy of black holes can be consistently calculated from these states. Whil

A. A. Bytsenko, Guido Cognola, Sergio Zerbini

The functional determinant of Laplace-type operators on the 3-dimensional non-compact hyperbolic manifold with invariant fundamental domain of finite volume is computed by quadratures and making use of the related terms of the Selberg trace formula.

C. Brif

We introduce a set of coherent states which are associated with quantum systems governed by a trilinear boson Hamiltonian. These states are produced by the action of a nonunitary displacement operator on a reference state and can be equivalently defined by some eigenvalue equations. The system prepared initially in the reference state will evolve into the co

C. Brif, A. Mann

We study the phase sensitivity of SU(2) and SU(1,1) interferometers fed by two-mode field states which are intelligent states for Hermitian generators of the SU(2) and SU(1,1) groups, respectively. Intelligent states minimize uncertainty relations and this makes possible an essential reduction of the quantum noise in interferometers. Exact closed expressions

A. Stolin, P. P. Kulish

In this paper a class of new quantum groups is presented: deformed Yangians. They arise from rational solutions of the classical Yang-Baxter equation of the form $c_2 /u + const$ . The universal quantum $R$-matrix for a deformed Yangian is described. Its image in finite-dimensional representaions of the Yangian gives new matrix rational solutions of the Yang

Gustav W. Delius

The bicovariant differential calculi on quantum groups of Woronowicz have the drawback that their dimensions do not agree with that of the corresponding classical calculus. In this paper we discuss the first-order differential calculus which arises from a simple quantum Lie algebra. This calculus has the correct dimension and is shown to be bicovariant and c

U. Ornik, M. Plümer, B. R. Schlei, D. Strottman

The implications of the formation of a Bose condensate on one- and two-particle spectra are studied for ultrarelativistic nucleus-nucleus collisions in the framework of a hydrodynamic description. It is found that single particle spectra are considerably enhanced at low momenta. The Bose-Einstein correlation function has an intercept below two. For pion pair

Peter Scott, Gadde A. Swarup

We present an extension of Dunwoody's theory of tracks and use it to prove an analogue of the annulus theorem for hyperbolic groups.

Igor A. Bandos

In this short printed version of my talk I consider the generalized action for super-p-branes proposed previously in collaboration with D. Sorokin and Dmitrij V. Volkov. I describe briefly, the derivation doubly supersymmetric geometric approach from the generalized action and discuss one of the direction of its possible application.

Igor A. Bandos

The Lorentz harmonic formulation of D-dimensional bosonic p-brane theory with $D\geq (p+1)(p+2)/2$ coupled to an antisymmetric tensor field of rank d=(p+1) provides the dynamical ground for the description of d=(p+1) dimensional Gravity. It hence realizes the idea of Regge and Teitelboim on a 'string-like' description of gravity. The simplest nontriv

D. Fioravanti, A. Mariottini, E. Quattrini, F. Ravanini

We derive a generalization of the Destri - De Vega equation governing the scaling functions of some excited states in the Sine-Gordon theory. In particular configurations with an even number of holes and no strings are analyzed and their UV limits found to match some of the conformal dimensions of the corresponding compactified massless free boson. Quantum g

Paolo Di Vecchia

In these lectures we discuss various aspects of gauge theories with extended $N=2$ and $N=4$ supersymmetry that are at the basis of recently found exact results. These results include the exact calculation of the low energy effective action for the light degrees of freedom in the $N=2$ super Yang-Mills theory and the conjecture, supported by some checks, tha

G. V. Grigoryan, R. P. Grigoryan, I. V. Tyutin

A pseudoclassical theories of Majorana, Weyl and Majorana--Weyl particles in the space--time dimensions $D=2n$ are constructed. The canonical quantization of these theories is carried out and as a result we obtain the quantum mechanical description of neutral particle in $D=2n$ , Weyl particle in $D=2n$ and neutral Weyl particle in $D=4n+2$. In $D=2,4({\rm m

D. K. Park

Recently suggested causal principal value and causal prescriptions for the "spurious singularity" in light-cone gauge theories are nothing but the different guises of usual Mandelstam-Leibbrandt prescription.

John Ellis, G. L. Fogli, E. Lisi

An updated fit to the precision electroweak data and to the direct measurement of the top quark mass $m_t$ provides significant constraints on $m_t$ and on the Higgs boson mass $M_H$: $m_t/\text{GeV}=172\pm 6$ and $\log_{10}(M_H/\text{GeV})=2.16\pm 0.33$, with an error correlation $ρ=0.5$. We integrate the $(M_H, m_t)$ probability distribution found in this

Salman Habib, Emil Mottola, Peter Tinyakov

Winding number transitions in the two dimensional softly broken O(3) nonlinear sigma model are studied at finite energy and temperature. New periodic instanton solutions which dominate the semiclassical transition amplitudes are found analytically at low energies, and numerically for all energies up to the sphaleron scale. The Euclidean period beta of these

Biswajoy Brahmachari

One way to generate an intermediate scale being consistent with gauge coupling unification is to add new Higgs scalars above the intermediate scale. We classify such scenarios according to their degree of departure from minimal supersymmetric standard model. Thereafter, we summarize the results of a two-loop renormalization group analysis of the gauge and th

Michael S. Chanowitz

Models of strong $WW$ scattering in the $s$-wave can be represented in a gauge invariant fashion by defining an effective scalar propagator that represents the strong scattering dynamics. The $σ(qq \ra qqWW)$ signal may then be computed in U-gauge from the complete set of tree amplitudes, just as in the standard model, without using the effective $W$ approxi

R. Baier, Yu. L. Dokshitzer, A. H. Mueller, S. Peign

The medium-induced $p_{\perp}$-broadening and induced gluon radiation spectrum of a high energy quark or gluon traversing a large nucleus is studied. Multiple scattering of the high energy parton in the nucleus is treated in the Glauber approximation. We show that -dE/dz, the radiative energy loss of the parton per unit length, grows as L, the length of the

Maria Krawczyk, Jan Zochowski

Constraints on the general 2HDM ("Model II") are obtained from the existing $(g-2)_μ$ data including limits on Higgs bosons masses from LEP I data. We consider separately two cases: with a light scalar $h$ and with a light pseudoscalar $A$, assuming ${M_{h}+M_{A}} \ge {M_{Z}}$. The charged Higgs contribution is also included. It is found that already

M. Dittmar, H. Dreiner

We reconsider the signature of events with two charged leptons and missing energy as a signal for the detection of the Standard Model Higgs boson in the mass region M(Higgs)=155--180 GeV. It is shown that a few simple experimental criteria allow to distinguish events originating from the Higgs boson decaying to H --> W+W- from the non resonant production of

B. Kileng, P. Osland, P. N. Pandita

We present an analysis of the production and two-photon decay of the lightest CP-even Higgs boson of the Minimal Supersymmetric Standard Model (MSSM) at the Large Hadron Collider (LHC). A rather general model is considered, without supergravity constraints. All parameters of the model are taken into account, we especially study the dependence of the cross se

Rahul Sinha

We study CP violation in $B\to K^* \ell^+\ell^-$ using generalized Dalitz plot asymmetries in the angular distribution. These new kind of asymmetries are constructed by adding B and ${\bar B}$ events, and do not require flavor or time tagging, nor is the presence of strong phases needed. Using this method one requires about $2 \times 10^8/η$ B's to measu

Darwin Chang, W. -Y. Keung

New limits on couplings $λ^i_{jk}{''}$, which break both the baryon number and the $R$--parity, are derived by using a new mechanism that contributes to the neutron-anti-neutron oscillation. The constraints due to proton decay and its potential phenomenology are also reexamined.

K. Rummukainen

This talk reviews recent lattice results on the high $T$ electroweak phase transition. A remarkably accurate picture emerges: a) the transition is of first order for $m_H \lsim 80$GeV and vanishes for larger $m_H$; b) transition temperature, latent heat and interface tension are known, as well as c) the properties of the broken and symmetric phases. New deve

P. M. Vranas

It is known that domain wall fermions may be used in MC simulations of vector theories. The practicality and usefulness of such an implementation is investigated in the context of the vector Schwinger model, on a 2+1 dimensional lattice. Preliminary results of a Hybrid Monte Carlo simulation are presented.

E. Gregory, S. M. Catterall, G. Thorleifsson

We use the recently proposed node decimation algorithm for blocking dynamical geometries to investigate a class of models, with central charge greater than unity, coupled to 2D gravity. We demonstrate that the blocking preserves the fractal structure of the surfaces.

M. J. Bowick, S. M. Catterall, G. Thorleifsson

We study numerically the dynamical triangulation formulation of two-dimensional quantum gravity using a restricted class of triangulation, so-called minimal triangulations, in which only vertices of coordination number 5, 6, and 7 are allowed. A real-space RG analysis shows that for pure gravity (central charge c = 0) this restriction does not affect the cri

M. N. Chernodub, F. V. Gubarev, M. I. Polikarpov

We study a field--theoretical analogue of the Aharonov--Bohm effect in the 3D Abelian Higgs Model: the corresponding topological interaction is proportional to the linking number of the vortex and the particle world trajectories. We show that the Aharonov--Bohm effect gives rise to a nontrivial interaction of tested charged particles.

Andreas Frommer

We review the numerical analysis' understanding of Krylov subspace methods for solving (non-hermitian) systems of equations and discuss its implications for lattice gauge theory computations using the example of the Wilson fermion matrix. Our thesis is that mature methods like QMR, BiCGStab or restarted GMRES are close to optimal for the Wilson fermion m

Jae-Kwon Kim, D. P. Landau

Using a novel finite size scaling Monte Carlo technique, we calculate the four, six and eight point renormalized coupling constants defined at zero momentum for the three dimensional Ising system. Our values of the six and eight point coupling constants are significantly different from those obtained from other methods.

Aharon Levy

This is a review of the existing ideas in modelling the transition from the photoproduction ($Q^2 = 0$) to the deep inelastic scattering region. The available data of the proton structure function are analyzed from the point of view of the total $γ^* p$ cross section behavior with $W$ and the results are compared to different parameterizations. The question

K. Abe

Average charged multiplicities have been measured separately in $b$, $c$ and light quark ($u,d,s$) events from $Z^0$ decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of $b$ and light quark events, and reconstructed charmed mesons were used to select $c$ quark events. We measured the charged multi

S. Droz

Gravitational perturbations which are present in any realistic stellar collapse to a black hole, die off in the exterior of the hole, but experience an infinite blueshift in the interior. This is believed to lead to a slowly contracting lightlike scalar curvature singularity, characterized by a divergence of the hole's (quasi-local) mass function along t

Hugo Fort, Rodolfo Gambini, Jorge Pullin

We present an implementation of the loop representation of quantum gravity on a square lattice. Instead of starting from a classical lattice theory, quantizing and introducing loops, we proceed backwards, setting up constraints in the lattice loop representation and showing that they have appropriate (singular) continuum limits and algebras. The diffeomorphi

Carlo Rovelli

I summarize the basic ideas and formalism of loop quantum gravity. I illustrate the results on the discrete aspects of quantum geometry and two applications of these results to black hole physics. In particular, I discuss in detail a derivation of the Bekenstein-Hawking formula for the entropy of a black hole from first principles.

J. J. Rodríguez-Núñez, C. E. Cordeiro, A. Delfino

We constructed the one-particle spectral functions (diagonal and off-diagonal) which reproduce BCS for weak coupling and which take into account the effect of correlations on superconductivity in the attractive Hubbard model. The diagonal spectral function is composed of three peaks and the off-diagonal one is composed of two peaks. This ansatz satisfies the

Yong-Shi Wu, Yue Yu

We develop a field theory for a partially filled Landau level based on composite fermions with a finite vortex core, whose mean-field states are exactly those described by well-tested trial wave functions. Despite non-orthogonality of free composite-fermion states and non-Hermiticity of the mean-field Hamiltonian, a consistent perturbation theory is formulat

E. H. Lieb, M. Loss, H. Siedentop

A Thomas-Fermi-Weizsaecker type theory is constructed, by means of which we are able to give a relatively simple proof of the stability of relativistic matter. Our procedure has the advantage over previous ones in that the critical value of the fine structure constant, alpha, is raised to 0.77 (recall that the critical value is known to be less than 2.72). W

Barbara Di Eugenio

In this paper, I give an account of some phenomena of pronominalization in Italian in terms of centering theory. After a general introduction to the Italian pronominal system, I will review centering, and then show how the original rules have to be extended or modified. Finally, I will show that centering does not account for two phenomena: first, the functi

Barbara Di Eugenio

This paper examines the discourse functions that different types of subjects perform in Italian within the centering framework. I build on my previous work (COLING90) that accounted for the alternation of null and strong pronouns in subject position. I extend my previous analysis in several ways: for example, I refine the notion of {\sc continue} and discuss

Barbara Di Eugenio

This paper explores the correlation between centering and different forms of pronominal reference in Italian, in particular zeros and overt pronouns in subject position. Such correlations, that I had proposed in earlier work (COLING 90), are verified through the analysis of a corpus of naturally occurring texts. In the process, I extend my previous analysis

Francois Yvon

We present in this paper an original extension of two data-driven algorithms for the transcription of a sequence of graphemes into the corresponding sequence of phonemes. In particular, our approach generalizes the algorithm originally proposed by Dedina and Nusbaum (D&N) (1991), which had originally been promoted as a model of the human ability to pronounce

Dennis Bonatsos, C. Daskaloyannis, G. A. Lalazissis, S. B. Drenska

It is shown that the recently observed $ΔI=4$ bifurcation seen in superdeformed nuclear bands is also occurring in rotational bands of diatomic molecules. In addition, signs of a $ΔI=8$ bifurcation, of the same order of magnitude as the $ΔI=4$ one, are observed both in superdeformed nuclear bands and rotational bands of diatomic molecules.

M. J. Sánchez, E. Vergini, D. A. Wisniacki

This paper is concerned with the study of one-body dissipation effects in idealized models resembling a nucleus. In particular, we study the quantum mechanics of a free particle that collides elastically with the slowly moving walls of a Bunimovich stadium billiard. Our results are twofold. First, we develop a method to solve in a simple way the quantum mech

Eric Peng

Recent discussion of the effects of finite source size on high magnification microlensing events due to MACHOs motivates a study into the feasibility of observing such effects and extracting the source radius. Simulated observations are generated by adding Gaussian error to points sampled on theoretical microlensing light curves for a limb darkened, extended

Peter A. Becker, Menas Kafatos

We develop a general expression for the gamma-gamma absorption coefficient for gamma-rays propagating in an arbitrary direction at an arbitrary point in space above an X-ray emitting accretion disk. The X-ray intensity is assumed to vary as a power law in energy and radius between the outer disk radius and the inner radius, which is the radius of marginal st

Bohdan Paczynski

Detached eclipsing double line spectroscopic binaries offer an opportunity to measure directly stellar parameters: mass, luminosity, radius, as well as the distance. The only non-trivial step is the need to determine surface brightness of each component on the basis of something measurable, like the color or the line ratios. Modern model atmospheres provide

S. Sigurdsson, M. J. Rees

A significant fraction of the stellar population in the cusp around central black holes of galaxies consists of compact remnants of evolved stars, such as white dwarfs, neutron stars and stellar mass black holes. We estimate the rate of capture of compact objects by massive central black holes, assuming most spiral galaxies have a central black hole of modes

R. van Ojik, H. J. A. Röttgering, G. K. Miley, R. W. Hunstead

We present intermediate resolution ($\sim3$ Å) spectra of the Ly$α$ emission from 15 high redshift radio galaxies ($z>2$). Together with previously published spectra we analyze data for a sample of 18 objects. In 11 of the 18 radio galaxies we find deep troughs in the Ly$α$ emission profile, which we interpret as H\,{\sc i} absorption with column densities i

Elizabeth Barton, Margaret J. Geller, Massimo Ramella, Ronald O. Marzke

For the first time, we construct a catalog of compact groups selected from a complete, magnitude-limited redshift survey. We select groups with $N \geq 3$ members based on projected separation and association in redshift space alone. We evaluate the characteristics of the Redshift Survey Compact Groups (RSCG's). Their physical properties (membership freq

V. G. Bezchastnov, P. Haensel

We derive exact expressions for the cross section of neutrino scattering on electrons in dense, hot stellar matter, in the presence of strong magnetic fields. Numerical calculations of the scattering cross sections at various densities, temperatures and magnetic fields, are performed. Strong, quantizing magnetic fields modify significantly the angular and en

A. G. A. Brown, W. Verschueren

We investigate the rotational velocities of early-type stars in the Sco OB2 association. We measure \vsini\ for 156 established and probable members of the association. The measurements are performed with three different techniques, which are in increasing order of expected \vsini: 1) converting the widths of spectral lines directly to \vsini, 2) comparing a

C. R. Gwinn, M. J. Ojeda, M. C. Britton, J. E. Reynolds

We use interstellar scattering of the Vela pulsar to determine the size of its emission region. From interferometric phase variations on short baselines, we find that radio-wave scattering broadens the source by 3.4+/-0.3 milliarcseconds along the major axis at position angle 81+/-3 degrees. The ratio of minor axis to major axis is 0.51+/-0.03. Comparison of

Chongying Dong, Haisheng Li, Geoffrey Mason

Let $V$ be a simple vertex operator algebra which admits the continuous, faithful action of a compact Lie group $G$ of automorphisms. We establish a Schur-Weyl type duality between the unitary, irreducible modules for $G$ and the irreducible modules for $V^G$ which are contained in $V$ where $V^G$ is the space of $G$-invariants of $V.$ We also prove a concom

Nathan Seiberg, Stephen Shenker

We study the hypermultiplet moduli space of the type II string compactified on a Calabi-Yau space $\bX$. We do this by using IIA/IIB duality in a compactification of the same theory on $\bX\times \bS ^1$ and by using recent results on three dimensional field theory.

Werner M. Vieira, Patricio S. Letelier

We find that the model of a black hole plus an exterior halo of quadrupoles and octopoles recently proposed by us is more chaotic than previously detected. In fact, the quadrupolar component gives rise also to a chaotic behavior, found after further numerical search. This fact reinforces even more the role of chaos in relativistic core--halo models.

Moshe Elitzur, Zeljko Ivezic

Infrared emission from radiatively heated dust possesses general scaling properties. The spectral shape is independent of overall luminosity when the inner boundary of the dusty region is controlled by dust sublimation; the only relevant property of the heating radiation is its frequency profile. For a given type of dust grains, the emission from red giants

B. Schroer

We present illustrations which show the usefulness of algebraic QFT. In particular in low-dimensional QFT, when Lagrangian quantization does not exist or is useless (e.g. in chiral conformal theories), the algebraic method is beginning to reveal its strength.

B. T. Jannuzi, G. F. Hartig, S. Kirhakos, W. L. W. Sargent

We report the discovery of a high-ionization broad absorption line system at a redshift of z_abs=0.695 in the spectrum of the z_em=1.052 radio-quiet quasar PG 2302+039. Broad absorption with FWHM from 3,000 to 5,000 km/s is detected from C IV, N V, and O VI in HST Faint Object Spectrograph spectra of the quasar. A narrow line system (FWHM approximately 250 k

D. G. Barci, E. S. Fraga, C. A. A. de Carvalho

We present a study of the role of fermions in the decay of metastable states of a scalar field via bubble nucleation. We analyze both one and three-dimensional systems by using a gradient expansion for the calculation of the fermionic determinant. The results of the one-dimensional case are compared to the exact results of previous work.

Uwe C. Täuber, David R. Nelson

The influence of different types of disorder (both uncorrelated and correlated) on the superfluid properties of a weakly interacting or dilute Bose gas, as well as on the corresponding quantities for flux line liquids in high-temperature superconductors at low magnetic fields are reviewed, investigated and compared. We exploit the formal analogy between supe

Tom H. Koornwinder

This paper is mostly a survey, with a few new results. The first part deals with functional equations for q-exponentials, q-binomials and q-logarithms in q-commuting variables and more generally under q-Heisenberg relations. The second part discusses translation invariance of Jackson integrals, q-Fourier transforms and the braided line.

UKQCD Collaboration, H. P. Shanahan, C. T. H. Davies, K. C. Bowler

We compute the light hadron mass spectrum at beta=5.7 using the O(a) improved Sheikholeslami-Wohlert (SW) fermion action with two choices of the clover coefficient: the classical value, c=1, and a mean-field or tadpole-improved estimate c=1.57. We compare our results with those of the GF11 Collaboration who use the Wilson fermion action (c=0). We find that c

Ralph A. M. J. Wijers

A specific class of pulsar recycling model, in which magnetic-field decrease is a function only of the amount of mass accreted onto the neutron star, is examined in detail. It is shown that no model in this class is consistent with all available data on X-ray binaries and recycled pulsars. Only if all constraints are stretched to their limit and a few object

Renyue Cen

We study the projection effects on various observables of clusters of galaxies at redshift near zero, including cluster richness, velocity dispersion, X-ray luminosity, three total mass estimates (velocity-based, temperature-based and gravitational lensing derived), gas fraction and substructure. Unlike previous studies focusing on the Abell clusters, we con