September 1999 arXiv papers — page 19

UKQCD Collaboration, Craig McNeile, Alan Irving, Chris Michael

We investigate a number of algorithms that calculate the quark propagators for the overlap-Dirac fermion operator. The QCD simulations were performed at beta = 5.9 with a lattice volume of 16**3*32.

P. Jönsson, M. F. Hansen, P. Nordblad

Non-equilibrium dynamics in an interacting Fe-C nanoparticle sample, exhibiting a low temperature spin glass like phase, has been studied by low frequency ac-susceptibility and magnetic relaxation experiments. The non-equilibrium behavior shows characteristic spin glass features, but some qualitative differences exist. The nature of these differences is disc

Eli Waxman, John Bahcall

We show that a significant fraction of the energy of a gamma-ray burst(GRB) is probably converted to a burst of 10^{17}-10^{19} eV neutrinos and multiple GeV gammas that follow the GRB by > 10 s . If, as previously suggested, GRB's accelerate protons to ~10^{20} eV, then both the neutrinos and the gammas may be detectable.

H. Osborn, G. M. Shore

An analysis of one and two point functions of the energy momentum tensor on homogeneous spaces of constant curvature is undertaken. The possibility of proving a $c$-theorem in this framework is discussed, in particular in relation to the coefficients $c,a$, which appear in the energy momentum tensor trace on general curved backgrounds in four dimensions. War

R. Folk, Yu. Holovatch, T. Yavors'kii

We present a field-theoretical treatment of the critical behavior of three-dimensional weakly diluted quenched Ising model. To this end we analyse in a replica limit n=0 5-loop renormalization group functions of the $ϕ^4$-theory with O(n)-symmetric and cubic interactions (H.Kleinert and V.Schulte-Frohlinde, Phys.Lett. B342, 284 (1995)). The minimal subtracti

J. Cserti

We calculate the resistance between two arbitrary grid points of several infinite lattice structures of resistors by using lattice Green's functions. The resistance for $d$ dimensional hypercubic, rectangular, triangular and honeycomb lattices of resistors is discussed in detail. We give recurrence formulas for the resistance between arbitrary lattice po

Ryotaro Arita, Kazuhiko Kuroki, Hideo Aoki

In order to identify the most favorable situation for superconductivity in the repulsive single-band Hubbard model, we have studied instabilities for d-wave pairing mediated by antiferromagnetic spin fluctuations and p-pairing mediated by ferromagnetic fluctuations with the fluctuation exchange approximation in both two dimensions and three dimensions. By sy

Stephen L. Adler, Lawrence P. Horwitz

Hughston has recently proposed a stochastic extension of the Schrödinger equation, expressed as a stochastic differential equation on projective Hilbert space. We derive new projective Hilbert space identities, which we use to give a general proof that Hughston's equation leads to state vector collapse to energy eigenstates, with collapse probabilities g

Toshihiko Ono

This paper proposes a basic theory on physical reality, and a new foundation for quantum mechanics and classical mechanics. It does not only solve the problem of the arbitrariness on the operator ordering for the quantization procedure, but also clarifies how the classical-limit occurs. It further compares the new theory with the known quantization methods,

Constantin Brif

We study the thermal-noise spectrum of multi-loop pendulum suspensions for test masses in interferometric gravitational-wave detectors. The dependence of the thermal noise on suspension parameters and on properties of the wire material is discussed for the situation in which the losses are dominated by the internal friction in the pendulum wires.

Constantin Brif

The thermal noise is expected to be one of the main limiting factors on the sensitivity of interferometric gravitational-wave detectors like LIGO and VIRGO. Thermal fluctuations of internal modes of the interferometer's test masses and of suspension modes will dominate the noise spectrum at the important frequency range between 50 and 200 Hz. It is assum

Yu. M. Sinyukov, S. V. Akkelin, R. Lednicky

Using the method of locally equilibrium statistical operator we consider the thermalized relativistic quantum fields in an oscillatory trap. We compare this thermal picture of the confined boson gas with non-relativistic model of independent factorized sources. We find that they are equivalent in the limit of very large effective sizes $R$, more exactly, whe

Omar Benhar, Adelchi Fabrocini

The two-nucleon spectral function in nuclear matter is studied using Correlated Basis Function perturbation theory, including central and tensor correlations produceded by a realistic hamiltonian. The factorization property of the two-nucleon momentum distribution into the product of the two single nucleon distributions shows up in an analogous property of t

Bobby Eka Gunara

We construct the general supersymmetry algebra via the adjoint action on a semi-Hopf algebra which has a more general structure than a Hopf algebra. As a result we have an extended supersymmetry theory with quantum gauge group, i.e., quantised enveloping algebra of a simple Lie algebra. For the example, we construct the N=1 and generalized N=2 supersymmetry

Andrew Granville, K. Soundararajan

Let S be a subset of the unit disk, and let F(s) denote the class of completely multiplicative functions f such that f(p) is in S for all primes p. The authors&#39; main concern is which numbers arise as mean-values of functions in F(s). More precisely, let Gamma_N(S) = {1/N sum_{n <= N} f(n): f in F(S)} and Gamma(S) = lim_{N -> infinity} Gamma_N(s). The aut

Roger J. McDermott, Deepak Parashar

It is known that the inhomogeneous quantum group IGL_{q,r}(2) can be constructed as a quotient of the multiparameter q-deformation of GL(3). We show that a similar result holds for the inhomogeneous Jordanian deformation and exhibit its Hopf structure.

A. Schilling, S. O. Warnaar

A generalization of the q-(Pfaff)-Saalschutz summation formula is proved. This implies a generalization of the Burge transform, resulting in an additional dimension of the ``Burge tree&#39;&#39;. Limiting cases of our summation formula imply the (higher-level) Bailey lemma, provide a new decomposition of the q-multinomial coefficients, and can be used to pro

Ralf Schindler

We isolate a new large cardinal concept, &#34;remarkability.&#34; Consistencywise, remarkable cardinals are between ineffable and omega-Erdos cardinals. They are characterized by the existence of &#34;0^sharp-like&#34; embeddings; however, they relativize down to L. It turns out that the existence of a remarkable cardinal is equiconsistent with L(R) absolute

C. Robin Graham

This article describes some geometric invariants and conformal anomalies for conformally compact Einstein manifolds and their minimal submanifolds which have recently been discovered via the Anti-de Sitter/Conformal Field Theory correspondence.

Olivier Schiffmann

We prove that the Hall algebra U^-_n of the cyclic quiver of type A^(1)_{n-1} decomposes as a direct product of the quantum negative nilpotent subalgebra U_q^-(\hat{sl}_{n)) and C[q,q^{-1},z_1,z_2...]. We use this to prove a conjecture of Varagnolo and Vasserot in math/9803023 relating the canonical basis of U^-_n and the canonical basis of the level 1 Fock

R. Gianvittorio, A. Restuccia, J. F. Sanchez

A non-abelian topological quantum field theory describing the scattering of self-dual field configurations over topologically non-trivial Riemann surfaces, arising from the reduction of 4-dim self-dual Yang-Mills fields, is introduced. It is shown that the phase space of the theory can be exactly quantized in terms of the space of holomorphic structures over

Emil J. Martinec

Introductory lectures on the relations between the thermodynamics of gauge theory on branes and black holes, including the correspondence principle of Horowitz and Polchinski, the AdS/CFT conjecture, and matrix theory.

Ichiro Oda

We construct a model consisting of many D3-branes with only positive tension in a five-dimensional anti-de Sitter space-time geometry. It is shown that this type of model naturally realizes not only exponential mass hierarchy between the Planck scale and the electroweak scale but also trapping of the graviton on the D3-branes. It is pointed out that our mode

J. F. Bennett, J. A. Gracey

We renormalize to three loops a version of the Thirring model where the fermion fields not only lie in the fundamental representation of a non-abelian colour group SU(N_c) but also depend on the number of flavours, N_f. The model is not multiplicatively renormalizable in dimensional regularization due to the generation of evanescent operators which emerge at

Qiong-gui Lin

Neutral fermions of spin 1/2 with magnetic moment can interact with electromagnetic fields through nonminimal coupling. In 2+1 dimensions the electromagnetic field strength plays the same role to the magnetic moment as the vector potential to the electric charge. This duality enables one to obtain physical results for neutral particles from known ones for ch

Robin Horan, Martin Lavelle, David McMullan

A crucial element of scattering theory and the LSZ reduction formula is the assumption that the coupling vanishes at large times. This is known not to hold for the theories of the Standard Model and in general such asymptotic dynamics is not well understood. We give a description of asymptotic dynamics in field theories which incorporates the important featu

Anjan Kundu

Exploiting the quantum integrability condition we construct an ancestor model associated with a new underlying quadratic algebra. This ancestor model represents an exactly integrable quantum lattice inhomogeneous anisotropic model and at its various realizations and limits can generate a wide range of integrable models. They cover quantum lattice as well as

Vipul Periwal

Polyakov has conjectured that Yang-Mills theory should be equivalent to a noncritical string theory. I pointed out, based on the work of Marchesini, Ishibashi, Kawai and collaborators, and Jevicki and Rodrigues, that the loop operator of the Yang-Mills theory is the temporal gauge string field theory Hamiltonian of a noncritical string theory. In the present

Alan Chodos, Fred Cooper, Wenjin Mao, Hisakazu Minakata

We generalize our previous model to an O(N) symmetric two-dimensional model which possesses chiral symmetry breaking and superconducting (Cooper pair condensates) phases at large-N. At zero temperature and density, the model can be solved analytically in the large-N limit. We perform the renormalization explicitly and obtain a closed form expression of the e

C. Royon

The BFKL dynamics can be successfully tested at the future high energy $e^+e^-$ linear collider. The total $γ^*γ^*$ cross-section is calculated in the Leading Log QCD dipole picture of BFKL dynamics, and compared with the one from 2-gluon exchange. The rapidity dependence of the cross-section remains a powerful tool to increase the ratio between the BFKL and

Salvatore Mele, Eusebio Sanchez

Recent theoretical scenarios propose that quantum gravity effects may manifest at LEP energies by means of gravitons that couple to Standard Model particles and propagate into extra space dimensions. These predictions are checked against the most recent experimental results on photon, W and Z pair production. No deviations from the Standard Model expectation

I. Vendramin

We consider a particular two-Higgs-doublet model with spontaneous CP violation, where two neutral Higgses have no definite CP properties and the third one is CP-even. In this model, as the parameter $θ$ of CP violation increases, the masses of the neutral Higgs bosons are drawn towards the mass of the lightest one and the chance of detection of neutral Higgs

D. Dominici

A recent experimental determination of the weak charge of atomic cesium is used to get implications for possible new physics. The new data imply positive upper and lower bounds on the new physics contribution to the weak charge, delta_N Q_W, requiring new physics of a type not severely constrained by the high energy precision data.

Pietro Santorelli, Egidio Scrimieri

We discuss a new method to solve in a semianalytical way the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations at NLO order in the x-space. The method allows to construct an evolution operator expressed in form of a rapidly convergent series of matrices, depending only on the splitting functions. This operator, acting on a generic initial distri

Gideon Alexander, Iuliana Cohen

The emission volume sizes of pions and Kaons, r_{π^\pm π^\pm} and r_{K^\pm K^\pm}, measured in the hadronic Z^0 decays via the Bose-Einstein Correlations (BEC), and the recent measurements of r_{ΛΛ} obtained by through the Pauli exclusion principle are used to study the r dependence on the hadron mass. A clear r_{π^\pm π^\pm} > r_{K^\pm K^\pm} > r_{ΛΛ} hiera

E. A. Kuraev, J. Manjavidze, A. Sissakian

The idea that the hard processes are dominate at the very high multiplicity (VHM) final states creation is considered. For this purpose quantitative realization of the Pomeron, DIS and large-angle annihilation (LAA) mechanism combinations are considered in the pQCD frame. The phase transition (condensation) in the soft pions system is described as the altern

D. Dominici

The capability of the linear collider to discover and study the lightest neutral pseudo-Nambu-Goldstone boson P_0 of dynamical symmetry breaking models in the e+e- and gamma gamma modes is presented. For a number of technicolor N_TC=4, the discovery of the P_0 at an e+e- collider via the reaction e+e- -> gamma P_0 should be possible for an integrated luminos

M. Knecht, H. Neufeld, H. Rupertsberger, P. Talavera

We construct a low-energy effective field theory which allows the full treatment of isospin-breaking effects in semileptonic weak interactions. To this end, we enlarge the particle spectrum of chiral perturbation theory with virtual photons by including also the light leptons as dynamical degrees of freedom. Using super-heat-kernel techniques, we determine t

Armin Boehrer

The photon structure function F2gamma has been measured with data taken by the ALEPH collaboration at LEP centre-of-mass energies sqrt s = 91 GeV with < Q^2 > of 9.9, 20.7 and 284 GeV^2 and sqrt s = 183 GeV with < Q^2 > of 13.7 and 56.5 GeV^2. For the data at sqrt s = 183 GeV a two-dimensional unfolding method employing the principle of maximum entropy is us

Da-Shin Lee, Kin-Wang Ng

Using the non-equilibrium quantum field theory, photon production from the coherently oscillating axion field in a flat Robertson-Walker cosmology is re-examined. First neglecting the Debye screening of the baryon plasma to photons, we find that the axions will dissipate into photons via spinodal instability in addition to parametric resonance. As a result o

Yasunori Nomura

The supersymmetric flavor problem is elegantly solved by the decoupling scenario, where the first-two generation sfermions are much heavier than the third generation ones. However, such a mass spectrum is not stable against renormalization group evolution and causes extreme fine-tuning of the electroweak symmetry breaking. We present a mechanism which stabil

P. G. Mercadante, H. Yamamoto

We performed an analysis on the detection of a long lived stau at a linear collider with $\sqrt{s}=500$ GeV. In GMSB models a long lived NLSP is predicted for large value of the supersymmetry breaking scale F. Furthermore in a large portion of the parameter space this particle is a stau. Such heavy charged particles will leave a track in the tracking volume

O. Jahn, F. Lenz, J. W. Negele, M. Thiele

We study the relation between center vortices and instantons in lattice QCD.

Romuald A. Janik, Maciej A. Nowak, Gabor Papp, Ismail Zahed

We investigate the effects of several Abelian external fluxes $ϕ$, on the Euclidean Dirac spectrum of light quarks in QCD with two colors. Our results provide for a novel way of assessing the pion weak decay constant directly from spectral fluctuations, and discriminating a flux-rich from a flux-poor vacuum, using QCD lattice simulations.

H. Banerjee, Asit K. De

In the axial Ward identity of lattice QED we show that in the limit of infinite fermion mass m the pseudoscalar density term exactly cancels the Adler-Bell-Jackiw anomaly. Using this result we calculate the U(1) axial anomaly in a non-abelian gauge theory.

A. Borici

In this talk I propose a new computational scheme with overlap fermions and a fast algorithm to invert the corresponding Dirac operator.

P. Cea, L. Cosmai

We investigate the dynamics of lattice gauge theories in an Abelian monopole background field. By means of the gauge-invariant lattice Schrodinger functional we study the Abelian monopole condensation in U(1) lattice gauge theory at zero temperature and in SU(3) lattice gauge theory at finite temperature.

P. Cea, M. Consoli, L. Cosmai

In the Standard Model the Fermi constant is associated with the vacuum expectation value of the Higgs field, `the condensate&#39;, usually believed to be a cutoff-independent quantity. General arguments related to the `triviality&#39; of $Φ^4$ theory in 4 space-time dimensions suggest, however, a dramatic renormalization effect in the continuum limit that is

D. Bodeker, G. D. Moore, K. Rummukainen

We measure the sphaleron rate (topological susceptibility) of hot SU(2) gauge theory, using a lattice implementation of the hard thermal loop (HTL) effective action. The HTL degrees of freedom are implemented by an expansion in spherical harmonics and truncation. Our results for the sphaleron rate agree with the parametric prediction of Arnold, Son and Yaffe

J. L. Alonso, Ph. Boucaud, J. M. Carmona, J. L. Cortes

We present a way of protecting a Dirac fermion interacting with a scalar (Higgs) field from getting a mass from the vacuum. It is obtained through an implementation of translational symmetry when the theory is formulated with a momentum cutoff, which forbids the usual Yukawa term. We consider that this mechanism can help to understand the smallness of neutri

PACS Collaboration, A. Ali Khan, S. Aoki, R. Burkhalter

We present results on an analysis of the decay constants f_B and f_Bs with two flavours of sea quark. The calculation has been carried out on 3 different bare gauge couplings and 4 sea quark masses at each gauge coupling, with m_pi/m_rho ranging from 0.8 to 0.6. We employ the Fermilab formalism to perform calculations with heavy quarks whose mass is in the r

V. Bornyakov, A. Hoferichter, G. Schierholz, A. Thimm

We address the problem of numerical simulations in the background non-trivial topology in the chiral Schwinger model. An effective fermionic action is derived which is in accord with established analytical results, and which satisfies the anomaly equation. We describe a numerical evaluation of baryon number violating amplitudes, specifically the &#39;t Hooft

PACS Collaboration, A. Ali Khan, S. Aoki, G. Boyd

We present updated results of the CP-PACS calculation of the light hadron spectrum in $N_{\rm f}=2$ full QCD. Simulations are made with an RG-improved gauge action and a tadpole-improved clover quark action for sea quark masses corresponding to $m_{\rm PS}/m_{\rm V} \approx 0.8$--0.6 and the lattice spacing $a=0.22$--0.09 fm. A comparison of the full QCD spe

PACS Collaboration, A. Ali Khan, S. Aoki, Y. Aoki

We investigate the existence of chiral zero modes at a^{-1} \simeq 1 GeV in quenched domain-wall QCD. Simulations are carried out for the plaquette and an RG-improved gauge actions on a 12^3x24xN_s lattice with N_s=10-50. We find that the pion mass in the chiral limit remains non-vanishing as N_s\to\infty for both gauge actions. Possible origins of this non-

Sinya Aoki, Taku Izubuchi, Junichi Noaki, Yoshinobu Kuramashi

We calculate one-loop renormalization factors of several quark operators including bilinear, three- and four-quark operator for domain-wall fermion action. Since Green functions are constructed for external physical quark fields, our renormalization method is simple and can be easily applied to calculation of any quark operators. Our results show that these

Stephan Dürr

I give an outline of my proposal to take the QCD functional determinant in lattice simulations partially into account: The determinant is split into two factors, the factor referring to a standard background in each topological sector is kept exactly, the factor describing the effect of the smooth deviation of the actual configuration from the reference back

Stephan Dürr

I give a quick summary of my proposal for simulating an improvement on quenched QCD with dynamical fermions which interact with the gluon configuration only via the topological index of the latter. It amounts to include only the topological part of the functional determinant into the measure, thereby absorbing a correction factor into the observable. I discu

The WA102 Collaboration, D. Barberis

Evidence is presented that the Pomeron act as a non-conserved vector current. A study has been made of the azimuthal angle phi, which is defined as the angle between the pT vectors of the two outgoing protons, in the reaction pp -> pp(X0) for those resonances (X0) which are compatible with being produced by double Pomeron exchange. These distributions have b

Keith H. Lockitch

Despite the recent excitement over the r-mode instability of rotating stars, these modes are not yet well-understood for stellar models appropriate to neutron stars - perfect fluid models in which both the equilibrium and perturbed configurations obey the same one-parameter equation of state. In spherical stars of this kind, r-modes and g-modes form a degene

Israel Cidon, Osnat Mokryn

Broadcast networks are often used in modern communication systems. A common broadcast network is a single hop shared media system, where a transmitted message is heard by all neighbors, such as some LAN networks. In this work we consider a more complex environment, in which a transmitted message is heard only by a group of neighbors, such as Ad-Hoc networks,

Krzysztof R. Apt, Eric Monfroy

We study here constraint satisfaction problems that are based on predefined, explicitly given finite constraints. To solve them we propose a notion of rule consistency that can be expressed in terms of rules derived from the explicit representation of the initial constraints. This notion of local consistency is weaker than arc consistency for constraints of

Krzysztof R. Apt

We provide here a simple, yet very general framework that allows us to explain several constraint propagation algorithms in a systematic way. In particular, using the notions commutativity and semi-commutativity, we show how the well-known AC-3, PC-2, DAC and DPC algorithms are instances of a single generic algorithm. The work reported here extends and simpl

Tarjin Rahman, Paul Muter

The electronic presentation of text in small display windows is mushrooming. In the present paper, four ways of presenting text in a small display window were examined and compared to a Normal Page condition: rapid serial visual presentation (RSVP), RSVP with a Completion Meter, Sentence-by-Sentence presentation, and Sentence-by-Sentence presentation with a

M. Buttiker

A discussion of recent work on time-dependent transport in mesoscopic structures is presented. The discussion emphasizes the use of time-dependent transport to gain information on the charge distribution and its collective dynamics. We discuss the RC-time of mesoscopic capacitors, the dynamic conductance of quantum point contacts and dynamic weak localizatio

I. Alexandrou, M. Baxendale, G. A. J. Amaratunga, N. L. Rupesinghe

A modified cathodic arc technique has been used to deposit carbon nitride thin films directly on n+ Si substrates. Transmission Electron Microscopy showed that clusters of fullerene-like nanoparticles are embedded in the deposited material. Field emission in vacuum from as-grown films starts at an electric field strength of 3.8 V/micron. When the films were

U. Klein, D. Rainer, H. Shimahara

Clean superconductors with weakly coupled conducting planes have been suggested as promising candidates for observing the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. We consider here a layered superconductor in a magnetic field of arbitrary orientation with respect to the conducting plane. In this case there is competition of spin-pair-breaking and orbita

M. Furlan, T. Heinzel, B. Jeanneret, S. V. Lotkhov

The distribution of nearest-neighbour spacings of Coulomb blockade oscillation peaks in normal conducting aluminum single electron transistors is found to be non-Gaussian. A pronounced tail to reduced spacings is observed, which we attribute to impurity-specific parametric charge rearrangements close to the transistor. Our observation may explain the absence

Y. Asano

The mechanism of the magnetoconductance oscillations in junctions of a ballistic semiconductor and a superconductor is discussed. The oscillations appear when both the normal and the Andreev reflection occur at the interface. The interplay between the classical cyclotron motion of a quasiparticle and the phase shift caused by the magnetic field is the origin

T. Ozaki, M. Aoki, D. G. Pettifor

The theory of a novel bond-order potential, which is based on the block Lanczos algorithm, is presented within an orthogonal tight-binding representation. The block scheme handles automatically the very different character of sigma and pi bonds by introducing block elements, which produces rapid convergence of the energies and forces within insulators, semic

W. Ihra, M. Leadbeater, J. L. Vega, K. Richter

We study the effect on the density of states in mesoscopic ballistic billiards to which a superconducting lead is attached. The expression for the density of states is derived in the semiclassical S-matrix formalism shedding insight into the origin of the differences between the semiclassical theory and the corresponding result derived from random matrix mod

A. O. Gogolin, A. A. Nersesyan, A. M. Tsvelik

This volume provides a detailed account of bosonization. The first part of the book examines the technical aspects of bosonization including one-dimensional fermions, the Gaussian model, the structure of Hilbert space in conformal theories, Bose-Einstein condensation in two dimensions, non-Abelian bosonization, and the Ising and WZNW models. The second part

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

The quantum-limited linewidth of a laser cavity is enhanced above the Schawlow-Townes value by the Petermann factor K, due to the non-orthogonality of the cavity modes. The average Petermann factor $<K>$ in an ensemble of cavities with chaotic scattering and broken time-reversal symmetry is calculated non-perturbatively using random-matrix theory and the sup

T. M. Tauris, R. P. Fender, E. P. J. van den Heuvel, H. M. Johnston

We have analyzed the kinematical parameters of Cir X-1 to constrain the nature of its companion star, the eccentricity of the binary and the pre-supernova parameter space. We argue that the companion is most likely to be a low-mass (< 2.0 M_sun) unevolved star and that the eccentricity of the orbit is 0.94 +/- 0.04. We have evaluated the dynamical effects of

B. Link, R. I. Epstein, J. M. Lattimer

With the aim of constraining the structural properties of neutron stars and the equation of state of dense matter, we study sudden spin-ups, glitches, occurring in the Vela pulsar and in six other pulsars. We present evidence that glitches represent a self-regulating instability for which the star prepares over a waiting time. The angular momentum requiremen

S. Prunet, A. Blanchard

In this paper we investigate the overcooling problem and propose some possible solutions. We show that the overcooling problem is generic to the hierarchical picture of structure formation, as long as the cooling is actually possible in small halos at high redshift. Solutions to this problem are likely to be associated with some feedback mechanism, and proba

J. Robert Buchler

We review the numerical modelling of the nonlinear pulsations of classical variable stars with hydrocodes that include the effects of turbulent convection. Despite their simplicity these turbulent convective recipes appear to remove many of the difficulties that radiative codes faced. In particular, the numerical modelling of double mode pulsations has becom

L. D. Matthews, J. S. Gallagher, W. van Driel

We present B- and R-band imaging and photometry, H-alpha narrow-band imaging, NIR H-band imaging, and HI 21-cm spectroscopy of the nearby Sd spiral galaxy UGC7321. UGC7321 exhibits a remarkably thin stellar disk with no bulge component. The galaxy has a very diffuse, low surface brightness disk, which appears to suffer little internal extinction in spite of

K. Beuermann

Recent theoretical and observational progress has substantially improved the definition of the lower main sequence and established a new basis for a comparison of main sequence stars and the secondaries in CVs. The evolutionary sequences of Kolb & Baraffe [1999] imply that the secondaries in many CVs are expanded compared with main sequence stars of the same

J. Reunanen, J. K. Kotilainen, S. Laine, S. D. Ryder

We present high spatial resolution near-infrared broad-band JHK images and, for the first time, BrGamma 2.1661 micron and H_2 1-0 S(1) 2.122 micron emission line images of the circumnuclear star forming ring (major axis diameter 7&#34; = 2 kpc) in the starburst galaxy NGC 7771. These data are used to investigate the morphology and extinction of the starburst

S. Randich

Focusing on ROSAT results for clusters in the $\sim 20-600$ Myr range, I first summarize our current understanding of the X-ray activity - rotation - age relationship. Then, the problem of the Hyades K and M dwarfs binaries is addressed: 1. most K and M-type binaries in wide systems are X-ray brighter than single stars; 2. binaries seem to fit into the same

A. N. Parmar, T. Oosterbroek, M. Guainazzi, A. Segreto

During a BeppoSAX observation of the X-ray source X1746-371 located in the globular cluster NGC6441 a type I X-ray burst, parts of 4 intensity dips, and energy dependent flaring were detected. The dips repeat every 5.8 +0.3 -0.9 hr and show no obvious energy dependence. If the dips are due to electron scattering this energy independence implies an abundance

Andrew A. Cole, Kenneth Wood, Kenneth H. Nordsieck

Motivated by new sounding-rocket wide-field polarimetric images of the Large Magellanic Cloud, we have used a three-dimensional Monte Carlo radiation transfer code to investigate the escape of near-ultraviolet photons from young stellar associations embedded within a disk of dusty material (i.e. a galaxy). As photons propagate through the disk, they may be s

Andrew A. Cole, Kenneth H. Nordsieck, Steven J. Gibson, Walter M. Harris

We have used the rocket-borne Wide-Field Imaging Survey Polarimeter (WISP) to image a 1.5 deg. by 4.8 deg. area of the western side of the LMC at a wavelength of 215 nm and a resolution of 1&#39; x 1.5&#39;. These are the first wide-field ultraviolet polarimetric images in astronomy. We find the UV background light of the LMC to be linearly polarized at leve

Beth A. Brown, Joel N. Bregman

In order to help understand the phenomena of X-ray emission from early-type galaxies, we obtained an optically flux-limited sample of 34 early-type galaxies, observed with ROSAT. A previous analysis of this sample suggested that the most X-ray luminous galaxies were in rich environments. Here we investigate environmental influences quantitatively, and find a

Richard A. Battye, Martin Bucher, David Spergel

We consider a cosmogony with a dark matter component consisting of a network of frustrated domain walls. Such a network provides a solid dark matter component with $p=-(2/3)ρ$ that remains unclustered on small scales and with $Ω_{\rm dw}\approx 0.7$ can reconcile a spatially flat universe with the many observations indicating $Ω_{\rm m}\approx 0.3.$ Because

S. Dos Santos, G. A. Mamon

We reanalyze the ROSAT PSPC X-ray spectro-photometric observations of HCG 16. Its X-ray morphology resembles its morphology at 20 cm, seen by the NVSS. We detect diffuse emission in 8 regions filling half of the 200/h50 kpc (8.7&#34;) radius circle around the optical center of the group: one encompassing galaxies a&b, two surrounding galaxies c&d, a clumpy r

F. Hussain, J. G. Koerner, Salam Tawfiq

Single pion transitions of S wave to S wave, P wave to S wave and P wave to P wave heavy baryons are analyzed in the framework of the Heavy Quark Symmetry limit (HQS). We use a constituent quark model picture for the light diquark system with an underlying SU(2N_{f}) X O(3) symmetry to reduce the number of the HQS coupling factors required to describe these

G. E. Brown, C. -H. Lee, H. A. Bethe

In this note we study the accretion disc that arises in hypercritical accretion of $\dot M\sim 10^8 M_{\rm Edd}$ onto a neutron star while it is in common envelope evolution with a massive companion. In order to raise the temperature high enough that the disc might cool by neutrino emission, Chevalier found a small value of the $α$-parameter, where the kinem

Jordi Miralda-Escude

The Lyman alpha absorption from intergalactic, once-ionized helium (HeII) has been measured with HST in four quasars over the last few years, over the redshift range 2.4 < z < 3.2. These observations have indicated that the HeII reionization may not have been completed until z\simeq 2.8, and that large fluctuations in the intensity of the HeII-ionizing backg

Nobuyuki Sakai, Ken-ichi Nakao, Tomohiro Harada

We clarify the causal structure of an inflating magnetic monopole. The spacetime diagram shows explicitly that this model is free from ``graceful exit&#39;&#39; problem, while the monopole itself undergoes ``eternal inflation&#39;&#39;. We also discuss general nature of inflationary spacetimes.

Cheng-Wei Chiang

Improved model independent upper bounds on the weak transition form factors are derived using inclusive sum rules. Comparison of the new bounds with the old ones is made for the form factors h_{A_1} and h_V in B -> D* decays.

Leonardo Castellani

Gravity theories are constructed on finite groups G. A self-consistent review of the differential calculi on finite G is given, with some new developments. The example of a bicovariant differential calculus on the nonabelian finite group S_3 is treated in detail, and used to build a gravity-like field theory on S_3.

A. Fontana, N. Menci, S. D&#39;Odorico, E. Giallongo

A combination of ground-based (NTT and VLT) and HST (HDF-N and HDF-S) public imaging surveys have been used to collect a sample of 1712 I-selected and 319 $K\leq 21$ galaxies. Photometric redshifts have been obtained for all these galaxies. The results have been compared with the prediction of an analytic rendition of the current CDM hierarchical models for

Dung-Hai Lee

Starting from the d-wave RVB mean-field theory of Kotliar and Liu, we present a new, long-wavelength/low-energy exact, treatment of gauge fluctuations. The result is a theory of gapless fermion quasiparticles coupled to superconducting phase fluctuations. We will discuss the physical implications, and the similarity/differences with a theory of BCS pairing w

O. A. Aktsipetrov, T. V. Misuryaev, T. V. Murzina, L. M. Blinov

Optical second harmonic generation (SHG) is used as a noninvasive probe of two-dimensional (2D) ferroelectricity in Langmuir-Blodgett (LB) films of copolymer vinylidene fluoride with trifluorethylene. The surface 2D ferroelectric-paraelectric phase transition in the topmost layer of LB films and a thickness independent (almost 2D) transition in the bulk of t

Debabrata Biswas

Periodic orbits are the central ingredients of modern semiclassical theories and corrections to these are generally non-classical in origin. We show here that for the class of generic polygonal billiards, the corrections are predominantly classical in origin owing to the contributions from closed almost-periodic (CAP) orbit families. Furthermore, CAP orbit f

Jan-e Alam, Sourav Sarkar, Pradip Roy, T. Hatsuda

The formulation of the real and virtual photon production rate from strongly interacting matter is presented in the framework of finite temperature field theory. The changes in the hadronic spectral function induced by temperature are discussed within the ambit of the Walecka type model, gauged linear and non-linear sigma models, hidden local symmetry approa

Valery Koryukin

One of the fundamental problems of the theoretical physics is the search of the axioms, which ought to be the basis for the one-valued construction of Lagrangians of the relativistic fields. The creation of the gauge fields theory was the great success in the solution of this problem. The gauge formalism allowed to derive the total Lagrangians of the interac

Hungchong Kim, Takumi Doi, Makoto Oka, Su Houng Lee

Motivated by the recent work on the calculation of the $πNN$ coupling constant using QCD sum rule beyond the chiral limit, we construct the corresponding sum rules for the couplings, $ηNN$, $πΞΞ$, $ηΞΞ$, $πΣΣ$ and $ηΣΣ$. In constructing the $η$-baryon sum rules, we use the second moment of the $η$ wave function, which we obtain from the pion wave function af

Jiro Hashiba, Seiji Terashima

We find the Seiberg-Witten geometry for four dimensional N=2 supersymmetric E_6 gauge theories with massless fundamental hypermultiplets, by geometrically embedding them in type II string theories compactified on Calabi-Yau threefolds. The resulting geometry completely agrees with that of recent works, which are based on the technique of N=1 confining phase