November 1998 arXiv papers — page 21

Sungchul Kwon, WonMuk Hwang, Hyunggyu Park

We study the dynamics of an interface (active domain) between different absorbing regions in models with two absorbing states in one dimension; probabilistic cellular automata models and interacting monomer-dimer models. These models exhibit a continuous transition from an active phase into an absorbing phase, which belongs to the directed Ising (DI) univers

A. Hosseini, R. Harris, Saeid Kamal, P. Dosanjh

We present here the microwave surface impedance of a high purity crystal of $YBa_2Cu_3O_{6.99}$ measured at 5 frequencies between 1 and 75 GHz. This data set reveals the main features of the conductivity spectrum of the thermally excited quasiparticles in the superconducting state. Below 20 K there is a regime of extremely long quasiparticle lifetimes, due t

S. Raymond, T. Yokoo, A. Zheludev, S. E. Nagler

Polarized and unpolarized inelastic neutron scattering is used to study Haldane-gap excitations in the mixed-spin linear-chain antiferromagnet Nd2BaNiO5. The longitudinal mode, polarized along the direction of ordered moments, is observed for the first time. The model of isolated Haldane chains in a static staggered exchange field, that is known to work very

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

We provide a proof that when there is no forcing the recently introduced projective dynamics Monte Carlo algorithm gives the exact lifetime of the metastable state, within statistical uncertainties. We also show numerical evidence illustrating that for slow forcing the approach to the zero-forcing limit is rather rapid. The model studied numerically is the 3

Yu. E. Lozovik, S. A. Verzakov, M. Willander

The superfluidity and Bose-Einstein condensation of indirect excitons in two-dimensional quantum dot are studied by path-integral Monte Carlo simulations. The temperature dependence of superfluid and bose-condensed fraction are calculated at different strengths of interaction. Using the Kosterlitz-Thouless recursion relations, we also predict behavior of sup

Yshai Avishai, Dani Berend, Richard Berkovits

Motivated by recent experiments on large quantum dots, we consider the energy spectrum in a system consisting of $N$ particles distributed among $K<N$ independent sub-systems, such that the energy of each sub-system is a quadratic function of the number of particles residing on it. On a large scale, the ground state energy E(N) of such a system grows quadrat

Alexander P. Dmitriev, Igor V. Gornyi, Valentin Yu. Kachorovskii

We study quantum corrections to conductivity in a 2D system with a smooth random potential and strong spin-orbit splitting of the spectrum. We show that the interference correction is positive and down to the very low temperature can exceed the negative correction related to electron-electron interactions. We discuss this result in the context of the problem

Giorgio Bertotti, Vittorio Basso, Alessandro Magni

The conditions under which relaxation dynamics in the presence of quenched-in disorder lead to rate-independent hysteresis are discussed. The calculation of average hysteresis branches is reduced to the solution of the level-crossing problem for the stochastic field describing quenched-in disorder. Closed analytical solutions are derived for the case where t

A. Barrat, R. Zecchina

We study analytically and numerically the statics and the off-equilibrium dynamics of spin models over finitely connected random graphs. We identify a threshold value for the connectivity beyond which the loop structure of the graph becomes thermodynamically relevant. Glauber dynamics simulations show that this loop structure is responsible for the onset of

Esteban Moro, Grant Lythe

A dynamic symmetry-breaking transition with noise and inertia is analyzed. Exact solution of the linearized equation that describes the critical region allows precise calculation (exponent and prefactor) of the number of defects produced as a function of the rate of increase of the critical parameter. The procedure is valid in both the overdamped and underda

Carlos Mejia-Monasterio, Jean Richert, Thomas Rupp, Hans A. Weidenmueller

Motivated by an experiment by Sivan et al. (Europhys. Lett. 25, 605 (1994)) and by subsequent theoretical work on localization in Fock space, we study numerically a hierarchical model for a finite many-body system of Fermions moving in a disordered potential and coupled by a two-body interaction. We focus attention on the low-lying states close to the Fermi

Zheng Weihong, C. J. Hamer, J. Oitmaa

We use a variety of series expansion methods at both zero and finite temperature to study an antiferromagnetic Heisenberg spin model proposed recently by Miyahara and Ueda for the quasi two-dimensional material SrCu$_2$(BO$_3$)$_2$. We confirm that this model exhibits a first-order quantum phase transition at T=0 between a gapped dimer phase and a gapless Né

T. Saikawa, A. Ferraz

We have studied the pseudogap formation in the single-particle spectra of the half-filling two-dimensional Hubbard model. Using a Green&#39;s function with the one-loop self-energy correction of the spin and charge fluctuations, we have numerically calculated the self-energy, the spectral function, and the density of states in the weak-coupling regime at fin

Krzysztof Kacperski, Janusz A. Holyst

It is common that the average length of chaotic transients appearing as a consequence of crises in dynamical systems obeys a power low of scaling with the distance from the crisis point. It is, however, only a rough trend; in some cases considerable oscillations can be superimposed on it. In this letter we report anomalous oscillations due to the intertwined

Sergei Nayakshin

Rapid progress in multi-wavelength observations of Seyfert Galaxies in recent years is providing evidence that X-ray emission in these objects may be produced by magnetic flares occurring above a cold accretion disk. Here we attempt to develop a physically consistent model of accretion disks producing radiation via magnetic flares as well as the optically th

David L. Block, Ivanio Puerari

(abridged): To derive a coherent physical framework for the excitation of spiral structure in galaxies, one must consider the co-existence of two different dynamical components: a gas-dominated Population I disk (OB associations, HII regions, cold interstellar HI gas) and an evolved stellar Population II component. The Hubble classification scheme has as its

Sergei Nayakshin, James B. Dove

The spectrum of Seyfert 1 Galaxies is very similar to that of several Galactic Black Hole Candidates (GBHCs) in their hard state, suggestive that both classes of objects have similar physical processes. While it appears that an accretion disk corona (ADC) model, where the corona sandwiches the cold accretion disk, is capable of explaining the observations of

Barbara S. Ryden

For a sample of 22 core ellipticals and 22 power law ellipticals, I examine the apparent axis ratios of isophotes as a function of the dynamical time at the isophote&#39;s mean radius. The two types of elliptical galaxy have a significantly different distribution of shapes in the region where the dynamical time is short (about 1 Myr); the core galaxies are r

John F. Hawley, Steven A. Balbus, Wayne F. Winters

We employ a variety of numerical simulations in the local shearing box system to investigate in greater depth the local hydrodynamic stability of Keplerian differential rotation. In particular we explore the relationship of Keplerian shear to the nonlinear instabilities known to exist in simple Cartesian shear. The Coriolis force is the source of linear stab

Ralph A. M. J. Wijers, J. E. Pringle

Precessing accretion discs have long been suggested as explanations for the long periods observed in a variety of X-ray binaries, most notably Her X-1/HZ Her. We show that an instability of the disc&#39;s response to the radiation reaction force from the illumination by the central source can cause the disc to tilt out of the orbital plane and precess in som

A. M. N. Ferguson, R. F. G. Wyse, J. S. Gallagher

The extreme outer regions of disk galaxies, lying at or beyond the classical optical radius defined by R25, present an opportunity to study star formation and chemical evolution under unique physical conditions, possibly reminscent of those which existed during the early stages of disk evolution. We present here some of the first results from a large study t

N. Aghanim, F. -X. Désert, J. -L. Puget, R. Gispert

The y axis of figure 9, which gives the power amplitude ($l(l+1)C_l$) in units of $10^{-12}$, is incorrectly reported. The correct values are obtained by dividing the amplitudes by 16. All the relative values remain valid, and this therefore does not change the conclusions of the paper.

Giorgio Matt

BeppoSAX results on Seyfert galaxies are reviewed and discussed.

N. Wex, S. Kopeikin

For radio pulsars in orbit with a compact companion, pulsar timing observations have proved to be a powerful tool for identifying the physical nature of the companion. Unfortunately, perhaps the most intriguing system where such a tool could be used, a pulsar in orbit with a black hole, has yet to be discovered. In this paper we give a detailed investigation

F. P. Israel

This review summarizes the state of the knowledge of the nearby (D = 3.4 Mpc) radio source Centaurus A and its host galaxy NGC 5128. The massive elliptical host galaxy appears to be moderately triaxial. It contains a strongly warped thin disk, rich in gas, dust and young stars, and roughly aligned with the minor axis of the elliptical galaxy. This and other

J. Heidt, K. Nilsson, A. Sillanpaeae, L. O. Takalo

High-resolution images of 7 newly identified BL Lac objects (among them one BL Lac candidate) at z < 0.2 from the Einstein Slew Survey are presented for the first time. In all cases we were able to resolve the host galaxy. Our 2-dimensional analysis of the host galaxies shows that all these BL Lac objects are embedded in elliptical galaxies with an average M

Stefanie Komossa

Warm absorbers are an important new probe of the central regions of active galaxies. So far, they revealed their existence mainly in the soft X-ray spectral region. In observing and modeling this component, we can learn a lot about the nature of the warm absorber itself, its relation to other components of the active nucleus, and the intrinsic AGN X-ray spec

A. Heller, E. Almoznino, N. Brosch

We analyze the star formation activity of an homogeneous LSB dwarf galaxy sample in the Virgo cluster, as a function of the radial velocity relative to the cluster mean velocity and the projected distance from the center of the cluster, using CCD images obtained at the Wise Observatory. The localized H$α$ emission in the HII regions of this sample is compare

M. L. McCollough, C. R. Robinson, S. N. Zhang, B. A. Harmon

Cyg X-3 is an unusual X-ray binary which shows remarkable correlative behavior between the hard X-ray, soft X-ray, and the radio. We present an analysis of these long term light curves in the context of spectral changes of the system. This analysis will also incorporate a set of pointed RXTE observations made during a period when Cyg X-3 made a transition fr

Ue-Li Pen

Using the cosmic virial theorem, Press-Schechter analysis and numerical simulations, we compute the expected X-ray background (XRB) from the diffuse IGM with the clumping factor expected from gravitational shock heating. The predicted fluxes and temperatures are excluded from the observed XRB. The predicted clumping can be reduced by entropy injection. The r

P. Myers, A. Lazarian

We propose that inward, subsonic flows arise from the local dissipation of turbulent motions in molecular clouds. Such &#34;turbulent cooling flows&#34; may account for recent observations of spatially extended inward motions towards dense cores. These pressure-driven flows may arise from various types of turbulence and dissipation mechanisms. For the exampl

Lazarian A

I review my work with Bruce Draine on dust emissivity at microwave frequencies (3 cm - 3 mm). This emissivity explains the recently detected &#34;anomalous&#34; component of the galactic foreground emission. Both small (a<0.001 micron) and large grains contribute to this emission. Small grains have electric dipole moments and emit while they rotate; the micr

Lazarian A

This paper gives a short summary of a mechanism of the enhanced paramagnetic relaxation that acts on rapidly rotating interstellar grains. We show that the Barnett magnetization that arises from grain rotation ensures that paramagnetic absorption happens at its maximum efficiency, i.e. the conditions for paramagnetic resonance are automatically fulfilled. Th

A. Lazarian, M. Efroimsky

Motivated by a recent study by Lazarian and Draine, which showed that a high degree of grain alignment of the paramagnetic dust is achievable if the rates of internal relaxation are controlled by the Barnett relaxation process, we undertake a study of an alternative mechanism of internal dissipation, namely, the inelastic dissipation of energy in oblate dust

Lazarian A

Grain alignment theory suggests that grains should be aligned in circumstellar regions and the observational data available supports this conclusion. We discuss the alignment of grains via (1) magnetic relaxation, (2) mechanical processes, and (3) radiative torques. We show that ferromagnetic relaxation is likely to be more important than superparamagnetic r

K. A. Misselt, Geoffrey C. Clayton, Karl D. Gordon

We have reanalyzed the Large Magellanic Cloud&#39;s (LMC) ultraviolet (UV) extinction using data from the IUE final archive. Our new analysis takes advantage of the improved signal--to--noise of the IUE NEWSIPS reduction, the exclusion of stars with very low reddening, the careful selection of well matched comparison stars, and an analysis of the effects of

Charles Nelson, Mark Whittle

We have measured the strengths of Ca II Triplet and Mgb stellar absorption lines in the nuclear and off-nuclear spectra of Seyfert galaxies. These features are diluted to varying degrees by continuum emission from the active nucleus and from young stars. Ca II Triplet strengths can be enhanced if late-type supergiant stars dominate the near-IR light. Thus, o

David Eichler, Zakir F. Seidov

It is hypotesized that neutrinos are massles and mixed among three (muon, electron and tau) flavors with a mixing length proportional to (E_nu/E_Planck)^-2. It is suggested that this hypothesis mostly reconciles the standard solar models with the observations of the solar Boron and pp neutrinos, and the atmospheric muon-to-electron neutrinos ratio.

N. D. Lambert, P. C. West

We study the BPS states of the M-fivebrane which correspond to monopoles of N=2 SU(2) gauge theory. Far away from the centres of the monopoles these states may be viewed as solitons in the Seiberg-Witten effective action. It is argued that these solutions are smooth and some properties of their moduli space are discussed.

Ph. de Forcrand

When sampling the distribution P(phi) ~ exp(-|A phi|^2), a global heatbath normally proceeds by solving the linear system A phi = eta, where eta is a normal Gaussian vector, exactly. This paper shows how to preserve the distribution P(phi) while solving the linear system with arbitrarily low accuracy. Generalizations are presented.

Jerome P. Gauntlett, Neil D. Lambert, Peter C. West

We study the conditions for the fivebrane worldvolume theory in D=11 to admit supersymmetric solitons with non-vanishing self-dual three-form. We construct some new soliton solutions consisting of ``superpositions&#39;&#39; of calibrated surfaces, self-dual strings and instantons.

Igor Bandos, Jerzy Lukierski

We consider firstly simple D=4 superalgebra with six real tensorial central charges $Z_{μν}$, and discuss its possible realizations in massive and massless cases. Massless case is dynamically realized by generalized Ferber-Shirafuji (FS) model with fundamental bosonic spinor coordinates. The Lorentz invariance is not broken due to the realization of central

The Jefferson Lab E94014 collaboration, C. S. Armstrong

The differential cross section for the process p(e,e&#39;p)eta has been measured at Q^2 = 2.4 and 3.6 (GeV/c)^2 at center-of-mass energies encompassing the S11(1535) resonance. The latter point is the highest-Q^2 exclusive measurement of this process to date. The resonance width and the helicity-1/2 transition amplitude are extracted from the data, and evide

C. M. Hull

The massive IIA string theory whose low energy limit is the massive supergravity theory constructed by Romans is obtained from M-theory compactified on a 2-torus bundle over a circle in a limit in which the volume of the bundle shrinks to zero. The massive string theories in 9-dimensions given by Scherk-Schwarz reduction of IIB string theory are interpreted

K. V. Tabunshchyk

We present the Hamilton-Jakobi method for the classical mechanics with constrains in Grassmann algebra. In the frame of this method the solution for the classical system characterized by the SUSY Lagrangian is obtained.

Ivo Eschrich

The charge radii of Sigma^- and pi^- have been determined by direct elastic scttering on shell electrons. The measurement was performed in the framework of the SELEX (E781) charm hadroproduction experiment at Fermilab which employs a 600 GeV/c high-intensity Sigma^-/pi^- beam and a 3-stage magnetic spectrometer covering 0.1 <= x_F <= 1.0. Scattering angles a

David A. Lowe, Rikard von Unge

Following the work of Dine and Seiberg for SU(2), we study the leading irrelevant operators on the moduli space of N=4 supersymmetric SU(N) gauge theory. These operators are argued to be one-loop exact, and are explicitly computed.

Yu. A. Golubkov

Using a statistical approach in the framework of non-covariant perturbation theory the distributions for light and charmed quarks in the hadron have been derived, taking into account the mass of the charmed quark. The parameters of the model have been extracted from the comparison with NA3 data on hadroproduction of J/psi particles. A reanalysis of the EMC d

Sergei M. Kopeikin, Gerhard Schafer, Carl R. Gwinn, T. Marshall Eubanks

A consistent approach for an exhaustive solution of the problem of propagation of light rays in the field of gravitational waves emitted by a localized source of gravitational radiation is developed in the first post-Minkowskian and quadrupole approximation of General Relativity. We demonstrate that the equations of light propagation in the retarded gravitat

V. Filinov, Yu. Lozovik, A. Filinov, I. Zacharov

In the second part of this paper in micro canonical ensemble the new numerical approach for consideration of quantum dynamics and calculations of the average values of quantum operators and time correlation functions in the Wigner representation of quantum statistical mechanics has been developed. The numerical results have been obtained for series of the av

Xue-Lei Wang, Yu-Ping Kuang, Hong-yi Zhou, Hua Wang

We study the single top quark production process in various kinds of technicolor models in high energy positron photon collisions at the future electron positron linear colliders. It is shown that if there is certain charged pseudo Goldstone boson (PGB) coupling to t(anti-b), the t(anti-b)-channel PGB contribution is dominant, but the situation is quite diff

D. Eichler

The hypothesis is considered that the vacuum is a Lorentz non-invariant foam in which translational symmetry is spontaneously broken at the Planck or grand unification scale. This could possibly be observed via Rayleigh scattering of ultrahigh energy quanta, and it appears to be ruled out for spin 1/2 leptons and independently testable for photons. A weaker

M. B. Plenio, S. F. Huelga, A. Beige, P. L. Knight

We discuss the generation of entangled states of two two-level atoms inside an optical resonator. When the cavity decay is continuously monitored, the absence of photon-counts is associated with the presence of an atomic entangled state. In addition to being conceptually simple, this scheme could be demonstrated with presently available technology. We descri

Christoph Lamm, Daniel Obermeyer

We define cylinder knots as billiard knots in a cylinder. We present a necessary condition for cylinder knots: after dividing cylinder knots by possible rotational symmetries we obtain ribbon knots. We obtain an upper bound for the number of cylinder knots with two fixed parameters (out of three). In addition we prove that rosette knots are cylinder knots.

M. Bianchi, E. Gava, J. F. Morales, K. S. Narain

We determine the spectrum of D-string bound states in various classes of generalized type I vacuum configurations with sixteen and eight supercharges. The precise matching of the BPS spectra confirms the duality between unconventional type IIB orientifolds with quantized NS-NS antisymmetric tensor and heterotic CHL models in D=8. A similar analysis puts the

Andreas Albrecht, Joao Magueijo

We consider the cosmological implications of light travelling faster in the early Universe. We propose a prescription for deriving corrections to the cosmological evolution equations while the speed of light $c$ is changing. We then show how the horizon, flatness, and cosmological constant problems may be solved. We also study cosmological perturbations in t

M. Nishida, S. Kurihara

The quantum nucleation of phase slips in neutral superfluids confined in a thin torus is investigated by means of the collective coordinate method. We have devised, with numerical justification, a certain collective coordinate to describe the quantum nucleation process of a phase slip. Considering the quantum fluctuation around the local minimum of the actio

Shibaji Banerjee, Sanjay K. Ghosh, Sibaji Raha, Debapriyo Syam

A new dynamical model for the propagation of strangelets through the terrestrial atmosphere is proposed.

Guey-Lin Lin, Tzu-Kang Chyi

We introduce the Vilkovisky-DeWitt formalism for deriving the lower bound of the Higgs boson mass. We illustrate the formalism with a simplified version of the Standard Electroweak Model, where all charged boson fields as well as the bottom-quark field are disregarded. The effective potential obtained in this approach is gauge independent. We derive from the

Changhyun Ahn, Hoil Kim, Bum-Hoon Lee, Hyun Seok Yang

We study M theory on $AdS_4 \times \RP^7$ corresponding to 3 dimensional ${\cal N}=8$ superconformal field theory which is the strong coupling limit of 3 dimensional super Yang-Mills theory. For SU(N) theory, a wrapped M5 brane on $\RP^5$ can be interpreted as baryon vertex. For $SO(N)/Sp(2N)$ theory, by using the property of (co-)homology of $\RP^7$, we cla

A. Ardekani, A. G. Williams

We study the $λϕ^4_{1+1}$ kink solion and the zero-mode contribution to the Kink soliton mass in regions beyond the semiclassical regime. The calculations are done in the non-trivial scaling region and where appropriate the results are compared with the continuum, semiclassical values. We show, as a function of parameter space, where the zero-mode contributi

A. Voros

An exact WKB treatment of 1-d homogeneous Schrödinger operators (with the confining potentials $q^N$, $N$ even) is extended to odd degrees $N$. The resulting formalism is first illustrated theoretically and numerically upon the spectrum of the cubic oscillator (potential $|q|^3$). Concerning the linear potential (N=1), the theory exhibits a duality in which

S. S. Gershtein, V. V. Kiselev, A. K. Likhoded, A. I. Onishchenko

Spectra of masses are calculated for the families of doubly heavy baryons in the framework of nonrelativistic quark model with the QCD potential by Buchmuller--Tye. We suppose the quark-diquark structure for the wave functions and take into account the spin-dependent splittings. The physical reasons causing the existence of quazi-stable excited states in the

Rafael Brada, Mordehai Milgrom

General analytic arguments lead us to expect that in the modified dynamics (MOND) self-gravitating disks are more stable than their like in Newtonian dynamics. We study this question numerically, using a particle-mesh code based on a multi-grid solver for the (nonlinear) MOND field equation. We start with equilibrium distribution functions for MOND disk mode

Dongsu Bak, Soo-Jong Rey

String cosmology is revisited from cosmological viewpoint of holographic principle put forward by `t Hooft, and by Fischler and Susskind. It is shown that the holography requires existence of a `graceful exit&#39; mechanism, which renders the Universe nonsingular by connecting pre- and post-big bang phases smoothly. It is proven that flat Universe is consist

M. Akiyama, K. Ohta, T. Yamada, Y. Ueda

We present results of optical identification of the ASCA Large Sky Survey. X-ray sources which have hard X-ray spectra were identified with type-2 AGN at redshifts smaller than 0.5. It is supported that the absorbed X-ray spectrum of type-2 AGN makes the Cosmic X-ray Background harder in the hard X-ray band than type-1 AGN, which is main contributer in the s

Pijushpani Bhattacharjee, Guenter Sigl

Cosmic ray particles with energies in excess of 10**(20) eV have been detected. The sources as well as the physical mechanism(s) responsible for endowing cosmic ray particles with such enormous energies are unknown. This report gives a review of the physics and astrophysics associated with the questions of origin and propagation of these Extremely High Energ

Subhash Kak

This note presents a few observations on the nonlocal nature of quantum errors and the expected performance of the recently proposed quantum error-correction codes that are based on the assumption that the errors are either bit-flip or phase-flip or both.

Ryszard Horodecki, Michal Horodecki, Pawel Horodecki

We claim that the nonlocality without entanglement revealed quite recently by Bennett {\it et al.} [quant-ph/9804053] should be rather interpreted as {\it Einstein-Podolsky-Rosen paradox without entanglement}. It would be true nonlocality without entanglement if one knew that quantum mechnics provides the best possible means for extracting information from p

Tien D. Kieu, Michael Danos

The halting of universal quantum computers is shown to be incompatible with the constraint of unitarity of the dynamics.

U. V. Toussaint, K. Krieger, R. Fischer, V. Dose

An adaptive kernel method in the Bayesian framework together with a new simulation program for Rutherford backscattering spectroscopy (RBS) have been applied to the analysis of RBS data. Even in the case of strongly overlapping RBS peaks a depth profile reconstruction without noise fitting has been achieved. The adaptive kernel method leads to the simplest d

Myung Ki Cheoun, K. S. Kim, Il-Tong Cheon

We discussed the possibility that the charged axial currents of matter fields could be non-conserved in electromagnetic interaction at $O(e) $ order. It means that chiral symmetry is broken explicitly by electromagnetic interaction. This explicit symmetry breaking of chiral symmetry is shown to lead the mass differences between the charged and neutral partic

F. Kleefeld, M. Dillig

We present some details of our recent theoretical investigations on the total cross section of the reactions $pp\to pp π^0$, $pp\to pp η$ and $pp\to pΛK^+$ at threshold. Applying standard nonrelativistic perturbation theory within the framework of meson exchange models (MEC) to all of the investigated processes we observe that theory is still far--off from a

D. Miskowiec

Asymmetric peaks in the pion-proton correlation functions were observed. Such an asymmetry indicates a displacement between the sources of the two particle species.

Andreas U. Schmidt

I want to point out the mathematical difficulties that arise in the study of the relation of Wightman and Euclidean quantum field theory, i.e., the relation between the hierarchies of Wightman and Schwinger functions. The two extreme cases where the reconstructed Wightman functions are either tempered distributions - the well-known Osterwalder-Schrader recon

Indranil Biswas, Subhashis Nag

To any compact hyperbolic Riemann surface $X$, we associate a new type of automorphism group -- called its *commensurability automorphism group*, $ComAut(X)$. The members of $ComAut(X)$ arise from closed circuits, starting and ending at $X$, where the edges represent holomorphic covering maps amongst compact connected Riemann surfaces (and the vertices repre

Shigetaka Fukuda

Let $X$ be a complete algebraic variety over {\bf C}. We consider a log variety $(X,Δ)$ that is weakly Kawamata log terminal. We assume that $K_X+Δ$ is a {\bf Q}-Cartier {\bf Q}-divisor and that every irreducible component of $\lfloor Δ\rfloor$ is {\bf Q}-Cartier. A nef and big Cartier divisor $H$ on $X$ is called {\it nef and log big} on $(X,Δ)$ if $H |_B$

A. K. Aringazin, K. M. Aringazin, S. Baskoutas, G. Brodimas

Relation between Bopp-Kubo formulation and Weyl-Wigner-Moyal symbol calculus, and non-commutative geometry interpretation of the phase space representation of quantum mechanics are studied. Harmonic oscillator in phase space via creation and annihilation operators, both the usual and $q$-deformed, is investigated. We found that the Bopp-Kubo formulation is j

A. K. Aringazin, V. V. Arkhipov, A. S. Kudusov

BRST formulation of cohomological Hamiltonian mechanics is presented. In the path integral approach, we use the BRST gauge fixing procedure for the partition function with trivial underlying Lagrangian to fix symplectic diffeomorphism invariance. Resulting Lagrangian is BRST and anti-BRST exact and the Liouvillian of classical mechanics is reproduced in the

C. Becchi, S. Giusto, C. Imbimbo

We discuss the formal structure of a functional measure for Gauge Theories preserving the Slavnov-Taylor identity in the presence of Gribov horizons. Our construction defines a gauge-fixed measure in the framework of the lattice regularization by dividing the configuration space into patches with different gauge-fixing prescriptions. Taking into account the

I. V. Kanatchikov

Polymomentum canonical theories, which are manifestly covariant multi-parameter generalizations of the Hamiltonian formalism to field theory, are considered as a possible basis of quantization. We arrive at a multi-parameter hypercomplex generalization of quantum mechanics to field theory in which the algebra of complex numbers and a time parameter are repla

M. Bordag, K. Kirsten, D. Vassilevich

We analyse the ultraviolet divergencies in the ground state energy for a penetrable sphere and a dielectric ball. We argue that for massless fields subtraction of the ``empty space&#39;&#39; or the ``unbounded medium&#39;&#39; contribution is not enough to make the ground state energy finite whenever the heat kernel coefficient $a_2$ is not zero. It turns ou

A. V. Galajinsky, D. M. Gitman

By rigorous application of the Hamiltonian methods we show that the ABC-formulation of the Siegel superparticle admits consistent minimal coupling to external supergravity. The consistency check proves to involve all the supergravity constraints.

Biswarup Mukhopadhyaya, Soumitra Sengupta

In a space-time with torsion, the action for the gravitational field can be extended with a parity-violating piece. We show how to obtain such a piece from geometry itself, by suitably modifying the affine connection so as to include a pseudo-tensorial part. A consistent method is thus suggested for incorporating parity-violation in the Lagrangians of all ma

Oliver Haschke, Werner Ruehl

We construct a quantum mechanical model of the Calogero type for the icosahedral group as the structural group. Exact solvability is proved and the spectrum is derived explicitly.

Amir Masoud Ghezelbash

We consider two different versions of gauged WZW theories with the exceptional groups and gauged with any of theirs null subgroups. By constructing suitable automorphism, we establish the equivalence of these two theories. On the other hand our automorphism, relates the two dual irreducible Riemannian globally symmetric spaces with different characters based

Vadim R. Kudashev, Bulat I. Suleimanov

We construct a one-parametric family of the double-scaling limits in the hermitian matrix model $Φ^6$ for 2D quantum gravity. The known limit of Bresin, Marinari and Parisi belongs to this family. The family is represented by the Gurevich-Pitaevskii solution of the Korteveg-de Vries equation which describes the onset of nondissipative shock waves in media wi

A. V. Radyushkin

We discuss two types of contributions to hadronic form factors in QCD: hard gluon exchange and soft wave function overlap. Within the QCD sum rule approach, the hard contribution has strong numeric suppression by factor (α_s/π) ~ 0.1 for each exchange. For this reason, the soft contribution dominates at accessible momentum transfers. The ``humpy&#39;&#39; di

D. G. Robertson, E. S. Swanson, A. P. Szczepaniak, C. -R. Ji

Extending previous QCD Hamiltonian studies, we present a new renormalization procedure which generates an effective Hamiltonian for the gluon sector. The formulation is in the Coulomb gauge where the QCD Hamiltonian is renormalizable and the Gribov problem can be resolved. We utilize elements of the Glazek and Wilson regularization method but now introduce a

A. V. Radyushkin

The hard exclusive electroproduction processes provide new information about hadronic structure accumulated in nonforward parton distributions. The NFPD&#39;s are universal hybrid functions having the properties of parton densities, hadronic form factors and distribution amplitudes. They give a unified description of various hard exclusive and inclusive reac

Athar Husain

We study the appearance of $ν_τ$ from active galactic nuclei (AGN) through neutrino spin-flip. We consider two situations: i) Spin (flavour)-precession in a reasonable strength of magnetic field in AGN, $B_{AGN}$ ii) Adiabatically resonant conversions caused by an interplay of $B_{AGN}$ and the violation of equivalence principle. Observational consequences f

M. Diehl, T. Gousset, B. Pire

Off-diagonal parton distributions occur in several hard exclusive reactions. They extend the study of hadron structure beyond what can be learned from ordinary distributions and have a particularly rich spin structure. The hard scattering subprocesses in electroproduction of mesons and of real photons satisfy helicity selection rules, which provide powerful

Gregory Mahlon

We discuss the optimal spin bases for describing angular correlations in single top quark events at the Fermilab Tevatron. We define spin bases that exploit the fact that the top quarks are produced with 100% polarization along the momenta of the d-type quarks in these events. For single top production through an s-channel W boson, 98% of the top quarks have

B. L. Ioffe

The correlator of topological charge densities $χ(Q^2)$ in QCD is calculated in the domain of low $Q^2$. Basing on the Ward identities the low energy theorems are proved. The value of the first derivative $χ^{\prime}(0)$ found recently by QCD sum rules \cite{1} is used. The contributions of pseudoscalar quasi-Goldstone bosons as intermediate states in the co

H. Casini, J. C. D'Olivo, R. Montemayor, L. F. Urrutia

In this work we propose an extended formulation for the interaction between neutrinos and gravitational fields. It is based on the parametrized post-Newtonian aproach, and includes a violation of the universality of the gravitational interaction which is non diagonal in the weak flavor space. We find new effects that are not considered in the standard scenar

C. Pajares, Yu. M. Shabelski

We consider the dependences of the average number of interacting nucleons in high energy heavy ion collisions on the impact parameter in two cases, when the colliding nuclei have equal atomic weights, and when one nucleus is significantly more heavy in comparison with the second one. We argue that in the case of trigger of some rare event (say, $J/ψ$, or $Υ$

Yeong Gyun Kim, Pyungwon Ko, Jae Sik Lee, Kang Young Lee

We consider lepton flavor violations (LFV) mediated by photino as a result of the nondiagonal slepton mass matrices in general supersymmetric models. Using the experimental upper bounds on l \to l&#39; + gamma and mu^- + Ti \to e^- + Ti as constraints on the flavor changing slepton mass insertions, we predict the possible ranges of the upper limits on the br

D. Becirevic, Ph. Boucaud, J. P. Leroy, V. Lubicz

We present a study of the heavy-light spectrum and of the D- and B-meson decay constants. The results wer e obtained in the quenched approximation, by using the non-perturbatively improved Clover lattice action at beta=6.2, with a sample of 100 configurations, on a 24^3 x 64 lattice. After a careful analysis of th e systematic errors present in the extractio

Jean E. Duboscq

A limit on the mass of the tau neutrino is derived from 4.5x10^6 tau pairs produced at a center of mass energy of 10.6 GeV. The measurement technique involves a two-dimensional extended likelihood analysis, including the dependence of the end-point population on the tau neutrino mass, and allows for the first time an explicit background contribution. We use

Sascha Husa

We study the utilization of conformal compactification within the conformal approach to solving the constraints of general relativity for asymptotically flat initial data. After a general discussion of the framework, particular attention is paid to simplifications that arise when restricting to a class of initial data which have a certain $U(1)\times U(1)$ c