January 2002 arXiv papers — page 20

J. M. Montanero, V. Garzo

Steady simple shear flow of a low-density binary mixture of inelastic smooth hard spheres is studied in the context of the Boltzmann equation. This equation is solved by using two different and complementary approaches: a Sonine polynomial expansion and the direct simulation Monte Carlo method. The dependence of the shear and normal stresses as well as of th

Henk W. J. Bloete, Wenan Guo, Henk J. Hilhorst

We investigate the two-dimensional classical Heisenberg model with a nonlinear nearest-neighbor interaction V(s,s')=2K[(1+s.s')/2 ]^p. The analogous nonlinear interaction for the XY model was introduced by Domany, Schick, and Swendsen, who find that for large p the Kosterlitz-Thouless transition is preempted by a first-order transition. Here we show

Gerrit Coddens

We refute recent claims that ultrafast atomic jumps as observed in quasicrystals (QC) could be called phasons in many crystalline alloys by pointing out that there is a genuine conceptual difference between the hopping dynamics in an imperfect crystal containing a substantial number of vacancies, and the hopping dynamics due to phason motion in QC.

Zh. S. Gevorkian, Chin-Kun Hu

We study the density-density correlation function of the dense random heteropolymer solutions. We show that a phase transition is possible due to the heterogeneity of polymers. We also show that the critical behavior of the system is described by the O(N) model at N=0.

Hans C. Fogedby

After a brief introduction we review the nonperturbative weak noise approach to the KPZ equation in one dimension. We argue that the strong coupling aspects of the KPZ equation are related to the existence of localized propagating domain walls or solitons representing the growth modes; the statistical weight of the excitations is governed by a dynamical acti

M. Dressel, N. Kasper, K. Petukhov, B. Gorshunov

The optical conductivity of the heavy fermions UPd2Al3 and UPt3 has been measured in the frequency range from 10 GHz to 1.2 THz (0.04 meV to 5 meV) at temperatures 1 K < T < 300 K. In both compounds a well pronounced pseudogap of less than a meV develops in the optical response at low temperatures; we relate this to the antiferromagnetic ordering. From the e

J. A. Hodges, P. Bonville, A. Forget, A. Yaouanc

Using neutron diffraction, 170Yb Mossbauer and muSR spectroscopies, we have examined the pyrochlore Yb2Ti2O7 where the Yb3+ S&#39;=1/2 ground state has planar anisotropy. Below ~0.24K, the temperature of the known specific heat lambda transition, there is no long range magnetic order. We show that the transition corresponds to a first order change in the flu

R. Khasanov, A. Shengelaya, K. Conder, E. Morenzoni

The oxygen-isotope (^16O/^18O) effect (OIE) on the in-plane penetration depth $λ_{ab} (0)$ in underdoped Y_{1-x}Pr_xBa_2Cu_3O_{7-delta} was studied by muon-spin rotation. A pronounced OIE on $λ_{ab}^{-2}(0)$ was observed with a relative isotope shift of $Δλ^{-2}_{ab}/λ^{-2}_{ab}$=-5(2)% for x =0.3 and -9(2)% for x=0.4. It arises mainly from the oxygen-mass d

Stefan Goedecker, Luc Billard, Thierry Deutsch

Due to their technological importance, point defects in silicon are among the best studied physical systems. The experimental examination of point defects buried in bulk is difficult and evidence for the various defects usually indirect. Simulations of defects in silicon have been performed at various levels of sophistication ranging from fast force fields t

K. A. Matveev, A. V. Andreev

We study Coulomb blockade oscillations of thermoelectric coefficients of a single electron transistor based on a quantum dot strongly coupled to one of the leads by a quantum point contact. At temperatures below the charging energy E_C the transport of electrons is dominated by strong inelastic cotunneling. In this regime we find analytic expressions for the

M. Grigorescu, W. E. Baylis

A quasiclassical correspondent for the fermion degrees of freedom is obtained by using a time-dependent variational principle with Grassmann coherent states as trial functions. In the real parametrization provided by the canonical coordinates, these states satisfy a closure relationship, and this is used to calculate the partition function at finite temperat

R. Dodson, K. Golap

The association of G343.1-2.3 and PSR 1706-44 has been controversial from its first proposal. In this paper we address the difficulties, and argue that the association is still likely. New evidence comes from images of G343.1-2.3 obtained using the Australia Telescope Compact Array (ATCA), and the pulsar obtained using the CHANDRA X-ray observatory. Mosaicin

Ariyeh H. Maller, Avishai Dekel

We model in simple terms the angular-momentum problems of galaxy formation in CDM cosmologies, and identify the key elements of a scenario that may solve them. The buildup of angular momentum is modeled via dynamical friction and tidal stripping in a sequence of mergers. We demonstrate how over-cooling in incoming halos leads to a transfer of angular momentu

L. L. Cowie, G. P. Garmire, M. W. Bautz, A. J. Barger

We present the 2-8 keV number counts from the 1Ms Chandra observation of the Chandra Deep Field North (CDF-N). We combine these with the number counts from a 78ks exposure of the Hawaii Survey Field SSA22 and with the number counts obtained in independent analyses of the CDF-S and the Hawaii Survey Field SSA13 to determine the number counts from 2.10^(-16) t

Richard W. Pogge, Paul Martini

We present archival Hubble Space Telescope images of the nuclear regions of 43 of the 46 Seyfert galaxies found in the volume-limited, spectroscopically-complete CfA Redshift Survey sample. Using an improved method of image contrast enhancement, we create detailed high-quality structure maps that allow us to study the distributions of dust, star clusters, an

A. Lenorzer, B. Vandenbussche, P. Morris, A. de Koter

We present an atlas of spectra of O- and B-type stars, obtained with the Short Wavelength Spectrometer (SWS) during the Post-Helium program of the Infrared Space Observatory (ISO). This program is aimed at extending the Morgan & Keenan classification scheme into the near-infrared. Later type stars will be discussed in a seperate publication. The observations

T. M. A. Webb, S. A. Eales, S. J. Lilly, D. L. Clements

We present the complete submillimeter data for the Canada-UK Deep Submillimeter Survey (CUDSS) 3-hour field. The obeservations were taken with the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope on Mauna Kea. The 3-hour field is one of two main fields in our survey and covers 60 square arcminutes to a 3-sigma depth of 3

Takayoshi Sano, James M. Stone

The effect of the Hall term on the evolution of the magnetorotational instability (MRI) in weakly ionized accretion disks is investigated using local axisymmetric simulations. First, we show that the Hall term has important effects on the MRI when the temperature and density in the disk is below a few thousand K and between 10^13 and 10^18 cm^{-3} respective

S. Nishiura, Y. Shioya, T. Murayama, Y. Sato

In order to investigate the properties of the prominent tidal debris feature extending to the northeast of the compact group of galaxies Seyfert&#39;s Sextet, we analyzed multi-band (U, B, V, VR, R, I, J, H and K&#39;) photometric imaging data and obtained the following results: 1) The radial surface brightness distribution of this tidal debris in Seyfert&#3

G. Sonneborn, M. Andre, C. Oliveira, G. Hebrard

High resolution far-ultraviolet spectra of the O-type subdwarf BD +28 4211 were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) to measure the interstellar deuterium, nitrogen, and oxygen abundances in this direction. The interstellar D I transitions are analyzed down to Lyman iota at 920.7 A. The star was observed several times at different

Eric Emsellem

Density waves in the central kpc of galaxies, taking the form of spirals, bars and/or lopsided density distributions, are potential actors of the redistribution of angular momentum. They may thus play an important role in the overall evolution of the central structures, not mentioning the possible link with the active/non-active central mass concentration. I

Didier Fraix-Burnet

It is shown that linear polarization data can be used to constrain the composition (normal or pair plasma) of pc-scale extragalactic jets. A simple criterion, based on synchrotron and Faraday depolarization properties, is established. It does not depend on the particle density and the length of the emitting region along the line of sight, thus eliminating tw

Zoltan Haiman

The first galaxies formed at high redshifts, and were likely substantially less massive than typical galaxies in the local universe. We argue that (1) the reionization of a clumpy intergalactic medium by redshift z=6, (2) its enrichment by metals by z=3 without disturbing the Lyman alpha forest, and (3) the presence of supermassive black holes powering the r

Tomas Dahlen, Ariel Goobar

Deep, ground based, optical wide-field supernova searches are capable of detecting a large number of supernovae over a broad redshift range up to z~1.5. While it is practically unfeasible to obtain spectroscopic redshifts of all the supernova candidates right after the discovery, we show that the magnitudes and colors of the host galaxies, as well as the sup

F. V. Prigara

It was shown recently that thermal radio emission has a stimulated character, and it is quite possible that thermal black body radiation in other spectral ranges also has an induced origin. The induced origin of thermal black body emission leads to important astrophysical consequences, such as the existence of laser type sources and thermal harmonics in stel

N. S. Dzhalilov, J. Staude

The general PDE governing linear, adiabatic, nonraradial oscillations in a spherical, differentially and slowly rotating non-magnetic star is derived. This equation describes mainly low-frequency and high-degree g-modes, convective g-modes, and rotational Rossby-like vorticity modes and their mutual interaction for arbitrarily given radial and latitudinal gr

Jun Yokogawa, Kensuke Imanishi, Katsuji Koyama, Mamiko Nishiuchi

This paper presents ASCA/SIS and ROSAT/HRI results of three supernova remnants (SNRs) in the Small Magellanic Cloud: 0103-726, 0045-734, and 0057-7226. The ROSAT/HRI images of these SNRs indicate that the most of the X-ray emissions are concentrated in the center region. Only from 0103-726 are faint X-rays along the radio shell also detected. The ASCA/SIS sp

J. A. S. Lima, J. A. Espichán Carrillo

We study the thermodynamic behavior of a decaying scalar field coupled to a relativistic simple fluid. It is shown that if the decay products are represented by a thermalized bath, its temperature evolution law requires naturally a new phenomenological coupling term. This ``energy loss&#39;&#39; term is the product between the enthalpy density of the thermal

A. V. Turbiner, J. C. Lopez V., A. Flores-Riveros

In the framework of a variational method with a single trial function an accurate study of the lowest gerade 1g and ungerade 1u electronic states of the molecular ion $H_2^+$ in a magnetic field is performed. Magnetic field ranges from 0 to 4.414x10^13 G and orientations of the molecular axis with respect to the magnetic line 0 \leq theta \leq 90 are conside

Roberto B. Diener, Biao Wu, Mark G. Raizen, Qian Niu

We propose a quantum tweezer for extracting a desired number of neutral atoms from a reservoir. A trapped Bose-Einstein condensate (BEC) is used as the reservoir, taking advantage of its coherent nature, which can guarantee a constant outcome. The tweezer is an attractive quantum dot, which may be generated by red-detuned laser light. By moving with certain

Matthew Ando

We construct a canonical Thom isomorphism in Grojnowski&#39;s equivariant elliptic cohomology, for virtual T-oriented T-equivariant spin bundles with vanishing Borel-equivariant second Chern class, which is natural under pull-back of vector bundles and exponential under Whitney sum. It extends in the complex-analytic case the non-equivariant sigma orientatio

Ernest Ma

In extending the minimal standard model of quarks and leptons to include supersymmetry, the conservation of baryon and lepton numbers is no longer automatic. I show how the latter may be achieved with a new U(1) gauge symmetry and new supermultiplets at the TeV scale. Neutrino masses and a solution of the $μ$ problem are essential features of this proposed e

T. Blazek, R. Dermisek, S. Raby

In simple SO(10) SUSY GUTs the top, bottom and tau Yukawa couplings unify at the GUT scale. A naive renormalization group analysis, neglecting weak scale threshold corrections, leads to moderate agreement with the low energy data. However it is known that intrinsically large threshold corrections proportional to $\tanβ\sim m_t(M_Z)/m_b(M_Z) \sim 50$ can null

M. J. Duff

In 1981, covariantly constant spinors were introduced into Kaluza-Klein theory as a way of counting the number of supersymmetries surviving compactification. These are related to the holonomy group of the compactifying manifold. The first non-trivial example was provided in 1982 by D=11 supergravity on the squashed S7, whose G2 holonomy yields N=1 in D=4. In

Cédric Deffayet, Susana J. Landau, Julien Raux, Matias Zaldarriaga

We discuss observational constraints coming from CMB and type Ia supernovae, for the model of accelerated universe produced by gravitational leakage into extra dimensions. Our fits indicate that the model is currently in agreement with the data. We also give the equations governing the evolution of cosmological perturbations. Future observations will be able

T. Jungwirth, Jürgen König, Jairo Sinova, J. Kučera

We present a theoretical survey of ferromagnetic transition temperatures in cubic (III,Mn)V semiconductors based on a model with $S=5/2$ local moments exchange-coupled to itinerant holes in the host semiconductor valence band. Starting from the simplest mean-field theory of this model, we estimate the $T_c$ enhancement due to exchange and correlation in the

O. Scavenius, A. Dumitru, J. T. Lenaghan

We perform a field-theoretical computation of hadron production in large systems at the QCD confinement phase transition associated with restoration of the Z(3) global symmetry. This occurs from the decay of a condensate for the Polyakov loop. From the effective potential for the Polyakov loop, its mass just below the confinement temperature T_c is in betwee

M. Cencini, A. Torcini, D. Vergni, A. Vulpiani

Front propagation in two dimensional steady and unsteady cellular flows is investigated in the limit of very fast reaction and sharp front, i.e., in the geometrical optics limit. In the steady case, by means of a simplified model, we provide an analytical approximation for the front speed, $v_{\scriptsize{f}}$, as a function of the stirring intensity, $U$, i

Young Deuk Kim

Let B^3 be the closed unit ball in R^3 and S^2 its boundary. We define a family of pseudo metrics on B^3. As an application, We prove that for any countable-to-one function f:S^2\to [0,a], the set NM^n_f={x\in S^2 | there exists y\in S^2 such that f(x)-f(y)>nd_E(x,y)} is uncountable for all natural number n, where d_E is the Euclidean metric on R^3.

E. V. Gotthelf, J. P. Halpern, R. Dodson

We report the first detection of pulsed X-ray emission from the young, energetic radio and Gamma-ray pulsar PSR B1706-44. We find a periodic signal at a frequency of f = 9.7588088 +/- 0.0000026 Hz (at epoch 51585.34104 MJD), consistent with the radio ephemeris, using data obtained with the High Resolution Camera on-board the Chandra X-ray Observatory}. The p

Douglas M. Eardley, Steven B. Giddings

We investigate classical formation of a D-dimensional black hole in a high energy collision of two particles. The existence of an apparent horizon is related to the solution of an unusual boundary-value problem for Poisson&#39;s equation in flat space. For sufficiently small impact parameter, we construct solutions giving such apparent horizons in D=4. These

James F. Davis, Kimberly Pearson

We prove the Gromov-Lawson-Rosenberg conjecture for cocompact Fuchsian groups, thereby giving necessary and sufficient conditions for a closed spin manifold of dimension greater than four with fundamental group cocompact Fuchsian to admit a metric of positive scalar curvature.

Feryal Ozel

We study the pulse morphologies and pulse amplitudes of thermally emitting neutron stars with ultrastrong magnetic fields. The beaming of the radiation emerging from a magnetar was recently shown to be predominantly non-radial, with a small pencil and a broad fan component. We show that the combination of this radiation pattern with the effects of strong len

Ulf-G. Meißner

Recent developments and open issues in chiral dynamics with strange quarks are reviewed. Topics include: Order parameters of chiral symmetry breaking, the flavor dependence of these order parameters, speculations about the phase structure of QCD with varying number of flavors, OZI violation and its natural emergence in case of a small strange quark condensat

M. Anselmino, D. Boer, U. D'Alesio, F. Murgia

A formalism proposed to study transverse Lambda polarization in unpolarized hadronic processes, based on a generalized pQCD factorization theorem, is extended to semi-inclusive DIS. Analytical expressions and examples of numerical estimates are given.

Ruslan Sharipov

Special orthogonal matrices with rational elements form the group SO(n,Q), where Q is the field of rational numbers. A theorem describing the structure of an arbitrary matrix from this group is proved. This theorem yields an algorithm for generating such matrices by means of random number routines.

N. M. R. Peres, M. N. Araujo

We calculate the antiferromagnetic spin wave dispersion in the half-filled Hubbard model for a two-dimensional square lattice and find it to be in excellent agreement with recent high-resolution inelastic neutron scattering performed on La2CuO4 [Phys. Rev. Lett. 86, 5377 (2001)].

M. Steinhauser

In this review some recent multi-loop results obtained in the framework of perturbative Quantum Chromodynamics (QCD) and Quantum Electrodynamics (QED) are discussed. After reviewing the most advanced techniques used for the computation of renormalization group functions, we consider the decoupling of heavy quarks. In particular, an effective method for the e

Ralf Hofmann

Based on the (in part verified) ideas of a dynamical ``abelian-ization&#39;&#39; and subsequent ``center-ization&#39;&#39; of pure SU($N$) gauge theory an effective potential for relevant field variables is constructed in the limit of large N. To do this the theory is assumed to be thermalized and to be gravitationally deformed. BPS saturation in the dynamic

Marek Szydlowski, Mariusz P. Dabrowski, Adam Krawiec

We apply methods of dynamical systems to study the behaviour of the Randall-Sundrum models. We determine evolutionary paths for all possible initial conditions in a 2-dimensional phase space and we investigate the set of accelerated models. The simplicity of our formulation in comparison to some earlier studies is expressed in the following: our dynamical sy

J. Sanchez-Guillen, R. A. Vazquez

A new approach to the quenched propagator in QED beyond the IR limit is proposed. The method is based on evolution equations in the proper time.

Tsampikos Kottos, Doron Cohen

The analysis of dissipation and dephasing in driven mesoscopic devices requires a distinction between two notions of quantum irreversibility. One (&#34;Loschmidt echo&#34;) is related to &#34;time reversal&#34;, while the other is related to &#34;driving reversal&#34;. In the latter context the time of maximum return (compensation) should substitute the inap

Claudia Bauer, Hartmut Wachter

In this article we present explicit formulae for q-differentiation on quantum spaces which could be of particular importance in physics, i.e., q-deformed Minkowski space and q-deformed Euclidean space in three or four dimensions. The calculations are based on the covariant differential calculus of these quantum spaces. Furthermore, our formulae can be regard

K. Anikeev, D. Atwood, F. Azfar, S. Bailey

This report provides a comprehensive overview of the prospects for B physics at the Tevatron. The work was carried out during a series of workshops starting in September 1999. There were four working groups: 1) CP Violation, 2) Rare and Semileptonic Decays, 3) Mixing and Lifetimes, 4) Production, Fragmentation and Spectroscopy. The report also includes intro

Adrian P. Flitney, Joseph Ng, Derek Abbott

Parrondo&#39;s Paradox arises when two losing games are combined to produce a winning one. A history dependent quantum Parrondo game is studied where the rotation operators that represent the toss of a classical biased coin are replaced by general SU(2) operators to transform the game into the quantum domain. In the initial state, a superposition of qubits c

J. A. Smith, D. L. Tucker, S. Kent, M. W. Richmond

We present the 158 standard stars that define the u'g'r'i'z' photometric system. These stars form the basis for the photometric calibration of the Sloan Digital Sky Survey (SDSS). The defining instrument system and filters, the observing process, the reduction techniques, and the software used to create the stellar network are all described. We briefly discu

S. J. Hands, J. B. Kogut, C. G. Strouthos

We present results from a numerical study of bound state wavefunctions in the (2+1)-dimensional Gross-Neveu model with staggered lattice fermions at both zero and nonzero temperature. Mesonic channels with varying quantum numbers are identified and analysed. In the strongly coupled chirally broken phase at T=0 the wavefunctions expose effects due to varying

Wim van Dam, Patrick Hayden

We show that in the presence of arbitrary catalysts, any pure bipartite entangled state can be converted into any other to unlimited accuracy without the use of any communication, quantum or classical.

Marco Frasca

It is shown how classical states, meant as states representing a classical object, can be produced in the thermodynamic limit, retaining the unitary evolution of quantum mechanics. Besides, using a simple model of a single spin interacting with a spin-bath, it is seen how decoherence, with the off-diagonal terms in the density matrix going to zero, can be ob

S. Imre, F. Balazs

3G and 4G mobile are based on CDMA technology. In order to increase the effectiveness of CDMA receivers large amount of effort is invested to develop suitable multi-user detector techniques. However, at this moment there are only suboptimal solutions available because of the rather high complexity of optimal detectors. One of the possible receiver technologi

V. N. Smelyanskiy, U. V. Toussaint, D. A. Timucin

We analyze the complexity of the quantum optimization algorithm based on adiabatic evolution for the set partition problem. We introduce a cost function defined on a logarithmic scale of the partition residues so that the total number of values of the cost function is of the order of the problem size. We simulate the behavior of the algorithm by numerical so

Christophe Boisseau, Ionel Simbotin, Robin Cote

We study long range interactions between two Rydberg atoms and predict the existence of ultralong range Rydberg dimers with equilibrium distances of many thousand Bohr radii. We calculate the dispersion coefficients $C_{5}$, $C_{6}$ and $C_{8}$ for two rubidium atoms in the same excited level $np$, and find that they scale like $n^{8}$, $n^{11}$ and $n^{15}$

E. L. Bolda, E. Tiesinga, P. S. Julienne

We consider the problem of cold atomic collisions in tight traps, where the absolute scattering length may be larger than the trap size. As long as the size of the trap ground state is larger than a characteristic length of the van der Waals potential, the energy eigenvalues can be computed self-consistently from the scattering amplitude for untrapped atoms.

Alexander Fradkov, Anton Krivtsov, Alexander Efimov

New method for dissociation of diatomic molecule based on nonperiodic excitation generated by energy-feedback control mechanism is proposed. The energy-feedback control uses frequency-energy (FE) relation of the natural oscillations to fulfill the resonance conditions at any time of excitation. Efficiency of the proposed method is demonstrated by the problem

Uri Raviv, Jacob Klein, T. A. Witten

Compression of an adsorbed polymer layer distorts its relaxed structure. Surface force measurements from different laboratories show that the return to this relaxed structure after the compression is released can be slowed to the scale of tens of minutes and that the recovery time grows rapidly with molecular weight. We argue that the arrested state of the f

Phoebe Hoidn, Robert B. Kusner, Andrzej Stasiak

Probably the most natural energy functional to be considered for knotted strings is the one given by the electrostatic repulsion. In the absence of counter-charges, a charged, knotted string evolving along the energy gradient of electrostatic repulsion would progressively tighten its knotted domain into a point on a perfectly circular string. However, in the

J. M. Sampaio, K. Langanke, G. Martinez-Pinedo, D. J. Dean

We study the neutral-current neutrino scattering for four nuclei in the iron region. We evaluate the cross sections for the relevant temperatures during the supernova core collapse and derive Gamow-Teller distributions from large-scale shell-model calculations. We show that the thermal population of the excited states significantly enhances the cross section

M. Anguiano, G. Co&#39;, A. M. Lallena, S. R. Mokhtar

One-nucleon emission processes induced by photon absorption are studied by considering short-range correlations effects. At energies above the giant resonance region the validity of the direct knock-out model has been tested by comparison with continuum Random Phase Approximation results. Nucleon re-scattering effects have been considered by using an optical

V. A. Sadovnikova

The solutions to the zero-sound frequency equation and pion dispersion equation are considered for the different values of the parameters of the effective particle-hole interaction. The branches of solutions, responsible for the long-wave instability [Pomeranchuk] of the nuclear matter ω_P(k) are presented for the both equations. It is shown that in the pion

W. Nörenberg, G. Papp, P. Rozmej

Results on dissipative isoscalar modes of a hot and dilute nuclear droplet are presented. As compared to the adiabatic limit (part I), realistic dissipation yields a substantial reduction of the growth rates for all unstable modes, while the area of spinodal instability in the ($\varrho$,T)-plane remains unchanged. The qualitative features of multifragmentat

Sergei Igonin

By the Cole-Hopf transformation, with any linear evolution equation in 1+1 dimensions a generalized Burgers equation is associated. We describe local conservation laws of these equations. It turns out that any generalized Burgers equation has only one conservation law, while a linear evolution equation with constant coefficients has an infinite number of (x,

J. G. B. Byatt-Smith, H. W. Braden

We obtain the general solution of the functional equation introduced by Ruijsenaars guaranteeing the commutativity of n operators associated with the quantum Ruijsenaars-Schneider models.

Y. Chen, T. Grava

In this note we compute the functional derivative of the induced charge density, on a thin conductor, consisting of the union of g+1 disjoint intervals, $J:=\cup_{j=1}^{g+1}(a_j,b_j),$ with respect to an external potential. In the context of random matrix theory this object gives the eigenvalue fluctuations of Hermitian random matrix ensembles where the eige

Tom Hadfield

Motivated by the search for new examples of ``noncommutative manifolds&#39;&#39;, we study the noncommutative geometry (in the sense of Connes) of the group C*-algebras of various discrete groups. The examples we consider are the infinite dihedral group Z \times_σ $Z_2$ and the semidirect product group $Z \times_σ Z$. We present a unified treatment of the K-

Tom Hadfield

Motivated by the search for new examples of ``noncommutative manifolds&#39;&#39;, we study the noncommutative geometry (in the sense of Connes) of the group C*-algebra of the three dimensional discrete Heisenberg group. We present a unified treatment of the K-homology, cyclic cohomology and derivations of this algebra.

Janusz Grabowski, Giuseppe Marmo

Binary operations on algebras of observables are studied in the quantum as well as in the classical case. It is shown that certain natural compatibility conditions with the associative product imply the properties which usually are additionally required. In particular, it is proved that locality of a Loday bracket on sections of a one-dimensional vector bund

Nikolai Nikolov, Peter Pflug

The boundary behavior of the Bergman metric near a convex boundary point $z_0$ of a pseudoconvex domain $D\subset\CC^n$ is studied; it turns out that the Bergman metric at points $z\in D$ in direction of a fixed vector $X_0\in\CC^n$ tends to infinite, when z is approaching $z_0$, if and only if the boundary of D does not contain any analytic disc through $z_

P. Mohanty, S. Madan

In this paper we have characterized the space of summability kernels for the case p=1 and p=2. For other values of p we give a necessary condition for a function $Λ$ to be a summability kernel. For the case p=1, we have studied the properties of measures which are transferred from $M(\mathbb Z)$ to $M(\mathbb R)$ through summability kernels. Further, we have

Alexander Schmitt

In this note, we introduce the notion of a singular principal G-bundle, associated to a reductive algebraic group G over the complex numbers by means of a faithful representation $\varrho^\p\colon G\lra \SL(V)$. This concept is meant to provide an analogon to the notion of a torsion free sheaf as a generalization of the notion of a vector bundle. We will con

P. Mohanty, S. Madan

In this paper we prove that if $Λ\in M_p(\mathbb R^N)$ and has compact support then $Λ$ is a weak summability kernel for $1<p<\infty$, where $M_p(\mathbb R^N)$ is the space of multipliers of $L^p(\mathbb R^N)$.

Jan Snellman

We study a certain poset on the free monoid on a countable alphabet. This poset is determined by the fact that its total extensions are precisely the standard term orders. We also investigate the poset classifying degree-compatible standard term orders, and the poset classifying sorted term orders. For the latter poset, we give a Galois coconnection with the

Jan Snellman

We study the ring of arithmetical functions with unitary convolution, giving an isomorphism to a generalized power series ring on infinitely many variables, similar to the isomorphism of Cashwell-Everett between the ring of arithmetical functions with Dirichlet convolution and the power series ring on countably many variables. We topologize it with respect t

Matthias Neufang

Let G be a locally compact non-compact group. We show that under a very mild assumption on the weight function w, the weighted group algebra L_1(G,w) is strongly Arens irregular in the sense of Dales-Lamb-Lau. To this end, we first derive a general factorization theorem for bounded families in the L_\infty(G,1/w)^*-module L_\infty(G,1/w).

William Gordon Ritter

This is a short, self-contained expository survey, focused on algebraic and analytic aspects of quantum groups. Topics covered include the definition of ``quantum group,&#39;&#39; the Yang-Baxter equation, quantized universal enveloping algebras, representations of braid groups, the KZ equations and the Kohno-Drinfeld theorem, and finally compact quantum gro

Matthias Neufang

Let G be a locally compact group. Consider the Banach algebra L_1(G)^**, equipped with the first Arens multiplication, as well as the algebra LUC(G)^*, the dual of the space of bounded left uniformly continuous functions on G, whose product extends the convolution in the measure algebra M(G). We present (for the most interesting case of a non-compact group)

Matthias Neufang

Let (M,N) be a pair of von Neumann algebras, or of dual operator spaces with at least one of them having property S_σ, and let T be an arbitrary completely bounded mapping on M. We present an explicit construction of an amplification of T to a completely bounded mapping on the w^*-spatial tensor product of M and N. Our approach makes essential use of the des

Adrian Butscher

Let $L$ be a special Lagrangian submanifold of a compact, Calabi-Yau manifold $M$ with boundary lying on the symplectic, codimension 2 submanifold $W$. It is shown how deformations of $L$ which keep the boundary of $L$ confined to $W$ can be described by an elliptic boundary value problem, and two results about minimal Lagrangian submanifolds with boundary a

Biswaranjan Behera

The orthonormal basis generated by a wavelet of $L^2(\mathbb R)$ has poor frequency localization. To overcome this disadvantage Coifman, Meyer, and Wickerhauser constructed wavelet packets. We extend this concept to the higher dimensions where we consider arbitrary dilation matrices. The resulting basis of $L^2({\mathbb R}^d)$ is called the multiwavelet pack

Peter Brinkmann

We present necessary and sufficient conditions for the existence of a splitting over $\mathbb{Z}$ of the mapping torus $M_ϕ=F\rtimes \mathbb{Z}$ of a free group automorphism $ϕ$.

Kurt Haller

We review the procedure by which we implemented the non-Abelian Gauss&#39;s law and constructed gauge-invariant fields for QCD in the temporal (Weyl) gauge. We point out that the operator-valued transformation that transforms gauge-dependent temporal-gauge fields into gauge-invariant ones has the formal structure of a gauge transformation. We express the ``s

V. G. Bagrov, D. M. Gitman, V. B. Tlyachev

We present new exact solutions (in 3+1 and 2+1 dimensions) of relativistic wave equations (Klein-Gordon and Dirac) in external electromagnetic fields of special form. These fields are combinations of Aharonov-Bohm solenoid field and some additional electric and magnetic fields. In particular, as such additional fields, we consider longitudinal electric and m

Igor A. Bandos, Jose A. de Azcarraga, Jose M. Izquierdo

We present here a detailed analysis of the local symmetries of supergravity in an arbitrary dimension D, both in the component and superfield approaches, using a field-space democracy point of view. As an application, we discuss briefly how a complete description of the local gauge symmetries clarifies the properties of the supergravity-superbrane coupled sy

I. Nakamura, V. Dmitrasinovic

We apply a self-consistent relativistic mean-field variational ``Gaussian functional&#39;&#39; (or Hartree) approximation to the linear $σ$ model with spontaneously and explicitly broken chiral O(4) symmetry. We set up the self-consistency, or ``gap&#39;&#39; and the Bethe-Salpeter equations. We check and confirm the chiral Ward-Takahashi identities, among t

Salah Nasri, Pedro J. Silva, Glenn D. Starkman, Mark Trodden

We consider radion stabilization in hyperbolic brane-world scenarios. We demonstrate that in the context of Einstein gravity, matter fields which stabilize the extra dimensions must violate the null energy condition. This result is shown to hold even allowing for FRW-like expansion on the brane. In particular, we explicitly demonstrate how one putative sourc

Yuri Grats, Anton Rossikhin

Gravitational field of cosmic strings in theories with extra spatial dimensions must differ significantly from that in the Einstein&#39;s theory. This means that all gravity induced properties of cosmic strings need to be revised too. Here we consider the effect of vacuum polarization outside a straight infinitely thin cosmic string embedded in a RS2 brane w

C. P. Burgess, J. Cline, E. Filotas, J. Matias

We identify the effective theory appropriate to the propagation of massless bulk fields in brane-world scenarios, to show that the dominant low-energy effect of asymmetric warping in the bulk is to modify the dispersion relation of the effective 4-dimensional modes. We show how such changes to the graviton dispersion relation may be bounded through the effec

G. Barenboim, L. Borissov, J. Lykken

Recently we proposed a framework for explaining the observed evidence for neutrino oscillations without enlarging the neutrino sector, by introducing CPT violating Dirac masses for the neutrinos. In this paper we continue the exploration of the phenomenology of CPT violation in the neutrino sector. We show that our CPT violating model fits the existing Super

Stefano Pozzorini

This PhD thesis is concerned with one-loop virtual electroweak corrections to arbitrary processes in the high-energy limit. Complete results are presented for the leading and subleading logarithms of large ratios of energy scales to mass scales. These results include the logarithmic dependence on the photon and weak-boson masses, on the light-fermion masses,

A. S. Galoyan, G. L. Melkumov, V. V. Uzhinskii

In the framework of the modified FRITIOF model, the inclusive spectra of the cumulative $π^0$-, $π^- $-mesons and protons produced in the nucleus-nucleus interactions at 4.5 GeV/c/nucleon and 4.2 GeV/c/nucleon are calculated. It is shown that the model reproduces qualitatively, and in some cases quantitatively the main experimental regularities of $π$-mesons

Dmitriy A. Anipko, Ilya F. Ginzburg, Alexey V. Pak

We study possibilities to measure the triple anomalous W-boson couplings to photon in the $eγ\to Wν$ process via its lepton decay channel (with the simplest signature). We found that in the study of the $W$ quadruple momentum $λ$ one can limit himself within a small region in phase space. A way to find this region is proposed. The obtained estimates for $λ$