April 1998 arXiv papers — page 7

T. Arakawa, T. Suzuki

We construct a family of exact functors from the BGG category of representations of the Lie algebra sl to the category of finite-dimensional representations of the degenerate (or graded) affine Hecke algebra H of GL. These functors transform Verma modules to standard modules or zero, and simple modules to simple modules or zero. Any simple H-module can be th

T. Arakawa, T. Suzuki, A. Tsuchiya

We introduce a class of induced representations of the degenerate double affine Hecke algebra of gl_N and analyze their structure mainly by means of intertwiners. We also construct them from modules of the affine Lie algebra using Knizhnik-Zamolodchikov connections in the conformal field theory. This construction provides a natural quotient of induced module

A. van Hameren, R. Kleiss

We report on experience with an investigation of the analytic structure of the solution of certain algebraic complex equations. In particular the behavior of their series expansions around the origin is discussed. The investigation imposes the need for an analysis of the singularities and the Riemann sheets of the solution, in which numerical methods are use

Z. S. Wang, Amand Faessler, C. Fuchs, V. S. Uma Maheswari

This work investigates the collective motion of kaons in heavy ion reactions at SIS energies (about 1-2 GeV/nucleon). A radial collective flow of $K^+$ mesons is predicted to exist in central Au + Au collisions, which manifests in a characteristic "shoulder-arm" shape of the transverse mass spectrum of the midrapidity $K^+$ mesons. The $K^+$ radial f

C. Dong, G. Mason

We establish a quantum Galois correspondence for compact Lie groups of automorphisms acting on a simple vertex operator algebra.

Lev Aizenberg

Generalizing the classical result of Bohr, we show that if an n-variable power series converges in an n-circular bounded complete domain D and its sum has modulus less than 1, then the sum of the maximum of the moduli of the terms is less than 1 in the homothetic domain r*D, where r = 1 - (2/3)^(1/n). This constant is near to the best one for the domain D =

D. Drinen

Every AF-algebra arises as a graph algebra in the sense of Kumjian, Pask, Raeburn, and Renault. For AF-algebras, the diagonal subalgebra defined by Stratila and Voiculescu is consistent with Kumjian's notion of diagonal, and the groupoid arising from a well-chosen Bratteli diagram for A coincides with Kumjian's twist groupoid constructed from a diago

Lino Notarantonio

In this paper we study the behavior of the spectrum of a compact, connected Riemannian manifold $(M,g)$ of dimension $d \ge 2$, when we add an increasing number of increasingly small handles. No assumptions on any of the curvatures are needed.

Anatol N. Kirillov

We obtain new combinatorial formulae for modified Hall--Littlewood polynomials, for matrix elements of the transition matrix between the elementary symmetric functions and Hall-Littlewood's ones, and for the number of rational points over the finite field of unipotent partial flag variety. The definitions and examples of generalized mahonian statistic on

Ulf H. Danielsson, Alexios P. Polychronakos

We study a system of external particles of various charges in N =4 super Yang-Mills in the large N limit at finite temperature. We demonstrate that at high enough temperature partial or complete screening of the particles can occur. At zero temperature the total electric or magnetic charge cannot be screened, while higher multipole moments of these charges c

S. S. Xulu

Chamorro and Virbhadra studied, using the energy-momentum complex of Einstein, the energy distribution associated with static spherically symmetric charged dilaton black holes for an arbitrary value of the coupling parameter $γ$ which controls the strength of the dilaton to the Maxwell field. We study the same in Tolman's prescription and get the same re

N. Kawamoto, K. Suehiro, T. Tsukioka, H. Umetsu

We investigate the quantization of even-dimensional topological actions of Chern-Simons form which were proposed previously. We quantize the actions by Lagrangian and Hamiltonian formulations {à} la Batalin, Fradkin and Vilkovisky. The models turn out to be infinitely reducible and thus we need infinite number of ghosts and antighosts. The minimal actions of

Radhika Vathsan

The two-dimensional anyon system, when reduced to one dimension, yields models related to the Calogero-Sutherland model. One such reduction leads to a new model with a class of exact solutions. This model is one of a family of models obtained upon dimensional reduction of spherically symmetric models in arbitrary dimensions.

Scott Thomas, James D. Wells

Massive vector-like electroweak doublets are generic in many extensions of the standard model. Even though one member of the doublet is necessarily electrically charged these particles are not easily detected in collider experiments. The neutral and charged states within the doublet are split by electroweak symmetry breaking. In the absence of mixing with ot

J. F. Gunion

I discuss the exciting prospects for Higgs and technicolor Goldstone boson physics at a muon collider.

Carl E. Carlson, Nimai C. Mukhopadhyay

We show that constraints from perturbative QCD calculations play a role in the nucleon to Delta(1232) electromagnetic transition even at moderate momentum transfer scales. The pQCD constraints, tied to real photoproduction data and unseparated resonance response functions, lead to explicit forms for the helicity amplitudes wherein the E2/M1 ratio remains sma

Francis Halzen, David Saltzberg

A high-energy neutrino telescope, such as the operating AMANDA detector, may detect neutrinos produced in sources, possibly active galactic nuclei or gamma-ray bursts, distant by a thousand megaparsecs. These sources produce mostly nu_e or nu_mu neutrinos. Above 1 PeV, nu_e and nu_mu are absorbed by charged-current interactions in the Earth before reaching t

I. Bojak, M. Stratmann

We present a calculation of the next-to-leading order (O(alpha_s^2 alpha)) QCD corrections to heavy flavor photoproduction with longitudinally polarized beams. We apply our results to study the longitudinal spin asymmetry for the total charm quark production cross section which will be utilized by the forthcoming COMPASS experiment at CERN to obtain first di

G. Kramer, B. Potter

We present next-to-leading order calculations of one- and two-jet production in eP collisions at HERA for photon virtualities in the range 1<Q^2<100 GeV^2. Soft and collinear singularities are extracted using the phase space slicing method. Numerical results are presented for HERA conditions with the Snowmass jet definition. The transition between photoprodu

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

We analyze the heavy quark bound state spectrum using an order-dependent conformal mapping to re-sum the perturbative expansion for current correlators. The procedure consists of two main steps. Firstly, the Borel plane structure of the truncated perturbative expression is modified to ensure consistency with the operator product expansion. This is analogous

G. A. Schuler

Within the NRQCD factorization approach the production of heavy quarkonia can be calculated in perturbative QCD in terms of a few production-process-independent NRQCD matrix elements. We test the universality of these long-distance matrix elements by comparing their values as determined from charmonium production at p pbar, e p, and e+ e- colliders, and in Z

Anjan S. Joshipura

The constraints on trilinear R parity violating couplings $λ&#39;_{ijk}$ following from ({\em i}) the neutrino mass resulting due to the induced vacuum expectation value for the sneutrino and (ii) the charm squark interpretation for the HERA anomalous events are discussed in this talk.}

Q. H. Zhang

Multi-pion correlations effect on three-pion interferometry is studied. It is shown that multi-pion correlations decrease both the apparent radius of the source and the coherent source parameter derived from three-pion interferometry. The data of OPAL group are discussed.

Paolo M. Gensini

Expanded and updated version of a talk originally presented at ``IVth Int. Symp. on Pion--Nucleon Physics and the Structure of the Nucleon&#39;&#39;, Bad Honnef, 9--13 September 1991, originally published in $πN$ Newletter 6 (1992) 21--32. Table of contents: 1. Introduction. 2. $σ$--terms and ``measurements&#39;&#39; of the strange--quark scalar density of t

K. Terasaki

Two pion Decays of K mesons, K_L-K_S mass difference, two photon decay and the Dalitz decays of K_L are studied systematically by assuming that their amplitude can be described in terms of a sum of short distance and long distance contributions. Dominance of the short distance effect on the K_L-K_S mass difference will be checked by the Dalitz decays of K_L

A. Belyaev, E. Boos, L. Dudko

Search for single top quark and Higgs boson production is among the main goals for the upgraded Tevatron. We study the feasibility of single top quark and Higgs boson search at Tevatron both together since these processes have very similar final state signatures and so backgrounds. Calculation of the cross sections and a detailed analysis of various kinemati

G. Clément, A. Fabbri

We derive and discuss black-hole solutions to the gravitating O(3) $σ$ model in (2+1) dimensions. Three different kinds of static black holes are found. One of these resembles the static BTZ black hole, another is completely free of singularities, and the last type has the same Penrose diagram as the (3+1)-dimensional Schwarzschild black hole. We also constr

Nathalie Deruelle, Jean-Philippe Uzan

We briefly recall the problem of defining conserved quantities such as energy in general relativity, and the solution by introducing a symmetric background. We apply the general formalism to perturbed Robertson-Walker spacetimes with de Sitter geometry as background. We relate the obtained conserved quantities to Traschen&#39;s integral constraints and menti

Tetsuo Nozawa, Nikolaos Stergioulas, Eric Gourgoulhon, Yoshiharu Eriguchi

We conduct a direct comparison of three different representative numerical codes for constructing models of rapidly rotating neutron stars in general relativity. Our aim is to evaluate the accuracy of the codes and to investigate how the accuracy is affected by the choice of interpolation, domain of integration and equation of state. In all three codes, the

Karim A. Malik, David Wands

We show how gauge-invariant cosmological perturbations may be constructed by an unambiguous choice of hypersurface-orthogonal time-like vector field (i.e., time-slicing). This may be defined either in terms of the metric quantities such as curvature or shear, or using some matter field. As an example, we show how linear perturbations in the covariant fluid-f

Shiyi Chen, Yuefan Deng, Xiaobo Nie, Yuhai Tu

Three-dimensional molecular dynamics simulations of dissipative particles (~ 10^6) are carried out for studying the clustering kinetics of granular media during cooling. The inter-connected high particle density regions are identified, showing tube-like structures. The energy decay rates as functions of the particle density and the restitution coefficient ar

A. W. Sandvik

We present results of extensive quantum Monte Carlo simulations of the three-dimensional (3D) S=1/2 Heisenberg antiferromagnet. Finite-size scaling of the spin stiffness and the sublattice magnetization gives the critical temperature Tc/J = 0.946 +/- 0.001. The critical behavior is consistent with the classical 3D Heisenberg universality class, as expected.

J. Hausmann, P. Rujan

We consider the behavior of an Ising ferromagnet obeying the Glauber dynamics under the influence of a fast switching, random external field. In Part I, we introduced a general formalism for describing such systems and presented the mean field theory. In this article we derive results for the one dimensional case, which can be only partially solved. Monte Ca

U. Schollwoeck

In applications of White&#39;s Density Matrix Renormalization Group (DMRG) algorithm, computation time is dominated by the diagonalisation of large sparse Hamiltonians by iterative diagonalisation algorithms, whose convergence can be decisively accelerated by the usage of good start vectors. In this paper I show how, using the Marshall sign rule, in a wide c

J. Hausmann, P. Rujan

We consider the behavior of an Ising ferromagnet obeying the Glauber dynamics under the influence of a fast switching, random external field. After introducing a general formalism for describing such systems, we consider here the mean-field theory. A novel type of first order phase transition related to spontaneous symmetry breaking and dynamic freezing is f

Stephen J. Cornell, Michael R. Swift, Alan J. Bray

We consider a randomly forced particle moving in a finite region, which rebounds inelastically with coefficient of restitution r on collision with the boundaries. We show that there is a transition at a critical value of r, r_c\equiv e^{-π/\sqrt{3}}, above which the dynamics is ergodic but beneath which the particle undergoes inelastic collapse, coming to re

Lando Caiani, Lapo Casetti, Marco Pettini

The Hamiltonian dynamics of the classical $ϕ^4$ model on a two-dimensional square lattice is investigated by means of numerical simulations. The macroscopic observables are computed as time averages. The results clearly reveal the presence of the continuous phase transition at a finite energy density and are consistent both qualitatively and quantitatively w

E. Hernandez, C. Goze, P. Bernier, A. Rubio

We present a comparative study of the energetic, structural and elastic properties of carbon and composite single-wall nanotubes, including BN, BC3 and BC2N nanotubes, using a non-orthogonal tight-binding formalism. Our calculations predict that carbon nanotubes have a higher Young modulus than any of the studied composite nanotubes, and of the same order as

R. Bulla, A. C. Hewson, Th. Pruschke

We present a new method to calculate directly the one-particle self-energy of an impurity Anderson model with Wilson&#39;s numerical Renormalization Group method by writing this quantity as the ratio of two correlation functions. This way of calculating Sigma(z) turns out to be considerably more reliable and accurate than via the impurity Green&#39;s functio

Andrzej Z. Gorski

The fractal properties of the energy spectra of quantum systems are discussed in connection with the paper by Sáiz and Martínez [Phys. Rev. E 54, 2431 (1996)]. It is shown that for discrete energy levels the Hausdorff--Basicovitch dimension is zero and differs from the Renyi scaling exponents computed by the standard box counting algorithm. The Renyi exponen

M. Viskum, H. Kjeldsen, T. R. Bedding, T. H. Dall

We present new spectroscopic and photometric time series observations of the delta Scuti star FG~Vir. We detect the oscillations via changes in the equivalent widths of hydrogen and metal absorption lines. From the ratios between spectroscopic and photometric amplitudes, we assign l values to the eight strongest oscillation modes. In particular, we identify

A. V. Sweigart, M. Catelan

Recent Hubble Space Telescope observations have found that the horizontal branches (HB&#39;s) in the metal-rich globular clusters NGC 6388 and NGC 6441 slope upward with decreasing B-V. Such a slope is not predicted by canonical HB models and cannot be produced by either a greater cluster age or enhanced mass loss along the red-giant branch (RGB). The peculi

Rudy Wijnands, Michiel van der Klis

The precise origins of the millisecond radio pulsars, discovered in the early 1980s, remain uncertain until this day. They plausibly evolve from accreting low magnetic-field neutron stars in X-ray binary systems. If so, these stars should spin at millisecond rates. In accordance with this idea, quasi-periodic oscillations discovered in X-ray binaries around

Jay A. Frogel

Surface brightness maps at 12 microns, derived from observations with the Infrared Astronomical Satellite (IRAS), are used to estimate the integrated flux at this wavelength from the Galactic bulge as a function of galactic latitude along the minor axis. A simple model was used to remove Galactic disk emission (e.g. unresolved stars and dust) from the IRAS m

M. Lopez-Corredoira, F. Garzon, P. L. Hammersley, T. J. Mahoney

A new approach to the study of the large-scale stellar cluster distribution in the Galaxy based on two-point correlation techniques is presented. The basic formalism for this method is outlined and its applications are then investigated by the use of a simple model of cluster distribution in the Galaxy. This provides an estimate of the potentials of the two-

M. A. Jones, J. N. Fry

In efforts to demonstrate the linear Hubble law v = Hr from galaxy observations, the underlying simplicity is often obscured by complexities arising from magnitude-limited data. In this paper we point out a simple but previously unremarked fact: that the shapes and orientations of structures in redshift space contain in themselves independent information abo

P. Armstrong, P. M. Chadwick, P. J. Cottle, J. E. Dickinson

The design, construction and operation of the University of Durham ground-based gamma ray telescope is discussed. The telescope has been designed to detect gamma rays in the < 200 GeV region and to achieve good discrimination between gamma ray and hadron initiated showers in the higher energy region (> 300 GeV). The telescope was commissioned in 1995 and a d

S. Talon, C. Charbonnel

We use the measures of Li and rotational velocities in F Hyades stars to assess the role of the wind-driven meridian circulation and of shear turbulence in the transport of angular momentum in stars of different masses. Our models include both element segregation and rotation-induced mixing, and we treat simultaneously the transport of matter and angular mom

Jimmy A. Irwin, Craig L. Sarazin

The X-ray colors and X-ray-to-optical luminosity ratios (L_X/L_B) of 61 early- type galaxies observed with the ROSAT PSPC are determined. The colors indicate that the X-ray spectral properties of galaxies vary as a function of L_X/L_B. The brightest X-ray galaxies have colors consistent with thermal emission from hot gas with roughly the same metallicity of

Marc-Antoine Miville-Deschenes, Gilles Joncas, Edith Falgarone

High resolution 21 cm observations of the Ursa Major cirrus revealed highly filamentary structures down to the 0.03 pc resolution. These filaments, still present in the line centroid map, show multi-Gaussian components and seem to be associated with high vorticity regions. Probability density functions of line centroid increments and structure functions were

R. D. Davies, A. Wilkinson

Galactic synchrotron emission is a potentially confusing foreground, both in total power and in polarization, to the Cosmic Microwave Background Radiation. It also contains much physical information in its own right. This review examines the amplitude, angular power spectrum and frequency spectrum of the synchrotron emission as derived from the presently ava

J. -P. Kneib, D. Alloin, R. Pello

We present new elements in the identification of the lens-system producing the 4 images of the BAL quasar H1413+117, based on the recent HST/NICMOS-2/F160W observations. After a careful PSF subtraction of the 4 images of the quasar, the residual H image reveals the presence of a faint object (H~20.5) within the region enclosed by the 4 quasar images. This ob

S. M. Bennett, C. Moss

As part of a continuing study of the effect of cluster environment on the star formation properties of galaxies, we have undertaken an H-alpha objective prism survey of the nearby cluster, Abell 1060. We detect 33 galaxies in emission, 24 of which are cluster members. We present new radial velocity measurements and H-alpha+[NII] equivalent widths and fluxes

Palle Moller, Stephen J. Warren

We present HST WFPC2 observations in three bands (F450W, F467M and F814W) of a group of three galaxies at z=2.8 discovered in a ground-based narrow-band search for Lyman alpha emission near the z=2.8 quasar PKS0528-250. One of the galaxies is a damped (DLA) absorber and these observations bear on the relation between the DLA clouds and the Lyman-break galaxi

Satoshi Nozawa, Naoki Itoh, Yasuharu Kohyama

We calculate the relativistic thermal bremsstrahlung Gaunt factor for the high-temperature plasma which exists in clusters of galaxies. We calculate the Gaunt factor by employing the Bethe-Heitler cross section corrected by the Elwert factor. The calculations in this paper are made for the fully ionized plasma for the following cases: Z = 10 (Ne), 12 (Mg), 1

R. Tantalo, C. Chiosi, A. Bressan, P. Marigo

In this study we present a simple model of elliptical galaxies aimed at interpreting the gradients in colours and narrow band indices observed across these systems. Salient features of the model are the gradients in mass density and star formation and infall of primordial gas aimed at simulating the collapse of a galaxy into the potential well of dark matter

Y. Yoshinari, P. C. Hammel, S-W. Cheong

^139La nuclear magnetic resonance studies reveal markedly different magnetic properties of the two sites created by the charged domain wall formation in La_(5/3)Sr_(1/3)NiO_4. NMR is slow compared to neutron scattering; we observe a 30 K suppression in magnetic ordering temperature indicating glassy behavior. Applied magnetic field reorients the in-plane ord

Stephen Sharpe, Robert Singleton,

We discuss the phase diagram of Wilson fermions in the $m_0$--$g^2$ plane for two-flavor QCD. We argue that, as originally suggested by Aoki, there is a phase in which flavor and parity are spontaneously broken. Recent numerical results on the spectrum of the overlap Hamiltonian have been interpreted as evidence against Aoki&#39;s conjecture. We show that th

Michael B. Green, Michael Gutperle

Duality arguments are used to determine D-instanton contributions to certain effective interaction terms of type II supergravity theories in various dimensions. This leads to exact expressions for the partition functions of the finite N D-instanton matrix model in d=4 and 6 dimensions that generalize our previous expression for the case d=10. These results a

Igor N. Mishustin, Ove Scavenius

We study the expansion dynamics of a quark-antiquark plasma droplet from an initial state with restored chiral symmetry. The calculations are made within the linear $σ$ model scaled with an additional scalar field representing the gluon condensate. We solve numerically the classical equations of motion for the meson fields coupled to the fluid-dynamical equa

Pervez Hoodbhoy, Xiangdong Ji, Wei Lu

We introduce gauge-invariant quark and gluon angular momentum distributions after making a generalization of the angular momentum density operators. From the quark angular momentum distribution, we define the gauge-invariant and leading-twist quark {\it orbital} angular momentum distribution $L_q(x)$. The latter can be extracted from data on the polarized an

D. Bailin, G. V. Kraniotis, A. Love

The CP-violating phases in the soft supersymmetry-breaking sector in orbifold compactifications with a continuous Wilson line are investigated. In this case the modular symmetry is the Siegel modular group $Sp(4,Z)$ of genus two. In particular, we study the case that the hidden sector non-perturbative superpotential is determined by the Igusa cusp form ${\ca

Yun Wang, Neta Bahcall, Edwin L. Turner

We derive simple empirical color-redshift relations for $z\la 4$ galaxies in the Hubble Deep Field (HDF) using a linear function of three photometric colors ($U-B$, $B-V$, $V-I$). The dispersion between the estimated redshifts and the spectroscopically observed ones is small for relations derived in several separate color regimes; the dispersions range from

R. Fiore, A. Tiesi, L. Masperi, A. Megevand

The broken-symmetry electroweak vacuum is destabilized in the presence of a magnetic field stronger than a critical value. Such magnetic field may be generated in the phase transition and restore the symmetry inside the bubbles. A numerical calculation indicates that the first-order phase transition is delayed but may be completed for a sufficient low value

Benjamin J. Owen, Lee Lindblom, Curt Cutler, Bernard F. Schutz

Gravitational radiation drives an instability in the r-modes of young rapidly rotating neutron stars. This instability is expected to carry away most of the angular momentum of the star by gravitational radiation emission, leaving a star rotating at about 100 Hz. In this paper we model in a simple way the development of the instability and evolution of the n

D. Ebert, R. N. Faustov, V. O. Galkin

The relativistic transformation properties of the heavy quark-antiquark interaction potential are considered in the framework of the relativistic quark model. A special attention is paid to the long-range (confining) contribution to the spin-independent part of qq bar interaction. The retardation effects are consistently taken into account.

Deborah A. Harris, Kevin S. McFarland

We consider possible detector designs for short-baseline neutrino experiments using neutrino beams produced at the First Muon Collider complex. The high fluxes available at the muon collider make possible high statistics deep-inelastic scattering neutrino experiments with a low-mass target. A design of a low-energy neutrino oscillation experiment on the ``ta

D. Karabali, C. Kim, V. P. Nair

We present an analytical continuum calculation, starting from first principles, of the vacuum wavefunction and string tension for pure Yang-Mills theories in $(2+1)$ dimensions, extending our previous analysis using gauge-invariant matrix variables. The vacuum wavefunction is consistent with what is expected at both high and low momentum regimes. The value o

F. A. Bais, N. M. Muller

We study the quantum mechanics of a system of topologically interacting particles in 2+1 dimensions, which is described by coupling the particles to a Chern-Simons gauge field of an inhomogeneous group. Analysis of the phase space shows that for the particular case of ISO(3) Chern-Simons theory the underlying symmetry is that of the quantum double D(SU(2)),

Hideo Suganuma, Hiroko Ichie, Atsunori Tanaka, Kazuhisa Amemiya

We study the confinement physics in QCD in the maximally abelian (MA) gauge using the SU(2) lattice QCD. To clarify the origin of abelian dominance for the long-range physics, we study the charged-gluon propagator in the lattice QCD, and find that the effective mass $m_{ch} \simeq 0.9 {\rm GeV}$ of the charged gluon is induced by the MA gauge fixing. In the

V. D. Gladush, R. A. Konoplya

We construct a general approach to decomposition of the tangent bundle of pseudo-Riemannian manifolds into direct sums of subbundles, and the associated decomposition of geometric objects. An invariant structure {\cal H}^r defined as a set of r projection operators is used to induce decomposition of the geometric objects into those of the corresponding subbu

M. Yu. Kagan, D. I. Khomskii, M. V. Mostovoy

We study the competition between different possible ground states of the double-exchange model with strong ferromagnetic exchange interaction between itinerant electrons and local spins. Both for classical and quantum treatment of the local spins the homogeneous canted state is shown to be unstable against a phase separation. The conditions for the phase sep

M. Girardi, S. Borgani, G. Giuricin, F. Mardirossian

We present a new determination of the mass function of galaxy clusters, based on optical virial mass estimates for a large sample of 152 nearby (z\le0.15) Abell-ACO clusters, as provided by Girardi et al. (1998). This sample includes both data from the literature and the new ENACS data. The resulting mass function is reliably estimated for masses larger than

Yu Zeng-Hui, Herbert. Pietschmann, Ma Wen-Gan, Han Liang

The QCD corrections to the top-quark pair production via both polarized and unpolarized gluon fusion in $pp$ collisions are calculated in the Minimal Supersymmetric Model(MSSM). We find the MSSM QCD corrections can reach 4% and may be observable in future precise experiments. Furthermore, we studied the CP violation in the MSSM, our results show that the CP

S. Cavallaro

Let A be a commutative unital C*-algebra and let S denote its Gelfand spectrum. We give some necessary and sufficient conditions for a nondegenerate representation of A to be unitarily equivalent to a multiplicative representation on a space L^2(S, m), where m is a positive measure on the Baire sets of S. We also compare these conditions with the multiplicit

Valerio Scarani

The main features of quantum computing are described in the framework of spin resonance methods. Stress is put on the fact that quantum computing is in itself nothing but a re-interpretation (fruitful indeed) of well-known concepts. The role of the two basic operations, one-spin rotation and controlled-NOT gates, is analyzed, and some exercises are proposed.

Takeo Matsuoka

In the context of the supersymmetric unification model in which the massless sector contains extra particles beyond those in the minimal supersymmetric standard model, we obtain mixings between quarks (leptons) and the extra particles which are closely intertwined with Yukawa hierarchies. With the assumption that the unification gauge group $G$ includes $SU(

Masuo Suzuki

The quantum derivatives of $e^{-A}, A^{-1}$ and $\log A$, which play a basic role in quantum statistical physics, are derived and their convergence is proven for an unbounded positive operator $A$ in a Hilbert space. Using the quantum analysis based on these quantum derivatives, a basic equation for the entropy operator in nonequilibrium systems is derived,

Daniel F. V. James

Using a displacement operator formalism, I analyse the depopulation of the vibrational ground state of trapped ions. Two heating times, one characterizing short time behaviour, the other long time behaviour are found. The short time behaviour is analyzed both for single and multiple ions, and a formula for the relative heating rates of different modes is der

Subhash Kak

We investigate the information provided about a specified distributed apparatus of n units in the measurement of a quantum state. It is shown that, in contrast to such measurement of a classical state, which is bounded by log (n+1) bits, the information in a quantum measurement is bounded by 3.7 x n^(1/2) bits. This means that the use of quantum apparatus of

M. Daoud, Y. Hassouni, M. Kibler

A set of operators, the so-called k-fermion operators, that interpolate between boson and fermion operators are introduced through the consideration of an algebra arising from two non-commuting quon algebras. The deformation parameters q and 1/q for these quon algebras are roots of unity with q to the power k being equal to 1. The case k = 2 corresponds to f

N. Gisin, H. Bechmann-Pasquinucci

First, we present a Bell type inequality for n qubits, assuming that m out of the n qubits are independent. Quantum mechanics violates this inequality by a ratio that increases exponentially with m. Hence an experiment on n qubits violating of this inequality sets a lower bound on the number m of entangled qubits. Next, we propose a definition of maximally e

P. P. Mitra, B. Pesaran

Modern imaging techniques for probing brain function, including functional Magnetic Resonance Imaging, intrinsic and extrinsic contrast optical imaging, and magnetoencephalography, generate large data sets with complex content. In this paper we develop appropriate techniques of analysis and visualization of such imaging data, in order to separate the signal

Subhash Kak

According to an ancient Indian text (c. 1700 BC?), the heavens are 1000 earth diameters away from the earth. Other texts took the sun to be halfway to the heavens, so this suggests a distance of the sun about 500 earth diameters from the earth. The confirmation for this supposition comes from the later theories (c. 500 AD) from the same region and from Greek

Anthony J. Baltz, Larry McLerran

An exact solution of the two center time-dependent Dirac equation for pair production induced by ultrarelativistic heavy ion collisions is presented. Cross sections to specific final states approach those of perturbation theory. Multiplicity rates are reduced from perturbation theory.

A. Hamoudi, R. G. Nazmitdinov, Y. Alhassid

We study the fluctuation properties of E2 and M1 transition intensities among T=0,1 states of A = 60 nuclei in the framework of the interacting shell model, using a realistic effective interaction for pf-shell nuclei with a Ni56 as a core. It is found that the B(E2) distributions are well described by the Gaussian orthogonal ensemble of random matrices (Port

D. R. Phillips

This paper examines the role that regularization plays in the definition of the potential used in effective field theory (EFT) treatments of the nucleon-nucleon interaction. I consider $NN$ scattering in $S$-wave channels at momenta well below the pion mass. In these channels (quasi-)bound states are present at energies well below the scale $m_π^2/M$ expecte

H. J. Pirner, B. Friman

We derive Hamiltonian flow equations giving the evolution of the Lipkin Hamiltonian to a diagonal form using continuous unitary transformations. To close the system of flow equations, we present two different schemes. First we linearize an operator with three pairs of creation and destruction operators by reducing it to the $z$ component of the quasi spin. W

Wojciech Broniowski, Wojciech Florkowski

We show that even moderate excess of neutrons over protons in nuclear matter, such as in ${}^{208} Pb$, can lead to large $ρ$-$ω$ mixing at densities of the order of twice the nuclear saturation density and higher. The typical mixing angle is of the order of $10^o$. The mixing may result in noticeable shifts of the positions and widths of resonances. We also

C. Giusti, F. D. Pacati

Cross sections and photon asymmetries of the exclusive 16O(γ,pn)14N and 16O(γ,pp)14C knockout reactions are calculated for transitions to the low-lying discrete final states of the residual nucleus in the photon-energy range between 100 and 400 MeV. Exclusive reactions may represent a test of reaction mechanisms and a promising tool for investigating the dyn

V. D. Efros

Recent papers by Kievsky, Viviani, and Rosati are commented. It is pointed out that the techniques for treatment few-body reactions and bound states in the framework of the hyperspherical approach presented in those papers as original ones were in fact known and have been applied previously.

Z. Papp

The set of Faddeev and Lippmann--Schwinger integral equations for three-body systems involving Coulomb interactions deduced from a ``three-potential&#39;&#39; picture are shown to be compact for all energies and a method of solution is given.

Corran Webster

The relationship between the operator approximation property and the strong operator approximation property has deep significance in the theory of operator algebras. The original definitions of Effros and Ruan, unlike the classical analogues, make no mention of compact operators or compact sets. In this paper we introduce ``compact matrix sets&#39;&#39; whic

Alexander N Panov

The author introduces the notion of a quantum form of an algebraic torus. In the case of diagonal algebraic torus we get the algebra of Laurent twisted polynomials. Quantum algebraic torus can be characterized in terms of exact sequences. The author study the center of QAT. In the case of roots of 1 the new examples of central simple algebras are constructed

Karl Michael Schmidt, Osanobu Yamada

We study the spectrum of spherically symmetric Dirac operators in three-dimensional space with potentials tending to infinity at infinity under weak regularity assumptions. We prove that purely absolutely continuous spectrum covers the whole real line if the potential dominates the mass, or scalar potential, term. In the situation where the potential and the

Lino Notarantonio

Given a separable, locally compact Hausdorff space $X$ and a positive Radon measure $m(dx)$ on it, we study the problem of finding the potential $V(x) \ge 0$ that maximizes the first eigenvalue of the Schrödinger-type operator $L+V(x)$; $L$ is the generator of a local Dirichlet form $(a, D[a])$ on $L^2(X, m(dx))$.

Avijit K. Ganguly

We show that contrary to the claim made by Hallin and Liljenberg in Phys. Rev. D52 1150,(1995), (hep-th/9412188) the thermal correction to the thermal decay or pair production rate for a system placed in a heat bath in the presence of an external electric field, is always nonzero in the finite as well as infinite time limit. Using the formalism outlined ther

Helmuth Huffel, Gerald Kelnhofer

We perform the stochastic quantization of Yang-Mills theory in configuration space and derive the Faddeev-Popov path integral density. Based on a generalization of the stochastic gauge fixing scheme and its geometrical interpretation this result is obtained as the exact equilibrium solution of the associated Fokker--Planck equation. Included in our discussio

Mikhail Z. Iofa, Leopoldo A. Pando Zayas

We computed the statistical entropy of nonextremal 4D and extremal 5D Calabi-Yau black holes and found exact agreement with the Bekenstein-Hawking entropy. The computation is based on the fact that the near-horizon geometry of equivalent representations contains as a factor the Bañados-Teitelboim-Zanelli black hole and on subsequent use of Strominger&#39;s p

Pushan Majumdar, H. S. Sharatchandra

General solution of the non-abelian Gauss law in terms of covariant curls and gradients is presented. Also two non-abelian analogs of the Hodge decomposition in three dimensions are addressed. i) Decomposition of an isotriplet vector field $V_{i}^{a}(x)$ as sum of covariant curl and gradient with respect to an arbitrary background Yang-Mills potential is obt