December 2000 arXiv papers — page 5

Yuri Bazlov

We know the multiplicity of the adjoint representation of a semisimple Lie algebra in its own exterior algebra, but how do its copies distribute themselves between the exterior powers? The answer (the graded multiplicity) is obtained with the aid of Macdonald polynomials.

M. S. Baouendi, Nordine Mir, Linda Preiss Rothschild

In this paper, we study formal mappings between smooth generic submanifolds in multidimensional complex space and establish results on finite determination, convergence and local biholomorphic and algebraic equivalence. Our finite determination result gives sufficient conditions to guarantee that a formal map as above is uniquely determined by its jet at a p

A. I. Molev

The evaluation homomorphisms from the Yangian Y(gl_n) to the universal enveloping algebra U(gl_n) allow one to regard the irreducible finite-dimensional representations of gl_n as Yangian modules. We give necessary and sufficient conditions for irreducibility of tensor products of such evaluation modules.

Z. Bern, D. Dunbar, L. Dixon, B. Julia

We examine the ultraviolet behaviour of supergravity theories as a function of dimension and number of supercharges. We do so by the computation of one and two-loop physical on-shell four point amplitudes. For maximal supergravity, our computations prove the non-renomalisability of supergravity for $D \geq 6$ (including the maximal D=11 case) and give strong

Shin Ishida, Muneyuki Ishida, Tomohito Maeda

Starting from the bi-local Klein-Gordon Equation with spin-independent squared-mass operator, we give a covariant quark representation of general composite meson systems with definite Lorentz transformation properties. For benefit of this representation we are able to deduce automatically the transformation rules of composite mesons for general symmetry oper

Muneyuki Ishida, Shin Ishida, Toshihiko Komada

The results of analyses obtained in Part I are examined from the viewpoint of chiral symmetry. The mass spectra of pi pi system are widely believed to be suppressed generally near the threshold, because of the derivative coupling property of Nambu-Goldstone pi meson. However, this suppression does not hold in the processes with large energy release, and the

Toshihiko Komada, Shin Ishida, Muneyuki Ishida

We analyze the pi pi production amplitudes in the excited Upsilon decay processes, Upsilon(2S)-->Upsilon(1S)pi+pi-, Upsilon(3S)-->Upsilon(1S)pi+pi- and Upsilon(3S)-->Upsilon(2S)pi+pi-, and the pi pi and KKbar production amplitudes in the charmonium decay processes, psi(2S)-->J psi pi+pi- and J psi-->phi pi+pi-, phi K+K-. The amplitudes are parametrized by th

Muneyuki Ishida

The phenomenologically observed property of sigma(600) in our recent analyses of various pi pi-scattering and -production processes is reviewed and compared with the prediction of SU(2) linear sigma model. Furthermore, a possibility of the scalar sigma-nonet (sigma (600), kappa (900), f_0(980) and a_0(980)) forming with the pseudoscalar pi-nonet a linear rep

Kunio Takamatsu

The evidences for sigma(600) and kappa(900) observed in our analyses on the pi pi and K pi scattering phase shift data are described, briefly. The analysis have been performed by the interfering amplitude method, which satisfies the unitarity requirement, using physically meaningful parameters. The introduction of the negative phase shifts (repulsive force)

Shin Ishida, Muneyuki Ishida

It is stated that the requirement of unitarity and of analyticity should be made on the S-matrix elements with right bases, and the ``universality argument" made with the bases, which do not regard quark physical picture, is not right. Accordingly the result of the conventional analyses of the pi pi production amplitudes following to this argument, leadi

S. Chiku

We study the optimized perturbation theory (OPT) at finite temperature, which is a self-consistent resummation method. Firstly, we generalize the idea of the OPT to optimize the coupling constant in lambda phi^4 theory, and give a proof of the renormalizability of this generalized OPT. Secondly, the principle of minimal sensitivity and the criterion of the f

Kazunari Shima

A unified description of spacetime and matter is proposed by using a single irreducible representation of SO(10) Super-Poincare algebra(SO(10)SPA). All (observed) elementary particles except the graviton are the (massless) eigenstates of SO10)SPA composed of fundamental Nambu-Goldstone fermions with spin 1/2, superons, associating with the spontaneous breakd

I. I. Bigi

After a reminder about how $ΔS\neq 0$ physics has been instrumental for the development of the Standard Model I sketch theoretical technologies for dealing with nonperturbative QCD in heavy flavour decays and state predictions for CP odd effects as they were made in 1998. I review the exciting developments in heavy flavour physics as presented at this confer

Joerg Gayler

Data on jet production in deep inelastic e^+ p scattering are presented. The results are compared with pQCD calculations. At low Q^2 no consistent description of the data over all the phase space is available yet. At high Q^2 (>150 GeV^2) the data are well described by pQCD in NLO.

M. L. Chiofalo, S. Succi, M. P. Tosi

We simulate three experimental methods which could be realized in the laboratory to probe the band excitation energies and the momentum distribution of a Bose-Einstein condensate inside an optical lattice. The values of the excitation energies obtained in these different methods agree within the accuracy of the simulation. The meaning of the results in terms

Annette Bussmann-Holder, K. Alex Muller, Roman Micnas, Helmut Buttner

Since the recently reported giant isotope effect on T* [1] could be consistently explained within an anharmonic spin-charge-phonon interaction model, we consider here the role played by stripe formation on the superconducting properties within the same model. This is a two-component scenario and we recast its basic elements into a BCS effective Hamiltonian.

I. B. Thompson, J. Kaluzny, W. Pych, G. Burley

We use masses, radii, and luminosities of the detached eclipsing binary OGLEGC17 derived from photometric and spectroscopic observations to calculate the age and distance of the globular cluster omega Cen. Age versus turnoff mass and age versus luminosity relations from Girardi et al. (2000) yield two independent estimates of the age, 9.1<t<16.7 Gyr and 12.9

S. F. Yelin, P. R. Hemmer

A novel class of coherent nonlinear optical phenomena, involving induced transparency in quantum wells, is considered in the context of a particular application to sensitive long-wavelength infrared detection. It is shown that the strongest decoherence mechanisms can be suppressed or mitigated, resulting in substantial enhancement of nonlinear optical effect

Glenn D. Starkman, Dejan Stojkovic, Mark Trodden

We consider a variant of the brane-world model in which the universe is the direct product of a Friedmann, Robertson-Walker (FRW) space and a compact hyperbolic manifold of dimension $d\geq2$. Cosmology in this space is particularly interesting. The dynamical evolution of the space-time leads to the injection of a large entropy into the observable (FRW) univ

G. C. Branco, F. Krüger, J. C. Romão, A. M. Teixeira

We re-examine spontaneous CP violation at the tree level in the context of the next-to-minimal supersymmetric standard model (NMSSM) with two Higgs doublets and a gauge singlet field. We analyse the most general Higgs potential without a discrete Z_3 symmetry, and derive an upper bound on the mass of the lightest neutral Higgs boson consistent with present e

H. P. Büchler, V. B. Geshkenbein, G. Blatter

We study the superfluid properties of (quasi) one-dimensional bosonic atom gases/liquids in traps with finite geometries in the presence of strong quantum fluctuations. Driving the condensate with a moving defect we find the nucleation rate for phase slips using instanton techniques. While phase slips are quenched in a ring resulting in a superfluid response

M. S. Couto, M. L. Martins, S. G. Alves

Granular materials constitute an intermediate state of matter between fluids and solids. Here we investigate the pattern formation when a grain is displaced by another type of grain in a radial Hele-Shaw cell. We show that several morphologies can occur, ranging from rounded to fingered patterns, interconnected by a continuous crossover. Fourier analyses sho

Vadim Ponomarenko, Dmitri Averin

We have found solution to a model of tunneling between a multi-channel Fermi liquid reservoir and an edge of the principal fractional quantum Hall liquid (FQHL) in the strong coupling limit. The solution explains how the absence of the time-reversal symmetry at high energies due to chiral edge propagation makes the universal two-terminal conductance of the F

Sven Soff, Steffen A. Bass, Adrian Dumitru, ;

We calculate the Gaussian radius parameters of the pion-emitting source in high energy heavy ion collisions, assuming a first order phase transition from a thermalized Quark-Gluon-Plasma (QGP) to a gas of hadrons. Such a model leads to a very long-lived dissipative hadronic rescattering phase which dominates the properties of the two-pion correlation functio

F. Bonechi, N. Ciccoli, M. Tarlini

We describe an approach to the noncommutative instantons on the 4-sphere based on quantum group theory. We quantize the Hopf bundle S^7 --> S^4 making use of the concept of quantum coisotropic subgroups. The analysis of the semiclassical Poisson--Lie structure of U(4) shows that the diagonal SU(2) must be conjugated to be properly quantized. The quantum cois

E. L. Blanton, C. L. Sarazin, J. A. Irwin

We have spatially and spectrally resolved the sources of X-ray emission from the X-ray faint S0 galaxy NGC 1553 using an observation from the Chandra X-ray Observatory. The majority (70%) of the emission in the 0.3 - 10.0 keV band is diffuse, and the remaining 30% is resolved into 49 discrete sources. Most of the discrete sources associated with the galaxy a

Selman Akbulut, Burak Ozbagci

The existence of a positive allowable Lefschetz fibration on a compact Stein surface with boundary was established by Loi and Piergallini by using branched covering techniques. Here we give an alternative simple proof of this fact and construct explicitly the vanishing cycles of the Lefschetz fibration, obtaining a direct identification of the set of compact

Zbyszek P. Karkuszewski, Jakub Zakrzewski, Wojciech H. Zurek

Breakdown of quantum-classical correspondence is studied on an experimentally realizable example of one-dimensional periodically driven system. Two relevant time scales are identified in this system: the short Ehrenfest time t_h and the typically much longer localization time scale T_L. It is shown that surprisingly weak modification of the Hamiltonian may e

Velimir Bardek, Larisa Jonke, Stjepan Meljanac

We study a trapped Bose-Einstein condensate under rotation in the limit of weak, translational and rotational invariant two-particle interactions. We use the perturbation-theory approach (the large-N expansion) to calculate the ground-state energy and the excitation spectrum in the asymptotic limit where the total number of particles N goes to infinity while

M. C. Gonzalez-Garcia, C. Peña-Garay, A. Yu. Smirnov

We have performed a detailed study of the zenith angle dependence of the regeneration factor and distributions of events at SNO and SK for different solutions of the solar neutrino problem. In particular, we discuss oscillatory behaviour and the synchronization effect in the distribution for the LMA solution, the parametric peak for the LOW solution, etc.. P

I. Antoniou, E. Karpov, G. Pronko, E. Yarevsky

We analyze the short-time behavior of the survival probability in the frame of the Friedrichs model for different formfactors. We have shown that this probability is not necessary analytic at the time origin. The time when the quantum Zeno effect could be observed is found to be much smaller than usually estimated. We have also studied the anti-Zeno era and

Christian Bohr

It is one of the most important facts in 4-dimensional topology that not every spherical homology class of a 4-manifold can be represented by an embedded sphere. In 1978, M. Freedman and R. Kirby showed that in the simply connected case, many of the obstructions to constructing such a sphere vanish if one modifies the ambient 4-manifold by adding products of

Ilya L. Shapiro, Joan Sola

In quantum field theory the parameters of the vacuum action are subject to renormalization group running. In particular, the ``cosmological constant'' is not a constant in a quantum field theory context, still less should be zero. In this paper we continue with previous work, and derive the particle contributions to the running of the cosmological and gravit

M. Ciuchini, G. D'Agostini, E. Franco, V. Lubicz

Within the Standard Model, a review of the current determination of the sides and angles of the CKM unitarity triangle is presented, using experimental constraints from the measurements of |\epsilon_K|, |V_{ub}/V_{cb}|, \Delta m_d and from the limit on \Delta m_s, available in September 2000. Results from the experimental search for {B}^0_s-\bar{B}^0_s oscil

Moulay-Tahar Benameur

We prove a cyclic Lefschetz formula for foliations. To this end, we define a notion of equivariant cyclic cohomology and show that its expected pairing with K-theory is well defined. This enables to associate to any invariant transverse current on a compact foliated manifold, a Lefschetz formula for leafwise preserving isometries.

Jose A. Font, Harald Dimmelmeier, Anshu Gupta, Nikolaos Stergioulas

Axisymmetric pulsations of rotating neutron stars can be excited in several scenarios, such as core-collapse, crust and core-quakes and binary mergers and could become detectable either in gravitational waves or high-energy radiation. Here, we present a comprehensive study of all low-order axisymmetric modes of uniformly and rapidly rotating relativistic sta

M-T. Benameur, T. Fack

We define the notion of von Neumann spectral triple and consider the associated index problem. We compute the analytic Chern-Connes character of such a von Neumann spectral triple and prove the corresponding local formula for its Hochschild class. This formula involves the Dixmier trace for $II_{\infty}$ von Neumann algebras. In the case of foliations, we id

M. Lange, M. J. Van Bael, L. Van Look, K. Temst

We investigated the pinning of flux lines in a superconducting film by a regular array of magnetic antidots. The sample consists of a Co/Pt multilayer with perpendicular magnetic anisotropy in which a regular pattern of submicron holes is introduced and which is covered by a type-II superconducting Pb film. The resulting ferromagnetic/superconducting heteros

C. Wolf, S. Dye, M. Kleinheinrich, K. Meisenheimer

We report on deep multi-color imaging (R_5-sigma = 26) of the Chandra Deep Field South, obtained with the Wide Field Imager (WFI) at the MPG/ESO 2.2 m telescope on La Silla as part of the COMBO-17 survey. As a result we present a catalog of 63501 objects in a field measuring 31.5&#39; x 30&#39; with astrometry and BVR photometry. A sample of 37 variable obje

Won Suk Bae, Y. M. Cho, Sei-Hoon Moon

We consider a brane world residing in the interior region inside the horizon of the D3-brane. The horizon size then can be interpreted as the compactification size. The macroscopically large size of extra dimensions can be derived from the underlying string theory that has only one physical scale, {\it i.e.,} the string scale. Then, the hierarchy between the

W. Wonneberger

A model of interacting one--dimensional fermions confined to a harmonic trap is proposed. The model is treated analytically to all orders of the coupling constant by a method analogous to that used for the Luttinger model. As a first application, the particle density is evaluated and the behavior of Friedel oscillations under the influence of interactions is

J. A. Aguilar-Saavedra

We present an analysis of the sensitivity of the TESLA e+ e- collider to top flavour-changing neutral couplings to the Z boson and photon. We consider the cases without beam polarization, with only e- polarization and with e- and e+ polarization, showing that the use of the latter substantially enhances the sensitivity to discover or bound these vertices. Fo

Alberto S. Cattaneo, Giovanni Felder, Lorenzo Tomassini

We give an explicit construction of a deformation quantization of the algebra of functions on a Poisson manifolds, based on Kontsevich&#39;s local formula. The deformed algebra of functions is realized as the algebra of horizontal sections of a vector bundle with flat connection.

Dietrich Bodeker

The effective theory for the dynamics of hot non-Abelian gauge fields with spatial momenta of order of the magnetic screening scale g^2 T is described by a Boltzmann equation. The dynamical content of this theory is explored. There are three relevant frequency scales, g T, g^2 T and g^4 T, associated with plasmon oscillations, multipole fluctuations of color

Axel Brandenburg, Wolfgang Dobler

Dynamo action is investigated in simulations of locally isotropic and homogeneous turbulence in a slab between open boundaries. It is found that a `pseudo-vacuum&#39; boundary condition (where the field is vertical) leads to strong helicity fluxes which significantly reduce the amplitude of the resulting large scale field. On the other hand, if there is a co

Philip R. Johnson, B. L. Hu

We present a stochastic theory of charges moving in an electromagnetic field using nonequilibrium quantum field theory. We give a first principles&#39; derivation of the Abraham-Lorentz-Dirac-Langevin equation which depicts the quantum expectation value for a particle&#39;s trajectory and its stochastic fluctuations by combining the worldline path integral q

B. L. Hu, Alpan Raval

The thermal radiance felt by a uniformly accelerated detector/oscillator/atom--the Unruh effect-- is often mistaken to be some emitted radiation detectable by an observer/probe/sensor. Here we show by an explicit calculation of the energy momentum tensor of a quantum scalar field that, at least in 1+1 dimension, while a polarization cloud is found to exist a

B. F. Kostenko, V. D. Kuznetsov, M. B. Miller, A. V. Sermyagin

Experimental realizations of QT have so far been limited to teleportation of light. The present communication gives a new experimental scheme for QT of heavy matter. We show that the standard experimental technique used in nuclear physics may be successfully applied to teleportation of spin states of atomic nuclei. It was shown that there are no theoretical

B. L. Hu, Philip R. Johnson

We discuss some common misconceptions in Unruh effect and Unruh radiation for the cases of linear and circular uniform acceleration of a charged particle or detector moving in a quantum field. We point to the need to go beyond Unruh effect and develop a new theoretical framework for treating the stochastic dynamics of particles interacting with quantum field

Yuqing Sun, Mark Hillery, Janos Bergou

The problem of unambiguously distinguishing among nonorthogonal but linearly independent quantum states can be solved by mapping the set of nonorthogonal quantum states onto a set of orthogonal ones, which can then be distinguished without error. Such nonunitary transformations can be performed conditionally on quantum systems; a unitary transformation is ca

Bassano Vacchini

A master equation with a Lindblad structure is derived, which describes the interaction of a test particle with a macroscopic system and is expressed in terms of the operator valued dynamic structure factor of the system. In the case of a free Fermi or Bose gas the result is evaluated in the Brownian limit, thus obtaining a single generator master equation f

A. Winter, S. Massar

We generalize recent work of Massar and Popescu dealing with the amount of classical data that is produced by a quantum measurement on a quantum state ensemble. In the previous work it was shown how spurious randomness generally contained in the outcomes can be eliminated without decreasing the amount of knowledge, to achieve an amount of data equal to the v

Alexei Trifonov, Gunnar Bjork, Jonas Soderholm

We have made the first experimental demonstration of the simultaneous minimum uncertainty product between two complementary observables for a two-state system (a qubit). A partially entangled two-photon state was used to perform such measurements. Each of the photons carries (partial) information of the initial state thus leaving a room for measurements of t

I. A. Stepanov

Earlier, the author found that for the biggest part of chemical reactions the law of conservation of energy must have the following form: dU=dQ+PdV+SUM In the present paper this result is confirmed by other experiments.

Jie Gao

Physically speaking, the delta function like beam-beam nonlinear forces at interaction points (IPs) act as a sum of delta function nonlinear multipoles. By applying the general theory established in ref. 1, in this paper we investigate analytically the beam-beam interaction limited dynamic apertures and the corresponding beam lifetimes for both the round and

Arindam Mitra

If, due to some catastrophe, our classical communication system is destroyed but quantum entangled state survived, in that entanglement age, it is widely believed, the whole world would be communication less. It is discussed that complete entanglement based communication even with security is possible in that scenario. In this context, the notion of cheating

G. Ramalho, A. Arriaga, M. T. Peña

Relativistic quasi-potential equations describing NN scattering are compared. Within the spectator formalism a cancellation is seen to occur between retardation and negative-energy effects.

A. Gargano, L. Coraggio, A. Covello, N. Itaco

We have studied p-shell nuclei using a two-frequency shell-model approach with an effective interaction derived from the Bonn-A nucleon-nucleon potential by means of a G-matrix folded-diagram method. First, we briefly describe our derivation of the effective interaction in a model space composed of harmonic hoscillator wave functions with two different lengt

M. Papa, T. Maruyama, A. Bonasera

We propose a Constraint Molecular Dynamics model for Fermionic system. In this approach the equations of motion of wave packets for the nuclear many-body problem are solved by imposing that the one-body occupation probability $\bar{f}(r,p,t)$ can assume only values less or equal to 1. This condition reflects the Fermionic nature of the studied systems and it

H. Lenske, F. Hofmann, C. M. Keil

Nuclear many-body theory is used to study nuclear matter and finite nuclei at extreme isospin. In-medium interactions in asymmetric nuclear matter are obtained from (Dirac-) Brueckner theory. Neutron skin formation in Ni and Sn isotopes is investigated by relativistic mean-field calculations in DDRH theory with density dependent meson-nucleon vertices. Appli

F. Bissey, A. W. Thomas, I. R. Afnan

The spectral functions and light-cone momentum distributions of protons and neutrons in 3He and 3H are given in terms of the three-nucleon wave function for realistic nucleon-nucleon interactions. To reduce computational complexity, separable expansions are employed for the nucleon-nucleon potentials. The results for the light-cone momentum distributions sug

Monika E. Pietrzyk, Miltcho B. Danailov

In this paper possibilities of a stabilization of large amplitude fluctuations in an intracavity-doubled solid-state laser are studied. The modification of the cross-saturation coefficient by the effect of spatial hole-burning is taken into account. The stabilization of the laser radiation by an increase of the number of modes, as proposed by James et al. (1

A. R. Bishop, K. Ø. Rasmussen, J. Röder, T. Lookman

Through three examples we illustrate some of the concepts and ingredients required for pattern formation at mesoscopic scales. Two examples build on microscopic models where mesoscopic patterns emerge from homogeneous ground states driven into instability by external forcing. In contrast, the third example builds on a mesoscopic phenomenological Ginzburg-Lan

O. Bohigas, P. Leboeuf, M. -J. Sanchez

New aspects of spectral fluctuations of (quantum) chaotic and diffusive systems are considered, namely autocorrelations of the spacing between consecutive levels or spacing autocovariances. They can be viewed as a discretized two point correlation function. Their behavior results from two different contributions. One corresponds to (universal) random matrix

S. M. Killen, R. S. Johnson

A problem in nonlinear water-wave propagation on the surface of an inviscid, stationary fluid is presented. The primary surface wave, suitably initiated at some radius, is taken to be a slowly evolving nonlinear cylindrical wave (governed by an appropriate Korteweg-de Vries equation); the depth is assumed to be varying in a purely radial direction. We consid

Jayendra N. Bandyopadhyay, A. Lakshminarayan, Vijay B. Sheorey

The classical and the quantal problem of a particle interacting in one-dimension with an external time-dependent quadratic potential and a constant inverse square potential is studied from the Lie-algebraic point of view. The integrability of this system is established by evaluating the exact invariant closely related to the Lewis and Riesenfeld invariant fo

A. A. Ovchinnikov

We present the simple and direct proof of the determinantal formula for the scalar product of Bethe eigenstate with an arbitrary dual state. We briefly review the direct calculation of the general scalar product with the help of the factorizing operator and the construction of the factorizing operator itself. We also comment on the previous determination of

Markus Kunze, Alan D. Rendall

We set up and analyze a model of radiation damping within the framework of continuum mechanics, inspired by a model of post-Newtonian hydrodynamics due to Blanchet, Damour and Schaefer. In order to simplify the problem as much as possible we replace the gravitational field by the electromagnetic field and the fluid by kinetic theory. We prove that the result

A. P. Veselov

A generalisation of the Stieltjes relations for the Painlevé-IV transcendents and their higher analogues determined by the dressing chains is proposed. It is proven that if a rational function from a certain class satisfies these relations it must be a solution of some higher Painlevé-IV equation. The approach is based on the interpretation of the Stieltjes

Randall D. Kamien

We show that Scherk&#39;s first surface, a one-parameter family of solutions to the minimal surface equation, may be written as a linear superposition of other solutions with specific parametric values.

J. A. J. Hall, K. I. M. McKinnon

This paper introduces a class of linear programming examples which cause the simplex method to cycle indefinitely and which are the simplest possible examples showing this behaviour. The structure of examples from this class repeats after two iterations. Cycling is shown to occur for both the most negative reduced cost and steepest edge column selection crit

James D. Lewis

We give an explicit description of a real regulator from the cohomology of a Milnor complex associated to a projective algebraic manifold, to a certain quotient of Deligne cohomology.

D. Ferus, K. Leschke, F. Pedit, U. Pinkall

The paper develops the fundamentals of quaternionic holomorphic curve theory. The holomorphic functions in this theory are conformal maps from a Riemann surface into the 4-sphere, i.e., the quaternionic projective line. Basic results such as the Riemann-Roch Theorem for quaternionic holomorphic vector bundles, the Kodaira embedding and the Pluecker relations

Jacob van den Berg, Balint Toth

We consider a linear sequence of `nodes&#39;, each of which can be in state 0 (`off&#39;) or 1 (`on&#39;). Signals from outside are sent to the rightmost node and travel instantaneously as far as possible to the left along nodes which are `on&#39;. These nodes are immediately switched off, and become on again after a recovery time. The recovery times are ind

Balint Toth, Wendelin Werner

We show that the two-component system of hyperbolic conservation laws $\partial_t ρ+ \partial_x (ρu) =0 = \partial_t u + \partial_x ρ$ appears naturally in the formally computed hydrodynamic limit of some randomly growing interface models, and we study some properties of this system. We show that the two-component system of hyperbolic conservation laws $\par

Mireille Bousquet-Melou, Gilles Schaeffer

In the first part of this paper, we enumerate exactly walks on the square lattice that start from the origin, but otherwise avoid the non positive horizontal half-axis. We call them &#34;walks on the slit plane&#34;. We count them by their length, and by the coordinates of their endpoint. The corresponding three variable generating function is algebraic of d

O. Arratia, M. A. del Olmo

We construct the induced representations of the null-plane quantum Poincaré and quantum kappa Galilei algebras in (1+1) dimensions. The induction procedure makes use of the concept of module and is based on the existence of a pair of Hopf algebras with a nondegenerate pairing and dual bases.

Alberto Barchielli, Anna Maria Paganoni

The theory of measurements continuous in time in quantum mechanics (quantum continual measurements) has been formulated by using the notions of instrument and positive operator valued measure, functional integrals, quantum stochastic differential equations and classical stochastic differential equations (SDE&#39;s). Various types of SDE&#39;s are involved, a

H. Belich, O. M. Del Cima, M. M. Ferreira, J. A. Helayel-Neto

The low-energy electron-electron scattering potential is derived and discussed for the Maxwell-Chern-Simons model coupled to QED_3 with spontaneous symmetry breaking. One shows that the Higgs mechanism might favour electron-electron bound states.

Dmitri Boulatov, Vladimir Kazakov

We study matrix quantum mechanics at a finite temperature equivalent to one dimensional compactified string theory with vortex (winding) excitations. It is explicitly demonstrated that the states transforming under non-trivial U(N) representations describe various configurations vortices and anti-vortices. For example, for the adjoint representation the Feyn

Branislav Jurco, Peter Schupp, Julius Wess

Noncommutative gauge fields (similar to the type that arises in string theory with background B-fields) are constructed for arbitrary nonabelian gauge groups with the help of a map that relates ordinary nonabelian and noncommutative gauge theories (Seiberg-Witten map). As in our previous work we employ Kontsevich&#39;s formality and the concept of equivalent

Paolo Furlan, Ludmil Hadjiivanov, Ivan Todorov

A class of indecomposable representations of U_q(sl_n) is considered for q an even root of unity (q^h = -1) exhibiting a similar structure as (height h) indecomposable lowest weight Kac-Moody modules associated with a chiral conformal field theory. In particular, U_q(sl_n) counterparts of the Bernard-Felder BRS operators are constructed for n=2,3. For n=2 a

Paul A. Pearce, Leung Chim, Changrim Ahn

We consider the massive tricritical Ising model M(4,5) perturbed by the thermal operator phi_{1,3} in a cylindrical geometry and apply integrable boundary conditions, labelled by the Kac labels (r,s), that are natural off-critical perturbations of known conformal boundary conditions. We derive massive thermodynamic Bethe ansatz (TBA) equations for all excita

Mohsen Alishahiha, Harald Ita, Yaron Oz

We propose a form of the effective action of the tachyon and gauge fields for brane-antibrane systems and non-BPS Dp-branes, written in terms of the supercurvature. Kink and vortex solutions with constant infinite gauge field strength reproduce the exact tensions of the lower-dimensional D-branes. We discuss the relation to BSFT and other models in the liter

H. Garcia-Compean, O. Obregon, C. Ramirez, M. Sabido

Strong/weak coupling duality in Chern-Simons supergravity is studied. It is argued that this duality can be regarded as an example of superduality. The use of supergroup techniques for the description of Chern-Simons supergravity greatly facilitates the analysis.

Gennaro Corcella, Elinor K. Irish, Michael H. Seymour

We discuss recent improvement in the treatment of gluon radiation in top production and decay in e+e- processes according to the HERWIG event generator and show studies on the top mass reconstruction at the future Linear Collider.

Gian F. Giudice, Edward W. Kolb, Antonio Riotto, Dmitry V. Semikoz

Standard Model neutrinos are not usually considered plausible dark matter candidates because the usual treatment of their decoupling in the early universe implies that their mass must be sufficiently small to make them ``hot&#39;&#39; dark matter. In this paper we show that decoupling of Standard Model neutrinos in low reheat models may result in neutrino de

Richard F. Lebed

We discuss a little-studied class of weak decay modes sensitive to only one quark topology at leading order in G_F: M --> m gamma, where M,m are mesons with completely distinct flavor quantum numbers. Specifically, they proceed via the annihilation of the valence quarks through a W and the emission of a single hard photon, and thus provide a clear separation

G. Gelmini, P. Gondolo

We show that in the late-infall model of our galactic halo by P. Sikivie the expected phase of the annual modulation of a WIMP halo signal in direct detection experiments is opposite to the one usually expected. If a non-virialized halo component due to the infall of (collisionless) dark matter particles cannot be rejected, an annual modulation in a dark mat

J. L. Goity, W. Roberts

The radiative decays of $D^*$, $B^*$, and other excited heavy mesons are analyzed in a relativistic quark model for the light degrees of freedom and in the limit of heavy quark spin-flavor symmetry. The analysis of strong decays carried out in the corresponding chiral quark model is used to calculate the strong decays and determine the branching ratios of th

J. Bernabeu

In these lectures the following topics are considered: historical remarks and general properties, Dirac and Majorana neutrino masses, effective lagrangian approach, the seesaw mechanism, the number of active left-hauded neutrino species, the light neutrino mass matrix, the direct measurement of neutrino masses, double beta decay, neutrino oscillations in vac

J. Berges, C. Wetterich

A Higgs description for the QCD vacuum in the limit of two quark flavors is proposed. Complete ``spontaneous breaking'' of color symmetry is realized by condensation of an adjoint quark-antiquark and a quark-quark pair. The vacuum is invariant under isospin symmetry applying color and flavor transformations simultaneously. All elementary excitations acquire

B. E. Cox, J. R. Forshaw, L. Lonnblad

The diffractive production of vector bosons at the Tevatron is studied. We take a hard pomeron flux and use the H1 parton density functions extracted from their measurement of F_2^{D(3)}. To this we add a reggeon exchange contribution. We find that the ratio of diffractive to non-diffractive W boson production is in good agreement with the CDF data. We note

Debrupa Chakraverty, Debajyoti Choudhury

We investigate the role that baryon number violating interactions may play in $B$ phenomenology. Present in various grand unified theories, supersymmetric theories with R-parity violation and composite models, a diquark state could be quite light. Using the data on B decays as well as $B - {\bar B}$ mixing, we find strong constraints on the couplings that su

S. V. Goloskokov

We study the spin-dependent cross-sections of vector meson photoproduction for longitudinally and transversely polarized photons within a QCD- model. The dependence of the $σ_T/σ_L$ ratio on the photon virtuality and on the meson wave function is analysed.

J. -M. Frere, M. V. Libanov, S. V. Troitsky

We develop an approach to the origin of three generations of the Standard Model fermions from one generation in a higher-dimensional theory, where four-dimensional fermions appear as zero modes trapped in the core of a topological defect, and the hierarchy of masses and mixings is produced by wave function overlaps in extra dimensions. We present a model wit

K. S. Babu, S. M. Barr, Ilja Dorsner

The dipole moments of the leptons and quarks are matrices in flavor space, which can potentially reveal as much about the flavor structure of the theory as do the mass matrices. The off-diagonal elements of the dipole matrices lead to flavor-changing decays such as μ-> e γ, while the imaginary parts of the diagonal elements give rise to electric dipole momen

Oleg Yakovlev

I review recent progress on the Higgs production in gamma gamma collisions at the photon mode of the Next Linear Collider (NLC). I mainly focus on two particular topics. The first topic is the Higgs-two photon vertex, which is sensitive to new physics, and can be considered a counter of the number of new heavy particles. I recall the results on QCD and elect

Poul-Erik N. Braad, Steen Hannestad

We have investigated the evolution of the neutrino asymmetry in active-sterile neutrino oscillations in the early universe. We find that there are large regions of parameter space where the asymmetry is extremely sensitive to variations in the initial asymmetry as well as the external parameters (the mass difference and the mixing angle). In these regions th

Dongsheng Du, Deshan Yang, Guohuai Zhu

Since b quark mass is not asymptotically large, chirally enhanced corrections which arise from twist-3 wave functions may be important in B decays. We thus evaluate the hadronic matrix elements with the emitted meson described by leading twist and twist-3 distribution amplitudes $Φ_p(x)$. After summing over the four &#34;vertex correction&#34; diagrams, we o