June 2002 arXiv papers — page 12

Marcela Carena, Debajyoti Choudhury, Rodolfo A. Diaz, Heather E. Logan

We study the production and decays of top squarks (stops) at the Tevatron collider in models of low-energy supersymmetry breaking. We consider the case where the lightest Standard Model (SM) superpartner is a light neutralino that predominantly decays into a photon and a light gravitino. Considering the lighter stop to be the next-to-lightest Standard Model

T. Theuns, M. Bernardi, J. Frieman, P. Hewett

The expansion of the Universe leads to a rapid drop in the mean hydrogen Ly-alpha opacity tau of the intergalactic medium (IGM), tau (1+z)^{3.8}, between redshifts 4 and 3. Measurements of the temperature evolution of the IGM and of the He II opacity both suggest that He II reionizes in this redshift range. We use hydrodynamical simulations to show that the

Erasmo Recami, Ruy H. A. Farias

Within the density matrix formalism, it is shown that a simple way to get decoherence is through the introduction of a "quantum" of time (chronon): which implies replacing the differential Liouville--von Neumann equation with a finite-difference version of it. In this way, one is given the possibility of using a rather simple quantum equation to describe the

Prashant Damle, Titash Rakshit, Magnus Paulsson, Supriyo Datta

This paper addresses the question of whether a ``rigid molecule'' (one which does not deform in an external field) used as the conducting channel in a standard three-terminal MOSFET configuration can offer any performance advantage relative to a standard silicon MOSFET. A self-consistent solution of coupled quantum transport and Poisson's equatio

Chong-Sun Chu, Valentin V. Khoze, Gabriele Travaglini

BMN operators are characterized by the fact that they have infinite R-charge and finite anomalous dimension in the BMN double scaling limit. Using this fact, we show that the BMN operators close under operator product expansion and form a sector in the N=4 supersymmetric Yang-Mills theory. We then identify short-distance limits of general BMN n-point correla

A. J. Blustin, G. Branduardi-Raymont, E. Behar, J. S. Kaastra

We present the analysis of multi-wavelength XMM-Newton data from the Seyfert galaxy NGC 3783, including UV imaging, X-ray and UV lightcurves, the 0.2-10 keV X-ray continuum, the iron K-alpha emission line, and high-resolution spectroscopy and modelling of the soft X-ray warm absorber. The 0.2-10 keV spectral continuum can be well reproduced by a power-law at

Jaume Gomis, Lubos Motl, Andrew Strominger

We investigate the pp-wave limit of the AdS_3\times S^3\times K3 compactification of Type IIB string theory from the point of view of the dual Sym_N(K3) CFT. It is proposed that a fundamental string in this pp-wave geometry is dual to the c=6 effective string of the Sym_N(K3) CFT, with the string bits of the latter being composed of twist operators. The mass

Fayyazuddin

The final state interactions (FSI) in Delta S=-1, Delta C=\pm 1, decays of B-meson are discussed. The rescattering corrections are found to be of order of 15-20%. The strong interaction phase shifts are estimated and their effects on CP-asymmetry are discussed.

Rolando Cardenas, Tame Gonzalez, Yoelsy Leiva, Osmel Martin

In this work we present a model of the universe in which dark energy is modelled explicitely with both a dynamical quintessence field and a cosmological constant. Our results confirm the possibility of a future collapsing universe (for a given region of the parameter space), which is necessary for a consistent formulation of string theory and quantum field t

Kimmo Kainulainen, Keith A. Olive

We review some astrophysical and cosmological properties and implications of neutrino masses and mixing angles. These include: constraints based on the relic density of neutrinos, limits on their masses and lifetimes, BBN limits on mass parameters, neutrinos and supernovae, and neutrinos and high energy cosmic rays.

B. A. Zalesky

The network flow optimization approach is offered for Bayesian segmentation of gray-scale and color images. It is supposed image pixels are characterized by a feature function taking finite number of arbitrary rational values (it can be either intensity values or other characteristics of images). The clusters of homogeneous pixels are described by labels wit

Steven Furlanetto, Abraham Loeb

We study the absorption along lines of sight toward high-z radio sources caused by the 21 cm transition of neutral hydrogen in the intergalactic medium (IGM) before reionization. Using semi-analytic methods, we compute the number density of observable features caused by both ``minihalos'' (bound objects that are unable to cool efficiently because of

F. del Aguila, Ll. Ametller, P. Talavera

We discuss forward-backward charge asymmetries for lepton pair production in association with a large transverse momentum jet at hadron colliders. The measurement of the lepton charge asymmetry relative to the jet direction A_{FB}^j gives a new determination of the effective weak mixing angle sin^2{θ_{eff}^{lept}(M_Z^2)} with in principle a statistical preci

F. Gliozzi, A. Rago

We propose to use the different kinds of vacua of the gauge theories coupled to matter as a laboratory to test confinement ideas of pure Yang-Mills theories. In particular, the very poor overlap of the Wilson loop with the broken string states supports the 't Hooft and Mandelstam confinement criteria. However in the Z(2) gauge-Higgs model we use as a gui

M. Mueller, F. Krzakala, M. Mezard

We study the force-induced unfolding of random disordered RNA or single-stranded DNA polymers. The system undergoes a second order phase transition from a collapsed globular phase at low forces to an extensive necklace phase with a macroscopic end-to-end distance at high forces. At low temperatures, the sequence inhomogeneities modify the critical behaviour.

Akimasa Miyake

We find that multidimensional determinants "hyperdeterminants", related to entanglement measures (the so-called concurrence or 3-tangle for the 2 or 3 qubits, respectively), are derived from a duality between entangled states and separable states. By means of the hyperdeterminant and its singularities, the single copy of multipartite pure entangled s

Regis Lachaume, Fabien Malbet, Jean-Louis Monin

We present a two-layer accretion disc model developed to simultaneously fit optical long baseline visibilities and spectral energy distributions of T Tauri accretion discs. Our model includes viscous heating and absorption of stellar radiation. It analytically expresses the vertical structure of the disc using a two-layer approach: the outer layer is heated

Charles Hellaby, Andrzej Krasinski

The spherically symmetric dust model of Lemaitre-Tolman can describe wormholes, but the causal communication between the two asymptotic regions through the neck is even less than in the vacuum (Schwarzschild-Kruskal-Szekeres) case. We investigate the anisotropic generalisation of the wormhole topology in the Szekeres model. The function E(r, p, q) describes

Curt Cutler

We show that NS's with large toroidal B-fields tend naturally to evolve into potent gravitational-wave (gw) emitters. The toroidal field B_t tends to distort the NS into a prolate shape, and this magnetic distortion can easily dominate over the oblateness ``frozen into'' the NS crust. An elastic NS with frozen-in B-field of this magnitude is clea

A. Hiorth, J. O. Eeg

We present a new chiral quark model for mesons involving a heavy and a light (anti-) quark. The model relates various combinations of a quark - meson coupling constant and loop integrals to physical quantities. Then, some quantities may be predicted and some used as input. The extension from other similar models is that the present model includes the lowest

Davide Lazzati

We analyze the power spectra of the lightcurves of long gamma-ray bursts, dividing the sample in bins of luminosity, using the recently discovered variability-luminosity correlation. We find that the value of the variability parameter strongly correlates with the frequency that contains most of the power in the burst comoving frame. We compute the average po

M. Rybczynski, G. Wilk, Z. Wlodarczyk

We provide description of rapidity spectra of particles produced in p-anti-p collisions using anomalous diffusion approach to account for their non-equilibrium character. In particular, we exhibit connection between multiproduction processes and anomalous diffusion described through the nonlinear Focker-Planck equation with nonlinearity given by the nonexten

P. Salucci, F. Walter, A. Borriello

In this paper we present strong evidence for a core in the density distribution of the dark halo around a (dwarf) galaxy. DDO 47 has a rotation curve that increases linearly from the first data point, at 300 pc, up to to the last one, at 5 kpc. This profile cannot be reproduced unless we consider a dark halo with a flat density core. The optical region of th

M. Bauer, D. Bernard

SLE_k stochastic processes describe growth of random curves which, in some cases, may be identified with boundaries of two dimensional critical percolating clusters. By generalizing SLE_k growths to formal Markov processes on the central extension of the 2d conformal group, we establish a connection between conformal field theories with central charges c_k=(

Gao Xianlong, F. Gleisberg, F. Lochmann, W. Wonneberger

An asymptotically exact many body theory for spin polarized interacting fermions in a one-dimensional harmonic atom trap is developed using the bosonization method and including backward scattering. In contrast to the Luttinger model, backscattering in the trap generates one-particle potentials which must be diagonalized simultaneously with the two-body inte

Semjon Stepanow, Gunter M. Schuetz

In studying the end-to-end distribution function $G(r,N)$ of a worm like chain by using the propagator method we have established that the combinatorial problem of counting the paths contributing to $G(r,N)$ can be mapped onto the problem of random walks with constraints, which is closely related to the representation theory of the Temperley-Lieb algebra. By

M. Fujita, S. Hirenzaki, K. Kume

We investigate the formation cross sections of the deeply bound pionic atoms on halo nuclei theoretically. We consider one-neutron pick-up (d,3He) reaction for the pionic atom formation and find that the formation rate is significantly increased by the existence of the halo neutron with long tail of the wave function. This enhancement is expected to increase

M. A. Sanchis-Lozano

New Physics can show up in various well-known processes already studied in the Standard Model, in particular by modifying decay rates to some extent. In this work, I examine leptonic decays of $Υ$ vector resonances of bottomonium below $B\bar{B}$ production, subsequent to a magnetic dipole radiative structural transition of the vector resonance yielding a ps

Naofumi Kitsunezaki, Shozo Uehara

We investigate how the matrix representation of SU(N) algebra approaches that of the Poisson algebra in the large N limit. In the adjoint representation, the (N^2-1) times (N^2-1) matrices of the SU(N) generators go to those of the Poisson algebra in the large N limit. However, it is not the case for the N times N matrices in the fundamental representation.

Roberto Emparan, Alessandro Fabbri, Nemanja Kaloper

We propose a new approach for using the AdS/CFT correspondence to study quantum black hole physics. The black holes on a brane in an AdS$_{D+1}$ braneworld that solve the classical bulk equations are interpreted as duals of {\it quantum-corrected} $D$-dimensional black holes, rather than classical ones, of a conformal field theory coupled to gravity. We chec

C. Dembowski, B. Dietz, H. -D. Graef, A. Heine

We have measured resonance spectra in a superconducting microwave cavity with the shape of a three-dimensional generalized Bunimovich stadium billiard and analyzed their spectral fluctuation properties. The experimental length spectrum exhibits contributions from periodic orbits of non-generic modes and from unstable periodic orbit of the underlying classica

Bernd A. Berg

The purpose of this article is to provide a starter kit for multicanonical simulations in statistical physics. Fortran code for the $q$-state Potts model in $d=2, 3,...$ dimensions can be downloaded from the Web and this paper describes simulation results, which are in all details reproducible by running prepared programs. To allow for comparison with exact

Yoichi Ando

Unusual features in the in-plane charge transport in lightly hole-doped La_{2-x}Sr_{x}CuO_{4} single crystals are described. Notably, both the in-plane resistivity and the Hall coefficient show a metallic behavior at moderate temperatures even in the long-range-ordered antiferromagnetic phase, which obviously violates the Mott-Ioffe-Regel criterion for the m

George J. Bendo, Robert D. Joseph, Martyn Wells, Pascal Gallais

We investigate star formation along the Hubble sequence using the ISO Atlas of Spiral Galaxies. Using mid-infrared and far-infrared flux densities normalized by K-band flux densities as indicators of recent star formation, we find several trends. First, star formation activity is stronger in late-type (Sc - Scd) spirals than in early-type (Sa - Sab) spirals.

Alakabha Datta, Harry J. Lipkin, Patrick J. O'Donnell

Radial mixing in the pseudoscalar $η-η^{\prime}$ systems can be generated from hyperfine interactions and annihilation terms. For the $η-η^{\prime}$ system we find the effects of radial mixing are appreciable and seriously affect the decay branching ratios for $B \to η(η^{\prime})K(K^*)$, mainly by modifying the $B \to η(η^{\prime})$ form factors. In particu

Takeshi Chiba

We derive a condition for converging a common evolutionary track for k-essence (a scalar field dark energy with non-canonical kinetic terms). For the Lagrangian density V(phi)W(X) with X=dot{phi}^2/2, we find tracker solutions with w_{phi} < w_B exist if Gamma equivalent V&#39;&#39;V/(V&#39;)^2 > 3/2. Here w_{phi}(w_B) is the equation-of-state of the scalar

Kyungwha Park, M. A. Novotny, P. A. Rikvold

We examine a square-lattice nearest-neighbor Ising quantum ferromagnet coupled to $d$-dimensional phonon baths. Using the density-matrix equation, we calculate the transition rates between configurations, which determines the specific dynamic. Applying the calculated stochastic dynamic in Monte Carlo simulations, we measure the lifetimes of the metastable st

N. David Mermin

I explain in elementary terms why the critique of Hess and Philipp in Section 3.2 of quant-ph/0103028 fails to invalidate the nontechnical version of Bell&#39;s theorem I gave twenty years ago, involving two detectors with 3-pole switches and red and green lights.

Berthold-Georg Englert, Giovanna Morigi

1 First Lecture: Basics 1.1 Physical Derivation of the Master Equation 1.2 Some Simple Implications 1.3 Steady State 1.4 Action to the Left 2 Second Lecture: Eigenvalues and Eigenvectors of L 2.1 A Simple Case First 2.2 The General Case 3 Third Lecture: Completeness of the Damping Bases 3.1 Phase Space Functions 3.2 Completeness of the Eigenvectors of L 3.3

Mattias T. Johnsson, Michael Fleischhauer

We present a full quantum analysis of resonant forward four-wave mixing based on electromagnetically induced transparency (EIT). In particular, we study the regime of efficient nonlinear conversion with low-intensity fields that has been predicted from a semiclassical analysis. We derive an effective nonlinear interaction Hamiltonian in the adiabatic limit.

Edward R. Floyd

Discussion of the differences between the trajectory representation of Floyd and that of Bouda and Djama [Phys. Lett. A 285 (2001) 27, quant-ph/0103071] renders insight: while Floyd's trajectories are related to group velocities, Bouda and Djama's are not. Bouda and Djama's reasons for these differences are also addressed.

D. Borisov, P. Exner, R. Gadyl&#39;shin

We consider the Laplacian in a strip $\mathbb{R}\times (0,d)$ with the boundary condition which is Dirichlet except at the segment of a length $2a$ of one of the boundaries where it is switched to Neumann. This operator is known to have a non-empty and simple discrete spectrum for any $a>0$. There is a sequence $0<a_1<a_2<...$ of critical values at which new

S. Albeverio, S. M. Fei, P. Kurasov

General point interactions for the second derivative operator in one dimension are studied. In particular, ${\mathcal P \mathcal T}$-self-adjoint point interactions with the support at the origin and at points $\pm l$ are considered. The spectrum of such non-Hermitian operators is investigated and conditions when the spectrum is pure real are presented. The

Carlton M. Caves, Christopher A. Fuchs, Ruediger Schack

Suppose N parties describe the state of a quantum system by N possibly different density operators. These N state assignments represent the beliefs of the parties about the system. We examine conditions for determining whether the N state assignments are compatible. We distinguish two kinds of procedures for assessing compatibility, the first based on the co

Y. Nosochkov, P. Raimondi, T. O. Raubenheimer, A. Seryi

Compensation of optics errors at the Interaction Point (IP) is essential for maintaining maximum luminosity at the NLC. Several correction systems (knobs) using the Final Focus sextupoles have been designed to provide orthogonal compensation of linear and the second order optics aberrations at IP. Tuning effects of these knobs on the 250 GeV beam were verifi

T. J. Adye, A. Dorigo, R. Dubitzky, A. Forti

A system based on ROOT for handling the micro-DST of the BaBar experiment is described. The purpose of the Kanga system is to have micro-DST data available in a format well suited for data distribution within a world-wide collaboration with many small sites. The design requirements, implementation and experience in practice after three years of data taking b

Leonard M. Sander, Thomas S. Deisboeck

Highly malignant brain tumors such as Glioblastoma Multiforme (GBM) form complex growth patterns in vitro in which invasive cells organize in tenuous branches. Here, we formulate a chemotaxis model for this sort of growth. A key element controlling the pattern is homotype attraction, i.e., the tendency for invasive cells to follow pathways previously explore

F. Spineanu, M. Vlad

We draw attention on the fast oscillatory deviations from the residual non-ambipolarity in the case where electrons are driven by strong magnetic perturbations.

Reuven Ianconescu, L. P. Horwitz

The analysis of the EM radiation from a single charge shows that the radiated power depends on the retarded acceleration of the charge. Therefore, for consistency, an accelerated charge, free from the influence of external forces, should gradually lose its acceleration, until its total energy is radiated. Calculations show that the self force of a charge, wh

Alexander A. Vlasov

As it is known a model of a charged particle with finite size is a good tool to consider the effects of self- action and backreaction, caused by electromagnetic radiation. In this work the &#34;size&#34; of a charged particle is induced by its stochastic Brownian vibration. Appropriate equation of particle&#39;s motion with radiation force is derived. It is

Y. M. Zhao, S. Pittel, R. Bijker, A. Frank

Low-lying collective states involving many nucleons interacting by a random ensemble of two-body interactions (TBRE) are investigated in a collective SD-pair subspace, with the collective pairs defined dynamically from the two-nucleon system. It is found that in this truncated pair subspace collective vibrations arise naturally for a general TBRE hamiltonian

Y. M. Zhao, A. Arima, N. Yoshinaga

In this paper, we discuss the regularities of energy of each angular momentum $I$ averaged over all the states for a fixed angular momentum (denoted as $\bar{E}_I$&#39;s) in many-body systems interacting via a two-body random ensemble. It is found that $\bar{E}_I$&#39;s with $I \sim I_{min}$ (minimum of $I$) or $I_{max}$ have large probabilities (denoted as

Y. M. Zhao, A. Arima, N. Yoshinaga

In this paper, we discuss the angular momentum distribution in the ground states of many-body systems interacting via a two-body random ensemble. Beginning with a few simple examples, a simple approach to predict P(I)&#39;s, angular momenta I ground state (g.s.) probabilities, of a few solvable cases, such as fermions in a small single-j shell and d boson sy

Tim Gorringe, Harold W. Fearing

The induced pseudoscalar coupling $g_p$ is the least well known of the weak coupling constants of the proton&#39;s charged--current interaction. Its size is dictated by chiral symmetry arguments, and its measurement represents an important test of quantum chromodynamics at low energies. During the past decade a large body of new data relevant to the coupling

A. Fix, H. Arenhoevel

A study of the $η$-3N interaction in the energy region near the $η$-^3H elastic scattering threshold is presented. The calculational scheme is based on the four-body scattering formalism. A manageable form of the integral equations is achieved by using a separable ansatz for the driving two-body $ηN$- and NN-forces as well as for the subamplitudes appearing

A. Ramos, M. J. Vicente-Vacas, E. Oset

An error in the computer program which evaluated nucleon spectra following the decay of $Λ$ hypernuclei has been detected. The error affected the final state interaction (FSI) of the nucleons, reducing by a factor ten the nucleon-nucleon (NN) collision probability. When correcting the error, some results and conclusions of Ref. [1] have changed substantially

Qiaoning Chen, Shiyi Chen, Gregory L. Eyink

Three-dimensional (3D) turbulence has both energy and helicity as inviscid constants of motion. In contrast to two-dimensional (2D) turbulence, where a second inviscid invariant--the enstrophy--blocks the energy cascade to small scales, in 3D there is a joint cascade of both energy and helicity simultaneously to small scales. The basic cancellation mechanism

V. B. Taranenko, C. O. Weiss

We demonstrate experimentally and numerically the existence spatial solitons in multiple-quantum-well semiconductor microresonators driven by an external coherent optical field. We discuss stability of the semiconductor-resonator solitons over a wide spectral range around the band edge. We demonstrate the manipulation of such solitons: switching solitons on

L. Accardi, A. N. Pechen, I. V. Volovich

A rigorous derivation of quantum Langevin equation from microscopic dynamics in the low density limit is given. We consider a quantum model of a microscopic system (test particle) coupled with a reservoir (gas of light Bose particles) via interaction of scattering type. We formulate a mathematical procedure (the so-called stochastic golden rule) which allows

Daniel S. Freed

We survey three different ways in which K-theory in all its forms enters quantum field theory. In Part 1 we give a general argument which relates topological field theory in codimension two with twisted K-theory, and we illustrate with some finite models. Part 2 is a review of pfaffians of Dirac operators, anomalies, and the relationship to differential K-th

Emil Horozov

In this paper we give another characterization of the strictly nilpotent elements in the Weyl algebra, which (apart from the polynomials) turn out to be all bispectral operators with polynomial coefficients. This also allows to reformulate in terms of bispectral operators the famous conjecture, that all the endomorphisms of the Weyl algebra are automorphisms

Emil Horozov

The aim of this paper is to solve the bispectral problem for bispectral operators whose order is a prime number. More precisely we give a complete list of such bispectral operators. We use systematically the operator approach and in particular - Dixmier ideas on the first Weyl algebra. When the order is 2 the main theorem is exactly the result of Duistermaat

Christian Hainzl, Robert Seiringer

We present a generalization of the Fefferman-de la Llave decomposition of the Coulomb potential to quite arbitrary radial functions $V$ on $R^n$ going to zero at infinity. This generalized decomposition can be used to extend previous results on $N$-body quantum systems with Coulomb interaction to a more general class of interactions. As an example of such an

Daniel Liberzon, Roberto Tempo

This paper is concerned with the problem of finding a quadratic common Lyapunov function for a family of stable linear systems. We present gradient iteration algorithms which give deterministic convergence for finite system families and probabilistic convergence for infinite families.

Tobias Ekholm, Maxime Wolff

A holonomic knot is a knot in 3-space which arises as the 2-jet extension of a smooth function on the circle. A holonomic knot associated to a generic function is naturally framed by the blackboard framing of the knot diagram associated to the 1-jet extension of the function. There are two classical invariants of framed knot diagrams: the Whitney index (rota

Jairo Bochi, Marcelo Viana

We show that the integrated Lyapunov exponents of $C^1$ volume preserving diffeomorphisms are simultaneously continuous at a given diffeomorphism only if the corresponding Oseledets splitting is trivial (all Lyapunov exponents equal to zero) or else dominated (uniform hyperbolicity in the projective bundle) almost everywhere. We deduce a sharp dichotomy for

Jakob Stix

An investigation of morphisms that coincide topologically is used to generalize to all characteristics and partly reprove Tamagawa&#39;s theorem on the Grothendieck conjecture in anabelian geometry for affine hyperbolic curves. The theorem now deals with π^{tame} of curves over a finitely generated field and its effect on the set of isomorphisms. Universal h

S. Tarasov, A. Shananin

We present a simple geometric construction for smoothing polyhedral utility functions. Keywords: Afriat- Varian theorem, the utility function, the economic indices theory, convex analysis.

Eugene Tokarev

A Banach space X is said to have the Tsirelson property if it does not contain subspaces that are isomorphic to l_{p}, p in [1,infty) or c_{0}. The article contains a quite simple method to producing Banach spaces with the Tsirelson property.

Wadim Zudilin

A new multiple-integral representation of a general family of very-well-poised hypergeometric series is proved. Inspite of an analytic character of the result, it is motivated by the recent arithmetic progress for the values of the Riemann zeta function at odd integers. The multiple integrals are of Euler-type and can be viewed as a natural generalization of

J. Gomez-Torrecillas, A. Louly

We investigate the relationship between coseparable and semisimple corings. In particular we prove that a coring over a separable algebra is coseparable if and only if it is absolutely semisimple.

Pirio luc

In this paper we study a functional equation associated to the Kummer&#39;s equation (K) of the trilogarithm. Then we apply our results to web geometry and to characterize the functions solution of (K).

Frederic Bayart

We study the existence of a common hypercyclic vector for different families of composition operators.

Daniele Guido, Tommaso Isola

The question whether an operator belongs to the domain of some singular trace is addressed, together with the dual question whether an operator does not belong to the domain of some singular trace. We show that the answers are positive in general, namely for any (compact, infinite rank) positive operator A we exhibit two singular traces, the first being zero

Maria Saprykina

We study the behavior of diffeomorphisms, contained in the closure $\bar {\A_\a}$ (in the inductive limit topology) of the set $\A_\a$ of real-analytic diffeomorphisms of the torus $\Bbb T^2$, conjugated to the rotation $R_\a:(x,y)\mapsto (x + \a, y)$ by an analytic measure-preserving transformation. We show that for a generic $\a\in [0,1]$, $\bar {\A_\a}$ c

Jack Spielberg

It is proved that classifiable simple separable nuclear purely infinite C*-algebras having finitely generated K-theory and torsion-free K_1 are semiprojective. This is accomplished by exhibiting these algebras as C*-algebras of infinite directed graphs.

Reza Abbaspur

Using the notion of a gauge connection on a flat superspace, we construct a general class of noncommutative ($D=2,$ $\mathcal{N}=1$) supertranslation algebras generalizing the ordinary algebra by inclusion of some new bosonic and fermionic operators. We interpret the new operators entering into the algebra as the generators of a U(1) (super) gauge symmery of

C. D. Fosco, L. E. Oxman, S. P. Sorella

We derive a general expression for the gauge invariant mass (m_G) for an Abelian gauge field, as induced by vacuum polarization, in 1+1 dimensions. From its relation to the chiral anomaly, we show that m_G has to satisfy a certain quantization condition. This quantization can be, on the other hand, explicitly verified by using the exact general expression fo

Alon E. Faraggi

The heterotic string free fermionic formulation produced a large class of three generation models, with an underlying SO(10) GUT symmetry which is broken directly at the string level by Wilson lines. A common subset of boundary condition basis vectors in these models is the NAHE set, which corresponds to Z2 X Z2 orbifold of an SO(12) Narain lattice, with (h1

Mina Aganagic, Marcos Marino, Cumrun Vafa

We demonstrate the equivalence of all loop closed topological string amplitudes on toric local Calabi-Yau threefolds with computations of certain knot invariants for Chern-Simons theory. We use this equivalence to compute the topological string amplitudes in certain cases to very high degree and to all genera. In particular we explicitly compute the topologi

Pavol Severa

We study a connection between duality and topological field theories. First, 2d Kramers-Wannier duality is formulated as a simple 3d topological claim (more or less Poincare duality), and a similar formulation is given for higher-dimensional cases. In this form they lead to simple TFTs with boundary coloured in two colours. The statistical models live on the

Nikita A. Nekrasov

Direct evaluation of the Seiberg-Witten prepotential is accomplished following the localization programme suggested some time ago. Our results agree with all low-instanton calculations available in the literature. We present a two-parameter generalization of the Seiberg-Witten prepotential, which is rather natural from the M-theory/five dimensional perspecti

D. Yu. Grigoriev, P. M. Sutcliffe, D. H. Tchrakian

We investigate multi-monopole solutions of a modified version of the BPS Yang-Mills-Higgs model in which a term quartic in the covariant derivatives of the Higgs field (a Skyrme term) is included in the Lagrangian. Using numerical methods we find that this modification leads to multi-monopole bound states. We compute axially symmetric monopoles up to charge

Tomas Ortin

The definition of ``Lie derivative&#39;&#39; of spinors with respect to Killing vectors is extended to all kinds of Lorentz tensors. This Lie-Lorentz derivative appears naturally in the commutator of two supersymmetry transformations generated by Killing spinors and vanishes for Vielbeins. It can be identified as the generator of the action of isometries on

V. Braun, B. Stefanski

Recently it has been shown that D-branes in orientifolds are not always described by equivariant Real K-theory. In this paper we define a previously unstudied twisted version of equivariant Real K-theory which gives the D-brane spectrum for such orientifolds. We find that equivariant Real K-theory can be twisted by elements of a generalised group cohomology.

Christopher P. Herzog, Igor R. Klebanov, Peter Ouyang

We review extensions of the AdS/CFT correspondence to gauge/ gravity dualities with N=1 supersymmetry. In particular, we describe the gauge/gravity dualities that emerge from placing D3-branes at the apex of the conifold. We consider first the conformal case, with discussions of chiral primary operators and wrapped D-branes. Next, we break the conformal symm

M. M. Block, G. Pancheri

The forward elastic scattering of light on light, {\em i.e.,} the reaction $γ+γ\to γ+γ$ in the forward direction, is analyzed utilizing real analytic amplitudes. We calculate $ρ_{γγ}$, the ratio of the real to the imaginary portion of the forward scattering amplitude, by fitting the total $γγ$ cross section data in the high energy region $5 GeV \le \sqrt s \

Thomas Becher

After contrasting the low energy effective theory for the baryon sector with one for the Goldstone sector, I use the example of pion nucleon scattering to discuss some of the progress and open issues in baryon chiral perturbation theory.

G. L. Fogli, E. Lisi, A. Marrone, D. Montanino

(Abridged.) We present a thorough analysis of the current solar neutrino data, in the context of two-flavor active neutrino oscillations. We aim at performing an accurate and exhaustive statistical treatment of both the input and the output information. Concerning the input, we analyze 81 observables, including the Cl rate, the total Ga rate and its winter-s

C. J. Burden, M. A. Pichowsky

Masses for vector 1--, axialvector 1+-, 1++, and exotic-vector 1-+ mesons are calculated within a quantum field theoretic framework based on the Dyson-Schwinger equations using a model form of the quark-antiquark interaction that is separable. The model provides an excellent description of pion and K-meson observables and the flavor-octet ground-state meson

A. Mukherjee, M. Vanderhaeghen

We investigate the off-forward matrix element of the light cone vector operator for a dressed quark state in light-front Hamiltonian perturbation theory. We obtain the corresponding splitting functions in a straightforward way. We show that the end point singularity is canceled by the contribution from the normalization of state. Considering mixing with the

Jing-Wu Li, Mao-Zhi Yang, Dong-Sheng Du

We employ one-particle-exchange method to study D-->PV decays in D-->K ρ, πK*, πρprocesses. Taking into account a strong phase and considering nonfactorizable effect, we can get good results consistent with the experimental data. Nonfactorizable effect is not always large, but in some cases, the nonfactorizable effect is nececcesary to accommodate the experi

S. Nandi, T. Torma

The mixing of the Standard Model Higgs boson with a ttbar scalar bound state (arising from a new stronger-than-QCD interaction) can enhance the Higgs boson&#39;s coupling to two gluons. It is possible that the two-gluon decay mode of a light Higgs boson may even dominate. This alters the Higgs boson search strategy at Tevatron Run 2 in a significant way. We

Adriano Di Giacomo

It is proven that dual superconductivity of QCD vacuum in the confining phase is an intinsic property, independent on the choice of the abelian projection used to define the monopoles.

J. Kroseberg

Selected recent ZEUS and H1 results on open charm and beauty production in high energy ep collisions are reviewed. Measurements of differential D* cross sections, charm meson production ratios and semi-leptonic beauty decays are discussed and compared with QCD predictions.

B. J. Kim, T. Iwashita, T. Ishida, E. J. Jeon

The K2K long-baseline neutrino oscillation experiment uses a Scintillating Fiber Detector (SciFi) to reconstruct charged particles produced in neutrino interactions in the near detector. We describe the track reconstruction algorithm and the performance of the SciFi after three years of operation.

D. V. Bandurin, N. B. Skachkov

Since a lot of theoretical predictions on the production of new particles (Higgs, SUSY) at the Tevatron are based on model estimations of the proton gluon density behavior at low $x$ and high values of a transfered momentum Q^2, the study of a possibility of a measurement of the gluon density in this kinematic region directly in Tevatron experiments is obvio

Martin Bojowald

Quantum geometry predicts that a universe evolves through an inflationary phase at small volume before exiting gracefully into a standard Friedmann phase. This does not require the introduction of additional matter fields with ad hoc potentials; rather, it occurs because of a quantum gravity modification of the kinetic part of ordinary matter Hamiltonians. A

Martin Bojowald

Some typical quantization ambiguities of quantum geometry are studied within isotropic models. Since this allows explicit computations of operators and their spectra, one can investigate the effects of ambiguities in a quantitative manner. It is shown that those ambiguities do not affect the fate of the classical singularity, demonstrating that the absence o

J. A. Valiente Kroon

Using a representation of spatial infinity based in the properties of conformal geodesics, the first terms of an expansion for the Bondi mass for the development of time symmetric, conformally flat initial data are calculated. As it is to be expected, the Bondi mass agrees with the ADM at the sets where null infinity ``touches&#39;&#39; spatial infinity. The