July 1996 arXiv papers — page 3

Louis Crane, David N. Yetter

We construct tensor and bitensor categories with given Grothedieck rig (fusion algebra) in simple cases. The results provide examples on which to test the conjectural construction of 4-D TQFT's proposed by Crane and Frenkel and shed light on several other constructions of TQFT's.

Damiano Anselmi

Certain topological invariants of the moduli space of gravitational instantons are defined and studied. Several amplitudes of two and four dimensional topological gravity are computed. A notion of puncture in four dimensions, that is particularly meaningful in the class of Weyl instantons, is introduced. The topological embedding, a theoretical framework for

Nicolas Roy

We dicuss the resolution of initial value problems of electrodynamics in the Lorentz gauge.

Savas Dimopoulos, Michael Dine, Stuart Raby, Scott Thomas

The experimental signatures for low energy supersymmetry breaking are presented. The lightest standard model superpartner is unstable and decays to its partner plus a Goldstino, $G$. For a supersymmetry breaking scale below a few 1000 TeV this decay can take place within a detector, leading to very distinctive signatures. If a neutralino is the lightest stan

Alan Kostelecky, Rick Van Kooten

The feasibility of placing bounds on CPT violation from experiments with neutral-$B$ mesons is examined. We consider situations with uncorrelated mesons and ones with either unboosted or boosted correlated mesons. Analytical expressions valid for small T- and CPT-violating parameters are presented for time-dependent and time-integrated decay rates, and vario

Tamas G. Kovacs, E. T. Tomboulis

We report on further progress in our programme of understanding confinement in 3d and 4d SU(2) gauge theory in terms of Z(2) monopoles. A sufficient condition for confinement was previously translated into Z(2) monopole correlation inequalities in a related SO(3) gauge theory. We shall discuss the physical picture underlying this scenario and present some Mo

Carlo Carraro

The idea of charge frustration is applied to describe the properties of such diverse physical systems as oil-water-surfactant mixtures and metal-ammonia solutions. The minimalist charge-frustrated model possesses one energy scale and two length scales. For oil-water-surfactant mixtures, these parameters have been determined starting from the microscopic prop

Hsi-Sheng Goan, Victor M. Yakovenko

The Hall conductivity in the magnetic-field-induced spin-density-wave (FISDW) state of the quasi-one-dimensional organic conductors (TMTSF)$_2$X at a finite temperature is calculated. The temperature dependence of the Hall conductivity is found to be the same as the temperature dependence of the Fröhlich current of a regular charge/spin-density wave. Predict

Jochen Rau

In close analogy to the Bloch-Feshbach formalism known from the theory of nuclear dynamics, I develop a mathematical framework that allows one to understand renormalization in terms of purely algebraic operations (projections, dilatations) in Hilbert space. This algebraic approach is put to the test in the study of the low-energy dynamics of interacting quan

James G. McLean, B. Krishnamachari, D. R. Peale, E. Chason

A theory based on the thermodynamic Gibbs-Thomson relation is presented which provides the framework for understanding the time evolution of isolated nanoscale features (i.e., islands and pits) on surfaces. Two limiting cases are predicted, in which either diffusion or interface transfer is the limiting process. These cases correspond to similar regimes cons

Jogesh C. Pati

The paper addresses the problem of suppressing naturally the unsafe d=4 as well as the color-triplet mediated and/or gravity-linked d=5 proton-decay operators, which generically arise in SUSY-unification. It also attempts to give light masses to the neutrinos, of the type suggested by current experiments. It is noted that neither the symmetries in $SO(10)$,

Bruce Allen, Adrian C. Ottewill

By correlating the signals from a pair of gravitational-wave detectors, one can undertake sensitive searches for a stochastic background of gravitational radiation. If the stochastic background is anisotropic, then this correlated signal varies harmonically with the earth's rotation. We calculate how the harmonics of this varying signal are related to the mu

D. Shubashree, R. Shankar

We analyse a family of models, that interpolates between the Triangular lattice antiferromagnet (TLAF) and the Kagome lattice antiferromagnet (KLAF). We identify the field theories governing the low energy, long wavelength physics of these models. Near the TLAF the low energy field theory is a nonlinear sigma model of a SO(3) group valued field. The SO(3) sy

Jiro Arafune, Joe Sato

We examine how large violation of CP and T is allowed in long base line neutrino experiments. When we attribute only the atmospheric neutrino anomaly to neutrino oscillation we may have large CP violation effect. When we attribute both the atmospheric neutrino anomaly and the solar neutrino deficit to neutrino oscillation we may have a sizable T violation ef

F. B. Anders, K. Gloos

The bias-dependent resistance R(V) of NS-junctions is calculated using the Keldysh formalism in all orders of the transfer matrix element. We present a compact and simple formula for the Andreev current, that results from the coupling of electrons and holes on the normal side via the anomalous Green's function on the superconducting side. Using simple BC

A. Schönenberger, A. Larkin, E. Heeb, V. Geshkenbein

We investigate numerically the dynamically generated plastic deformations of a 3D vortex lattice (VL) driven through a disorder potential with isolated, strong pinning centers (point-like or extended along the field direction). We find that the VL exhibits a very peculiar dynamical behavior in the plastic flow regime, in particular, topological excitations c

Lev Vaidman

Various quantum measurement procedures are analyzed and it is shown that under certain conditions they yield consistently {\em weak values} which might be very different from the eigenvalues, the allowed outcomes according to the standard quantum formalism. The weak value outcomes result from peculiar quantum interference of the pointer variable of the measu

C. Brif, A. Vourdas, A. Mann

We consider two analytic representations of the SU(1,1) Lie group: the representation in the unit disk based on the SU(1,1) Perelomov coherent states and the Barut-Girardello representation based on the eigenstates of the SU(1,1) lowering generator. We show that these representations are related through a Laplace transform. A ``weak'' resolution of t

P. Buechel, M. Luecke, D. Roth, R. Schmitz

A unique pattern selection in the absolutely unstable regime of a driven, nonlinear, open-flow system is analyzed: The spatiotemporal structures of rotationally symmetric vortices that propagate downstream in the annulus of the rotating Taylor-Couette system due to an externally imposed axial through-flow are investigated for two different axial boundary con

H. W. Fearing, S. Scherer

We discuss the low-energy behavior of the virtual Compton scattering amplitude off a spin-zero target. We first compare various methods of obtaining a low-energy expression based either on the soft-photon approximation or the use of Ward-Takahashi identities. We point out that structure-dependent terms are defined with respect to a low-energy approximation o

H. -J. Schulze, D. Blaschke

We compare the recent CERES data on dielectron production in 200 GeV/u S+Au collisions with the theoretical predictions due to pion annihilation in a thermal hadronization and a string fragmentation scenario. Both models yield similar results for the dilepton mass spectrum. A satisfactory description of the experimental spectrum requires an in-medium reducti

D. Kiderlen, V. M. Kolomietz, S. Shlomo

Within the nuclear Fermi-liquid drop model, quantum and thermal fluctuations are considered by use of the Landau-Vlasov-Langevin equation. The spectral correlation function of the nuclear surface fluctuations is evaluated in a simple model of an incompressible and irrotational Fermi liquid. The dependence of the spectral correlation function on the dynamical

K. Hagino, N. Takigawa, M. Dasgupta, D. J. Hinde

The role of higher order coupling of surface vibrations to the relative motion in heavy-ion fusion reactions at near-barrier energies is investigated. The coupled channels equations are solved to all orders, and also in the linear and the quadratic coupling approximations. Taking $^{64}$Ni + $^{92,96}$Zr reactions as examples, it is shown that all order coup

E. G. Lanza, M. V. Andres, F. Catara, Ph. Chomaz

Using a microscopic approach beyond RPA to treat anharmonicities, we mix two-phonon states among themselves and with one-phonon states. We also introduce non-linear terms in the external field. These non-linear terms and the anharmonicities are not taken into account in the "standard" multiphonon picture. Within this framework we calculate Coulomb ex

G. Chanfray

We discuss various aspects of pion physics in the nuclear medium. We first study s-wave pion-nucleus interaction in connection with chiral symmetry restoration and quark condensate in the nuclear medium. We then adress the question of p-wave pion-nucleus interaction and collective pionic modes in nuclei and draw the consequences for in medium $ππ$ correlatio

Charles B. Thorn

I review work developing the idea that string is a composite of point-like entities called string bits. Old and new insights this picture brings into the nature of string theory are discussed. This paper summarizes my talk presented to the Strings96 conference at Santa Barbara, CA, 14-20 July 1996.

F. De Jonghe, K. Peeters, K. Sfetsos

The presence of Killing-Yano tensors implies the existence of non-standard supersymmetries in point particle theories on curved backgrounds. In a string theoretical context these are symmetries of the modes describing the particle-like behavior of the string. In the presence of isometries we show that, in addition to these, one can also define a new type of

N. Dorey, V. V. Khoze, M. Mattis

We further discuss the N=2 superinstantons in SU(2) gauge theory, obtained from the general self-dual solutions of topological charge n constructed by Atiyah, Drinfeld, Hitchin and Manin (ADHM). We realize the N=2 supersymmetry algebra as actions on the superinstanton moduli. This allows us to recast in concise superfield notation our previously obtained exp

Gerhard Buchalla, Andrzej J. Buras

We investigate the future determination of the CKM matrix using theoretically clean quantities, like $B(K^+\toπ^+ν\barν)$, $B(K_L\toπ^0ν\barν)$ or $\sin 2β$, $\sin 2α$ as extracted from CP violation studies in $B$ physics. The theoretical status of $K\toπν\barν$ is briefly reviewed and their phenomenological potential is compared with that of CP asymmetries

Andrei Afanasev, W. W. Buck

A calculation of the semi--leptonic decays of the kaon ($K_{l3}$) is presented. The results are direct predictions of a covariant model of the pion and kaon introduced earlier by Ito, Buck, Gross. The weak form factors for $K_{l3}$ are predicted with absolutely no parameter adjustments of the model. We obtained for the form factor parameters: $f_-(q^2=m_l^2)

Joao P Silva

A brief review of the strategies used in looking for CP violation in B decays is presented. Some problems due to penguin diagrams are addressed. Penguin trapping is discussed, in the context of the upcoming experiments. The high rates and the possibility to perform experiments on the $B_s$ system justify the interest in hadronic colliders.

Lev A. Koyrakh

A model independent approach based on a generalization of the operator product expansion is used to describe semileptonic decays of heavy flavors. In the first part of the dissertation we calculate differential distributions in the inclusive semileptonic weak decays of heavy flavors in QCD. In particular, the double distribution in electron energy and invari

L. E. Gordon, W. Vogelsang

We present a NLO study of inclusive polarized prompt photon production in a conceivable fixed target $pp$ mode of HERA with longitudinally polarized protons at $\sqrt{s}=39$ GeV. We analyze the sensitivity of the corresponding double spin asymmetry to the proton's polarized gluon distribution $Δg$ and estimate the expected statistical precision in its de

B. R. Webber

Recent developments in theory and phenomenology relevant to deep inelastic lepton scattering are reviewed, concentrating on the following topics: Predicted behaviour of non-singlet and polarized structure functions at small $x$; Theoretical studies of saturation and unitarity effects at small $x$ in quarkonium scattering; Renormalons and higher twist contrib

B. G. Zakharov

For the first time a rigorous quantum treatment of the Landau-Pomeranchuk-Migdal effect in QED and QCD is given. The rate of photon (gluon) radiation by an electron (quark) in medium is expressed through the Green's function of a two-dimensional Schrödinger equation with an imaginary potential. In QED this potential is proportional to the dipole cross se

Hoang Ngoc Long

A model based on the $\mbox{SU(3)}_L\otimes \mbox{U(1)}_N$ gauge group, in which neutrinos have right-handed neutral currents is considered. We argue that in order to have a result consistent with low-energy one, the right-handed neutrino component must be treated as correction instead of an equivalent spin state.

G. M. de Divitiis, R. Frezzotti, M. Masetti, R. Petronzio

We study dynamical fermion effects in lattice QCD at finite temperature. The method adopted is basically the extrapolation from negative flavour numbers already tested at zero temperature and based on the simulation of local bosonic theories, with an essential difference. With an appropriate choice of the boundary conditions on the bosonic fields, called ``b

Massimo Campostrini, Paolo Rossi, Andrea Pelissetto, Ettore Vicari

We present new strong-coupling series for O(N) spin models in three dimensions, on the cubic and diamond lattices. We analyze these series to investigate the two-point Green's function G(x) in the critical region of the symmetric phase. This analysis shows that the low-momentum behavior of G(x) is essentially Gaussian for all N from zero to infinity. Thi

B. Alles, M. D'Elia, A. Di Giacomo

We present a measurement of the topological susceptibility in SU(3) Yang-Mills theory through the deconfinement phase transition. An improved operator is used for the topological charge density. A drop by an order of magnitude is observed from the confined to the deconfined phase.

John D. Stack

We present results from magnetic monopoles in $SU(2)$ lattice gauge theory at finite temperature. The lattices are $16^{3}\times N_{t}$, for $N_{t}=4,6,8,12$, at $β=2.5115$. Quantities discussed are: the spacial string tension, Polyakov loops, and the screening of timelike and spacelike magnetic currents.

M. Gürtler, E. -M. Ilgenfritz, J. Kripfganz, H. Perlt

Physical parameters of the electroweak phase transition in a 3d effective lattice SU(2)-Higgs model are presented. The phase transition temperatures, latent heats and continuum condensate discontinuities are measured at Higgs masses of about 70 and 35 GeV. Masses and Higgs condensates are compared to perturbation theory in the broken phase. In the symmetric

M. Gürtler, E. -M. Ilgenfritz, J. Kripfganz, H. Perlt

We study the electroweak phase transition in an effective 3-dimensional theory for a Higgs mass of about 70 GeV by Monte Carlo simulations. The transition temperature and jumps of order parameters are obtained and extrapolated to the continuum using multi-histogram techniques and finite size analysis.

Paolo Rossi, Ettore Vicari

The possibility of removing the one-loop perturbative effects of lattice artifacts by a proper choice of the lattice action is explored, and found to depend crucially on the properties of the physical quantity considered. In this respect the finite-space-volume mass gap m(L) is an improved observable. We find an explicit momentum space representation of the

M. Rainer

For a canonical formulation of quantum gravity, the superspace of all possible 3-geometries on a Cauchy hypersurface of a 3+1-dimensional Lorentzian manifold plays a key role. While in the analogous 2+1-dimensional case the superspace of all Riemannian 2-geometries is well known, the structure of the superspace of all Riemannian 3-geometries has not yet been

A. Tiemblo, R. Tresguerres

We present a gauge--theoretical derivation of the notion of time, suitable to describe the Hamiltonian time evolution of gravitational systems. It is based on a nonlinear coset realization of the Poincaré group, implying the time component of the coframe to be invariant, and thus to represent a metric time. The unitary gauge fixing of the boosts gives rise t

J. Madore

A review is made of recent efforts to define linear connections and their corresponding curvature within the context of noncommutative geometry. As an application it is suggested that it is possible to identify the gravitational field as a phenomenological manifestation of space-time commutation relations and to thereby clarify its role as an ultraviolet reg

Kay Joerg Wiese, Francois David

The scaling properties of self-avoiding polymerized 2-dimensional membranes are studied via renormalization group methods based on a multilocal operator product expansion. The renormalization group functions are calculated to second order. This yields the scaling exponent nu to order epsilon^2. Our extrapolations for nu agree with the Gaussian variational es

C. de C. Chamon, D. E. Freed, S. A. Kivelson, S. L. Sondhi

We propose a device, consisting of a Hall bar with two weak barriers, that can be used to study quantum interference effects in a strongly correlated system. We show how the device provides a way of measuring the fractional charge and fractional statistics of quasiparticles in the quantum Hall effect through an anomalous Aharanov-Bohm period. We discuss how

Y. Anusooya, Swapan K Pati, S. Ramasesha

The phase diagram of halogen-bridged mixed-valent metal complexes ($MX$) has been studied using a two-band extended Peierls-Hubbard model employing the recently developed Density Matrix Renormalization Group method. We present the energies, charge and spin density distributions, bond orders, charge-charge and spin-spin correlations, in the ground state for d

Kay Joerg Wiese

A complete classification of the renormalization-group flow is given for impurity-like marginal operators of membranes whose elastic stress scales like (Δr)^2 around the external critical dimension d_c=2. These operators are classified by characteristic functions on R^2 x R^2.

Carlos Gonzalez-Buxton, Kevin Ingersent

Perturbative scaling is applied to the Anderson model for a localized level coupled to a Fermi system in which the density of states varies like $|E|^r$ near the Fermi energy ($E=0$). This model with $r=1$ or $2$ may describe magnetic impurities in unconventional superconductors and certain semiconductors. The pseudo-gap is found to suppress mixed valence in

Bruce C. Paul, Kevin Ingersent

A Kondo model for three spin-one-half impurities placed at the vertices of an equilateral triangle is studied using the numerical renormalization-group method. The impurity spins can form two frustrated doublets which, because of the rotation symmetry, couple equally to the conduction band. Over a broad range of antiferromagnetic RKKY interaction strengths,

Masahito Ueda

A real-time functional-integral method is used to derive an effective action that gives the transmission spectrum of a tunneling particle interacting with a bath of harmonic oscillators. The transmission spectum is expressed in terms of double functional integrals with respect to the coordinate of the particle which are evaluated by means of stationary-phase

M. Bijlsma, H. T. C. Stoof

We study the three-dimensional atomic Bose gas using renormalization group techniques. Using our knowledge of the microscopic details of the interatomic interaction, we determine the correct initial values of our renormalization group equations and thus obtain also information on nonuniversal properties. As a result, we can predict for instance the critical

Claudio Castellano, Marco Zannetti

The influence of the initial fluctuations on the onset of scaling in the quench to zero temperature of a two dimensional system with conserved order parameter, is analyzed in detail with and without topological defects. We find that the initial fluctuations greatly affect the way scaling is reached, while the number of components of the order parameter does

M. E. Ferrero, G. Parisi, P. Ranieri

We discuss Gaussian fluctuations in a spin glass model with one replica symmetry breaking. We show how non-perturbative fluctuations of the break-point parameter can be included in the longitudinal propagator within linear response theory.

H. Hiramoto, Mahito Kohmoto

We study the classical vibration problem of a chain with spring constants which are modulated in a quasiperiodic manner, {\it i. e.}, a model in which the elastic energy is $\sum_j k_j( u_{j-1}-{u_j})^2$, where $k_j=1+Δcos[2πσ(j-1/2)+θ]$ and $σ$ is an irrational number. For $Δ< 1$, it is shown analytically that the spectrum is absolutely continuous, {\it i.e

Yorick Wilks, Mark Stevenson

This squib claims that Large-scale Automatic Sense Tagging of text (LAST) can be done at a high-level of accuracy and with far less complexity and computational effort than has been believed until now. Moreover, it can be done for all open class words, and not just carefully selected opposed pairs as in some recent work. We describe two experiments: one expl

Ilyas Cicekli, H. Altay Guvenir

This paper proposes a mechanism for learning pattern correspondences between two languages from a corpus of translated sentence pairs. The proposed mechanism uses analogical reasoning between two translations. Given a pair of translations, the similar parts of the sentences in the source language must correspond the similar parts of the sentences in the targ

Gregory L. Eyink, Francis J. Alexander

General turbulent mean statistics are shown to be characterized by a variational principle. The variational functionals, or ``effective actions&#39;&#39;, have experimental consequences for turbulence fluctuations and are subject to realizability conditions of positivity and convexity. An efficient Rayleigh-Ritz algorithm is available to calculate approximat

Jeff Secker, Paul S. Wesson, James R. Lepock

We have carried out a series of calculations involving bacteria and viruses embedded in dust grains, which are ejected from our solar system by radiation pressure, and travel through space to other star systems. Under many conditions, this kind of panspermia is impractical, primarily because the ultraviolet (UV) radiation of the present Sun inactivates the m

M. Valluri, G. C. Anupama

We report results of a search for optical emission line gas in the Hickson compact group 62. From narrow band (H-alpha) imaging observations we estimate 10^4 Msun of ionized hydrogen gas within the central regions of three of the galaxies in the group. There has been considerable interest in this group since ROSAT detected an extended halo of diffuse X-ray e

John H. Schwarz

These lectures begin by reviewing the evidence for S duality of the toroidally compactified heterotic string in 4d that was obtained in the period 1992--94. Next they review recently discovered dualities that relate all five of the 10d superstring theories and a quantum extension of 11d supergravity called M theory. The study of p-branes of various dimension

Hua-Bin Tang

I propose a prescription for separating the high- and low-energy contributions in effective field theories. This prescription allows a relativistic treatment of matter fields in chiral perturbation theory while the power counting remains valid.

Carlo Carraro, David R. Nelson

We study the statistical mechanics and dynamics of crystalline films with a fixed internal connectivity on a random substrate. Defect free triangular lattices exhibit a sharp transition to a low temperature glassy phase with anomalous phonon fluctuations and a nonlinear force-displacement law with a continuously variable exponent, similar to the vortex glass

Patrick Huet

I address the phenomenology of CPT violation in the neutral kaon system under the assumption that it originates from Planck scale physics. This assumption opens the door to a new set of CPT violating parameters whose phenomenology is distinct from the $Δ$ parameter usually considered in the Hamiltonian. The origin of these parameters reflects a possible depa

B. Borasoy, Ulf-G. Meißner

We analyze the octet baryon masses and the pion/kaon--nucleon $σ$--terms in the framework of heavy baryon chiral perturbation theory. We include {\it all} terms up-to-and-including quadratic order in the light quark masses, $m_q$. We develop a consistent scheme to estimate low--energy constants related to scalar--isoscalar operators in the framework of reson

Nalini Joshi

The first discrete Painlevé equation (dPI), which appears in a model of quantum gravity, is an integrable nonlinear nonautonomous difference equation which yields the well known first Painlevé equation (PI) in a continuum limit. The asymptotic study of its solutions as the discrete time-step $n\to\infty$ is important both for physical application and for che

Max Tegmark

To quantify the effect of decoherence in quantum measurements, it is desirable to measure not merely the square modulus of the spatial wavefunction, but the entire density matrix, whose phases carry information about momentum and how pure the state is. An experimental setup is presented which can measure the density matrix (or equivalently, the Wigner functi

A. Metz, D. Drechsel

Virtual Compton scattering off the nucleon has been studied in the one-loop approximation of the linear sigma model. The three generalized polarizabilities of the nucleon have been calculated and compared with the existing theoretical predictions. In particular, we find that only two of the three scalar polarizabilities are independent observables.

Peter Cho, Per Kraus

We investigate the confining phase vacua of supersymmetric $Sp(2\NC)$ gauge theories that contain matter in both fundamental and antisymmetric representations. The moduli spaces of such models with $\NF=3$ quark flavors and $\NA=1$ antisymmetric field are analogous to that of SUSY QCD with $\NF=\NC+1$ flavors. In particular, the forms of their quantum superp

R. Banerjee

A gauge independent method of obtaining the reduced space of constrained dynamical systems is discussed in a purely lagrangian formalism. Implications of gauge fixing are also considered.

Jacek Pawełczyk

New rigid string instanton equations are derived. Contrary to standard case, the equations split into three families. Their solutions in $R^4$ are discussed and explicitly presented in some cases.

Giampiero Esposito

This paper studies the 1-loop approximation for a massless spin-1/2 field on a flat four-dimensional Euclidean background bounded by two concentric 3-spheres, when non-local boundary conditions of the spectral type are imposed. The use of $ζ$-function regularization shows that the conformal anomaly vanishes, as in the case when the same field is subject to l

Sergiu I. Vacaru

A general approach to formulation of supergravity in higher order anisotropic superspaces (containing as particular cases different supersymmetric extensions and prolongations of Riemann, Finsler, Lagrange and Kaluza--Klein spaces) is given. We analyze three models of locally anisotropic supergravity.

Sergiu I. Vacaru

Torsions, curvatures, structure equations and Bianchi identities for locally anisotropic superspaces (containing as particular cases different supersymmetric extensions and prolongations of Riemann, Finsler, Lagrange and Kaluza--Klein spaces) are investigated.

Sergiu I. Vacaru

Higher order anisotropic superspaces are constructed as generalized vector superbundles provided with compatible nonlinear connection, distinguished connection and metric structures.

Jose F. Morales, Marco Serone

We study a special class of higher derivative F-terms of the form $F_{g,n}W^{2g}(Πf)^{n}$ where W is the N=2 gravitational superfield and $Π$ is the chiral projector applied to a non-holomorphic function $f$ of the heterotic dilaton vector superfield. We analyze these couplings in the heterotic theory on $K3\times T^2$ , where it is found they satisfy an ano

I. J. R. Aitchison, G. Amelino-Camelia, M. Klein-Kreisler, N. E. Mavromatos

We show that the gauge-fermion interaction in multiflavour $(2+1)$-dimensional quantum electrodynamics with a finite infrared cut-off is responsible for non-fermi liquid behaviour in the infrared, in the sense of leading to the existence of a non-trivial fixed point at zero momentum, as well as to a significant slowing down of the running of the coupling at

Luca Lusanna

A review is given of the canonical reduction of gauge and relativistic particle theories and of a new covariant rest-frame instant form of dynamics according to Dirac&#39;s theory of constraints

M. Maul, A. Schäfer

We investigate the possibility to measure the spin content carried by the different quark flavors in a nucleon by means of polarized deep inelastic scattering with $W^\pm$ exchange at HERA. Such measurements require a polarized proton beam. The expected inclusive and semi inclusive asymmetries are sizable and for realistic luminosities the expected statistic

John Ellis, N. E. Mavromatos, D. V. Nanopoulos

We discuss the possibility that CPT violation may appear as a consequence of microscopic decoherence due to quantum-gravity effects, that we describe using a density-matrix formalism motivated by our studies of non-critical string theory. The maximum possible order of magnitude of such decohering CPT-violating effects is not far from the sensitivity of prese

John N. Bahcall, E. Lisi

We analyze tests of electron flavor conservation that can be performed at the Sudbury Neutrino Observatory (SNO). These tests, which utilize $^8$B solar neutrinos interacting with deuterium, measure: 1) the shape of the recoil electron spectrum in charged-current (CC) interactions (the CC spectrum shape); and 2) the ratio of the number of charged current to

F. Klingl, N. Kaiser, W. Weise

An improved update of the structure and decays of $ρ^0$, $ω$ and $ϕ$ mesons based on a chiral SU(3) Lagrangian, including anomaly terms is presented. We demonstrate that a consistent and quantitatively successful description of both pion and kaon electromagnetic form factors can be achieved. We also discuss the $e^+e^- \to π^+ π^0 π^-$ cross section, the Dal

P. Nason

I discuss the effect of resummation of soft gluons in hadronic production of high mass systems, and in particular in heavy flavour production. I show that in widely used $x$-space resummation formulae, spurious terms that grow factorially in the order of the perturbative expansion are present. These terms spoil the convergence of the perturbative expansion.

Paul Singer

We survey the possibilities of detecting the $s \rightarrow d γ$ transition in kaon and hyperon radiative decays. In the more frequent decays, like $K^+ \rightarrow π^+ π^o γ$, $K^+ \rightarrow π^+ \ell^+ \ell^-$, the short-distance contribution is obscured by various long-distance transitions. Among the hyperon radiative decays, $Ξ^- \rightarrow Σ^- γ$ and

V. Bernard, N. Kaiser, Ulf-G. Meißner

We investigate the imaginary parts of the nucleon electromagnetic and axial form factors close to threshold in the framework of heavy baryon chiral perturbation theory. For the isovector electromagnetic form factors, we recover the well known strong enhancement near threshold. For the isoscalar ones, we show that there is no visible enhancement due to the th

M. Anselmino, P. Gambino, J. Kalinowski

Estimates for longitudinal spin asymmetries which single out new polarized nucleon structure functions in deeply inelastic charged current interactions at HERA energies are given, exploiting their interpretation in terms of polarized quark distributions. These asymmetries turn out to be large and allow a measurement of the new polarized structure functions $

A. L. Kataev

We summarize the current status of our understanding of the structure of the perturbative QCD expressions for the QCD generalization of the Crewther relation.

G. V. Efimov

The mechanism of formation of bound states in the relativistic quantum field theory is demonstrated by the Yukawa field model. It is shown that the weak coupling regime leads to the potential picture, i.e. it is equivalent to the nonrelativistic limit in the bound state problem. In the strong coupling regime the potential picture is not valid and the method

G. V. Efimov, S. N. Nedelko

It is shown that an (anti-)self-dual homogeneous vacuum gluon field appears in a natural way within the problem of calculation of the QCD partition function in the form of Euclidean functional integral with periodic boundary conditions. There is no violation of cluster property within this formulation, nor are parity, color and rotational symmetries broken e

Francesco Vissani

We present the study of the possibility to have R-parity breaking interactions in minimal SU(5). An interesting scenario emerges in which the R-parity breaking coupling $λ&#39;_{333}$ is large, and its size is related to the value of the tau neutrino mass, assuming that supersymmetry is broken according to low energy supergravity framework. This scenario may

K. G. Chetyrkin, J. H. Kühn, M. Steinhauser

We present analytical calculation of the first seven moments of the heavy quark vacuum polarization function in the three-loop order. The obtained results are compared against the asymptotic formulas following from the threshold singularities. We also discuss the $μ$ dependence of the moments within the BLM procedure.

M. A. Stephanov

The behavior of quenched QCD at nonzero chemical potential $μ$ has been a long-standing puzzle. An explicit solution is found using the random matrix approach to chiral symmetry breaking. At nonzero $μ$ the quenched QCD is not a simple $n\to0$ limit of a theory with $n$ quarks: a naive `replica trick&#39; fails. A limit that leads to the quenched QCD is that

Randy Lewis, R. M. Woloshyn

The rho meson decay constant and the associated renormalization factor are computed in the quenched approximation on coarse lattices using a tadpole-improved action which is corrected at the classical level to O(a^2). The improvement is displayed by comparing to Wilson action calculations.

H. R. Fiebig, R. M. Woloshyn

Meson and baryon masses in the light (u,d and s) sector are calculated using tadpole-improved gauge field and fermion actions. These are corrected to order $O(a^2)$ on the classical level using next-nearest-neighbour terms. The results, obtained at lattice spacings of 0.4 and 0.27fm, are compared to Wilson action calculations.

K. Jansen, C. Liu

We study the question of lack of reversibility and the chaotic nature of the equations of motion in numerical simulations of lattice QCD.

Jen-Fa Min, Huei-Shih Liao

Based on an analytical technique using a unitary transformation and the variational method, we study the chiral order parameter in the Schwinger model in the lattice formalism with Kogut-Susskind fermions. The fermion condensate $\langle {\barΨ} Ψ\rangle $ for any coupling constant and fermion mass are calculated. Chiral symmetry is shown to be broken in the

Nils Andersson

We consider the initial value problem for a massless scalar field in the Schwarzschild geometry. When constructed using a complex-frequency approach the necessary Green&#39;s function splits into three components. We discuss all of these in some detail: 1) The contribution from the singularities (the quasinormal modes of the black hole) is approximated and t

J. P. Rodriguez

The classical ferromagnet is analyzed in two dimensions via a mean-field treatment of the CP$^1$ model valid in the limit of low temperature and of weak magnetic field. At high skyrmion densities, we find that the magnetization begins to decrease linearly with temperature, but it then crosses over to a Curie-law at higher temperature. The comparison of these