September 1996 arXiv papers — page 9

N. Bulut, D. J. Scalapino

Superconductivity has been recently observed in Sr_{0.4}Ca_{13.6}Cu_{24}O_{41.84} which contains quasi-one-dimensional Cu_{2}O_{3} 2-leg ladders. If, as suggested by some theories, the superconductivity arises from these 2-leg ladders, it will be important to determine the structure of the superconducting gap. In particular, does the gap in a 2-leg ladder ch

Martin R. Zirnbauer

A generalized Hubbard-Stratonovitch transformation relating an integral over random unitary N times N matrices to an integral over Efetov's unitary sigma model manifold, is introduced. This transformation adapts the supersymmetry method to disordered and chaotic systems that are modeled not by a Hamiltonian but by their scattering matrix or time-evolutio

A. J. S. Hamilton, R. A. Fesen, C. -C. Wu, D. M. Crenshaw

We present a theoretical interpretation of the broad silicon and iron UV absorption features observed with the Hubble Space Telescope in the spectrum of the Schweizer-Middleditch star behind the remnant of Supernova 1006. These features are caused by supernova ejecta in SN1006. We propose that the redshifted SiII2 1260 A feature consists of both unshocked an

A. Gathmann

We study Gromov-Witten invariants on the blow-up of P^n at a point, which is probably the simplest example of a variety whose moduli spaces of stable maps do not have the expected dimension. It is shown that many of these invariants can be interpreted geometrically on P^n as certain numbers of rational curves having a multiple point of given order at the blo

C. Pagani, G. Bellomo, P. Pierini

A proposal for a 10-120 mA proton linac employing superconducting beta-graded, CERN type, four cell cavities at 352 MHz is presented. The high energy part (100 MeV-1 GeV) of the machine is split in three beta-graded sections, and transverse focusing is provided via a periodic doublet array. All the parameters, like power in the couplers and accelerating fiel

Mou Roy

The violation of the equivalence principle (VEP) causing neutrino oscillations is of current interest. We study here the possibility of not only flavor oscillation but spin flavor oscillation of ultra high energy ($ \sim$ 1 PeV) neutrinos emanating from AGN due to VEP and due to the presence of a large magnetic field ($ \sim$ 1 Tesla) in AGN. In particular w

Gene F. Mazenko

An explicit expression for the vortex velocity field as a function of the order parameter field is derived for the case of point defects in the O(n) symmetric time-dependent Ginzburg-Landau model. This expression is used to find the vortex velocity probability distribution in the gaussian closure approximation in the case of phase ordering kinetics for a non

Jeong-Man Park

We consider the tilted-hexatic Hamiltonian on the fluctuating membranes. A renormalization-group analysis leads us to find two critical regions; one corresponds to the strong coupling regime of the gradient cross coupling, the other to the weak coupling regime. In the strong coupling regime, we find the locked tilted-hexatic to liquid phase transition when d

Marco Bruni, Sabino Matarrese, Silvia Mollerach, Sebastiano Sonego

We consider in detail the problem of gauge dependence that exists in relativistic perturbation theory, going beyond the linear approximation and treating second and higher order perturbations. We first derive some mathematical results concerning the Taylor expansion of tensor fields under the action of one-parameter families (not necessarily groups) of diffe

Gwoho Liu

We obtain a global resolution for the sheaf of differential operators on smooth geometric quotients of free linear actions of algebraic groups. The terms of our resolution involve symmetric and alternating powers of vector bundles easily constructed geometrically from the algebraic group and the vector space on which it acts.

Matteo Campellone, Jean-Philippe Bouchaud

We generalise Bray's self-consistent screening approximation to describe the critical dynamics of the $ϕ^4$ theory. In order to obtain the dynamical exponent $z$, we have to make an ansatz for the form of the scaling functions, which fortunately can be much constrained by general arguments. Numerical values of $z$ for $d=3$, and $n=1,...,10$ are obtained

A. Sacuto, N. Bontemps, P. Monod, R. Combescot

Pure electronic Raman spectra with no phonon structures superimposed to the electronic continuum, are reported for the first time, in optimally doped $HgBa_{2}CaCu_{2}O_{6+δ} $ single crystals $(T_{c }=126 $ K). Our low temperature spectra (15 K) for the $A_{1g}$, $B_{1g} $ and $B_{2g} $ symmetries exhibit striking differences with previous data in $Bi_{2}Sr

Zurab Berezhiani

The horizontal symmetry $U(3)_H$ can greatly help in solving the flavor problems in the supersymmetric grand unification. We consider the $SU(5)\times U(3)_H$ model and show that it leads to the remarkable relations between the fermion mass matrices and the soft SUSY breaking terms. Dangerous supersymmetric contributions to the flavor-changing phenomena are

A. P. Bassom, P. A. Clarkson, C. K. Law, J. B. McLeod

In this work we propose a new method for investigating connection problems for the class of nonlinear second-order differential equations known as the Painlev{é} equations. Such problems can be characterized by the question as to how the asymptotic behaviours of solutions are related as the independent variable is allowed to pass towards infinity along diffe

P. A. Clarkson, E. L. Mansfield, T. J. Priestley

In this paper we study symmetry reductions of a class of nonlinear third order partial differential equations $u_t -εu_{xxt} +2κu_x= u u_{xxx} +αu u_x +βu_x u_{xx}$ where $ε$, $κ$, $α$ and $β$ are arbitrary constants. Three special cases of equation (1) have appeared in the literature, up to some rescalings. In each case the equation has admitted unusual tra

S. Rauch-Wojciechowski, A. V. Tsiganov

We examine the problem of integrability of two-dimensional Hamiltonian systems by means of separation of variables. The systematic approach to construction of the special non-pure coordinate separation of variables for certain natural two-dimensional Hamiltonians is presented. The relations with SUSY quantum mechanics are discussed.

Michel Dubois-Violette

We present some results concerning the generalized homologies associated with nilpotent endomorphisms $d$ such that $d^N=0$ for some integer $N\geq 2$. We then introduce the notion of graded $q$-differential algebra and describe some examples. In particular we construct the $q$-analog of the simplicial differential on forms, the $q$-analog of the Hochschild

M. van Hecke, B. A. Malomed

We consider domain walls (DW's) between single-mode and bimodal states that occur in coupled nonlinear diffusion (NLD), real Ginzburg-Landau (RGL), and complex Ginzburg-Landau (CGL) equations with a spatially dependent coupling coefficient. Group-velocity terms are added to the NLD and RGL equations, which breaks the variational structure of these models

T. Alm, G. Chanfray, P. Schuck, G. Welke

The possibility of pion--pair formation in a hot pion gas, based on the bosonic gap equation, is pointed out and discussed in detail. The critical temperature for condensation of pion pairs (Evans--Rashid transition) is determined as a function of the pion density. As for fermions, this phase transition is signaled by the appearance of a pole in the two--par

P. Papazoglou, J. Schaffner, S. Schramm, D. Zschiesche

We investigate the properties of different modifications to the linear $σ$-model (including a dilaton field associated with broken scale invariance) at finite baryon density $ρ$ and nonzero temperature $T$. The explicit breaking of chiral symmetry and the way the vector meson mass is generated are significant for the appearance of a phase of nearly vanishing

A. Polls, M. Radici, S. Boffi, W. H. Dickhoff

The cross section for the removal of high-momentum protons from 16O is calculated for high missing energies. The admixture of high-momentum nucleons in the 16O ground state is obtained by calculating the single-hole spectral function directly in the finite nucleus with the inclusion of short-range and tensor correlations induced by a realistic meson-exchange

H. Toki, S. Hirenzaki, K. Takahashi

Recently, deeply bound pionic states were found experimentally in (d, $^3$He) reactions on $^{208}$Pb. They found an isolated peak structure in the bound region below the pion production threshold. We study theoretically these excitation functions in (d, $^3$He) reactions on $^{208}$Pb at T$_d$=600 MeV. We found very good agreement with the (d, $^3$He) excit

David Gabai, G. Robert Meyerhoff, Nathaniel Thurston

This paper introduces a rigorous computer-assisted procedure for analyzing hyperbolic 3-manifolds. This technique is used to complete the proof of several long-standing rigidity conjectures in 3-manifold theory as well as to provide a new lower bound for the volume of a closed orientable hyperbolic 3-manifold. We prove the following result: \it\noindent Let

Gabriel Lopes Cardoso, Gottfried Curio, Dieter Lust, Thomas Mohaupt

In this note we compare the moduli spaces of the heterotic string compactified on a two-torus and F-Theory compactified on an elliptic K3 surface for the case of an unbroken E8 x E8 gauge group. The explicit map relating the deformation parameters alpha and beta of the F-Theory K3 surface to the moduli T and U of the heterotic torus is found using the close

Fuad Saradzhev

We consider the generalized chiral $QED_2$ on $S^1$ with a $U(1)$ gauge field coupled with different charges to both chiral components of a fermionic field. Using the adiabatic approximation we calculate the Berry phase and the corresponding ${\rm U}(1)$ connection and curvature for the vacuum and many particle Fock states. We show that the nonvanishing vacu

F. C. Khanna, A. Yu. Umnikov

We discuss connection between spin-dependent SFs of nucleons and nuclei in the deep inelastic lepton scattering. The case of the deuteron is studied in detail in the Bethe-Salpeter formalism.

L. H. Orr, T. Stelzer, W. J. Stirling

Radiation of gluons gives rise to extra jets in top quark events that can lead to complications in event reconstruction and mass measurement. I review recent results for gluon radiation in top quark production and decay, and discuss their implications for top quark physics.

A. Yu. Umnikov, Han-xin He, F. C. Khanna

The chiral-odd structure function h_{1}^D(x) and the tensor charge of the deuteron are studied within the Bethe-Salpeter formalism for the deuteron amplitude. Utilizing a simple model for the nucleon structure function, h_1^N, h_1^D(x) is calculated and the nuclear effects are analyzed.

Marek Jezabek, Leszek Motyka

Perturbative corrections of the order of $α_s$ to inclusive double differential lepton distribution from $b$ quark decay are considered. A perturbative correction to the charged lepton energy spectrum has been calculated for an arbitrary charged lepton mass. The perturbative contribution suppresses the partial rate but almost does not change the shape of ene

E. Laenen, M. Buza, B. W. Harris, Y. Matiounine

Deep-inelastic production of heavy quarks at HERA, especially charm, is an excellent signal to measure the gluon distribution in the proton at small $x$ values. By measuring various differential distributions of the heavy quarks this reaction permits additional more incisive QCD analyses due to the many scales present. Furthermore, the relatively small mass

Jamal Jalilian-Marian

Gluon distribution function at small x is computed using the extended McLerran-Venugopalan model. A lipatov like enhancement is seen as well as a non-trivial transverse momentum dependence which is estimated. It is shown that gluon density saturates at small x which would lead to unitarization of cross sections computed with this distribution function.

Klaus Geiger

I discuss an approach to derive from first principles, a real-time formalism to study the dynamical interplay of quantum and statistical-kinetic properties of non-equilibrium multi-parton systems produced in high-energy QCD processes. The ultimate goal (from which one is still far away) is to have a practically applicable description of the space-time evolut

S. Pepin, Fl. Stancu, M. Genovese, J. -M. Richard

We discuss the stability of multiquark systems within the recent model of Glozman et al. where the chromomagnetic hyperfine interaction is replaced by pseudoscalar-meson exchange contributions. We find that such an interaction binds a heavy tetraquark systems $QQ\bar q\bar q$ ($Q=c,b and q=u,d)$ by 0.2-0.4 GeV. This is at variance with results of previous mo

G. Montagna, F. Piccinini, J. Layssac, F. M. Renard

We consider the effects of a number of models with one extra $Z$, with enhanced couplings to quarks, in the final \underline{hadronic} channels at LEP2. We show that, for a number of representative cases, visible effects could be produced even for very low values of the \underline{lepton} couplings, much smaller than the existing LEP1/SLC and the future LEP2

D. Delepine

In principle, the baryon asymmetry of the Universe can be generated at the electroweak phase transition but the experimental lower limit on the Higgs mass seems to rule out a Standard Model scenario. However, it has been shown recently that in the Minimal Supersymmetric Standard Model, the electroweak phase transition can be a strong enough first order one f

A. V. Sidorov

The simultaneous QCD analysis of the $xF_3$ structure functions measured in deep-inelastic scattering by several collaborations is done up to 3--loop order of QCD. The x dependence of the higher--twist contribution is evaluated and turns out to be in a qualitative agreement with the results of "old" CCFR data analysis and with renormalon approach pre

S. Dimopoulos, G. F. Giudice

We study gauge-mediated theories containing several messengers with the most general SU(5)-invariant mass and supersymmetry-breaking parameters. We show that these theories are predictive, containing only two relevant parameters more than the minimal gauge-mediated model. Hypercharge D-terms can contribute significantly to the right-handed charged sleptons a

S. M. Bilenky, C. Giunti, W. Grimus

Talk presented by S.M. Bilenky at the XVII International Conference on Neutrino Physics and Astrophysics, Helsinki, June 1996.

Stephen R. Sharpe

I describe recent developments in quenched chiral perturbation theory (QChPT) and the status of weak matrix elements involving light quarks. I illustrate how, with improved statistical errors, and with calculations of the masses of baryons containing non-degenerate quarks, there is now a clear need for extrapolations of higher order than linear in the quark

J. Gunter

The reaction pi- p -> pi0 pi0 n may be used to examine both scalar and tensor mesons. The f0(980) signature changes from destructive interference at small momentum transfer to an enhancement at large momentum transfer. The f2(1270) production mechanism also changes as a function of momentum transfer. Unnatural parity exchange dominates at small |t|, natural

V. Del Duca, E. Gallo, P. Marage

The general framework of diffractive deep inelastic scattering is introduced and reports given in the session on diffractive interactions at the International Workshop on Deep-Inelastic Scattering and Related Phenomena, Rome, April 1996, are presented.

S. Aid

We present a search for excited electrons, neutrinos and quarks using the H1 detector at the $ep$ collider HERA, based on data taken in 1994 with an integrated luminosity of 2.75 pb$^{-1}$. Radiative decays of excited quarks and neutrinos have been investigated as well as decays of excited electrons into all possible electroweak gauge bosons. No evidence for

Gabriel B. Nagy, Reinaldo J. Gleiser, Andres D. Dagotto

We present a new family of exact solutions of the Einstein equations, constructed through the Khan-Penrose procedure, that may be interpreted as representing the propagation of a pair of solitons, in the background of a plane-wave collision spacetime. The metric in the interaction region is obtained as a diagonal solitonic perturbation of Rindler's space

C. Alvarez, R. B. Mann

We consider the empirical validity of the equivalence principle for non-baryonic matter. Working in the context of the TH\epsilon\mu formalism, we evaluate the constraints experiments place on parameters associated with violation of the equivalence principle (EVPs) over as wide a sector of the standard model as possible. Specific examples include new paramet

I-Ching Yang, Ching-Tzung Yeh, Rue-Ron Hsu, Chin-Rong Lee

Employing energy-momentum pseudotensor of Einstein, we obtian the energy distribution of a dyonic dilaton black hole. The energy distribution of this black hole depends on mass $ M $, electric charge $ Q_{e} $, magnetic charge $ Q_{m} $ and asymptotic values of the dilaton $ ϕ_{0} $. We also mmake some comparisons between the results of Virbhadra et. al. and

Takashi Hamazaki, Hideo Kodama

The behavior of scalar perturbations on superhorizon scales during the reheating stage is investigated by replacing the rapidly oscillating inflaton field by a perfect fluid obtained by spacetime averaging and the WKB approximation. The influence of the energy transfer from the inflaton to radiation on the evolution of the Bardeen parameter is examined for r

Vladimir S. Mashkevich

This paper is a sequel of the series of papers [gr-qc/9409010, gr-qc/9505034, gr-qc/9603022], being an immediate continuation and development of the latter of them. In the Friedmann universe, the equation $Ω_0=2q_0$ holds ($Ω$ is density parameter, $q$ is deceleration parameter, and subscript 0 indicates present-day values), which gives rise to the problem o

Beatriz Abadie, Ruy Exel

A study of Hilbert $C^*$-bimodules over commutative $C^*$-algebras is carried out and used to establish a sufficient condition for two quantum Heisenberg manifolds to be isomorphic.

B. -Y. Ha, D. Thirumalai

A functional integral formalism is used to derive the extension of a stiff chain subject to an external force. The force versus extension curves are calculated using a meanfield approach in which the hard constraint $u^2(s)=1$ is replaced by a global constraint $ < u^2(s) > = 1$ where $ u(s)$ is the tangent vector describing the chain and $s$ is the arc leng

L. Vina, L. Munoz, E. Perez, J. Fernandez-Rossier

We have observed a large spin splitting between &#34;spin&#34; $+1$ and $-1$ heavy-hole excitons, having unbalanced populations, in undoped GaAs/AlAs quantum wells in the absence of any external magnetic field. Time-resolved photoluminescence spectroscopy, under excitation with circularly polarized light, reveals that, for high excitonic density and short ti

P. Calvani, A. Paolone, P. Dore, S. Lupi

We report on the infrared absorption spectra of three oxides where charged superlattices have been recently observed in diffraction experiments. In La$_{1.67}$Sr$_{0.33}$NiO$_4$, polaron localization is found to suppress the low-energy conductivity through the opening of a gap and to split the $E_{2u}$-$A_{2u}$ vibrational manifold of the oxygen octahedra. S

P. Czerner, U. Ritschel

We theoretically investigate the spatial dependence of the order parameter of the two-dimensional semi-infinite Ising model with a free surface at or above the bulk critical temperature. Special attention is paid to the influence of a surface magnetic field $h_1$ and the crossover between the fixed points at h_1=0 and h_1=infinity. The sharp increase of the

U. Ritschel, P. Czerner

We study relaxation processes in spin systems near criticality after a quench from a high-temperature initial state. Special attention is paid to the stage where universal behavior, with increasing order parameter emerges from an early non-universal period. We compare various algorithms, lattice types, and updating schemes and find in each case the same univ

Anatoley T. Zheleznyak, Victor M. Yakovenko, Igor E. Dzyaloshinskii

We study instabilities occurring in the electron system whose Fermi surface has flat regions on its opposite sides. Such a Fermi surface resembles Fermi surfaces of some high-$T_c$ superconductors. In the framework of the parquet approximation, we classify possible instabilities and derive renormalization-group equations that determine the evolution of corre

Sidney van den Bergh

Globular clusters with composite color-magnitude diagrams, such as NGC 1851, NGC 2808 and Fornax No. 3, might have formed by mergers. It is suggested that each of these objects had two parent clusters, one with a red horizontal branch and another with a blue horizontal branch. Such mergers could have occurred if both ancestral objects were originally members

Mark W. Sincell, Julian H. Krolik

Motivated by recent work indicating that the UV continuum in AGN may be produced by reradiation of energy absorbed from X-rays irradiating an accretion disk, we present a calculation of the vertical structures and ultraviolet spectra of X-ray irradiated accretion disks around massive non-rotating black holes. After finding the radial dependence of vertically

Kei Iida, Katsuhiko Sato

Transitions of nuclear compositions in the crust of a neutron star induced by stellar spin-down are evaluated at zero temperature. We construct a compressible liquid-drop model for the energy of nuclei immersed in a neutron gas, including pairing and shell correction terms, in reference to the known properties of the ground state of matter above neutron drip

E. Izadi

Let $V$ be a subvariety of codimension $\leq g$ of the moduli space $\cA_g$ of principally polarized abelian varieties of dimension $g$ or of the moduli space $\tM_g$ of curves of compact type of genus $g$. We prove that the set $E_1(V)$ of elements of $V$ which map onto an elliptic curve is analytically dense in $V$. From this we deduce that if $V \subset \

Jose Riera, Karen Hallberg, Elbio Dagotto

Ground state properties of the Kondo model for manganese oxides in one dimension are studied using numerical techniques. The large Hund coupling ($J_{H}$) limit is specially analyzed. A robust region of fully saturated ferromagnetism (FM) is identified at all densities. For open boundary conditions it is shown exactly that the ground state is FM at $J_{H} =

Serge Winitzki

A discretized massless wave equation in two dimensions, on an appropriately chosen square lattice, exactly reproduces the solutions of the corresponding continuous equations. We show that the reason for this exact solution property is the discrete analog of conformal invariance present in the model, and find more general field theories on a two-dimensional l

M. J. de la Plata, L. L. Salcedo

A derivation is given of the Feynman rules to be used in the perturbative computation of the Green&#39;s functions of a generic quantum many-body theory when the action which is being perturbed is not necessarily quadratic. Some applications are discussed.

Katsushi Ito, Naoki Sasakura

We study the low-energy effective theory in N=2 SU(Nc) supersymmetric QCD with Nf =< 2Nc fundamental hypermultiplets in the Coulomb branch by microscopic and exact approaches. We calculate the one-instanton correction to the modulus u=< 1/2 Tr A^2 > from microscopic instanton calculation. We also study the one-instanton corrections from the exact solutions f

John W. Barrett, Louis Crane

We make a direct connection between the construction of three dimensional topological state sums from tensor categories and three dimensional quantum gravity by noting that the discrete version of the Wheeler-DeWitt equation is exactly the pentagon for the associator of the tensor category, the Biedenharn-Elliott identity. A crucial role is played by an asym

J. Zimanyi, T. S. Biro, T. Csorgo, P. Levai

We introduce the Transchemistry Model as a dynamical extension of the Algebraic Coalescence Rehadronization (ALCOR) model in describing the hadronization of quark matter which is expected to be produced in relativistic heavy ion collisions. Results are presented for CERN SPS NA49 Pb+Pb experiment calculating hadron multiplicities and momentum spectra. The fr

A. Honecker, I. Peschel

We re-examine a two-dimensional forest-fire model via Monte-Carlo simulations and show the existence of two length scales with different critical exponents associated with clusters and with the usual two-point correlation function of trees. We check resp. improve previously obtained values for other critical exponents and perform a first investigation of the

A. Borowiec

A new notion of Cartan pairs as a substitute of notion of vector fields in noncommutative geometry is proposed. The correspondence between Cartan pairs and differential calculi is established.

Martin van Hecke, Wim van Saarloos

The coefficients of the complex Ginzburg-Landau equations that describe weakly nonlinear convection in a large rotating annulus are calculated for a range of Prandtl numbers $σ$. For fluids with $σ\approx 0.15$, we show that the rotation rate can tune the coefficients of the corresponding amplitude equations from regimes where coherent patterns prevail to re

A. Boudard, G. Faeldt, C. Wilkin

Using the simple relation between the np scattering and bound state wave functions, the spin-triplet contributions to the pp -> pi+ (pn) and backward dp -> p(pn) reactions are estimated for low np excitation energies. The good agreement with the pion production data at 400 and 450 MeV over a range of angles shows that spin-singlet final states cannot be more

J. Caro, E. Ruiz Arriola, L. L. Salcedo

The $σ$-$ω$ model of nuclei is studied at leading order in the $1/N$ expansion thereby introducing the self consistent Hartree approximation, the Dirac sea corrections and the one fermion loop meson self energies in a unified way. For simplicity, the Dirac sea is further treated within a semiclassical expansion to all orders. The well-known Landau pole vacuu

Chi Tat Chong, Sy D. Friedman

In this article, intended for the Handbook of Recursion Theory, we survey recursion theory on the ordinal numbers, with sections devoted to $α$-recursion theory, $β$-recursion theory and the study of the admissibility spectrum.

Sy D. Friedman

Assuming that ORD is $ω+ω$-Erdös we show that if a class forcing amenable to $L$ (an $L$-forcing) has a generic then it has one definable in a set-generic extension of $L[O^\#]$. In fact we may choose such a generic to be {\it periodic} in the sense that it preserve the indiscernibility of a final segment of a periodic subclass of the Silver indiscernibles,

R. J. Henderson, S. G. Rajeev

We obtain direct, finite, descriptions of a renormalized quantum mechanical system with no reference to ultraviolet cutoffs and running coupling constants, in both the Hamiltonian and path integral pictures. The path integral description requires a modification to the Wiener measure on continuous paths that describes an unusual diffusion process wherein coll

Pirjo Pasanen

The supersymmetric version of a topological quantum field theory describing flat connections, the super BF-theory, is studied in the superspace formalism. A set of observables related to topological invariants is derived from the curvature of the superspace. Analogously to the non-supersymmetric versions, the theory exhibits a vector-like supersymmetry. The

Igor Bandos, Alexey Maznytsia, Igor Rudychev, Dmitri Sorokin

We study some features of bosonic particle path-integral quantization in a twistor-like approach by use of the BRST-BFV quantization prescription. In the course of the Hamiltonian analysis we observe links between various formulations of the twistor-like particle by performing a conversion of the Hamiltonian constraints of one formulation to another. A parti

M. Ciafaloni, P. Valtancoli

We derive, in 2+1 dimensions, classical solutions for metric and motion of two or more spinning particles, in the conformal Coulomb gauge introduced previously. The solutions are exact in the $N$-body static case, and are perturbative in the particles&#39; velocities in the dynamic two-body case. A natural boundary for the existence of our gauge choice is pr

Ingemar Bengtsson, Astri Kleppe

Some aspects of chiral p-forms, in particular the obstruction that makes it hard to define covariant Green functions, are discussed. It is shown that a proposed resolution involving an infinite set of gauge fields can be made mathematically rigourous in the classical case. We also give a brief demonstration of species doubling for chiral bosons.

Martin Gremm, Iain Stewart

We compute the α_s^2β_0 part of the two-loop QCD corrections to the charged lepton spectrum in b \to c \ell \barν_\ell decays and find them to be about 50\% of the first order corrections at all lepton energies, except those close to the end point. Including these corrections we extract the central values \barΛ=0.33 GeV and λ_1=-0.17 GeV^2 for the HQET matri

S. Dawson

I summarize some of the highlights of the 1996 DPF meeting, paying particular attention to new measurements of the $W$, $Z$, and top quark masses. Precision electroweak measurements from LEP are discussed with emphasis on recent measurements of $R_b$ and values of the coupling constants $α(M_Z^2)$ and $α_s(M_Z^2)$ are presented. Taken as a whole, the data ar

T. Barnes, F. E. Close, P. R. Page, E. S. Swanson

We discriminate gluonic hadrons from conventional $q\bar q$ states by surveying radial and orbital excitations of all I=0 and I=1 $n\bar n$ systems anticipated up to 2.1 GeV. We give detailed predictions of their quasi-two-body branching fractions and identify characteristic decay modes that can isolate quarkonia. Several of the ``missing mesons&#39;&#39; wi

Eric Braaten

The NRQCD factorization approach for calculating inclusive production of heavy quarkonium gives unambiguous predictions for the polarization of quarkonium states. The factorization formula for polarized states can be obtained by using the threshold expansion method to calculate the short-distance coefficients and then using symmetries of NRQD to reduce the N

R. Eichler, S. Frixione

We discuss the impact of the planned upgrades of the HERA collider on the study of open heavy flavour and quarkonium production. New experimental techniques in charm physics are presented.

S. Frixione

I discuss few selected topics in heavy flavour photoproduction at HERA which require large integrated luminosity in order to be experimentally investigated. I present phenomenological predictions for bottom production. As a possible application of measurements involving double-tagged charm events, I outline a method for the direct measurement of the gluon de

G. Abbiendi, J. M. Butterworth, R. Graciani

The expected rates for charm-tagged jet photoproduction are evaluated for a number of tagging procedures, and some of the physics potential is discussed. Charm in jets is tagged using $D^*$&#39;s, $μ$&#39;s, or tracks from secondary vertices which might be identified in a microvertex detector. We find high expected event rates, leading to the possibility of

W. Kilian

In the absence of a Higgs particle vector boson scattering amplitudes are generally described by an electroweak chiral Lagrangian below the resonance region. For a Linear Collider with CMS energy $\sqrt{s}=1.6 TeV$ and an integrated luminosity of $200 fb^{-1}$ we estimate the sensitivity on the chiral parameters $α_4$ and $α_5$. We consider the processes $e^

E. Bagan, M. Lavelle, D. McMullan, B. Fiol

We motivate the use of dressed charges by arguing that such objects are needed to describe, e.g., constituent quarks and, in general, physical charged states in gauge theories. We give a short introduction to dressings in both QED and QCD. We put special emphasis on the infra-red properties of a moving dressed charge. To be more precise, we demonstrate that

Robert Fleischer

The $B_s$ system is analyzed in light of a possible width difference $ΔΓ_s$ between its mass eigenstates. If $ΔΓ_s$ is sizable, untagged $B_s$-meson decays may allow a probe of CP violation and moreover the extraction both of the Wolfenstein parameter $η$ and of the notoriously difficult to measure angle $γ$ of the unitarity triangle. To accomplish this ambi

Howard E. Haber, Ralf Hempfling, Andre H. Hoang

To obtain the most accurate predictions for the Higgs masses in the minimal supersymmetric model (MSSM), one should compute the full set of one-loop radiative corrections, resum the large logarithms to all orders, and add the dominant two-loop effects. A complete computation following this procedure yields a complex set of formulae which must be analyzed num

E. Bagan, M. Lavelle, D. McMullan, B. Fiol

Systematic approaches to building up gauge invariant descriptions of charged fields, such as electrons or quarks, are described. Physically relevant descriptions must then be singled out from a multiplicity of possibilities and to this end we give a physical interpretation of one description. Perturbative calculations which back up this interpretation are ou

J. Soffer, O. V. Teryaev

We perform the isospin decomposition of proton and neutron SLAC data for moderately low $x$ in the region $0.01 \leq x \leq 0.1$. The isovector part is well described by a power behaviour $x^α$, where $α$ does not correspond to the intercept of single $a_1$ Regge trajectory, as expected. However, the observed power leads to the validity of Bjorken sum rule a

T-chi-L-Collaboration, :, L. Conti, N. Eicker

The investigation of light sea-quark effects in lattice QCD with dynamical Wilson fermions requires both larger physical volumes and finer lattice resolutions than achieved previously. As high-end supercomputers like the 512-node APE Tower provide the compute power to perform a major step towards the chiral limit (T-chi-L), we have launched a feasibility stu

M. Billo&#39;, M. Caselle, A. D&#39;Adda, S. Panzeri

We consider a lattice gauge theory at finite temperature in ($d$+1) dimensions with the Wilson action and different couplings $β_t$ and $β_s$ for timelike and spacelike plaquettes. By using the character expansion and Schwinger-Dyson type equations we construct, order by order in $β_s$, an effective action for the Polyakov loops which is exact to all orders

Ferdinando Gliozzi, Stefano Vinti

The interior of the color flux tube joining a quark pair can be probed by evaluating the correlator of pair of Polyakov loops in a vacuum modified by another Polyakov pair, in order to check the dual superconductivity conjecture which predicts a deconfined, hot core. We also point out that at the critical point of any 3D gauge theories with a continuous deco

Christoph Grab

A status report on the prospects of measuring rare decays of charmed mesons at HERA is given. Based on actual experience with measuring charm at HERA, the sensitivity on limits of rare decays is estimated.

Sunme Kim, Freydoon Mansouri

We show that the exact solution of the two_superbody problem in N=2 Chern Simons Supergravity in 2+1 dimensions leads to a supermultiplet of space-times. This supersymmetric space-time is characterized by the two gauge invariant observables of the super Poincare&#39; group, which may be viewed as the Casimir invariants of an equivalent one-superbody state. T

Lee Smolin

It is argued that some approaches to non-perturbative quantum general relativity lack a sensible continuum limit that reproduces general relativity. The basic problem is that generic physical states lack long ranged correlations, because the form of the state allows a division into spatial regions, such that no change in the physical state in one region can

S. Mignemi

We study spherically symmetric solutions of a four-dimensional theory of gravity with a topological action, which was constructed as a Yang-Mills theory of the Poincaré group and can be considered a generalization to higher dimensions of well-known two-dimensional models. We also discuss the perturbative degrees of freedom and the properties of the theory un

Luca Amendola, Carlo Baccigalupi, Franco Occhionero

It is already understood that the increasing observational evidence for an open Universe can be reconciled with inflation if our horizon is contained inside one single huge bubble nucleated during the inflationary phase transition. In this frame of ideas, we show here that the probability of living in a bubble with the right $Ω_0$ (now the observations requi

Lee Smolin

A string theory in $3$ euclidean spacetime dimensions is found to describe the semiclassical behavior of a certain exact physical state of quantum general relativity in $4$ dimensions. Both the worldsheet and the three dimensional metric emerge as collective coordinates that describe a sector of the solution space of quantum general relativity. Additional co

Yasusada Nambu, Atsushi Taruya

The evolution of the cosmological perturbation during the oscillatory stage of the scalar field is investigated. For the power law potential of the inflaton field, the evolution equation of the Mukhanov&#39;s gauge invariant variable is reduced to the Mathieu equation and the density perturbation grows by the parametric resonance.

David R. Reichman, Peter Neu, Robert J. Silbey

We discuss the recent theory of Burin and Kagan that attempts to explain the existence of universal low temperature properties in amorphous solids. We suggest a realistic experimental scenario that could be used to test the theory. We comment on the results of an experiment that has already been performed in the proposed geometry.