June 1995 arXiv papers — page 2

S. Grabowski, J. Schmalian, M. Langer, K. H. Bennemann

The doping dependence of the superconducting state for the 2D one-band Hubbard Hamiltonian is determined. By using an Eliashberg-type theory, we find that the gap function $Δ_{\bf k}$ has a $d_{x^2-y^2}$ symmetry in momentum space and T$_c$ becomes maximal for $13 \; \%$ doping. Since we determine the dynamical excitations directly from real frequency axis c

F. Seno, J. M. Yeomans

We develop an analytic approach which allows us to study the behaviour of spin models with competing interactions and $p$-fold spin anisotropy, $D$, in the limit where the pinning potential which results from $D$ is large. This is an expansion in inverse spin anisotropy which must be carried out to all orders where necessary. Interesting behaviour occurs nea

Seungoh Ryu, Wenbin Yu, D. Stroud

We show analytically that the dynamical equations for an underdamped ladder of coupled small Josephson junctions can be approximately reduced to the discrete sine-Gordon equation. As numerical confirmation, we solve the coupled Josephson equations for such a ladder in a magnetic field. We obtain discrete-sine-Gordon-like IV characteristics, including a flux

Cem Bozsahin, Elvan Gocmen

This paper describes a computational framework for a grammar architecture in which different linguistic domains such as morphology, syntax, and semantics are treated not as separate components but compositional domains. Word and phrase formation are modeled as uniform processes contributing to the derivation of the semantic form. The morpheme, as well as the

Corey S. O'Hern, David A. Egolf, Henry S. Greenside

By simulating a nonequilibrium coupled map lattice that undergoes an Ising-like phase transition, we show that the Lyapunov spectrum and related dynamical quantities such as the dimension correlation length~$ξ_δ$ are insensitive to the onset of long-range ferromagnetic order. As a function of lattice coupling constant~$g$ and for certain lattice maps, the Ly

Luigi Spinoglio, Matthew A. Malkan, Brian Rush, Luis Carrasco

Aperture photometry from our own observations and the literature is presented for the 12\um\ Galaxies in the near infrared J, H and K bands and, in some cases, in the L band. These data are corrected to ``total'' near--infrared magnitudes, (with a typical uncertainty of 0.3 magnitudes) for a direct comparison with our IRAS fluxes which apply to the e

Heino Falcke, Peter L. Biermann

In order to further test our hypothesis that jets and disk around compact accreting objects are symbiotic features we investigate the newly discovered superluminal galactic radio jets GRS 1915+105 and GRO J1655-40 and the two famous galactic radio jets 1E1740-2942 and SS 433 within the framework of our couple jet/disk model developed initially for active gal

A. Libgober

A formula for calculating the Lefschetz number of an automorphism acting on a crepant resolution for a quotient of a Kahler manifold derived from an equivariant version of McKay correspondence. The latter is proven in some cases. As an application the Lefschetz numbers of of involutions acting on Calabi-Yau threefolds and their mirrors are compared.

Fabian H. L. Essler, Vladimir Rittenberg

We consider the one-dimensional partially asymmetric exclusion model with open boundaries. The model describes a system of hard-core particles that hop stochastically in both directions with different rates. At both boundaries particles are injected and extracted. By means of the method of Derrida, Evans, Hakim and Pasquier the stationary probability measure

R. Sekhar Chivukula, Bogdan Dobrescu, John Terning

In this talk we review the physics of top-quark mass generation in models of dynamical electroweak symmetry breaking and the constraints on this physics arising from limits on the deviation of the weak interaction $ρ$-parameter from one. We then discuss top-color assisted technicolor in this context.

Kirsten Büttner, M. R. Pennington

We illustrate that solution of the Schwinger-Dyson equation for the gluon propagator in QCD does not support an infrared softened behaviour, but only an infrared enhancement. This has consequences for the modelling of the Pomeron in terms of dressed gluon exchange. It highlights that an understanding of the Pomeron within QCD must take account of the bound s

John W. Barrett

The physics of quantum gravity is discussed within the framework of topological quantum field theory. Some of the principles are illustrated with examples taken from theories in which space-time is three dimensional.

Nobuyuki Sakai, Hisa-aki Shinkai, Takashi Tachizawa, Kei-ichi Maeda

We study the dynamics of topological defects in the context of ``topological inflation" proposed by Vilenkin and Linde independently. Analysing the time evolution of planar domain walls and of global monopoles, we find that the defects undergo inflationary expansion if $η\stackrel{>}{\sim}0.33m_{Pl}$, where $η$ is the vacuum expectation value of the Higg

A. C. Davis, K. Dimopoulos

We show that, during false vacuum inflation, a primordial magnetic field can be created, sufficiently strong to seed the galactic dynamo and generate the observed galactic magnetic fields. Considering the inflaton dominated regime, our field is produced by the Higgs-field gradients, resulting from a grand unified phase transition. The evolution of the field

P. Bantay, P. Vecsernyes

Unitary representations of centrally extended mapping class groups $\tilde M_{g,1}, g\geq 1$ are given in terms of a rational Hopf algebra $H$, and a related generalization of the Verlinde formula is presented. Formulae expressing the traces of mapping class group elements in terms of the fusion rules, quantum dimensions and statistics phases are proposed.

Kikuo Harigaya

We study the antiferromagnetic phase of the C60-polymer doped with one electron per one C60 by using a tight-binding model with long-range Coulomb interactions. The model is solved by the unrestricted Hartree-Fock approximation, and a phase diagram is obtained by changing Coulomb interaction strengths and a conjugation parameter between C60 molecules. We fin

Christine Thielen

This paper presents an incremental method for the tagging of proper names in German newspaper texts. The tagging is performed by the analysis of the syntactic and textual contexts of proper names together with a morphological analysis. The proper names selected by this process supply new contexts which can be used for finding new proper names, and so on. Thi

G. K. Savvidy, K. G. Savvidy

We have found that the Regge gravity \cite{regge,sorkin}, can be represented as a $superposition$ of less complicated theory of random surfaces with $Euler~character$ as an action. This extends to Regge gravity our previous result \cite{savvidy}, which allows to represent the gonihedric string \cite{savvidy1} as a superposition of less complicated theory of

Han-Yong Choi

We study the thermodynamic properties of impure superconductors by explicitly taking into consideration the finiteness of electronic bandwidths within the phonon-mediated Eliashberg formalism. For a finite electronic bandwidth, the superconducting transition temperature, $T_c$, is suppressed by nonmagnetic impurity scatterings. This is a consequence of a red

Reginald T. Cahill, Susan M. Gunner

We report robust calculations of various low energy QCD hadronic properties. We use a multi-rank separable expansion for the gluon propagator which greatly facilitates the numerical computations within the Global Colour Model for QCD. The parameters for the propagators are determined by fitting experimental values for $f_π$ and the $π$ and $a_1$ meson masses

Laszlo E. Szabo

According to the widely accepted opinion, classical (statistical) physics does not support objective indeterminism, since the statistical laws of classical physics allow a deterministic hidden background, while --- as Arthur Fine writes polemizing with Grünbaum --- "{\sl the antilibertarian position finds little room to breathe in a statistical world if

J. M. G. Gomez, V. R. Manfredi, L. Salasnich

The spectral statistics of low--lying states of $fp$ shell nuclei are studied by performing large shell--model calculations with a realistic nuclear interaction. For $Ca$ isotopes, we find deviations from the predictions of the random--matrix theory which suggest that some spherical nuclei are not as chaotic in nature as the conventional view assumes.

S. V. Akulinichev

It is shown that nucleonic structure functions are $x-$ and $Q^{2}-$rescaled in nuclei. The $x-$rescaling accounts for nuclear effects in the case of exact scaling, while the $Q^{2}-$rescaling is responsible for a corresponding modification of quantum corrections. This result is obtained in the leading order for all flavour combinations and connects the two

H. W. L. Naus, R. M. Davidson

The derivation of the `classical' low-energy theorem (LET) for γp \rightarrow pπ^0 is re-examined and compared to chiral perturbation theory. Both results are correct and are not contradictory; they differ because different expansions of the same quantity are involved. Possible modifications of the extended partially conserved axial-vector current relati

Kim Maltman

Two model-independent results on the momentum-dependence of $ρ$-$ω$ mixing are described. First, an explicit choice of interpolating fields for the vector mesons is displayed for which both the mixing in the propagator and the isospin-breaking at the nucleon-vector meson vertices (and hence also the one-vector-meson-exchange contribution to NN charge symmetr

A. Polyakov

We develop exact field theoretic methods to treat turbulence when the effect of pressure is negligible. We find explicit forms of certain probability distributions, demonstrate that the breakdown of Galilean invariance is responsible for intermittency and establish the operator product expansion. We also indicate how the effects of pressure can be turned on

C. Arvanitis, F. Geniet, A. Neveu

In this first paper we begin the application of variational methods to renormalisable asymptotically free field theories, using the Gross-Neveu model as a laboratory. This variational method has been shown to lead to a numerically convergent sequence of approximations for the anharmonic oscillator. Here we perform a sample calculation in lowest orders, which

Maximo Banados, Luis J. Garay, Marc Henneaux

The canonical structure of higher dimensional pure Chern-Simons theories is analysed. It is shown that these theories have generically a non-vanishing number of local degrees of freedom, even though they are obtained by means of a topological construction. This number of local degrees of freedom is computed as a function of the spacetime dimension and the di

Luca Lusanna

Relevant physical models are described by singular Lagrangians, so that their Hamiltonian description is based on the Dirac theory of constraints. The qualitative aspects of this theory are now understood, in particular the role of the Shanmugadhasan canonical transformation in the determination of a canonical basis of Dirac's observables allowing the el

J. Madore

Linear connections are introduced on a series of noncommutative geometries which have commutative limits. Quasicommutative corrections are calculated.

H. Neufeld, H. Rupertsberger

We investigate electromagnetic effects in the framework of chiral perturbation theory. Using a completely independent method, we confirm Urech's results for the divergences of the one--loop functional in the electromagnetic sector. We perform a one--loop analysis of all $P_{\ell 2}$ ($P = π, K, η$) and the $K_{\ell 3}$ form factors $f_+^{K^+π^0}(0)$, $f_

W. Buchmuller, A. Hebecker

It is demonstrated that the global properties of the rapidity gap events at HERA can be understood based on electron-gluon scattering and a non-perturbative mechanism of colour neutralization. Using the measured inclusive structure function $F_2$ to determine the parameters of the parton model, the diffractive structure function $F_2^D$ is predicted. The rat

J. Blümlein

The $k_{\perp}$ dependent gluon distribution for protons, pions,and photons is calculated accounting for the resummation of small~$x$ effects due to the Lipatov equation. It is represented by a convolution of a gluon density in the collinear limit and a universal function ${\cal G}(x,k^2,μ)$ for which an analytic expression is derived.

F. Farchioni, P. Hasenfratz, F. Niedermayer, A. Papa

In order to support the formal renormalization group arguments that the fixed point action of an asymptotically free model gives cut--off independent physical predictions in 1--loop perturbation theory, we calculate the finite volume mass--gap $m(L)$ in the non--linear $σ$--model. No cut--off effect of the type $g^4\left(a/L\right)^n$ is seen for any $n$. Th

A. Abrahams, A. Anderson, Y. Choquet-Bruhat, J. W. York,

The evolution of physical and gauge degrees of freedom in the Einstein and Yang-Mills theories are separated in a gauge-invariant manner. We show that the equations of motion of these theories can always be written in flux-conservative first-order symmetric hyperbolic form. This dynamical form is ideal for global analysis, analytic approximation methods such

Y. Choquet-Bruhat, J. W. York,

We show that, given an arbitrary shift, the lapse $N$ can be chosen so that the extrinsic curvature $K$ of the space slices with metric $\overline g$ in arbitrary coordinates of a solution of Einstein's equations satisfies a quasi-linear wave equation. We give a geometric first order symmetric hyperbolic system verified in vacuum by $\overline g$, $K$ an

Hans-Juergen Matschull

General aspects of vielbein representation, ADM formulation and canonical quantization of gravity are reviewed using pure gravity in three dimensions as a toy model. The classical part focusses on the role of observers in general relativity, which will later be identified with quantum observers. A precise definition of gauge symmetries and a classification o

Patrick R. Brady, John D. Smith

The singularity structure of charged spherical collapse is studied by considering the evolution of the gravity-scalar field system. A detailed examination of the geometry at late times strongly suggests the validity of the mass-inflation scenario~\cite{PI:90}. Although the area of the two-spheres remains finite at the Cauchy horizon, its generators are event

Giampiero Esposito, Alexander Yu. Kamenshchik, Igor V. Mishakov, Giuseppe Pollifrone

The discrepancy between the results of covariant and non-covariant one-loop calculations for higher-spin fields in quantum cosmology is analyzed. A detailed mode-by-mode study of perturbative quantum gravity about a flat Euclidean background bounded by two concentric 3-spheres, including non-physical degrees of freedom and ghost modes, leads to one-loop ampl

Giampiero Esposito

The contribution of physical degrees of freedom to the one-loop amplitudes of Euclidean supergravity is here evaluated in the case of flat Euclidean backgrounds bounded by a three-sphere, recently considered in perturbative quantum cosmology. The physical degrees of freedom (denoted by PDF) are picked out by imposing the supersymmetry constraints and choosin

Sung-Won Kim, Won T. Kim

A two-dimensional dilatonic black hole induced by a topological soliton is exactly solvable in the scalar field theory coupled to dilaton gravity. The Hawking radiation of the black hole is studied in the one-loop approximation with the help of the trace anomaly of energy-momentum tensors which is a geometrical invariant. The quantum theory can be also solub

Huaxin Lin, N. Christopher Phillips

We prove that if two nonzero homomorphisms from the Cuntz algebra O_infinity to a purely infinite simple C*-algebra have the same class in KK-theory, and if either both are unital or both are nonunital, then they are approximately unitarily equivalent. It follows that O_infinity is classifiable in the sense of Rordam. In particular, Rordam's classificati

Gerard J. Murphy, N. Christopher Phillips

We say that a unital C*-algrebra A has the approximate positive factorization property (APFP) if every element of A is a norm limit of products of positive elements of A. (There is also a definition for the nonunital case.) T. Quinn has recently shown that a unital AF algebra has the APFP if and only if it has no finite dimensional quotients. This paper is a

A. Schmeller, J. P. Eisenstein, L. N. Pfeiffer, K. W. West

We have employed tilted-field magneto-transport measurements of the energy gap for the odd-integer quantized Hall states at Landau level filling factors $ν= 1$,3 and 5 to determine the spin of thermally excited quasielectron-quasihole pairs. At $ν= 1$ our data show that as many as 7 electron spin flips accompany such excitations, while at $ν=3$ and 5 apparen

Peter Kopietz

The single-particle Green's function of an interacting Fermi system with dominant forward scattering is calculated by decoupling the interaction by means of a Hubbard-Stratonowich transformation involving a bosonic auxiliary field $ϕ^α$. We obtain a higher dimensional generalization of the well-known one-dimensional bosonization result for the Green'

Kurt Broderix, Reiner Kree

We give a corrected version of the algorithm presented within the commented paper by M.A. Novotny, Phys. Rev. Lett. Vol. 74, 1 (1995) (cond-mat/9411086)

J. M. Yeomans

Models with competing interactions, for example the ANNNI model, can have special points at which the ground state is infinitely degenerate, so-called multiphase points. Small perturbations can lift this degeneracy and give rise to infinite sequences of long-period phases. This paper compares the effect of three possible perturbations, quantum fluctuations,

W. A. Atkinson, J. P. Carbotte

We calculate the penetration depth $λ$ in the $a$, $b$ and $c$ directions for a simple model of YBa$_2$Cu$_3$O$_7$. In this model there are two layers---representing a CuO$_2$ plane and a CuO chain---per unit cell. There is a BCS--like pairing (both $s$ wave and $d$ wave are considered) interaction localised in the CuO$_2$ planes. The CuO chains become super

T. Nakajima, H. Aoki

Effect of interlayer tunneling in the double-layer fractional quantum Hall system at the total Landau level filling of $ν=1/m$ ($m$: odd integer) is analyzed with the composite-fermion approach in which the flux attachment is directly applied to the electron-electron interaction. A comparison with a numerical result indicates that the vertically coupled Laug

R. Schack, C. M. Caves

Hypersensitivity to perturbation is a criterion for chaos based on the question of how much information about a perturbing environment is needed to keep the entropy of a Hamiltonian system from increasing. We demonstrate numerically that hypersensitivity to perturbation is present in the following quantum maps: the quantum kicked top, the quantum baker's

B. A. McLeod, M. J. Rieke

We present models predicting the magnitude, redshift, and color distributions of field galaxies. We explore whether a fading starburst scenario can account for the observations of faint blue galaxies. We marginally rule out a starburst scenario with a local IMF because the models predict too many nearby faint galaxies that are not observed. A burst model wit

Amir Levinson, Roger Blandford

Recent observations of GRS 1915+105 and GRO J1655+40 reveal superluminal motions in Galactic sources. This letter examines the physical conditions within these Galactic sources, their interaction with their environment, their possible formation, and contrasts them with their extragalactic counterparts. In particular, e$^{+}$-e$^{-}$ and e-p jets are contrast

Michael D. Gregg

Using single channel infrared photometry from the literature, a provisional K-band diameter--velocity dispersion relation for elliptical galaxies in the Coma and Virgo clusters is derived. The Coma cluster relation has \~1.5 times lower scatter at K than in B or V. Excluding 4 outliers, the RMS scatter at K for 24 galaxies in Coma is only 4.8% in distance, c

Alice K. Harding

Compact steady sources of X-ray emission have been detected at the positions of at least two soft gamma-ray repeaters (SGRs). These sources have been interpreted as synchrotron nebulae powered by the neutron star that is causing the bursts. We explore a plerion model for the sources surrounding SGRs where the steady observed emission is powered by the SGR bu

Y. P. Jing, G. Boerner, R. Valdarnini

In this paper, we use large $\pppm$ N-body simulations to study the three-point correlation function $ζ$ of clusters in two theoretical models. The first model (LCDM) is a low-density flat model of $Ω_0=0.3$, $Λ_0=0.7$ and $h=0.75$, and the second model (PIM) is an Einstein-de-Sitter model with its linear power spectrum obtained from observations. We found t

D. Ruffolo, T. Khumlumlert

We have performed numerical simulations of the interplanetary transport of solar cosmic rays. The particles form a coherent pulse within $\sim0.01$ AU after their injection. The gradual decrease of a pulse's speed and anisotropy can be understood in terms of an equilibrium between pitch-angle scattering and focusing. The results should be useful for esti

D. Kabat, S. H. Shenker, M. J. Strassler

We consider corrections to the entropy of a black hole from an $O(N)$ invariant linear $\s$-model. We obtain the entropy from a $1/N$ expansion of the partition function on a cone. The entropy arises from diagrams which are analogous to those introduced by Susskind and Uglum to explain black hole entropy in string theory. The interpretation of the \sm entrop

M. Matone

The critical curve ${\cal C}$ on which ${\rm Im}\,\hatτ=0$, $\hatτ=a_D/a$, determines hyperbolic domains whose Poincaré metric is constructed in terms of $a_D$ and $a$. We describe ${\cal C}$ in a parametric form related to a Schwarzian equation and prove new relations for $N=2$ Super $SU(2)$ Yang-Mills. In particular, using the Koebe 1/4-theorem and Schwarz

Keith A. Olive, Sean T. Scully

WThe current status of big bang nucleosynthesis is reviewed with an emphasis on the comparison between the observational determination of the light element abundances of \D, \he3, \he4 and \li7 and the predictions from theory. In particular, we present new analyses for \he4 and \li7. Implications for physics beyond the standard model are also discussed. Limi

Ph. Jacquod, D. L. Shepelyansky

We study statistical properties of a class of band random matrices which naturally appears in systems of interacting particles. The local spectral density is shown to follow the Breit-Wigner distribution in both localized and delocalized regimes with width independent on the band/system size. We analyse the implications of this distribution to the inverse pa

T. Watabe, Chr. V. Christov, K. Goeke

We calculate the axial form factor in the chiral quark soliton (semibosonized Nambu - Jona-Lasinio) model using the semiclassical quantization scheme in the next to leading order in angular velocity. The obtained axial form factor is in a good absolute (without additional scaling) agreement with the experimental data. Both the value at the origin and the $q$

R. Schack, T. A. Brun, I. C. Percival

Numerical simulation of individual open quantum systems has proven advantages over density operator computations. Quantum state diffusion with a moving basis (MQSD) provides a practical numerical simulation method which takes full advantage of the localization of quantum states into wave packets occupying small regions of classical phase space. Following and

P. Rehberg, S. P. Klevansky, J. H"ufner

The hadronization process for quarks combining into two mesons, q\bar q\to MM' at temperature T is described within the SU(3) Nambu- Jona-Lasinio model with finite current quark masses. Invariant matrix elements, cross-sections and transition rates are calculated to leading order in a 1/N_c expansion. Four independent classes, u\bar d, u\bar s, u\bar u a

Matej Pavsic

The relativistic theory of unconstrained $p$-dimensional membranes ($p$-branes) is further developed and then applied to the embedding model of induced gravity. Space-time is considered as a 4-dimensional unconstrained membrane evolving in an $N$-dimensional embedding space. The parameter of evolution or the evolution time $τ$ is a distinct concept from the

K. Behrend, Yu. Manin

We correct some errors in the earlier version of this paper. Most importantly, the definition of isogeny of marked stable graphs has changed.

J. Gonzalez, J. V. Alvarez

We propose a computational scheme for the Hubbard model in the C60 cluster in which the interaction with the Fermi sea of charges added to the neutral molecule is switched on sequentially. This is applied to the calculation of the balance of charging energies, within a low-energy truncation of the space of states which produces moderate errors for an interme

J. L. Petersen, J. Rasmussen, M. Yu

Since the work of Bershadsky and Ooguri and Feigin and Frenkel it is well known that correlators of $SL(2)$ current algebra for admissible representations should reduce to correlators for conformal minimal models. A precise proposal for this relation has been given at the level of correlators: When $SL(2)$ primary fields are expressed as $ϕ_j(z_n,x_n)$ with

V. D. Lyakhovsky

Quantum duality principle is applied to study classical limits of quantum algebras and groups. For a certain type of Hopf algebras the explicit procedure to construct both classical limits is presented. The canonical forms of quantized Lie-bialgebras are proved to be two-parametric varieties with two classical limits called dual. When considered from the poi

M. Chemtob

The string one loop renormalization of the gauge coupling constants is examined in abelian orbifold models. The contributions to string threshold corrections independent of the compactification moduli fields are evaluated numerically for several representative examples of orbifold models. We consider cases with standard and non-standard embeddings as well as

Mark D. Gould, Katrina E. Hibberd, Jon R. Links, Yao-Zhong Zhang

We give the quantum analogue of a recently introduced electron model which generalizes the Hubbard model with additional correlated hopping terms and electron pair hopping. The model contains two independent parameters and is invariant with respect to the quantum superalgebra $U_q(gl(2|1))$. It is integrable in one dimension by means of the quantum inverse s

Mark D. Gould, Jon R. Links, Yao-Zhong Zhang

A new general eigenvalue formula for the eigenvalues of Casimir invariants, for the type-I quantum superalgebras, is applied to the construction of link polynomials associated with {\em any} finite dimensional unitary irrep for these algebras. This affords a systematic construction of new two-variable link polynomials asociated with any finite dimensional ir

Ahmed Hindawi, Burt A. Ovrut, Daniel Waldram

A discussion of the number of degrees of freedom, and their dynamical properties, in higher-derivative gravitational theories is presented. The complete non-linear sigma model for these degrees of freedom is exhibited using the method of auxiliary fields. As a by-product we present a consistent non-linear coupling of a spin-2 tensor to gravitation. It is sho

M. Varagnolo, E. Vasserot

The goal of the present paper is to prove with simple algebraic methods a Schur duality between Cherednik's double affine Hecke algebra of type GL(l) and the toroidal quantum group of type SL(n+1) introduced by V. Ginzburg, M. Kapranov and E. Vasserot in their "Langlands duality on algebraic surfaces".

Ilya Kapovich

We obtain a criterion for quasiconvexity of a subgroup of an amalgamated free product of two word hyperbolic groups along a virtually cyclic subgroup. The result provides a method of constructing new word hyperbolic group in class (Q), that is such that all their finitely generated subgroups are quasiconvex. It is known that free groups, hyperbolic surface g

Ilya Kapovich

The main result of this paper states that for any group $G$ with an automatic structure $L$ with unique representatives one can construct a uniform partial algorithm which detects $L$-rational subgroups and gives their preimages in $L$. This provides a practical, not just theoretical, procedure for solving the occurrence problem for such subgroups.

Stefano De Leo, Pietro Rotelli

We show that, in quaternion quantum mechanics with a complex geometry, the minimal four Higgs of the unbroken electroweak theory naturally determine the quaternion invariance group which corresponds to the Glashow group. Consequently, we are able to identify the physical significance of the anomalous Higgs scalar solutions. We introduce and discuss the compl

Jose A. de Azcarraga, Alan J. Macfarlane

Fractional supersymmetry denotes a generalisation of supersymmetry which may be constructed using a single real generalised Grassmann variable, $θ= \barθ, \, θ^n = 0$, for arbitrary integer $n = 2, 3, ...$. An explicit formula is given in the case of general $n$ for the transformations that leave the theory invariant, and it is shown that these transformatio

M. Yoshimura

We develop a formalism to investigate the behavior of quantum field and quantum ground state when the field is coupled to perturbation that periodically oscillates. Working in the Schroedinger picture of quantum field theory, we confirm that the phenomenon of parametric resonance in the classical theory implies an instability of quantum vacuum, and correspon

Vladimir A. Kazakov, Matthias Staudacher, Thomas Wynter

We continue our study of matrix models of dually weighted graphs. Among the attractive features of these models is the possibility to interpolate between ensembles of regular and random two-dimensional lattices, relevant for the study of the crossover from two-dimensional flat space to two-dimensional quantum gravity. We further develop the formalism of larg

Tatsu Takeuchi

I will discuss the current status of the determination of $α(m_Z)$ and $α_s(m_Z)$.

Ira Z. Rothstein

In this talk I review the present bounds on the tau neutrino, concentrating on the possibility of bringing the mass bound below an MeV.

W. T. Giele, E. W. N. Glover, J. Yu

Hadron colliders offer a unique opportunity to test perturbative QCD because, rather than producing events at a specific beam energy, the dynamics of the hard scattering is probed simultaneously at a wide range of momentum transfers. This makes the determination of $\al$ and the parton density functions (PDF) at hadron colliders particularly interesting. In

W. T. Giele, E. W. N. Glover

We discuss the possibilities for extracting information on the parton density functions and the strong coupling constant from one- and two-jet events at the Fermilab TEVATRON. First we study the inclusive two-jet triply differential cross section $d^3σ/dE_Tdη_1dη_2$. Different $η_1$ and $η_2$ pseudorapidity regions are directly related to the parton momentum

William A. Ponce, Arnulfo Zepeda, Jesús M. Mira

We analyze U(1)$_H$ as a horizontal symmetry and its possibilities to explain the known elementary-fermion masses. We find that only two candidates, in the context of SU(3)$_c\otimes$SU(2)$_L\otimes$U(1)$_Y\otimes$U(1)$_H$ nonsupersymmetric, are able to fit the experimental result m$_b<<$m$_t$.

J. -P. Blaizot, E. Iancu

When computed to one-loop order in resummed perturbation theory, the non-abelian Debye mass appears to be logarithmically sensitive to the magnetic scale $g^2T$. More generally, we show that in higher orders power-like infrared divergences forbid the use of perturbation theory to calculate the corrections to Debye screening. A similar infrared problem occurs

J. Binnewies, B. A. Kniehl, G. Kramer

We present new sets of fragmentation functions for neutral kaons, both at leading and next-to-leading order. They are fitted to data on inclusive K^0 production in e^+e^- annihilation taken by MARK II at PEP (\sqrt s = 29 GeV) and by ALEPH at LEP. Our fragmentation functions lead to a good description of other e^+e^- data on inclusive K^0 production at vario

D. B. Lichtenberg

Quantitative corrections are estimated to three of Franklin&#39;s sum rules involving the masses of baryons containing at least one charmed quark and to three analogous sum rules for baryons containing at least one bottom quark. The corrections arise from three-body contributions to baryon interaction energies and are calculated from a semiempirical formula

Aleksander V. Sidorov, Dimiter B. Stamenov

The results of LO {\it Fixed point} QCD (FP-QCD) analysis of the CCFR data for the nucleon structure function $~xF_3(x,Q^2)~$ are presented. The predictions of FP-QCD, in which $~α_{s}(Q^2)~$ tends to a nonzero coupling constant $α_{0}$ as $~Q^2\to \infty~,$ are in good agreement with the data. If $~α_{0}~$ is a first order zero of the $~β~$ function, constr

Anne-Christine Davis, Patrick Peter

A synthesis of previous work done on the microscopic structure of cosmic strings in realistic models is made and reveals that strings are expected to be not only superconducting in the sense of Witten, but also generically current-carrying, either at the GUT scale or at the electroweak scale. This applies to any GUT string forming model leading to the standa

V. S. Fadin, R. Fiore, A. Quartarolo

$s$-channel discontinuity of quark-quark scattering amplitude with gluon quantum numbers in the $t$ channel and negative signature is calculated in the Regge kinematical region in the two-loop approximation. Using this discontinuity and assuming that the Regge asymptotic behaviour is given by the Reggeized gluon contribution, we calculate the gluon trajector

N. V. Krasnikov

We discuss the phenomenology of colour scalar octets. Namely, we consider the discovery potential of scalar octets at LEP, FNAL and LHC. Scalar octets decay mainly into two gluons and new hadrons composed from scalar colour octets are rather long lived $(Γ\leq O(10)Kev)$. For the scalar octet masses $M \geq O(50)Gev$ scalar octets producing at FNAL or LHC de

S. Y. Choi, K. Hagiwara

We probe the top-quark electric dipole moment (EDM) in top-quark pair production via photon-photon fusion at a photon linear collider. We show how linearly-polarized photon beams can be used to extract information on the top-quark EDM without the use of complicated angular correlations of top-quark decay products. If the luminosity of the laser back-scattere

A. A. Gvozdev, N. V. Mikheev, L. A. Vassilevskaya

The radiative decay of ultrarelativistic massive neutrino $ν_i \rightarrow ν_j γ$ is investigated in electromagnetic fields in the framework of the Standard Model with lepton mixing. Estimates of the decay probability and ``decay cross-section&#39;&#39; for accelerator neutrinos of high energies in the electric field of nucleus permit one to discuss the gene

B. Holdom

A new massive gauge boson (X) coupling to the third family produces a tantalizing pattern of deviations away from the standard model. These include increasing Gamma_b/Gamma_h and decreasing the alpha_s(M_Z) extracted from Gamma_h/Gamma_ell. We indicate how the X boson may be related to a dynamical origin of the top mass.

T. DeGrand, A. Hasenfratz, P. Hasenfratz, F. Niedermayer

In this paper (the second of a series) we extend our calculation of a classical fixed point action for lattice $SU(3)$ pure gauge theory to include gauge configurations with large fluctuations. The action is parameterized in terms of closed loops of link variables. We construct a few-parameter approximation to the classical FP action which is valid for short

T. DeGrand, A. Hasenfratz, P. Hasenfratz, F. Niedermayer

In this paper (the first of a series) we describe the construction of fixed point actions for lattice $SU(3)$ pure gauge theory. Fixed point actions have scale invariant instanton solutions and the spectrum of their quadratic part is exact (they are classical perfect actions). We argue that the fixed point action is even 1--loop quantum perfect, i.e. in its

F. Csikor, Z. Fodor, J. Hein, J. Heitger

In our nonperturbative lattice investigation we study the interface tension of the finite-temperature electroweak phase transition. In this analysis the Higgs mass has been chosen to be about $35$ GeV. At the transition point of a finite volume system, tunnelling between the symmetric and the Higgs phase takes place. This phenomenon leads to a splitting of t

H. Gausterer, C. B. Lang

The lattice regularized Schwinger model for one fermion flavor and in the strong coupling limit is studied through its equivalent representation as a restricted 8-vertex model. The Monte Carlo simulation on lattices with torus-topology is handicapped by a severe non-ergodicity of the updating algorithm; introducing lattices with spherelike topology avoids th

C. Alexandrou, A. Galli

We calculate the $\bar{s}s$ condensate in the D - and B - mesons using the unquenched hopping parameter expansion at infinite coupling for the Wilson lattice action. We discuss the phenomenological relevance of our result.

Melvyn J. Shochet

Summary of the 10th Topical Workshop on Proton-Antiproton Collider Physics, Fermilab, May 9-13, 1995.