November 1993 arXiv papers — page 5

Matt Visser

Calculating the van Vleck determinant in traversable wormhole spacetimes is an important ingredient in understanding the physical basis behind Hawking's chronology protection conjecture. This paper presents extensive computations of this object --- at least in the short--throat flat--space approximation. An important technical trick is to use an extensio

David Kastor, Jennie Traschen

We study quantum mechanical and classical stability properties of Reissner-Nordstrom deSitter spacetimes, which describe black holes with mass $M$ and charge $Q$ in a background with cosmological constant $Λ\ge 0$. There are two sources of particle production in these spacetimes; the black hole horizon and the cosmological horizon. A scattering calculation i

J. D. Reger, A. P. Young

We describe results of Monte Carlo simulations on a model that seems to have the necessary ingredients to describe a disordered type-II superconductor in a magnetic field. We compute the free energy cost to twist the direction of the phase of the condensate and analyze the results by finite-size scaling. The results show convincingly that the model has diffe

A. J. Millis, H. Monien

We investigate the relevance to the physics of underdoped YBa$_2$Cu$_3$O$_{\rm 6+x}$ and YBa$_2$Cu$_4$O$_8$ of the quantum critical point which occurs in a model of two antiferromagnetically coupled planes of antiferromagnetically correlated spins. We use a Schwinger boson mean field theory and a scaling analysis to obtain the phase diagram of the model and

Hiroki Nakano, Minoru Takahashi

A modified spin-wave theory is applied to the one-dimensional quantum Heisenberg model with long-range ferromagnetic interactions. Low-temperature properties of this model are investigated. The susceptibility and the specific heat are calculated; the relation between their behaviors and strength of the long-range interactions is obtained. This model includes

Edward W. Kolb, Igor I. Tkachev

The $(3+1)$-dimensional evolution of an inhomogeneous axion field configuration around the QCD epoch is studied numerically, including important non-linear effects due to the attractive self-interaction. It is found that axion perturbations on scales corresponding to causally disconnected regions at $T \sim 1 \, {\rm GeV}$ can lead to very dense pseudo-solit

P. D. Morley

I show that the braking index, $N$, a fundamental pulsar experimental quantity, naturally differs from the canonical value of 3 by terms which involve mass accretion. Using the measured values of $N$ for PSR1509-58 and PSR0531+21, I determine that for constant density neutron stars their present mass accretion rates are $(3.10\pm.51)\times10^{-5}$ M year$^{-

P. D. Morley

Non-static gravitational fields generally introduce frequency shifts when bending light. In this paper, I discuss the frequency shifts induced in the bending of light by moving masses. As examples, I treat the recently discovered high-velocity pulsar PSR 2224+65 and a typical Einstein ring.

Nichol, Collins

In this paper, we investigate the effects of galactic extinction close to the south galactic pole and plate--to--plate matching errors. These represent the most probable systematic errors within the Edinburgh/Durham Southern Galaxy Catalogue (EDSGC) which could affect the angular correlation function. The distribution of extinction within the EDSGC area was

Nichol, Briel, Henry

We present here the Spatial Two--Point Correlation Function for a complete sample of 67 X--ray selected Abell clusters of galaxies. We find a correlation length of $16.1\pm3.4\mpc$ with no significant clustering beyond $\simeq40\mpc$. This is the lowest uncorrected value for the correlation length ever derived from the Abell catalogue of clusters. In additio

C. L. Bennett, D. J. Fixsen, G. Hinshaw, J. C. Mather

The FIRAS instrument on the COBE satellite has conducted an unbiased survey of the far-infrared emission from our Galaxy. The first results of this survey were reported by Wright et al. (1991). We report the results of new analyses of this spectral survey, which includes emission lines from 158 um C+, 122 um and 205 um N+, 370 um and 609 um C, and CO J=2-1 t

M. Milgrom

Lo, Sargent, and Young (1993) have recently concluded that the masses of some dwarf galaxies, as deduced by the modified dynamics (MOND) from the observed velocity dispersions, are systematically smaller than the observed masses, by a factor of ten or more. We show here that the MOND mass estimator used by Lo et al. is smaller than the proper expression, by

J. Winkelmann

We investigate for which linear-algebraic groups (over the complex numbers or any local field) there exists subgroups which are dense in the Zariski topology, but discrete in the Hausdorff topology. For instance, such subgroups exist for every non-solvable complex group.

John David Crawford

Bifurcation problems in which periodic boundary conditions or Neumann boundary conditions are imposed often involve partial differential equations that have Euclidean symmetry. As a result the normal form equations for the bifurcation may be constrained by the ``hidden'' Euclidean symmetry of the equations, even though this symmetry is broken by the

Vittorio Del Duca, Carl R. Schmidt

We examine dijet production at large rapidity intervals at Tevatron energies, by using the theory of Lipatov and collaborators which resums the leading powers of the rapidity interval. We analyze the growth of the Mueller-Navelet $K$-factor in this context and find it to be negligible. However, we do find a considerable enhancement of jet production at large

S. Kumano

1) We discuss a sum rule of the tensor structure function $b_1(x)$ for spin-one hadrons along with the Gottfried sum rule. Both sum rules are similar in the sense that they are phenomenological ones based on a naive parton model. As the Gottfried sum rule became useful for studying SU(2)$_{flavor}$ breaking in antiquark distributions, the $b_1$ sum rule coul

A. O. Barvinsky

The reduction algorithms for functional determinants of differential operators on spacetime manifolds of different topological types are presented, which were recently used for the calculation of the no-boundary wavefunction and the partition function of tunnelling geometries in quantum gravity and cosmology.

A. O. Barvinsky, A. Yu. Kamenshchik

We present a theory of tunnelling geometries originating from the no-boundary quantum state of Hartle and Hawking. We reformulate the no-boundary wavefunction in the representation of true physical variables and calculate it in the one-loop approximation. For this purpose a special technique is developed, which reduces the formalism of complex tunnelling geo

Elliott Lieb

Paper: cond-mat/9311033 The Hubbard model of interacting electrons, like the Ising model of spin-spin interactions, is the simplest possible model displaying many ``real world'' features, but it is much more difficult to analyze qualitatively than the Ising model. After a third of a century of research, we are still not sure about many of its basic p

W. Koepf, E. M. Henley

In this work, we investigate the question, whether the conventional analysis of the electromagnetic form factors of the nucleon, evaluated in the framework of the cloudy bag model (CBM) or other chirally invariant hybrid quark models utilizing the same philosophy, is gauge invariant. In order to address that point, we first formulate the CBM in a style that

R. Altmeyer, M. Goeckeler, R. Horsley, E. Laermann

A lattice calculation of the pi-N sigma term is described using dynamical staggered fermions. Preliminary results give a sea term comparable in magnitude to the valence term.

A. Yu. Alekseev

We consider the moduli space of flat connections on the Riemann surface with marked points. The new efficient parametrization is suggested and used to construct an integrable model on the moduli space. A family of commuting Hamiltonians is extracted from the trace of the transfer matrix built from the Wilson line observables of the Chern-Simons theory. Our m

B. Ehrnsperger, L. Mankiewicz, A. Schäfer

We present an explicit OPE analysis for the first moment of $g_1$ up to order $M^2/Q^2$. This result allows to calculate power corrections to the Bjorken and Ellis--Jaffe sum rules.

M. Boiti, F. Fempinelli

The Kadomtsev--Petviashvili I (KPI) is considered as a useful laboratory for experimenting new theoretical tools able to handle the specific features of integrable models in $2+1$ dimensions. The linearized version of the KPI equation is first considered by solving the initial value problem for different classes of initial data. Properties of the solutions i

M. Boiti, L. Martina, F. Pempinelli

Recently it has been discovered that some nonlinear evolution equations in 2+1 dimensions, which are integrable by the use of the Spectral Transform, admit localized (in the space) soliton solutions. This article briefly reviews some of the main results obtained in the last five years thanks to the renewed interest in soliton theory due to this discovery. Th

B. Harms, Y. Leblanc

We review briefly the thermodynamical interpretation of black hole physics and discuss the problems and inconsistencies in this approach. We provide an alternative interpretation of black holes as quantum objects and investigate the statistical mechanics of a gas of such objects in the microcanonical ensemble. We argue that the theory of black holes has the

M. Leblanc, R. MacKenzie, P. K. Panigrahi, R. Ray

Analysing a 3+1 dimensional model with four-Fermi interactions, we show that topological $\BF$ terms (both abelian and non-abelian) can be induced radiatively by massive fermions at the one-loop level. It is further pointed out that a mechanism of photon (or non-abelian gauge field) mass generation distinct from the usual Higgs mechanism, through the $\BF$ t

D. V. Gluschenkov, A. V. Lyakhovskaya

Pairing between the universal enveloping algebra $U_q(sl(2))$ and the algebra of functions over $SL_q(2)$ is obtained in explicit terms. The regular representation of the quantum double is constructed and investigated. The structure of the root subspaces of the Casimir operator is revealed and described in terms of $SL_q(2)$ elements.

D. J. Gross, W. Taylor

A review is given of recent research on two-dimensional gauge theories, with particular emphasis on the equivalence between these theories and certain string theories with a two-dimensional target space. Some related open problems are discussed.

Michael A. Doncheski, Stephen Godfrey

We calculate the resolved photon contribution to leptoquark production at $eγ$ colliders for the center of mass energies $\sqrt s=500$~GeV and 1~TeV. We also calculate the resolved photon contribution to leptoquark production at $e^+ e^-$ colliders for the center of mass energies $\sqrt{s} = 1$~and~2~TeV. In both cases we find that these contributions are co

M. Sutherland

A simple model of Omega_Q and Omega_Q^(*) baryons containing one heavy quark Q is constructed. Amplitudes are represented by loop graphs with one line for the heavy quark and another for the light degrees of freedom. The latter are modelled as a freely-propagating vector particle interacting nonlocally with the heavy baryon and a free heavy quark. It is argu

Herbi Dreiner

This talk is based on work performed with Graham Ross and is a very concise summary of our soon to be published paper. Here we present a revision of the analysis of sphaleron baryon-number violating processes in the standard model including lepton-mass effects. We find the surprising result that a GUT-scale matter-asymmetry can survive the $B$ and $L$ violat

J. Papavassiliou, C. Parrinello

Motivated by the possibility of experimental determination of top quark form factors in upcoming e+ e- experiments, as recently discussed by Atwood and Soni, we show at the one loop level that the conventionally defined magnetic dipole moment (MDM) form factor of the top quark is gauge dependent, in the class of renormalizable ($R_ξ$) gauges. We explicitly c

R. Peschanski

This contribution contains a summary of the Krakow meeting on Soft Physics and Fluctuations. It emphasizes both the experimental and the theoretical investigations on correlations/fluctuations and intermittency in multi-particle processes and discusses of the present status of this concept. A clarification of the main open questions in this field of research

Andreas Blumhofer

Quadratic divergencies which lead to the usual fine-tuning or hierarchy problem are discussed in top condensation models. As in the Standard Model a cancellation of quadratic divergencies is not possible without the boson contributions in the radiative corrections which are absent in lowest order of an $1/N_c$-expansion. To deal with the cancellation of quad

David B. Kaplan, Martin Schmaltz

Grand unified theories with fermions transforming as irreducible representations of a discrete nonabelian flavor symmetry can lead to realistic fermion masses, without requiring very small fundamental parameters. We construct a specific example of a supersymmetric GUT based on the flavor symmetry $Δ(75)$ --- a subgroup of $SU(3)$ --- which can explain the ob

Su H. Lee, T. Hatsuda, G. A. Miller

QCD sum rules are used to compute the first few moments of the mesonic quark momentum. Transverse, longitudinal and mixed transverse-longitudinal components are examined. The transverse size of the pion is shown to be dictated by the gluon condensate, even though the mass and the longitudinal distribution are dominated by the quark condensate. The implicatio

Aram Antaramian, Lawrence J. Hall, Andrija Rašin

Stringent bounds on baryon and lepton number violating interactions have been derived from the requirement that such interactions, together with electroweak instantons, do not destroy a cosmological baryon asymmetry produced at an extremely high temperature in the big bang. While these bounds apply in specific models, we find that they are generically evaded

Sonali Mukherjee, Hisao Nakanishi, Norman H. Fuchs

We study the dynamical exponents $d_{w}$ and $d_{s}$ for a particle diffusing in a disordered medium (modeled by a percolation cluster), from the regime of extreme disorder (i.e., when the percolation cluster is a fractal at $p=p_{c}$) to the Lorentz gas regime when the cluster has weak disorder at $p>p_{c}$ and the leading behavior is standard diffusion. A

M. D. Rintoul, Jangnyeol Moon, Hisao Nakanishi

A comprehensive numerical study of self-avoiding walks (SAW's) on randomly diluted lattices in two and three dimensions is carried out. The critical exponents $ν$ and $χ$ are calculated for various different occupation probabilities, disorder configuration ensembles, and walk weighting schemes. These results are analyzed and compared with those previousl

E. Canessa, Wei Wang

Alternative to the Poisson growth model, numerical simulations of the two-dimensional biharmonic equation $\nabla^{2*2} u =0$ show that a transition from dense to multibranched growth is a consequence of the different coupling between displacements on the pattern formation of fractal aggregates.

G. Hinshaw, A. Kogut, K. M. Gorski, A. J. Banday

We compute the three-point temperature correlation function of the {\it COBE} Differential Microwave Radiometer (DMR) first-year sky maps to search for non-Gaussian temperature fluctuations. The level of fluctuations seen in the computed correlation function are too large to be attributable solely to instrument noise. However the fluctuations are consistent

Vladimir Skarzhinsky, Diego Harari, Ulf Jasper

We evaluate the cross section for electron-positron pair production by a single high energy photon in the space-time of a static, straight cosmic string. Energy and momentum conservation precludes this process in empty Minkowski space. It happens around a cosmic string, in spite of the local flatness of the metric, as a consequence of the conical structure o

M. P. Pato, C. A. Nunes, C. L. Lima, M. S. Hussein

A Deformed Gaussian Orthogonal Ensemble (DGOE) which interpolates between the Gaussian Orthogonal Ensemble and a Poissonian Ensemble is constructed. This new ensemble is then applied to the analysis of the chaotic properties of the low lying collective states of nuclei described by the Interacting Boson Model (IBM). This model undergoes a transition order-ch

R. Machleidt, G. Q. Li

The sensitivity of the deuteron and of $pp$ scattering to the $πNN$ and $ρNN$ coupling constants is investigated systematically. We find that the deuteron can be described about equally well with either {\it large $π$ and $ρ$} or {\it small $π$ and $ρ$} coupling constants. However, $pp$ scattering clearly {\it requires} the strong $ρ$, but favors the weak $π

D. C. Cabra, C. M. Naón

We study the two-dimensional Ising model with a defect line and evaluate multipoint energy correlation functions using non-perturbative field-theoretical methods. We also discuss the evaluation of the two spin correlator on the defect line.

A. Restuccia, J. Stephany

We describe a canonical covariant approach to the quantization of the Green-Schwarz superstring. The approach is first applied to the canonical covariant quantization of the Brink and Schwarz superparticle. The Kallosh action is obtained in this case, with the correct BRST cohomology.

L. Bonora, C. S. Xiong

We discuss a differential integrable hierarchy, which we call the (N, M)$--th KdV hierarchy, whose Lax operator is obtained by properly adding $M$ pseudo--differential terms to the Lax operator of the N--th KdV hierarchy. This new hierarchy contains both the higher KdV hierarchy and multi--field representation of KP hierarchy as sub--systems and naturally ap

M. Ruiz--Altaba

These notes correspond rather accurately to the translation of the lectures given at the Fifth Mexican School of Particles and Fields, held in Guanajuato, Gto., in December~1992. They constitute a brief and elementary introduction to quantum symmetries from a physical point of view, along the lines of the forthcoming book by C. Gómez, G. Sierra and myself.

A. H. Chamseddine, J. Fröhlich

We review the construction of particle physics models in the framework of non-commutative geometry. We first give simple examples, and then progress to outline the Connes-Lott construction of the standard Weinberg-Salam model and our construction of the SO(10) model. We then discuss the analogue of the Einstein-Hilbert action and gravitational matter couplin

T. J. Hollowood, J. L. Miramontes, J. Sanchez Guillen

The non-isospectral symmetries of a general class of integrable hierarchies are found, generalizing the Galilean and scaling symmetries of the Korteweg--de Vries equation and its hierarchy. The symmetries arise in a very natural way from the semi-direct product structure of the Virasoro algebra and the affine Kac--Moody algebra underlying the construction of

Gary McCartor, David G. Robertson

Light-cone quantization of gauge field theory is considered. With a careful treatment of the relevant degrees of freedom and where they must be initialized, the results obtained in equal-time quantization are recovered, in particular the Mandelstam-Leibbrandt form of the gauge field propagator. Some aspects of the ``discretized'' light-cone quantizat

M. Gleiser, R. O. Ramos

We examine the nonequilibrium dynamics of a self-interacting $λϕ^4$ scalar field theory. Using a real time formulation of finite temperature field theory we derive, up to two loops and $O(λ^2)$, the effective equation of motion describing the approach to equilibrium. We present a detailed analysis of the approximations used in order to obtain a Langevin-like

J. L. Lopez, D. V. Nanopoulos, G. T. Park, A. Zichichi

We explore the one-loop electroweak radiative corrections in $SU(5)\times U(1)$ supergravity via explicit calculation of vacuum-polarization and vertex-correction contributions to the $ε_1$ and $ε_b$ parameters. Experimentally, these parameters are obtained from a global fit to the set of observables $Γ_{l}, Γ_{b}, A^{l}_{FB}$, and $M_W/M_Z$. We include $q^2

Nguyen Ai Viet

A new supersymmetry is proposed for hadrons containing a single heavy quark. This supersymmetry is based on a new approximation to those hadrons, which we would consider as a further step beyond the spectator light diquark model of baryons. The heavy diquark effective theory is constructed by the techniques introduced in a different context by Georgi and Wis

Boris Kopeliovich

Contrary to widespread opinion, color transparency (CT) brings essential ambiguity to, rather than helps in, study of the nuclear spectral function in quasielastic lepton scattering, $A(l,l'p)A'$, at high $Q^2$. Although the nuclear attenuation vanishes, the final state interaction (FSI) of a small-size ejectile wave packet, propagating through nucle

H. Leutwyler

The properties of the effective field theory relevant for the low energy structure generated by the Goldstone bosons of a spontaneously broken symmetry are reexamined. It is shown that anomaly free, Lorentz invariant theories are characterized by a gauge invariant effective Lagrangian, to all orders of the low energy expansion. The paper includes a discussio

Mario Everaldo de Souza

By means of a general classification of the different kinds of matter which were formed along the universal expansion, the paper shows that the force of nature form a chain from the world of the prequarks to the galaxies. It is shown that matter has a generalized structured state characterized by some degree of order and by a Lennard-Jones effective potentia

Chilong Lin, Chien-er Lee, Yeou-Wei Yang

We consider a two Higgs-doublet model with $S_3$ symmetry, which implies a $π\over 2$ rather than 0 relative phase between the vacuum expectation values $<Φ_1>$ and $<Φ_2>$. The corresponding Feynman rules are derived accordingly and the transformation of the Higgs fields from the weak to the mass eigenstates includes not only an angle rotation but also a ph

Chilong Lin, Chien-er Lee, Yeou-Wei Yang

The spontaneous CP-violation in three kinds of extension of the standard model are investigated. We find that if no additional symmetry is introduced to reduce the number of coefficients, then all three extended models possess the spontaneous CP violation (SCPV) in the Higgs potential. When symmetry under which the doublets transform as $Φ_1 \to Φ_1$ and $Φ_

Paolo M. Gensini, Galileo Violini

Present evidence on baryon axial--vector couplings is reviewed, the main emphasis being on internal consistency between asymmetry and rate data. A complete account of all {\sl small} terms in the Standard Model description of these latter leads to {\sl both} consistency {\sl and} evidence for breaking of flavour SU(3) in the axial couplings of octet baryons.

V. Barger, M. S. Berger, P. Ohmann

We examine the spectrum of supersymmetric particles predicted by grand unified theoretical (GUT) models where the electroweak symmetry breaking is accomplished radiatively. We evolve the soft supersymmetry breaking parameters according to the renormalization group equations (RGE). The minimization of the Higgs potential is conveniently described by means of

Howard D. Trottier

A factorization theorem for $P$-wave quarkonium production, recently derived by Bodwin, Braaten, Yuan and Lepage, is applied to $Υ\to χ_{cJ} + X$, where $χ_{cJ}$ labels the ${}^3 P_J$ charmonium states. The widths for $χ_{cJ}$ production through color-singlet $P$-wave and color-octet $S$-wave $c \bar c$ subprocesses are computed each to leading order in $α_s

T. Thiemann

We introduce a reduced model for a real sector of complexified Ashtekar gravity that does not correspond to a subset of Einstein&#39;s gravity but for which the programme of canonical quantization can be carried out completely, both, via the reduced phase space approach or along the lines of the algebraic quantization programme.\\ This model stands in a cert

Guillermo A. Mena Marugan

Using Ashtekar variables, we analyze Lorentzian and Euclidean gravity in vacuum up to a constant conformal transformation. We prove that the reality conditions are invariant under a Wick rotation of the time, and show that the compatibility of the algebra of commutators and constraints with the involution defined by the reality conditions restricts the possi

J. Fernando Barbero

I show in this letter that it is possible to construct a Hamiltonian description for Lorentzian General Relativity in terms of two real $SO(3)$ connections. The constraints are simple polynomials in the basic variables. The present framework gives us a new formulation of General Relativity that keeps some of the interesting features of the Ashtekar formulati

Oleg A. Fonarev

A brief review of the Wigner functions method in curved space-time. Contribution to the 3rd International Wigner Symposium, 5th-11th September 1993, Oxford, UK.

Kihong Kim, Ross H. McKenzie, John W. Wilkins

Quasi-one-dimensional Peierls systems with quantum and thermal lattice fluctuations can be modeled by a Dirac-type equation with a Gaussian-correlated off-diagonal disorder. A powerful new method gives the exact disorder-averaged Green function used to compute the optical conductivity. The strong subgap tail of the conductivity has a universal scaling form.

Sutapa Mukherji, Somendra M. Bhattacharjee

We propose a model for two $(d+1)$-dimensional directed polymers subjected to a mutual $δ$-function interaction with a random coupling constant, and present an exact renormalization group study for this system. The exact $β$-function, evaluated through an $ε(=1-d)$ expansion for second and third moments of the partition function, exhibits the marginal releva

S. D. Brorson, R. Buhleier, J. O. White, I. E. Trofimov

We measure the transmission of THz pulses through thin films of YBCO at temperatures between 10K and 300K. The pulses possess a useable bandwidth extending from 0.1 -- 1.5 THz (3.3 cm^-1 -- 50 cm^-1). Below T_c we observe pulse reshaping caused by the kinetic inductance of the superconducting charge carriers. From transmission data, we extract values of the

Alexander O. Gogolin, Nikolai V. Prokof&#39;ev

The general expression for the persistent current of 1D noninteracting electrons in a disorder potential with smooth scattering data is derived for zero temperature. On the basis of this expression the parity effects are discussed. It is shown that the electron-electron interaction may give rise to an unusual size-dependence of the current amplitude due to r

David A. Egolf, Henry S. Greenside

For one-dimensional phase-turbulent solutions of the Kuramoto-Sivashinsky equation with rigid boundary conditions, we show that there is a substantial variation of the correlation time~$τ_c(x)$ with spatial position $x$ in moderately large systems of size $L$. These results suggest that some time-averaged properties of spatiotemporal chaos do not become homo

Lev Kofman, Edmund Bertschinger, James M. Gelb, Adi Nusser

We study the quasilinear evolution of the one-point probability density functions (PDFs) of the smoothed density and velocity fields in a cosmological gravitating system beginning with Gaussian initial fluctuations. Our analytic results are based on the Zel&#39;dovich approximation and laminar flow. A numerical analysis extends the results into the multistre

Lev Kofman

The evolution of probability distribution functions (PDFs) of continuous density, velocity and velocity derivatives ( deformation tensor) fields in the theory of cosmological gravitational instability are considered. We show that in the Newtonian theory the dynamical equations cannot be reduced to the closed set of Lagrangian equations. Since continuous fiel

Giovanni Zamorani

Invited review talk given at the Meeting on &#34;Extragalactic Background Radiation: A meeting in honor of Riccardo Giacconi&#34; Baltimore, May 18-20, 1993 Ro be published by Cambridge University Press

Robert E. Rutledge, Walter H. G. Lewin

Quashnock and Lamb (1993) defined a sub-sample of Gamma-ray Bursts (GRBs) from the publicly available BATSE database which shows clumping toward the galactic plane, and concluded that all GRBs are galactic in origin. The selection of these bursts (duplicated in this work in Sample 1) involved a peak countrate (in counts s-1) uncorrected for aspect. We assert

Atsushi Moriwaki

Let F be a function field of one variable over an algebraically closed field of characteristic zero, X a geometrically irreducible smooth projective variety over F, and L a line bundle on X. In this note, we will prove that if the contangent bundle of X is ample and X is non-isotrivial, then there are a proper closed algebraic set Y of X and a constant A > 0

Le Viet Dung, Nguyen Ai Viet

It is shown that the number of independent weak form factors collapses if the heavy diquark exists inside the baryons containing a single heavy quark. The relations between the weak form factors are quite different in the case of light diquark. So a careful analysis on the future data of the weak form factors would clarify that in those baryons the correlati

S. Ambrosanio, B. Mele

Present limits on the top mass from LEP1 and Tevatron point to a top quark that is considerably heavier than the $W$ vector boson in the standard model. Hence, e+e- colliders with \sqrt{s} \simeq 300 GeV (the c.m. energy foreseen at the first phase of the Next Linear e+e- Collider) could be well below the energy threshold for real top-pair production. We arg

A. A. Tseytlin

We consider a class of sigma models that appears from a generalisation of the gauged WZW model parametrised by a constant matrix $Q$. Particular values of $Q$ correspond to the standard gauged WZW models, chiral gauged WZW models and a bosonised version of the non-abelian Thirring model. The condition of conformal invariance of the models (to one loop or $1/

Calvin W. Johnson, Joseph N. Ginocchio

We discuss a general, exact (in that matrix elements are preserved) mapping of fermion pairs to bosons, and find a simple factorization of the boson representation of fermion operators. This leads to boson Hamiltonians that are Hermitian and finite, with no more than two-body operators if the fermion Hamiltonian has at most two-body operators, and one-body b

Saharon Shelah, Lee Stanley

Assuming 0# does not exist, we present a combinatorial approach to Jensen&#39;s method of coding by a real. The forcing uses combinatorial consequences of fine structure (including the Covering Lemma, in various guises), but makes no direct appeal to fine structure itself.

P. Gaete, J. Gamboa, I. Schmidt

Two-dimensional quantum cromodynamics in the light-front frame is studied following hamiltonian methods. The theory is quantized using the path integral formalism and an effective theory similar to the Nambu-Jona Lasinio model is obtained. Confinement in two dimensions is derived analyzing directly the constraints in the path integral.

K. S. Gupta, R. J. Henderson, S. G. Rajeev, O. T. Turgut

We study a model of quantum Yang-Mills theory with a finite number of gauge invariant degrees of freedom. The gauge field has only a finite number of degrees of freedom since we assume that space-time is a two dimensional cylinder. We couple the gauge field to matter, modeled by either one or two nonrelativistic point particles. These problems can be solved

M. Temple-Raston

We introduce a topological field theory with a Bogomol&#39;nyi structure permitting BPS electric, magnetic and dyonic monopoles. From the general arguments given by Montonen and Olive the particle spectrum and mass compare favourably with that of the intermediate vector bosons. In most, if not in all, of its essential features the topological field theory in

M. Chaichian, A. P. Demichev

We construct quantum deformation of Poincaré group using as a starting point $SU(2,2)$ conformal group and twistor-like definition of the Minkowski space. We obtain quantum deformation of $SU(2,2)$ as a real form of multiparametric $GL(4,C)_{q_{ij},r}$. It is shown that Poincaré subgroup exists for special nonstandard one-parametric deformation only, the def

Carl M. Bender, Stefan Boettcher

A recently-proposed technique, called the dimensional expansion, uses the space-time dimension $D$ as an expansion parameter to extract nonperturbative results in quantum field theory. Here we apply dimensional-expansion methods to examine the Ising limit of a self-interacting scalar field theory. We compute the first few coefficients in the dimensional expa

Jens Hoppe

A non-parametric gauge for supermembranes is introduced which substantially simplifies previous treatments and directly leads to the supersymmetric extension of a Karman-Tsien gas.

Ezer Melzer

The finite-volume spectrum of an integrable massive perturbation of a rational conformal field theory interpolates between massive multi-particle states in infinite volume (IR limit) and conformal states, which are approached at zero volume (UV limit). Each state is labeled in the IR by a set of `Bethe Ansatz quantum numbers&#39;, while in the UV limit it is

J. W. Goodison, D. J. Toms

We consider quon statistics in a dynamically evolving curved spacetime in which prior to some initial time and subsequent to some later time is flat. By considering the Bogoliubov transformations associated with gravitationally induced particle creation, we find that the consistent evolution of the generalized commutation relations from the first flat region

Ian Affleck, Jacob Sagi

Monopole-mediated baryon number violation, the Callan-Rubakov effect, is reexamined using boundary conformal field theory techniques. It is shown that the low-energy behaviour is described simply by free fermions with a conformally invariant boundary condition at the dyon location. When the number of fermion flavours is greater than two, this boundary condit

Dinesh K. Srivastava, Charles Gale

Two-photon intensity interferometry is shown to provide an accurate measurement of lifetime of quark-gluon plasma created in ultra-relativistic heavy ion collisions via the difference of outward and sidewardcorrelation radii. Under the assumption of a longitudinal, boost invariant expansion of the plasma, we obtain analytical expressions for the correlations

T. G. Rizzo

We explore the sensitivity of the on-going Tevatron search for charged, right-handed gauge bosons, $W_R^{\pm}$, to various model dependent assumptions such as the magnitude of the $SU(2)_R$ gauge coupling, the values of the right-handed Kobayashi-Maskawa mixing matrix elements, $(V_R)_{ij}$, and the nature of the right-handed neutrino. These results also hav

H. Leutwyler

Chiral perturbation theory is extended to nonrelativistic systems with spontaneously broken symmetry. In the effective Lagrangian, order parameters associated with the generators of the group manifest themselves as effective coupling constants of a topological term, which is gauge invariant only up to a total derivative. In the case of the ferromagnet, a ter

Ina Sarcevic

We present results of calculations of the total and jet photoproduction cross sections at HERA and Fermilab energies$^1$. The calculations take into account the high-energy QCD structure of the photon and are performed for different photon structure functions. We discuss how recent measurements of the total photoproduction cross section at HERA energies$^2$

H. Veltman

The level of sensitivity of the processes $γγ\to ZZ$, $γγ\to W^+W^-$ and $γγ\to t\bar t$ to the Higgs sector of the Standard Model Lagrangian in the energy region between 200 GeV and 1 TeV is examined. The elementary Higgs boson is taken to have a mass less than 1 TeV. Sizeable effects are found in the $ZZ$ and $t\bar t$ channels if the incoming photons have

M. Cacciari, M. Greco

The production of heavy quarks at large $\pt$ ($\pt\gg m$) in hadronic collisions is considered. The analysis is carried out in the framework of perturbative fragmentation functions, thereby allowing a resummation at the NLO level of final state large mass logarithms of the kind $\log(\pt/m)$. The case of $b$-quark production is considered in detail. The res

Carsten Grosse-Knetter

The HLE theorem is proven for effective Lagrangians with arbitrary interactions of scalars, fermions, massless and massive vector bosons. This theorem states that the correct Hamiltonian path intergral formalism is equivalent to the convenient Lagrangian path integral ansatz. In particular, this theorem is valid for effective gauge theories, which justifies

A. Ilakovac, B. A. Kniehl, A. Pilaftsis

The possibility of observing CP violation in the decays of Higgs particles into top-quark, W- and Z-boson pairs induced by heavy Majorana neutrinos is discussed. In the context of minimal &#34;see-saw&#34; models with interfamily mixings, we find that Majorana neutrinos may give rise to sizable CP-odd effects at the one-loop electroweak order. We present num

A. Datta, M. Guchait, A. Pilaftsis

The possibility of discovering heavy Majorana neutrinos and lepton number violation via the like sign dilepton signal at hadron super- colliders is investigated. The cross-sections for the production of these neutrinos singly as well as in pairs are computed both in three and four generation scenarios within the framework of the gauge group $SU(2)_L \otimes