March 1995 arXiv papers — page 4

Jonathan Bagger, Konstantin Matchev, Damien Pierce

We present selected results of our program to determine the masses, gauge couplings, and Yukawa couplings of the minimal supersymmetric model in a full one-loop calculation. We focus on the precise prediction of the strong coupling alpha_s(M_Z) in the context of supersymmetric unification. We discuss the importance of including the finite corrections and dem

O. V. Babourova, B. N. Frolov

The harmonicity condition of the curvature 2-form of a pseudo- Riemannian manifold is formulated on the basis of annulment of this form by the de Rham-Lichnerowicz Laplacian. The following theorem is proved: The curvature 2-form of any Einstein manifold is harmonic.

Dirk Ferus, Franz Pedit

This paper studies isometric immersions of space forms by means of a hierarchy of finite dimensional integrable systems in Lax form on loop algebras.

E. A. Bartnik, J. A. Tuszynski, D. Sept

The Davydov model of energy transfer in molecular chains is reconsidered assuming the distance dependence of the exciton hopping term. New equations of motion for phonons and excitons are derived within the coherent state approximation. Solving these nonlinear equations result in the existence of Davydov-like solitons. In the case of a dilatational soliton,

S. A. Janowsky

We describe the spatial structure of particles in the (one dimensional) two-species annihilation reaction A + B --> 0, where both species have a uniform drift in the same direction and like species have a hard core exclusion. For the case of equal initial concentration, at long times, there are three relevant length scales: the typical distance between simil

J. Boronat, J. Casulleras, F. Dalfovo, S. Moroni

The sum rule approach is used to derive upper bounds for the dispersion law $ω_0(q)$ of the elementary excitations of a Bose superfluid. Bounds are explicitly calculated for the phonon-roton dispersion in superfluid $^4$He, both at equilibrium ($ρ=0.02186$ Å$^{-3}$) and close to freezing ($ρ=0.02622$ Å$^{-3}$). The bound $ω_0(q) \le 2S(q)\midχ(q)\mid^{-1}$,

Horatiu Simon

We look for similarity transformations which yield mappings between different one-dimensional reaction-diffusion processes. In this way results obtained for special systems can be generalized to equivalent reaction-diffusion models. The coagulation (A + A -> A) or the annihilation (A + A -> 0) models can be mapped onto systems in which both processes are all

Wlodek Zadrozny

We prove a theorem stating that any semantics can be encoded as a compositional semantics, which means that, essentially, the standard definition of compositionality is formally vacuous. We then show that when compositional semantics is required to be "systematic" (that is, the meaning function cannot be arbitrary, but must belong to some class), it

L. J. Storrie-Lombardi, R. G. McMahon, M. J. Irwin, C. Hazard

We have obtained high signal:to:noise optical spectroscopy at 5Å resolution of 27 quasars from the APM z$>$4 quasar survey. The spectra have been analyzed to create new samples of high redshift Lyman-limit and damped Lyman-$α$ absorbers. These data have been combined with published data sets in a study of the redshift evolution and the column density distrib

Ben Moore, Neal Katz, George Lake

N-body simulations that follow only a collisionless dark matter component have failed to produce galaxy halos or substructure within dense environments. We investigate the `over-merging' problem analytically and with numerical simulations, by calculating dissolution timescales of halos due to physical and artificial dynamical effects. The numerical resol

P. Meszaros, A. Meszaros

We present analytical solutions for the integral distribution of arbitrary bursting or steady source counts as a function of peak photon count rate within Friedmann cosmological models. We discuss both the standard candle and truncated power-law luminosity function cases with a power-law density evolution. While the analysis is quite general, the specific ex

Shrawan Kumar

We give a criterion for smoothness of a point in any Schubert variety in any G/B in terms of the nil Hecke ring.

Pijush K. Ghosh

We consider a nonrelativistic Chern-Simons theory of planar matter fields interacting with the Chern-Simons gauge field in a $SU(N)_{global} \times U(1)_{local}$ invariant fashion. We find that this model admits static zero-energy self-dual soliton solutions. We also present a set of exact soliton solutions. The exact time-dependent solutions are also obtain

Nikita Nekrasov

We show that spin generalization of elliptic Calogero-Moser system, elliptic extension of Gaudin model and their cousins can be treated as a degenerations of Hitchin systems. Applications to the constructions of integrals of motion, angle-action variables and quantum systems are discussed. Explicit formulas for the Lax operator on the higher genus surfaces a

Pavel M. Nadolsky

While EMC-SMC-E142 data sheds new light on the behavior of polarized parton distributions at small and intermediate $x$, it may be also interesting to study valence quark polarizations at large $x$, where spectator quark counting rules and Carlitz-Kaur type models predict different behavior for down quark polarizations. The article examines the possibility o

Michael Engelhardt

The question whether it is necessary to decompactify the gauge eigenvalue degrees of freedom in QCD$_{1+1} $ is addressed. A careful consideration of the dynamics governing these degrees of freedom leads to the conclusion that eigenvalue decompactification is not necessary due to the curvature on the space of eigenvalues.

Kikuo Harigaya

Band structures of C60-polymers are studied changing conjugation conditions and the electron number. We use a Su-Schrieffer-Heeger type semiempirical model. In the neutral C60-polymer, electronic structures change among direct-gap insulator and the metal, depending on the degree of conjugations. The C60-polymer doped with one electron per one molecule is alw

Hisakazu Minakata

A combined analysis of the terrestrial neutrino experiments and the Kamiokande observation of atmospheric neutrino anomaly is performed under the assumption of the existence of dark-matter-mass neutrinos, as suggested by the recent Los Alamos experiment. In the three-flavor mixing scheme of neutrinos it is shown that the constraints from these experiments ar

Eva Silverstein

A four-point function of $E_6$ singlets, of interest in elucidating the moduli space of (0,2) deformations of the quintic string vacuum, is computed using analytic and numerical methods. The conformal field theory amplitude satisfies the requisite selection rules and monodromy conditions, but the integrated string amplitude vanishes. Together with selection

A. Barenco, C. H. Bennett, R. Cleve, D. P. DiVincenzo

We show that a set of gates that consists of all one-bit quantum gates (U(2)) and the two-bit exclusive-or gate (that maps Boolean values $(x,y)$ to $(x,x \oplus y)$) is universal in the sense that all unitary operations on arbitrarily many bits $n$ (U($2^n$)) can be expressed as compositions of these gates. We investigate the number of the above gates requi

S. Majid

We use braided groups to introduce a theory of $*$-structures on general inhomogeneous quantum groups, which we formulate as {\em quasi-$*$} Hopf algebras. This allows the construction of the tensor product of unitary representations up to a quantum cocycle isomorphism, which is a novel feature of the inhomogeneous case. Examples include $q$-Poincaré quantum

Klaus WERNER, Joerg AICHELIN

We recently introduced a completely new way to study ultrarelativistic nuclear scattering by providing a link between the string model approach and a statistical description. A key issue is the microcanonical treatment of hadronizing individual quark matter droplets. In this paper we describe in detail the hadronization of these droplets according to n-body

Jan de Boer, Frederique Harmsze, Tjark Tjin

In this paper it is stressed that there is no {\em physical} reason for symmetries to be linear and that Lie group theory is therefore too restrictive. We illustrate this with some simple examples. Then we give a readable review on the theory finite $W$-algebras, which is an important class of non-linear symmetries. In particular, we discuss both the classic

H. Lu, C. N. Pope, K. W. Xu

It has been shown that certain $W$ algebras can be linearised by the inclusion of a spin--1 current. This provides a way of obtaining new realisations of the $W$ algebras. Recently such new realisations of $W_3$ were used in order to embed the bosonic string in the critical and non-critical $W_3$ strings. In this paper, we consider similar embeddings in $W_{

H. Lu, C. N. Pope, K. W. Xu

In this paper, we construct non-critical BRST operators for matter and Liouville systems whose currents generate two different $W$ algebras. At the classical level, we construct the BRST operators for $W^{\rm M}_{2,s}\otimes W^{\rm L}_{2,s'}$. The construction is possible for $s=s'$ or $s\ge s'+2$. We also obtain the BRST operator for $W^{\rm M}_

L. D. Soloviev

Classical and quantum solutions for the relativistic straight-line string with arbitrary dependence on the world surface curvature are obtained. They differ from the case of the usual Nambu-Goto interaction by the behaviour of the Regge trajectory which in general can be nonlinear. Regularization of the action is considered and comparison with relativistic p

T. Ackermann, J. Tolksdorf

We study Dirac operators acting on sections of a Clifford module ${\cal E}$\ over a Riemannian manifold $M$. We prove the intrinsic decomposition formula for their square, which is the generalisation of the well-known formula due to Lichnerowicz [L]. This formula enables us to distinguish Dirac operators of simple type. For each Dirac operator of this natura

T. Ackermann, J. Tolksdorf

We prove a generalized version of the well-known Lichnerowicz formula for the square of the most general Dirac operator $\widetilde{D}$\ on an even-dimensional spin manifold associated to a metric connection $\widetilde{\nabla}$. We use this formula to compute the subleading term $Φ_1(x,x, \widetilde{D}^2)$\ of the heat-kernel expansion of $\widetilde{D}^2$.

Denis V. Juriev

Nonhamiltonian interaction of hamiltonian systems is considered. Dynamical equations are constructed by use of symmetric designs on Lie algebras. The results of analysis of these equations show that some class of symmetric designs on Lie algebras beyond Jordan ones may be useful for a description of almost periodic, asymptotically periodic, almost asymptotic

I. Royzen

An explanation of the puzzling alignment effect observed in cosmic ray experiments is suggested

El-Hassan KADA, Joseph PARISI

The $J/Ψ$ decay into a baryon pair and a pseudoscalar meson is computed, for some channels, in lowest order in perturbative QCD, modeling the baryon with a quark-diquark system. We use a set of parameters that has been proposed by some authors in order to fit the proton magnetic form factor $G^{p}_{M}$, the angular distribution of protons in the process $γγ\

Leszek Motyka, Kacper Zalewski

A systematic study of a wide class of nonrelativistic models of $b\overline{b}$ quarkonia is described. It is found that the potential $V(r) = 0.706380(\sqrt{r} - \frac{0.460442}{r}) + 8.81715$ (all in GeV) with the $b$-quark mass $m_b = 4.80303$ GeV gives a satisfactory description of the experimental data below the threshold for strong decays ($ χ^2/DF = 6

M. Dahm, R. Jakob, P. Kroll

The modified perturbative approach in which transverse degrees of freedom as well as Sudakov suppressions are taken into account, is applied to $B$ decays into two $π$ mesons. The influence of various model parameters (CKM matrix elements, $B$ decay constant, mesonic wave functions) on the results as well as short distance corrections to the weak Hamiltonian

John P. Costella, Bruce H. J. McKellar

The Foldy-Wouthuysen transformation of the Dirac Hamiltonian is generally taught as simply a mathematical trick that allows one to obtain a two-component theory in the low-energy limit. It is not often emphasized that the transformed representation is the only one in which one can take a meaningful *classical limit*, in terms of particles and antiparticles.

W. Bietenholz, U. -J. Wiese

We perform a renormalization group transformation to construct a lattice theory of chiral fermions. The field variables of the continuum theory are averaged over hypercubes to define lattice fields. Integrating out the continuum variables in perturbation theory we derive a chirally invariant effective action for the lattice fields. This is consistent with th

W. Kerler, C. Rebbi, A. Weber

Monte Carlo simulations of the 4-dimensional compact U(1) lattice gauge theory in the neighborhood of the transition point are made difficult by the suppression of tunneling between the phases, which becomes very strong as soon as the volume of the lattice grows to any appreciable size. This problem can be avoided by making the monopole coupling a dynamical

Gareth J. Cheetham, E. J. Copeland

The time dependent quantum variational principle is emerging as an important means of studying quantum dynamics, particularly in early universe scenarios. To date all investigations have worked within a Gaussian framework. Here we present an improved method which is demonstrated to be superior to the Gaussian approach and may be naturally extended to the fie

P. Mitra

The thermodynamic and euclidean functional integral approaches to black hole entropy are discussed. The existence of some freedom in the definition of the entropy is pointed out and the possibility of a departure from the semiclassical expression discussed in the light of quantum corrections. The semiclassical area dependence of the entropy of matter in the

Ian Marshall, Tudor Ratiu

It is proved that the ring of invariants of the standard smooth completion of a Kac-Moody Lie algebra is functionally generated by two elements: the coefficient of the center and the Killing form.

P. Benassi, W. Frizzera, M. Montagna, G. Viliani

Anelastic light scattering is computed numerically for model disordered systems (linear chains and 2-dimensional site and bond percolators), with and without electrical disorder. A detailed analysis of the vibrational modes and of their Raman activity evidences that two extreme mechanisms for scattering may be singled out. One of these resembles scattering f

K. J. Wiese, F. David

The scaling properties of self-avoiding tethered membranes at the tricritical point (theta-point) are studied by perturbative renormalization group methods. To treat the 3-body repulsive interaction (known to be relevant for polymers), new analytical and numerical tools are developped and applied to 1-loop calculations. These technics are a prerequisite to h

K. Shiokawa, B. L. Hu

Decoherence in quantum systems which are classically chaotic is studied. The Arnold cat map and the quantum kicked rotor are chosen as examples of linear and nonlinear chaotic systems. The Feynman-Vernon influence functional formalism is used to study the effect of the environment on the system. It is well-known that quantum coherence can obliterate many cha

Carlo Graziani, Alice K. Harding, Ramin Sina

We study the resonant divergences that occur in quantum scattering cross-sections in the presence of a strong external magnetic field. We demonstrate that all such divergences may be eliminated by introducing radiative corrections to the leading-order scattering amplitudes. These corrections impose a choice of basis states that must be used in scattering cal

Amotz Shemi

Unidentified extreme UV sources, detected in the {\it EUVE} and {\it ROSAT} WFC all-sky surveys, could be isolated old neutron stars, accreting material from the ISM. The closest neutron stars, that are located in the local ISM bubble of unusually low density, are faint and cool ($L \sim 10^{27} {\rm \ erg \ s^{-1}}$, $T \sles 6 $eV). The extreme UV spectrum

M. Finkelberg, V. Schechtman

This article is a sequel to hep-th/9411050, q-alg/9412017. In Chapter 1 we associate with every Cartan matrix of finite type and a non-zero complex number $ζ$ an abelian artinian category $\FS$. We call its objects {\em finite factorizable sheaves}. They are certain infinite collections of perverse sheaves on configuration spaces, subject to a compatibility

E. Chacon, J. P. Hernandez, P. Tarazona

Theoretical models for the liquid-vapor and metal-nonmetal transitions of alkali fluids are investigated. Mean-field models are considered first but shown to be inadequate. An alternate approach is then studied in which each statistical configuration of the material is treated as inhomogeneous, with the energy of each ion being determined by its local enviro

Mark A. Samuel, John Ellis, Marek Karliner

We present a method of estimating perturbative coefficients in Quantum Field Theory using Pade Approximants. We test this method on various known QCD results, and find that the method works very well.

F. Lizzi, G. Mangano, G. Miele, G. Sparano

In the framework of the Connes-Lott model based on noncommutative geometry, the basic features of a gauge theory in the presence of gravity are reviewed, in order to show the possible physical relevance of this scheme for inflationary cosmology. These models naturally contain at least two scalar fields, interacting with each other whenever more than one ferm

P. Molnar

Numerical evidence for a cosmological version of the Bartnik-McKinnon family of particle-like solutions of the Einstein-Yang-Mills system is presented. Our solutions are also static, but space has the topology of a three-sphere. By adjusting the cosmological constant we found numerically a spherically symmetric solution which can be regarded as an excitation

Elijah Liflyand

The Fourier transform is naturally defined for integrable functrions. Otherwise, it should be stipulated in which sense the Fourier transform is understood. We consider some class of radial and, generally saying, nonintegrable functions. The Fourier transform is calculated as an improper integral and the limit coincides with the Fourier transform in the dist

N. G. Uraltsev

It is shown that large perturbative corrections found previously for semileptonic beauty and charm decays are associated with using inappropriate pole masses. The latter, in the perturbative expansion, suffer from the 1/m_Q infrared renormalon which is absent in the widths, which leads to similar large corrections in m_Q. Pole masses are neither measured dir

Douglas Burke

We prove that every tower of normal filters of height $\gd$ ($\gd$ supercompact) is precipitous assuming that each normal filter in the tower is the club filter restricted to a stationary set. We give an example to show that this assumption is necessary. We also prove that every normal filter can be generically extended to a well-founded $V$-ultrafilter (ass

Thibault Damour, Alexander Vilenkin

String theory abounds with light scalar fields (the dilaton and various moduli) which create a host of observational problems, and notably some serious cosmological difficulties similar to the ones associated with the Polonyi field in the earliest versions of spontaneously broken supergravity. We show that all these problems are naturally avoided if a recent

M. Blagojević, T. Vukašinac

Covariant quantization of theories based on nonlinear extensions of Lie algebras in 2d is studied by using a generalized Lagrangian BRST formalism. The quantum action is constructed to be invariant under the off--shell nilpotent BRST transformations by using a set of independent antifields as auxiliary, nonpropagating variables in the quantum theory. The gen

B. Sazdović

The connection between the Kac-Moody algebras of currents and the chiral symmetries of the two dimensional WZNW model is clarified. It is shown that only the zero modes of the Kac-Moody currents are the first class constraints, and that, consequently, the corresponding gauge symmetries are chiral.

B. O. Kerbikov, Yu. A. Simonov

Chiral symmetry breaking due to instanton-produced fermion zero modes in the confining vacuum is considered. Zero modes provide 'tHooft-type determinant quark interaction, which is bosonized by introduction of auxiliary fields. For three flavours this procedure becomes nontrivial and a method is suggested which allows to derive effective Lagrangian for m

Nobuyuki Ishibashi, Hikaru Kawai

Using the string field theory recently proposed by the authors and collaborators, we give a background independent formulation of rational noncritical string theories with $c\leq 1$. With a little modification of the string field Hamiltonians previously constructed, we obtain string field theories which include various rational noncritical string theories as

Chung Kao, Nikita Stepanov

The prospects of detecting neutral Higgs bosons in the minimal supersymmetric model via their decays into muon pairs at the LHC are investigated. The CMS detector performance is adopted for a realistic study of observability. It is found that the muon pair decay mode might provide a very promising channel to search for the neutral Higgs bosons of minimal sup

Thomas E. Browder, Klaus Honscheid

B mesons are bound states of a b quark and a light anti-quark. While the binding is provided by the strong interaction B mesons can only decay by the weak interaction. Since the top quark mass is large, B mesons are the only mesons containing quarks of the third generation and thus their decays provide a unique opportunity to measure the Cabibbo-Kobayashi-Ma

HIDENAGA YAMAGISHI, ISMAIL ZAHED

We derive a master formula for chiral $SU(2)\times SU(2)$ breaking, based on the Veltman-Bell equations and the Peierls-Dyson relation. Our approach does not rely on the use of the soft pion limit or an expansion around the chiral limit, and yields exact results for on-shell pions. Threshold theorems for $πN\rightarrow πN$, $γN\rightarrow πN$, $πN\rightarrow

M. V. Libanov, D. T. Son, S. V. Troitsky

It has been shown recently that the amplitude of the creation of $n$ real scalar particles by one virtual boson near $n$--particle threshold exhibits exponential behavior at $n\sim1/λ$. We extend this result to the processes of multiparticle production at threshold by two virtual bosons. We find that both the tree--level amplitude and leading--$n$ loop corre

Wolfgang Hollik

The role of the top quark in the Standard Model predictions for electroweak precision observables is reviewed and the implications of the experimental data for the indirect determination of the top mass range is discussed.

B. Grzadkowski, J. F. Gunion

We demonstrate that decay angle correlations in $\taum\taup$ and $t\anti t$ decay modes could allow a determination of whether or not a neutral Higgs boson is a CP eigenstate. Sensitivity of the correlations is illustrated in the case of the $\epem\rta Z \hn$ and $\mupmum\rta \hn$ production processes for a two-doublet Higgs model with CP-violating neutral s

Patrick Peter

Domain walls, arising from the spontaneous breaking of a discrete symmetry, can be coupled to charge carriers. In much the same way as the Witten model for superconducting cosmic string, an investigation is made here in the case of $U(1)\times Z_2 \to U(1)$, where a bosonic charge carrier is directly coupled to the wall-forming Higgs field. All internal quan

F. Halzen, M. C. Gonzalez-Garcia, T. Stelzer, R. A. Vazquez

We calculate the production of 2 b-quark pairs in hadron collisions. Sources of multiple pairs are multiple interactions and higher order perturbative QCD mechanisms. We subsequently investigate the competing effects of multiple b-pair production on measurements of CP-violation: i) the increase in event rate with multiple b-pair cross sections which may reac

K. Tanaka

We discuss the fermionic excitation spectra of the dense QCD and QED plasma at zero temperature, and analyze the stability of the normal (perturbative) ground state. The standard re-summed perturbation theory breaks down because the infrared (IR) divergences show up in the spectra near the Fermi surface. We employ the effective field theory approach and the

Naomichi Suzuki, Minoru Biyajima, Akinori Ohsawa

Pseudo-rapidity distributions of two high multiplicity events Ca-C and Si-AgBr observed by the JACEE are analysed by the wavelet transform. Wavelet spectra of those events are calculated and compared with the simulation calculations. The wavelet spectrum of Ca-C event somewhat resembles to that simulated with the uniform random numbers. That of Si-AgBr event

Thibault Damour, David Vokrouhlicky

The general form of the global conservation laws for $N$-body systems in the first post-Newtonian approximation of general relativity is considered. Our approach applies to the motion of an isolated system of $N$ arbitrarily composed and shaped, weakly self-gravitating, rotating, deformable bodies and uses a framework recently introduced by Damour, Soffel an

Anzhong Wang, Patricio S. Letelier

The stability of cosmological event and Cauchy horizons of spacetimes associated with plane symmetric domain walls are studied. It is found that both horizons are not stable against perturbations of null fluids and massless scalar fields; they are turned into curvature singularities. These singularities are light-like and strong in the sense that both the ti

G. Sardanashvily

One has not any conventional energy-momentum conservation law in Lagrangian field theory, but relations involving different stress-energy-momentum tensors associated with different connections. It is not obvious how to choose the true energy-momentum tensor. This problem is solved in the framework of the multimomentum Hamiltonian formalism which provides the

Joachim Schirmer

One can simplify the triad formulations of canonical gravity by abandoning any relation to a fixed coordinate system. That means in case of the \ADM formalism that one can determine the momentum by direct derivation of the Lagrange-3-form w.r.t the time-derivative of the triad-1-forms, thus the momentum is most naturally a 2-form. We apply this concept to th

S. Alexander Ridgway, Erick J. Weinberg

We construct static black hole solutions that have no rotational symmetry. These arise in theories, including the standard electroweak model, that include charged vector mesons with mass $m\ne 0$. In such theories, a magnetically charged Reissner-Nordstrom black hole with horizon radius less than a critical value of the order of $m^{-1}$ is classically unsta

K. D. Elworthy, Steven Rosenberg

We relate stability properties (i.e. moment exponents) of a stochastic dynamical system on a compact manifold $M$ to the homotopy and integral homology groups of $M$. In the special case of gradient Brownian systems associated to isometric immersions of $M$ in Euclidean space, these moment exponents can be estimated in terms of the second fundamental form of

F. Dominguez-Adame, A. Sanchez, Yu. S. Kivshar

We investigate propagation of a kink soliton along inhomogeneous chains with two different constituents, arranged either periodically, aperiodically, or randomly. For the discrete sine-Gordon equation and the Fibonacci and Thue-Morse chains taken as examples, we have found that the phenomenology of aperiodic systems is very peculiar: On the one hand, they ex

Caroline Lyon, Bob Dickerson

The pattern matching capabilities of neural networks can be used to locate syntactic constituents of natural language. This paper describes a fully automated hybrid system, using neural nets operating within a grammatic framework. It addresses the representation of language for connectionist processing, and describes methods of constraining the problem size.

Tomaz Prosen

The unitary representation of exact quantum Poincare mapping is constructed. It is equivalent to the compact representation in a sense that it yields equivalent quantization condition with important advantage over the compact version: since it preserves the probability it can be literally interpreted as the quantum Poincare mapping which generates quantum ti

C. Moss, M. Whittle, J. E. Pesce, H. Navarro

An objective prism H alpha survey has shown that there is a population of early type spiral galaxies in nearby clusters with strong central bursts of star formation which could be due to galaxy--galaxy tidal interactions. Such galaxies are rarely found in the field.

N. R. Tanvir, D. R. T. Robinson, T. von Hippel

Since the WFPC-2 undersamples the PSF, aperture photometry can produce results which are competetive with profile fitting in many situations. This article reports and investigation of aperture corrections using both real data and PSF models.

M. Pohl, W. Reich, T. P. Krichbaum, K. Standke

We report on multifrequency radio observations made with the Effelsberg 100-m telescope, the IRAM 30-m telescope and the Green Bank Interferometer between 1992 and 1994 of the $γ$-ray quasar 0528+134. We present a new VLBI based map of 0518+134 at 22 GHz with sub-mas angular resolution observed in November 1992, which shows a one-sided core jet structure of

Christian Gantz, Brian Steer

For an elliptic surface $q:Y \to Σ$, with prescribed singular fibres, Stefan Bauer proved directly via algebraic geometry that the stable bundles over $Y$, whose chern classes are pull backs from $Σ$, correspond to the stable (V-)bundles over $Σ$. We show, via a short proof in differential geometry, a generalisation to stable parabolic bundles. This uses ext

G. -M. Greuel, C. Hertling, G. Pfister

We construct coarse moduli spaces of semiquasihomogeneous hypersurface singularities with respect to right equivalence and contact equivalence. We have to fix the principal part of the semiquasihomogeneous singularities. For the moduli spaces with respect to contact equivalence we also fix the Hilbert function of the Tjurina algebra induced by the weights.

Pieter Nijsse

In this paper I consider a quintic surface in $\pp^3$, general in the sense of Noether-Lefschetz theory. The vector bundles of rank 2 on this surface which are $μ$-stable with respect to the hyperplane section and have $c_1 = K$, the canonical class of the surface and fixed $c_2$, are parametrized by a moduli space. This space is known to be irreducible for

V. A. Ilyin, A. E. Pukhov, V. I. Savrin, A. V. Semenov

In this paper we consider single leptoquark resonance production associated with the emission of a hard photon. We have obtained analytical formulae for differential and total cross sections for the cases of scalar and vector leptoquarks. We have found that in reactions with scalar leptoquarks there is no photon radiation in some directions depending on the

T. Banks

A formula is proposed which expresses free fermion fields in 2K dimensions in terms of the Cartan currents of the free fermion current algebra. This leads, in an obvious manner, to a vertex operator construction of nonabelian free fermion current algebras in arbitrary even dimension. It is conjectured that these ideas may generalize to a wide class of confor

Korkut Bardakci, Luis M. Bernardo

In the large N limit, conditions for the conformal invariance of the generalized Thirring model are derived, using two different approaches: the background field method and the Hamiltonian method based on an operator algebra, and the agreement between them is established. A free field representation of the relevant algebra is presented, and the structure of

Alok Kumar, Koushik Ray

We explicitly obtain the generalization of the Ehlers transformation for stationary axisymmetric Einstein equations to string theory. This is accomplished by finding the twist potential corresponding to the moduli fields in the effective two dimensional theory. Twist potential and symmetric moduli are shown to transform under an $O(d,d)$ which is a manifest

M. L. Nekrasov

An effective chiral lagrangian of order $p^2$, describing the interaction of light pseudoscalar (PS) mesons with $η'$-meson and PS-glueball, has been determined taking into consideration the renorm-group requirements imposed by QCD renormalization. It is shown that the interpolating fields for the lowest singlet quarkic and gluonic states, $η^0$ and $η^G

CHaranjit S. Aulakh

We show that self-dual Nielsen Olesen (NO) vortices in $3$ dimensions give rise to a class of exact solutions when coupled to Einstein Maxwell Dilaton gravity obeying the Majumdar-Papapetrou(MP) relation between gravitational and Maxwell couplings , provided certain Chern-Simons type interactions are present. The metric may be solved for explicitly in terms

L. Rozansky

We derive an analog of Melvin-Morton bound on the power series expansion of Jones polynomial of algebraically split links and boundary links. This allows us to produce a simple formula for the trivial connection contribution to Witten's invariant of rational homology spheres. We show that the n-th term in the 1/K expansion of the logarithm of this contri

Nobuharu Hayashi

We consider a special class of Kauffman's graph invariants of rigid vertex isotopy (graph invariants of Vassiliev type). They are given by a functor from a category of colored and oriented graphs embedded into a 3-space to a category of representations of the quasi-triangular ribbon Hopf algebra $U_q(sl(2,\bf C))$. Coefficients in expansions of them with

Frank D. Smith,

A generalized Feynman Checkerboard model is constructed using a 4-dimensional HyperDiamond lattice. The resulting phenomenological model is the D4-D5-E6 model described in hep-ph/9501252 and quant-ph/9503009.

Anu Venugopalan, R. Ghosh

The experiment of Etano et al which demonstrated the quantum Zeno effect (QZE) in an optical experiment was explained by Frerichs and Schenzle without invoking the wave function collapse. In this report it is proposed that the collapse does occur, and it can be explained by the `environment induced decoherence' theory. The environment here consists of th

Alexander Kirillov

Let $Φ:V\to V\otimes U$ be an intertwining operator between representations of a simple Lie algebra (quantum group, affine Lie algebra). We define its generalized character to be the following function on the Cartan subalgebra with values in $U$: $χ_Φ(h)=\Tr_V (Φe^h)$. These generalized characters are a rich source of special functions, possessing many inter

Mijo Batinic, Alfred Svarc

We show that the S-wave $ηN$ scattering length can be extracted in a model independent way within the scope of the multichannel model, but with the restricting assumption that only one resonance is included per partial wave. One has only to use the information on $πN$ elastic S-wave T-matrix at the $η$ production threshold, and near threshold $π^{-} p \right

E. Hernandez, E. Oset

We have used a conventional model for the $pp \rightarrow pp π^{0}$ reaction consisting of the Born term plus the $s$-wave rescattering term. As a novelty we have introduced the off shell dependence of the $πN$ $s$-wave isoscalar amplitude. This amplitude is appreciably enhanced when one moves to the off shell situations met in the problem and, as a conseque

Nikolaos A. Batakis

A new class of spatially homogeneous 4D string backgrounds, the $X(d\rightarrow)$ according to a recent classification, is presented and shown to contain only five generic types. In contrast to the case of $X(d\uparrow)$ (which contains as a subclass all possible FRW backgrounds), exact $SO(3)$ isotropy is always broken in the $X(d\rightarrow)$ class. This i

T. Gannon, P. Ruelle, M. Walton

We consider those two-dimensional rational conformal field theories (RCFTs) whose chiral algebras, when maximally extended, are isomorphic to the current algebra formed from some affine non-twisted Kac--Moody algebra at fixed level. In this case the partition function is specified by an automorphism of the fusion ring and corresponding symmetry of the Kac--P

Elisabeth Kraus, Klaus Sibold

Consequences of a symmetry, e.g.\ relations amongst Green functions, are renormalization scheme independently expressed in terms of a rigid Ward identity. The corresponding local version yields information on the respective current. In the case of spontaneous breakdown one has to define the theory via the BRS invariance and thus to construct rigid and curren

M. R. Niedermaier

A method to construct free field realizations for the form factors of diagonal factorized scattering theories is described. Form factors are constructed from linear functionals over an associative `form factor algebra', which in particular generate solutions of the deformed Knizhnik-Zamolodchikov equations with parameter $2π$. We show that there exists a

L. C. Biedenharn, L. P. Horwitz

The three-flavor Skyrme-'t Hooft-Witten model is interpreted in terms of a quark-like substructure, leading to a new model of explicitly confined color-free ``quarks'' reminiscent of Gell-Mann's original pre-color quarks, but with unexpected and significant differences.