arXiv papers from February 1996

Francisco Gonzalez-Rey

We consider a theory with gauge group $G \times U(1)_A$ containing: i) an abelian factor for which the chiral matter content of the theory is anomalous $\sum_{f} q^f_A \neq 0 \neq \sum_{f} (q^f_A)^3$ ; ii) a nonanomalous factor $G$. In these models, the calculation of consistent gauge anomalies usually found in the literature as a solution to the Zumino-Stor

Jürgen Schulze

The Coulomb-gas description of minimal models is considered on the half plane. Screening prescriptions are developed by the perturbative expansion of the Liouville theory with imaginary coupling and with Neumann boundary condition on the bosonic field. To generate the conformal blocks of more general boundary conditions, we propose the insertion of boundary

Richard J. Micanek, James B. Hartle

Usual quantum mechanics predicts probabilities for the outcomes of measurements carried out at definite moments of time. However, realistic measurements do not take place in an instant, but are extended over a period of time. The assumption of instantaneous alternatives in usual quantum mechanics is an approximation whose validity can be investigated in the

Patrick Huet, Rajamani Narayanan, Herbert Neuberger

An overlap method for regularizing Majorana--Weyl fermions interacting with gauge fields is presented. A mod(2) index is introduced in relation to the anomalous violation of a discrete global chiral symmetry. Most of the paper is restricted to 2 dimensions but generalizations to 2+8k dimensions should be straightforward.

Alexey Bolsinov, Holger R. Dullin, Andreas Wittek

Two questions on the topology of compact energy surfaces of natural two degrees of freedom Hamiltonian systems in a magnetic field are discussed. We show that the topology of this 3-manifold (if it is not a unit tangent bundle) is uniquely determined by the Euler characteristic of the accessible region in configuration space. In this class of 3-manifolds for

B. B. Beard, U. -J. Wiese

Path integrals are usually formulated in discrete Euclidean time using the Trotter formula. We propose a new method to study discrete quantum systems, in which we work directly in the Euclidean time continuum. The method is of general interest and can be applied to studies of quantum spin systems, lattice fermions, and in principle also lattice gauge theorie

Ian. I. Kogan, C. Mudry, A. M. Tsvelik

It is established that the distribution of the zero energy eigenfunctions of (2 + 1)-dimensional Dirac electrons in a random gauge potential is described by the Liouville model. This model has a line of critical points parameterized by the strength of disorder and the scaling dimensions of the inverse participation ratios coincide with the dimensions obtaine

Stefan Mashkevich, Jan Myrheim, Kåre Olaussen

We use the method of solving the three-anyon problem developed in our earlier publication to evaluate numerically the third virial coefficient of free anyons. In order to improve precision, we explicitly correct for truncation effects. The present calculation is about three orders of magnitude more precise than the previous Monte Carlo calculation and indica

Lifan Wang, J. Craig Wheeler, Robert P. Kirshner, Peter M. Challis

We have used the Faint Object Spectrograph on the Hubble Space Telescope to observe the spectra of SN 1987A over the wavelength range 2000 -- 8000\ \AA\ on dates 1862 and 2210 days after the supernova outburst. Even these pre-COSTAR observations avoid much of the contamination from the bright stars nearby and provide a very useful set of line strengths and s

Lifan Wang, J. C. Wheeler

The conventional picture for the origin of the polarization of a supernova is based on a model of Thomson or resonance scattering of photons traveling through an aspherical supernova atmosphere. Positive detection of intrinsic polarization in SN 1987A is then interpretated as evidence of an asymmetrical supernova atmosphere. We show here a different view bas

Lifan Wang, J. Craig Wheeler, Zongwei Li, Alejandro Clocchiatti

We have made polarimetric observations of three Type Ia supernovae (SN Ia) and two type II supernovae (SN II). No significant polarization was detected for any of the SN Ia down to the level of 0.2\%, while polarization of order $1.0\%$ was detected for the two SN II 1994Y and 1995H. A catalog of all the SNe with polarization data is compiled that shows a di

Saurya Das, R. Parthasarathy

Planckian scattering of particles with angular momenta is studied by describing them as sources of Kerr metric. In the shock wave formalism, it is found that the angular momenta do not contribute to the scattering amplitude in the eikonal limit. This is confirmed by using the wave equation of the test particle in the Kerr background.

V. R. Gavrilov, V. D. Ivashchuk, V. N. Melnikov

The vacuum cosmological model on the manifold $R \times M_1 \times \ldots \times M_n$ describing the evolution of $n$ Einstein spaces of non-zero curvatures is considered. For $n = 2$ the Einstein equations are reduced to the Abel (ordinary differential) equation and solved, when $(N_1 = $dim $ M_1, N_2 = $ dim$ M_2) = (6,3), (5,5), (8,2)$. The Kasner-like b

Chi-Keung Chow

In the large $N_c$ limit, all hyperon decays involving the same quark diagram $Q\to Q'$ are described by a single weak form factor $\eta_{QQ'}(w)$. No assumption on the mass of $Q$ or $Q'$ is necessary, making our results applicable to both $b\to c$ and $c\to s$ transitions. This same form factor describes both $\Lambda_Q\to\Lambda_{Q'}$ and $\Sigma^{(*)}_Q\

S. Dittmaier, D. Schildknecht, G. Weiglein

From the LEP precision data and the measurement of the W-boson mass, upon excluding the observables Rb, Rc in a combined fit of the top-quark mass, Mt, and the Higgs-boson mass, MH, within the Standard Model, we find the weak 1sigma bound of MH<900GeV. Stronger upper bounds on MH, sometimes presented in the literature, rely heavily on the inclusion of Rb in

Yue Hu

We study the effective potential for composite operators. Introducing a source coupled to the composite operator, we define the effective potential by a Legendre transformation. We find that in three or fewer dimensions, one can use the conventionally defined renormalized operator to couple to the source. However, in four dimensions, the effective potential

Susumu Okubo, Noriaki Kamiya

Notions of quasi-classical Lie-super algebra as well as Lie-super triple systems have been given and studied with some examples. Its application to Yang-Baxter equation has also been given.

S. A. Frolov

The structure of the centres ${\cal Z}(\Lg)$ and ${\cal Z}(\Mg)$ of the graph algebra ${\cal L}_g(sl_2)$ and the moduli algebra ${\cal M}_g(sl_2)$ is studied at roots of 1. It it shown that ${\cal Z}(\Lg)$ can be endowed with the structure of the Poisson graph algebra. The elements of $Spec({\cal Z}(\Mg))$ are shown to satisfy the defining relation for the h

Mike Bisset, Sreerup Raychaudhuri, Probir Roy

At the LHC, directly pair-produced sleptons may be easier to identify than those arising in cascade decays of squarks or gluinos. Higgs exchange processes leading to such slepton pair-production are calculated to one-loop in the MSSM. It turns out, surprisingly, that their total contribution can dominate the usual Drell-Yan production in certain regions of t

Andrzej Baran, Krzysztof Pomorski, Michal Warda

Assuming a~simple spherical relativistic mean field model of the nucleus, we estimate the width of the antiproton--neutron annihilation ($\Gamma_n$) and the width of antiproton--proton ($\Gamma_p$) annihilation, in an antiprotonic atom system. This allows us to determine the halo factor $f$, which is then discussed in the context of experimental data obtaine

R. Fiore, L. L. Jenkovszky, F. Paccanoni

Recent experimental data on diffractive deep inelastic scattering collected by the H1 and ZEUS Collaborations at HERA are analysed in a model with a non-linear trajectory in the pomeron flux. The $t$ dependence of the diffractive structure function $F_2^{D(4)}$ is predicted. The normalization of the pomeron flux and the (weak) $Q^2$ dependence of the pomeron

M. Sander, C. Kuhrts, H. V. von Geramb

Characteristic properties of pionium $A_{2\pi}$ and associated low energy s--wave cross sections $\sigma(\pi^0\pi^0\to \pi^0\pi^0)$, $\sigma(\pi^+\pi^-\to\pi^0\pi^0)$ and $\sigma(\pi^0\pi^0\to \pi^+\pi^-)$ are investigated with a coupled channels potential model. Some experimental results and conclusions are to be reconsidered.

C. Adam

Within the Euclidean path integral and mass perturbation theory we derive, from the Dyson-Schwinger equations of the massive Schwinger model, a general formula that incorporates, for sufficiently small fermion mass, all the bound-state mass poles of the massive Schwinger model. As an illustration we perturbatively compute the masses of the three lowest bound

Lei-Han Tang

The equilibrium behavior of vortices in the classical two-dimensional (2D) XY model with uncorrelated random phase shifts is investigated. The model describes Josephson-Junction arrays with positional disorder, and has ramifications in a number of other bond-disordered 2D systems. The vortex Hamiltonian is that of a Coulomb gas in a background of quenched ra

G. Bonelli, M. Matone

We obtain the exact beta function for $N=2$ SUSY $SU(2)$ Yang-Mills theory and prove the nonperturbative Renormalization Group Equation $$ \partial_\Lambda{\cal F}(a,\Lambda)= {\Lambda\over \Lambda_0}\partial_{\Lambda_0}{\cal F}(a_0,\Lambda_0) e^{-2\int_{\tau_0}^\tau {dx \beta^{-1}(x)}}. $$

Y. S. Kim

It was shown by Gribov, Ioffe, Pomeranchuk in 1966 and by Ioffe in 1969 that a space-time picture is needed for the Lorentz deformation of hadronic interaction region. It is shown that this deformation is a squeeze transformation. It is shown also that Feynman's parton picture emerges as a consequence of Lorentz-squeezed hadrons in the quark model.

Jean-Claude Hausmann, Allen Knutson

We study the moduli spaces of polygons in R^2 and R^3, identifying them with subquotients of 2-Grassmannians using a symplectic version of the Gel'fand-MacPherson correspondence. We show that the bending flows defined by Kapovich-Millson arise as a reduction of the Gel'fand-Cetlin system on the Grassmannian, and with these determine the pentagon and hexagon

Marco Cavaglia`, Vittorio de Alfaro

We investigate a minisuperspace model of Einstein gravity plus dilaton that describes a static spherically symmetric configuration or a Kantowski - Sachs like universe. We develop the canonical formalism and identify canonical quantities that generate rigid symmetries of the Hamiltonian. Quantization is performed by the Dirac and the reduced methods. Both ap

A. Gabutti, M. Olechowski, S. Cooper, S. Pokorski

The allowed parameter space for the lightest neutralino as the dark matter is explored using the Minimal Supersymmetric Standard Model as the low-energy effective theory without further theoretical constraints such as GUT. Selecting values of the parameters which are in agreement with present experimental limits and applying the additional requirement that t

Francesc M. Borzumati, N. Polonsky

We analyze the two decays $\thb$, $\tstn$ within the Minimal Supersymmetric Standard Model with radiative breaking of the electroweak sector. We discuss their detectability at present and in the eventuality that supersymmetry is not discovered at LEPII.

Dimitris Kugiumtzis

The most common state space reconstruction method in the analysis of chaotic time series is the Method of Delays (MOD). Many techniques have been suggested to estimate the parameters of MOD, i.e. the time delay $\tau$ and the embedding dimension $m$. We discuss the applicability of these techniques with a critical view as to their validity, and point out the

H. Heiselberg

The effects of resonances and flow on the correlation function for two identical particles are described assuming chaotic sources and classical propagation of particles. Expanding to second order in relative momenta, the source sizes can be calculated directly and understood as contributions from various fluctuations in the source. Specific calculations of s

Alberto Saa

In this work we study the asymptotically flat, static, and spherically symmetric black-hole solutions of the theory described by the action $$S = \int d^nx\sqrt{-g} \left\{\left(1-\xi\phi^2 \right)R - g^{\mu\nu}\partial_\mu\phi\partial_\nu\phi\right\},$$ with $n>3$ and arbitrary $\xi$. We demonstrate the absence of scalar hairs for $\xi<0$. For $\xi>\xi_c=\f

Gianfranco Casnati, Fabrizio Catanese

Let k be an algebraically closed field of characteristic p different from 2, and let F be a nodal surface of degree d in the projective 3-space P over k (i.e. the singularities of F are only ordinary quadratic, nodes for short). Let N be a subset of the set of nodes of F: then N is said to be n/2-even for n=0,1 if the following condition (*) holds. Namely, l

L. Dcabrowski, P. M. Hajac, G. Landi, P. Siniscalco

Properties of metrics and pairs consisting of left and right connections are studied on the bimodules of differential 1-forms. Those bimodules are obtained from the derivation based calculus of an algebra of matrix valued functions, and an $SL\sb q(2,\IC)$-covariant calculus of the quantum plane plane at a generic $q$ and the cubic root of unity. It is shown

Urs Buergi

We evaluate the amplitude for gamma gamma --> pi^+ pi^- to two loops in the framework of chiral perturbation theory.The three new coupling constants that enter the result at this order in the low-energy expansion are estimated via resonance saturation. We discuss in addition the crossed channel processes gamma pi^+ --> gamma pi^+ - in particular the charged

Rohini M. Godbole

After briefly explaining the idea of photon structure functions (\f2gam\ , \flgam) I review the current theoretical and experimental developements in the subject of extraction of \qvph\ from a study of the Deep Inelastic Scattering (DIS). I then end by pointing out recent progress in getting information about the parton content of the photon from hard proces

P. Marcel, V. Ovsienko, C. Roger

We consider the universal central extension of the Lie algebra $\Vect (S^1)${\math \s}$ C^{\infty}(S^1)$. The coadjoint representation of this Lie algebra has a natural geometric interpretation by matrix analogues of the Sturm-Liouville operators. This approach leads to new Lie superalgebras generalizing the well-known Neveu-Schwartz algebra.

A. Ekert, C. Macchiavello

We show how procedures which can correct phase and amplitude errors can be directly applied to correct errors due to quantum entanglement. We specify general criteria for quantum error correction, introduce quantum versions of the Hamming and the Gilbert-Varshamov bounds and comment on the practical implementation of quantum codes.

Ivan G. Avramidi

We study the low-energy approximation for calculation of the heat kernel which is determined by the strong slowly varying background fields in strongly curved quasi-homogeneous manifolds. A new covariant algebraic approach, based on taking into account a finite number of low-order covariant derivatives of the background fields and neglecting all covariant de

P. Zupanovic, A. Bjelis, S. Barisic

Starting from the tight-binding dielectric matrix in the random phase approximation we examine the collective modes and electron-hole excitations in a two-band electronic system. For long wavelengths (${\bf q}\rightarrow0$), for which most of the analysis is carried out, the properties of the collective modes are closely related to the symmetry of the atomic

O. P. Sushkov

Basing on t-J model we calculate the k-dependence of a single hole photoproduction probability for CuO2 plane at zero doping. We also discuss the radiation of spin-waves which can substantially deform the shape of photoemission spectra.

F. M. C. Witte

In this brief report we adress spontaneous symmetry breaking in a finite-temperature scalar meson plasma. We calculate the in-medium averaged thermal $\sigma-\sigma$ scattering crossection and the related shear viscosity $\eta(T)$ and mean-free-path $L(T)$. Our results suggest that slightly below the critical temperature there is a 30 percent peak in the cro

Frank Cuypers

We consider indirect searches for additional neutral vector bosons in $e^+e^-$ and $e^-e^-$ collisions, and compare these two linear collider modes with similar analysis procedures and assumptions. Discovery limits and resolving power are discussed in a model independent way.

Grigirii Pivovarov

We derive a relation between four-fermion QED Green functions of different covariant gauges which defines the gauge dependence completely. We use the derived gauge dependence to check the gauge invariance of atom-like bound state calculations. We find that the existing QED procedure does not provide gauge invariant binding energies. A way to a corrected gaug

V. N. Muthukumar, Roser Valenti, Claudius Gros

A microscopic model of non-reciprocal optical effects in antiferromagnets is developed by considering the case of Cr_2O_3 where such effects have been observed. These effects are due to a direct coupling between light and the antiferromagnetic order parameter. This coupling is mediated by the spin-orbit interaction and involves an interplay between the break

P. Torma, S. Stenholm

We propose a realization of quantum computing using polarized photons. The information is coded in two polarization directions of the photons and two-qubit operations are done using conditional Faraday effect. We investigate the performance of the system as a computing device.

Ferenc Pazmandi, Gergely T. Zimanyi, Richard T. Scalettar

We develop a theory for the quantum vortex glass, with both the coupling strengths and the site energies disordered. This model is closely related to XY spin glasses and bosons in random media. For properly chosen distributions of the site disorder the phase diagram consists of a superfluid phase, and Weak and Strong Glass regions, dominated by long range an

S. Das Sarma, E. H. Hwang

We provide a self-contained theoretical analysis of the dynamical response of a one dimensional electron system, as confined in a semiconductor quantum wire, within the random phase approximation. We carry out a detailed comparison with the corresponding two and three dimensional situations, and discuss the peculiarities arising in the one dimensional linear

Vladan Lucic

The leading correction to the smoothed connected energy density-density correlation function is obtained for the large energy difference, within the context of the Gaussian Random Matrix Theory. In order to achieve this result, the supersymmetry method is extended beyond the sigma-model, to include small quadratic fluctuations around the saddle point. Specia

Mirjam Cvetic, Paul Langacker

We address the mass ranges of new neutral gauge bosons and constraints on the accompanying exotic particles as predicted by a class of superstring models. Under certain assumptions about the supersymmetry breaking parameters we show that breaking of an additional U(1)' symmetry is radiative when the appropriate Yukawa couplings of exotic particles are of ord

B. M. Pimentel, J. L. Tomazelli

We evaluate the Wilson loop at second order in general non-covariant gauges by means of the causal principal-value prescription for the gauge- dependent poles in the gauge-boson propagator and show that the result agrees with the usual causal prescriptions.

Kingman Cheung, Wai-Yee Keung, Tzu Chiang Yuan

The direct production rate of $\psi$ in the $\Upsilon$ decay is shown to be dominated by the process $ \Upsilon \to ggg^*$ followed by $g^* \to \psi$ via the color-octet mechanism proposed recently to explain the anomalous prompt charmonium production at the Tevatron. We show that this plausibly dominant process has a branching ratio compatible with the expe

Isaac Shlosman

We investigate gas dynamics in the presence of a double inner Lindblad resonance within a barred disk galaxy. Using an example of a prominent spiral, M100, we reproduce the basic central morphology, including four dominant regions of star formation corresponding to the compression maxima in the gas. These active star forming sites delineate an inner boundary

Vicente Cortés

Motivated by the physical concept of special geometry two mathematical constructions are studied, which relate real hypersurfaces to tube domains and complex Lagrangean cones respectively. Me\-thods are developed for the classification of homogeneous Riemannian hypersurfaces and for the classification of linear transitive reductive algebraic group actions on

Fouad Chaatit

We show that any separable stable Banach space can be represented as a group of isometries on a separable reflexive Banach space, which extends a result of S. Guerre and M. Levy. As a consequence, we can then represent homeomorphically its space of types.

Piet Hut

Three important developments are vastly increasing our understanding of the role of binaries in the dynamical evolution of globular clusters. From the observational side, the Hubble Space Telescope has shown us detailed pictures of the densest areas in post-collapse cluster cores. From the computational side, the Grape-4 special-purpose hardware is now allow

Valerio Faraoni

It is shown that the amplification of a light beam by gravitational waves in scalar-tensor theories of gravity is a first order effect in the wave amplitudes. In general relativity, instead, the effect is only of second order.

D. Friedli

The dynamical stability and evolution of disc galaxies with different disc thickness as well as various fraction and concentration of stellar counter-rotation is investigated with self-consistent numerical simulations. In particular, systems of nested, counter-rotating, stable bars are presented. As for the direct case, the nuclear secondary bar rotates fast

G. De Zotti, P. Mazzei, A. Franceschini, L. Danese

Several lines of evidence and theoretical arguments suggest that a large fraction of starlight is absorbed by interstellar dust and re-radiated at far-IR wavelengths, particularly during early evolutionary phases of early type galaxies, which may even, under some circumstances, experience an optically thick phase. Therefore far-IR to mm observations are cruc

A. J. Millis, R. Mueller, Boris I. Shraiman

We use the dynamical mean field method to study a model of electrons Jahn-Teller coupled to localized classical oscillators and ferromagnetically coupled to ``core spins'', which, we argue, contains the essential physics of the ``colossal magnetoresistance'' manganites $Re_{1-x} A_x MnO_3$. We determine the different regimes of the model and present results

Neta A. Bahcall, Siang Peng Oh

The peculiar velocity function of clusters of galaxies is determined using an accurate sample of cluster velocities based on Tully-Fisher distances of Sc galaxies (Giovanelli et al 1995b). In contrast with previous results based on samples with considerably larger velocity uncertainties, the observed velocity function does not exhibit a tail of high velocity

A. J. Millis, R. Mueller, Boris I. Shraiman

We use analytic techniques and the dynamical mean field method to study the crossover from fermi liquid to polaron behavior in models of electrons interacting with dispersionless classical phonons.

Beatriz Gato-Rivera, Jose Ignacio Rosado

We show that the N=2 determinant formulae of the Aperiodic NS algebra and the Periodic R algebra can be applied directly to incomplete Verma modules built on chiral primary states and on Ramond ground states, respectively, provided one modifies the interpretation of the zeroes in an appropriate way. That is, the zeroes of the determinat formulae account for

T. T. Chou, Chen Ning Yang, L. H. Yu

We point out that the local density approximation (LDA) of Oliva is an adaptation of the Thomas-Fermi method, and is a good approximation when $\varepsilon = \hbar\omega/kT <<1$. For the case of scattering length $a > 0$, the LDA leads to a quantitative result (14') easily checked by experiments. Critical remarks are made about the physics of the many body p

Rodolfo Gambini, Jorge Pullin

The expectation value of a Wilson loop in a Chern--Simons theory is a knot invariant. Its skein relations have been derived in a variety of ways, including variational methods in which small deformations of the loop are made and the changes evaluated. The latter method only allowed to obtain approximate expressions for the skein relations. We present a gener

Mitchell Rothstein

The Fourier-Mukai transform is lifted to the derived category of sheaves with connection on abelian varieties. The case of flat connections (D-modules) is discussed in detail.

Marc Kamionkowski

In an intriguing recent paper, Crittenden and Turok proposed cross-correlating the cosmic microwave background (CMB) with tracers of the matter density to probe the existence of a cosmological constant. Here I emphasize that a similar cross-correlation arises in an open Universe and, depending on the redshift distribution of the tracer population and the mat

Kimyeong Lee, Erick J. Weinberg, Piljin Yi

We study the moduli space for an arbitrary number of BPS monopoles in a gauge theory with an arbitrary gauge group that is maximally broken to $U(1)^k$. From the low energy dynamics of well-separated dyons we infer the asymptotic form of the metric for the moduli space. For a pair of distinct fundamental monopoles, the space thus obtained is $R^3 \times(R^1\

Adam D. Helfer

We compute the stress--energy operator for a scalar linear quantum field in curved space-time, modulo c-numbers. For the associated Hamiltonian operators, even those generating evolution along timelike vector fields, we find that in general on locally Fock-like (`Hadamard') representations: (a) The Hamiltonians cannot be self-adjoint operators; (b) The autom

M. Baker, J. S. Ball, N. Brambilla, G. M. Prosperi

In this paper we express the velocity dependent, spin dependent heavy quark potential $V_{q\bar q}$ in QCD in terms of a Wilson Loop $W(\Gamma)$ determined by pure Yang Mills theory. We use an effective dual theory of long-distance Yang Mills theory to calculate $W(\Gamma)$ for large loops; i.e. for loops of size $R > R_{FT}$. ($R_{FT}$ is the flux tube radi

X. Song, P. K. Kabir, J. S. McCarthy

It is shown that hyperon beta decay data can be well accommodated within the framework of Cabbibo's SU(3) symmetric description if one allows for a small SU(3) symmetry breaking proportional to the mass difference between strange and nonstrange quarks. The F/D ratio does not depend sensitively on the exact form of the symmetry-breaking, and the best fits are

Jysoo Lee, Joel Koplik

We present a simple model for deep bed filtration, where particles suspended in a fluid are trapped while passing through a porous filter. A steady state of the model is reached when filter can not trap additional particles. We find the model has two qualitatively different steady states depending on the fraction of traps, and the steady states can be descri

P. Zupanovic, A. Bjelis, S. Barisic

The screened electron-electron interaction in a multi-band electron system is calculated within the random phase approximation and in the tight-binding representation. The obtained dielectric matrix contains, beside the usual site-site correlations, also the site-bond and bond-bond correlations, and thus includes all physically relevant polarization processe

Norbert Dragon

The BRS symmetry determines physical states, Lagrange densities and candidate anomalies. It renders gauge fixing unobservable in physical states and is required if negative norm states are to decouple also in interacting models. The relevant mathematical structures and the elementary cohomological investigations are presented.

C. E. M. Batista, J. C. Fabris

We consider an inflationary model inspired in the low energy limit of string theory. In this model, the scale factor grows exponentially with time. A perturbation study is performed, and we show that there is a mode which displays an exponential growth in the perturbation of the scalar field.

C. Klimcik, P. Severa

The account of the Poisson-Lie T-duality is presented for the case when the action of the duality group on a target is not free. At the same time a generalization of the picture is given when the duality group does not even act on $\si$-model targets but only on their phase spaces. The outcome is a huge class of dualizable targets generically having no local

Jouko Mickelsson

A calculation of the chiral anomaly on a finite lattice without fermion doubling is presented . The lattice gauge field is defined in the spirit of noncommutative geometry. Standard formulas for the continuum anomaly are obtained as a limit.

Matthias Heyssler

We give predictions for diffractive heavy flavour production at the Tevatron and the LHC in leading--order approximation. In the framework of these studies we use three different models for the partonic structure of the Pomeron recently proposed by Stirling and Kunszt. These Pomeron models are, despite being fitted to the same diffractive deep inelastic HERA

Urs Buergi

We evaluate the electric and magnetic polarizabilities of charged pions in the framework of chiral perturbation theory at next-to-leading order. This requires a two-loop evaluation of the Compton amplitude near threshold. We estimate the two new low-energy constants which enter the chiral expansion at this order with resonance saturation. The numerical resul

T. Kleinwort, G. Kramer

We have calculated inclusive one-- and two--jet production in photon--photon collisions superimposing direct, single resolved and double resolved cross sections for center of mass energies of the LEP1, LEP2 and NLC range. The direct and single resolved cross sections are calculated up to next--to--leading order. The double resolved two--jet cross section is

L. S. Garcia-Colin, V. Micenmacher

The main objective of this paper is to show that, within the present framework of the kinetic theoretical approach to irreversible thermodynamics, there is no evidence that provides a basis to modify the ordinary Fourier equation relating the heat flux in a non-equilibrium steady state to the gradient of the local equilibrium temperature. This fact is suppor

S. V. Zuev

6 pages, LaTeX, to appear in Proc. of International Conf. "Geometrization of Physics - II", Kazan, Russia, Oct 28 - Nov 2, 1995. Withdrawn

M. Rainer

Among plenty of applications, low-dimensional homogeneous spaces appear in cosmological models as both, classical factor spaces of multidimensional geometry and minisuperspaces in canonical quantization. Here a new tool to restrict their continuous deformations is presented: Classifying spaces for homogeneous manifolds and their related Lie isometry deformat

S. Laporta, E. Remiddi

We have evaluated in closed analytical form the contribution of the three-loop non-planar `triple-cross' diagrams contributing to the electron (g-2) in QED; its value, omitting the already known infrared divergent part, is a_e(3-cross) = 1/2 pi^2 Z(3) - 55/12 Z(5) - 16/135 pi^4 + 32/3 (a4 + 1/24 ln(2)^4) + 14/9 pi^2 ln(2)^2 - 1/3 Z(3) + 23/3 pi^2 ln(2) - 47/

ZEUS Collaboration

Diffractive scattering of $\gamma^* p \to X + N$, where $N$ is either a proton or a nucleonic system with $M_N~<~4$~GeV has been measured in deep inelastic scattering (DIS) at HERA. The cross section was determined by a novel method as a function of the $\gamma^* p$ c.m. energy $W$ between 60 and 245~GeV and of the mass $M_X$ of the system $X$ up to 15~GeV a

J. E. Paschalis, P. I. Porfyriadis

The four dimensional SU(2) WZW model coupled to elecromagnetism is treated as a constraint system in the context of the BFV approach. We show that the Darboux's transformations which are used to diagonalize the canonical one-form in the Faddeev-Jackiw formalism, transform the fields of the model into BRST invariant ones. The same analysis is also carried out

L. L. Bonilla, F. G. Padilla, G. Parisi, F. Ritort

We study the analytical solution of the Monte Carlo dynamics in the spherical Sherrington-Kirkpatrick model using the technique of the generating function. Explicit solutions for one-time observables (like the energy) and two-time observables (like the correlation and response function) are obtained. We show that the crucial quantity which governs the dynami

F. Bonetto, G. Gallavotti

We describe a way of interpreting the chaotic principle of (ref. [GC1]) more extensively than it was meant in the original works. Mathematically the analysis is based on the dynamical notions of Axiom A and Axiom B and on the notion of Axiom C, that we introduce arguing that it is suggested by the results of an experiment (ref. [BGG]) on chaotic motions. Phy

Colin A. Norman, Andrea Ferrara

We discuss the likely sources of turbulence in the ISM and explicitly calculate the detailed grand source function for the conventional sources of turbulence from supernovae, superbubbles, stellar winds and HII regions. We find that the turbulent pumping due to the grand source function is broad band, consequently expanding the inertial range of the cascade.

Yuri B. Suris

We demonstrate that in a certain gauge the Lax matrices of the rational and hyperbolic Ruijsenaars--Schneider models have a quadratic $r$-matrix Poisson bracket which is an exact quadratization of the linear $r$--matrix Poisson bracket of the Calogero--Moser models. This phenomenon is explained by a geometric derivation of Lax equations for arbitrary flows o

B. A. Arbuzov

Triple gauge boson vertex, which is inherent to the model of a dynamical breaking of the electroweak symmetry, leads to an effective four-fermion interaction of quarks. Calculation of the effective coupling constant in the framework of the model results in agreement with recent information on enhancement of inclusive high E_T jet cross section at \sqrt{s} =

C. Frønsdal

This paper continues our investigation of a class of generalized quantum groups. The "standard" R-matrix was shown to be the unique solution of a very simple, linear recursion relation and the classical limit was obtained in the case of quantized Kac-Moody algebras of finite type. Here the standard R-matrix for generalized quantum groups is first examined in

V. Karimipour

We show that the integrability of the dynamical system recently proposed by Calogero and characterized by the Hamiltonian $ H = \sum_{j,k}^{N} p_j p_k \{\lambda + \mu cos [ \nu ( q_j - q_k)] \} $ is due to a simple algebraic structure . It is shown that the integrals of motion are related to the Casimiar invariants of of the $su(1,1)$ algebra. Our method sho

Avraham E. Mayo, Jacob D. Bekenstein

We prove three theorems in general relativity which rule out classical scalar hair of static, spherically symmetric, possibly electrically charged black holes. We first generalize Bekenstein's no--hair theorem for a multiplet of minimally coupled real scalar fields with not necessarily quadratic action to the case of a charged black hole. We then use a confo

M. Goeckeler, R. Horsley, E. -M. Ilgenfritz, H. Perlt

For lattice operators that are relevant to the calculation of moments of nucleon structure functions we investigate the transformation properties under the hypercubic group. We give explicit bases of irreducible subspaces for tensors of rank up to 4.

Chang-Yeong Lee

Noncommutative geometric gauge theory is reconstructed based on the superconnection concept. The bosonic action of the Connes-Lott model including the symmetry breaking Higgs sector is obtained by using a new generalized derivative, which consists of the usual 1-form exterior derivative plus an extra element called the matrix derivative, for the curvatures.

Jae Sik Lee, Jae Kwan Kim

We study the effects of the one-loop matching conditions on Higgs boson and top quark masses on the triviality bounds on the Higgs boson mass using $\beta_{\lambda}$ with corrected two-loop coefficients. We obtain quite higher results than previous ones and observe that the triviality bounds are not nearly influenced by varying top quark mass over the range

D. E. Evans, A. Kishimoto

Trace scaling automorphisms of stable AF algebras with dimension group totally ordered are outer conjugate if the scaling factors are the same (not equal to one). This is an adaptation of a similar result for the AFD type II_infty factor by Connes and extends the previous result for stable UHF algebras.

Chikashi Miyazaki, Wolfgang Vogel

The aim of this paper is to start a systematic investigation of the arithmetic degree of projective schemes as introduced by D. Bayer and D. Mumford. One main theme concerns itself with the behaviour of this arithmetic degree under hypersurface sections. The notion of arithmetic degree involves the new concept of length-multiplicity of embedded primary ideal