December 1994 arXiv papers — page 11

Naoto Nagaosa, Masaki Oshikawa

Semiclassical approach has been developed for the one-dimensional interacting fermion systems. Starting from the incommensurate spin density wave (SDW) mean field state for the repulsive Hubbard model in 1D, the non-Abelian bosonized Lagrangian describing the spin-charge separation is obtained. The Berry phase term is derived from the chiral anomaly, and we

D. Bardin, M. Bilenky, A. Chizhov, O. Fedorenko

We describe how to use ZFITTER, a program based on a semi-analytical approach to fermion pair production in e+e- annihilation and Bhabha scattering. A flexible treatment of complete ${\cal O}(\alpha)$ QED corrections, also including higher orders, allows for three calculational {\bf chains} with different realistic sets of restrictions in the photon phase sp

T. Han, Z. Huang, P. Q. Hung

It is proposed that, in a strongly-interacting electroweak sector, besides the Goldstone bosons, the coexistence of a scalar state ($H$) and vector resonances such as $A_1$ [$I^G(J^P)=1^-(1^+$)], $V$ [$1^+(1^-)$] and $ω_H^{}$ [$0^-(1^-)$] is required by the proper Regge behavior of the forward scattering amplitudes. This is a consequence of the following wel

M. C. Cross, Yuhai Tu

A theory of the novel spiral chaos state recently observed in Rayleigh-Benard convection is proposed in terms of the importance of invasive defects i.e defects that through their intrinsic dynamics expand to take over the system. The motion of the spiral defects is shown to be dominated by wave vector frustration, rather than a rotational motion driven by a

Michael C. Birse

For a relativistic particle moving in the presence of mean scalar and vector fields, the energy at second order in the scalar field is shown to contain two contributions in general. One is a momentum-dependent repulsive interaction satisfying a low-energy theorem pointed out by Wallace, Gross and Tjon. The other does not vanish at zero-momentum and involves

Dmitri V. Alekseevsky, Peter W. Michor

For a more general notion of Cartan connection we define characteristic classes, we investigate their relation to usual characteristic classes.

W. Siegel

We reformulate self-dual supersymmetric theories directly in conformal chiral superspace, where superconformal invariance is manifest. The superspace can be interpreted as the generalization of the usual Atiyah-Drinfel'd-Hitchin-Manin twistors (the quaternionic projective line), the real projective light-cone in six dimensions, or harmonic superspace, bu

D. J. Lamb, A. Z. Capri

In this paper we calculate the massive particle creation as seen by a stationary observer in a $1+1$ dimensional spacetime compact in space. The Bogolubov transformation relating the annihilation and creation operators between two spacelike surfaces is calculated. The particle creation, as observed by a stationary observer who moves from the first spacelike

J. Fuchs, A. N. Schellekens, C. Schweigert

The recently introduced Galois symmetries of RCFT are generalized, for the WZW case, to `quasi-Galois symmetries'. These symmetries can be used to derive a large number of equalities and sum rules for entries of the modular matrix S, including some that previously had been observed empirically. In addition, quasi-Galois symmetries allow to construct modu

P. Holod, S. Pakuliak

A generalized AKNS systems introduced and discussed recently in \cite{dGHM} are considered. It was shown that the dressing technique both in matrix pseudo-differential operators and formal series with respect to the spectral parameter can be developed for these hierarchies.

R. Emparan

We present arguments pointing to a behavior of the string free energy in the presence of a black hole horizon similar to the Atick-Witten dependence on temperature beyond the Hagedorn transition. We give some evidence based on orbifold techniques applied to Rindler space and further support is found within a Hamiltonian approach. However, we argue that the i

B. Julia, H. Nicolai

The solutions of Einstein's equations admitting one non-null Killing vector field are best studied with the projection formalism of Geroch. When the Killing vector is lightlike, the projection onto the orbit space still exists and one expects a covariant theory with degenerate contravariant metric to appear, its geometry is presented here. Despite the co

V. A. Slobodenyuk

The upper bound for asymptotic behavior of the coefficients of expansion of the evolution operator kernel in powers of the time interval $\Dt$ was obtained. It is found that for the nonpolynomial potentials the coefficients may increase as $n!$. But increasing may be more slow if the contributions with opposite signs cancel each other. Particularly, it is no

R. B. Zhang

We present in detail the classification of the finite dimensional irreducible representations of the super Yangian associated with the Lie superalgebra $gl(1|1)$.

Eugene Tyurin

We have calculated the first-order beta-functions for a sigma-model ( with dilaton) dualized with respect to an arbitrary Lie group that acts without isotropy. We find that non-abelian duality preserves conformal invariance for semi-simple groups, but in general there is an extra contribution to the beta-function proportional to the trace of the structure co

Pran Nath, R. Arnowitt

A brief review is given of the decay b-s+gamma in SUSY extensions of the Standard Model.It is found that the recent CLEO results put strong constraints on the parameter space of the minimal N=1 Supergravity unified theory.Dark matter analyses are also strongly constrained for mu>0.

S. Moretti, W. J. Stirling

We calculate all the experimentally relevant branching ratios of the Higgs bosons of the Minimal Supersymmetric Standard Model, paying particular attention to the contributions from below--threshold decays. We show that in some cases these can significantly change the pattern of branching ratios calculated without taking off--shell effects into account

J. L. Goity, Marc Sher

The most general supersymmetric model contains baryon number violating terms of the form $λ_{ijk}\;\ov{D}_i\, \ov{D}_j\, \ov{U}_k$ in the superpotential. We reconsider the bounds on these couplings, assuming that lepton number conservation ensures proton stability. These operators can mediate $n - \ov{n}$ oscillations and double nucleon decay. We show that n

H. Neufeld

I discuss isospin breaking effects within the standard model. Chiral perturbation theory presents the appropriate theoretical framework for such an investigation in the low--energy range. Recent results on the electromagnetic contributions to the masses of the pseudoscalar mesons and the $K_{\ell 3}$ amplitudes are reported. Using the one--loop formulae for

Francesco Murgia, Maurizio Melis

We consider mass correction effects on the polar angular distribution of a baryon--antibaryon pair created in the chain decay process $e^-e^+ \to J/ψ\to B\bar B$, generalizing a previous analysis of Carimalo. We show the relevance of the features of the baryon distribution amplitudes and estimate the electromagnetic corrections to the QCD results.

Vadim Zeitlin

Low-temperature expansion of the effective Lagrangian of the QED$_{3+1}$ with a uniform magnetic field and a finite chemical potential is performed. Temperature corrections, as well as zero-temperature expression for the effective Lagrangian are presented as finite sums over partially filled Landau levels.

S. Y. Choi, K. Hagiwara, M. Tanabashi

We consider CP violating effects in the decays $τ\rightarrow (3π)ν_τ$ where both the ${\rm J}^{\rm P}=1^+$ resonance, $a_1$, and ${\rm J}^{\rm P}=0^-$ resonance, $π^\prime$, can contribute. The interference between the $a_1$ and $π^\prime$ resonances can lead to enhanced CP-violating asymmetries whose magnitudes depend crucially on the $π^\prime$ decay const

M. A. Braun

The Hartree-Fock approximation is applied to study the "high-colour pomerons" in the system of many reggeized gluons with a running QCD coupling constant. It is shown that, contrary to the fixed coupling case, the high-colour pomerons result supercritical, although with a smaller intercept than the multipomeron states.

G. T. Bodwin, S. Kim, D. K. Sinclair

We use the Bodwin-Braaten-Lepage factorization scheme to separate the long- and short-distance factors that contribute to the decay rates of $Υ$, $η_b$ (S-wave) and $χ_b$,$h_b$ (P-wave). The long distance matrix elements are calculated on the lattice in the quenched approximation using a non-relativistic formulation of the $b$ quark dynamics.

C. DeTar

I review recent progress in numerical simulations of finite temperature quantum chromodynamics and discuss the status of some outstanding problems. Included is (1) a discussion of recent results determining the temperature of the ``phase transition'' in full QCD, (2) a scaling analysis of the Polyakov loop variable, leading to the determination of a

Jeffrey E. Mandula, Michael C. Ogilvie

We discuss two related aspects of the lattice version of the heavy quark effective theory (HQET). They are the effects of heavy quark modes with large momenta, near the boundary of the Brillouin zone, and the renormalization of the lattice HQET. We argue that even though large momentum modes are present, their contributions to heavy-light bound states and pe

Mike Peardon

The two-flavour Schwinger model is used to test the local boson action algorithm of M Luescher. The autocorrelation time is found to rise linearly with the number of auxiliary boson fields. An extension to the algorithm is proposed which exactly reproduces the full dynamical partition function for any number of boson fields.

H. R. Rubinstein, S. Solomon, T. Wittlich

We compute the variation of the masses of the proton and the neutron induced by the presence of a strong external magnetic field. We discuss the choice of the wave function and different techniques how to apply the magnetic field. The results obtained from a 24 16^2 8 and a 16^2 8^2 lattice are compared with a phenomenological approach.

A. Hoferichter, V. K. Mitrjushkin, M. Müller-Preussker

The phase diagram for the compact lattice QED with Wilson fermions is shown. We discuss different methods for the calculation of the 'pion' mass $m_π$ near the chiral transition point $κ_c(β)$.

R. C. Brower, A. R. Levi, K. Orginos

In Hybrid Monte Carlo(HMC) simulations for full QCD, the gauge fields evolve smoothly as a function of Molecular Dynamics (MD) time. Thus we investigate improved methods of estimating the trial solutions to the Dirac propagator as superpositions of the solutions in the recent past. So far our best extrapolation method reduces the number of Conjugate Gradient

J. ~Engels, V. K. ~Mitrjushkin, T. ~Neuhaus

We derive an analytic expression for point-to-point correlation functions of the Polyakov loop based on the transfer matrix formalism. For the $2d$ Ising model we show that the results deduced from point-point spin correlators are coinciding with those from zero momentum correlators. We investigate the contributions from eigenvalues of the transfer matrix be

G. S. Bali, K. Schilling, A. Wachter

We present results on spin dependent potentials from lattice simulations of SU(2) gauge theory. The Coulomb like short range part of the central potential is identified as a mixed vector-scalar exchange while the linear long range part is pure scalar.

M. Baig

The main objective of the work presented here is to understand the appearance of phase transitions in pure gauge and scalar lattice QED. Main results are as follows: Pure gauge compact QED with PBC shows a monopole percolation phenomena coupled to the monopole condensation. Pure gauge compact QED with Fixed Boundary Conditions (spherical topology) shows a be

T. -C. Toh, M. R. Anderson

It has been conjectured by Rovelli that there is a correspondence between the space of link classes of a Riemannian 3-manifold and the space of 3-geometries (on the same manifold). An exact statement of his conjecture will be established and then verified for the case when the 3-manifold is compact, orientable and closed.

A. Corichi, M. Pierri

The behavior of a quantum test particle satisfying the Klein-Gordon equation in a certain class of 4 dimensional stationary space-times is examined. In a space-time of a spinning cosmic string, the wave function of a particle in a box is shown to acquire a geometric phase when the box is transported around a closed path surrounding the string. When interpret

A. A. Kirillov

The process of quantum creation of a qusihomogeneous inflationary universe near a cosmological singularity is considered. It is shown that during the evolution quantum fluctuations of spatial topologies increase and the universe acquires homogeneous and isotropic character on arbitrary large distances.

M. C. Bento, O. Bertolami

We consider the minisuperspace model arising from the lowest order string effective action containing the graviton and the dilaton and study solutions of the resulting Wheeler-Dewitt equation. The scale factor duality symmetry is discussed in the context of our quantum cosmological model.

M. Campanelli, C. O. Lousto, J. Audretsch

We consider perturbative solutions to the classical field equations coming from a quadratic gravitational lagrangian in four dimensions. We study the charged, spherically symmetric black hole and explicitly give corrections up to third order (in the coupling constant $β$ multiplying the $R_{μν}R^{μν}$ term) to the Reissner--Nordström hole metric. We consider

A. V. Karabegov

It is shown that the theory of spherical Harish-Chandra modules naturally provides the algebras of covariant, contravariant and mixed symbols on generalized flag manifolds. The general proof of the correspondence principle for all these symbol algebras is given.

S. Minton, J. Bresina, M. Drummond

For many years, the intuitions underlying partial-order planning were largely taken for granted. Only in the past few years has there been renewed interest in the fundamental principles underlying this paradigm. In this paper, we present a rigorous comparative analysis of partial-order and total-order planning by focusing on two specific planners that can be

W. L. Buntine

This paper is a multidisciplinary review of empirical, statistical learning from a graphical model perspective. Well-known examples of graphical models include Bayesian networks, directed graphs representing a Markov chain, and undirected networks representing a Markov field. These graphical models are extended to model data analysis and empirical learning u

S. Soderland, Lehnert. W

The vast amounts of on-line text now available have led to renewed interest in information extraction (IE) systems that analyze unrestricted text, producing a structured representation of selected information from the text. This paper presents a novel approach that uses machine learning to acquire knowledge for some of the higher level IE processing. Wrap-Up

Eunsik Kim, M. S. Makivik, D. L. Cox

We calculate non-linear Knight Shift $K$ vs. susceptibility $χ$ anomalies for Ce ions possessing local moments in metals. The ions are modeled with the Anderson Hamiltonian and studied within the non-crossing approximation (NCA). The $K-vs.- χ$ non-linearity diminishes with decreasing Kondo temperature $T_0$ and nuclear spin- local moment separation. Treatin

Vijay S. Pande, Alexander Yu. Grosberg, Toyoichi Tanaka

Mean field replica theory is employed to analyze the freezing transition of random heteropolymers comprised of an arbitrary number ($q$) of types of monomers. Our formalism assumes that interactions are short range and heterogeneity comes only from pairwise interactions, which are defined by an arbitrary $q \times q$ matrix. We show that, in general, there e

Giorgio Parisi Dipartimento di fisica Roma

In this talk I will review the approach to spin glasses based on the spontaneously broken replica symmetry. I will concentrate my attention mostly on more general ideas, skipping technical details and stressing the characteristic predictions of this approach. After the introduction of the replica method, the predicted structure of states is investigated in d

Sergio Albeverio, Roman Gielerak, Helge Holden, Torbjørn Kolsrud

We study low--temperature non Gaussian thermal fluctuations of a system of classical particles around a (hypothetical) crystalline ground state. These thermal fluctuations are described by the behaviour of a system of long range interacting charged dipoles at high--temperature and high--density. For the case of uniformly bounded fluctuations, the low--temper

Anton Kast

The fully-packed loop model of closed paths covering the honeycomb lattice is studied through its identification with the $sl_q(3)$ integrable lattice model. Some known results from the Bethe ansatz solution of this model are reviewed. The free energy, correlation length, and the ensemble average loop length are given explicitly for the many-loop phase. The

Bruce M. Boghosian, Washington Taylor

A method is described for calculating corrections to the Boltzmann/Chapman-Enskog analysis of lattice gases due to the buildup of correlations. It is shown that renormalized transport coefficients can be calculated perturbatively by summing terms in an infinite series. A diagrammatic notation for the terms in this series is given, in analogy with the Feynman

Bong Yeung Tom Lai, Changning Huang

Dependency Grammar has been used by linguists as the basis of the syntactic components of their grammar formalisms. It has also been used in natural language parsing. In China, attempts have been made to use this grammar formalism to parse Chinese sentences using corpus-based techniques. This paper reviews the properties of Dependency Grammar as embodied in

C. M. Bird, D. S. Davis, T. C. Beers

We have obtained a 12.5 ksec image of the Hercules Cluster, A2151, with the {\it ROSAT} PSPC. Comparison of the optical and X-ray data suggest the presence of at least three distinct subclusters in A2151. The brightest X-ray emission coincides with the highest-density peak in the galaxy distribution, and is bimodal. The northern subclump, distinct in positio

L. Maraschi, G. Fossati, G. Tagliaferri, A. Treves

We have observed with ROSAT six blazars from the sample of 31 polarized objects constructed by Impey and Tapia (1988). Results of the spectral analysis in the ROSAT band of three objects, PKS 0301-243, PKS 1055+018 and PG 1424+240 are presented here and compared with the three previously published objects. Using a simple power law model with free absorption

G. Vasisht, D. A. Frail, S. R. Kulkarni

We report the results of radio flux-monitoring and high resolution observations at 3.6 cm with the VLA, of the central condensation in G10.0-0.3, the radio nebula surrounding the soft gamma ray repeater (SGR) 1806-20. The quiescent X-ray source AX1805.7-2025 is coincident with the radio core suggesting that G10.0-0.3 is a plerionic supernova remnant. The mon

Gerard Gilmore, Rosemary F. G. Wyse, J. Bryn Jones

We present a determination of the thick disk iron abundance distribution obtained from an in situ sample of F/G stars. These stars are faint, $15 \simlt V \simlt 18$, selected on the basis of color, being a subset of the larger survey of Gilmore and Wyse designed to determine the properties of the stellar populations several kiloparsecs from the Sun. The fie