May 1994 arXiv papers — page 7

Ferruccio Feruglio

We review the aspects of chiral gauge theories related to the violation of the decoupling property. The case of the top quark is worked out in detail. The mechanism of anomaly cancellation in the low-energy effective theory is illustrated in a simple model.

Gerhard Buchalla, Andrzej J. Buras

We point out that the measurement of just the two branching fractions \linebreak $B(K^+\toπ^+ν\barν)$ and $B(K_L\toπ^0ν\barν)$ can in a theoretically clean manner determine $\sin 2β$ almost independently of $m_t$ and $V_{cb}$. This allows to obtain an interesting relation between the CP asymmetry $A_{CP}(ψK_S)$ in B physics and the branching ratios for these

J. McCurry

Single sparticle creation in high energy collisions as a consequence explicit $R$-parity breaking, could be a rich source of highly spectacular signals at future colliders. One particular process, which could lead to a highly exotic leptonic signal at the LHC, is monoslepton production. In this paper we qualitatively discuss the constraints on the signal for

B. L. Cerchiai, M. Martellini, F. Valz-Gris

In this paper we show that the Boltzmann weights of the three-dimensional Baxter-Bazhanov model give representations of the braid group, if some suitable spectral limits are taken. In the trigonometric case we classify all possible spectral limits which produce braid group representations. Furthermore we prove that for some of them we get cyclotomic invarian

Guillermo A Mena Marugan

We carry out to completion the quantization of a Friedmann-Robertson-Walker model provided with a conformal scalar field, and of a Kantowski-Sachs spacetime minimally coupled to a massless scalar field. We prove that the Hilbert space determined by the reality conditions that correspond to Lorentzian gravity admits a basis of wormhole wave functions. This re

Jose P. Mimoso, David Wands

We derive exact Friedmann--Robertson--Walker cosmological solutions in general scalar--tensor gravity theories, including Brans--Dicke gravity, for stiff matter or radiation. These correspond to the long or short wavelength modes respectively of massless scalar fields. If present, the long wavelength modes of such fields would be expected to dominate the ene

R. Fehrenbacher, M. R. Norman

The effects of non-magnetic impurities on the properties of superconductors with order parameters (OP) of different symmetry are discussed. In particular, we contrast the case of a d_{x^2 - y^2} with various forms of an anisotropic s-wave (ASW) gap. The biggest qualitative difference occurs if the phase of the s-wave OP does not change sign.

Daniel ben-Avraham, Francois Leyvraz, Sid Redner

We investigate the temporal evolution and spatial propagation of branching annihilating random walks in one dimension. Depending on the branching and annihilation rates, a few-particle initial state can evolve to a propagating finite density wave, or extinction may occur, in which the number of particles vanishes in the long-time limit. The number parity con

Yasuhiro Hatsugai, Mahito Kohmoto, Yong-Shi Wu

For Bloch electrons in a magnetic field, explicit solutions are obtained at the center of the spectrum for the Bethe ansatz equations recently proposed by Wiegmann and Zabrodin. When the magnetic flux per plaquette is $1/Q$ where $Q$ is an odd integer, distribution of the roots is uniform on the unit circle in the complex plane. For the semi-classical limit,

T. Ivanov, V. Valtchinov

We calculate the I-V characteristics of a tunnel junction containing impurities in the barrier. We consider the indirect resonant tunneling involving the impurities. The Coulomb repulsion energy $E_c$ between two electrons with opposite spins simultaneously residing on the impurity is introduced by an Anderson Hamiltonian. At low temperatures $T \ll E_c$ the

Andreas Stolcke, Stephen M. Omohundro

This report describes a new technique for inducing the structure of Hidden Markov Models from data which is based on the general `model merging' strategy (Omohundro 1992). The process begins with a maximum likelihood HMM that directly encodes the training data. Successively more general models are produced by merging HMM states. A Bayesian posterior prob

Harel Primack, Uzy Smilansky

Non-generic contributions to the quantal level-density from parallel segments in billiards are investigated. These contributions are due to the existence of marginally stable families of periodic orbits, which are structurally unstable, in the sense that small perturbations, such as a slight tilt of one of the segments, destroy them completely. We investigat

Ted Pyne, Mark Birkinshaw

We obtain analytic formulae for the null geodesics of Friedmann-Lema\^ıtre-Robertson-Walker spacetimes with scalar perturbations in the longitudinal gauge. We use these to provide a rigorous derivation of the cosmological lens equation. We obtain an expression for the magnification of a bundle of light rays in these spacetimes without restriction to static o

A. P. Szabo, R. J. Protheroe

We consider the production of high energy neutrinos and cosmic rays in radio-quiet active galactic nuclei (AGN) or in the central regions of radio-loud AGN. We use a model in which acceleration of protons takes place at a shock in an accretion flow onto a supermassive black hole, and follow the cascade that results from interactions of the accelerated proton

Michael Thaddeus

We study the dependence of geometric invariant theory quotients on the choice of a linearization. We show that, in good cases, two such quotients are related by a flip in the sense of Mori, and explain the relationship with the minimal model programme. Moreover, we express the flip as the blow-up and blow-down of specific ideal sheaves, leading, under certai

H. Park, C. Woodburn

Let $k$ be a field. Then Gaussian elimination over $k$ and the Euclidean division algorithm for the univariate polynomial ring $k[x]$ allow us to write any matrix in $SL_n(k)$ or $SL_n(k[x])$, $n\geq 2$, as a product of elementary matrices. Suslin's stability theorem states that the same is true for the multivariate polynomial ring $SL_n(k[x_1,\ldots ,x_

Bernardo A. Huberman, Natalie S. Glance

Individuals in groups must often choose between acting selfishly and cooperating for the common good. The choices they make are based on their beliefs on how they expect their actions to affect others. We show that for a broad set of beliefs and group characteristics cooperation can appear spontaneously in non-cooperative groups after very long periods of ti

Dimitra Karabali

We show that a large class of incompressible quantum Hall states correspond to different representations of the \Winf algebra by explicit construction of the second quantized generators of the algebra in terms of fermion and vortex operators. These are parametrized by a set of integers which are related to the filling fraction. The class of states we conside

B. Alles

A semi-analytic method to compute the first coefficients of the renormalization group functions on a random lattice is introduced. It is used to show that the two-dimensional $O(N)$ non-linear $σ$-model regularized on a random lattice has the correct continuum limit. A degree $κ$ of ``randomness'' in the lattice is introduced and an estimate of the r

J. D. Brown, J. W. York

The first objective of this article is to show that the black hole partition function can be placed on a firm logical foundation by enclosing the black hole in a spatially finite "box" or boundary. The presence of the box has the effect of stabilizing the black hole and yields a system with a positive heat capacity. The second objective of this artic

Wei Chen

We introduce Chern-Simons interaction into the three dimensional four-fermi theory, ad suggest a possible line of non-Gaussian infrared stable fixed points of the four-fermi operator, this line is characterized by the Chern-Simons coupling.

Ronald Fintushel, Ronald Stern

In this paper we present a formula which relates the Donaldson invariants of a 4-manifold X with the Donaldson invariants of its blowup X#-CP(2). This blow-up formula is independent of X and involves sigma-functions associated to a naturally arising elliptic function. This, the final version, corrects some earlier misconceptions regarding signs.

V. Castellani, S. Degl'Innocenti, G. Fiorentini, B. Ricci

Recent solar neutrino results together with the assumption of a stationary Sun imply severe constraints on the individual components of the total neutrino flux : $Φ_{Be} \leq 0.7 \cdot 10^{9} cm^{-2} s^{-1}, Φ_{CNO} \leq 0.6 \cdot 10^{9} cm^{-2} s^{-1}$ and $64 \cdot 10^{9} cm^{-2} s^{-1} \leq Φ_{pp+pep} \leq 65 \cdot 10^{9} cm^{-2} s^{-1}$ (at 1$ σ$ level),

U. Bleyer, A. Zhuk

Mutidimensional cosmological models with $n\left( n\geq 2\right) $ Einstein spaces $M_i\left( i=1,\ldots ,n\right) $ are investigated. The cosmological constant and homogeneous minimally coupled scalar field as a matter sources are considered. The scalar field has a potential of general form depending on the scalar field as well as on the scale factors of $M

N. Angelescu, S. Romano, V. A. Zagrebnov

Extending previous rigorous results, we prove existence of an ordering transition at finite temperature for a class of nematogenic lattice models, where spins are associated with a one- or two-dimensional lattice, and interact via long-range potentials.

Ralf Hempfling

In grand unified theories (GUT) based on SO(10) all fermions of one generation are embedded in a single representation. As a result, the top quark, the bottom quark, and the $τ$ lepton have a universal Yukawa coupling at the GUT scale. This implies a very large ratio of Higgs vacuum expectation values, $\tanb \simeq m_t/m_b$. We analyze the naturalness of su

Denis Juriev

These three topics are an attempt to explicate some curiosities of the inverse problem of representation theory (i.e. having a set of operators to describe the "correct" algebraic object, which is represented by them) on simple examples related to the Lie algebra sl(2,C). Such consideration maybe regarded as toy one for analogous infinite dimensional

Sven Sandow, Steffen Trimper, David Mukamel

The ionic conductivity of mixed alkali glasses exhibits a deep minimum as a function of the relative concentrations of the two alkali ions. To study this behaviour we consider a simple one-dimensional model for asymmetric diffusion of two kinds of particles. Different particles are assumed to repulse each other. We consider two versions of the model: with or

Claude Bourrely, Jacques Soffer

We study the production of $W^{\pm}$ and $Z$ gauge bosons in proton-proton and proton-neutron collisions up to a center-of-mass energy $\sqrt s=0.5\ TeV$, in connection with the realistic possibility of having proton-deuteron collisions at RHIC with a high luminosity. We stress the importance of measuring unpolarized cross sections for a better determination

Z. Bern, L. Dixon, D. Dunbar, D. A. Kosower

We review recent progress in calculations of one-loop QCD amplitudes. By imposing the consistency requirements of unitarity and correct behavior as the momenta of two legs become collinear, we construct ansatze for one-loop amplitudes with an arbitrary number of external legs. For supersymmetric amplitudes, which can be thought of as components of QCD amplit

S. L. Adler, Yong-Shi Wu

\noindent We briefly discuss some algebraic and geometric aspects of the generalized Poisson bracket and non--commutative phase space for generalized quantum dynamics, which are analogous to properties of the classical Poisson bracket and ordinary symplectic structure.

A. Bassetto, L. Griguolo

A generalized chiral Schwinger model is studied by means of perturbative techniques. Explicit expressions are obtained, both for bosonic and fermionic propagators, and compared to the ones derived by means of functional techniques. In particular a consistent recipe is proposed to describe the ambiguity occurring in the regularization of the fermionic determi

Ulf H. Danielsson

In this paper, correlation functions of tachyons in the two-dimensional black-hole are studied. The results are shown to be consistent with the prediction of the deformed matrix model.

Katsushi Ito, Hiroaki Kanno

We obtain a new free field realization of $N=2$ super $W_{3}$ algebra using the technique of quantum hamiltonian reduction. The construction is based on a particular choice of the simple root system of the affine Lie superalgebra $sl(3|2)^{(1)}$ associated with a non-standard $sl(2)$ embedding. After twisting and a similarity transformation, this $W$ algebra

Daniel I. Fivel

It is shown that elementary indistinguishability properties of partially polarized mixtures are consistent only with the conventional Hilbert space model of quantum mechanics and a few exotic alternatives. This applies even in low dimensions where quantum logic and Gleason's theorem give either weak or no constraints. Experimental methods for eliminating

E. Papageorgiu

The observed hierarchy of the quark and lepton masses and mixing angles has led to the parametrisation of the mass matrices in powers of the Cabibbo angle and a certain number of zeros. The origin of these ``textures'' may lie in symmetries present at the GUT/string unification scale. We discuss the case of an extra $U(1)$. Symmetric textures with tw

Michael E. Peskin

This is a broad-brush introduction to the theory of spin in quantum field theory, presented at the 1993 SLAC Summer Institute. It may be useful for beginning students.

Andrei L. Kataev, Aleksander V. Sidorov

We describe the results of our recent work on the determination of the value of the parameter $\Lambda_{\overline{MS}}^{(4)}$ and of the $Q^2$-dependence of the Gross--Llewellyn Smith (GLS) sum rule from the experimental data of the CCFR collaboration on neutrino--nucleon deep-inelastic scattering, using the Jacobi polynomials QCD analysis. The obtained resu

Herbi Dreiner, Peter Morawitz

We consider the baryon parity signals at HERA for the case of the MSSM production mechanisms and the decays via the lepton number violating couplings $L_iQ{\bar D}$. We can probe very small Yukawa couplings $\lam' \gsim 3\cdot 10^{-6}$, limited only by the decay length of the LSP. We assume the LSP to be the lightest neutralino and study its decays in de

Pierre Chiappetta

A brief introduction to strong Higgs sector i.e. the possibility of breaking electroweak symmetry without an elementary Higgs is given. Constraints from present LEP data are studied and the discovery potential of future colliders investigated.

Ignati Grigentch, D. V. Vassilevich

We solve perturbative constraints and eliminate gauge freedom for Ashtekar's gravity on de Sitter background. We show that the reduced phase space consists of transverse, traceless, symmetric fluctuations of the triad and of transverse, traceless, symmetric fluctuations of the connection. A part of gauge freedom corresponding to the conformal Killing vec

U. Bleyer, K. A. Bronnikov, S. B. Fadeev, V. N. Melnikov

Exact static, spherically symmetric solutions to the Einstein-Maxwell-scalar equations, with a dilatonic-type scalar-vector coupling, in $D$-dimensional gravity with a chain of $n$ Ricci-flat internal spaces are considered. Their properties and special cases are discussed. A family of multidimensional dilatonic black-hole solutions is singled out, depending

Masakatsu Kenmoku, Kaori Otsuki, Rieko Sakai

The gravitaional force produced by a point particle, like the sun, in the background of the static Einstein universe is studied. Both the approximate solution in the weak field limit and exact solution are obtained. The main properties of the solution are {\it i}) near the point particle, the metric approaches the Schwarzschild one and the radius of its sing

A. M. Tsvelik

The model of Kondo chain with $M$-fold degenerate band of conduction electrons of spin 1/2 at half filling interacting with localized spins $S$ is studied. It is shown that due to the instanton effects the spin sector reveals itself in optical conductivity. Namely, the density of the charge current at large wave vector $k \approx π$ is proportional to the de

Daniel Braun, Yuval Gefen, Gilles Montambaux

We study the magnetic response of mesoscopic quantum dots in the ballistic regime where the mean free path $l_e$ is larger that the size $L$ of the sample, yet smaller than $L (k_F L)^{d-1}$. In this regime, disorder plays an important role. Employing a semiclassical picture we calculate the contribution of long trajectories which are strongly affected by st

K. J. Niskanen, M. J. Alava

The transition in random fiber networks from two-dimensional to three-dimensional planar structure driven by increasing coverage (total fiber length per unit area) is studied with a deposition model. At low coverage the network geometry depends on the scale-free product of fiber length and coverage while at high coverage it depends on a scale-free combinatio

K. Stokbro, N. Chetty, K. W. Jacobsen, J. K. Nørskov

A new method for calculating the total energy of Si systems is presented. The method is based on the effective-medium theory concept of a reference system. Instead of calculating the energy of an atom in the system of interest a reference system is introduced where the local surroundings are similar. The energy of the reference system can be calculated selfc

K. Stokbro, N. Chetty, K. W. Jacobsen, J. K. Nørskov

A new scheme for constructing approximate effective electron potentials within density-functional theory is proposed. The scheme consists of calculating the effective potential for a series of reference systems, and then using these potentials to construct the potential of a general system. To make contact to the reference system the neutral-sphere radius of

Rebecca J. Passonneau, Diane J. Litman

Certain spans of utterances in a discourse, referred to here as segments, are widely assumed to form coherent units. Further, the segmental structure of discourse has been claimed to constrain and be constrained by many phenomena. However, there is weak consensus on the nature of segments and the criteria for recognizing or generating them. We present quanti

Diane J. Litman

Cue phrases may be used in a discourse sense to explicitly signal discourse structure, but also in a sentential sense to convey semantic rather than structural information. This paper explores the use of machine learning for classifying cue phrases as discourse or sentential. Two machine learning programs (Cgrendel and C4.5) are used to induce classification

Tomoaki Matsumoto, Fumitaka Nakamura, Tomoyuki Hanawa

The dynamical instability of a self-gravitating magnetized filamentary cloud was investigated while taking account of rotation around its axis. The filamentary cloud of our model is supported against self-gravity in part by both a magnetic field and rotation. The density distribution in equilibrium was assumed to be a function of the radial distance from the

E. Branchini, R. G. Carlberg

The least action principle (LAP) is a dynamically rigorous method for deriving the history of galaxy orbits. In particular it is an Omega_0 test, predicting current epoch galaxy velocities as a function of position and of the cosmological background. It is most usefully applied to in--falling structures, such as the local group, where its application indicat

Ali Mostafazadeh, Uni. Texas Dissertation, 115 pages, UT-diss-1994

A new supersymmetric proof of the Atiyah-Singer index theorem is presented. The Peierls bracket quantization scheme is used to quantize the supersymmetric classical system corresponding to the index problem for the twisted Dirac operator. The problem of factor ordering is addressed and the unique quantum system that is relevant to the index theorem is analyz

Shawn J. Kolitch, Douglas M. Eardley

We analyze solutions to Friedmann-Robertson-Walker cosmologies in Brans-Dicke theory, where a scalar field is coupled to gravity. Matter is modelled by a $γ$-law perfect fluid, including false-vacuum energy as a special case. Through a change of variables, we reduce the field equations from fourth order to second order, and they become equivalent to a two-di

A. A. Andrianov, F. Cannata, M. V. Ioffe

Within the framework of second order derivative (one dimensional) SUSYQM we discuss particular realizations which incorporate large energy shifts between the lowest states of the spectrum of the superhamiltonian (of Schrödinger type). The technique used in this construction is based on the "gluing" procedure. We study the limit of infinite energy shi

Y-h. Taguchi

The vibrated bed of powder, a vessel that mono disperse glass beads fill and a loud speaker shakes, is investigated numerically with the distinct element method, a kind of molecular dynamics. When the bed is heavily shaken, the displacement vectors of powder have the power spectrum with the dependence upon the wave number $k$ as $k^{-5/3}$. The origin of thi

Lee Smolin, Chopin Soo

We propose that the Chern-Simons invariant of the Ashtekar-Sen connection is the natural internal time coordinate for classical and quantum cosmology. The reasons for this are a number of interesting properties of this functional, which we describe here. 1)It is a function on the gauge and diffeomorphism invariant configuration space, whose gradient is ortho

Philip G. Edmonds

In conversation, a person sometimes has to refer to an object that is not previously known to the other participant. We present a plan-based model of how agents collaborate on reference of this sort. In making a reference, an agent uses the most salient attributes of the referent. In understanding a reference, an agent determines his confidence in its adequa

Frank Wilczek, Chetan Nayak

We derive some physical properties of ideal assemblies of identical particles obeying generalized exclusion statistics. We discuss fluctuations, and in this connection point out a fundamental contrast to conventional quantum statistics. We demonstrate a duality relating the distribution of particles at statistics $g$ to the distribution of holes at statistic

M. Cacciari, M. Greco

The production of $\jpsi$ at large transverse momenta ($\pt > M_\jpsi$) in $p\bar p$ collisions is considered by including the mechanism of fragmentation. Both contributions of fragmentation to $\jpsi$ and of fragmentation to $χ$ states followed by radiative decay to $\jpsi$ are taken into account. The latter is found to be dominant and larger than direct pr

J. Frieman, D. Harari, G. Surpi

Using Fermat's principle, we analyze the effects of very long wavelength gravitational waves upon the images of a gravitationally lensed quasar. We show that the lens equation in the presence of gravity waves is equivalent to that of a lens with different alignment between source, deflector, and observer in the absence of gravity waves. Contrary to a rec

J. J. de Swart, P. M. M. Maessen, TH. A. Rijken

A review is given of the present situation in YN scattering. Special attention is given to the handling of SU(3) in the various meson exchanges. The importance of the almost always ignored contribution of the Pomeron is reiterated.

Alvaro Restuccia, Jorge Stephany

We describe a canonical covariant formulation of the Green-Schwarz Superstring which allows the construction of a new covariant action canonically equivalent to the Green-Schwarz action but subjected only to first class constraints. From this action the correct BRST operator for the quantization of the Green-Schwarz Superstring may be constructed. Also the g

Juan Pablo Lupi, Alvaro Restuccia, Jorge Stephany

We study the interaction between a $p$-brane and $BF$ system constituted by a $(p+1)$-form and a $n-(p+2)$-form B with a metric independent action on a manifold $M^n$. We identify the allowed $(p+1)$-world manifolds sweeped by the $p$-brane as those restricted by the topological condition of being the boundaries of chains in $M^n$. We find the general soluti

V. D. Lyakhovsky

For a certain class of Lie bialgebras $(A,A^*)$ the corresponding quantum universal enveloping algebras $U_q(A)$ are prooved to be equivalent to quantum groups Fun$_q(F^*)$, $F^*$ being the factor group for the dual group $G^*$. This property can be used to simplify the process of quantization. The described class appears to be wide enough to contain all the

V. D. Lyakhovsky

The elements of the wide class of quantum universal enveloping algebras are prooved to be Hopf algebras $H$ with spectrum $Q(H)$ in the category of groups. Such quantum algebras are quantum groups for simply connected solvable Lie groups $P(H)$. This provides utilities for a new algorithm of constructing quantum algebras especially useful for nonsemisimple o

Carl M. Bender, Stefan Boettcher

This paper extends an earlier high-temperature lattice calculation of the renormalized Green's functions of a $D$-dimensional Euclidean scalar quantum field theory in the Ising limit. The previous calculation included all graphs through sixth order. Here, we present the results of an eleventh-order calculation. The extrapolation to the continuum limit in

Ralph M. Kaufmann

Starting from a detailed analysis of the structure of pathspaces of the ${\cal A}$-fusion graphs and the corresponding irreducible Virasoro algebra quotients $V(c,h)$ for the ($2,q$ odd) models, we introduce the notion of an admissible pathspace representation. The pathspaces ${\cal P_A}$ over the ${\cal A}$-Graphs are isomorphic to the pathspaces over Coxet

G. Sardanashvily

The well-known geometric approach to field theory is based on description of classical fields as sections of fibred manifolds, e.g. bundles with a structure group in gauge theory. In this approach, Lagrangian and Hamiltonian formalisms including the multiomentum Hamiltonian formalism are phrased in terms of jet manifolds. Then, configuration and phase spaces

Neil Marcus

By "untwisting" the construction of Berkovits and Vafa, one can see that the N=1 superstring contains a topological twisted N=2 algebra, with central charge c^ = 2. We discuss to what extent the superstring is actually a topological theory.

D. I. Kazakov

Contrary to the usual case when the quark mass spectrum is defined by that of the quark Yukawa couplings while the vacuum expectation value of the Higgs field remains universal, we suggest to consider the opposite situation. Each generation of quarks and leptons is associated with its own Higgs doublet, while the Yukawa couplings are the same. This situation

Andrija Rašin

We discuss the idea of approximate flavor symmetries. Relations between approximate flavor symmetries and natural flavor conservation and democracy models is explored. Implications for neutrino physics are also discussed.

M. A. Shifman

I give an introduction to the theory of preasymptotic effects based on the systematic OPE/HQET expansion in $1/m_Q$ where $m_Q$ is the heavy quark mass. The general idea is explained in two most instructive examples, with an emphasis on pedagogical aspects. Some important results of the last year are reviewed. In discussing the issue of the quark-hadron dual

V. Barger, M. S. Berger, P. Ohmann, R. J. N. Phillips

The expected trilepton signals from $p \bar p \to χ^\pm_1χ^0_2 \to (χ^0_1\ell^\pmν) (χ^0_1\ell'^+\ell'^-) $ will be converted into hadronically quiet multilepton signals, if the two final $χ^0_1$ have leptonic $R$-parity-violating (RPV) decays $χ^0_1 \to \ell \ell' ν$. We make illustrative calculations of the acceptance for these spectacular RPV

Andre Krzywicki, LPTHE Orsay

The idea that a bubble of misaligned vacuum is sometimes produced in high-energy collisions is reviewed.

Yu. L. Dokshitzer, V. A. Khoze, W. J. Stirling

The emission of energetic gluons in $\tt$ production in $\ee$ annihilation can have important experimental consequences, in particular on top quark mass measurements. We present compact, analytical expressions for the gluon energy distribution and its average value at first order in QCD perturbation theory. Our results are valid for arbitrary masses, collisi

Debajyoti Choudhury, Saurabh D. Rindani

Forward-backward asymmetry in the process $e^+ e^- \rightarrow γZ$ is proposed as a test for $CP$--violating anomalous $γγZ$ and $ γZ Z$ couplings. Longitudinally polarized electron beams may be used to disentangle the effects of these couplings. We estimate possible limits that can be obtained from $e^+ e^-$ colliders at centre-of-mass energies of 200 GeV a

Jean-Paul Blaizot, Edmond Iancu

Hard thermal loops play a central role in the theory of long wavelength excitations of a quark-gluon plasma. We show in this paper how our recent derivation of their generating functional from the Dyson-Schwinger equations sheds light on their semi-classical nature and their remarkable gauge structure. In particular, we show that our kinetic equations can be

Hisakazu Minakata, Hiroshi Nunokawa

We discuss the possibility of testing the principle of equivalence with solar neutrinos. If there exists a violation of the equivalence principle quarks and leptons with different flavors may not universally couple with gravity. The method we discuss employs a quantum mechanical phenomenon of neutrino oscillation to probe into the non-universality of the gra

Ray Renken

A block spin renormalization group approach is proposed for the dynamical triangulation formulation of two-dimensional quantum gravity. The idea is to update link flips on the block lattice in response to link flips on the original lattice. Just as the connectivity of the original lattice is meant to be a lattice representation of the metric, the block links

G. Boyd, Sourendu Gupta, F. Karsch, E. Laermann

Hadronic correlation functions at finite temperature in QCD, with four flavours of dynamical quarks, have been analyzed both above and below the chiral symmetry restoration temperature. We have used both point and extended sources for spatial as well as temporal correlators. The effect of periodic temporal boundary conditions for the valence quarks on the sp

U. Bleyer, V. D. Ivashchuk, V. N. Melnikov, A. Zhuk

A multidimensional cosmological model with space-time consisting of $n (n \ge 2)$ Einstein spaces $M_{i}$ is investigated in the presence of a cosmological constant $Λ$ and a homogeneous minimally coupled scalar field $φ(t)$ as a matter source. Classical and quantum wormhole solutions are obtained for $Λ< 0$ and all $M_{i}$ being Ricci-flat. Classical wormho

U. Bleyer, A. Zhuk

Multidimensional cosmological models with $n~(n > 1)$ Einstein spaces are discussed classically and with respect to canonical quantization. These models are integrable in the case of Ricci flat internal spaces. For negative curvature of the external space we find exact classical solutions modelling dynamical as well as spontaneous compactification of the int

U. Bleyer, V. Ivashchuk

The multidimensional charged dilatonic black hole solution with $n$ internal Ricci-flat spaces is considered. The bound on the mass of the black hole is obtained. In the strong dilatonic coupling limit the critical mass becomes zero. The case $n = \infty$ is also considered.

P. Breitenlohner, D. Maison

We analyze the limiting solution of the Bartnik-McKinnon family and show that its exterior is an extremal Reissner-Nordstrøm black hole and not a new type of non-abelian black hole as claimed in a recent article by Smoller and Wasserman.

G. Sardanashvily

{\it If gravity is a metric field by Einstein, it is a Higgs field.} Gravitation theory meets spontaneous symmetry breaking in accordance with the Equivalence Principle reformulated in the spirit of Klein-Chern geometries of invariants. In gravitation theory, the structure group of the principal linear frame bundle $LX$ over a world manifold $X^4$ is reducib

C. Klimcik, P. Kolnik, A. Pompos

Recently introduced classical theory of gravity in non-commutative geometry is studied. The most general (four parametric) family of $D$ dibensional static spherically symmetric spacetimes is identified and its properties are studied in detail. For wide class of the choices of parameters, the corresponding spacetimes have the structure of asymptotically flat

Shao-Ming Fei, Rui-Hong Yue

By parameterizing the t-j model we present a new electron correlation model with one free parameter for high-temperature superconductivity. This model is of $SU_{q}(1,2)$ symmetry. The energy spectrums are shown to be modulated by the free parameter in the model. The solution and symmetric structures of the Hilbert space, as well as the Bethe ansatz approach

F. S. Zhang, F. Spiegelmann, E. Suraud, V. Fraysse

By using tight binding molecular dynamics simulations, we discuss the possibilities to form (Na$_{19}$)$_2$ and (Na$_{20}$)$_2$ cluster dimers in sodium cluster collisions. In the case of Na$_{19}$ + Na$_{19}$, we show that the formation of a prolate dimer-like (Na$_{19}$)$_2$ maybe depend on the initial relative orientations of the colliding clusters. A sim

T. Ivanov, V. Valtchinov, L. T. Wille

We calculate in a linear response the admittance of a quantum dot out of equilibrium. The interaction between two electrons with opposite spins simultaneously residing on the resonant level is modeled by an Anderson Hamiltonian. The electron correlations lead to the appearence of a new feature in the frequency dependence of the conductance. For certain param

Bill Sutherland, Rudolf A. Römer, B. Sriram Shastry

We present the exact solution to a one-dimensional multicomponent quantum lattice model interacting by an exchange operator which falls off as the inverse-sinh-square of the distance. This interaction contains a variable range as a parameter, and can thus interpolate between the known solutions for the nearest-neighbor chain, and the inverse-square chain. Th

Iwan Jensen

I study the critical behavior of a two-dimensional dimer-trimer lattice model, introduced by Köhler and ben-Avraham [J. Phys. A {\bf 24}, L621 (1991)], for heterogeneous catalysis of the reaction $\frac{1}{2}A_{2}+\frac{1}{3}B_{3} \rightarrow AB$. The model possesses infinitely many absorbing states in which the lattice is saturated by adsorbed particles and

Tao Hong

Degraded text recognition is a difficult task. Given a noisy text image, a word recognizer can be applied to generate several candidates for each word image. High-level knowledge sources can then be used to select a decision from the candidate set for each word image. In this paper, we propose that visual inter-word constraints can be used to facilitate cand

Pavel Etingof

We derive explicit integral formulas for eigenfunctions of quantum integrals of the Calogero-Sutherland-Moser operator with trigonometric interaction potential. In particular, we derive explicit formulas for Jack&#39;s symmetric functions. To obtain such formulas, we use the representation of these eigenfunctions by means of traces of intertwining operators

Hans-Walter Rix, Dan Maoz, Edwin L. Turner, Masataka Fukugita

We investigate the impact of hierarchical galaxy merging on the statistics of gravitational lensing of distant sources. Since no definite theoretical predictions for the merging history of luminous galaxies exist, we adopt a parametrized prescription, which allows us to adjust the expected number of pieces comprising a typical present galaxy at z=0.65. The e

M. Kontsevich

This paper contains an attempt to formulate rigorously and to check predictions in enumerative geometry of curves following from Mirror Symmetry. The main tool is a new notion of stable map. We give an outline of a contsruction of Gromov-Witten invariants for all algebraic projective or closed symplectic manifolds. Mirror Symmetry in the basic example of rat

I. Jack, D. R. T. Jones

We calculate the two-loop $β$-functions for soft supersymmetry-breaking interactions in a general supersymmetric gauge theory, emphasising the role of the evanescent couplings and masses that are generic to a non-supersymmetric theory. We also show that a simple set of conditions sufficient for one-loop finiteness renders a theory two-loop finite, and we spe

Jennifer Chu-Carroll, Sandra Carberry

This paper presents a plan-based architecture for response generation in collaborative consultation dialogues, with emphasis on cases in which the system (consultant) and user (executing agent) disagree. Our work contributes to an overall system for collaborative problem-solving by providing a plan-based framework that captures the {\em Propose-Evaluate-Modi

S. Mrowczynski, B. Mueller

We introduce the Wigner functional representing a quantum field in terms of the field amplitudes and their conjugate momenta. The equation of motion for the functional of a scalar field point out the relevance of solutions of the classical field equations to the time evolution of the quantum field. We discuss the field in thermodynamical equilibrium and find

Vadim Furman, Yigal Shamir

This paper develops in detail a lattice definition of QCD based on the chiral defect fermions recently introduced by Kaplan. The revised version provides missing technical details in the proof that non-singlet axial symmetries become exact in the limit of an infinite fifth dimension. Also several minor errors are corrected.