February 1995 arXiv papers — page 7

Dimitris Kominis, Vassilis Koulovassilopoulos

In a wide class of extensions of the Standard Model there is a scalar resonance with the quantum numbers of the usual Higgs boson but with different couplings to fermions and gauge bosons. Using an effective Lagrangian description, we examine the phenomenology of such a generic nonstandard Higgs boson at the LHC. In particular, we determine the circumstances

Pedro F. Gonzalez-Diaz

We study the dynamics of multiwormhole configurations within the framework of the Euclidean Polyakov approach to string theory, incorporating a modification to the Hamiltonian which leads to a Planckian probability measure for the Coleman parameters $α$ that allows $\frac{1}{2}α^{2}$ to be interpreted as the energy of the quanta of a radiation field on super

Simonetta Frittelli, Carlos N. Kozameh, Ezra T. Newman

Recently there has been developed a reformulation of General Relativity - referred to as {\it the null surface version of GR} - where instead of the metric field as the basic variable of the theory, families of three-surfaces in a four-manifold become basic. From these surfaces themselves, a conformal metric, conformal to an Einstein metric, can be construct

S. Massar, R. Parentani

The energy and particle fluxes emitted by an accelerated two level atom are analysed in detail. It is shown both perturbatively and non perturbatively that the total number of emitted photons is equal to the number of transitions characterizing thermal equilibrium thereby confirming that each internal transition is accompanied by the emission of a Minkowski

Jean-Michel Bismut, John Lott

We prove the vanishing of a certain characteristic class of flat vector bundles when the structure groups of the bundles are contained in GL(N,Z). We do so by explicitly writing the characteristic class as an exact form on the base of the bundle.

Raimundo R dos Santos

We study the Hubbard model on a bilayer with repulsive on-site interactions, $U$, in which fermions undergo both intra-plane ($t$) and inter-plane ($t_z$) hopping. This situation is what one would expect in high-temperature superconductors such as YBCO, with two adjacent CuO$_2$ planes. Magnetic and pairing properties of the system are investigated through Q

I. Vakarchuk, V. Tkachuk, T. Kuliy

The relation between atomic momenta fluctuations and density fluctuations is obtained in frames of mean-field approximation. Using two-time temperature Green functions within Tyablikov approximation the equations for spin excitation energy and damping are obtained. The asymptotics of energy and damping in the long-wave limit are investigated and the anomalou

P. L. Krapivsky, S. Redner

The survival probabilities of a ``prisoner'' diffusing in an expanding cage and a ``daredevil'' diffusing at the edge of a receding cliff are investigated. When the diffuser reaches the boundary, he dies. For ``marginal'' boundary motion, i.e., the cage length grows as $\sqrt{At}$ or the cliff location recedes as $x_0(t)=-\sqrt{At}$ a

Jewan Kim, Jungdae Kim, Taejin Lee

Assuming that the superconductivity which is described by the low energy effective action of the anyon system may be type II, we discuss its characteristics. We also study physical properties of the Chern-Simons vortices, which may be formed as the external magnetic field is applied to the system, such as their statistics, the free energy of single vortex an

A. Rauh, T. Zachrau, J. Zoller

In the subcritical interval of the Reynolds number 4320\leq R\leq R_c\equiv 5772, the Navier--Stokes equations of the two--dimensional plane Poiseuille flow are approximated by a 22--dimensional Galerkin representation formed from eigenfunctions of the Orr--Sommerfeld equation. The resulting dynamical system is brought into a generalized normal form which is

Jan Alexandersson, Elisabeth Maier, Norbert Reithinger

We present the dialogue component of the speech-to-speech translation system VERBMOBIL. In contrast to conventional dialogue systems it mediates the dialogue while processing maximally 50% of the dialogue in depth. Special requirements like robustness and efficiency lead to a 3-layered hybrid architecture for the dialogue module, using statistics, an automat

Gerhard Hummer

Ewald summation is widely used to calculate electrostatic interactions in computer simulations of condensed-matter systems. We present an analysis of the errors arising from truncating the infinite real- and Fourier-space lattice sums in the Ewald formulation. We derive an optimal choice for the Fourier-space cutoff given a screening parameter $η$. We find t

Boqi Wang

We propose that cooling outflows from star-forming dwarf galaxies that are spatially correlated with but unbound to bright galaxies may account for the low column QSO Ly$α$ forests, providing an explanation for both the heavy elements recently detected in them and the large sizes associated with them. Thus, we suggest that structure formations in the early u

B. V. Komberg, A. V. Kravtsov, V. N. Lukash

We report the investigation of spatial distribution of quasars using two different methods: the statistical study by means of 2-point correlation function and direct search for structures such as previously reported Large Quasar Groups. Having analyzed the combined sample of eight homogeneous quasar surveys (totalling near 2200 objects), we detected strong c

Ken-ichi Nakao, Naoteru Gouda, Takeshi Chiba, Satoru Ikeuchi

We investigate the distance-redshift relation in the simple void model. As discussed by Moffat and Tatarski, if the observer stays at the center of the void, the observed Hubble parameter is not so different from the background Hubble parameter. However, if the position of observer is off center of the void, we must consider the peculiar velocity correction

Andrea Bruno, Kenji Matsuki

The purpose of this paper is two-fold. The first is to give a tutorial introduction to the Sarkisov program, a 3-dimensional generalization of Castelnuovo-Nöther Theorem ``untwisting" birational maps between Mori fiber spaces, which was recently established by Corti after Sarkisov and Reid. The second is an attempt to give a logarithmic generalization of

Stephen M. Griffies, Eli Tziperman

The interdecadal variability of a stochastically forced four-box model of the oceanic meridional thermohaline circulation (THC) is described and compared to the THC variability in the coupled ocean-atmosphere GCM of Delworth, Manabe, and Stouffer (1993). The box model is placed in a linearly stable thermally dominant mean state under mixed boundary condition

Matthias Neubert

Recently, we have developed a formalism to evaluate QCD loop diagrams with a single virtual gluon using a running coupling constant at the vertices. This corresponds to an all-order resummation of certain terms (the so-called renormalon chains) in a perturbative series and provides a generalization of the scale-setting prescription of Brodsky, Lepage and Mac

Georg B. Larsen, Jes Madsen

Mixed dark matter models with one low-mass (e.g. 2.4eV) neutrino flavor are shown to be in good agreement with observations if the neutrinos have non-zero chemical potentials. This agreement holds (except for the problem with a low-age Universe) even for high values of the Hubble-parameter. Massless neutrinos with non-zero chemical potentials may reconcile c

Konrad Kuijken, John Dubinski

We describe methods for setting up self-consistent disk-bulge-halo galaxy models. The bulge and halo distribution functions (\df) are functions of $E$ and $L_z$ only. The halo's flattening and rotation can be specified. The disk \df\ is a function of $E$ and $L_z$ and a third ``integral'', $E_z$, the vertical energy, which is approximately conser

S. M. Bilenky, C. Giunti

It is shown that the future SNO and Super-Kamiokande experiments, in which high energy $^8\mathrm{B}$ neutrinos will be detected through the observation of CC, NC and $ν$--$e$ elastic scattering processes, could allow to reveal in a model independent way the presence of sterile neutrinos in the flux of solar neutrinos on the earth. Lower bounds for different

A. Carlini, J. Greensite

We consider quantization of the Baierlein-Sharp-Wheeler form of the gravitational action, in which the lapse function is determined from the Hamiltonian constraint. This action has a square root form, analogous to the actions of the relativistic particle and Nambu string. We argue that path-integral quantization of the gravitational action should be based on

P. H. C. Magnee, B. J. van Wees, T. M. Klapwijk, W. van de Graaf

We have investigated experimentally the electronic transport properties of a two-dimensional electron gas (2DEG) present in an AlSb/InAs/AlSb quantum well, where part of the toplayer has been replaced by a superconducting Nb strip, with an energy gap $Δ_0$. By measuring the lateral electronic transport underneath the superconductor, and comparing the experim

D. Klakow, M. Weber, P. -G. Reinhard

Two microscopic theories for multiple resonances in nuclei are compared, n-particle-hole RPA and quantized Time-Dependent Hartree-Fock (TDHF). The Lipkin-Meshkov-Glick model is used as test case. We find that quantized TDHF is superior in many respects, except for very small systems.

S. V. Akulinichev

We analize two reactions: the electroproduction at small x and the Drell-Yan production by protons on nuclei. We show that nuclear shadowing in electroproduction is larger if the virtuality of inter- mediate hadrons is properly taken into account. In the Drell-Yan production, initial state interactions of fast partons are included. With this input, the exces

M. A. Lisa, S. Albergo, F. Bieser, F. P. Brady

A systematic study of energy spectra for light particles emitted at midrapidity from Au+Au collisions at E=0.25-1.15 A GeV reveals a significant non-thermal component consistent with a collective radial flow. This component is evaluated as a function of bombarding energy and event centrality. Comparisons to Quantum Molecular Dynamics (QMD) and Boltzmann-Uehl

Donald E. Knuth

A set partition technique that is useful for identifying wires in cables can be recast in the language of 0--1 matrices, thereby resolving an open problem stated by R.~L. Graham in Volume 1 of this journal. The proof involves a construction of 0--1 matrices having row and column sums without gaps.

Duane M. Broline, Daniel E. Loeb

Certain endgame considerations in the two-player Nigerian Mancala-type game Ayo can be identified with the problem of finding winning positions in the solitaire game Tchoukaitlon. The periodicity of the pit occupancies in $s$ stone winning positions is determined. Given $n$ pits, the number of stones in a winning position is found to be asymptotically bounde

Erensto Damiani, Ottavio D'Antona, Daniel E. Loeb

We review the Green/Kleitman/Leeb interpretation of de Bruijn's symmetric chain decomposition of ${\cal B}_{n}$, and explain how it can be used to find a maximal collection of disjoint symmetric chains in the nonsymmetric lattice of partitions of a set.

Daniel E. Loeb

New proofs are given for Monjardet's theorem that all strong simple games (i.e., ipsodual elements of the free distributive lattice) can be generated by the median operation. Tighter limits are placed on the number of iterations necessary. Comparison is drawn with the $χ$ function which also generates all strong simple games.

Andrew J. Lazarus, Daniel E. Loeb, James G. Propp, Daniel Ullman

A Richman game is a combinatorial game in which, rather than alternating moves, the two players bid for the privilege of making the next move. We consider both the case where the players pay each other and the case where the players pay a neutral third party. We find optimal strategies considering both the case where the players know how much money their opp

Daniel E. Loeb

We take advantage of the combinatorial interpretations of many sequences of polynomials of binomial type to define a sequence of symmetric functions corresponding to each sequence of polynomials of binomial type. We derive many of the results of Umbral Calculus in this context including a Taylor's expansion and a binomial identity for symmetric functions

Daniel E. Loeb

An extension of the theory of the Iterated Logarithmic Algebra gives the logarithmic analog of a Sheffer or Appell sequence of polynomials. This leads to several examples including Stirling's formula and a logarithmic version of the Euler-MacLaurin summation formula. Grâce à une généralisation de la théorie de l'algèbre des logarithmes itérés, on def

Daniel E. Loeb

We generalize the Umbral Calculus of G-C. Rota by studying not only sequences of polynomials and inverse power series, or even the logarithms studied in, but instead we study sequences of formal expressions involving the iterated logarithms and x to an arbitrary real power. Using a theory of formal power series with real exponents, and a more general definit

Daniel E. Loeb

We pose the question of what is the best generalization of the factorial and the binomial coefficient. We give several examples, derive their combinatorial properties, and demonstrate their interrelationships. On cherche ici à déterminer est la meilleure généralisation possible des factorielles et des coefficients du binôome. On s'interesse à plusieurs e

Daniel E. Loeb

We generalize the Stirling numbers of the first kind $s(a,k)$ to the case where $a$ may be an arbitrary real number. In particular, we study the case in which $a$ is an integer. There, we discover new combinatorial properties held by the classical Stirling numbers, and analogous properties held by the Stirling numbers $s(n,k)$ with $n$ a negative integer. On

Daniel E. Loeb

We define the Artinian and Noetherian algebra which consist of formal series involving exponents which are not necessarily integers. All of the usual operations are defined here and characterized. As an application, we compute the algebra of symmetric functions with nonnegative real exponents. The applications to logarithmic series and the Umbral calculus ar

Alessandro Di Bucchianico, Daniel E. Loeb

We characterize the Sheffer sequences by a single convolution identity $$ F^{(y)} p_{n}(x) = \sum _{k=0}^{n}\ p_{k}(x)\ p_{n-k}(y)$$ where $F^{(y)}$ is a shift-invariant operator. We then study a generalization of the notion of Sheffer sequences by removing the requirement that $F^{(y)}$ be shift-invariant. All these solutions can then be interpreted as coco

S. Anelli, Ernesto Damiani, Ottavio D'Antona, Daniel E. Loeb

Given a universe of discourse $U$, a {\em multiset} can be thought of as a function $M$ from $U$ to the natural numbers ${\bf N}$. In this paper, we define a {\em hybrid set} to be any function from the universe $U$ to the integers ${\bf Z}$. These sets are called hybrid since they contain elements with either a positive or negative multiplicity. Our goal is

Anne Bottreau, Alessandro Di Bucchianico, Daniel E. Loeb

We are developing a Maple package of functions related to Rota's Umbral Calculus. A Mathematica version of this package is being developed in parallel.

Alessandro Di Bucchianico, Daniel E. Loeb

We prove the following conjecture of Narayana: there are no dominance refinements of the Smirnov two-sample test if and only if the two sample sizes are relatively prime.

Alessandro Di Bucchianico, Daniel E. Loeb

We characterize those linear operators that can be expressed as a sum over k of terms of the form f_k(D) x^k and give several examples.

Daniel E. Loeb, Gian-Carlo Rota

We retrace the recent history of the Umbral Calculus. After studying the classic results concerning polynomial sequences of binomial type, we generalize to a certain type of logarithmic series. Finally, we demonstrate numerous typical examples of our theory. Nous passons en revue ici les resultats recents du calcul ombral. Nous nous interessons tout d'ab

Vladimir Kanovei, Michiel van Lambalgen

We prove that a Spector--like ultrapower extension $\gN$ of a countable Solovay model $\gM$ (where all sets of reals are Lebesgue measurable) is equal to the set of all sets constructible from reals in a generic extension $\gM[\al]$ where $\al$ is a random real over $\gM.$ The proof involves an almost everywhere uniformization theorem in the Solovay model.

Lusheng Chen, Gerald Dunne, Kurt Haller, Edwin Lim-Lombridas

In this paper we investigate the canonical quantization of a non-Abelian topologically massive Chern-Simons theory in which the gauge fields are minimally coupled to a multiplet of scalar fields in such a way that the gauge symmetry is spontaneously broken. Such a model produces the Chern-Simons-Higgs mechanism in which the gauge excitations acquire mass bot

YARON OZ

The topological description of $2D$ string theory at the self-dual radius is studied in the algebro-geometrical formulation of the $A_{k+1}$ topological models at $k=-3$. Genus zero correlators of tachyons and their gravitational descendants are computed as intersection numbers on moduli space and compared to $2D$ string results. The interpretation of negati

Luciano Girardello, Amit Giveon, Massimo Porrati, Alberto Zaffaroni

't Hooft construction of free energy, electric and magnetic fluxes, and of the partition function with twisted boundary conditions, is extended to the case of $N=4$ supersymmetric Yang-Mills theories based on arbitrary compact, simple Lie groups. The transformation of the fluxes and the free energy under S-duality is presented. We consider the partition

C. Neves, E. M. C. de Abreu, C. Wotzasek

We show that a complete covariantization of the chiral constraint in the Floreanini-Jackiw necessitates an infinite number of auxiliary Wess-Zumino fields otherwise the covariantization is only partial and unable to remove the nonlocality in the chiral boson operator. We comment on recent works that claim to obtain covariantization through the use of Batalin

William A. Ponce, Arnulfo Zepeda

We introduce a three family extension of the Pati-Salam model which is anomaly-free and contains in a single irreducible representation the known quarks and leptons without mirror fermions. Assuming that the breaking of the symmetry admits the implementation of the survival hypothesis, we calculate the mass scales using the renormalization group equation. Fi

Xiangdong Ji

In this talk, I focus on the quark-gluon structure of hadrons probed using high-energy hadron beams. I start with a brief review on recent major achievements in measuring parton distributions of the nucleon, pion, and kaon, with hadron facilities at CERN and FNAL\@. Then I discuss a number of outstanding questions and interesting physics issues in the field,

B. I. Ermolaev, S. I. Manayenkov, M. G. Ryskin

The small x behaviour of the non-singlet structure function is studied within the double logarithmic approximation (DLA) of perturbative QCD. Since there is neither $k_T$ nor $θ$ ordering in the ladder Feynman graphs, the predicted non-singlet quark densities for the HERA kinematical range ($x\sim 10^{-3}$) exceed the values calculated from the small-$x$ app

Claude Bourrely, Jacques Soffer

We recall our recent description of quark parton densities of the proton at $Q^2=4 GeV^2$ in terms of Fermi-Dirac distributions parametrized with very few free parameters. We have also proposed some simple assumptions to relate unpolarized and polarized quark parton densities which lead to a fair description of the spin-dependent structure functions $xg^p_1(

J. L. Feng, H. Murayama, M. E. Peskin, X. Tata

Up to now, almost all discussion of supersymmetry at future colliders has been concerned with particle searches. However, if candidates for supersymmetric particles are found, there is much more that we will want to know about them. Supersymmetry predicts quantitative relations among the couplings and masses of supersymmetric particles. We discuss the prospe

Markus A. Luty, Raman Sundrum

We compute the electromagnetic mass differences of mesons containing a single heavy quark in terms of measurable data using QCD-based arguments in heavy-quark effective theory. We derive an unsubtracted dispersion relation that shows that the mass differences are calculable in terms of the properties of the lowest-lying physical intermediate states. We then

M. Bishai

We have measured the weak decay asymmetry parameters ($\aLC $) for two \LC\ decay modes. Our measurements are $\aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} $ for the decay mode $Λ_c^+ \to Λπ^+ $ and $\aLC = -0.45\pm 0.31 \pm 0.06$ for the decay mode $Λ_c \to Σ^+π^0 $. By combining these measurements with the previously measured decay rates, we have extracted the p

B. Bergerhoff, D. Litim, S. Lola, C. Wetterich

We investigate the phase transition in the three-dimensional abelian Higgs model for N complex scalar fields, using the gauge-invariant average action Γ_{k}. The dependence of Γ_{k} on the effective infra-red cut-off k is described by a non-perturbative flow equation. The transition turns out to be first- or second-order, depending on the ratio between scala

Beat Ammon, Matthias Troyer, Hirokazu Tsunetsugu

We have used exact diagonalization and quantum Monte Carlo methods to study the one-dimensional {t-J} model including the three-site hopping term derived from the strong coupling limit of the Hubbard model. The three-site term may be important to superconducting correlations since it allows direct hopping of local singlet electron pairs. The phase diagram is

Francesc Ribas

We present some variations affecting the association measure and thresholding on a technique for learning Selectional Restrictions from on-line corpora. It uses a wide-coverage noun taxonomy and a statistical measure to generalize the appropriate semantic classes. Evaluation measures for the Selectional Restrictions learning task are discussed. Finally, an e

A. Vagelatos, T. Triantopoulou, C. Tsalidis, D. Christodoulakis

In this paper we present an interactive spelling correction system for Modern Greek. The entire system is based on a morphological lexicon. Emphasis is given to the development of the lexicon, especially as far as storage economy, speed efficiency and dictionary coverage is concerned. Extensive research was conducted from both the computer engineering and li

John C. Tsai, William G. Mathews

We consider the lifecycle of dust introduced into the hot interstellar medium in isolated elliptical galaxies. Dust grains are ejected into galactic-scale cooling flows in large ellipticals by normal mass loss from evolving red giants. Newly introduced dust rapidly enters the hot gas environment and is sputtered away by thermal collisions with ions. Before t

R. Jimenez, U. G. Jorgensen, P. Thejll, J. MacDonald

We present here results of stellar evolution calculations that include the latest advances in radiative opacities and neutrino cooling, and discuss on the basis of these models how the internal stellar structure responds to mass-loss from the stellar surface. This problem has particular importance for the development of semi-analytical algorithms for effi ci

Boris Chibisov, Ariel R. Zhitnitsky

We discuss the various aspects of two-dimensional $QCD_{2}(N\rightarrow\infty)$ (the 't Hooft model\cite{Hooft}). Our main interest (motivated by the corresponding analysis in the four dimensional QCD) is the vacuum structure of the theory. We use the very general methods in the analysis, such as dispersion relations and duality in order to relate the kn

Takashi Kimura, Jim Stasheff, Alexander A. Voronov

We propose an explicit relation between the cohomology of compactified and noncompactified moduli spaces of algebraic curves with punctures. This relationship generalizes one between commutative algebras and Lie algebras proposed by Lazard, Kontsevich and Ginzburg and Kapranov. More explicitly, we show that the cohomology of one moduli space is the graph com

Stephen M. Griffies, Kirk Bryan

Predictability of the North Atlantic thermohaline circulation (THC) variability as simulated in the GFDL coupled ocean-atmosphere general circulation model is established for a set of ensemble experiments. The ensembles consist of identical oceanic initial conditions underneath a model atmosphere chosen randomly from the model climatology. This experimental

R. Rapp, J. Wambach

Within the Matsubara formalism we derive expressions for the pion self-energy and the two-pion propagator in a hot pion gas. These quantities are used to selfconsistently calculate the in-medium $ππ$ amplitude beyond the quasiparticle approximation (QPA). The results are shown to differ significantly from QPA-based calculations. We also examine the impact of

B. de Carlos, J. A. Casas

We evaluate the branching ratio BR($b\rightarrow s,γ$) in the minimal supersymmetric standard model (MSSM), determining the corresponding phenomenological restrictions on two attractive supergravity scenarios, namely minimal supergravity and a class of models with a natural solution to the $μ$ problem. We have included in the calculation some one--loop refin

Ady Stern, Bertrand I. Halperin

We consider a two dimensional electron system in an external magnetic field at and near an even denominator Landau level filling fraction. Using a fermionic Chern--Simons approach we study the description of the system's low energy excitations within an extension of Landau's Fermi liquid theory. We calculate perturbatively the effective mass and the

Savitri V. Iyer, Carlos N. Kozameh, Ezra T. Newman

We reformulate the standard local equations of general relativity for asymptotically flat spacetimes in terms of two non-local quantities, the holonomy $H$ around certain closed null loops on characteristic surfaces and the light cone cut function $Z$, which describes the intersection of the future null cones from arbitrary spacetime points, with future null

S. J. Poletti, J. Twamley, D. L. Wiltshire

The properties of static spherically symmetric black holes, which are both electrically and magnetically charged, and which are coupled to the dilaton in the presence of a cosmological constant, Lambda, are considered. It is shown that apart from the Reissner-Nordstrom-de Sitter solution with constant dilaton, such solutions do not exist if Lambda > 0 (in ar

Yu-Kui Zhou

The fused six-vertex models with open boundary conditions are studied. The Bethe ansatz solution given by Sklyanin has been generalized to the transfer matrices of the fused models. We have shown that the eigenvalues of transfer matrices satisfy a group of functional relations, which are the $su$(2) fusion rule held by the transfer matrices of the fused mode

B. L. Johnson, A. S. Sachrajda, G. Kirczenow, Y. Feng

We have introduced a controllable nano-scale incursion into a potential barrier imposed across a two-dimensional electron gas, and report on the phenomena that we observe as the incursion develops. In the quantum Hall regime, the conductance of this system displays quantized plateaus, broad minima and oscillations. We explain these features and their evoluti

R. S. Ward

There are two-dimensional Toda field equations corresponding to each (finite or affine) Lie algebra. The question addressed in this note is whether there exist integrable discrete versions of these. It is shown that for certain algebras (such as $A_n$, $A_n^{(1)}$ and $B_n$) there do, but some of these systems are defined on the half-plane rather than the fu

M. Czachor, K. Rzazewski

The Roentgen correction to the dipole interaction term leads to an additional divergency which can be eliminated for infinitely heavy atoms. For M < infinity a probability of emission in a given direction is represented by a divergent integral.

Karl Svozil

The classical methods used by recursion theory and formal logic to block paradoxes do not work in quantum information theory. Since quantum information can exist as a coherent superposition of the classical ``yes&#39;&#39; and ``no&#39;&#39; states, certain tasks which are not conceivable in the classical setting can be performed in the quantum setting. Clas

A. Lorek, J. Wess

The dynamical algebra of the q-deformed harmonic oscillator is constructed. As a result, we find the free deformed Hamiltonian as well as the Hamiltonian of the deformed oscillator as a complicated, momentum dependent interaction Hamiltonian in terms of the usual canonical variables. Furthermore we construct a well-defined algebra SU$_q$(1,1) with consistent

I. B. Khriplovich

In heavy nuclei there is a parametrical suppression, $\;\sim A^{-1/3}\;$, of T-odd, P-odd matrix elements as compared to T-even, P-odd ones.

I. B. Khriplovich

Atomic experiments bring meaningful and valuable information on fundamental symmetries. The hypothesis of a large ($\sim 100$ eV) P-odd weak matrix element between single-particle states in heavy nuclei is inconsistent with the results of atomic PNC experiments. Upper limits on CP-violation obtained in atomic and molecular spectroscopy are as informative as

S. Wycech, A. M. Green, J. A. Niskanen

Using multiple scattering theory the scattering lengths of $η$ mesons on helium nuclei are calculated and checked against final state $η$ interactions from the $pd \rightarrow η^3$He and $dd \rightarrow η^4$He reactions. The existence of an $η^4$He quasibound state is indicated.

Xin-Nian Wang, Miklos Gyulassy

Based on QCD-inspired models for multiple jets production, we developed a Monte Carlo program to study jet and the associated particle production in high energy $pp$, $pA$ and $AA$ collisions. The physics behind the program which includes multiple minijet production, soft excitation, nuclear shadowing of parton distribution functions and jet interaction in d

Antti J. Niemi

Periodic classical trajectories are of fundamental importance both in classical and quantum physics. Here we develop path integral techniques to investigate such trajectories in an arbitrary, not necessarily energy conserving hamiltonian system. In particular, we present a simple derivation of a lower bound for the number of periodic classical trajectories.

J. Fleischer, O. V. Tarasov

In a recent paper \cite{ft} a new powerful method to calculate Feynman diagrams was proposed. It consists in setting up a Taylor series expansion in the external momenta squared. The Taylor coefficients are obtained from the original diagram by differentiation and putting the external momenta equal to zero. It was demonstrated that by a certain conformal map

L. Cooper, G. E. Stedman

A ring-laser experiment, similar to the Canterbury ring laser, to detect axion- and {\sc qed}-induced vacuum birefringence is proposed. It uses a slowly modulated magnetic field and a novel polarization geometry. Both axion coupling and vacuum birefringence would modulate the Sagnac beat frequency. A null result could place sensitive bounds on the axion mass

A. Dobado, M. T. Urdiales

In this work we report on the results obtained in a detailed and systematical study of the possibility to measure the parameters appearing in the electroweak chiral lagrangian. The main novelty of our approach is that we do not use the Equivalence Theorem and therefore we work explicitly with all the gauge boson degrees of freedom.

Eduardo de Rafael

These lectures are an introduction to the subject of chiral effective Lagrangians of the Standard Model and their applications, mostly in the sector of non--leptonic kaon decays, with special emphasis on CP--violation. The first lecture gives an introduction to the phenomenological description of the $K^0-\bar{K}^0$ system and $K\ra ππ$ decays. In the second

O. W. Greenberg

I survey the use of the Haag expansion as a technique to solve quantum field theories. After an exposition of the asymptotic condition and the Haag expansion, I report the results of applying the Haag expansion to several quantum field theories, including galilean-invariant theories, matter at finite temperature (using the BCS model of superconductivity as a

R. Roncaglia, D. B. Lichtenberg, E. Predazzi

The Feynman-Hellmann theorem and semiempirical mass formulas are used to predict the masses of baryons containing one or two heavy quarks. In particular, the mass of the $Λ_b$ is predicted to be $5620 \pm 40$ MeV, a value consistent with measurements.

G. Sardanashvily

In gravitation theory, the realistic fermion matter is described by spinor bundles associated with the cotangent bundle of a world manifold $X$. In this case, the Dirac operator can be introduced. There is the 1:1 correspondence between these spinor bundles and the tetrad gravitational fields represented by sections of the quotient $\Si$ of the linear frame

Mauro Carfora, Kamilla Piotrkowska

We discuss the averaging hypothesis tacitly assumed in standard cosmology. Our approach is implemented in a &#34;3+1&#34; formalism and invokes the coarse graining arguments, provided and supported by the real-space Renormalization Group (RG) methods. Block variables are introduced and the recursion relations written down explicitly enabling us to characteri

T Dereli, M Onder, Robin W Tucker

We examine a 1 parameter class of actions describing the gravitational interaction between a pair of scalar fields and Einsteinian gravitation. When the parameter is positive the theory corresponds to an axi-dilatonic sector of low energy string theory. We exploit an SL(2,R) symmetry of the theory to construct a family of electromagnetically neutral solution

T Dereli, Robin W Tucker

We examine the axi-dilatonic sector of low energy string theory and demonstrate how the gravitational interactions involving the axion and dilaton fields may be derived from a geometrical action principle involving the curvature scalar associated with a non-Riemannian connection. In this geometry the antisymmetric tensor 3-form field determines the torsion o

S. W. Hawking

Various calculations of the $S$ matrix have shown that it seems to be non unitary for interacting fields when there are closed timelike curves. It is argued that this is because there is loss of quantum coherence caused by the fact that part of the quantum state circulates on the closed timelike curves and is not measured at infinity. A prescription is given

Hernan Makse

A simple model for an interface moving in a disordered medium is presented. The model exhibits a transition between the two universality classes of interface growth phenomena. Using this model, it is shown that the application of constraints to the local slopes of the interface produces avalanches of growth, that become relevant in the vicinity of the depinn

C. O&#39;Donovan, J. C. Carbotte

For a tight binding model with nearest neighbour attraction and a small orthorhombic distortion, we find a phase diagram for the gap at zero temperature which includes three distinct regions as a function of filling. In the first, the gap is a mixture of mainly $d$-wave with a smaller extended $s$-wave part. This is followed by a region in which there is a r

Achim Rosch, Thilo Kopp

We investigate the low temperature behavior of a heavy particle (mass $M$) in a fermionic bath. An effective action is considered which exactly implements the orthogonality catastrophe. It is equivalent to a model of local bosons coupling via a long-range interaction to the particle. The saddlepoint solution for the heavy particle propagator yields a finite

G. Hackenbroich, H. A. Weidenmueller

Motivated by a recent experiment by Yacoby et al.\ [preprint, 1994], we calculate magnitude and phase $α$ of the transmission amplitude through a quantum dot. We work in the Coulomb blockade regime, assume the electrons not to interact, and consider tunneling through isolated resonances. Assuming a non--resonant background, we find that $α$ increases by $2 π

David Carter

I describe a compiler and development environment for feature-augmented two-level morphology rules integrated into a full NLP system. The compiler is optimized for a class of languages including many or most European ones, and for rapid development and debugging of descriptions of new languages. The key design decision is to compose morphophonological and mo

Antonietta Tomasulo, Mushti V. Ramakrishnai

The shifts of the electronic absorption spectra of GaAs and GaP semiconductor clusters are calculated using accurate pseudopotentials. In the absence of experimental data at present, these calculations provide estimates of expected spectral shifts in these clusters. In addition, these calculations show that Coulomb interaction between the electron and hole d

Jun Pan, Atul Bahel, Mushti V. Ramakrishna

We determined the structures of silicon clusters in the 11-14 atom size range using the tight-binding molecular dynamics method. These calculations reveal that \Si{11} is an icosahedron with one missing cap, \Si{12} is a complete icosahedron, \Si{13} is a surface capped icosahedron, and \Si{14} is a 4-4-4 layer structure with two caps. The characteristic fea

Atul Bahel, Mushti V. Ramakrishna

Tight-binding molecular dynamic simulations have revealed that Si$_{12}$ is an icosahedron with all atoms on the surface of an approximately 5 Å~ diameter sphere. This is the most spherical cage structure for silicon clusters in the 2-13 atom size range.

Tomaz Prosen

A new method for exact quantization of general bound Hamiltonian systems is presented. It is the quantum analogue of the classical Poincare Surface Of Section (SOS) reduction of classical dynamics. The quantum Poincare mapping is shown to be the product of the two generalized (non-unitary but compact) on-shell scattering operators of the two scattering Hamil