April 1996 arXiv papers — page 2

R. M. Weiner

It is shown that there exists an intimate relationship between Bose Einstein correlations and quantum field theory. On the one hand several essential aspects of BEC cannot be understood and even formulated without second quantization. On the other hand BEC can serve as a unique tool in the investigation of modern field theory and in particular of the standar

Y. J. Feng, O. Hamidi-Ravari, C. S. Lam

A new approach is introduced to study QCD amplitudes at high energy and comparatively small momentum transfer. Novel cut diagrams, representing resummation of Feynman diagrams, are used to simplify calculation and to avoid delicate cancellations encountered in the usual approach. Explicit calculation to the 6th order is carried out to demonstrate the advanta

S. A. Abel

It is argued that the Next-to-MSSM (NMSSM) is unnatural from the point of view of cosmology and fine tuning. In particular, such singlet extensions to the MSSM do not provide a simple solution to the `$μ$-problem'. Models with singlets can be constructed using gauged-$R$ symmetry or target space duality. However their superpotentials have terms in additi

J. M. Virey

Around 1999, thanks to the RHIC Spin Collaboration (RSC), the Relativistic Heavy Ion Collider (RHIC) will be used as a polarized proton-proton collider. A new handed interaction between quark subconstituents, which could explain the excess of large E_T jet found by the CDF collaboration, could be at the origin of some small parity violating effects in one-je

J. A. Gracey

The large N_f self-consistency programme is reviewed. As an application the QCD beta-function is computed at O(1/N_f) and the anomalous dimensions of polarized twist-2 singlet operators are determined at the same order.

P. Colangelo, F. De Fazio

We compute by QCD sum rules the matrix elements of the relevant four-quark operators appearing in the expression of the $Λ_b$ inclusive decay rates at the order $1/m_b^3$. The results suggest that $1/m_b^3$ corrections are not responsible of the observed difference between the lifetime of $Λ_b$ and $B_d$.

Bo-Qiang Ma

A brief summary on the Wigner rotation effect in the understanding of the proton spin ``crisis" related with the Ellis-Jaffe sum rule violation, and on the proton-neutron isospin symmetry breaking explanation of the Gottfried sum rule violation. The proton spin could be fully provided by the spin sum of quarks if one considers the Wigner rotation effect

A. V. Berezhnoy, V. V. Kiselev, A. K. Likhoded

In the framework of perturbative QCD in the fourth order over the $α_s$ coupling constant for the production of two pairs of quarks and in the model of weak binding of the quarks into meson, the analysis of the hadronic production of mesons, containing $b$-quark, is performed, and a minimal transverse momentum is determined, so that at the momenta greater th

Thomas G. Rizzo

We examine the capability of the NLC to determine the mass as well as the couplings to leptons and $b$-quarks of a new neutral gauge boson below production threshold. By using data collected at several different values of $\sqrt s$, we demonstrate how this can be done in a model-independent manner. [To appear in {\it Physics and Technology of the Next Linear

K. Scharnhorst

In this paper a method previously employed by Salmhofer to establish an exact equivalence of the one-flavour strong coupling lattice Schwinger model with Wilson fermions to some 8-vertex model is applied to the case with two flavours. As this method is fairly general and can be applied to strong coupling QED and purely fermionic models with any (sufficiently

K. C. K. Chan, J. D. E. Creighton, R. B. Mann

We analyze the relationship between quasilocal masses calculated for solutions of conformally related theories. We show that the ADM mass of a static, spherically symmetric solution is conformally invariant (up to a constant factor) only if the background action functional is conformally invariant. Thus, the requirement of conformal invariance places restric

Christian Rueede, Norbert Straumann

After a brief summary of the Newton-Cartan theory in a form which emphasizes its close analogy to general relativity, we illustrate the theory with selective applications in cosmology. The geometrical formulation of this nonrelativistic theory of gravity, pioneered by Cartan and further developed by various workers, leads to a conceptually sound basis of New

V. M. Khatsymovsky

The Hilbert-Palatini (HP) Lagrangian of general relativity being written in terms of selfdual and antiselfdual variables contains Ashtekar Lagrangian (which governs the dynamics of the selfdual sector of the theory on condition that the dynamics of antiselfdual sector is not fixed). We show that nonequivalence of the Ashtekar and HP quantum theories is due t

Bhargavi Srinivasan, S. Ramasesha, H. R. Krishnamurthy

The $C_{60}$ molecule and its fragments are studied using Configuration Interaction (CI) and Variational Monte Carlo (VMC) techniques, within the Hubbard model. Using benzene as a test case, we compare the results of the approximate calculations with exact calculations. The fragments of $C_{60}$ studied are pyracylene, fluoranthene and corannulene. The energ

Francisco Dominguez-Adame

We consider exciton optical absorption in quasiperiodic lattices, focusing our attention on the Fibonacci case as typical example. The absorption spectrum is evaluated by solving numerically the equation of motion of the Frenkel-exciton problem on the lattice, in which on-site energies take on two values according to the Fibonacci sequence. We find that the

Klaus Ziegler, Matthias H. Hettler, Peter J. Hirschfeld

It has been known for some time that, in three dimensions, arbitrarily weak disorder in unconventional superconductors with line nodes gives rise to a nonzero residual density of zero-energy quasiparticle states N(0), leading to characteristic low-temperature thermodynamic properties similar to those observed in cuprate and heavy-fermion systems. In a strict

Bhargavi Srinivasan, S. Ramasesha, H. R. Krishnamurthy

We develop a novel multi-configurational Symmetrized Projector Quantum Monte Carlo (MSPQMC) method to calculate excited state properties of Hubbard models. We compare the MSPQMC results for finite Hubbard chains with exact results (where available) or with Density Matrix Renormalization Group (DMRG) results for longer chains. The energies and correlation fun

Kirill N. Alekseev, Gennady P. Berman, David K. Campbell, Ethan H. Cannon

We consider the motion of ballistic electrons in a miniband of a semiconductor superlattice (SSL) under the influence of an external, time-periodic electric field. We use the semi-classical balance-equation approach which incorporates elastic and inelastic scattering (as dissipation) and the self-consistent field generated by the electron motion. The couplin

Seungoh Ryu, A. Kapitulnik, S. Doniach

We show that the flux line lattice in a model layered HTSC becomes unstable above a critical magnetic field with respect to a plastic deformation via penetration of pairs of point-like disclination defects. The instability is characterized by the competition between the elastic and the pinning energies and is essentially assisted by softening of the lattice

J. W. Lynn, R. W. Erwin, J. A. Borchers, Q. Huang

Neutron scattering has been used to study the magnetic correlations and long wavelength spin dynamics of La1-xCaxMnO3 in the ferromagnetic regime (0<=x<1/2). For x=1/3 (Tc=250K) where the magnetoresistance effects are largest the system behaves as an ideal isotropic ferromagnet at low T, with a gapless (<0.04meV) dispersion relation E=Dq^2 and D(T=0)~170 meV

V. Cataudella, G. Franzese, M. Nicodemi, A. Scala

A general scheme for devising efficient cluster dynamics proposed in a previous letter [Phys.Rev.Lett. 72, 1541 (1994)] is extensively discussed. In particular the strong connection among equilibrium properties of clusters and dynamic properties as the correlation time for magnetization is emphasized. The general scheme is applied to a number of frustrated s

J. M. Prats, F. Lopez-Aguilar

Using unitary transformations, we express the Kondo lattice Hamiltonian in terms of fermionic operators that annihilate the ground state of the interacting system and that represent the best possible approximations to the actual charged excitations. In this way, we obtain an effective Hamiltonian which, for small couplings, consists in a kinetic term for con

Giorgio Parisi, Juan J. Ruiz-Lorenzo

We rederive the finite size scaling formula for the apparent critical temperature by using Mean Field Theory for the Ising Model above the upper critical dimension. We have also performed numerical simulations in five dimensions and our numerical data are in a good agreement with the Mean Field theoretical predictions, in particular, with the finite size exp

Beryl Hoffman

In this paper, I discuss machine translation of English text into Turkish, a relatively ``free&#39;&#39; word order language. I present algorithms that determine the topic and the focus of each target sentence (using salience (Centering Theory), old vs. new information, and contrastiveness in the discourse model) in order to generate the contextually appropr

Guido Minnen

Off-line compilation of logic grammars using Magic allows an incorporation of filtering into the logic underlying the grammar. The explicit definite clause characterization of filtering resulting from Magic compilation allows processor independent and logically clean optimizations of dynamic bottom-up processing with respect to goal-directedness. Two filter

F. Bonetto, G. Gallavotti, P. L. Garrido

The chaotic hypothesis discussed in [GC1] is tested experimentally in a simple conduction model. Besides a confirmation of the hypothesis predictions the results suggest the validity of the hypothesis in the much wider context in which, as the forcing strength grows, the attractor ceases to be an Anosov system and becomes an Axiom A attractor. A first test o

Tatsuo Shibata, Kunihiko Kaneko

Collective behavior is studied in globally coupled maps with distributed nonlinearity. It is shown that the heterogeneity enhances regularity in the collective dynamics. Low-dimensional quasiperiodic motion is often found for the mean-field, even if each element shows chaotic dynamics. The mechanism of this order is due to the formation of an internal bifurc

Ya. M. Shnir

The electric dipole moment of the hydrogen-like atom induced by a monopole moving outside the electron shell is calculated. The correction to the energy of the ground state of the hydrogen atom due to this interaction is calculated.

C. Alcock, R. A. Allsman, D. Alves, T. S. Axelrod

The MACHO project has been monitoring about ten million stars in the Large Magellanic Cloud in the search for gravitational microlensing events caused by massive compact halo objects (Machos) in the halo of the Milky Way. In our standard analysis, we have searched this data set for well sampled, long duration microlensing lightcurves, detected several microl

David H. Weinberg, Lars Hernquist, Neal Katz

Using cosmological simulations that incorporate gas dynamics and gravitational forces, we investigate the influence of photoionization by a UV radiation background on the formation of galaxies. In our highest resolution simulations, we find that photoionization has essentially no effect on the baryonic mass function of galaxies at $z=2$, down to our resoluti

Soojong Pak, D. T. Jaffe, L. D. Keller

We have mapped the H_2 v=1-0 S(1) (λ=2.1215 \micron) emission line along a 400 pc long strip and in a 50 pc region in the Galactic center. There is H_2 emission throughout the surveyed region. The typical de-reddened (A_K = 2.5 mag) surface brightness, about 3 X 10^{-5} ergs/s/cm^2/sr, is similar to the surface brightness in large-scale photon-dominated regi

Soojong Pak, D. T. Jaffe, L. D. Keller

We have observed near-IR H$_2$ line emission on large scales in the Galactic center. Paper I discussed our 400 pc long strip map and 50 pc map of the H_2 v=1-0 S(1) line. In this paper, we present observations of the higher vibrational lines, H_2 v=2-1 S(1) and v=3-2 S(3), at selected positions and conclude that strong far--UV radiations excites the H_2. We

Andrei F. Illarionov, Julian H. Krolik

It is generally supposed that when the &#34;compactness&#34; $l \equiv Lσ_T/(r m_e c^3)$ in photons above the pair-production threshold is large, few $γ$-rays can escape. We demonstrate that even when $l \gg 1$, if the high energy and low energy photons are produced in geometrically-separated regions, many of the $γ$-rays can, in fact, escape. Pair-productio

D. Montes, J. Sanz-Forcada, M. J. Fernández-Figueroa, R. Lorente

We present simultaneous H$α$, Na~{\sc i} D$_{1}$, D$_{2}$, and He~{\sc i} D$_{3}$ spectroscopic observations on the RS CVn system UX Ari. We have found a dramatic increase in the excess H$α$ emission equivalent width by a factor of 2 in an interval of 1 day that indicates the beginning of a strong flare in this system. The presence of the He~{\sc i} D$_{3}$

J. Mohr, M. Geller, D. Fabricant, G. Wegner

We analyze the galaxy population and dynamics of the galaxy cluster Abell 576 using 281 redshifts (230 new), R band CCD galaxy photometry over a 2h^{-1} Mpc by 2h^{-1} Mpc region centered on the cluster, an Einstein IPC image, and an Einstein MPC spectrum. The cluster galaxies with emission lines in their spectra have a larger velocity dispersion and are sig

Dan Abramovich

We prove the following theorem: Fibered Power Theorem: Let $X\rar B$ be a smooth family of positive dimensional varieties of general type, with $B$ irreducible. Then there exists an integer $n>0$, a positive dimensional variety of general type $W_n$, and a dominant rational map $X^n_B \das W_n$.

A. H. Bougourzi, M. Couture, M. Kacir

We derive the exact contribution of two spinons to the dynamical correlation function of the spin-1/2 Heisenberg model. For this, we use the isotropic limits of the exact form factors that have been recently computed through the quantum affine symmetry of the anisotropic Heisenberg model $XXZ$

A M Semikhatov, I Yu Tipunin

We give general expressions for singular vectors of the N=2 superconformal algebra in the form of {\it monomials} in the continued operators by which the universal enveloping algebra of N=2 is extended. We then show how the algebraic relations satisfied by the continued operators can be used to transform the monomials into the standard Verma-module expressio

A. H. Bougourzi, L. Vinet

We show how the states constructed from the action of the modes of bosonized vertex operators, that intertwine $U_q(\widehat{sl(2)})$ modules, are related to $q$-zonal functions.

A. H. Bougourzi

It is well known that the bosonized version of the Wakimoto construction allows the explicit realization of any affine algebra $\widehat{g}$, with arbitrary level $k$ in the homogeneous gradation, in terms of $dim(g)$ free bosonic fields. In this paper, we show in the case of the simplest affine algebra $\widehat{sl(2)}$, that the bosonized Wakimoto realizat

Francesco Mauri, Steven G. Louie

We present an {\it ab initio} approach for the computation of the magnetic susceptibility $χ$ of insulators. The approach is applied to compute $χ$ in diamond and in solid neon using density functional theory in the local density approximation, obtaining good agreement with experimental data. In solid neon, we predict an observable dependence of $χ$ upon pre

G. W. Gibbons, D. A. Rasheed

It has been argued by Dyson in the context of QED in flat spacetime that perturbative expansions in powers of the electric charge e cannot be convergent because if e is purely imaginary then the vacuum should be unstable to the production of charged pairs. We investigate the spontaneous production of such Dyson pairs in electrodynamics coupled to gravity. Th

O. Kechkin, M. Yurova

The Kramer--Neugebauer--like transformation is constructed for the stationary axisymmetric D=4 Einstein--Maxwell--dilaton--axion system. This transformation directly maps the dualized sigma--model equations of the theory into the nondualized ones. Also the new chiral $4 \times 4$ matrix representation of the problem is presented.

Sergei Skorik

We study different aspects of integrable boundary quantum field theories, focusing mostly on the ``boundary sine-Gordon model&#39;&#39; and its applications to condensed matter physics. The first part of the review deals with formal problems. We analyze the classical limit and perform semi-classical quantization. We show that the non-relativistic limit corre

J. Nemchik, N. N. Nikolaev, E. Predazzi, B. G. Zakharov

We present the first evaluation of color dipole cross section from experimental data on diffractive photo- and electroproduction of vector mesons. The dipole-size and energy dependence of the found dipole cross section is consistent with expectations from the BFKL dynamics.

Hooman Davoudiasl

We study the decay $D^0\rightarrow \bar K^{*0} π^- e^+ ν_e$, using $SU(2)_L \otimes SU(2)_R$ chiral perturbation theory for heavy charmed mesons and vector mesons, in the kinematic regime where $p_M \cdot p_π/m_M$ (here $M = D^0$ or $\bar K^{*0}$) is much smaller than the chiral symmetry breaking scale, $Λ_{χSB}$ ( $Λ_{χSB} \sim $ 1 GeV). We present the lead

Tobias Brandes, Arisato Kawabata

We investigate the influence of electron-phonon interactions on the DC-conductance $Γ$ of a quantum wire in the limit of one occupied subband. At zero temperature, a Tomonaga-Luttinger-like renormalization of $Γ$ to a value slightly larger than $2e^{2}/h$ is calculated for a realistic quantum wire model.

Rebecca Bruce, Janyce Wiebe, Ted Pedersen

This paper describes measures for evaluating the three determinants of how well a probabilistic classifier performs on a given test set. These determinants are the appropriateness, for the test set, of the results of (1) feature selection, (2) formulation of the parametric form of the model, and (3) parameter estimation. These are part of any model formulati

John P. Blakeslee, John L. Tonry

We present the $V$-band globular cluster luminosity functions (GCLFs) of the Fornax Cluster galaxies NGC 1344, NGC 1380, NGC 1399, and NGC 1404. Our observations reach to $V = 24.8$, roughly one magnitude beyond the GCLF turnover $m^0_V$, with $\sim90\%$ completeness. From the amplitude of the galaxy surface brightness fluctuations, we also estimate the numb

Stephen A. Shectman, Stephen D. Landy, Augustus Oemler, Douglas L. Tucker

The Las Campanas Redshift Survey (LCRS) consists of 26418 redshifts of galaxies selected from a CCD-based catalog obtained in the $R$ band. The survey covers over 700 square degrees in 6 strips, each 1.5$\arcdeg$ x 80$\arcdeg$, three each in the North and South galactic caps. The median redshift in the survey is about 30000 km~s$^{-1}$. Essential features of

Wayne Hu, Naoshi Sugiyama, Joseph Silk

Cosmic microwave background anisotropies provide a vast amount of cosmological information. Their full physical content and detailed structure can be understood in a simple and intuitive fashion through a systematic investigation of the individual mechanisms for anisotropy formation.

D. A. Baiko, D. G. Yakovlev

Thermal and electric conductivities of relativistic degenerate electrons are calculated for the case when electrons scatter by phonons in Coulomb crystals made of spherical finite--size nuclei at densities $10^{11}$~g/cm$^3 < ρ< 10^{14}$~g/cm$^3$, corresponding to the inner crust of a neutron star. In combination with the results of the previous article (for

D. A. Baiko, D. G. Yakovlev

Thermal and electric conductivities are calculated for degenerate electrons scattered by phonons in a crystal made of atomic nuclei. The exact phonon spectrum and the Debye--Waller factor are taken into account. Monte Carlo calculations are performed for body-centered cubic (bcc) crystals made of C, O, Ne, Mg, Si, S, Ca, and Fe nuclei in the density range fr

R. Pandharipande

Let M_{P^k}(P^r, d) be the moduli space of unparameterized maps μ:P^k -> P^r satisfying μ^*(O(1))= O(d). M_{P^k}(P^r,d) is a quasi-projective variety, and, in case k=1, M_{P^1}(P^r,d) is the fundamental open cell of Kontsevich&#39;s space of stable maps \bar{M}_{0,0}(P^r,d). It is shown that the Q-coefficient Chow ring of M_{P^k}(P^r,d) is canonically isomor

R. Pandharipande

Let \bar{M}_{0,n} be the moduli space of pointed, genus 0 curves. Let L_i denote the line bundle on \bar{M}_{0,n} associated to the i-th marked point (the fiber of L_i is the cotangent space of the pointed curve at the i-th point). Y_n=h^0(\bar{M}_{0,n}, L_1^{x_1} \tensor... \tensor L_n^{x_n}) is a symmetric function of the variables x_1,... x_n. Let R be th

Masato Kimura, Motohico Mulase

A classification of commutative integral domains consisting of ordinary differential operators with matrix coefficients is established in terms of morphisms between algebraic curves.

Lars Ernström, Gary Kennedy

We derive recursive equations for the characteristic numbers of rational nodal plane curves with at most one cusp, subject to point conditions, tangent conditions and flag conditions, developing techniques akin to quantum cohomology on a moduli space of stable lifts.

A. Yu. Alekseev, L. D. Faddeev, J. Fröhlich, V. Schomerus

Lattice current algebras were introduced as a regularization of the left- and right moving degrees of freedom in the WZNW model. They provide examples of lattice theories with a local quantum symmetry $U_q(\sg)$. Their representation theory is studied in detail. In particular, we construct all irreducible representations along with a lattice analogue of the

A. Strumia

The MSSM potential can have unphysical minima deeper than the physically acceptable one. We point out that their presence is quite generic in SO(10) unification with supergravity mediated soft terms. However, at least for moderate values of tanβ, the physically acceptable vacuum has a life-time longer than the universe age. Furthermore, by discussing the evo

Xiao-Song Lin

This an article about some elementary geometric and combinatorial natures of various knot energies. A related &#34;new&#34; knot invariant -- the X-crossing number -- is introduced.

S. E. Derkachov, A. N. Manashov

The results of analysis of the one--loop spectrum of anomalous dimensions of composite operators in the scalar $ ϕ^{4} $ model are presented. We give the rigorous constructive proof of the hypothesis on the hierarchical structure of the spectrum of anomalous dimensions -- the naive sum of any two anomalous dimensions generates a limit point in the spectrum.

P. Fiziev, H. Kleinert

We present a derivation of the Schrödinger equation for a path integral of a point particle in a space with curvature and torsion which is considerably shorter and more elegant than what is commonly found in the literature.

John H. Schwarz

A free superstring with chiral N=2 supersymmetry in six dimensions is proposed. It couples to a two-form gauge field with a self-dual field strength. Compactification to four dimensions on a two-torus gives a strongly coupled N=4 four-dimensional gauge theory with SL(2, Z) duality and an infinite tower of dyons. Various authors have suggested that this strin

G. L. Fogli, E. Lisi

We compare the effectiveness of various tests of three-flavor mixing in future long-baseline neutrino oscillation experiments. We analyze a representative case of mixing in a simplified three-flavor scheme, whose relevant parameters are one neutrino mass-square difference, $m^2$, and two mixing angles, $ψ$ and $ϕ$. We show that an unambiguous determination o

L. H. Ford, N. F. Svaiter

A model of a fluctuating lightcone due to a bath of gravitons is further investigated. The flight times of photons between a source and a detector may be either longer or shorter than the light propagation time in the background classical spacetime, and will form a Gaussian distribution centered around the classical flight time. However, a pair of photons em

D. V. Khveshchenko

We perform a semiclassical calculation of the magnetoresistance of spinless two-dimensional fermions in a long-range correlated random magnetic field. In the regime relevant for the problem of the half filled Landau level the perturbative Born approximation fails and we develop a new method of solving the Boltzmann equation beyond the relaxation time approxi

D. A. Moffett, T. H. Hankins

Previously unseen profile components of the Crab pulsar have been discovered in a study of the frequency-dependent behavior of its average pulse profile between 0.33 and 8.4 GHz. One new component, 36 degrees ahead of the main pulse at 1.4 GHz, is not coincident with the position of the precursor at lower frequencies. Two additional, flat-spectrum components

A. Dobado, J. R. Pelaez

Based on a dispersive approach, we apply the inverse amplitude method to unitarize one-loop SU(2) and SU(3) Chiral Perturbation Theory. Numerically, we find that this unitarization technique yields the correct complex analytic structure in terms of cuts and poles. Indeed, using the chiral parameter estimates obtained from low energy experiments we obtain the

Ka Lok Ng, Kin-Wang Ng

We compute numerically the scalar- and tensor-mode induced Stokes parameters of the cosmic microwave background, by taking into account the basis rotation effects. It is found that the tensor contribution to the polarization power spectrum get enhanced and dominates over the scalar contribution for low multipoles in a universe with or without recombination.

M. M. Kapranov

Let X be a smooth projectibe curve over a finite field. We consider the Hall algebra H whose basis is formed by isomorphism classes of coherent sheaves on X and whose typical structure constant is the number of subsheaves in a given sheaf belonging to a given isomorphism class and with given isomorphism class of quotient. We study this algebra in detail. It

Klaus Behrndt, Eric Bergshoeff, Bert Janssen

We show how, via $T$-duality, intersecting $D$-Brane configurations in ten (six) dimensions can be obtained from the elementary $D$-Brane configurations by embedding a Type IIB $D$-Brane into a Type IIB Nine-Brane (Five-Brane) and give a classification of such configurations. We show that only a very specific subclass of these configurations can be realized

Bas V. de Bakker, Jan Smit

In the dynamical triangulation model of four dimensional euclidean quantum gravity we investigate gravitational binding. Two scalar test particles (quenched approximation) have a positive binding energy, thereby showing that the model can represent gravitational attraction.

A. Cabo, A. Correa, R. Guevara, C. Rodriguez

Dispersion relations and polarizations for surface waves in infinite planar samples in the QHE regime are explicitly determined in the small wavevector limit in which the dielectric tensor can be considered as local. The wavelength and frequency regions of applicability of the results extends to the infrared region for typical experimental conditions. Then,

O. F. Dayi

The interactions which preserve the structure of the gauge interactions of the free theory are introduced in terms of the generalized fields method of solving the Batalin-Vilkovisky master equation. It is shown that by virtue of this method the solution of the descent equations resulting from the cohomological analysis is provided straightforwardly. The gene

Takeo Kato, Masatoshi Imada

Macroscopic quantum tunneling (MQT) for a single fluxon moving along a long Josephson junction is studied theoretically. To introduce a fluxon-pinning force, we consider inhomogeneities made by modifying thickness of an insulating layer locally. Two different situations are studied: one is the quantum tunneling from a metastable state caused by a single inho

I. R. Klebanov, A. A. Tseytlin

We present two 1/8 supersymmetric intersecting p-brane solutions of 11-dimensional supergravity which upon compactification to four dimensions reduce to extremal dyonic black holes with finite area of horizon. The first solution is a configuration of three intersecting 5-branes with an extra momentum flow along the common string. The second describes a syste

Emanuel Knill, Raymond Laflamme

Quantum Error Correction will be necessary for preserving coherent states against noise and other unwanted interactions in quantum computation and communication. We develop a general theory of quantum error correction based on encoding states into larger Hilbert spaces subject to known interactions. We obtain necessary and sufficient conditions for the perfe

John R. Klauder

A careful reexamination of the quantization of systems with first- and second-class constraints from the point of view of coherent-state phase-space path integration reveals several significant distinctions from more conventional treatments. Most significantly, we emphasize the importance of using path-integral measures for Lagrange multipliers which ensure

John R. Klauder

The metric known to be relevant for standard quantization procedures receives a natural interpretation and its explicit use simultaneously gives both physical and mathematical meaning to a (coherent-state) phase-space path integral, and at the same time establishes a fully satisfactory, geometric procedure of quantization.

M. A. Olshanetsky, V-B. K. Rogov

The $q$ analog of Modified Bessel functions and Bessel-Macdonald functions, were defined in our previous work (q-alg/950913) as general solutions of a second order difference equations. Here we present a collection of their representations by the Jackson q-integral.

Yuemin Sun, Efthimios Kaxiras

We conisder the brittle versus ductile behavior of aluminum in the framework of the Peierls-model analysis of dislocation emission from a crack tip. To this end, we perform first-principles quantum mechanical calculations for the unstable stacking energy $γ_{us}$ of aluminum along the Shockley partial slip route. Our calculations are based on density functio

Yu-min Juan, Efthimios Kaxiras

The generalized stacking fault (GSF) energy surfaces have received considerable attention due to their close relation to the mechanical properties of solids. We present a detailed study of the GSF energy surfaces of silicon within the framework of density functional theory. We have calculated the GSF energy surfaces for the shuffle and glide set of the (111)

Jun-Muk Hwang, Ngaiming Mok

We study deformations of irreducible Hermitian symmetric spaces $S$ of the compact type, known to be locally rigid, as projective-algberaic manifolds and prove that no jump of complex structures can occur. For each $S$ of rank $\ge 2$ there is an associated reductive linear group $G$ such that $S$ admits a holomorphic $G$-structure, corresponding to a reduct

Hiroyuki Takata

We consider 4D quantum-dilaton gravity with the most general coupling in a homogeneous and isotropic universe, especially an inflationary one, which is essentially characterized by an exponentially expanding scale factor with time. We show that on the inflationary background this theory can be miraculously renormalized, at least at the one-loop level, which

Lionel Carminati, Bruno Iochum, Thomas Schucker

Noncommutative geometry applied to the standard model of electroweak and strong interactions was shown to produce fuzzy relations among masses and gauge couplings. We refine these relations and show then that they are exhaustive.

R. N. Mohapatra

We discuss the predictions for neutron-anti-neutron oscillation in various supersymmetric and non-supersymmetric grand unified theories. It is pointed out that in a new class of superstring inspired grand unified theories of $E_6$-type that satisfy gauge coupling unification, breakdown of B-L symmetry occurs at an intermediate scale leading in turn to $\Delt

B. C. Allanach, S. F. King

In the context of the minimal supersymmetric standard model (MSSM), we discuss the introduction of exotic matter below the string scale $M_X$ in order to achieve gauge unification at $M_X$ (a constraint of a large class of string models). The possible types of exotic matter that can realise this are investigated and its effect on the top quark mass $m_t$ is

Matthias Neubert

We review the status of the theory and phenomenology of heavy-quark symmetry, exclusive weak decays of $B$ mesons, inclusive decay rates and lifetimes of $b$ hadrons, and CP violation in $B$-meson decays.

Yu. S. Kalashnikova, A. V. Nefediev

The QCD-motivated constituent string model is extended to consider the baryon. The system of three quarks propagating in the confining background field is studied in the Wilson loop approach, and the effective action is obtained. The resulting Lagrangian at large interquark distances corresponds to the Mercedes Benz string configuration. Assuming the quarks

V. A. Khoze, S. Lupia, W. Ochs

The recent data from LEP-1.5 on charged particle spectra are analyzed within the analytical QCD approach.

George Wei-Shu Hou

We discuss the possibility and likelihood that one may observe {\it like sign} top quark pair production at the Linear Collider. In general two Higgs models, flavor changing couplings involving top quark could be quite sizable. Exotic neutral Higgs bosons may decay dominantly via $t\bar c$ or $\bar tc$ channels. At the linear collider, $e^+e^- \to h^0A^0$ or

George Wei-Shu Hou

We investigate the $R_b$--$R_c$ problem, starting from the more diffcult $R_c$. Introducing an isosinglet charge 2/3 quark $Q$ moves both $R_c$ and $R_b$ in the right direction. If one allows for large $c$-$Q$ {\it and} $t$-$Q$ mixings, then $R_c$ could be reduced because of singlet content of charm quark, while $R_b$ gets enhanced by a light effective top q

Robert H. Brandenberger, Ariel R. Zhitnitsky

We discuss a cosmological scenario in which inflation is driven by a potential which is motivated by an effective Lagrangian approach to gravity. We exploit the recent arguments \cite{ARZ} that an effective Lagrangian $L_{eff}$ which, by definition, contains operators of arbitrary dimensionality is in general not a convergent but rather an asymptotic series

G. Raso

The high hadronic event statistics collected at the Z energy (LEP I) allowed a good understanding of the QCD dynamics. The coupling constant $α_s$ has been measured with several methods giving a global average $α_s(M_Z) = 0.122 \pm 0.004$. The flavour independence of $α_s$ has been tested obtaining $α_s^b/α_s^{udsc} = 0.997 \pm 0.023$. Quark-gluon jet differ

Gary Horowitz

I review some recent work in which the quantum states of string theory which are associated with certain black holes have been identified and counted. For large black holes, the number of states turns out to be precisely the exponential of the Bekenstein-Hawking entropy. This provides a statistical origin for black hole thermodynamics in the context of a pot

R. Lehoucq, M. Lachieze-Rey, J. P. Luminet

We assume that the Universe has a non trivial topology whose compact spatial sections have a volume significantly smaller than the horizon volume. By a topological lens effect, such a &#34;folded&#34; space configuration generates multiple images of cosmic sources, e.g. clusters of galaxies. We present a simple and powerful method to unveil non ambiguous obs

Zarko Bizaca, John Etnyre

We use Furuta&#39;s result, usually referred to as ``10/8-conjecture&#39;&#39;, to show that for any compact 3-manifold $M$ the open manifold $M\times\r$ has infinitely many different smooth structures. Another consequence of Furuta&#39;s result is existence of infinitely many smooth structures on open topological 4-manifolds with a topologically collarable

Alexander D. Mirlin, Yan V. Fyodorov, Frank-Michael Dittes, Javier Quezada

We study statistical properties of the ensemble of large $N\times N$ random matrices whose entries $ H_{ij}$ decrease in a power-law fashion $H_{ij}\sim|i-j|^{-α}$. Mapping the problem onto a nonlinear $σ-$model with non-local interaction, we find a transition from localized to extended states at $α=1$. At this critical value of $α$ the system exhibits multi

Tota Nakamura, Satoshi Takada

We clarify an instability of the ground state of the $Δ$ chain against the lattice distortion that increases a strength $(λ)$ of a bond in each triangle. It relaxes the frustration and causes a remarkable gap enhancement; only a $6\%$ increase of $λ$ causes the gap doubled from the fully-frustrated case $(λ=1)$. The lowest excitation is revealed to be a kink

Manny Rayner, David Carter

We show how a general grammar may be automatically adapted for fast parsing of utterances from a specific domain by means of constituent pruning and grammar specialization based on explanation-based learning. These methods together give an order of magnitude increase in speed, and the coverage loss entailed by grammar specialization is reduced to approximate