March 1994 arXiv papers — page 4

C. Holzhey, F. Larsen, F. Wilczek

In statistical physics, useful notions of entropy are defined with respect to some coarse graining procedure over a microscopic model. Here we consider some special problems that arise when the microscopic model is taken to be relativistic quantum field theory. These problems are associated with the existence of an infinite number of degrees of freedom per u

Hideaki Aoyama

Behavior of the Euclidean path integral at large orders of the perturbation series is studied. When the model allows tunneling, the path-integral functional in the zero instanton sector is known to be dominated by bounce-like configurations at large order of the perturbative series, which causes non-convergence of the series. We find that in addition to this

Nicolai Reshetikhin

An important property of a Hopf algebra is its quasitriangularity and it is useful various applications. This property is investigated for quantum groups $sl_2$ at roots of 1. It is shown that different forms of the quantum group $sl_2$ at roots of 1 are either quasitriangular or have similar structure which will be called autoquasitriangularity. In the most

Dongsu Bak, Oren Bergman

We perform a perturbative analysis of the nonabelian Aharonov-Bohm problem to one loop in a field theoretic framework, and show the necessity of contact interactions for renormalizability of perturbation theory. Moreover at critical values of the contact interaction strength the theory is finite and preserves classical conformal invariance.

Jin-Ho Cho, Seungjoon Hyun, Hyuk-Jae Lee

For the `classical' formulation of a massive spinning particle, the propagator is obtained along with the spin factor. We treat the system with two kinds of constraints that were recently shown to be concerned with the reparametrization invariance and `quasi-supersymmetry'. In the path integral, the BRST invariant Lagrangian is used and the same spin

G. Lazarides, C. Panagiotakopoulos

Sufficient conditions for the relation $tan β\simeq m_t/m_b$ to hold in supersymmetric grand unified theories are formulated. Essential ingredients are the $SU(2)_R$ gauge symmetry and a discrete matter parity. The applicability of our conditions is illustrated by specific examples. Implications for neutrino masses are discussed.

Alexei Yu. Smirnov, Zhijian Tao

Neutrino mass matrix generated by the Zee (radiative) mechanism has zero (in general, small) diagonal elements and a natural hierarchy of the nondiagonal elements. It can be considered as an alternative (with strong predictive power) to the matrices generated by the see-saw mechanism. The propagation in medium of the neutrinos with the Zee-mass matrix is stu

Marcelo Gleiser

The dynamics of weak vs. strong first order phase transitions is investigated numerically for 2+1 dimensional scalar field models. It is argued that the change from a weak to a strong transition is itself a (second order) phase transition, with the order parameter being the equilibrium fractional population difference between the two phases at the critical t

C. S. Kim, Daesung Hwang, Pyungwon Ko, Wuk Namgung

We calculate the so--called Fermi motion parameter $p_{_F}$ of ACCMM model using the variational method in a potential model approach. We also propose hadronic invariant mass distribution as an alternative experimental observable to measure $V_{ub}$ at future asymmetric $B$ factories.

H. Baer, M. Drees, C. Kao, M. Nojiri

We study the predictions of the simplest SU(5) grand unified model within the framework of minimal supergravity, including constraints from the radiative breaking of electroweak symmetry. As a consequence of the unification of the $b$-quark and $τ$-lepton Yukawa couplings, the top quark mass is predicted to be close to its fixed point value. We delineate the

A. M. Chaara, H. Kröger, L. Marleau, K. J. M. Moriarty

We study glueball and meson scattering in compact $QED_{2+1}$ gauge theory in a Hamiltonian formulation and on a momentum lattice. We compute ground state energy and mass, and introduce a compact lattice momentum operator for the computation of dispersion relations. Using a non-perturbative time-dependent method we compute scattering cross sections for glueb

M. Caselle, F. Gliozzi, S. Vinti

Within the framework of a quantum flux tube model for the interquark potential it is possible to predict that in (2+1) dimensions the space-like string tension must increase with the temperature in the deconfined phase and that the thickness of the flux tube must coincide with the inverse of the deconfinement temperature. Both these predictions are in good a

David E. Brahm

We analyze the critical line of $λϕ^4_4$ perturbatively in the bare coupling $λ_0$, by setting the daisy-improved renormalized mass to zero. By comparing to lattice data, we can then quantify the relation between the continuum cutoff and the lattice spacing; for the 4-dimensional hypercubic lattice we find $(Λa)_{C4} = 4.893$. We perform a similar analysis f

Geoff Hayward

The classical value of the Hamiltonian for a system with timelike boundary has been interpreted as a quasilocal energy. This quasilocal energy is not positive definite. However, we derive a `quasilocal dominant energy condition' which is the natural consequence of the local dominant energy condition. We discuss some implications of this quasilocal energy

Abhay Ashtekar

This report is based on the talk given by the author in the concluding session of the workshop on Canonical Methods in Classical and Quantum General Relativity, held a Bad-Honef, Germany, in September 93. It contains an assessment of the canonical approach in general, an overview of recent developments within the canonical approach based on connections and l

P. 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 makes it impossible to interpret the Coleman Alpha parameters of the effective interactions as a quantum field on superspace, reducible to an infinite tower of fields on space-ti

I. G. Avramidi

We continue the development of the effective covariant methods for calculating the heat kernel and the one-loop effective action in quantum field theory and quantum gravity. The status of the low-energy approximation in quantum gauge theories and quantum gravity is discussed in detail on the basis of analyzing the local Schwinger - De Witt expansion. It is a

I. G. Avramidi

We use our recently proposed algebraic approach for calculating the heat kernel associated with the Laplace operator to calculate the one-loop effective action in the non-Abelian gauge theory. We consider the most general case of arbitrary space-time dimension, arbitrary compact simple gauge group and arbitrary matter and assume a covariantly constant gauge

Hans-Juergen Matschull

The Wilson loop functionals in terms of Ashtekar's variables were the first (formal) solutions to the quantized hamiltonian constraint of canonical gravity. Here it is shown that the same functionals also solve the supergravity constraints and some evidence is presented that they are artificially generated by multiplying the constraints by the metric det

Q. Niu

The response of particle density to a dilation of a periodic potential in an insulator, with or without a fixed background potential or a magnetic field, is shown to be quantized. A similar phenomenon occurs in a quantum Hall system, where the derivative of the electron density with respect to the magnetic field is quantized in units of $e/h$, the inverse fl

Jeffrey Yepez

Introduced is a lattice-gas with long-range 2-body interactions. An effective inter-particle force is mediated by momentum exchanges. There exists the possibility of having both attractive and repulsive interactions using finite impact parameter collisions. There also exists an interesting possibility of coupling these long-range interactions to a heat bath.

Yoshiaki SOFUE

We show that HI clouds in the Magellanic Clouds are stripped by the ram-pressure due to the halo and disk gases of the Galaxy. Molecular clouds are swept to the edge of the LMC, showing an eccentric distribution. The stripped HI clouds form a narrow band on the sky, and mimics the Magellanic Stream, when the LMC takes a polar orbit. We point out that the Mag

Robin Tuluie, Richard A. Matzner, Peter Anninos

We trace the evolution of cosmic microwave background photons propagating through a reionized model universe. The reionization of the intergalactic medium is achieved by UV photons emitted from the decaying `hot' dark matter neutrinos. The model universe is represented by a comoving cube through which we propagate photons and subject them to the Sachs-Wo

A. D. King, Charles H. Walter

Let $M$ be a complete nonsingular fine moduli space of modules over an algebra $S$. A set of conditions is given for the Chow ring of $M$ to be generated by the Chern classes of certain universal bundles occurring in a projective resolution of the universal $S$-module on $M$. This result is then applied to the varieties $G_T$ parametrizing homogeneous ideals

Jean Valles

We prove here the following results: \begin{th} Let $E$ a rank 2 vector bundle over ${\bf P}_3$, if $C$ is a reduced irreducible curve of ${\bf P}_3^{\vee}$ such that $E_H$ is unstable for all $H\in C$ then $C$ is a line. \end{th} We define now the set $W(E)$ as the set of planes $H$ such that the restricted bundle $E_H$ is unstable (that means non semi-stab

O. A. Soloviev

We discuss special perturbations of the gauged level $k$ WZNW model inspired by the $σ$-model perturbation of the nonunitary WZNW model. In the large $k$ limit there is a second conformal point in the vicinity of the ultarviolet fixed point. At the second critical point the conformal model has a rational Virasoro central charge which no longer corresponds to

Johannes Kellendonk

To a given tiling a non commutative space and the corresponding C*-algebra are constructed. This includes the definition of a topology on the groupoid induced by translations of the tiling. The algebra is also the algebra of observables for discrete models of one or many particle systems on the tiling or its periodic identification. Its scaled ordered K_0-gr

A. S. Yelkhovsky

The expression for the first recoil correction to the Dirac-Coulomb spectrum is obtained employing the gauge invariance.

Omar Foda, K. Iohara, M. Jimbo, R. Kedem

An elliptic deformation of $\widehat{sl}_2$ is proposed. Our presentation of the algebra is based on the relation $RLL=LLR^*$, where $R$ and $R^*$ are eight-vertex $R$-matrices with the elliptic moduli chosen differently. In the trigonometric limit, this algebra reduces to a quotient of that proposed by Reshetikhin and Semenov-Tian-Shansky. Conjectures conce

V. Bernard, N. Kaiser, Ulf-G. Meißner, A. Schmidt

We present an exploratory study of two pion photo-- and electroproduction off the nucleon in the threshold region. To calculate the pertinent amplitudes, we make use of heavy baryon chiral perturbation theory. We show that due to finite chiral loops the production cross section for final states with two neutral pions is considerably enhanced. The experimenta

A. Varchenko

The Knizhnik-Zamolodchikov equation associated with $s\ell_2$ is considered. The transition functions between asymptotic solutions to the Knizhnik-Zamolodchikov equation are described. A connection between asymptotic solutions and the crystal base in the tensor product of modules over the quantum group $U_qs\ell_2$ is established, in particular, a correspond

A. G. Bytsko

We consider O(3) sigma-model as a reduction of the principal chiral field. This approach allows to introduce the currents with ultralocal Poisson brackets and to obtain the zero-curvature equation which admits the fundamental Poisson bracket.

A. Hüffmann

The general structure of the representation theory of a $Z_2$-graded coalgebra is discussed. The result contains the structure of Fourier analysis on compact supergroups and quantisations thereof as a special case. The general linear supergroups serve as an explicit illustration and the simplest example is carried out in detail.

V. A. Fateev, V. A. Kazakov, P. B. Wiegmann

We present the exact and explicit solution of the principal chiral field in two dimensions for an infinitely large rank group manifold. The energy of the ground state is explicitly found for the external Noether's fields of an arbitrary magnitude. The exact Gell-Mann - Low function exhibits the asymptotic freedom behaviour at large value of the field in

Naohito Nakazawa, Eisaku Sakane

We apply Stochastic Quantization Method to dissipative systems at finite temperature. Especially, the relation of SQM to the Caldeira-Leggett model is clarified ensuring that the naive Wick rotation is improved in this context. We show that the Langevin system obtained by the \lq\lq Improved Wick Rotation " prescription is equivalent to an ideal friction

S. Hosono, A. Klemm, S. Theisen

We give an introduction to mirror symmetry of strings on Calabi-Yau manifolds with an emphasis on its applications e.g. for the computation of Yukawa couplings. We introduce all necessary concepts and tools such as the basics of toric geometry, resolution of singularities, construction of mirror pairs, Picard-Fuchs equations, etc. and illustrate all of this

Paul Langacker, Nir Polonsky

The SU(5) unification-scale relation h_b=h_tau between the b and tau Yukawa couplings severely constrains tan beta and m_t (even more so if h_t=h_b= h_tau holds) in supersymmetric models. We examine the implications of these constraints for the Higgs sector assuming universal soft breaking terms, and emphasize that both of these relations impose unique chara

R. Casalbuoni, P. Chiappetta, A. Deandrea, S. De Curtis

We consider the production of the lightest pseudo-Goldstone bosons at future colliders through the vector resonances predicted by the extended BESS model, which consists of an effective lagrangian parametrization with dynamical symmetry breaking, describing scalar, vector and axial-vector bound states in a rather general framework. We find that the detection

R. Escribano, E. Massó

The effective Lagrangian approach allows us to constrain fermion magnetic and electric moments using LEP-I data. We improve some of the previous limits on these moments.

Marek Pawlowski, Ryszard Raczka, SINS/SISSA

We call attention to the fact that the gauge symmetry $SU(3)\times SU(2)_{_L}\times U(1)$ of the Standard Model can be easily and naturally extended by the local conformal symmetry connected with the possibility of choosing the local length scale. Restricting the admissible interactions to the lowest order conformal invariant interactions one gets the unique

Barbara Mele

I review the present state of knowledge on lepton energy spectra in the inclusive semileptonic decay of beauty hadrons, as a means to measure b polarization effects on the Z peak. Charged-lepton as well as neutrino spectra are considered.

U. Kraemmer, A. K. Rebhan, H. Schulz

The gauge-boson sector of perturbative scalar electrodynamics is investigated in detail as a testing ground for resummation methods in hot gauge theories. It also serves as a simple non-trivial reference system for the non-Abelian gluon plasma. The complete next-to-leading order contributions to the polarization tensor are obtained within the resummation sch

Clifford M. WILL

Inspiralling binary systems of neutron stars or black holes are promising sources of gravitational radiation detectable by large-scale laser interferometric gravitational observatories, such as the US LIGO and Italian-French VIRGO projects. Accurate theoretical gravitational-waveform templates will be needed to carry out matched filtering data analysis of th

R. Fehrenbacher, M. R. Norman

We contrast the effects of non-magnetic impurities on the properties of superconductors having a \dw\ order parameter, and a highly anisotropic s-wave (ASW) gap with the same nodal structure. The non-vanishing, impurity induced, off-diagonal self-energy in the ASW state is shown to gap out the low energy excitations present in the clean system, leading to a

Shoudan Liang, Hanbin Pang

In order to extend the density-matrix renormalization-group (DMRG) method to two-dimensional systems, we formulate two alternative methods to prepare the initial states. We find that the number of states that is needed for accurate energy calculations grows exponentially with the linear system size. We also analyze how the states kept in the DMRG method mana

N. K. Allsopp, C. J. Lambert

We highlight a new "transverse" interference effect, arising from the coupling between electrons and holes, induced by a superconducting island in contact with a normal metal. As an example we compute the electrical conductance G of a T-shaped mesoscopic sample, formed by joining a horizontal bar of normal metal to a vertical leg of the same material

P. Tarazona, E. Chacon, J. P. Hernandez

We report the first theoretical model for the alkali fluids which yields a liquid-vapor phase coexistence with the experimentally observed features and electrical conductivity estimates which are also in accord with observations. We have carried out a Monte Carlo simulation for a lattice gas model which allows an integrated study of the structural, thermodyn

Vladimir E. Korepin, Anatoli G. Izergin, Fabian H. L. Essler, Denis B. Uglov

We consider a special correlation function in the isotropic spin-$\half$ Heisenberg antiferromagnet. It is the probability of finding a ferromagnetic string of (adjacent) spins in the antiferromagnetic ground state. We give two different representations for this correlation function. Both of them are exact at any distance, but one becomes more effective for

G. Sigl, D. N. Schramm, P. Bhattacharjee

In this paper we show that the conventional diffusive shock acceleration mechanism for cosmic rays associated with relativistic astrophysical shocks in active galactic nuclei (AGNs) has severe difficulties to explain the highest energy cosmic ray events. We show that protons above around $2\times10^{20}\eV$ could have marginally been produced by this mechani

Konrad Kuijken

We describe a method for parameterizing two-integral distribution functions, based on triangular tesselations of the integral plane. We apply the method to the axisymmetric isotropic rotator model for the Galactic bulge of Kent~(1992), and compare the results with observations of proper motions in Baade's Window, and with radial velocity surveys. In spit

P. Peter, D. Polarski, A. A. Starobinsky

We consider double-inflationary models with two noninteracting scalar fields, a light scalar field $ϕ_l$ with potential $\frac{1}{2}m_l^2ϕ_l^2$ and a heavy scalar field $ϕ_h$ with potential $\fracλ{n}ϕ_h^n$ with $n=2,4$. CDM with the initial spectrum of adiabatic perturbations produced in these models is compared with observations. These models contain two m

Albert A. Zijlstra, Peter A. M. van Hoof, Jessica M. Chapman, Cecile Loup

Radio continuum emission has been detected from a planetary nebula in the Large Magellanic Cloud: this is the first radio continuum detection for any planetary nebula outside our galaxy. The radio flux density is a factor of two lower than predicted from the \hbeta\ flux. This could be due either to a two-component morphology or to a stellar contribution to

Paolo Catelan, Lauro Moscardini

We discuss the non--linear growth of the kurtosis of the smoothed peculiar velocity field (along an arbitrary direction), in an Einstein--de Sitter universe, induced by Gaussian primordial density fluctuations. Applying the perturbative theory, we show that, for different cosmological models, a departure from the original Gaussian distribution is gravitation

Fumihiko Sugino, Osamu Tsuchiya

Motivated by understanding the phase structure of $d >1$ strings we investigate the $c=1$ matrix model with $g' (\tr M(t)^{2})^{2}$ interaction which is the simplest approximation of the model expected to describe the critical phenomena of the large-$N$ reduced model of odd-dimensional matrix field theory. We find three distinct phases: (i) an ordinary $

Jose Gaite

We study the realization of conformal symmetry in the QHE as part of the $W_\infty$ algebra. Conformal symmetry can be realized already at the classical level and implies the complexification of coordinate space. Its quantum version is not unitary. Nevertheless, it can be rendered unitary by a suitable modification of its definition which amounts to taking p

E. Mendel, L. Polley

Recently it was suggested that the problem of species doubling with Kogut-Susskind lattice fermions entails, at finite chemical potential, a confusion of particles with antiparticles. What happens instead is that the familiar correspondence of positive-energy spinors to particles, and of negative-energy spinors to antiparticles, ceases to hold for the Kogut-

R. Graham

Spatially homogeneous cosmological models reduce to Hamiltonian systems in a low dimensional Minkowskian space moving on the total energy shell $H=0$. Close to the initial singularity some models (those of Bianchi type VIII and IX) can be reduced further, in a certain approximation, to a non-compact triangular billiard on a 2-dimensional space of constant ne

Hiroshi Kunitomo, Makoto Sakaguchi, Akira Tokura

It has been shown that there is a sequential embedding structure in a $w_N$\ string theory based on a linearized $W_N$\ algebra. The $w_N$\ string theory is obtained as a special realization of the $w_{N+1}$\ string. The $w_{\infty}$\ string theory is a universal string theory in this sense. We have also shown that there is a similar sequence for $N=1$\ stri

Heinz König

I present the contribution of gluinos and scalar quarks to the decay rate of the top quark into a charged Higgs boson and a bottom quark within the minimal supersymmetric standard model, including the mixing of the scalar partners of the left- and right-handed top quark. I show that for certain values of the supersymmetric parameters the standard QCD loop co

Barry M. McCoy

A four part series of lectures on the connection of statistical mechanics and quantum field theory. The general principles relating statistical mechanics and the path integral formulation of quantum field theory are presented in the first lecture. These principles are then illustrated in lecture 2 by a presentation of the theory of the Ising model for $H=0$,

H. -C. Jean, G. L. Payne, W. N. Polyzou

The method suggested by Balian and Brézin for treating angular momentum reduction in the Faddeev equations is shown to be applicable to the relativistic three-body problem.

M. Schlieker, Bruno Zumino

We show that the algebra of the bicovariant differential calculus on a quantum group can be understood as a projection of the cross product between a braided Hopf algebra and the quantum double of the quantum group. The resulting super-Hopf algebra can be reproduced by extending the exterior derivative to tensor products.

S. Anderegg, V. Mukhanov

We derive the first order canonical formulation of cosmological perturbation theory in a Universe filled by a few scalar fields. This theory is quantized via well-defined Hamiltonian path integral. The propagator which describes the evolution of the initial (for instance, vacuum) state, is calculated.

J. S. Apps

We obtain an expression for the curvature of the Lie group SDiff$\cal M$ and use it to derive Lukatskii's formula for the case where $\cal M$ is locally Euclidean. We discuss qualitatively some previous findings for SDiff$S^{2}$ in conjunction with our result.

P. Montague

We discuss questions arising from the work of Schellekens. After introducing the concept of complementary representations, we examine $Z_2$-orbifold constructions in general, and propose a technique for identifying the orbifold theory without knowledge of its explicit construction. This technique is then generalised to twists of order 3, 5 and 7, and we proc

Yuval Ne'eman

Inflationary Cosmology makes the universe ``eternal" and provides for recurrent universe creation, ad infinitum -- making it also plausible to assume that ``our" Big Bang was also preceeded by others, etc.. However, GR tells us that in the ``parent" universe's reference frame, the newborn universe's expansion will never start. Our picture

Zheng Huang, Mahiko Suzuki, Xin-Nian Wang

If a disoriented chiral condensate is created over an extended space-time region following a rapid cooling in hadronic or nuclear collisions, the misalignment of the condensate with the electroweak symmetry breaking can generate observable effects in the processes which involve both strong and electromagnetic interactions. We point out the relevance of the d

M. Consoli, P. M. Stevenson

The "triviality" of $(λΦ^4)_4$ quantum field theory means that the renormalized coupling $λ_R$ vanishes for infinite cutoff. That result inherently conflicts with the usual perturbative approach, which begins by postulating a non-zero, cutoff-independent $λ_R$. We show how a "trivial" solution $λ_R=0$ can be compatible with the known structur

Leandros Perivolaropoulos

The spinning vortex is a stationary generalization of the Nielsen-Olesen vortex involving a linear time dependence of the Goldstone boson. Here we show that this vortex can be embedded in models with $SU(2)_{global}\times U(1)_{local}$ symmetry. We also map the stability sector in parameter space and show that for sufficiently large spinning velocities the v

T. Moroi, T. Yanagida

We show that the Polonyi problem is solved in the minimum SUSY-GUT model in which a self-coupling strength for a heavy Higgs $Σ$, $λΣ^{3}$, is very small $λ\sim 10^{-6}$. It is stressed that with this small $λ$ the mass of the physical $Σ$ becomes $m_Σ \sim 10^{12}\GEV$ and the unification scale is raised up to the gravitational one, $M\simeq 2\times 10^{18}

the CLEO collaboration

We have fully reconstructed decays of both B0 and B- Mesons into final states containing either D, D*, D**, Psi, Psi', or Chi_{c1} mesons. This allows us to obtain new results on many physics topics including branching ratios, tests of the factorization hypothesis, color suppression, resonant substructure, and the B- - B0 mass difference.

S. Catterall, J. Kogut, R. Renken

We have studied a model which has been proposed as a regularisation for four dimensional quantum gravity. The partition function is constructed by performing a weighted sum over all triangulations of the four sphere. Using numerical simulation we find that the number of such triangulations containing $V$ simplices grows faster than exponentially with $V$. Th

G. P. Lepage

These lectures discuss field theoretic techniques that might allow for realistic simulations of lattice QCD on small computers.

Anton K. Rebhan, Dominik J. Schwarz

A closed set of equations for the evolution of linear perturbations of homogeneous, isotropic cosmological models can be obtained in various ways. The simplest approach is to assume a macroscopic equation of state, e.g.\ that of a perfect fluid. For a more refined description of the early universe, a microscopic treatment is required. The purpose of this pap

M. Gasperini, G. Veneziano

We consider the coupled evolution of density, (scalar) metric and dilaton perturbations in the transition from a ``stringy" phase of growing curvature and gravitational coupling to the standard radiation-dominated cosmology. We show that dilaton production, with a spectrum tilted towards large frequencies, emerges as a general property of this scenario.

D. Korotkin, H. Nicolai

We construct a new exact solution of Einstein's equations in vacuo in terms of Weyl canonical coordinates. This solution may be interpreted as a black hole in a space-time which is periodic in one direction and which behaves asymptotically like the Kasner solution with Kasner index equal to $4M L^{-1}$, where $L$ is the period and $M$ is the mass of the

Tin-Lun Ho

Electron tunneling between quantum Hall systems on the same two dimensional plane separated by a narrow barrier is studied. We show that in the limit where inelastic scattering time is much longer than the tunneling time, which can be achieved in practice, electrons can tunnel back and forth through the barrier continously, leading to an oscillating current

Tin-Lun Ho

It is pointed out recently that the $ν=1/m$ quantum Hall states in bilayer systems behave like easy plane quantum ferromagnets. We study the magnetotransport of these systems using their ``ferromagnetic" properties and a novel spin-charge relation of their excitations. The general transport is a combination of the ususal Hall transport and a time depende

D. Olguin, R. Baquero

We calculate the bulk- (infinite system), (100)-bulk-projected- and (100)-Surface-projected Green's functions using the Surface Green's Function Matching method (SGFM) and an empirical tight-binding hamiltonian with tight-binding parameters (TBP) that describe well the bulk band structure of CdTe. In particular, we analyze the band (B--4) arising at

G. Baskaran, D. G. Kanhere, Mihir Arjunwadkar, Rahul Basu

We present physical arguments as well as numerical evidence to show that the Cooper pair (gap) function vanishes on the Fermi surface in strongly correlated electron systems such as \tJ and \lU Hubbard models in one and two dimensions. Using exact diagonalization, we study a correlation function which is a measure of the gap function even in a finite system,

R. Buhleier, S. D. Brorson, I. E. Trofimov, J. O. White

We have measured the electrodynamic properties of Y_{1-x}Pr_xBa_2Cu_3O_7 single crystal thin films as a function of temperature using coherent THz-time-domain spectroscopy. We obtain directly the complex conductivity $σ=σ_1+iσ_2$, the London penetration depth $λ_L$, the plasma frequency $ω_p$, and the quasiparticle scattering rate $1/τ$. We find that $1/τ$ d

Guang-Ming Zhang, Lu Yu

We present an asymptotically exact solution of a local copper-oxide model abstracted from the multi-band models. The phase diagram is obtained through the renormalization-group analysis of the partition function. In the strong coupling regime, we find an exactly solved line, which crosses the quantum critical point of the mixed valence regime separating two

Jun Pan, Mushti V. Ramakrishna

A structural model for intermediate sized silicon clusters is proposed that is able to generate unique structures without any dangling bonds. This structural model consists of bulk-like core of five atoms surrounded by fullerene-like surface. Reconstruction of the ideal fullerene geometry results in the formation of crown atoms surrounded by $π$-bonded dimer

Steven W. Rick, J. D. Doll

The ground and excited vibrational states for the three hydrogen isotopes on the Pd(111) surface have been calculated. Notable features of these states are the high degree of anharmonicity, which is most prominently seen in the weak isotopic dependence of the parallel vibrational transition, and the narrow bandwidths of these states, which imply that atomic

P. A. Johnson, A. Mastichiadis, R. J. Protheroe, T. S. Stanev

We consider the emission of high energy to very high energy $γ$-rays in radio-quiet active galactic nuclei (AGN) or the central regions of radio-loud AGN. We use our results to estimate the $γ$-ray flux from the central regions of nearby AGN, and then to calculate the contribution to the diffuse $γ$-ray flux from unresolved AGN.

C. S. Aulakh, V. Soni

A class of explicit exact solutions of Einstein Yang Mills Chern Simons (EYMCS) theory corresponding to topological solitons carrying non-Abelian topological electric charge is obtained. This verifies a conjecture made in Ref.[1,2] regarding the stabilization of the corresponding charged configurations in the theory without gravity .

R. Kirschner, L. N. Lipatov, L. Szymanowski

We study the effective action describing high-energy scattering processes in the multi-Regge limit of QCD, which should provide the starting point for a new attempt to overcome the limitations of the leading logarithmic and the eikonal approximations. The action can be obtained via simple graphical rules or by integrating in the QCD functional integral over

A. Borisov

This is the major revision. The main purpose of this paper is to prove that minimal discrepancies of $n$-dimensional toric singularities can accumulate only from above and only to minimal discrepancies of toric singularities of dimension less than $n$. I also prove that some lower-dimensional minimal discrepancies do appear as such limit.

Oleg Andreev, Boris Feigin

We show how bosonic (free field) representations for so-called degenerate conformal theories are built by singular vectors in Verma modules. Based on this construction, general expressions of conformal blocks are proposed. As an example we describe new modules for the $SL(2)$ Wess-Zumino -Witten model. They are, in fact, the simplest non-trivial modules in a

Johan van de Leur

To every partition $n=n_1+n_2+\cdots+n_s$ one can associate a vertex operator realization of the Lie algebras $a_{\infty}$ and $\hat{gl}_n$. Using this construction we make reductions of the $s$--component KP hierarchy, reductions which are related to these partitions. In this way we obtain matrix KdV type equations. Now assuming that (1) $τ$ is a $τ$--funct

I. L. Shapiro

Quantum theory of conformal factor coupled with matter fields is investigated. The more simple case of the purely classical scalar matter is considered. It is calculated the conformal factor contribution to the effective potential of scalar field. Then the possibility of the first order phase transition is explored and the induced values of Newtonian and cos

Paul C. Eklof, Saharon Shelah

As a consequence of identifying the principle described in the title, we prove that for any uncountable cardinal lambda, if there is a lambda-free Whitehead group of cardinality lambda which is not free, then there are many ``nice'' Whitehead groups of cardinality lambda which are not free.

Saharon Shelah

Let T be the family of open subsets of a topological space (not necessarily Hausdorff or even T_0). We prove that if T has a base of cardinality <= mu, lambda <= mu < 2^lambda, lambda strong limit of cofinality aleph_0, then T has cardinality <= mu or >= 2^lambda. This is our main conclusion. First we prove it under some set theoretic assumption, which is cl

G. López, Francisco Marcellán, Walter Van Assche

We investigate the asymptotic properties of orthogonal polynomials for a class of inner products including the discrete Sobolev inner products $\langle h,g \rangle = \int hg\, dμ+ \sum_{j=1}^m \sum_{i=0}^{N_j} M_{j,i} h^{(i)}(c_j) g^{(i)}(c_j)$, where $μ$ is a certain type of complex measure on the real line, and $c_j$ are complex numbers in the complement o

M. A. Soloviev

We prove that the distributions defined on the Gelfand-Shilov spaces, and hence more singular than hyperfunctions, retain the angular localizability property. Specifically, they have uniquely determined support cones. This result enables one to develop a distribution-theoretic techniques suitable for the consistent treatment of quantum fields with arbitraril

M. Matone

Geodesic completness and self-adjointness imply that the Hamiltonian for anyons is the Laplacian with respect to the Weil-Petersson metric. This metric is complete on the Deligne-Mumford compactification of moduli (configuration) space. The structure of this compactification fixes the possible anyon configurations. This allows us to identify anyons with sing

Hiroshi Nohara

We perform the numerical simulation of the two dimensional chiral Gross Neveu model using the Kogut-Susskind(KS) fermion. In the case of SU(4), the Kosterlitz-Thouless phase transition happens at some critical value of the coupling constant. In the case of one flavour, there exists the strong coupling phase in which the correlation functions vanish and the g

Tatsu Takeuchi, Aaron K. Grant, Mihir P. Worah

We use the operator product expansion (OPE) to show that non-perturbative QCD corrections to $Δρ$ can be calculated using unsubtracted dispersion relations for either the transverse or the longitudinal vacuum polarization functions. Recent calculations of the non-perturbative contribution to $Δρ$ based on a non-relativistic calculation of corrections to the

T. Gousset, B. Pire

The difference between the timelike and spacelike meson form factors is analysed in the framework of perturbative QCD with Sudakov effects included. It is found that integrable singularities appear but that the asymptotic behavior is the same in the timelike and spacelike regions. The approach to asymptotia is quite slow and a rather constant enhancement of

Carsten Grosse-Knetter, Ingolf Kuss

We point out that the equivalence theorem, which relates the amplitude for a process with external longitudinally polarized vector bosons to the amplitude in which the longitudinal vector bosons are replaced by the corresponding pseudo-Goldstone bosons, is not valid for effective Lagrangians. However, a more general formulation of this theorem also holds for