June 1994 arXiv papers — page 7

K. F. Liu, S. J. Dong, Terrence Draper, Walter Wilcox

The $πNN$ form factor $g_{πNN}(q^2)$ is obtained from a quenched lattice QCD calculation of the pseudoscalar form factor $g_P(q^2)$ of the proton with pion pole dominance. We find that $g_{πNN}(q^2)$ fitted with the monopole form agrees well with the Goldberger-Treiman relation and is much preferred over the dipole form. The monopole mass is determined to be

W. Zhong, David Vanderbilt, K. M. Rabe

We develop a first-principles scheme to study ferroelectric phase transitions for perovskite compounds. We obtain an effective Hamiltonian which is fully specified by first-principles ultra-soft pseudopotential calculations. This approach is applied to BaTiO$_3$, and the resulting Hamiltonian is studied using Monte Carlo simulations. The calculated phase seq

E. R. Mucciolo, V. N. Prigodin, B. L. Altshuler

We study the statistics of level widths of a quantum dot with extended contacts in the absence of time-reversal symmetry. The widths are determined by the amplitude of the wavefunction averaged over the contact area. The distribution function of level widths for a two-point contact is evaluated exactly. The distribution resembles closely the result obtained

R. Michael Young, Johanna D. Moore

Research in discourse processing has identified two representational requirements for discourse planning systems. First, discourse plans must adequately represent the intentional structure of the utterances they produce in order to enable a computational discourse agent to respond effectively to communicative failures \cite{MooreParisCL}. Second, discourse p

Steven W. Rick, Steven J. Stuart, B. J. Berne

A new molecular dynamics model in which the point charges on atomic sites are allowed to fluctuate in response to the environment is developed and applied to water. The idea for treating charges as variables is based on the concept of electronegativity equalization according to which: (a) The electronegativity of an atomic site is dependent on the atom's

F. A. Rasio, S. L. Shapiro

We present a new numerical study of the equilibrium and stability properties of close binary systems using the smoothed-particle hydrodynamics (SPH) technique. We adopt a simple polytropic equation of state $p=Kρ^\gam$ with $\gam=5/3$ and $K=\,$constant within each star, applicable to low-mass degenerate dwarfs as well as low-mass main-sequence stars. Along

D. Syer, Cita

(To appear in the Astrophysical Journal) Holdom and Malaney (1994) have suggested a mechanism for gamma-ray bursts which requires that stars be captured by a neutrino ball. Neutrino balls would be, for the most part, denser than main sequence stars, but their density would decrease as their mass increased. We show that small neutrino balls would subject star

Salim Nasser, Neil Turok

The standard model satisfies Sakharov's conditions for baryogenesis but the CP violation in the KM matrix appears too small to account for the observed asymmetry. In this letter we explore a mechanism through which CP violation can be greatly amplified. First CP is {\it spontaneously} broken through dynamical effects on bubble walls, and the two CP conju

S. Hosono, A. Klemm, S. Theisen, Shing-Tung Yau

We extend the discussion of mirror symmetry, Picard-Fuchs equations, instanton-corrected Yukawa couplings, and the topological one-loop partition function to the case of complete intersections with higher-dimensional moduli spaces. We will develop a new method of obtaining the instanton-corrected Yukawa couplings through a close study of the solutions of the

H. C. Rosu

In the hybrid skyrmion in which an Anti-de Sitter bag is imbedded into the skyrmion configuration a S^{1}\times S^{2} membrane is lying on the compactified spatial infinity of the bag [H. Rosu, Nuovo Cimento B 108, 313 (1993)]. The connection between the quark degrees of freedom and the mesonic ones is made through the membrane, in a way that should still be

Vitaly Tarasov, Alexander Varchenko

Asymptotic solutions to the quantized Knizhnik-Zamolodchikov equation associated with $\frak{gl}_{N+1}$ are constructed. The leading term of an asymptotic solution is the Bethe vector -- an eigenvector of the transfer-matrix of a quantum spin chain model. We show that the norm of the Bethe vector is equal to the product of the Hessian of a suitable function

C. R. Allton, M. Ciuchini, M. Crisafulli, E. Franco

Using the results of several quenched lattice simulations, we predict the value of the strange and charm quark masses in the continuum at the next-to-leading order, $m^{\overline{MS}}_s(μ=2\,\, \rm{GeV})= (127 \pm 18)\,\, \rm{MeV}$ and $m^{\overline{MS}}_{ch}(μ=2 \,\,\rm{GeV})=(1.47 \pm 0.28)\,\, \rm{GeV}$. The errors quoted above have been estimated by taki

S. Adanti, P. Battinelli, R. Capuzzo--Dolcetta, P. W. Hodge

We present a new automatic technique based on Principal Component Analysis and Cluster Analysis, with the aim of its application to the identification of those clumps in unresolved galaxies which likely represent regions of star formation. We test the method by applying it to the galaxy M~31, for which there are already several sets of identifications of OB

Yuliy Baryshnikov

Revised version: some minor errors and typos fixed; exposition watered. Abstract: To a trajectory of a billiard in parallelogram we assign its symbolic trajectory - the sequence of numbers of coordinate plane, to which the faces met by the trajectory are parallel. The complexity of the trajectory is the number of different words of length $n$ occurring in it

Z. Aouissat, R. Rapp, G. Chanfray, P. Schuck

The s-wave correlated $π$-$π$ strength distribution in cold nuclear matter is investigated. The in-medium single pions are renormalized by means of the usual p-wave couplings to nucleons and $Δ$'s. Two groups of models for the $π$-$π$ interaction are studied. The first one uses phenomenological models which reproduce the phase shifts but do not respect t

W. G. Unruh

The effect of the inevitable coupling to external degrees of freedom of a quantum computer are examined. It is found that for quantum calculations (in which the maintenance of coherence over a large number of states is important), not only must the coupling be small but the time taken in the quantum calculation must be less than the thermal time scale, $\hba

M. A. Robson

Consideration of the geometric quantization of the phase space of a particle in an external Yang-Mills field allows the results of the Mackey-Isham quantization procedure for homogeneous configuration spaces to be reinterpreted. In particular, a clear physical interpretation of the `inequivalent' quantizations occurring in that procedure is given.

Yoav Lavi, Yaron Oz, Jacob Sonnenschein

We study the $(1,q=-1)$ model coupled to topological gravity as a candidate to describing $2d$ string theory at the self-dual radius. We define the model by analytical continuation of $q>1$ topological recursion relations to $q=-1$. We show that at genus zero the $q=-1$ recursion relations yield the $W_{1+\infty}$ Ward identities for tachyon correlators on t

Ziemowit Popowicz

We present the new extended supersymmetrization of the Nonlinear Schrodinger Equation by introducing two superbosons fields with the different gradation. Our model is different from this considered by Toppan and in the reduced case (nonextended supersymmetry) is also different from this considered by Kulish and Roelofs and Kersten. We prove that our model is

Mariano Cadoni, Marco Cavaglia

We derive and study a class of cosmological and wormhole solutions of low-energy effective string field theory. We consider a general four-dimensional string effective action where moduli of the compactified manifold and the electromagnetic field are present. The cosmological solutions of the two-dimensional effective theory obtained by dimensional reduction

A. Lesniewski, K. Osterwalder

We apply the concepts of superanalysis to present an intrinsically supersymmetric formulation of the Chern character in entire cyclic cohomology. We show that the cocycle condition is closely related to the invariance under supertranslations. Using the formalism of superfields, we find a path integral representation of the index of the generalized Dirac oper

D. Borthwick, S. Klimek, A. Lesniewski, M. Rinaldi

The purpose of this paper is to apply the framework of non- commutative differential geometry to quantum deformations of a class of Kahler manifolds. For the examples of the Cartan domains of type I and flat space, we construct Fredholm modules over the quantized manifolds using the supercharges which arise in the quantization of supersymmetric generalizatio

D. Borthwick, S. Klimek, A. Lesniewski, M. Rinaldi

We present a general theory of non-perturbative quantization of a class of hermitian symmetric supermanifolds. The quantization scheme is based on the notion of a super Toeplitz operator on a suitable Z_2 -graded Hilbert space of superholomorphic functions. The quantized supermanifold arises as the C^* -algebra generated by all such operators. We prove that

S. P. Brumby, G. C. Joshi, Ronald Anderson

We investigate the outcomes of measurements on correlated, few-body quantum systems described by a quaternionic quantum mechanics that allows for regions of quaternionic curvature. We find that a multi-particle interferometry experiment using a correlated system of four nonrelativistic, spin-half particles has the potential to detect the presence of quaterni

A. Calogeracos, Norman Dombey, Geoffrey B. West

This paper is devoted to a study of possible scaling laws, and their logarithmic corrections, occurring in deep inelastic electropion production. Both the exclusive and semi-exclusive processes are considered. Scaling laws, originally motivated from PCAC and current algebra considerations are examined, first in the framework of the parton model and QCD petur

M. Laine

To study the convergence of the loop expansion at the high-temperature electroweak phase transition, we calculate the 2-loop effective potential of the 3d SU(2)-Higgs model in a general covariant gauge. We find that the loop expansion definitely breaks down for large $ξ$, but converges rather well for smaller values, deep in the broken phase.

Felix Schlumpf

The elastic charge form factors of the pion, kaon, D- and B-mesons are calculated within a relativistic constituent quark model formulated on the light-cone. Our parameter free predictions agree well with the available data. The results are approximately independent of the assumed form of the light-cone wave function, in particular they do not depend on the

M. J. Gibbs, A. Ringwald, B. R. Webber, J. T Zadrozny

We report results obtained with the first complete event generator for electroweak baryon and lepton number violating interactions at supercolliders. We find that baryon number violation would be very difficult to establish, but lepton number violation can be seen provided at least a few hundred L violating events are available with good electron or muon ide

S. M. Troshin, N. E. Tyurin

The appearance of the antishadow scattering mode at Tevatron-Collider energies is considered on the basis of unitarity and geometrical notions on hadron interactions

Chris P. Korthals Altes, Kimyeong Lee, Robert D. Pisarski

We compute the effective potential for the phase of the Wilson line at high temperature in the standard model to one loop order. Besides the trivial vacua, there are metastable states in the direction of $U(1)$ hypercharge. Assuming that the universe starts out in such a metastable state at the Planck scale, it easily persists to the time of the electroweak

Hai-Yang Cheng

Nonfactorizable contributions to exclusive two-body nonleptonic weak decays of heavy mesons arising from color octet currents, characterized by the parameter $r_2$, are extracted from the data. It is found that $r_2$ is equal to $\sim -0.67\,$, $-(0.9\sim 1.1),~-(1.2\sim 1.3)$, $\sim 0.36$ respectively for $D\to \bar{K}π,~\bar{K}^*π,~\bar{K}^*ρ,~\bar{B}\to D

D. Müller

We review both the counting rule and the influence of the evolution in $Q^2$ for the large $x_{Bj}$ behaviour of the valance quark distribution functions. Based on a factorization procedure we present a more general perturbative treatment to compute this behaviour. A complete analysis is performed in the scalar $ϕ^3_{[6]}$-theory for the parton distribution

G. J. Chaitin

Lecture given Wednesday 27 October 1993 at a Physics -- Computer Science Colloquium at the University of New Mexico. The lecture was videotaped; this is an edited transcript. It also incorporates remarks made at the Limits to Scientific Knowledge meeting held at the Santa Fe Institute 24--26 May 1994.

Abraham Loeb, Shude Mao

The central mass distribution of clusters of galaxies can be inferred from gravitationally lensed arcs with known redshifts. For the Abell cluster 2218, this method yields a core mass which is larger by a factor of $2.5 \pm 0.5$ than the value deduced from X-ray observations, under the assumptions that the gas is supported by thermal pressure and that the cl

Pierluigi Monaco

Non-spherical dynamical approximations and models for the gravitational collapse are used to extend the well-known Press \& Schechter (PS) approach, in order to determine analytical expressions for the mass function of cosmic structures. The problem is rigorously set up by considering the intrinsic Lagrangian nature of the mass function. The Lagrangian equat

James E. Lidsey, B. J. Carr, J. H. Gilbert

Blue primordial power spectra with a spectral index $n>1$ can lead to a significant production of primordial black holes in the very early Universe. The evaporation of these objects leads to a number of observational consequences and a model independent upper limit of $n \approx 1.4$. In some cases this limit is strengthened to $n=1.3$. Such limits may be em

C. Kounnas, I. Pavel, F. Zwirner

In the Minimal Supersymmetric Standard Model (MSSM), the scale $M_{SUSY}$ of soft supersymmetry breaking is usually {\em assumed} to be of the order of the electroweak scale. We reconsider here the possibility of treating $M_{SUSY}$ as a dynamical variable. Its expectation value should be determined by minimizing the vacuum energy, after including MSSM quant

Ivan G. Avramidi

It is shown that the heat kernel operator for the Laplace operator on any covariantly constant curved background, i.e. in symmetric spaces, may be presented in form of an averaging over the Lie group of isometries with some nontrivial measure. Using this representation the heat kernel diagonal, i.e. the heat kernel in coinciding points is obtained. Related t

Ard A. Louis, James P. Sethna

We study the effects of phonons on the tunneling of an atom between two surfaces. In contrast to an atom tunneling in the bulk, the phonons couple very strongly, and qualitatively change the tunneling behavior. This is the first example of {\it ohmic} coupling from phonons for a two-state system. We propose an experiment in which an atom tunnels from the tip

John Collins, Joey Huston, Jon Pumplin, Harry Weerts

We present a program to measure the parton densities in the pomeron using diffractive deep inelastic scattering and diffractive photoproduction, and to test the resulting parton densities by applying them to other processes such as the diffractive production of jets in hadron-hadron collisions. Since QCD factorization has been predicted NOT to apply to hard

P. Battinelli, A. Brandimarti, R. Capuzzo--Dolcetta

Galactic open clusters provide an abundant sample of stellar aggregates of various sizes, ages and metal abundances, apt to constitute a template for comparison with star systems in other galaxies. In this paper we present and discuss a standard methodology to synthesize {\sl U,B,V} fluxes and colours, and apply it to a set of 138 open clusters. Results are

Marc Sher

There are two different types of perturbative unification in SUSY GUTs. Perturbative gauge unification is necessary for the extremely successful prediction of $\sin^2θ_w$. ``Perturbative validity'' requires that {\it all} couplings (not just the gauge couplings) remain small; this assumption is essential to the proof that any SUSY GUT must have a lig

Hans-Ulrich Krieger, Ulrich Schäfer

This paper presents \tdl, a typed feature-based representation language and inference system. Type definitions in \tdl\ consist of type and feature constraints over the boolean connectives. \tdl\ supports open- and closed-world reasoning over types and allows for partitions and incompatible types. Working with partially as well as with fully expanded types i

Eli Waxman, Tsvi Piran

Fireballs are an essential part of any cosmological $γ$-ray burst. We drive here a stability criterion for fireballs and show that fireballs are Rayleigh-Taylor unstable in any region in which the entropy decreases outward. The instability begins to operate when the fireball becomes matter dominated. Among the possible implication of the instability are: (i)

J. Riedler

One of several possibilities to construct a quantum theory of gravity is employing the Feynman path integral. This approach is plagued by some problems: the integration measure is not uniquely defined, the Einstein-Hilbert action unbounded, and perturbation theory nonrenormalizable. To make the path integral tractable one can approximate the continuous geome

V. I. Belinicher, A. L. Chernyshev, A. V. Dotsenko, O. P. Sushkov

We study numerically the hole pairing induced by spin-wave exchange. The contact hole-hole interaction is taken into account as well. It is assumed that antiferromagnetic order is preserved at all scales relevant to pairing. The strongest pairing is obtained for the d-wave symmetry of the gap. Dependence of the value of the gap on hole concentration and temp

Yang Sun, Da Hsuan Feng, Hsi-Tseng Chen, Hua Wu

The Projected Shell Model with zero-, two- and four-quasiparticle configurations is used to investigate the level statistics, i.e. chaoticity, of high spin spectroscopy. The model can describe many high spin phenomena and with the present configuration space has sufficient number of levels for statistical analysis. It is found that the degree of chaoticity h

W. Nazarewicz, T. R. Werner, J. Dobaczewski

A shell-correction method is applied to nuclei far from the beta stability line and its suitability to describe effects of the particle continuum is discussed. The sensitivity of predicted locations of one- and two-particle drip lines to details of the macroscopic-microscopic model is analyzed.

Hsien-Chung Kao, Kimyeong Lee

We explore self-dual Chern-Simons Higgs systems with the local $SU(3)$ and global $U(1)$ symmetries where the matter field lies in the adjoint representation. We show that there are three degenerate vacua of different symmetries and study the unbroken symmetry and particle spectrum in each vacuum. We classify the self-dual configurations into three types and

Carl M. Bender, Kimball A. Milton

The Casimir force on a $D$-dimensional sphere due to the confinement of a massless scalar field is computed as a function of $D$, where $D$ is a continuous variable that ranges from $-\infty$ to $\infty$. The dependence of the force on the dimension is obtained using a simple and straightforward Green's function technique. We find that the Casimir force

J. L. F. Barbón, Krešimir Demeterfi

We discuss the general structure of effective hamiltonians for systematic 1/N expansion in QCD using the light-cone quantization. These are second-quantized hamiltonians acting on the Fock space of mesons and glueballs defined by the solution of the $N=\infty$ problem. In the two-dimensional case we find only cubic and quartic interaction terms, and give exp

P. Berglund, M. Henningson

The elliptic genus for arbitrary two dimensional $N=2$ Landau-Ginzburg orbifolds is computed. This is used to search for possible mirror pairs of such models. An important aspect of this work is that there is no restriction to theories for which the conformal anomaly is $\hat c\in\ZZ$, nor are the results only valid at the conformal fixed point.

D. B. Fairlie, J. Nuyts

In this paper all deformations of the general linear group, subject to certain restrictions which in particular ensure a smooth passage to the Lie group limit, are obtained. Representations are given in terms of certains sets of creation and annihilation operators. These creation and annihilation operators may belong to a generalisation of the $q$-quark type

D. B. Fairlie, J. Nuyts

The dual resonance model, which was a precursor of string theory was based upon the idea that two-particle scattering amplitudes should be expressible equivalently as a sum of contributions of an infinite number of $s$ channel poles each corresponding to a finite number of particles with definite spin, or as a similar sum of $t$ channel poles. The famous exa

Mathijs S. Dijkhuizen, Tom H. Koornwinder

The purely algebraic notion of CQG algebra (algebra of functions on a compact quantum group) is defined. In a straightforward algebraic manner, the Peter-Weyl theorem for CQG algebras and the existence of a unique positive definite Haar functional on any CQG algebra are established. It is shown that a CQG algebra can be naturally completed to a $C^\ast$-alge

M. A. Robson

The method of geometric quantization is applied to a particle moving on an arbitrary Riemannian manifold $Q$ in an external gauge field, that is a connection on a principal $H$-bundle $N$ over $Q$. The phase space of the particle is a Marsden-Weinstein reduction of $T^*N$, hence this space can also be considered to be the reduced phase space of a particular

P. Giacconi, S. Ouvry, R. Soldati

We investigate on the plane the axial anomaly for euclidean Dirac fermions in the presence of a background Aharonov--Bohm gauge potential. The non perturbative analysis depends on the self--adjoint extensions of the Dirac operator and the result is shown to be influenced by the actual way of understanding the local axial current. The role of the quantum mech

Wei Chen

We examine the thermal behavior of a theory with charged massive vector matter coupled to Chern-Simons gauge field. We obtain a critical temperature Tc, at which the effective mass of vector field vanishes, and the system transfers from a symmetry broken phase to topological phase. The phase transition is suggested to be of the zeroth order, as the free ener

Noriyuki Fumita

Chiral, conformal and ghost number anomalies are discussed from the viewpoint of the quantum vacuum in Hamiltonian formalism. After introducing the energy cut-off, we derive known anomalies in a new way. We show that the physical origin of the anomalies is the zero point fluctuation of bosonic or fermionic field. We first point out that the chiral U(1) anoma

Carsten Greiner

The production of quarks and antiquarks during a sudden restoration of chiral symmetry, as it might occur in very energetic heavy ion collisions, is considered. If gluons are already present they can assist additively to the overall production: real gluons are partially decaying during such a chiral transition. The total number of produced quarks is calculat

B. Geyer, D. Müller, D. Robaschik

The nonperturbative parton distribution and wave functions are directly related to matrix elements of light-ray (nonlocal) operators. These operators are generalizations of the standard local operators known from the operator product expansion. The renormalization group equation for these operators leads to evolution equations for more general distribution a

Joannis Papavassiliou

In the context of the Standard Model we show how to apply the pinch technique to four-fermion amplitudes with non-conserved external charged currents,in order to construct to one-loop order gauge independent self-energies and vertices. We discuss the technical difficulties arising due to the presence of longitudinal contributions from the W and Goldstone bos

G. Couture, S. Godfrey

We perform a detailed study of the process $e^+e^-\toγν_l\barν_l$ and its sensitivity to anomalous gauge boson couplings of the $γWW$ vertex. We concentrate on LEP II energies, $\sqrt{s}=200$ GeV, and energies appropria- te to the proposed Next Linear Collider (NLC) high energy $e^+e^-$ collider with c.m. energies of 500 GeV and 1 TeV. At 200 GeV, the proces

J. Lopez, D. Nanopoulos, A. Zichichi

An interesting prediction of a string-inspired {\em one-parameter} $SU(5)\times U(1)$ supergravity model, is the fact that the lightest member ($\tilde t_1$) of the top-squark doublet $(\tilde t_1,\tilde t_2)$, may be substantially lighter than the top quark. This sparticle ($\tilde t_1$) may be readily pair-produced at the Tevatron and, if $m_{\tilde t_1}\l

K. Hagiwara, T. Izubuchi, M. Tanaka, I. Watanabe

We study systematically the sensitivity of the photon structure function data on the gluon contents of the photon, by using the leading order Altarelli--Parisi (AP) equations. Charm quark contribution is studied in the quark parton model and by using the massive quark AP equations of Glück, Hoffmann and Reya. The present photon structure function data are fo

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

It is suggested that the measurements of hadronic invariant mass ($m_X$) distributons in the inclusive $B \rightarrow X_{c(u)} l ν$ decays can be useful in extracting the CKM matrix element $|V_{ub}|$. We investigated hadronic invariant mass distributions within the various theoretical models of HQET, FAC and chiral lagrangian as well as ACCMM model. It is a

Rainer Jakob

Independent multiple scattering (`Landshoff') contributions to proton-proton elastic scattering at wide angles are calculated in the quark-diquark model. Results confirm previous observations about the magnitude of these contributions. The use of the quark-diquark model extends the applicability of perturbative QCD calculations down to lower values of mo

J. F. Gunion, Douglas W. McKay, H. Pois

We explore the possibility of a fourth generation in the gauge-coupling-unified, minimal supersymmetric (MSSM) framework. We find that a sequential fourth generation (with a heavy neutrino $ν'$) can still fit, surviving all present experimental constraints, provided $λ_b(M_U)=λ_τ(M_U)$ Yukawa unification is relaxed. For the theory to remain perturbative

Yoshiharu Kawamura, Hitoshi Murayama, Masahiro Yamaguchi

Supersymmetric grand unified theories with non-universal soft supersymmetry breaking terms are studied. By integrating out the superheavy fields at an unification scale, we compute their low-energy effective Lagrangian. We find new contributions to the scalar potential specific to the non-universal supersymmetry breaking. $D$-term contribution to the scalar

P. Menotti, D. Seminara

We prove a positive energy theorem in 2+1 dimensional gravity for open universes and any matter energy-momentum tensor satisfying the dominant energy condition. We consider on the space-like initial value surface a family of widening Wilson loops and show that the energy-momentum of the enclosed subsystem is a future directed time-like vector whose mass is a

Chris Isham, Noah Linden, Stefan Schreckenberg

Gell-Mann and Hartle have proposed a significant generalisation of quantum theory with a scheme whose basic ingredients are `histories' and decoherence functionals. Within this scheme it is natural to identify the space $\UP$ of propositions about histories with an orthoalgebra or lattice. This raises the important problem of classifying the decoherence

Roberto De Pietri, Carlo Rovelli

We consider the eigenvalues of the three-dimensional Weyl operator defined in terms of the (Euclidean) Ashtekar variables, and we study their dependence on the gravitational field. We notice that these eigenvalues can be used as gravitational variables, and derive explicit formulas for their Poisson brackets and their time evolution.

Takashi Torii, Kei-ichi Maeda, Takashi Tachizawa

We re-analyze the globally neutral non-Abelian black holes and present a unified picture, classifying them into two types; Type I (black holes with massless non-Abelian field) and Type II (black holes with ``massive" non-Abelian field). For the Type II, there are two branches: The black hole in the high-entropy branch is ``stable" and almost neutral,

J. H. Han, D. J. Thouless, H. Hiramoto, M. Kohmoto

We have exploited a variety of techniques to study the universality and stability of the scaling properties of Harper's equation, the equation for a particle moving on a tight-binding square lattice in the presence of a gauge field, when coupling to next nearest sites is added. We find, from numerical and analytical studies, that the scaling behavior of

A. H. Castro Neto, H. Q. Lin, H. -Y Chen, J. M. P. Carmelo

We write the Hamiltonian of the Bose gas with two-body repulsive $δ$-function potential in a pseudoparticle operator basis which diagonalizes the problem via the Bethe ansatz. In this operator basis the original bosonic interactions are represented by zero-momentum forward-scattering interactions between Landau-liquid pseudoparticles. We find that this pseud

M. L. Plumer

Magnetic-field -- temperature phase diagrams of the axial next-nearest-neighbor Ising model are calculated within the framework of a Landau-type expansion of the free energy derived from molecular-field theory. Good qualitative agreement is found with recently reported results on body-centered-tetragonal $UPd_2Si_2$. This work is expected to also be relevant

P. Di Francesco, E. Guitter

We study the problem of folding of the regular triangular lattice in the presence of bending rigidity K and magnetic field h (conjugate to the local normal vectors to the triangles). A numerical study of the transfer matrix of the problem shows the existence of three first order transition lines in the (K,h) plane separating three phases: a folded phase, a p

D. López, G. Nieva, F. de la Cruz, H. J. Jensen

We measured the current induced loss of vortex correlation in YBCO crystals using the pseudo DC flux transformer geometry. We find that the current $I_{cut}$ at which the top and bottom voltage differ is a linear function of temperature independent of pinning. Although the vortex correlation length at $I_{cut}$ coincides with the sample thickness, the experi

Naoshi Sugiyama, Joseph Silk

We investigate the dependence of large angular scale cosmic microwave background anisotropies on various initial conditions, including both adiabatic and isocurvature perturbations and the initial power law index $n$, in a variety of low-$Ω$ cosmological models. Cosmological constant- dominated flat models and inflationary open adiabatic models, with $n_{\rm

Pierluigi Monaco, Giuliano Giuricin, Fabio Mardirossian, Marino Mezzetti

Using an extensive sample of nearby galaxies (the Nearby Galaxies Catalog, by Tully), we investigate the environment of the galaxies hosting low-luminosity AGNs (Seyferts and LINERs). We define the local galaxy density, adopting a new correction for the incompleteness of the galaxy sample at large distances. We consider both a complete sample of bright and n

F. A. Rasio

A simple analytic calculation is presented for the secular evolution of the eccentricities in a hierarchical triple system such as the one containing the millisecond pulsar PSR 1620-26 in M4. If the second companion of PSR 1620-26 is of stellar mass ($m_2\ga0.1\,M_\odot$), an eccentricity as large as that observed today for the inner binary ($e_1\simeq0.03$)

I. -A. Yadigaroglu, Roger W. Romani

The computer animation illustrates the geometries described in a paper by the same authors. The preprint is available as number 9401045. The opening scene shows dipole field lines emanating from the polar caps of a rotating neutron star. The dipole axis is inclined along the green rods. The field lines shown are defined from the condition that they be tangen

Stephen J. Montgomery-Smith

A new proof of a result of Lutz Weis is given, that states that the stability of a positive strongly continuous semigroup $(e^{tA})_{t \ge 0}$ on $L_p$ may be determined by the quantity $s(A)$. We also give an example to show that the dichotomy of the semigroup may not always be determined by the spectrum $σ(A)$.

V. de la Pena, Stephen J. Montgomery-Smith, Jerzy Szulga

We prove decoupling inequalities for random polynomials in independent random variables with coefficients in vector space. We use various means of comparison, including rearrangement invariant norms (e.g., Orlicz and Lorentz norms), tail distributions, tightness, hypercontractivity, etc.

Pawel Hitczenko, Stephen J. Montgomery-Smith

Let (f_n) and (g_n) be two sequences of random variables adapted to an increasing sequence of $σ$-algebras $({\cal F}_n)$ such that the conditional distributions of f_n and g_n given ${\cal F}_{n-1}$ coincide, and such that the sequence (g_n) is conditionally independent. Then it is known that $\normo{\sum f_k}_p \le C \normo{\sum g_k}_p$, $1 \le p \le \inft

F. Igloi, L. Turban

We consider the surface critical behaviour of a semi-infinite two-dimensional layered Ising model, where the couplings perpendicular to the surface follow the aperiodic Rudin-Shapiro sequence. The model has unusual critical properties: depending on the strength of the modulation, at the bulk critical point the surface magnetization is either discontinuous or

M. Ciuchini, E. Franco, G. Martinelli, L. Reina

We present upgraded theoretical predictions for inclusive and exclusive radiative decays of {\it B} mesons. Our results include those next-to-leading order corrections that have already been computed. Our best estimates in the Standard Model are $BR(B \rightarrow K^* γ)=(4.3 \pm 0.9^{ +1.4}_{-1.0}) \times 10^{-5}$, $BR(B \rightarrow X_s γ) =(1.9 \pm 0.2\pm 0

Paolo Catelan

We present a new formalism which allows to derive the general Lagrangian dynamical equations for the motion of gravitating particles in a non--flat Friedmann universe with arbitrary density parameter $Ω$ and no cosmological constant. We treat the set of particles as a Newtonian collisionless fluid. The non--linear dynamical evolution of the fluid element tra

Jewan Kim, C. J. Park, Yongsung Yoon

It is found that the deviation of an effective potential from the quartic form is related to the metric and vector torsion dependencies of the effective potential in the vector torsion coupled conformally induced gravity.

Steven H. Simon, Bertrand I. Halperin

We consider a 2D electron system in a strong magnetic field, where the local Hall resistivity $ρ_{xy}(\vec r)$ is a function of position and $ρ_{xx}(\vec r)$ is small compared to $ρ_{xy}$. Particularly if the correlations fall off slowly with distance, or if fluctuations exist on several length scales, one finds that the macroscopic longitudinal resistivity

Cheng-Li Wu, Da Hsuan Feng, Mike W. Guidry, Hsi-Tseng Chen

It is shown that the SU(3) symmetry of the fermion dynamical symmetry model is essentially preserved even for highly nondegenerate spherical single-particle energies. The breaking of SU(3) symmetry by single-particle energy terms for either normal deformation or superdeformation occurs only through an indirect Pauli effect and is significant only when the sp

M. S. Fayache, L. Zamick

The magnetic dipole strength and energy-weighted strength distribution is calculated in $^8\mbox{Be}$, as well as the separate orbit and spin parts. All $ΔN$=$2$ excitations over and above (and including) the configuration $0s^4$$0p^4$ are included. The interaction has a central, two-body spin-orbit and a tensor part. The energy- independent and energy-weigh

Holger Dette, William J. Studden

For the generalized Jacobi, Laguerre and Hermite polynomials $P_n^{(α_n, β_n)} (x), L_n^{(α_n)} (x),$\break $H_n^{(γ_n)} (x)$ the limit distributions of the zeros are found, when the sequences $α_n$ or $β_n$ tend to infinity with a larger order than $n$. The derivation uses special properties of the sequences in the corresponding recurrence formulae. The res

Holger Dette

For the Hahn and Krawtchouk polynomials orthogonal on the set $\{0, \ldots,N\}$ new identities for the sum of squares are derived which generalize the trigonometric identity for the Chebyshev polynomials of the first and second kind. These results are applied in order to obtain conditions (on the degree of the polynomials) such that the polynomials are bound

Holger Dette

We consider the problem of maximizing the sum of squares of the leading coefficients of polynomials $P_{i_1}(x),\ldots ,P_{i_m}(x)$ (where $P_j(x)$ is a polynomial of degree $j$) under the restriction that the sup-norm of $\sum_{j=1}^m P_{i_j}^2(x)$ is bounded on the interval $[-b,b]$ ($b>0$). A complete solution of the problem is presented using duality the

Michel Talagrand

We present three methods to construct majorizing measures in various settings. These methods are based on direct constructions of increasing sequences of partitions through a simple exhaustion procedure rather than on the construction of well separated ultrametric subspaces. The first scheme of construction provides a simple unified proof of the Majorizing M

Yoav Benyamini

This is a survey of results on the classification of Banach spaces as metric spaces. It is based on a series of lectures I gave at the Functional Analysis Seminar in 1984-1985, and it appeared in the 1984-1985 issue of the Longhorn Notes. I keep receiving requests for copies, because some of the material here does not appear elsewhere and because the Longhor

Michel Talagrand

The concentration of measure prenomenon roughly states that, if a set $A$ in a product $Ω^N$ of probability spaces has measure at least one half, ``most'' of the points of $Ω^N$ are ``close'' to $A$. We proceed to a systematic exploration of this phenomenon. The meaning of the word ``most'' is made rigorous by isoperimetric-type inequ

D. Borthwick, T. Paul, A. Uribe

Let $X$ be a compact Kahler manifold and $L\to X$ a quantizing holomorphic Hermitian line bundle. To immersed Lagrangian submanifolds $Λ$ of $X$ satisfying a Bohr-Sommerfeld condition we associate sequences $\{ |Λ, k\rangle \}_{k=1}^\infty$, where $\forall k$ $|Λ, k\rangle$ is a holomorphic section of $L^{\otimes k}$. The terms in each sequence concentrate o

Hidenori Sonoda

We consider the linear space of composite fields as an infinite dimensional vector bundle over the theory space whose coordinates are simply the parameters of a renormalized field theory. We discuss a geometrical expression for the short distance singularities of the composite fields in terms of beta functions, anomalous dimensions, and a connection. (Based