February 1994 arXiv papers — page 5

Eduardo Cattani, Pierre Deligne, Aroldo Kaplan

Let $f: X \rightarrow S$ be a family of non singular projective varieties parametrized by a complex algebraic variety $S$. Fix $s \in S$, an integer $p$, and a class $h \in {\rm H}^{2p}(X_s,\Z)$ of Hodge type $(p,p)$. We show that the locus, on $S$, where $h$ remains of type $(p,p)$ is algebraic. This result, which in the geometric case would follow from the

L. Reina

We present the results for the Next-to-Leading Order effective hamiltonian for $ΔS\!=\! 1$ decays, in presence of both QCD and QED corrections, and update the existing theoretical predictions for $ε^\prime/ε$. To appear on the Proceedings of the Third KEK Topical Conference on CP Violation, its Implications to Particle Physics and Cosmology, Tsukuba, 16-18 N

Igor V. Dolgachev, Yi Hu

Geometric Invariant Theory gives a method for constructing quotients for group actions on algebraic varieties which in many cases appear as moduli spaces parametrizing isomorphism classes of geometric objects (vector bundles, polarized varieties, etc.). The quotient depends on a choice of an ample linearized line bundle. Two choices are equivalent if they gi

T. Kinoshita, M. Nio

Terms contributing to the hyperfine structure of the muonium ground state at the level of few tenths of kHz have been evaluated. The $α^2 (Zα)$ radiative correction has been calculated numerically to the precision of 0.02 kHz. Leading $\ln (Zα)$ terms of order $α^{4-n} (Zα)^n , n=1,2,3,$ and some relativistic corrections have been evaluated analytically. The

Jun Nishimura, Shinya Tamura, Asato Tsuchiya

Using (2+$ε$)-dimensional quantum gravity recently formulated by Kawai, Kitazawa and Ninomiya, we calculate the scaling dimensions of manifestly generally covariant operators in two-dimensional quantum gravity coupled to $(p,q)$ minimal conformal matter. Although the spectrum includes all the scaling dimensions of the scaling operators in the matrix model ex

Valery Alexeev

Let $ε, C$ be two positive real numbers, and $\mathcal C \subset \mathbb R$ be a DCC (descending chain condition) set. Let $(X, B = \sum b_j B_j)$ denote a projective surface with an $\mathbb R$-divisor. Then (1) The class $\{X\}$ of surfaces for which there exists a divisor $B$ such that $(X,B)$ is $ε$-log terminal and $-(K_X + B)$ is nef (excluding only th

N. N. Nikolaev, A. Szczurek, J. Speth, J. Wambach

The spectral function, measured in $A(e,e'p)$ reactions, is distorted by the final-state interaction of the struck proton with the residual nucleus. This causes a broadening of the observed transverse-momentum distribution which is large even in the $d(e,e'p)$ reaction. We discuss the effects of this $p_{\perp}$-broadening on the nuclear transparency

S. A. Kulagin, G. Piller, W. Weise

We present a unified description of nuclear deep inelastic scattering (DIS) over the whole region $0<x<1$ of the Bjorken variable. Our approach is based on a relativistically covariant formalism which uses analytical properties of quark correlators. In the laboratory frame it naturally incorporates two mechanisms of DIS: (I) scattering from quarks and antiqu

D. Dalmazi, A. de Souza Dutra

We comment on a recent paper by Chaichian et al. (Phys.Rev.Lett. 71(1993)3405).

Dongsu Bak, R. Jackiw, So-Young Pi

A many--body Schrödinger equation for non--Abelian Chern--Simons particles is obtained from both point--particle and field--theoretic pictures. We present a particle Lagrangian and a field theoretic Lagrange density, and discuss their properties. Both are quantized by the symplectic method of Hamiltonian reduction. An $N$--body Schrödinger equation for the p

Gil Gat, O. W. Greenberg

We give the first operator solution of the Schwinger model that obeys the canonical commutation relations in a covariant guage.

M. A. Semenov-Tian-Shansky

We compute the Poisson bracket relations for the monodromy matrix of the auxiliary linear problem. If the basic Poisson bracket relations of the model contain derivatives, this computation leads to a peculiar type of symmetry breaking which accounts for a &#39;spontaneous quantization of the underlying global gauge group. A classification of possible pattern

H. J. de Vega, Luca Mezincescu, Rafael I. Nepomechie

We determine the excitations and $S$ matrix of an integrable isotropic antiferromagnetic quantum spin chain of alternating spin 1/2 and spin 1. There are two types of gapless one-particle excitations: the usual spin 1/2 (``spinor&#39;&#39;) kink, and a new spin 0 (``scalar&#39;&#39;) kink. Remarkably, the scalar-spinor scattering is nontrivial, yet the spino

B. Durhuus

We consider a class of spin systems on randomly triangulated surfaces as discrete approximations to conformal matter fields coupled to 2d gravity. On the basis of certain universality assumptions we argue that at critical points with diverging string susceptibility the model either exhibits mean field behaviour or it can effectively be described by a conform

C. Schwiebert

The correspondence of the braid group on a handlebody of arbitrary genus to the algebra of Yang-Baxter and extended reflection equation operators is shown. Representations of the infinite dimensional extended reflection equation algebra in terms of direct products of quantum algebra generators are derived, they lead to a representation of this braid group in

Dongsu Bak, Choonkyu Lee

Dynamics of a BPS dyon in a weak, constant, electromagnetic field is studied through a perturbative analysis of appropriate non-linear field equations. The full Lorentz force law for a BPS dyon is established. Also derived are the radiation fields accompanying the motion.

Yoshitaka Okumura

Standard model is reconstructed using the generalized differential calculus extended on the discrete space $M_4\times Z_3$. $Z_3$ is necessary for the inclusion of strong interaction. Our starting point is the generalized gauge field expressed as $A(x,y)=\!\sum_{i}a^\dagger_{i}(x,y){\bf d}a_i(x,y), (y=0,\pm)$, where $a_i(x,y)$ is the square matrix valued fun

Yoshitaka Okumura

Weinberg-Salam theory and $SU(5)$ grand unified theory are reconstructed using the generalized differential calculus extended on the discrete space $M_4\times Z_{\mathop{}_{N}}$. Our starting point is the generalized gauge field expressed by $A(x,n)=\!\sum_{i}a^\dagger_{i}(x,n){\bf d}a_i(x,n), (n=1,2,\cdots N)$, where $a_i(x,n)$ is the square matrix valued f

P. Fendley, H. Saleur

We show how to derive exact boundary $S$ matrices for integrable quantum field theories in 1+1 dimensions using lattice regularization. We do this calculation explicitly for the sine-Gordon model with fixed boundary conditions using the Bethe ansatz for an XXZ-type spin chain in a boundary magnetic field. Our results agree with recent conjectures of Ghoshal

K. S. Gupta, C. Rosenzweig

We study the decay of hadrons based on a semiclassical string model. By including quark mass effects we find that the width to mass ratio $\G/m$ is an increasing function of $m$, which increases most rapidly for massive quarks. This is consistent with the available data. The decay probability of hadrons on the leading Regge trajectories is computed taking th

Duane A. Dicus, Roberto Vega

Analytic expressions are given for the $τ$ decays into three charged leptons, $τ\rta \ell\ell\overline \ellν_τ\overline ν_\ell$, where the $\ell$ are combinations of electrons and muons, and for the radiative decays $τ\rta γ\ellν_τ\overline ν_\ell$. The branching ratios are sensitive functions of whether the final state $\ell$ are muons or electrons.

Lay Nam Chang, Daniel Ng, John N. Ng

In this paper, we study the phenomenology of right-handed neutrino isosinglets. We consider the general situation where the neutrino masses are not necessarily given by $m_D^2/M$, where $m_D$ and $M$ are the Dirac and Majorana mass terms respectively. The consequent mixing between the light and heavy neutrinos is then not suppressed, and we treat it as an in

Ingolf Kuss

The high-energy behavior of vector-boson scattering amplitudes is examined within an effective theory for non-standard self-interactions of electroweak vector-bosons. Irrespectively of whether this theory is brought into a gauge invariant form by including non-standard interactions of a Higgs particle I find that terms that grow particularly strongly with in

Jorge Ananias Neto

Another stabilizer term is used in the classical Hamiltonian of the Skyrme Model that permits in a much simple way the generalization of the higher-order terms in the pion derivative field. Improved numerical results are obtained.

Jochen Rau

A source term in the quantum Boltzmann equation, which accounts for the spontaneous creation of $e^+e^-$-pairs in external electric fields, is derived from first principles and evaluated numerically. Careful analysis of time scales reveals that this source term is generally non-Markovian. This implies in particular that there may be temporary violations of t

Hitoshi Murayama

The importance of the mass spectroscopy of the superparticles is emphasized. It will be shown that the gauge coupling constants give us information on the GUT-scale mass spectrum once the superparticle masses are known. The gaugino masses will provide us a model-independent test of the grand unification irrespective of the symmetry breaking pattern. The sfer

Yoshiharu Kawamura, Hitoshi Murayama, Masahiro Yamaguchi

We study the mass spectrum of superparticles within supersymmetric grand unified models. For gaugino masses, it is pointed out that the GUT-relation in the $SU(5)$ model is applicable to a more general case where a grand-unified gauge group breaks down to the standard model gauge group by several steps. We also show that the mass spectrum of squarks and slep

M. Carena, S. Pokorski, M. Olechowski, C. E. M. Wagner

The condition of unification of gauge couplings in the minimal supersymmetric standard model provides successful predictions for the weak mixing angle as a function of the strong gauge coupling and the supersymmetric threshold scale. In addition, in some scenarios, e.g.\ in the minimal SO(10) model, the tau lepton and the bottom and top quark Yukawa coupling

M. Martellini, M. Spreafico, K. Yoshida

The possible interpretations of a new continuum model for the two-dimensional quantum gravity for $d>1$ ($d$=matter central charge), obtained by carefully treating both diffeomorphism and Weyl symmetries, are discussed. In particular we note that an effective field theory is achieved in low energy (large area) expansion, that may represent smooth self-avoidi

Viqar Husain, Erik A. Martinez, Dario Nunez

We give an exact spherically symmetric solution for the Einstein-scalar field system. The solution may be interpreted as an inhomogeneous dynamical scalar field cosmology. The spacetime has a timelike conformal Killing vector field and is asymptotically conformally flat. It also has black or white hole-like regions containing trapped surfaces. We describe th

Viqar Husain

The self-dual Einstein equation (SDE) is shown to be equivalent to the two dimensional chiral model, with gauge group chosen as the group of area preserving diffeomorphisms of a two dimensional surface. The approach given here leads to an analog of the Plebanski equations for general self-dual metrics, and to a natural Hamiltonian formulation of the SDE, nam

Viqar Husain

The Einstein equations for spacetimes with two commuting spacelike Killing field symmetries are studied from a Hamiltonian point of view. The complexified Ashtekar canonical variables are used, and the symmetry reduction is performed directly in the Hamiltonian theory. The reduced system corresponds to the field equations of the SL(2,R) chiral model with add

R. Cote, A. -M. S. Tremblay

In the large $U$ limit, the ground state of the half-filled, nearest-neighbor Hubbard model on the triangular lattice is the three-sublattice antiferromagnet. In sharp contrast with the square-lattice case, where transverse spin-waves and charge excitations remain decoupled to all orders in $t/U$, it is shown that beyond leading order in $t/U$ the three Gold

O. Golinelli, Th. Jolicoeur, R. Lacaze

We present results of exact diagonalizations of the isotropic antiferromagnetic S=1 Heisenberg chain by the Lanczos method, for finite rings of up to N=22 sites. The Haldane gap G(N) and the ground state energy per site e(N) converge, with increasing N, faster than a power law. By VBS and Shanks transformations, the extrapolated values are G=0.41049(2) and e

Hans C. Fogedby

We consider the combined effects of a power law Lévy step distribution characterized by the step index $f$ and a power law waiting time distribution characterized by the time index $g$ on the long time behavior of a random walker. The main point of our analysis is a formulation in terms of coupled Langevin equations which allows in a natural way for the incl

H. T. C. Stoof

We derive the equation of state of a dilute atomic Bose gas with an interatomic interaction that has a negative scattering length and argue that two continuous phase transitions, occuring in the gas due to quantum degeneracy effects, are preempted by a first-order gas-liquid or gas-solid transition depending on the details of the interaction potential. We al

Siegfried Grossmann, Detlef Lohse, Victor L&#39;vov, Itamar Procaccia

We study analytically and numerically the corrections to scaling in turbulence which arise due to the finite ratio of the outer scale $L$ of turbulence to the viscous scale $η$, i.e., they are due to finite size effects as anisotropic forcing or boundary conditions at large scales. We find that the deviations $\dzm$ from the classical Kolmogorov scaling $ζ_m

Eyal Maoz

The dark matter in Galactic halos, or some fraction of it, may be in the form of dark clusters which consist of small mass objects. Carr & Lacey (1987) have derived the permissible properties of such systems, and proposed the existence of dark clusters with mass of order $10^6\solarmass$ to explain some of the observed dynamical properties of the stellar dis

D. S. L. Soares

The rotation curves of 20 spiral galaxies are examined in the light of a toy model (Soares 1992) which has as the main feature the assignment of a high M/L ratio (=30; Ho=50 km/s/Mpc) to the visible matter. The observed rotation of all galaxies can be accommodated without the assumption of a dark halo. Moreover, the suggestion is made that the fact that almo

B. Paczynski, K. Z. Stanek, A. Udalski, M. Szymanski

The color-magnitude diagram of $ \sim 3 \times 10^5 $ stars obtained for Baade&#39;s Window towards the Galactic bulge with the OGLE project reveals a surprisingly narrow main sequence due to galactic disk stars at a distance of $d \sim 2 $ kpc, i.e. at the location of the Sagittarius spiral arm. A more careful analysis indicates there is an excess in the nu

Leandros Perivolaropoulos

Using a simple analytic model based on seed superposition we obtain the spectrum of microwave background perturbations induced by cosmic strings on all angular scales larger than about 2 armin. We assume standard recombination in an Einstein de Sitter universe with $h=1/2$ and study the fluctuation spectrum along a great circle in the sky. Doppler and potent

Leandros Perivolaropoulos, Richhild Moessner, Robert Brandenberger

ABSRACT: We review recent progress on testing the hypothesis of the existence of cosmic string perturbations in microwave background maps. Using an analytical model for the string network we show that the predicted amplitude and spectrum of MBR fluctuations are consistent with the COBE data for a reasonable value of the single free parameter of the string mo

Michael Dine

There are many reasons to believe that there might be new sources of CP-violation beyond the phases of the KM matrix. One of these is the possibility of electroweak baryogenesis. We describe some recent developments in this subject and make some comments on the possibility that the minimal standard model might itself be the origin of the baryon asymmetry. To

Seth Major, Lee Smolin

Histories and measures for quantum cosmology are investigated through a quantization of the Bianchi IX cosmology using path integral techniques. The result, derived in the context of Ashtekar variables, is compared with earlier work. A non-trivial correction to the measure is found, which may dominate the classical potential for universes on the Planck scale

Hiroyuki Yabu, F. Myhrer, K. Kubodera

The results for meson condensation in the literature vary markedly depending on whether one uses chiral perturbation theory or the current-algebra-plus-PCAC approach. To elucidate the origin of this discrepancy, we re-examine the role of the sigma-term in meson condensation. We find that the resolution of the existing discrepancy requires a knowledge of term

Giovanni Landi, Nguyen Ai Viet, Kameshwar C. Wali

We present a unified description of gravity and electromagnetism in the framework of a $Z_2$ noncommutative differential calculus. It can be considered as a ``discrete version&#34; of Kaluza-Klein theory, where the fifth continuous dimension is replaced by two discrete points. We derive an action which coincides with the dimensionally reduced one of the ordi

K. Steininger, W. Weise

Scalar matrix elements involving strange quarks are studied in several models. Apart from a critical reexamination of results obtained in the Nambu and Jona-Lasinio model we study a scenario, motivated by instanton physics, where spontaneous chiral symmetry breaking is induced by the flavor-mixing &#39;t Hooft interaction only. We also investigate possible c

Kikuo Harigaya, Shuji Abe

A theory of optical excitations by using a tight binding model with long-range Coulomb interactions is developed. The model is applied to a C60 molecule and a cluster, and is treated by the Hartree-Fock approximation followed by a configuration interaction method. Lattice fluctuations are taken into account by a bond disorder model. We first examine what str

T. D. Cohen, J. Milana

A new method to extract $|V_{\rm bc}|$ is proposed based on a sum--rule for semileptonic decays of the $B$ meson. The method relies on much weaker assumptions than previous approaches which are based on heavy--quark symmetry. This sum--rule only relies on the assumption that the virtual $c \overline{c}$ pair content of the $B$ meson can be neglected. The ext

Fiorenzo Bastianelli, Nobuyoshi Ohta, Jens Lyng Petersen

We show that the $N=2$ superstrings may be viewed as a special class of the $N=4$ superstrings and demonstrate their equivalence. This allows us to realize all known string theories based on linear algebras and with $N<4$ supersymmetries as special choices of the vacua in the $N=4$ superstring.

Andrew R Liddle, Michael S Turner

To first order in the deviation from scale invariance the inflationary potential and its first two derivatives can be expressed in terms of the spectral indices of the scalar and tensor perturbations, $n$ and $n_T$, and their contributions to the variance of the quadrupole CBR temperature anisotropy, $S$ and $T$. In addition, there is a ``consistency relatio

Y. Oshiro, K. Nakamura, A. Tomimatsu

We present a self-similar model of spherically symmetric collapse of a massless scalar field with a parameter $p$. The black hole formation is explicitly shown to occur only in the strong-field implosion of $p >1$. The field evolution in the critical limit $ p \rightarrow 1 $ is compared with numerical results found by Choptuik.

Pierre Minnaert, Stoyan Toshev

It is shown that the well known Racah sum rule and Biedenharn-Elliott identity satisfied by the recoupling coefficients or by the $6-j$ symbols of the usual rotation $SO(3)$ algebra can be extended to the corresponding features of the super-rotation $osp(1|2)$ superalgebra. The structure of the sum rules is completely similar in both cases, the only differen

Q-Han Park

A general Lagrangian formulation of integrably deformed G/H-coset models is given. We consider the G/H-coset model in terms of the gauged Wess-Zumino-Witten action and obtain an integrable deformation by adding a potential energy term $Tr(gTg^{-1}\Tb )$, where algebra elements $T, \Tb $ belong to the center of the algebra {\bf h} associated with the subgroup

Misao Sasaki, Ewan D. Stewart, Takahiro Tanaka

The tunneling rates for scalar fields with quartic potentials in de Sitter space in the limit of no gravitational back reaction are calculated numerically and the results are fitted by analytic formulae.

Alvaro Arias, Jeff Farmer

We examine some structural properties of (injective and projective) tensor products of $\ell_p$-spaces (projections, complemented subspaces, reflexivity, isomorphisms, etc.). We combine these results with combinatorial arguments to address the question of primarity for these spaces and their duals. Our main results are: \medbreak \item{(1)} If $1<p<\infty$,

Nathan Seiberg

We consider four dimensional quantum field theories which have a continuous manifold of inequivalent exact ground states -- a moduli space of vacua. Classically, the singular points on the moduli space are associated with extra massless particles. Quantum mechanically these singularities can be smoothed out. Alternatively, new massless states appear there. T

I. G. Korepanov

A completely integrable dynamical system in discrete time is studied by means of algebraic geometry. The system is associated with factorization of a linear operator acting in a direct sum of three linear spaces into a product of three operators, each acting nontrivially only in a direct sum of two spaces, and the following reversing of the order of factors.

T. Karki, A. J. Niemi

In this article we review the Duistermaat-Heckman integration formula and the ensuing equivariant cohomology structure, in the finite dimensional case. In particular, we discuss the connection between equivariant cohomology and classical integrability. We also explain how the integration formula is derived, and explore some possible new directions that could

Werner Nahm

Fusion is defined for arbitrary lowest weight representations of $W$-algebras, without assuming rationality. Explicit algorithms are given. A category of quasirational representations is defined and shown to be stable under fusion. Conjecturally, it may coincide with the category of representations of finite quantum dimensions.

A. W. Ackley, P. H. Frampton, B. Kayser, C. N. Leung

In the aspon model solution of the strong $CP$ problem, there is a gauged $U(1)$ symmetry, spontaneously broken by the same vacuum expectation value which breaks $CP$, whose massive gauge boson provides an additional mechanism of weak $CP$ violation. We calculate the $CP$ asymmetries in $B$ decays for the aspon model and show that they are typically smaller

Barry R. Holstein, A. M. Nathan

Recent experimental results on the proton and neutron polarizabilities are examined from the point of view of backward dispersion relations. Results are found to be in reasonable agreement with the measured values. A rigorous relationship between the nucleon and pion polarizabilities is derived and shown to be in excellent agreement with several models.

A. V. Kotikov, G. Parente, O. A. Sampayo

The leading effect of light gluinos on the deep inelastic longitudinal structure function is calculated. We present the explicit analitic expression for the Wilson coefficient. After convolution with quark, gluon and gluino distributions we found that the size of the contribution is of order a few percent of the total $F_L$. Some phenomenological implication

A. Patrascioiou, E. Seiler

In gauge theories with continuous groups there exist classical solutions whose energy vanishes in the thermodynamic limit (in any dimension). The existence of these super-instantons is intimately related to the fact that even at short distances perturbation theory can fail to produce unique results. This problem arises only in non-Abelian models and only sta

Piotr Bizoń

A brief review of recent research on soliton and black hole solutions of Einstein&#39;s equations with nonlinear field sources is presented and some open questions are pointed out.

M. Stone, M. P. A. Fisher

An effective wavefunction for the edge excitations in the Fractional quantum Hall effect can be found by dimensionally reducing the bulk wavefunction. Treated this way the Laughlin $ν=1/(2n+1)$ wavefunction yields a Luttinger model ground state. We identify the edge-electron field with a Luttinger hyper-fermion operator, and the edge electron itself with a n

Giuseppe Santoro, Michele Fabrizio

We present a restricted solid on solid hamiltonian for fcc (110) surfaces. It is the simplest generalization of the exactly solvable BCSOS model which is able to describe a $(2\times 1)$ missing-row reconstructed surface. We study this model by mapping it onto a quantum spin-1/2 chain of the Heisenberg type, with second and third neighbor $S^z_iS^z_j$ coupli

E. V. Podivilov

Self - consistent temperature dependence of the average magnetization in quantum Heisenberg ferromagnet is obtained as a first approximation of perturbation theory on an inverse radius by application of the functional method for quantum ferromagnet. The experimental data are compared with the theoretical results for {\bf EuO} ferromagnet. A quantitative agre

Michael Chertkov, Igor Kolokolov

Infinite-temperature long-time dynamics of Heisenberg model ${\bf\hat{H}}=-\frac{1}{2}\sum_{i,j}J_{ij} \hat{\vec{S}}_{i}\hat{\vec{S}}_{j}$ is investigated. It is shown that the quantum spin pair-correlator is equal to the correlator of classically evaluated vector field averaged over the initial conditions with respect to the gaussian measure. In the contini

E. Sorensen, I Affleck

The $S=1$ antiferromagnetic Heisenberg chain both with and without single ion anisotropy is studied. Using the recently proposed density matrix renormalization group technique we calculate the energy gaps as well as several different correlation functions. The two gaps, $Δ_{||}, Δ_\perp$, along with associated correlation lengths and velocities are determine

V. A. Hughes, R. J. Cohen, S. Garrington

New high resolution 6 cm observations have been made on Cepheus A using MERLIN, and combined with new VLA observations at 3.7 cm. Angular resolution with the latter was 200 mas, and with MERLIN was 60 mas, except for isolated unresolved sources where 33 mas was achieved. Unresolved objects at 60 mas were observed in Sources 2, 3, and in particular 9 which al

W. J. Anderson, H. J. Haubold, A. M. Mathai

As theoretical knowledge and experimental verification of nuclear cross sections increases it becomes possible to refine analytic representations for nuclear reaction rates. In this paper mathematical/statistical techniques for deriving closed-form representations of thermonuclear functions are summarized and numerical results for them are given.The purpose

H. J. Haubold, A. M. Mathai

The paper presents results for deriving closed-form analytic solutions of the non-relativistic linear perturbation equations, which govern the evolution of inhomogeneities in a homogeneous spatially flat multicomponent cosmological model. Mathematical methods to derive computable forms of the perturbations are outlined.

D. A. Frail, P. J. Diamond, J. M. Cordes, H. J. Van Langevelde

We have made angular broadening measurements in the satellite line of the OH molecule at 1612 MHz of 8 OH/IR stars located near the Galactic Center with the Very Large Array. Early observations with the Very Long Baseline Array had revealed a region of pronounced scattering approximately centered on SgrA*. These new observations show that the compact line em

G. G. Fahlman, Nick Kaiser, Gordon Squires, David Woods

We explore the dark matter distribution in ms1224.7+2007 using the gravitational distortion of the images of faint background galaxies. Projected mass image reconstruction reveals a highly significant concentration coincident with the X-ray and optical location. The concentration is seen repeatably in reconstructions from independent subsamples and the azimu

Wolfram Decker, Sorin Popescu

This is a survey on the classification of smooth surfaces in P^4 and smooth 3-folds in P^5. We recall the corresponding results arising from adjunction theory and explain how to construct examples via syzygies. We discuss some examples in detail and list all families of smooth non-general type surfaces in P^4 and 3-folds in P^5 known to us.

Natalie S. Glance, Tad Hogg, Bernardo A. Huberman

We present a two-level model of organizational training and agent production. Managers decide whether or not to train based on both the costs of training compared to the benefits and on their expectations and observations of the number of other firms that also train. Managers also take into account the sum of their employees&#39; contributions and the averag

A. Kempf, Shahn Majid

We introduce an algebraic theory of integration on quantum planes and other braided spaces. In the one dimensional case we obtain a novel picture of the Jackson $q$-integral as indefinite integration on the braided group of functions in one variable $x$. Here $x$ is treated with braid statistics $q$ rather than the usual bosonic or Grassmann ones. We show th

D. V. Khveshchenko, P. B. Wiegmann

Recent experiments on inelastic light scattering in a number of insulating cuprates [1] revealed a new excitation appearing in the case of crossed polarizations just below the optical absorption threshold. This observation suggests that there exists a local exciton-like state with an odd parity with respect to a spatial reflection. We present the theory of h

T. E. Clark, B. Haeri, S. T. Love, M. A. Walker

Nonperturbative triviality and vacuum stability mass bounds are obtained for the Higgs scalar and top quark degrees of freedom in the standard electroweak model using Wilson renormalization group techniques. Particular attention is given to the effect of the generalized top Yukawa coupling on the scalar mass upper bound.

Giorgio Ottaviani, Günther Trautmann

Mathematical instanton bundles on $ P_3$ have their analogues in rank--$2n$ instanton bundles on odd dimensional projective spaces $ P_{2n+1}$. The families of special instanton bundles on these spaces generalize the special &#39;tHooft bundles on $ P_3$. We prove that for a special symplectic instanton bundle $ E$ on $ P_{2n+1}$ with $c_2=k$ $h^1End( E) = 4

Ngee Pong Chang

The BP-FTW effective action is a good laboratory to study the nature of chiral symmetry at high $T$. It is invariant under a new Noether charge, $\Qbeta$. By explicit quantization, performed to order $\Tprime$ we show that the thermal vacuum is annihilated by $\Qbeta$, so that the new chiral symmetry is not broken spontaneously at high $T$. This high $T$ Noe

Ashoke Sen

Existence of SL(2,Z) duality in toroidally compactified heterotic string theory (or in the N=4 supersymmetric gauge theories), that includes the strong weak coupling duality transformation, implies the existence of certain supersymmetric bound states of monopoles and dyons. We show that the existence of these bound states, in turn, requires the existence of

I. E. Aronov, M. Jonson, A. M. Zagoskin

We present a theory for the nonlinear current-voltage characteristics of a ballistic quantum constriction. Nonlinear features first develop because of above-barrier reflection from the potential profile, created by impurities in the vicinity of the constriction. The nonlinearity appears on a small voltage scale and makes it possible to determine distances be

Leonardo Castellani

The gauging of the q-Poincaré algebra of ref. hep-th 9312179 yields a non-commutative generalization of the Einstein-Cartan lagrangian. We prove its invariance under local q-Lorentz rotations and, up to a total derivative, under q-diffeomorphisms. The variations of the fields are given by their q-Lie derivative, in analogy with the q=1 case. The algebra of q

Yoav Peleg

We use the canonical quantization of spherically symetric dust universes, and calculate the expectation value of the quantized metric, $<Ψ|\hat{g}|Ψ>$. Though the classical solutions are singular, and the wave functions have no zero support on singular geometries, the expectation values are everywhere regular. For a quasi-classical (coherent) state, the metr

J. M. Figueroa-O&#39;Farrill, S. Stanciu

By a Sugawara construction we mean a generalized Virasoro construction in which the currents are primary fields of conformal weight one. For simple Lie algebras, this singles out the standard Sugawara construction out of all the solutions to the Virasoro master equation. Examples of nonsemisimple Sugawara constructions have appeared recently. They share the

S. Randjbar-Daemi, J. Strathdee

A class of generalized Ising models is examined with a view to extracting a low energy sector comprising Dirac fermions coupled to Yang-Mills vectors. The main feature of this approach is a set of gap equations, covariant with respect to one of the $4$-dimensional crystallographic space groups.

R. Foot

We examine a $SU(3)_c \otimes SU(3)_{L}\otimes U(1)$ gauge model which has a parity symmetric Lagrangian. The parity symmetry has the novel feature that it interchanges the gluons with the $SU(3)_L$ gauge bosons (which contain the ordinary $SU(2)_L$ weak gauge bosons). We show that the model reduces to the standard model at low energies and also predicts new

Robert Foot, Hoang Ngoc Long, Tuan A. Tran

Pisano and Pleitez have introduced an interesting $\mbox{SU}(3)_C \otimes \mbox{SU}(3)_L \otimes \mbox{U}(1)_N$ gauge model which has the property that gauge anomaly cancellation requires the number of generations to be a multiple of 3. We consider generalizing that model to incorporate right-handed neutrinos. We find that there exists a non-trivial generali

R. Foot

Koide has pointed out that the mass relation $m_e + m_μ + m_τ = {2 \over 3}(\sqrt{m_e} + \sqrt{m_μ} + \sqrt{m_τ})^2 $ is consistent with the most recent measurements of the tau lepton mass. We point out that this relation has a geometric interpretation.

R. Foot

We re-examine neutrino oscillations in exact parity models. Previously it was shown in a specific model that large neutrino mixing angles result. We show here that this is a general result of neutrino mixing in exact parity models provided that the neutrino mass matrix is real. In this case, the effects of neutrino mixing in exact parity models is such that

R. Foot

In gauge theories like the standard model, the electric charges of the fermions can be heavily constrained from the classical structure of the theory and from the cancellation of anomalies. We argue that the anomaly conditions are not quite as well motivated as the classical constraints, since it is possible that new fermions could exist which cancel potenti

R. Foot, Tran Anh Tuan

We hypothesise that all electroweak symmetry breaking terms such as fermion masses and the W and Z gauge boson masses arise radiatively from just one explicit symmetry breaking term in the Lagrangian. Our hypothesis is motivated by the lack of experimental support and the lack of predictivity of the standard symmetry breaking scenario. We construct a simple

Scott Thomas

The Schiff moment, $\smij$, is a parity and time reversal violating fermion-fermion coupling. The nucleus-electron Schiff moment generically gives the most important contribution to the electric dipole moments of atoms and molecules with zero net intrinsic electronic spin and nuclear spin ${1 \over 2}$. Here, the electromagnetic contribution to the Schiff mo

Yu. L. Kalinovsky, C. Weiss

Heavy--light mesons are described in an effective quark theory with a two--body vector--type interaction. The bilocal interaction is taken to be instantaneous in the rest frame of the bound state, but formulated covariantly through the use of a boost vector. The chiral symmetry of the light flavor is broken spontaneously at mean field level. The framework fo

Oleg A. Fonarev

We study conformal properties of the quantum kinetic equations in curved spacetime. A transformation law for the covariant Wigner function under conformal transformations of a spacetime is derived by using the formalism of tangent bundles. The conformal invariance of the quantum corrected Vlasov equation is proven. This provides a basis for generating new so

Michael C. Martin, Xiaoqun Du, John Kwon, L. Mihaly

We report the measurement of infrared transmission of large C60 single crystals. The spectra exhibit a very rich structure with over 180 vibrational absorptions visible in the 100 - 4000 cm-1 range. Many silent modes are observed to have become weakly IR-active. We also observe a large number of higher order combination modes. The temperature (77K - 300K) an

A. M. Zagoskin, R. I. Shekhter

We show that the coherent mixing of different transverse modes, due to forward scattering of carriers by soft impurity- or boundary potentials leads to a nonlinear, asymmetric current response of quantum point contacts (QPC). The oscillating contribution to the current is sensitive both to driving voltage and to gate voltage in direct analogy to the electros

P. D. Coddington, L. Han

Standard Monte Carlo cluster algorithms have proven to be very effective for many different spin models, however they fail for frustrated spin systems. Recently a generalized cluster algorithm was introduced that works extremely well for the fully frustrated Ising model on a square lattice, by placing bonds between sites based on information from plaquettes