February 1997 arXiv papers — page 2

Tom O'Hara, Janyce Wiebe, Karen Payne

Human annotation of natural language facilitates standardized evaluation of natural language processing systems and supports automated feature extraction. This document consists of instructions for annotating the temporal information in scheduling dialogs, dialogs in which the participants schedule a meeting with one another. Task-oriented dialogs, such as t

Janna J. Levin, John D. Barrow, Emory F. Bunn, Joseph Silk

We investigate the behaviour of light rays in an open universe with a partly periodic horn topology. The geodesics can be solved exactly and the periodic topology creates characteristic new effects in temperature maps of the microwave background. Large flat regions appear in COBE sky maps even when multiple images of astronomical sources are unobservable.

David W. Hogg, Michael A. Pahre, James K. McCarthy, Judith G. Cohen

Ground-based counts and colors of faint galaxies in the U and R bands in one field at high Galactic latitude are presented. Integrated over flux, a total of 1.2x10^5 sources per square degree are found to U=25.5 mag and 6.3x10^5 sources per square degree to R=27 mag, with d log N/dm ~ 0.5 in the U band and d log N/dm ~ 0.3 in the R band. Consistent with thes

Grant Bazán, David Arnett

By direct hydrodynamic simulation, using the Piecewise Parabolic Method (PPM) code PROMETHEUS, we study the properties of a convective oxygen burning shell in a SN 1987A progenitor star prior to collapse. The convection is too heterogeneous and dynamic to be well approximated by one-dimensional diffusion-like algorithms which have previously been used for th

A. B. Henriques, L. E. Mendes, R. G. Moorhouse

This paper evaluates and compares the gravitational wave and density perturbation contributions to the cosmic microwave background radiation, on the basis of the same power law inflationary model. The inflation to radiation transition is treated as instantaneous, but a model is constructed to allow for a smooth transition from the radiation to the matter dom

R. D. Blum, T. M. Ramond, P. S. Conti, D. F. Figer

We present a new spectroscopic classification for OB stars based on H-band (1.5 micron to 1.8 micron) observations of a sample of stars with optical spectral types. Our initial sample of nine stars demonstrates that the combination of He I 1.7002 micron and H Brackett series absorption can be used to determine spectral types for stars between about O4 and B7

Fernando Atrio-Barandela, Sacha Davidson

We discuss the viability of a light particle ($\sim 30$ eV neutrino) with strong self-interactions as a dark matter candidate. The interaction prevents the neutrinos from free-streaming during the radiation dominated regime so galaxy sized density perturbations can survive. Smaller scale perturbations are damped due to neutrino diffusion. We calculate the po

Hyron Spinrad, Arjun Dey, Daniel Stern, James Dunlop

The weak radio source LBDS 53W091 is associated with a very faint (R approx. 24.5) red (R-K approx. 5.8) galaxy. Long spectroscopic integrations with the W. M. Keck telescope have provided an absorption-line redshift, z=1.552 +/- 0.002. The galaxy has a rest frame ultraviolet spectrum very similar to that of an F6V star, and a single-burst old stellar popula

Alan H. Durfee

This survey paper discusses five equivalent ways of defining a ``critical point at infinity'' for a complex polynomial of two variables.

Masako Furuya

Hypersurface simple K3 singularities defined by nondegenerate quasi-homogeneous polynomials are classified into ninety five classes in term of the weight of the polynomial by T. Yonemura. We consider versal deformations of them. It has been conjectured that the stratum $μ$ =const of the versal deformation of any nondegenerate hypersurface simple K3 singulari

J. Bunn, R. Foot, R. R. Volkas

The minimal interpretation of the atmospheric neutrino data suggests that the muon neutrino oscillates into another species with a mixing angle close to the maximal $π/4$. In the Exact Parity Symmetric Model, both the muon and electron neutrinos are expected to be maximally mixed with essentially sterile partners ($ν'_μ$ and $ν'_e$ respectively). We

Z. Bern, J. S. Rozowsky, B. Yan

Using cutting techniques we obtain the two-loop N=4 super-Yang-Mills helicity amplitudes for four-gluon scattering in terms of scalar integral functions. The N=4 amplitudes are considerably simpler than corresponding QCD amplitudes and therefore provide a testing ground for exploring two-loop amplitudes. The amplitudes are constructed directly in terms of ga

Ji-Min Duan

In a recent Letter (Phys. Rev. Lett.78, 1552 (1997) ), Zaikin, Golubev, van Otterlo, and Zimanyi criticized the phenomenological time-dependent Ginzburg-Laudau model which I used to study the quantum phase-slippage rate for superconducting wires. They claimed that they developed a "microscopic" model, made qualitative improvement on my overestimate o

Enrico Meggiolaro

It is known that the high-energy quark-quark scattering amplitude can be described by the expectation value of two lightlike Wilson lines, running along the classical trajectories of the two colliding particles. Generalizing the results of a previous paper, we give here the general proof that the expectation value of two infinite Wilson lines, forming a cert

Xin Xue, Haiqing Wei

The construction of a universal static quantum computer actually provides another proof of the NP-hardness of spin-glass problems.

A. P. Balachandran

Any two infinite-dimensional (separable) Hilbert spaces are unitarily isomorphic. The sets of all their self-adjoint operators are also therefore unitarily equivalent. Thus if all self-adjoint operators can be observed, and if there is no further major axiom in quantum physics than those formulated for example in Dirac's `Quantum Mechanics', then a q

Anzhong Wang, J. F. Villas da Rocha, N. O. Santos

Several classes of conformally-flat and spherically symmetric exact solutions to the Einstein field equations coupled with either a massless scalar field or a radiation fluid are given, and their main properties are studied. It is found that some represent the formation of black holes due to the gravitational collapse of the matter fields. When the spacetime

M. Gürtler, E. -M. Ilgenfritz, A. Schiller

We measure the interface tension near the phase transition endpoint of the 3d SU(2)-Higgs model. The tunnel correlation length method is used and compared to other approaches. A modified scaling behaviour for the mass gap as function of the transverse area is proposed.

Harold Widom

In previous work the author found solutions to the Toda equations that were expressed in terms of determinants of integral operators. Here it is observed that a simple variant yields solutions to the matrix Toda equations. As an application another derivation is given of a differential equation of Sato, Miwa and Jimbo for a particular Fredholm determinant.

William H. Kinney

I describe a general approach to characterizing cosmological inflation outside the standard slow-roll approximation, based on the Hamilton-Jacobi formulation of scalar field dynamics. The basic idea is to view the equation of state of the scalar field matter as the fundamental dynamical variable, as opposed to the field value or the expansion rate. I discuss

Haiqing Wei, Xin Xue

A new type of quantum simulator is proposed which can simulate any quantum many-body system in an isomorphic manner. It can actually synthesize a duplicate of the system to be simulated. The isomorphic simulation has the great advantage that the inevitable coupling of the simulator to the environment can be fully exploited in simulating thermodynamic process

Tom Banks, Nathan Seiberg

We identify Type IIA and IIB strings, as excitations in the matrix model of M theory.

Peter Schupp

Superconducting quantum symmetries in extended single-band 1-dimensional Hubbard models are shown to originate from the classical (pseudo-)spin SO(4) symmetry of a class of models of which the standard Hubbard model is a special case. Extending the notion of symmetry to include quantum groups allows us to introduce extra parameters but the corresponding quan

Ruth Durrer, Tina Kahniashvili

Anisotropies in the cosmic microwave background radiation due to gravity waves are investigated. An initial spectrum of gravity waves may have been induced during an epoch of inflation. We study the propagation of such a spectrum in a Friedmann background of hot and cold dark matter, radiation and (possibly) a cosmological constant. We finally calculate its

Subhendra Mohanty

We perform a covariant wavepacket analysis of neutrino oscillations taking into account the lifetime of the neutrino production process . We find that flavour oscillations in space are washed out when the neutrinos are produced from long lived resonances - and what may be observed in appearance/disappearance experiments is a uniform conversion probability in

A. Nicolaidis, J. E. Paschalis, P. I. Porfyriadis

The origin of the string conformal anomaly is studied in detail. We use a reformulated string Lagrangian which allows to consider the string tension $T_{0}$ as a small perturbation. The expansion parameter is the worldsheet speed of light c, which is proportional to $T_{0}$ . We examine carefully the interplay between a null (tensionless) string and a tensio

Mihir P. Worah

We study the possibility of baryogenesis in the case of supersymmetry breaking with large mixing between the right-handed scalar charm and right-handed scalar top or right-handed scalar up and right-handed scalar top squarks resulting in one light right-handed up-type squark mass eigenstate. We argue that in this case the electroweak phase transition will be

Neal J. Fowler

We characterize the state space of a Toeplitz-Cuntz algebra TO_n in terms of positive operator matrices $Ω$ on Fock space which satisfy sl(Ω) \le Ω, where sl(Ω) is the operator matrix obtained from Ωby taking the trace in the last variable. Essential states correspond to those matrices Ωwhich are slice-invariant. As an application we show that a pure essenti

Emanuel Knill, Raymond Laflamme, Wojciech H. Zurek

Recent research has demonstrated that quantum computers can solve certain types of problems substantially faster than the known classical algorithms. These problems include factoring integers and certain physics simulations. Practical quantum computation requires overcoming the problems of environmental noise and operational errors, problems which appear to

Philip Maymin

We show that the lambda-q calculus can efficiently simulate quantum Turing machines by showing how the lambda-q calculus can efficiently simulate a class of quantum cellular automaton that are equivalent to quantum Turing machines. We conclude by noting that the lambda-q calculus may be strictly stronger than quantum computers because NP-complete problems su

F. Ghaboussi

The canonical quantization of flux is performed. It is shown that according to the canonical flux quantization there must be a new uncertainty relation: $e ΔA_m . Δx_m \geq \hbar$ where $A_m$ and $Δx_m \geq l_B$ are the electromagnetic gauge potential, the position uncertainty and the magnetic length, respectively. Other arguments in favour of this uncertain

P. Duclos, P. Stovicek, M. Vittot

We study a perturbed Floquet Hamiltonian $K+βV$ depending on a coupling constant $β$. The spectrum $σ(K)$ is assumed to be pure point and dense. We pick up an eigen-value, namely $0\inσ(K)$, and show the existence of a function $λ(β)$ defined on $I\subset\R$ such that $λ(β) \in σ(K+βV)$ for all $β\in I$, 0 is a point of density for the set $I$, and the Rayle

L. Lanz, B. Vacchini

The meaning of statistical experiments with single microsystems in quantum mechanics is discussed and a general model in the framework of non-relativistic quantum field theory is proposed, to describe both coherent and incoherent interaction of a single microsystem with matter. Compactly developing the calculations with superoperators, it is shown that the i

Howard Barnum, M. A. Nielsen, Benjamin Schumacher

Noisy quantum channels may be used in many information carrying applications. We show that different applications may result in different channel capacities. Upper bounds on several of these capacities are proved. These bounds are based on the coherent information, which plays a role in quantum information theory analogous to that played by the mutual inform

Ennio Gozzi

In this paper we review the recently proposed path-integral counterpart of the Koopman-von Neumann operatorial approach to classical Hamiltonian mechanics. We identify in particular the geometrical variables entering this formulation and show that they are essentially a basis of the cotangent bundle to the tangent bundle to phase-space. In this space we intr

B. Mueller, D. H. Beck, E. J. Beise, E. Candell

We report the first measurement of the parity-violating asymmetry in elastic electron scattering from the proton. The asymmetry depends on the neutral weak magnetic form factor of the proton which contains new information on the contribution of strange quark-antiquark pairs to the magnetic moment of the proton. We obtain the value $G_M^Z= 0.34 \pm 0.09 \pm 0

Hans Schoutens

Let K be an algebraically closed field endowed with a complete non-archimedean norm. Let f:Y -> X be a map of K-affinoid varieties. We prove that for each point x in X, either f is flat at x, or there exists, at least locally around x, a maximal locally closed analytic subvariety Z in X containing x, such that the base change f^{-1}(Z) -> Z is flat at x, and

Sakae Fuchino

We introduce several new set-theoretic axioms formulated in terms of coloring of ordinals by reals. We show that these axioms generalize the axioms considered by I.Juhasz, L.Soukup and Z.Szentmiklossy, and give a class of p.o.s including Cohen p.o.-sets which force the axioms. In appearance these axioms are somewhat similar to OCA but it appears that they ar

V. Fateev, S. Lukyanov, A. Zamolodchikov, Al. Zamolodchikov

We propose an explicit expression for vacuum expectation values of the boundary field e^{iaϕ_{B}} in the boundary sine-Gordon model with zero bulk mass. This expression agrees with known exact results for the boundary free energy and with perturbative calculations.

Gianfranco Pradisi

The parameter-space orbifold construction of open and unoriented toroidal and (target-space) orbifold compactifications is briefly reviewed, with emphasis on the underlying geometrical framework. A class of chiral four-dimensional type-I vacua with three generations is also discussed.

J. Ambjorn, M. G. Harris, M. Weis

We discuss how concepts such as geodesic length and the volume of space-time can appear in 2d topological gravity. We then construct a detailed mapping between the reduced Hermitian matrix model and 2d topological gravity at genus zero. This leads to a complete solution of the counting problem for planar graphs with vertices of even coordination number. The

S. Deser, A. Gomberoff, M. Henneaux, C. Teitelboim

We investigate duality properties of N-form fields, provide a symmetric way of coupling them to electric/magnetic sources, and check that these charges obey the appropriate quantization requirements. First, we contrast the D=4k case, in which duality is a well-defined SO(2) rotation generated by a Chern-Simons form leaving the action invariant, and D=4k+2 wh

Harry W. Braden, Ryu Sasaki

We seek to clarify some of the physical aspects of the Ruijsenaars-Schneider models. This important class of models was presented as a relativistic generalisation of the Calogero-Moser models but, as we shall argue, this description is misleading. It is far better to simply view the models as a one-parameter generalisation of Calogero-Moser models. By viewin

Hirosi Ooguri, Cumrun Vafa

We discuss how N=1 dualities in four dimensions are geometrically realized by wrapping D-branes about 3-cycles of Calabi-Yau threefolds. In this setup the N=1 dualities for SU, SO and USp gauge groups with fundamental fields get mapped to statements about the monodromy and relations among 3-cycles of Calabi-Yau threefolds. The connection between the theory a

A. Arhrib, A. Djouadi, W. Hollik, C. Junger

In supersymmetric theories, the decays of the neutral CP-even and CP-odd as well as the charged Higgs bosons into scalar quarks, in particular into top and bottom squarks, can be dominant if they are kinematically allowed. We calculate the QCD corrections to these decay modes in the minimal supersymmetric extension of the Standard Model, including all quark

Michihiro Hirata, Naoto Tsutsui

We construct a phenomenological model which describes the dynamical chiral symmetry breaking (DCSB) of QCD vacuum and reproduces meson spectra. Quark condensates, the pion decay constant, and meson spectra are well reproduced by phenomenological interaction which consists of a linear confining potential, a Coulombic potential, and the 't Hooft determinan

Stephen M. Ouellette, Ryoichi Seki

We calculate, in chiral perturbation theory, the change in the self-energy of decuplet baryons in nuclear matter. These self-energy shifts are relevant in studies of meson-nucleus scattering and of neutron stars. Our results are leading order in an expansion in powers of the ratio of characteristic momenta to the chiral symmetry-breaking scale (or the nucleo

Orfeu Bertolami

In this lecture we address the following issues in the context of string theories: i) The role played by S and T dualities in obtaining topological inflation in N=1 supergravity models, ii) A mechanism to generate the baryon asymmetry of the Universe based on the string interactions that violate CPT symmetry and iii) The quantum cosmology of the dimensionall

T. Hjelt, I. Vattulainen, J. Merikoski, T. Ala-Nissila

We present a combined analytical and numerical approach based on the Mori projection operator formalism and Monte Carlo simulations to study surface diffusion within the lattice-gas model. In the present theory, the average jump rate and the susceptibility factor appearing are evaluated through Monte Carlo simulations, while the memory functions are approxim

J. Ashkenazi

The electronic structure of the high-Tc cuprates is studied in terms of "large-U" and "small-U" orbitals. A striped structure and three types of quasiparticles are obtained, polaron-like "stripons" carrying charge, "svivons" carrying spin, and "quasielectrons" carrying both. The anomalous properties are explained, and

Indrani Bose, Indranath Chaudhuri

We study the effect of randomness and anisotropy on Turing patterns in reaction-diffusion systems. For this purpose, the Gierer-Meinhardt model of pattern formation is considered. The cases we study are: (i)randomness in the underlying lattice structure, (ii)the case in which there is a probablity p that at a lattice site both reaction and diffusion occur, o

D. V. Livanov, A. A. Varlamov, F. Federici

We study the effect of the density of states (DOS) fluctuations on the thermoelectric coefficient of superconductor above critical temperature. It is shown that in the isotropic case it is the DOS contribution which gives rise to the leading correction to thermoelectric coefficient in spite of previous results where the only Aslamazov-Larkin term was taken i

Gerald Bedürftig, Holger Frahm

We use the Bethe Ansatz solution for the one dimensional Hubbard model with open boundary conditions and applied boundary fields to study the spectrum of bound states at the boundary. Depending on the strength of the boundary potentials one finds that the true ground state contains a single charge or, for boundary potentials comparable to the Hubbard interac

P. E. Kornilovitch, E. R. Pike

A new Monte Carlo algorithm for calculating polaron effective mass is proposed. It is based on the path-integral representation of a partial partition function with fixed total quasi-momentum. Phonon degrees of freedom are integrated out analytically resulting in a single-electron system with retarded self-interaction and open boundary conditions in imaginar

P. Sitko, J. J. Quinn, D. C. Marinescu

Within the newly formulated composite fermion hierarchy the filling fraction of a spherical quantum Hall system is obtained when it can be expressed as an odd or even denominator fraction. A plot of $ν\frac{2S}{N-1}$ as a function of $2S$ for a constant number of particles (up to N=10001) exhibits structure of the fractional quantum Hall effect. It is confir

Omri Gat, Zeev Olami

We study the high-dimensional properties of an invading front in a disordered medium with random pinning forces. We concentrate on interfaces described by bounded slope models belonging to the quenched KPZ universality class. We find a number of qualitative transitions in the behavior of the invasion process as dimensionality increases. In low dimensions $d<

H. Donnerberg, S. Toebben, A. Birkholz

Defect electrons (holes) play an important role in most technologically important complex oxides; many of which possess perovskite-related structures. In this contribution we present the first detailed characterization of localized hole states in such materials. Our investigations employ advanced embedded-cluster calculations which consistently include elect

Satoshi Fujimoto, Norio Kawakami

Low-energy properties of the one-dimensional Kondo lattice model are investigated by using bosonization and renormalization group methods. The formation of the spin and charge excitation gaps at half-filling is discussed in detail both for antiferromagnetic and ferromagnetic Kondo couplings. Also, the effect of the interaction between conduction electrons on

R. Eder, Y. Ohta

We present an exact diagonalization study of the single particle spectral function in the 1D and 2D t-J model. By studying the scaling properties with J and t we find a simple building pattern in 1D and show that every spectral feature can be uniquely assigned by a spinon and holon momentum. We find two types of low energy excitations: a band with energy sca

Hermann Schulz-Baldes

A generalization of the Drude model is studied. On the one hand, the free motion of the particles is allowed to be sub- or superdiffusive; on the other hand, the distribution of the time delay between collisions is allowed to have a long tail and even a non-vanishing first moment. The collision averaged motion is either regular diffusive or Lévy-flight like.

N. Taniguchi

By utilizing the symmetric property known as the Ward-Takahashi identity in disordered systems, we explore the novel symmetry relations which hold in one-dimensional systems with inverse square interaction (the Calogero-Sutherland model). The identities emerge totally from the algebraic structure of the model. They show that the dynamical correlators are con

Marilyn A. Walker, Janet E. Cahn, Stephen J. Whittaker

This paper introduces Linguistic Style Improvisation, a theory and set of algorithms for improvisation of spoken utterances by artificial agents, with applications to interactive story and dialogue systems. We argue that linguistic style is a key aspect of character, and show how speech act representations common in AI can provide abstract representations fr

R. E. Pudritz, D. E. McLaughlin, R. Ouyed

Observational advances over the last decade reveal that star formation is associated with the simultaneous presence of gravitationally collapsing gas, bipolar outflow, and an accretion disk. Two theoretical views of star formation suppose that either stellar mass is determined from the outset by gravitational instability, or by the outflow which sweeps away

Enrique Martinez-Gonzalez, Jose L. Sanz, Laura Cayon

We have studied the effect of gravitational lensing on the Cosmic Microwave Background (CMB) anisotropy in flat and open universes. We develop a formalism to calculate the changes on the radiation power spectrum induced by lensing in the Newtonian and synchronous-comoving gauges. The previously considered negligible contribution to the CMB radiation power sp

Ulrich Hopp

Two surveys for intrinsically faint galaxies towards nearby voids have been conducted at the MPI für Astronomie, Heidelberg. One selected targets from a new diameter limited ($Φ\ge 5&#39;&#39;$) catalog with morphological criteria while the other used digitized objective prism Schmidt plates to select mainly HII dwarf galaxies. For some 450 galaxies, redshif

Zhiyu Guo, David N. Burrows

We present the results of our ASCA SIS and GIS observations of the supernova remnant VRO42.05.01. Our spectral fits indicate that the SNR is isothermal (about 8.3 X 10^6 K), consistent with our ROSAT analysis results. The absorbing column density (about 2.9 X 10^21 cm^-2) obtained from these spectral fits is much smaller than expected for the nominal distanc

A. Ratcliffe, T. Shanks, R. Fong, Q. A. Parker

We have investigated the redshift space distortions in the optically selected Durham/UKST Galaxy Redshift Survey using the 2-point galaxy correlation function perpendicular and parallel to the observer&#39;s line of sight. We present results for the real space 2-point correlation function, by inverting the optimally estimated projected correlation function a

A. Ratcliffe, T. Shanks, Q. A. Parker, R. Fong

We have investigated the statistical clustering properties of galaxies by calculating the 2-point galaxy correlation function from the Durham/UKST Galaxy Redshift Survey. This survey is magnitude limited to bj = 17, contains 2500 galaxies sampled at a rate of one in three and surveys a 4 \times 10^6 (h^-1Mpc)^3 volume of space. We have empirically determined

Guillaume Hébrard, Martin Lemoine, Roger Ferlet, Alfred Vidal-Madjar

We present the results of observations of the $λ3130.4$ Åinterstellar absorption line of Be II in the direction of zeta Per. The data were obtained at the Canada-France-Hawaii 3.6m Telescope using the Coudé f/4 Gecko spectrograph at a resolving power $\simeq 1.1 \times 10^5$, and a signal-to-noise ratio S/N $\simeq$ 2000. The Be II line is not detected, and

W. L. Holzapfel, M. Arnaud, P. A. R. Ade, S. E. Church

We report 2.1 mm observations of the Sunyaev-Zel&#39;dovich (S-Z) effect; these observations confirm our previous detection of a decrement in the Cosmic Microwave Background intensity towards the cluster Abell 2163. The S-Z data are analyzed using the relativistically correct expression for the Comptonization. We begin by assuming the intracluster (IC) gas t

W. L. Holzapfel, P. A. R. Ade, S. E. Church, P. D. Mauskopf

We report millimeter-wavelength observations of the Sunyaev-Zel&#39;dovich (S-Z) effect in two distant galaxy clusters. A relativistically correct analysis of the S-Z data is combined with the results of X-ray observations to determine the radial peculiar velocities v_r of the clusters. We observed Abell 2163 (z=.201) in three mm-wavelength bands centered at

W. L. Holzapfel, T. M. Wilbanks, P. A. R. Ade, S. E. Church

Measurements of the Sunyaev-Zel&#39;dovich (S-Z) effect towards distant clusters of galaxies can be used to determine the Hubble constant and the radial component of cluster peculiar velocities. Determination of the cluster peculiar velocity requires the separation of the two components of the S-Z effect, which are due to the thermal and bulk velocities of t

Mina Teicher

This paper will appear in the Santa Cruz proceedings. An overview of the braid group techniques in the theory of algebraic surfaces, from Zariski to the latest results, is presented. An outline of the Van Kampen algorithm for computing fundamental groups of complements of curves and the modification of Moishezon-Teicher regarding branch curves of generic pro

A. Kovner, M. Shifman

We argue that supersymmetric gluodynamics (theory of gluons and gluinos) has a condensate-free phase. Unlike the standard phase, the discrete axial symmetry of the Lagrangian is unbroken in this phase, and the gluino condensate does not develop. Extra unconventional vacua are supersymmetric and are characterized by the presence of (bosonic and fermionic) mas

Yuval Grossman, Howard E. Haber

In any model with nonzero Majorana neutrino masses, the sneutrino and antisneutrino of the supersymmetric extended theory mix. We outline the conditions under which sneutrino-antisneutrino mixing is experimentally observable. The mass-splitting of the sneutrino mass eigenstates and sneutrino oscillation phenomena are considered.

ZEUS Collaboration, Breitweg et al

Using the ZEUS detector at HERA, we have studied the reaction e^+ p -> e^+ X for Q^2 > 5000 GeV^2 with a 20.1 pb^{-1} data sample collected during the years 1994 to 1996. For Q^2 below 15000 GeV^2, the data are in good agreement with Standard Model expectations. For Q^2 > 35000 Gev^2, two events are observed while 0.145+-0.013 events are expected. A statisti

T. P. Branson, P. B. Gilkey, D. V. Vassilevich

Let M be a compact Riemannian manifold with smooth boundary. We study the vacuum expectation value of an operator Q by studying Tr Qe^{-tD}, where D is an operator of Laplace type on M, and where Q is a second order operator with scalar leading symbol; we impose Dirichlet or modified Neumann boundary conditions.

Hector Giacomini, Sebastien Neukirch

In this paper, we consider three-dimensional dynamical systems, as for example the Lorenz model. For these systems, we introduce a method for obtaining families of two-dimensional surfaces such that trajectories cross each surface of the family in the same direction. For obtaining these surfaces, we are guided by the integrals of motion that exist for partic

M. Novello, V. A. De Lorenci, E. Elbaz

We claim that the existence of a mechanism such that photons may be trapped in a compact domain is not an exclusive property of gravitational forces. We show the case in which a non-linear electrodynamics allows such effect. In this latter case we should call this region an Electromagnetic Black Hole (EBH).

A. E. Dorokhov, S. V. Esaibegyan, S. V. Mikhailov

We calculate the lowest-dimensional nonlocal quark and gluon condensates within the single instanton approximation of the instanton liquid model. As a result, we determine the values of average virtualities of quarks $λ_q^2$ and gluons $λ_g^2$ in the QCD vacuum and obtain parameterless predictions for the ratio $λ_g^2/λ_q^2 = 12/5$, and for some ratios of di

R. S. Chivukula, B. A. Dobrescu, E. H. Simmons

The triviality of the scalar sector of the standard one-doublet Higgs model implies that this model is only an effective low-energy theory valid below some cut-off scale $Λ$. The underlying high-energy theory must include flavor dynamics at a scale of order $Λ$ or greater in order to give rise to the different Yukawa couplings of the Higgs to ordinary fermio

Michel Dubois-Violette, John Madore, Richard Kerner

We analyse the structure of the $κ=0$ limit of a family of algebras $A_κ$ describing noncommutative versions of space-time, with $κ$ a parameter of noncommutativity. Assuming the Poincaré covariance of the $κ=0$ limit, we show that, besides the algebra of functions on Minkowski space, $A_0$ must contain a nontrivial extra factor $A^I_0$ which is Lorentz cova

Miles Reid

This is a rough write-up of my lecture at Kinosaki and two lectures at RIMS workshops in Dec 1996, on work in progress that has not yet reached any really worthwhile conclusion, but contains lots of fun calculations. History of Vafa&#39;s formula, how the McKay correspondence for finite subgroups of SL(n,C) relates to mirror symmetry. The main aim is to give

K. Huitu, P. N. Pandita, K. Puolamäki

We obtain a relation between right-handed gauge boson mass and soft squark mass in naturally R-parity conserving general supersymmetric left-right models. This relation implies that either ${W_R}$ is lighter than twice the soft squark mass, or a ratio of vacuum expectation values (VEVs) in the model, denoted by $\tanα$, is close to its value of unity in the

E. Gabrielli, V. A. Ilyin, B. Mele

One-loop production of a Higgs boson in electro-photon collisions at future accelerators is studied via the process (e gamma -> e H), for intermediate Higgs masses. Exact cross sections, including the possibility of longitudinally polarized initial beams, are presented. Confirming previous estimates made in the Weizsäcker-Williams approximation, they are fou

Kentaro Hori, Yaron Oz

We construct T-duality on K3 surfaces. The T-duality exchanges a 4-brane R-R charge and a 0-brane R-R charge. We study the action of the T-duality on the moduli space of 0-branes located at points of K3 and 4-branes wrapping it. We apply the construction to F-theory compactified on a Calabi-Yau 4-fold and study the duality of N=2 SU(N_c) gauge theories in fo

Max Tegmark

Some superstring theories have more than one effective low-energy limit, corresponding to classical spacetimes with different dimensionalities. We argue that all but the 3+1-dimensional one might correspond to ``dead worlds&#39;&#39;, devoid of observers, in which case all such ensemble theories would actually predict that we should find ourselves inhabiting

C. J. Burden

The renormalised quark Dyson-Schwinger equation is studied in the limit of the renormalised current heavy quark mass m_R --> infinity. We are particularly interested in the analytic pole structure of the heavy quark propagator in the complex momentum plane. Approximations in which the quark-gluon vertex is modelled by either the bare vertex or the Ball-Chiu

Riccardo Adami, Alessandro Teta

Using the theory of self-adjoint extensions, we construct all the possible hamiltonians describing the non relativistic Aharonov-Bohm effect. In general the resulting hamiltonians are not rotationally invariant so that the angular momentum is not a constant of motion. Using an explicit formula for the resolvent, we describe the spectrum and compute the gener

Angel Ballesteros, Mariano del Olmo

Lie algebra contractions on the classical Drinfel&#39;d Double of a given Lie bialgebra are introduced and compared to the usual Lie bialgebra contraction theory. The connection between both approaches turns out to be intimately linked to duality problems. The non-relativistic (Galilean) limit of a (1+1) Poincaré Double is used to illustrate the contraction

B. Feigin, M. Jimbo, T. Miwa, A. Odesskii

We construct a family of intertwining operators (screening operators) between various Fock space modules over the deformed $W_n$ algebra. They are given as integrals involving a product of screening currents and elliptic theta functions. We derive a set of quadratic relations among the screening operators, and use them to construct a Felder-type complex in t

Khaled Abdel-Khalek

We give a one dimensional octonionic representation of the different Clifford algebra $Cliff(5,5)\sim Cliff(1,9), Cliff(6,6)\sim Cliff(2,10)$ and lastly $Cliff(7,6)\sim Cliff(3,10)$.

Luis P. Chimento

Einstein equations for several matter sources in Robertson-Walker and Bianchi I type metrics, are shown to reduce to a kind of second order nonlinear ordinary differential equation $\ddot{y}+αf(y)\dot{y}+βf(y)\int{f(y) dy}+γf(y)=0$. Also, it appears in the generalized statistical mechanics for the most interesting value q=-1. The invariant form of this equat

Savely G. Karshenboim, Vladimir G. Ivanov

Radiative corrections to the decay rate in the low-Z hydrogen-like muonic atoms are considered. The correction arises from the Uehling potential and it has the relative order of alpha. The numerical results are reported for the 2p-1s transition for the atom with the nuclear charge value up to Z=10.

Savely G. Karshenboim, Vladimir G. Ivanov

Radiative corrections to the 2E1 decay width of the 2s-state in the low-Z hydrogen-like system are examined within logarithmic approximation. The correction is found to be 2.025(1) alpha (Z alpha)^2 / pi log(Z alpha)^2 in units of the non-relativistic rate.

R. L. Workman

We suggest that the error quoted in the Mainz determination of the E2/M1 ratio (at the resonance energy) should be enlarged. A term dropped in expressions used by this group could be significant.

R. C. Hwa, J. Pisut, N. Pisutova

The depletion of gluons as the parton flux traverses a nucleus in a heavy-ion collision can influence the production rate of heavy-quark states. Thus the suppression of $J/ψ$ can be due to gluon depletion in the initial state in addition to nuclear and hadronic absorption in the final state. A formalism is developed to describe the depletion effect. It is sh

B. Mosconi, P. Ricci

We study the deuteron electrodisintegration with inclusion of the neutral currents focusing on the helicity asymmetry of the exclusive cross section in coplanar geometry. We stress that a measurement of this asymmetry in the quasi elastic region is of interest for an experimental determination of the weak form factors of the nucleon, allowing one to obtain t

George Kahrimanis, George Burleson, C. M. Chen, B. C. Clark

Pion-nucleus elastic scattering at energies above the Delta(1232) resonance is studied using both pi+ and pi- beams on 12C, 40Ca, 90Zr, and 208Pb. The present data provide an opportunity to study the interaction of pions with nuclei at energies where second-order corrections to impulse approximation calculations should be small. The results are compared with

Narcisse Randrianantoanina

Let $A$ be a $C^*$-algebra. It is shown that every absolutely summing operator from $A$ into $\ell_2$ factors through a Hilbert space operator that belongs to the 4-Schatten- von Neumann class. We also provide finite dimensinal examples that show that one can not improve the 4-Schatten-von Neumann class to $p$-Schatten von Neumann class for any $p<4$. As app