August 1998 arXiv papers — page 16

Jerry Lodder

In this paper we continue the investigation of Loday's Leibniz cohomology as a new invariant for differentiable manifolds. In particular the Leibniz coboundary of a k-tensor (in the sense of differential geometry) is computed in a local coordinate chart and then interpreted in terms of the calculus of variations. For example, the Leibniz coboundary of th

Eric M. Opdam

We prove the Plancherel formula for hypergeometric functions associated to a root system in the situation when the root multiplicities are negative (but close to 0). As a result we obtain a classification of the hypergeometric functions that are square integrable, and we find a closed formula for their square norm as a function of the root multiplicities.

Do Ngoc Diep

We expose a K-theoretic approach to study group C*-algebras and C*-algebraic compact quantum groups: 1. The conception of multidimensional geometric quantization and the index of group C*-algebras; 2. the entire homology of noncommutative de Rham currents and the noncommutative Chern characters, and their computation for C*-algebras of compact Lie groups and

Lajos Molnar

We present an operator algebraic approach to Wigner's unitary-antiunitary theorem using some classical results from ring theory. To show how effective this approach is, we prove a generalization of this celebrated theorem for Hilbert modules over matrix algebras. We also present a Wigner-type result for maps on prime C*-algebras.

Martin Lorenz

We give a description of the kernel of the induction map K_0(R)->K_0(S), where S is a commutative ring and R is the ring of invariants of the action of a finite group G on S. The description is in terms of H^1(G,GL(S)).

H. Ahmedov, I. H. Duru

(2+2)-dimensional quantum mechanical q-phase space which is the semi-direct product of the quantum plane E_q(2)/U(1) and its dual algebra e_q(2)/u(1) is constructed. Commutation and the resulting uncertainty relations are studied. ``Quantum mechanical q-Hamiltonian'' of the motion over the quantum plane is derived and the solution of the Schroedinger

H. Ahmedov, I. H. Duru

Following the construction of the invariant integral and the scalar product for the quantum Euclidean group E_q(2), we obtained the full matrix elements of its unitary irreducible representations from SU_q(2) by contraction and then derived the Planscherel measure.

Laurence R. Taylor

This paper classifies embedded, codimension-one spheres which are null homotopic. This information is used to show that all null homotopic, immersed codimension-one spheres which are taut in the sense of Terng and Thorbergsson are actually distance spheres.

R. Jackiw, So-Young Pi

We consider models in which nonrelativistic matter fields interact with gauge fields whose dynamics are governed by the Chern-Simons term. The relevant equations of motion are derived and reduced dimensionally in time or in space. Interesting solitonic equations emerge and their solutions are described. Finally, we consider a Chern-Simons term in three-dimen

D. Minic

In this note further evidence is collected in support of the claim that the space-time uncertainty principle implies holography, both within the context of Matrix Theory and the framework of the proposed duality between certain conformal field theories and M-theory/string theory on AdS backgrounds.

Hideaki Aoyama, Hisashi Kikuchi, Ikuo Okouchi, Masatoshi Sato

The elucidation of the properties of the instantons in the topologically trivial sector has been a long-standing puzzle. Here we claim that the properties can be summarized in terms of the geometrical structure in the configuration space, the valley. The evidence for this claim is presented in various ways. The conventional perturbation theory and the non-pe

George Chapline, Alex Granik

An elementary introduction is provided to the phase space quantization method of Moyal and Wigner. We generalize the method so that it applies to 2-dimensional surfaces, where it has an interesting connection with quantum holography. In the case of Riemann surfaces the connection between Moyal quantization and holography provides new insights into the Torell

Alex Kovner, Baruch Rosenstein

We consider properties of confining strings in 2+1 dimensional SU(2) nonabelian gauge theory with the Higgs field in adjoint representation. The analysis is carried out in the context of effective dual Lagrangian which describes the dynamics of t'Hooft's $Z_{N}$ vorices. We point out that the same Lagrangian should be interpreted as an effective Lagrangian f

Fred J. Browning, Darwin Chang, Wai-Yee Keung

We calculate the width difference of the scalar electron decay, $Γ(\tilde e_L \to e_Lω) - Γ({\bar{\tilde e}}_L \to \bar e_Lω)$ in the softly broken supersymmetrized standard model. The CP asymmetry is assumed to arise from the complex gaugino masses. Even in limit that the electron mass $m_e$ is vanishing, the difference can be of the order of $α$.

J. Ellis, G. K. Leontaris, S. Lola, D. V. Nanopoulos

Motivated by the Super-Kamiokande atmospheric neutrino data, we discuss possible textures for Majorana and Dirac neutrino masses within the see-saw framework. The main purposes of this paper are twofold: first to obtain intuition from a purely phenomenological analysis, and secondly to explore to what extent it may be realized in a specific model. We comment

E. Leader, A. V. Sidorov, D. B. Stamenov

We study the effect of scheme dependence upon the NLO QCD analysis of the world data on polarized DIS. The reliability of an analysis at NLO is demonstrated by the consistency of our polarized densities with the NLO transformation rules relating them to each other. We stress the importance of the chiral JET scheme in which all the hard effects are consistent

B. Magradze

The structure of the beta function of massless QCD is considered in analytic perturbation theory (APT). The two-loop analytic effective coupling is written in terms of the Lambert W function. The method of APT is applied to the gluon propagator in the Landau gauge. It is shown that there is an nonperturbative ambiguity in determination of the anomalous dimen

M. V. Chistyakov, A. V. Kuznetsov, N. V. Mikheev

The photon-neutrino process gamma gamma -> nu bar nu and photon splitting are considered in a strong magnetic field. The partial polarization amplitudes are calculated within the standard model in the limit of a strong field. The amplitudes do not depend on the field strength in this limit. Using the vector parts of the amplitudes, the process of the photon

R. Dick, N. Eschrich, M. Gaul

We point out that the spectrum and interactions of light states of the heterotic string indicate a string scale close to the GUT scale, and a mass generating scale for the gravitationally interacting states around 10^9 GeV if these states contribute a large fraction to dark matter.

J. Fleischer, A. V. Kotikov, O. L. Veretin

The method of the large mass expansion (LME) is investigated for selfenergy and vertex functions in two-loop order. It has the technical advantage that in many cases the expansion coefficients can be expressed analytically. As long as only one non-zero external momentum squared, $q^2$, is involved also the Taylor expansion (TE) w.r.t. small $q^2$ yields high

Kin-ya Oda, Eiichi Takasugi, Minoru Tanaka, Masaki Yoshimura

We discussed neutrino masses and mixings in SUSY SO(10) model where quarks and leptons have Yukawa couplings to at least two 10 and one $\bar{126}$ Higgs scalars. In this model, the Dirac and the right-handed Majorana mass terms are expressed by linear combinations of quark and charged lepton mass matrices, which then determine the neutrino mass matrix by th

J. N. Capdevielle, J. Gawin, D. Sobczynska, B. Szabelska

An extensive simulation has been carried out to estimate the physical interpretation of dynamical factors such as <Rh>, <Eh x Rh> in terms of high energy interaction features, concentrated in the present analysis on the average transverse momentum. It appears that the large enhancement observed for <Eh x Rh> versus primary energy, suggesting in earliest anal

Robert Fleischer

The decays $B^\pm\to π^\pm K$ and $B_d\to π^\mp K^\pm$ were observed by the CLEO collaboration last year; they may play an important role to probe the angle $γ$ of the unitarity triangle of the CKM matrix. After a general parametrization of their decay amplitudes within the Standard Model, strategies to constrain and determine the CKM angle $γ$ with the help

Yu-Qi Chen

A new explanation for the longstanding puzzle of the tiny branching fraction of psi&#39; --> rho pi relative to that for J/psi --> rho pi was proposed. In the case of J/psi, we argue that this decay is dominated by a higher Fock state in which the c cbar pair is in a color-octet ^3S_1 state and annihilates via the process c cbar --> q qbar. In the case of th

A. Bucarelli, F. Palombi, R. Petronzio, A. Shindler

We define, within the Schroedinger functional scheme (SF), the matrix elements of the twist-2 operators corresponding to the first two moments of non-singlet parton densities. We perform a lattice one-loop calculation that fixes the relation between the SF scheme and other common schemes and shows the main source of lattice artefacts. This calculation sets t

B. Alles, M. D&#39;Elia, A. Di Giacomo, P. W. Stephenson

We investigate the topological properties of the QCD vacuum with 4 flavours of dynamical staggered fermions at finite temperature. To calculate the topological susceptibility we use the field-theoretical method. As in the quenched case, a sharp drop is observed for the topological susceptibility across the phase transition.

P. A. Movilla Fernández

Studies of event shape observables at PETRA and LEP energies are presented. Previously published determinations of the strong coupling constant α_s at \sqrt{s} = 35 and 44 GeV are complemented using new resummed QCD calculations for the C parameter and improved calculations for the jet broadening variables B_T and B_W which recently became available. Further

Jerzy Matyjasek

The renormalized expectation value of the stress energy tensor of the conformally invariant massless fields in the Unruh state in the Schwarzschild spacetime is constructed. It is achieved through solving the conservation equation in conformal space and utilizing the regularity conditions in the physical metric. The relations of obtained results to the exist

Takahiro Tanaka, Misao Sasaki

In the path integral approach to false vacuum decay with the effect of gravity, there is an unsolved problem, called the negative mode problem. We show that the appearance of a supercritical supercurvature mode in the one-bubble open inflation scenario is equivalent to the existence of a negative mode around the Euclidean bounce solution. Supercritical super

Alexander L. Fetter

A vortex in a trapped Bose-Einstein condensate can experience at least two types of instabilities. (1). Macroscopic hydrodynamic motion of the vortex core relative to the center of mass of the condensate requires some process to dissipate energy. (2). Microscopic small-amplitude normal modes can also induce an instability. In one specific example, the vortex

B. P. van Zyl, E. Zaremba

We have studied the collective plasma excitations of a two-dimensional electron gas with an arbitrary lateral charge-density modulation. The dynamics is formulated using a previously developed hydrodynamic theory based on the Thomas-Fermi-Dirac-von Weizsacker approximation. In this approach, both the equilibrium and dynamical properties of the periodically m

Yuriy Makhlin, Gerd Schoen, Alexander Shnirman

Low-capacitance Josephson junctions, where Cooper pairs tunnel coherently while Coulomb blockade effects allow the control of the total charge, provide physical realizations of quantum bits (qubits), with logical states differing by one Cooper-pair charge on an island. The single- and two-bit operations required for quantum computation can be performed by ap

G. Els, G. S. Uhrig, P. Lemmens, H. Vonberg

Polarized inelastic light scattering experiments on Cu_(1-x)Zn_xGeO_3 (0<= x <= 0.045) single crystals show for x<>0 a new distinct mode at nearly half the energy of the singlet response below the spin-Peierls transition. The temperature, magnetic field, polarization, and doping dependencies of this mode are similar to those of the singlet bound state. The d

Sumio Ishihara, Sadamichi Maekawa

In order to determine types of the orbital ordering in manganites, we study theoretically the polarization dependence of the anomalous X-ray scattering which is caused by the anisotropy of the scattering factor. The general formulae of the scattering intensity in the experimental optical system is derived and the atomic scattering factor is calculated in the

E. Menendez-Proupin, J. L. Pena, C. Trallero-Giner

Resonant Raman scattering in semiconductor quantum dots with spherical shape is theoretically investigated. The Frohlich-like interaction between electronic states and optical vibrations has been considered. The Raman profiles are studied for the following intermediate electronic state models: (I) Uncorrelated electron-hole pairs in the strong size quantized

A. A. Slutskin, V. V. Slavin, H. A. Kovtun

It has been shown that effective lowering of dimension underlies ground-state space structure and properties of two-dimensional lattice systems with a long-range interparticle repulsion. On the basis of this fact a rigorous general procedure has been developed to describe the ground state of the systems.

Wolfram Just, Dirk Reckwerth, Johannes Möckel, Ekkehard Reibold

For controlling periodic orbits with delayed feedback methods the periodicity has to be known a priori. We propose a simple scheme, how to detect the period of orbits from properties of the control signal, at least if a periodic but nonvanishing signal is observed. We analytically derive a simple expression relating the delay, the control amplitude, and the

Bernard D. Seery, Eric P. Smith, John C. Mather

With the discovery of galaxies that existed when the universe was very young (approximately 5 percent of its current age), of planets not in our own solar system, and with the tantalizing evidence that the conditions for life may have existed within our solar system on planets or moons outside of the earth system, the past year has seen an explosion of inter

James D. Wells

A weakly interacting dark-matter particle may be difficult to discover at an accelerator because it either (1) is too massive, (2) has no standard-model gauge interactions, or (3) is almost degenerate with other states. In each of these cases, searches for annihilation products in the Galactic halo are useful probes of dark-matter properties. Using the examp

M. Birkinshaw

The Sunyaev-Zel&#39;dovich effect causes a change in the apparent brightness of the Cosmic Microwave Background Radiation towards a cluster of galaxies or any other reservoir of hot plasma. Measurements of the effect provide distinctly different information about cluster properties than X-ray imaging data, while combining X-ray and Sunyaev-Zel&#39;dovich eff

B. T. Gaensicke, D. W. Hoard, K. Beuermann, E. M. Sion

We present phase-resolved spectroscopy of AM Herculis obtained with the HST/GHRS when the system was in a high state. The ultraviolet light curve shows a quasi-sinusoidal modulation, which can be explained by a hot spot on the rotating white dwarf. The broad Lalpha absorption expected for photospheric radiation of a moderately hot white dwarf is largely fill

K. R. De Nisco, S. W. Bruenn, A. Mezzacappa

The effects of general relativity (GR) on the hydrodynamics and neutrino transport are examined during the critical shock reheating phase of core collapse supernovae. We find that core collapse computed with GR hydrodynamics results in a substantially more compact core structure out to the shock, the shock radius at stagnation being reduced by a factor of 2.

Thomas Kunzl, Harald Lesch, Axel Jessner, Alexis von Hoensbroech

We consider the widespread assumption that coherent pulsar radio emission is based on extended pair production leading to plasma densities highly exceeding the Goldreich-Julian density. We show as an example that the observed low frequency (160 MHz) emission of the Crab pulsar is incompatible to the model of extended pair production. Our results rule out sig

Hee-Won Lee, Jong-Hyeun Yun

Raman scattering by atomic hydrogen converts the UV continuum around Ly$β$ into optical continuum around H$α$, and the basic atomic physics has been discussed in several works on symbiotic stars. We propose that the same process may operate in active galactic nuclei (AGN) and calculate the linear polarization of the broad emission lines Raman-scattered by a

Angelica de Oliveira-Costa, Mark Devlin, Tom Herbig, Amber Miller

We present results from the QMAP balloon experiment, which maps the Cosmic Microwave Background (CMB) and probes its angular power spectrum on degree scales. In two separate flights, data were taken in six channels at two frequency bands between 26 to 46 GHz. We describe our method for mapmaking (removal of 1/f-noise and scan-synchronous offsets) and power s

Tom Herbig, Angelica de Oliveira-Costa, Mark Devlin, Amber Miller

We report the results from the second flight of QMAP, an experiment to map the cosmic microwave background near the North Celestial Pole. We present maps of the sky at 31 and 42 GHz as well as a measurement of the angular power spectrum covering the l-range 40-200. Anisotropy is detected at about 20 sigma and is in agreement with previous results at these an

Mark Devlin, Angelica de Oliveira-Costa, Tom Herbig, Amber Miller

We report on the first flight of the balloon-borne QMAP experiment. The experiment is designed to make a map of the cosmic microwave background anisotropy on angular scales from 0.7 to several degrees. Using the map we determine the angular power spectrum of the anisotropy in multipole bands from l~40 to l~140. The results are consistent with the Saskatoon (

Rafael A. Araya

This article has been withdrawn by the author as peer review found that a computational error invalidates the main conclusion of the paper. Nothing about cosmology can be concluded from the observed parameters for GB971214 alone. I have included a table with the correct luminosity distances for GB971214 at the correct redshift of z = 3.418

Robert S. Hill, Michael N. Fanelli, Denise A. Smith, Ralph C. Bohlin

The bright Magellanic irregular galaxy NGC 4449 was observed during the Astro-2 Space Shuttle mission by the Ultraviolet Imaging Telescope (UIT), which obtained images of a ~40 arcmin field centered on the galaxy in two broad far-ultraviolet (FUV) bands centered at 1520 A and 1620 A, with 3 arcsec - 5 arcsec spatial resolution. Together with H-alpha and H-be

Sebastian Jaimungal

We introduce new modified Abelian lattice models, with inhomogeneous local interactions, in which a sum over topological sectors are included in the defining partition function. The dual models, on lattices with arbitrary topology, are constructed and they are found to contain sums over topological sectors, with modified groups, as in the original model. The

Kurt Lechner

Starting from a manifestly Lorentz- and diffeomorphism-invariant classical action we perform a perturbative derivation of the gravitational anomalies for chiral bosons in 4n+2 dimensions. The manifest classical invariance is achieved using a newly developed method based on a scalar auxiliary field and two new bosonic local symmetries. The resulting anomalies

Ashok Das, A. J. da Silva

In an effort to further understand the structure of effective actions for fermions in an external gauge background at finite temperature, we study the example of 1+1 dimensional fermions interacting with an arbitrary Abelian gauge field. We evaluate the effective action exactly at finite temperature. This effective action is non-analytic as is expected at fi

Andrea Gregori, Costas Kounnas, P. Marios Petropoulos

We investigate the non-perturbative equivalence of some heterotic/type II dual pairs with N=2 supersymmetry. The perturbative heterotic scalar manifolds are respectively SU(1, 1)/U(1) x SO(2, 2+NV)/ SO(2) x SO(2+NV) and SO(4, 4+NH)/ SO(4) x SO(4+NH) for moduli in the vector multiplets and hypermultiplets. The models under consideration correspond, on the typ

Adrian Kent

It was pointed out recently [A. Kent, Phys. Rev. Lett. 78 (1997) 2874] that the consistent histories approach allows contrary inferences to be made from the same data. These inferences correspond to projections $P$ and $Q$, belonging to different consistent sets, with the properties that $PQ = QP = 0$ and $P \neq 1 -Q$. To many, this seems undesirable in a t

Yasuhiro Matsushita, Martin P. Gelfand, Chikara Ishii

Bond-operator mean field equations for the square-lattice, S=1/2 bilayer Heisenberg model are developed and solved numerically. In the vicinity of both the zero-field critical point and the field-induced transitions, comparisons are made with T=0 and finite-temperature strong coupling expansions. The mean-field theory suggests that the quantum critical regio

O. E. Barndorff-Nielsen, R. D. Gill

Braunstein and Caves (1994) proposed to use Helstrom&#39;s {\em quantum information} number to define, meaningfully, a metric on the set of all possible states of a given quantum system. They showed that the quantum information is nothing else than the maximal Fisher information in a measurement of the quantum system, maximized over all possible measurements

Deepak Dhar

The Abelian sandpile model is the simplest analytically tractable model of self-organized criticality. This paper presents a brief review of known results about the model. The abelian group structure allows an exact calculation of many of its properties. In particular, one can calculate all the critical exponents for the directed model in all dimensions. For

I. Pesando

We describe the type IIB supergravity background on AdS_{5} X S_{5} using the potentials of AdS_{5|4} X S_{5} and we use the supersolvable algebra associated to AdS_{5|4} to compute the k gauge fixed type IIB string action.

L. Burderi, A. R. King

We show that observations of X-ray pulsing from SAX J1808.4-3658 place a firm upper limit of 13.8 m^{1/3} km on the radius of the neutron star, where m is its mass in solar units. The limit is independent of distance or assumptions about the magnetospheric geometry, and could be significantly tightened by observations of the pulsations in the near future. We

H. Aratyn, E. Nissimov, S. Pacheva

We consider a broad class of consistently reduced Manin-Radul supersymmetric KP hierarchies (MR-SKP) which are supersymmetric analogs of the ordinary bosonic constrained KP models. Compatibility of these reductions with the MR fermionic isospectral flows is achieved via appropriate modification of the latter preserving their (anti-)commutation algebra. Unlik

H. Aratyn, E. Nissimov, S. Pacheva

We show that the system of the standard one-component KP hierarchy endowed with a special infinite set of abelian additional symmetries, generated by squared eigenfunction potentials, is equivalent to the two-component KP hierarchy.

V. Z. Nuri

This paper furthers the long historical examination of and debate on the foundations of quantum mechanics (QM) by presenting two local hidden variable (LHV) rules in the context of the EPRB experiment which violate Bell&#39;s inequality, but which are nevertheless local and deterministic under reasonable definitions of the terms, and coincide approximately w

Kalman Gyory, Min Ru

In this paper, we prove the finiteness of the number of integer solutions of the decomposable form inequalities. We also study the number of integer solutions of a sequence of decomposable form inequalities.

Alan Weinstein

An index formula is proposed for contact transformations between contact manifolds equipped with CR structures or with fillings by symplectic manifolds. The formula generalizes the Atiyah-Singer formula and gives a conjectured formula for the index of Fourier integral operators, as well as Epstein&#39;s relative index for CR structures.

Eric M. Opdam

In this paper we study the Hecke algebra associated with a complex reflection group W. We discuss some properties of the Galois group of the splitting field of this algebra, and study its action on the so-called fake degrees of W. The methods we use to study the Hecke algebra are based on the construction of representations of this algebra as monodromy of eq

Rainer Dick, Andrea Pollok-Narayanan, Harold Steinacker, Julius Wess

A $q$--deformed anharmonic oscillator is defined within the framework of $q$--deformed quantum mechanics. It is shown that the Rayleigh--Schrödinger perturbation series for the bounded spectrum converges to exact eigenstates and eigenvalues, for $q$ close to 1. The radius of convergence becomes zero in the undeformed limit.

Kei Miki

(1) Utilizing a Braid group action on a completion of U_q(\hat{sl_{n+1}}), an algebra homomorphism from the toroidal algebra U_q(sl_{n+1,tor}) (n\ge 2) with fixed parameter to a completion of U_q(\hat{gl_{n+1}}) is obtained. (2) The toroidal actions by Saito induces a level 0 U&#39;_q(\hat{sl_{n+1}}) action on level 1 integrable highest weight modules of U_q

Yi-Zhi Huang

This paper is the first in a series of papers developing a functional-analytic theory of vertex (operator) algebras and their representations. For an arbitrary Z-graded finitely-generated vertex algebra (V, Y, 1) satisfying the standard grading-restriction axioms, a locally convex topological completion H of V is constructed. By the geometric interpretation

Wolfgang M. Ruppert

We consider absolutely irreducible polynomials $f \in Z[x,y]$ with $°_x(f)=m$, $°_y(f)=n$ and height $H$. We show that for any prime $p$ with $p>c_{mn} H^{2mn+n-1}$ the reduction $f \bmod p$ is also absolutely irreducible. Furthermore if the Bouniakowsky conjecture is true we show that there are infinitely many absolutely irreducible polynomials $f \in Z[x,y

Wolfgang M. Ruppert

We give an elementary argument for the well known fact that the endomorphism algebra $End_Q(A)$ of a simple complex abelian surface $A$ can neither be an imaginary quadratic field nor a definite quaternion algebra. Another consequence of our argument is that a two-dimensional complex torus $T$ with $Q(\sqrt{d})\subseteq End_Q(A)$ where $Q(\sqrt{d})$ is real

Sergey Fomin, Andrei Zelevinsky

This paper focuses on the properties of Schubert cells as quasi-projective subvarieties of a generalized flag variety. More specifically, we investigate the problem of distinguishing between different Schubert cells using vanishing patterns of generalized Plucker coordinates.

J. Erlich, A. Naqvi

It has been shown that a procedure analogous to orbifolding in string theory, when applied to certain large N field theories, leaves correlators invariant perturbatively. We test nonperturbative agreement of some aspects of the orbifolded and non-orbifolded theories. More specifically, we find that the period matrices of parent and orbifolded Seiberg-Witten

Peter Bantay

The connection between the theory of permutation orbifolds, covering surfaces and uniformization is investigated, and the higher genus partition functions of an arbitrary permutation orbifold are expressed in terms of those of the original theory.

Seiji Terashima, Sung-Kil Yang

We obtain the Seiberg-Witten geometry for four-dimensional N=2 gauge theory with gauge group SO(2N_c) (N_c \leq 5) with massive spinor and vector hypermultiplets by considering the gauge symmetry breaking in the N=2 $E_6$ theory with massive fundamental hypermultiplets. In a similar way the Seiberg-Witten geometry is determined for N=2 SU(N_c) (N_c \leq 6) g

Marek Pawlowski

The Weyl-Weinberg-Salam model is presented. It is based on the local conformal gauge symmetry. The model identifies the Higgs scalar field in SM with the Penrose-Chernikov-Tagirov scalar field of the conformal theory of gravity. Higgs mechanism for generation of particle masses is replaced by the originated in Weyl&#39;s ideas conformal gauge scale fixing. S

Zurab Kakushadze

We briefly review some recent developments in large N gauge theories which utilize the power of string perturbation techniques.

R. N. Mohapatra

A sterile neutrino in addition to the three known neutrinos seems unavoidable if one wants a simultaneous understanding of the results of the LSND experiment indicating $ν_μ-ν_e$ oscillation together with other evidences for neutrino oscillations such as those from solar and atmospheric neutrino deficits. A major theoretical challenge then is to understand w

Spencer R. Klein

The suppression of photon bremsstrahlung due to a variety of in-medium effects is discussed. Different electrodynamic suppression effects are discussed, and compared with the related color analogs. Higher order effects are considered, and found to be important. Data from SLAC E-146 is discussed, and compared with theory. The effect of finite thickness target

Bogdan Mihaila, John F. Dawson, Fred Cooper, Mary Brewster

We investigate the quantum roll for a particle in a $d$-dimensional ``Mexican hat&#39;&#39; potential in quantum mechanics, comparing numerical simulations in $d$-dimensions with the results of a large-$d$ expansion, up to order $1/d$, of the coupled closed time path (CTP) Green&#39;s function equations, as well as to a post-Gaussian variational approximatio

P. V. Landshoff, O. Nachtmann

On March 19-21, 1998, a workshop devoted to questions of the pomeron and the odderon in high energy scattering was held in Heidelberg. This note gives a personal account of some of the issues discussed at this workshop. Of course, misconceptions and misunderstandings are to be blamed on us, not on the other participants of the workshop. A puzzle of odderon p

Anjan S. Joshipura, Sudhir K. Vempati

Supersymmetric standard model with softly broken lepton symmetry provides a suitable framework to accommodate the solar and atmospheric neutrino anomalies. This model contains a natural explanation for large mixing and hierarchal masses without fine tuning of the parameters. Neutrino spectrum is particularly constrained in the minimal messenger model (MMM) o

A. Harindranath, Rajen Kundu, Asmita Mukherjee, James P. Vary

To resolve various outstanding issues associated with the twist four longitudinal structure function ${F_L^{τ=4}(x)}$ we perform an analysis based on the BJL expansion for the forward virtual photon-hadron Compton scattering amplitude and equal (light-front) time current algebra. Using the Fock space expansion for states and operators, we evaluate the twist

D. Drechsel, G. Krein

The long-standing discrepancy between the Gerasimov-Drell-Hearn sum rule and the analysis of pion photoproduction multipoles is greatly diminished by use of s-wave multipoles that are in accord with the predictions of chiral perturbation theory and describe the experimental data in the threshold region. The remaining difference may be due to contributions of

Patricia Ball, V. M. Braun

We give a summary of existing results on higher twist distribution amplitudes of vector mesons in QCD. Special attention is payed to meson mass corrections which turn out to be large. A ``shopping list&#39;&#39; is presented of most important nonperturbative parameters which enter distribution amplitudes.

M. Strohmeier-Presicek, T. Gutsche, A. Faessler, R. Vinh Mau

We investigate the two-body decay modes $ρρ, ππ^{\ast}(1300)$ and $σσ$ of the $f_0(1500)$, all leading to the $4π$ decay channel, in a three-state mixing scheme, where the $f_0(1500)$ is a mixture of the lowest-lying scalar glueball with the nearby isoscalar states of the $0^{++} Q\bar{Q}$ nonet. In the leading order of this scheme, the decay mechanism of th

S. Y. Choi, J. S. Shim, H. S. Song, W. Y. Song

One CP--odd rephase-invariant phase appears in the chargino mass matrix in the minimal Supersymmetric Standard Model. We investigate in detail the phenomenological impacts of the CP-odd complex phase in the production of light charginos in $e^+e^-$ annihilation. The values of the chargino masses and the mixing angles, determining the size of the wino and hig

Arkady Vainshtein

The &#39;t Hooft model (two-dimensional QCD in the limit of large number of colors) is used as a testground for calculations of nonleptonic and semileptonic inclusive widths of heavy flavors based on the operator product expansion (OPE). The OPE-based predictions up to terms ${\cal O}(1/m_Q^4)$, inclusively, are confronted with the &#34;phenomenological&#34;

Alexander Donnachie, Philip R. Page

We investigate theoretical interpretations of the 1.4 GeV J^PC exotic resonance reported by the E852 collaboration. It is argued that interpretation in terms of a hybrid meson is untenable. A K-matrix analysis shows that the 1.4 GeV enhancement in the E852 eta pi data can be understood as an interference of a non-resonant Deck-type background and a resonance

H. I. M. Lichtenegger, F. Gronwald, B. Mashhoon

Based on the recent finding that the difference in proper time of two clocks in prograde and retrograde equatorial orbits about the Earth is of the order 10^{-7}s per revolution, the possibility of detecting the terrestrial gravitomagnetic field by means of clocks carried by satellites is discussed. A mission taking advantage of this influence of the rotatin

S. B. Edgar, J. A. Vickers

A new method is presented for obtaining the general conformally flat radiation metric by using the differential operators of Machado Ramos and Vickers (a generalisation of the GHP operators) which are invariant under null rotations and spin and boosts. The solution is found by constructing involutive tables of these derivatives applied to the quantities whic

Norimasa Sugiura

We study the distance-redshift relation in a universe filled with point particles, and discuss what the universe looks like when we make the number of particles N very large, while fixing the averaged mass density. Using the Raychaudhuri equation and a simple analysis of the probability of strong lensing effects, we show that the statistical nature of the am

Norimasa Sugiura, Ken-ichi Nakao, Tomohiro Harada

The relation between angular diameter distance and redshift in a spherically symmetric dust-shell universe is studied. This model has large inhomogeneities of matter distribution on small scales. We have discovered that the relation agrees with that of an appropriate Friedmann-Lemaitre(FL) model if we set a ``homogeneous&#39;&#39; expansion law and a ``homog

R. W. Nunes, I. I. Mazin, D. J. Singh

We investigate the thermoelectric properties of some semiconducting Chevrel phases. Band structure calculations are used to compute thermopowers and to estimate of the effects of alloying and disorder on carrier mobility. Alloying on the Mo site with transition metals like Re, Ru or Tc to reach a semiconducting composition causes large changes in the electro

G. Cao, V. Dobrosavljevic, S. McCall, J. E. Crow

The temperature dependence of the electrical resistivity of two chemically substituted Ca-ruthenates is examined with the Efros-Shklovskii mechanism invoking Coulomb interactions between carriers. Additional mechanisms causing an energy dependence to the density of states at the Fermi surface may explain the unusually wide temperature and conductivity range

P. L. Krapivsky, J. F. F. Mendes, S. Redner

We investigate the kinetics of submonolayer epitaxial growth which is driven by a fixed flux of monomers onto a substrate. Adatoms diffuse on the surface, leading to irreversible aggregation of islands. We also account for the effective diffusion of islands, which originates from hopping processes of their constituent adatoms, on the kinetics. When the diffu

I. L. Aleiner, B. L. Altshuler, M. E. Gershenson

This paper is intended to demonstrate that there is no need to revise the existing theory of the transport properties of disordered conductors in the so-called weak localization regime. In particular, we demonstrate explicitly that recent attempts to justify theoretically that the dephasing rate (extracted from the magnetoresistance) remains finite at zero t

Alexander J. Wagner

The lattice Boltzmann equation can be viewed as a discretization of the continuous Boltzmann equation. Because of this connection it has long been speculated that lattice Boltzmann algorithms might obey an H-theorem. In this letter we prove that usual nine-velocity models do not obey an H-theorem but models that do obey an H-theorem can be constructed. We co

A. Calogeracos, G. E. Volovik

The Lancaster experiments with a cylindrical wire moving in superfluid 3He-B are discussed, where the measured critical velocity of pair creation is much below the Landau critical velocity. The phenomenon is shown to be analogous to the instability of the electron-positron vacuum in an adiabatically alternating strong electric potential of both signs, where

A. V. Boris, N. N. Kovaleva, A. V. Bazhenov, P. J. M. van Bentum

The infrared reflectivity of a $\rm La_{0.67}Ca_{0.33}MnO_3$ single crystal is studied over a broad range of temperatures (78-340 K), magnetic fields (0-16 T), and wavenumbers (20-9000 cm$^{-1}$). The optical conductivity gradually changes from a Drude-like behavior to a broad peak feature near 5000 cm$^{-1}$ in the ferromagnetic state below the Curie temper

Raffaella Burioni, Davide Cassi, Alessandro Vezzani

In this paper we prove the existence of phase transitions at finite temperature for O(n) classical ferromagnetic spin models on infrared finite graphs. Infrared finite graphs are infinite graphs with $\lim {m\to 0^+} {\bar Tr (L+m)^{-1} < \infty$, where $L$ is the Laplacian operator of the graph. The ferromagnetic couplings are only requested to be bounded b