July 1997 arXiv papers — page 5

T. K. Gaisser

This is a review of high energy neutrino astronomy that might be done with a kilometer-scale detector. The emphasis is on diffuse neutrinos of extragalactic origin and their relation to possible sources of the highest energy cosmic rays, such as active galaxies, cosmological gamma-ray burst sources and topological defects.

T. J. Galama, P. J. Groot, R. G. Strom, J. van Paradijs

We report on Westerbork 840 MHz, 1.4 and 5 GHz radio observations of the improved IPN-WFC error box of the gamma-ray burst GRB 970111, between 26.4 hours and 120 days after the event onset. In the ~ 13 sq arcmin area defined by the IPN (BATSE and Ulysses) annulus and the published refined BeppoSAX Wide Field Camera error box we detected no steady sources bri

Mark J. Neeser, Klaus Meisenheimer, Hans Hippelein

We present the results of an extensive Fabry-Perot investigation of the extended line-emission gas surrounding powerful radio galaxies. High spatial (1.4 arcsec) and kinematical (400 km/s) resolution observations of the [OII]3727 emission-line of the powerful, double radio source 3C34 (z=0.689) are given. We present evidence that anisotropic radiation emanat

K. Subramanian

Large-scale magnetic fields in galaxies are thought to be generated by a turbulent dynamo. However the same turbulence also leads to a small-scale dynamo which generates magnetic noise at a more rapid rate. The efficiency of the large-scale dynamo depends on how this noise saturates. We examine this issue taking into account ambipolar drift, which obtains in

F. Legrand, D. Kunth, J. -R. Roy, J. M. Mas-Hesse

Wolf-Rayet stars (WR) have been detected in the NW region of the metal-poor starburst galaxy IZw 18. The integrated luminosity and FWHM of the bumps at 4650 A and 5808 A are consistent with the presence of a few individual stars of WC4 or WC5 type. Evolutionary synthesis models predict few WRs in this galaxy, but only of WN type. The presence of WC stars at

M. Baldo, I. Bombaci, G. F. Burgio

We calculate static properties of non-rotating neutron stars (NS's) using a microscopic equation of state (EOS) for asymmetric nuclear matter, derived from the Brueckner-Bethe-Goldstone many-body theory with explicit three-body forces. We use the Argonne AV14 and the Paris two-body nuclear force, implemented by the Urbana model for the three-body force.

F. Wyrowski, P. Schilke, P. Hofner, C. M. Walmsley

We have carried out VLA D-array observations of the C91alpha carbon recombination line as well as Effelsberg 100-m observations of the C65alpha line in a 5 arcmin square region centered between the Bar and the Trapezium stars in the Orion Nebula with spatial resolutions of 10 arcsec and 40 arcsec, respectively. The results show the ionized carbon in the PDR

J. E. Hibbard, W. D. Vacca

We use rest frame ultraviolet (UV), B, and V band images of five nearby (z<0.02) interacting and/or starbursting galaxies to simulate deep HST observations of peculiar galaxies at medium to high redshifts. In particular, we simulate Hubble Deep Field (HDF) observations in the F606W and F814W filters of starburst galaxies in the redshift range z~0.5---2.5 by

J. Robert Buchler

We review some of the recent advances in nonlinear pulsation theory, but also insist on some of the major extant shortcomings.

Jane C. Charlton, Christopher W. Churchill

A consensus is developing on the nature of various populations of absorbers at different redshift regimes and in particular on their relationships to galaxies at those epochs. As one example we discuss the population of z < 1 MgII absorbers. Kinematic models are presented that show this population to be consistent with some combination of halo and disk kinem

Sean Keel, James McKernan

The main result is that a quasi-projective surface has negative log Kodaira dimension (i.e. no log pluricanonical sections) iff it is dominated by images of the affine line. This follows from our main intermediate result, that the smooth locus of a log Fano surface is rationally connected. We also give a classification of all but a bounded family of rank one

Markus Laukamp, George Balster Martins, Claudio J. Gazza, Andre L. Malvezzi

Spin models that have been proposed to describe dimerized chains, ladders, two dimensional antiferromagnets, and other compounds are here studied when some spins are replaced by spinless vacancies, such as it occurs by $Zn$ doping. A small percentage of vacancies rapidly destroys the spin gap, and their presence induces enhanced antiferromagnetic correlation

K. S. Babu, Q. Y. Liu, A. Yu. Smirnov

We consider the Grand Unification (GU) scenario for neutrino masses which is based on the see-saw mechanism with the mass of the heaviest right handed (RH) neutrino at the GU-scale: $M_3 \sim Λ_{GU}$, and on the quark-lepton symmetry for fermions from the third generation. The scenario predicts for the light neutrinos: $m_3 \sim (2 - 4) \cdot 10^{-3}$ eV and

S. C. Woon

We are used to thinking of an operator acting once, twice, and so on. However, an operator acting integer times can be consistently analytic continued to an operator acting complex times. Applications: (s,r) diagrams and an extension of Fractional Calculus where commutativity of fractional derivatives is preserved, generating integrals and non-standard deriv

Shinya Kanemura, Hide-Aki Tohyama

The non-decoupling effects of heavy Higgs bosons on the process $e^+e^- \to W^+_LW^-_L$ are discussed in the two Higgs-doublet model. The one-loop corrections to the cross section are calculated by using the equivalence theorem and the explicit expressions of its deviation from the standard model are derived. The leading mass contributions to the deviation i

Beatriz Gato-Rivera

There are two different spectral flows on the N=2 superconformal algebras (four in the case of the Topological algebra). The usual spectral flow, first considered by Schwimmer and Seiberg, is an even transformation, whereas the spectral flow previously considered by the author and Rosado is an odd transformation. We show that the even spectral flow is genera

R. Martinez, J. -Alexis Rodriguez L.

We derive a bound on the magnetic dipole moment of the top quark in the context of the effective Lagrangian approach by using the values of the ratio $R_b = Γ_b/Γ_h$, $R_l = Γ_h/Γ_l$ and $Γ_Z$. We found that the oblique corrections are more sensible than the vertex ones for this moment.

I. Antoniadis, M. Quiros

We present an additional test of the recent proposal for describing supersymmetry breaking due to gaugino condensation in the strong coupling regime, by a Scherk-Schwarz mechanism on the eleventh dimension of M-theory. An analysis of supersymmetric transformations in the infinite-radius limit reveals the presence of a discontinuity in the spinorial parameter

E. Cremmer, H. Lu, C. N. Pope, K. S. Stelle

We show that there exist nonlinearly realised duality symmetries that are independent of the standard supergravity global symmetries, and which provide active spectrum-generating symmetries for the fundamental BPS solitons. The additional ingredient, in any spacetime dimension, is a single scaling transformation that allows one to map between BPS solitons wi

Yuji Sugawara, Katsuyuki Sugiyama

We give a confirmation of U-duality of type II superstring by discussing mass spectrum of the BPS states. We first evaluate the mass spectrum of BPS solitons with one kind of R-R charges. Our analysis is based on the 1-loop effective action of D-brane, which is known as ``Dirac-Born-Infeld (DBI) action&#39;&#39;, and the fact that BPS states correspond to th

Georg G. Raffelt

The observed properties of stars and especially the neutrino signal of the supernova 1987A provide an upper limit to the axion mass, while the age and expansion rate of the universe provide a lower limit. There remains a &#34;window of opportunity&#34; 10^{-5} eV < m_a < 10^{-2} eV, with large uncertainties on either side, where axions could still exist and

E. M. C. de Abreu, R. Banerjee, C. Wotzasek

We show in a precise way, either in the fermionic or its bosonized version, that Bose symmetry provides a systematic way to carry out the chiral decomposition of the two dimensional fermionic determinant. Interpreted properly, we show that there is no obstruction of this decomposition to gauge invariance, as is usually claimed. Finally, a new way of interpre

G. Bimonte, R. Musto, A. Stern, P. Vitale

Using the tools of q--differential calculus and quantum Lie algebras associated to quantum groups, we find a one--parameter family of q-gauge theories associated to the quantum group $ISO_q(3,1)$. Although the gauge fields, that is the spin--connection and the vierbeins are non--commuting objects depending on a deformation parameter, $q$, it is possible to c

J. Donin

For $\g=sl(n)$ we construct a two parametric $U_h(\g)$-invariant family of algebras, $(S\g)_{t,h}$, which defines a quantization of the function algebra $S\g$ on the coadjoint representation and in the parameter $t$ gives a quantization of the Lie bracket. The family induces a two parametric deformation of the function algebra of any maximal orbit which is a

T. Scheidsteger, H. Urbschat, R. B. Griffiths, H. J. Schellnhuber

A procedure is described for efficiently finding the ground state energy and configuration for a Frenkel-Kontorova model in a periodic potential, consisting of N parabolic segments of identical curvature in each period, through a numerical solution of the convex minimization problem described in the preceding paper. The key elements are the use of subdiffere

F. Lizzi, R. J. Szabo

We examine the structure of spacetime symmetries of toroidally compactified string theory within the framework of noncommutative geometry. Following a proposal of Frohlich and Gawedzki, we describe the noncommutative string spacetime using a detailed algebraic construction of the vertex operator algebra. We show that the spacetime duality and discrete worlds

Michael W. Deem, Jeong-Man Park

We derive the long-time behavior of the ${A} + {B} \to \emptyset$ reaction in two dimensions, finding a universal exponent and prefactor in the absence of disorder. Sufficiently singular disorder leads to a (sub)diffusion-limited reaction and a continuously variable decay exponent. Pattern matching between the reactant segregation and the disorder is not str

K. Ezawa, Y. Matsuo, K. Murakami

We study open supermembranes in 11 dimensional rigid superspace with 6 dimensional topological defects (M-theory five-branes). After rederiving in the Green-Schwarz formalism the boundary conditions for open superstrings in the type IIA theory, we determine the boundary conditions for open supermembranes by imposing kappa symmetry and invariance under a frac

Hal Tasaki

Derivation of the canonical (or Boltzmann) distribution based only on quantum dynamics is discussed. Consider a closed system which consists of mutually interacting subsystem and heat bath, and assume that the whole system is initially in a pure state (which can be far from equilibrium) with small energy fluctuation. Under the "hypothesis of equal weights fo

T. Grava

The Korteweg de Vries (KdV) equation with small dispersion is a model for the formation and propagation of dispersive shock waves in one dimension. Dispersive shock waves in KdV are characterized by the appearance of zones of rapid modulated oscillations in the solution of the Cauchy problem with smooth initial data. The modulation in time and space of the a

L. E. Saltini, A. Zadra

We derive the classical algebra of the non-local conserved charges in the O(N) WZNW model and analyze its dependence on the coupling constant of the Wess-Zumino term. As in the non-linear sigma model, we find cubic deformations of the O(N) affine algebra. The surprising result is that the cubic algebra of the WZNW non-local charges does not obey the Jacobi i

Q. P. Liu

The constrained Modified KP hierarchy is considered from the viewpoint of modification. It is shown that its second Poisson bracket, which has a rather complicated form, is associated to a vastly simpler bracket via Miura-type map. The similar results are established for a natural reduction of MKP.

M. Blasone, Y. N. Srivastava, G. Vitiello, A. Widom

The quantum theory of Brownian motion is discussed in the Schwinger version wherein the notion of a coordinate moving forward in time $x(t)$ is replaced by two coordinates, $x_+(t)$ moving forward in time and $x_-(t)$ moving backward in time. The role of the doubling of the degrees of freedom is illustrated for the case of electron beam two slit diffraction

Asher Peres

Entanglement is essential for quantum computation. However, disentanglement is also necessary. It can be achieved without the need of classical operations (measurements). Two examples are analyzed: the discrete Fourier transform and error correcting codes.

Steve Awodey, Carsten Butz

Using recent results in topos theory, two systems of higher-order logic are shown to be complete with respect to sheaf models over topological spaces---so-called ``topological semantics&#39;&#39;. The first is classical higher-order logic, with relational quantification of finitely high type; the second system is a predicative fragment thereof with quantific

Matthias Klein, Jan Louis

In this paper we discuss the singularities in the Yukawa and gauge couplings of N=1 compactifications of the SO(32) heterotic string in four space-time dimensions. Such singularities can arise from the strong coupling dynamics of a confined non-perturbative gauge group.

J. C. Le Guillou, E. F. Moreno, C. Nunez, F. A. Schaposnik

We show that, with the help of a general BRST symmetry, different theories in 3 dimensions can be connected through a fundamental topological field theory related to the classical limit of the Chern-Simons model.

F. Fucito, A. Tanzini, L. C. Q. Vilar, O. S. Ventura

Lectures given at the First School on Field Theory and Gravitation, Vitória, Esp\&#39;ırito Santo, Brazil, 15-19 April, 1997.

L. Andrianopoli, R. D&#39;Auria, S. Ferrara

In these lectures we give a geometrical formulation of N-extended supergravities which generalizes N=2 special geometry of N=2 theories. In all these theories duality symmetries are related to the notion of &#34;flat symplectic bundles&#34; and central charges may be defined as &#34;sections&#34; over these bundles. Attractor points giving rise to &#34;fixed

M. Carena, Debajyoti Choudhury, Sreerup Raychaudhuri, C. E. M. Wagner

A light stop, with an R-parity-violating coupling $λ&#39;_{131}$, has been suggested as an explanation of the excess in high-$Q^2$ neutral current events observed at the HERA collider. We show that in this scheme a corresponding excess in charged current events --- such as that reported by the H1 Collaboration --- can appear naturally, without calling for th

Gia Dvali, Lawrence M. Krauss, Hong Liu

The prototype hybrid SUSY SU(5) inflation models, while well motivated from particle physics, and while allowing an acceptable inflationary phase with little or no fine tuning, are shown to have two fundamental phenomenological problems. (1) They inevitably result in the wrong vacuum after inflation is over; and (2) they do not solve the monopole problem. In

J. B. Bronzan

In electroweak baryogenesis, a domain wall between the spontaneously broken and unbroken phases acts as a separator of baryon (or lepton) number, generating a baryon asymmetry in the universe. If the wall is thin relative to plasma mean free paths, one computes baryon current into the broken phase by determining the quantum mechanical transmission of plasma

E. H. Simmons

Experiment shows that the top quark is far heavier than the other elementary fermions. This finding has stimulated research on theories of electroweak and flavor symmetry breaking that include physics beyond the standard model. Efforts to accommodate a heavy top quark within existing frameworks have revealed constraints on model-building. Other investigation

M. Cvetic, P. Langacker

We review the status of heavy neutral gauge bosons, Z&#39;, with emphasis on constraints that arise in supersymmetric models, especially those motivated from superstring compactifications. We first summarize the current phenomenological constraints and the prospects for Z&#39; detection and diagnostics at the LHC and NLC. After elaborating on the status and

Christopher Kolda

Recent progress in the gauge-mediated supersymmetry breaking is reviewed, with emphasis on the theoretical problems which gauge-mediated models so successfully solve, as well as those problems which are endemic to the models themselves and still beguile theorists today.

Michael Krämer

I discuss the impact of color-octet contributions to inclusive $J/ψ$ photoproduction at HERA. Emphasis is put on resolved photon processes and on $J/ψ$ polarization, which will be experimentally accessible at HERA in the near future. Both analyses provide a powerful test of the NRQCD factorization approach to charmonium production.

Carl R. Schmidt

We present a calculation of the two-loop helicity amplitudes for the processes H-->ggg and H-->gqqbar in the large-M_t limit. In this limit the calculation can be performed in terms of one-loop diagrams containing an effective Hgg operator. These amplitudes are required for the next-to-leading order (NLO) corrections to the Higgs transverse momentum distribu

D. Schildknecht, H. Spiesberger

The HERA data on inelastic lepton proton scattering for values of the Bjorken scaling variable x < 0.05 are confronted with predictions based on Generalized Vector Dominance. Good agreement between theory and experiment is found over the full kinematic range of the squared four-momentum-transfer, Q^2, from Q^2 = 0 (photoproduction) to Q^2 < 350 GeV^2.

M. Kuroda

Algorithm of constructing Feynman amplitudes in the framework of minimal supersymmetic extension of the standard model is presented, which can be easily implemented in GRACE, the program of automatic generation of Feynman amplitudes. The equivalence of our method with the prescription given by Denner et al. is proved.

P. Bauleo, A. Etchegoyen, J. O. Fernandez Niello, A. M. J. Ferrero

Extensive airshower detection is an important issue in current astrophysics endeavours. Surface arrays detectors are a common practice since they are easy to handle and have a 100% duty cycle. In this work we present an experimental study of the parameters relevant to the design of a water Cerenkov detector for high energy airshowers. This detector is concei

Eckhard Meinrenken, Chris Woodward

We construct an oriented cobordism between moduli spaces of flat connections on the three holed sphere and disjoint unions of toric varieties, together with a closed two-form which restricts to the symplectic forms on the ends. As applications, we obtain formulas for mixed Pontrjagin numbers and Witten&#39;s formulas for symplectic volumes.

Eckhard Meinrenken, Chris Woodward

We discuss Witten&#39;s formulas for the symplectic volumes of moduli spaces of flat connections on 2-manifolds from the viewpoint of Hamiltonian cobordism as introduced by Ginzburg-Guillemin-Karshon.

L. Andersson, M. Dahl

Rigidity results for asymptotically locally hyperbolic manifolds with lower bounds on scalar curvature are proved using spinor methods related to the Witten proof of the positive mass theorem. The argument is based on a study of the Dirac operator defined with respect to the Killing connection. The existence of asymptotic Killing spinors is related to the sp

O. Schmitt, H. Endres, W. Hanke, R. Kleiner

A quantitative analysis of a microscopic model for the intrinsic Josephson effect in high-temperature superconductors based on interlayer tunneling is presented. The pairing correlations in the CuO_2-planes are modelled by a 2-D Hubbard-model with attractive interaction, a model which accounts well for some of the observed features such as the short planar c

Th. M. Nieuwenhuizen

In order to find out whether there exists a thermodynamic description of the glass phase, the Ehrenfest relations along the glass transition line are reconsidered. It is explained that the one involving the compressibility is always satisfied, and that the one involving the specific heat is principally incorrect. Thermodynamical relations are presented for n

Pierpaolo Bruscolini

A phenomenological model hamiltonian to describe the folding of a protein with any given sequence is proposed. The protein is thought of as a collection of pieces of helices; as a consequence its configuration space increases with the number of secondary structure elements rather than with the number of residues. The hamiltonian presents both local (i.e. sin

A. Gonzalez, B. Partoens, F. M. Peeters

Analytic approximations to the ground-state energy of closed-shell quantum dots (number of electrons from 2 to 210) are presented in the form of two-point Pade approximants. These Pade approximants are constructed from the small- and large-density limits of the energy. We estimated that the maximum error, reached for intermediate densities, is less than 3%.

A. Rodriguez, F. Dominguez-Adame

We consider the dynamics of Frenkel excitons on quasiperiodic lattices, focusing our attention on the Fibonacci case as a typical example. We evaluate the absorption spectrum by solving numerically the equation of motion of the Frenkel-exciton problem on the lattice. Besides the main absorption line, satellite lines appear in the high-energy side of the spec

Hal Tasaki

This is a note associated with my paper &#34;From Quantum Dynamics to the Canonical Distribution: A Rigorous Derivation in Special Models&#34; (cond-mat/9707253). Here I describe all the technical details which are not discussed in the main paper.

Yuri I. Izotov, Craig B. Foltz, Richard F. Green, Natalia G. Guseva

We report the discovery of broad Wolf-Rayet emission lines in the Multiple Mirror Telescope (MMT) spectrum of the NW component of I Zw 18, the lowest-metallicity blue compact dwarf (BCD) galaxy known. Two broad Wolf-Rayet (W-R) bumps at the wavelengths $λ$4650 and $λ$5800 are detected indicating the presence of WN and WC stars. The total numbers of WN and WC

Charlotte Cheung, Joao Magueijo

We introduce a non-Gaussian model of structure formation, and show how it produces surprising sampling effects on the estimation of the CMB power spectrum. Estimates of the average power spectrum based on small sky patches produce qualitatively different results from patch to patch, and vary also with the patch size. For instance a system of secondary Dopple

J. Cepa, F. de Pablos

A new method of evaluating relative (arm with respect to the interarm disk) star formation rates and relative star formation efficiencies, together with spiral arm-amplitudes, as a function of the galactocentric radius, using broad-band photometry is derived. The classical method for obtaining star formation rates from H_alpha photometry is discussed, and a

D. A. White, C. Jones, W. Forman

We present an X-ray image deprojection analysis of Einstein Observatory imaging data on 207, clusters of galaxies. The resulting radial profiles for luminosity, temperature, and electron density variations are determined from the cluster surface-brightness profiles according to gravitational potential constraints from average Tx and Vopt observations. This e

D. Boyanovsky, D. Cormier, H. J. de Vega, R. Holman

The physics of the inflationary universe requires the study of the out of equilibrium evolution of quantum fields in curved spacetime. We present the evolution for both the geometry and the matter (described by the quantum inflaton field) by means of the non-perturbative large N limit combined with semi-classical gravitational dynamics including the back-rea

P. A. Denissenkov, G. S. Da Costa, J. E. Norris, A. Weiss

Star-to-star abundance variations of C, N, O, Na and Al in globular-cluster red giants have been recently supplemented by the finding that [Mg/Fe] is depleted in stars with extremely large [Al/Fe] (Shetrone 1996a). This and other new spectroscopic results allow us to test current models of stellar evolution and nucleosynthesis, as well as those of the format

Andy Taylor, Alan Heavens, Bill Ballinger, Max Tegmark

We discuss the problems of applying Maximum Likelihood methods to the CMB and how one can make it both efficient and optimal. The solution is a generalised eigenvalue problem that allows virtually no loss of information about the parameter being estimated, but can allow a substantial compression of the data set. We discuss the more difficult question of simu

Hideo Matsuhara, Masahiro Tanaka, Yoshinori Yonekura, Yasuo Fukui

We report the results of a rocket-borne observation of [C II] 158\micron line and far-infrared continuum emission at 152.5\micron toward the high latitude molecular clouds in Ursa Major. We also present the results of a follow-up observation of the millimeter ^{12}CO J=1-0 line over a selected region observed by the rocket-borne experiment. We have discovere

Ennio Poretti, Federica Musazzi

The photometric properties of the variable stars located in the lower part of the classical instability strip are discussed. The importance of the determination of some light curve parameters and their connection with the stellar models are stressed, with a particular emphasis on large amplitude Delta Sct (DSCT) stars.

Andrea Ferrara

I review the capabilities of H$α$ observations to constrain some aspects of the current models of the interstellar medium. In particular, it is shown that turbulence is a necessary ingredient of any viable model, since most of the energy produced by supernova explosions and ionizing radiation is stored in kinetic form in the ISM. Various forms of turbulent e

Adam G. Riess, Marc Davis, Jonathan Baker, Robert P. Kirshner

We compare the peculiar velocities of nearby SNe Ia with those predicted by the gravity fields of full sky galaxy catalogs. The method provides a powerful test of the gravitational instability paradigm and strong constraints on the density parameter beta = Omega^0.6/b. For 24 SNe Ia within 10,000 km/s we find the observed SNe Ia peculiar velocities are well

A. G. Riess, A. V. Filippenko, D. C. Leonard, B. P. Schmidt

We have developed a quantitative, empirical method for estimating the age of Type Ia supernovae (SNe Ia) from a single spectral epoch. The technique examines the goodness of fit of spectral features as a function of the temporal evolution of a large database of SNe Ia spectral features. When a SN Ia spectrum with good signal-to-noise ratio over the rest fram

Arnaud Beauville

A contact structure on a complex manifold M is a corank 1 subbundle F of T(M) such that the bilinear form on F with values in the quotient line bundle L=T(M)/F deduced from the Lie bracket of vector fields is everywhere non-degenerate. In this paper we consider the case where M is a Fano manifold; this implies that L is ample. If g is a simple Lie algebra, t

Fabio Bernardini, Vincenzo Fiorentini, David Vanderbilt

We present a novel method for the calculation of the static and electronic dielectric tensor of polar insulating crystals based on concepts from the modern theory of dielectric polarization. As an application, we present the first ab initio calculation of the dielectric constants in the wurtzite III-V nitrides AlN, GaN, and InN.

H. C. Rosu, M. A. Reyes

We determine the class of damped modes \tilde{y} which are related to the common free damping modes y by supersymmetry. They are obtained by employing the factorization of Newton&#39;s differential equation of motion for the free damped oscillator by means of the general solution of the corresponding Riccati equation together with Witten&#39;s method of cons

C. Klimcik

A duality invariant action for (1,1) supersymmetric extension of Poisson-Lie dualizable $σ$-models is constructed.

Amihay Hanany, Kentaro Hori

Type IIA brane configurations are used to construct N=2 supersymmetric gauge theories in two dimensions. Using localization of chiral multiplets in ten-dimensional spacetime, supersymmetric non-linear sigma models with target space such as $\CP^{n-1}$ and the Grassmann manifolds are studied in detail. The quantum properties of these models are realized in $M

Ralph Blumenhagen

The moduli spaces of two (0,2) compactifications of the heterotic string can share the same Landau-Ginzburg model even though at large radius they look completely different. It was argued that such a pair of (0,2) models might be connected via a perturbative transition at the Landau-Ginzburg point. Situations of this kind are studied for some explicit models

Nickolay Y. Gnedin

The paper is withdrawn.

Luca Bombelli, Fernando C. Lombardo, Mario Castagnino

Chaos in Robertson-Walker cosmological models where gravity is coupled to one or more scalar fields has been studied by a few authors, mostly using numerical simulations. In this paper we begin a systematic study of the analytical aspect. We consider one conformally coupled scalar field and, using the fact that the model is integrable when the field is massl

Nick Evans

We review progress in studying the solutions of SQCD in the presence of explicit, soft SUSY breaking terms. Massive N=1 SQCD in the presence of a small gaugino mass leads to a controlled solution which has interesting phase structure with changing theta angle reminiscent of the QCD chiral Lagrangian. Current attempts to test the solutions of pure glue SQCD o

Dirk Kreimer

We show that the process of renormalization encapsules a Hopf algebra structure in a natural manner. This sheds light on the recently proposed connection between knots and renormalization theory.

G. Oron, H. J. Herrmann

We present calculations of forces for two dimensional static sandpile models. Using a symbolic calculation software we obtain exact results for several different orientations of the lattice and for different types of supporting surfaces. The model is simple, supposing spherical, identical, rigid particles on a regular triangular lattice, without friction and

Holger F. Hofmann, Guenter Mahler, Ortwin Hess

We investigate the possibilities of preserving and manipulating the coherence of atomic two-level systems by ideal projective homodyne detection and feedback. For this purpose, the photon emission process is described on time scales much shorter than the lifetime of the excited state using a model based on Wigner-Weisskopf theory. The backaction of this emis

W. Hollik, J. I. Illana, S. Rigolin, D. Stöckinger

The MSSM predictions at the one-loop level for the weak-magnetic dipole moments of the $τ$ lepton and the $b$ quark are analysed. The entire supersymmetric parameter space is scannedwith the usual GUT constraint and common squark and slepton mass parameters. The real part of $a^W_τ$ is dominated by the chargino contribution, being the same order as the SM on

Steven Abel, Ben Allanach

The infra-red fixed points are determined for all the parameters of the MSSM. They dominate the renormalisation group running when the top-Yukawa is in the quasi-fixed point regime (i.e. large at the GUT scale). We examine this behaviour analytically, by solving the full set of one-loop renormalisation group equations in the approximation that the electrowea

Herbi Dreiner

I discuss the theoretical motivations for R-parity violation, review the experimental bounds and outline the main changes in collider phenomenology compared to conserved R-parity. I briefly comment on the effects of R-parity violation on cosmology.

Kazuo Hida

The effect of dimerization on the random antiferomagnetic Heisenberg chain with spin 1/2 is studied by the density matrix renormalization group method. The ground state energy, the energy gap distribution and the string order parameter are calculated. Using the finite size scaling analysis, the dimerization dependence of the these quantities are obtained. Th

P. Demetriou, S. Boffi, C. Giusti, F. D. Pacati

Final-state interactions in (e,e&#39;n) knockout reactions in the quasi-free region are studied by considering the multistep direct scattering of the ejectile nucleon. Primary and multiple particle emission are included within the same model and are found to become important with increasing excitation energy. Charge-exchange effects taken into account throug

Carsten Gundlach

We review the problem of finding an apparent horizon in Cauchy data (Sigma, g_ab, K_ab) in three space dimensions without symmetries. We describe a family of algorithms which includes the pseudo-spectral apparent horizon finder of Nakamura et al. and the curvature flow method proposed by Tod as special cases. We suggest that other algorithms in the family ma

David B. Fairlie

The infinite limit of Matrix Theory in 4 and 10 dimensions is described in terms of Moyal Brackets. In those dimensions there exists a Bogomol&#39;nyi bound to the Euclideanized version of these equations, which guarantees that solutions of the first order equations also solve the second order Matrix Theory equations. A general construction of such solutions

Stefano Mancini, Paolo Tombesi

We investigate the possibility of generating quantum macroscopic coherence phenomena by means of relativistic effects on a trapped electron.

Martin Bordemann, Nikolai Neumaier, Stefan Waldmann

In this paper we construct homogeneous star products of Weyl type on every cotangent bundle $T^*Q$ by means of the Fedosov procedure using a symplectic torsion-free connection on $T^*Q$ homogeneous of degree zero with respect to the Liouville vector field. By a fibrewise equivalence transformation we construct a homogeneous Fedosov star product of standard o

Alexander I. Molev, Bruce E. Sagan

We give a combinatorial rule for calculating the coefficients in the expansion of a product of two factorial Schur functions. It is a special case of a more general rule which also gives the coefficients in the expansion of a skew factorial Schur function. Multiplication rules for the Capelli operators and quantum immanants are also given.

Ruggero Maria Santilli

We submit the viewpoint that, perhaps, some of the controversies in gravitation occurred during this century are not due to insufficiencies of Einstein&#39;s field equations, but rather to insufficiencies in the mathematics used for their treatment. For this purpose we treat the same equations with the novel, broader isomathematics and related isominkowskian

R. K. Bansal, H. Sharda, Ashwani Kumar

Sum Rules equations for pick-up reactions are presented for the first time for the energy centroids of states both for the isospin T_< (\equiv T_0 - 1 \over 2) and T_> (\equiv T_0 + {1 \over 2}) of the final nucleus when a nucleon is picked up from a general multishell target state with isospin T_0. These equations contain two-body correlation terms, <H^{01}

Gerald A. Miller

Efforts to observe color transparency in the reactions: (e,e&#39;p), (p,pp) and coherent nuclear diffractive dissociation of pions into two jets are reviewed.

V. S. Uma Maheswari, J. N. De, S. K. Samaddar

The possibility of formation of a droplet phase (DP) inside a star and its consequences on the structural properties of the star are investigated. For nuclear matter (NM), an equation of state (EOS) based on finite range, momentum and density dependent interaction, and which predicts that neutron matter undergoes ferromagnetic transition at densities realisa

C. D. Fosco, G. L. Rossini, F. A. Schaposnik

We compute the exact canonically induced parity breaking part of the effective action for 2+1 massive fermions in particular Abelian and non Abelian gauge field backgrounds. The method of computation resorts to the chiral anomaly of the dimensionally reduced theory.

Chien-Hao Liu, U. Miami-Physics

The geometric aspect of Wick rotation in quantum field theory and its localization on manifolds are explored. After the explanation of the notion and its related geometric objects, we study the topology of the set of landing $W$ for Wick rotations and its natural stratification. These structures in two, three, and four dimensions are computed explicitly. We

Rainer Dick

A particle spectrum below the string scale in accordance with predictions from heterotic string theory yields a Planck mass $m_{Pl}=(8πG_N)^{-1/2}$ which exceeds the string scale by a factor $\simeq 61.9$. A Planck mass $m_{Pl}=2.43\times 10^{18}$ GeV then corresponds to a string scale $m_s=3.9\times 10^{16}$ GeV. Such a low value for the string scale in tur