September 1996 arXiv papers — page 12

Robert S. Maier, Daniel L. Stein

Suppose a two-dimensional dynamical system has a stable attractor that is surrounded by an unstable limit cycle. If the system is additively perturbed by white noise, the rate of escape through the limit cycle will fall off exponentially as the noise strength tends to zero. By analysing the associated Fokker-Planck equation we show that in general, the weak-

Hugo R. Christiansen, Fidel A. Schaposnik

We compute vacuum expectation values of products of fermion bilinears for two-dimensional Quantum Chromodynamics at finite flavored fermion densities. We introduce the chemical potential as an external charge distribution within the path-integral approach and carefully analyse the contribution of different topological sectors to fermion correlators. We show

Mario Hamuy, M. M. Phillips, Nicholas B. Suntzeff, Robert A. Schommer

The Calan/Tololo supernova survey has discovered ~30 Type Ia supernovae out to z~0.1. Using BVI data for these objects and nearby SNe Ia, we have shown that there exists a significant dispersion in the intrinsic luminosities of these objects. We have devised a robust chisquare minimization technique simultaneously fitting the BVI light curves to parametrize

P. Meszaros, M. J. Rees

We discuss the properties of magnetically dominated jet-like outflows from stellar mass black holes surrounded by debris tori resulting from neutron star disruption. These jets may have narrow cores (along the rotation axis) which are almost free of baryons and attain very high bulk Lorentz factors $\simg 10^6$. The jets give rise to a characteristic MeV to

Karl Landsteiner, John M. Pierre, Steven B. Giddings

We apply the method of confining phase superpotentials to N = 2 supersymmetric Yang-Mills theory with the exceptional gauge group G_2. Our findings are consistent with the spectral curve of the periodic Toda lattice, but do not agree with the hyperelliptic curve suggested previously in the literature. We also apply the method to theories with fundamental mat

Jerzy Lewandowski, Jacek Wiśniewski

The rank-2 sector of classical $3+1$ dimensional Ashtekar gravity is considered. It is found that the consistency of the evolution equations with the reality of the volume requires that the 3-surface of initial data is foliated by 2-surfaces tangent to degenerate triads. In turn, the degeneracy is preserved by the evolution. The 2-surfaces behave like $2+1$

Andrei G. Bytsko

Tensor operators associated with a given quantum Lie algebra admit a natural description in the R-matrix language. Here we employ the R-matrix approach to discuss the problem of fusion of tensor operators. The most interesting case is provided by the quantum WZNW model, where, by construction, we deal with sets of linearly independent tensor operators. In th

H. R. Karadayi, M. Gungormez

We give a general method to construct a complete set of linearly independent Casimir operators of a Lie algebra with rank N. For a Casimir operator of degree p, this will be provided by an explicit calculation of its symmetric coefficients $ g^{A_1,A_2,.. A_p}$. It is seen that these coefficients can be descibed by some rational polinomials of rank N. These

Lev Vaidman

Recently, several authors have criticized time-symmetrized quantum theory originated by the work of Aharonov et al. (1964). The core of this criticism was the proof, which appeared in various forms, showing that counterfactual interpretation of time-symmetrized quantum theory cannot be reconciled with the standard quantum theory. I argue here that the appare

Lev Vaidman

This is a philosophical paper in favor of the Many-Worlds Interpretation (MWI) of quantum theory. The concept of the ``measure of existence of a world'' is introduced and some difficulties with the issue of probability in the framework of the MWI are resolved. Brief comparative analyses of the Bohm theory and the Many-Minds Interpretation are given.

Yaw-Hwang Chen, Su-Long Nyeo, Yeou-Wei Yang

We employ the method of differential regularization to calculate explicitly the one-loop effective action of a bosonized $U_L(3)\times U_R(3)$ extended Nambu--Jona-Lasinio model consisting of scalar, pseudoscalar, vector and axial vector fields.

Gongru Lu, Yigang Cao, Zhaohua Xiong, Chongxing Yue

Correction to the $b\rightarrow sγ$ branching ratio in the multiscale walking technicolor model (MWTCM) is examined. For the original MWTCM, the correction is too large to explain the recent CLEO data. We show that if topcolor is further introduced, the branching ratio in the topcolor assisted MWTCM can be in agreement with the CLEO data for a certain range

M. I. Polikarpov

The abelian projection of lattice gluodynamics is reviewed. The main topics are: abelian and monopole dominance, monopole condensate as the disorder parameter, effective abelian Lagrangian, monopoles in the instanton field, Aharonov -- Bohm effect on the lattice.

Rama Cont, Didier Sornette

Random multiplicative processes $w_t =λ_1 λ_2 ... λ_t$ (with < λ_j > 0 ) lead, in the presence of a boundary constraint, to a distribution $P(w_t)$ in the form of a power law $w_t^{-(1+μ)}$. We provide a simple and physically intuitive derivation of this result based on a random walk analogy and show the following: 1) the result applies to the asymptotic ($t

Ken&#39;ichi Takano, K. Sano

Magnetic susceptibility measured for CaV$_4$O$_9$ is analyzed by a method with high temperature expansion. The analysis is consistent with the $g$-value which is close to 2 and is observed by an ESR experiment. Four exchange parameters in a two-dimensional Heisenberg model are determined to represent CaV$_4$O$_9$. All the exchange parameters are about 500 K

Marilyn A. Walker

This paper discusses the processes by which conversants in a dialogue can infer whether their assertions and proposals have been accepted or rejected by their conversational partners. It expands on previous work by showing that logical consistency is a necessary indicator of acceptance, but that it is not sufficient, and that logical inconsistency is suffici

Mario Hamuy, M. M. Phillips, Nicholas B. Suntzeff, Robert A. Schommer

BVRI light curves are presented for 27 Type Ia supernovae discovered during the course of the Calan/Tololo Survey and for two other SNe Ia observed during the same period. Estimates of the maximum light magnitudes in the B, V, and I bands and the initial decline rate parameter m15(B) are also given.

Mario Hamuy, M. M. Phillips, Nicholas B. Suntzeff, Robert A. Schommer

We present a family of six BVI template light curves for SNe Ia for days -5 and +80, based on high-quality data gathered at CTIO. These templates display a wide range of light curve morphologies, with initial decline rates of their B light curves between m15(B)=0.87 mag and 1.93 mag. We use these templates to study the general morphology of SNe Ia light curv

Mario Hamuy, M. M. Phillips, Robert A. Schommer, Nicholas B. Suntzeff

We examine the absolute luminosities of 29 SNe Ia in the Calan/Tololo survey. We confirm a relation between the peak luminosity of the SNe and the decline rate as measured by the light curve, as suggested by Phillips (1993). We derive linear slopes to this magnitude-decline rate relation in BV(I)kc colors, using a sample with Bmax-Vmax < 0.2 mag. The scatter

Jozef Dodziuk, Varghese Mathai

In this paper, we prove that the L^2 Betti numbers of an amenable covering space can be approximated by the average Betti numbers of a regular exhaustion, under some hypotheses. We also prove that some L^2 spectral invariants can be approximated by the corresponding average spectral invariants of a regular exhaustion. The main tool which is used is a general

D. Belitz, T. R. Kirkpatrick

The quantum ferromagnetic transition of itinerant electrons is considered. We give a pedagogical review of recent results which show that zero-temperature soft modes that are commonly neglected, invalidate the standard Landau-Ginzburg-Wilson description of this transition. If these modes are taken into account, then the resulting order parameter field theory

G. I. Lykasov, M. V. Rzjanin, W. Cassing

The production of antiprotons in $pp$ collisions is investigated close to threshold where experimental data about the total cross section are not available. We analyze the latter reaction within the LUND string model for inclusive $\bar{p}$ production and within the framework of a one-boson exchange model for the exclusive reaction $pp \rightarrow ppp\bar{p}

Alexander E. Lobkovsky, T. A. Witten

When a thin elastic sheet is confined to a region much smaller than its size the morphology of the resulting crumpled membrane is a network of straight ridges or folds that meet at sharp vertices. A virial theorem predicts the ratio of the total bending and stretching energies of a ridge. Small strains and curvatures persist far away from the ridge. We discu

Stefan Teufel, Karin Berndl, Detlef Dürr, Sheldon Goldstein

Motivated by Popescu&#39;s example of hidden nonlocality, we elaborate on the conjecture that quantum states that are intuitively nonlocal, i.e., entangled, do not admit a local causal hidden variables model. We exhibit quantum states which either (i) are nontrivial counterexamples to this conjecture or (ii) possess a new kind of more deeply hidden irreducib

E. Bergshoeff, M. de Roo, S. Panda

We show that a class of extremal four-dimensional supersymmetric ``high-branes&#39;&#39;, i.e. string and domain wall solutions, can be interpreted as intersections of four ten-dimensional Dirichlet branes. These $d=4$ solutions are related, via $T$-duality in ten dimensions, to the four-dimensional extremal Maxwell/scalar black holes that are characterized

V. S. Berezinsky, P. Blasi, V. S. Ptuskin

It is demonstrated that clusters of galaxies are able to keep cosmic rays for a time exceeding the age of the Universe. This phenomenon reveals itself by the production of the diffuse flux of high energy gamma and neutrino radiation due to the interaction of the cosmic rays with the intracluster gas. The produced flux is determined by the cosmological densit

Andreas Mielke

We study the problem of the phonon-induced electron-electron interaction in a solid. Starting with a Hamiltonian that contains an electron-phonon interaction, we perform a similarity renormalization transformation to calculate an effective Hamiltonian. Using this transformation singularities due to degeneracies are avoided explicitely. The effective interact

Priyamvada Natarajan, Jens Hjorth, Eelco van Kampen

We present the results of an attempt to adapt the distribution function formalism to characterize large-scale structures like clusters of galaxies that form in a cosmological N-body simulation. While galaxy clusters are systems that are not strictly in equilibrium, we show that their evolution can nevertheless be studied using a physically motivated extensio

J. Richert, D. Boose, A. Lejeune, P. Wagner

We investigate the thermodynamical content of a cellular model which describes nuclear fragmentation as a process taking place in an excited disordered system. The model which reproduces very well the size distribution of fragments does not show the existence of a first order phase transition.

T. K. Gaisser, R. J. Protheroe, T. Stanev

The bulk of the cosmic rays up to about 100 TeV are thought to be accelerated by the 1st order Fermi mechanism at supernova shocks, producing a power-law spectrum. Both electrons and protons should be accelerated, but their ratio on acceleration is not well known. Recently, the EGRET instrument on the Compton Gamma Ray Observatory has observed supernova remn

Hiroshi Suzuki

We propose a lattice formulation of the chiral fermion which maximally respects the gauge symmetry and simultaneously is free of the unwanted species doublers. The formulation is based on the lattice fermion propagator and composite operators, rather than on the lattice fermion action. The fermionic determinant is defined as a functional integral of an expec

M. B. Isichenko, A. V. Gruzinov

The long-time relaxation of ideal two dimensional magnetohydrodynamic turbulence subject to the conservation of two infinite families of constants of motion---the magnetic and the &#34;cross&#34; topology invariants--is examined. The analysis of the Gibbs ensemble, where all integrals of motion are respected, predicts the initial state to evolve into an equi

F. Gruemmer, B. Q. Chen, Z. Y. Ma, S. Krewald

Deformed Hartree-Fock-Bogoliubov calculations for finite nuclei are carried out. As residual interaction, a Brueckner G-matrix derived from a meson-exchange potential is taken. Phenomenological medium modifications of the meson masses are introduced. The binding energies, radii, and deformation parameters of the Carbon, Oxygen, Neon, and Magnesium isotope ch

A. Szanto de Toledo, B. V. Carlson, C. Beck, M. Thoenessen

The entrance-channel mass-asymmetry dependence of the compound nucleus formation time in light heavy-ion reactions has been investigated within the framework of semiclassical dissipative collision models. the model calculations have been succesfully applied to the formation of the $^{38}$Ar compound nucleus as populated via the $^{9}$Be+$^{29}$Si, $^{11}$B+$

Y. Meurice, S. Niermann, G. Ordaz

Using the hierarchical approximation, we discuss the cut-off dependence of the renormalized quantities of a scalar field theory. The naturalness problem and questions related to triviality bounds are briefly discussed. We discuss unphysical features associated with the hierarchical approximation such as the recently observed oscillatory corrections to the sc

T. Heinzl

We study the Gribov problem within a Hamiltonian formulation of pure Yang-Mills theory. For a particular gauge fixing, a finite volume modification of the axial gauge, we find an exact characterization of the space of gauge-inequivalent gauge configurations.

Samir D. Mathur

This note discusses some results on the non-BPS excitations of D-branes. We show that the excitation spectrum of a bound state of D-strings changes character when the length of the wrapping circle becomes less than $\sim g^{-1}\LS$. We review the observed relation between the low energy absorption cross-section of D-branes and the low energy absorption cross

Sumit R. Das, Gary Gibbons, Samir D. Mathur

In this paper we compute the low energy absorption cross-section for minimally coupled massles scalars and spin-$1/2$ particles, into a general spherically symmetric black hole in arbitrary dimensions. The scalars have a cross section equal to the area of the black hole, while the spin-$1/2$ particles give the area measured in a flat spatial metric conformal

Michael Dine

The past year has seen enormous progress in string theory. It has become clear that all of the different string theories are different limits of a single theory. Moreover, in certain limits, one obtains a new, eleven-dimensional structure known as $M$-theory. Strings with unusual boundary conditions, known as D-branes, turn out to be soliton solutions of str

Alan R. White

We argue that deep-inelastic diffractive scaling provides fundamental insight into the QCD Pomeron. The logarithmic scaling violations seen experimentally are in conflict with the scale-invariance of the BFKL Pomeron and with phenomenological two-gluon models. Instead the Pomeron appears as a single gluon at short-distances, indicating the appearance of a Su

Ira Z. Rothstein

In this talk I review the recent progress made in the calculations of quarkonia production in fixed target experiments. NRQCD organizes the calculations in a systematic expansion in $α_s$ and $v$, the relative velocity between the heavy quarks. Within this formalism there are octet contributions which are not included in the color singlet model. These contri

Laura Reina

We investigate the possibility of having sizable effects from flavor changing neutral currents at the tree level in a particular class of Two Higgs Doublet Models. Constraints from existing experimental information are discussed. Some interesting signals at the future generation of lepton colliders are illustrated.

David Atwood, Laura Reina, Amarjit Soni

A comprehensive phenomenological analysis of a two Higgs doublet model, with flavor changing scalar currents at the tree level, called model III, is presented. Constraints from existing experimental information especially on (Delta F)=2 processes are systematically incorporated. Constraints emerging from rare B-decays, Z-->b\bar b, and the ρparameter are als

L. Ya. Glozman

Beyond the spontaneous chiral symmetry breaking scale light and strange baryons should be considered as systems of three constituent quarks with an effective confining interaction and a chiral interaction that is mediated by the octet of Goldstone bosons (pseudoscalar mesons) between the constituent quarks.

K. Kusaka, G. Piller, A. W. Thomas, A. G. Williams

Deep-inelastic structure functions are studied within a covariant scalar diquark spectator model of the nucleon. Treating the target as a two-body bound state of a quark and a scalar diquark, the Bethe-Salpeter equation (BSE) for the bound state vertex function is solved in the ladder approximation. The valence quark distribution is discussed in terms of the

Hisakazu Minakata, Osamu Yasuda

We discuss constraints on a scenario of almost degenerate three-flavor neutrinos imposed by the solar and the atmospheric neutrino anomalies, hot dark matter, and neutrinoless double $β$ decays. It is found that in the Majorana version of the model the region with relatively large $θ_{13}$ is favored and a constraint on the CP violating phases is obtained.

David T. Barclay

In order that current and future renormalon results in QCD can be used to their full advantage it is important to understand how the Borel transforms of related functions are themselves related. For example, a change of renormalisation scheme can involve the inversion of a function; how is the transform of a function related to the transform of an inverse ?

Erwin Mirkes, Dieter Zeppenfeld

NLO corrections to jet cross sections in DIS at HERA are studied, with particular emphasis on the two jet final state. High jet transverse momenta are a good criterion for the applicability of fixed order perturbation theory. A ``natural&#39;&#39; scale choice is the average $k_T^B$ of the jets in the Breit frame, which suggest analyzing the data in differen

P. J. Bussey, B. B. Levchenko, A. Shumilin

We present prospects and requirements for the study at HERA of hard photon processes which generate high $p_T$ photons in the final state, and processes which generate Drell-Yan lepton pairs.

Gongru Lu, Yigang Cao, Zhaohua Xiong, Zhenjun Xiao

Applying the perturbative QCD (PQCD), we study the process $B_c\rightarrow D_s^*γ$ in the technicolor with a massless scalar doublet model (TCMLSM) recently presented by C. D. Carone and H. Georgi; and compare the results with that estimated in the standard model (SM). There are two mechanisms which contribute to the $B_c\rightarrow D_s^* γ$ process. One pro

Gongru Lu, Chongxing Yue, Yigang Cao, Zhaohua Xiong

Applying the perturbative QCD ( PQCD ) method, we study the decay $B_c\rightarrow D_s^*γ$ in the standard model and multiscale walking technicolor model. In the SM, we find that the contribution of weak annihilation is more important than that of the electromagnetic penguin. The presence of Pseudo-Goldstone-Bosons in the MWTCM leads to a large enhancement in

Zhenjun Xiao, Shunmin Liu, Xuelei Wang, Lingde Wan

Assuming that the actual values of $m_t$ and the data set ($Γ_b$, $Γ_h$, $Γ_Z$, $R_b$, $R_c$, $R_l$) are within their $1-σ$ errors as reported by CDF, D0 and by LEP Collaborations, the parameter $Δ^{new}_b$ which measures the nonoblique corrections on the $Zb\overline{b}$ vertex from new physics can be determined experimentally. According to the precision da

A. M. Green, P. S. Spencer, C. Michael

Sum rules -- relating the static quark potential V(R) to the spatial distribution of the action and energy in the colour fields of flux-tubes -- are applied in three ways: 1) To extract generalised beta-functions: 2) As a consistency check for the use of excited gluon flux-tubes and as an estimate of the quark self-energies: 3) To extract approximate sum rul

ZEUS Collaboration

The differential cross section $dσ/dt$ for elastic $ρ^0$ photoproduction, $γp \rightarrow ρ^0 p (ρ^0 \rightarrow π^+ π^-)$, has been measured in $ep$ interactions at HERA. The squared four-momentum exchanged at the proton vertex, $t$, has been determined directly by measuring the momentum of the scattered proton using the ZEUS Leading Proton Spectrometer (LP

Bahram Mashhoon, James C. McClune, Hernando Quevedo

We provide a physical basis for the local gravitational superenergy tensor. Furthermore, our gravitoelectromagnetic deduction of the Bel-Debever-Robinson superenergy tensor permits the identification of the gravitational stress-energy tensor. This {\it local} gravitational analog of the Maxwell stress-energy tensor is illustrated for a plane gravitational wa

Bahram Mashhoon, James C. McClune, Enrique Chavez, Hernando Quevedo

A class of solutions of the gravitational field equations describing vacuum spacetimes outside rotating cylindrical sources is presented. A subclass of these solutions corresponds to the exterior gravitational fields of rotating cylindrical systems that emit gravitational radiation. The properties of these rotating gravitational wave spacetimes are investiga

Neil J. Cornish

A purported black hole solution in (2+1)-dimensions is shown to be nothing more than flat space viewed from an accelerated frame.

Olga Perkovic, Karin A. Dahmen, James P. Sethna

Experimental systems with a first order phase transition will often exhibit hysteresis when out of equilibrium. If defects are present, the hysteresis loop can have different shapes: with small disorder the hysteresis loop has a macroscopic jump, while for large disorder the hysteresis loop is smooth. The transition between these two shapes is critical, with

Liang Fu, Lorenzo Resca

In a recent paper, Barrera and Fuchs [Phys. Rev. B 52, 3256 (1995)] provide a theory of electron energy loss in a random system of spheres. In this comment, we point out that the approach of Barrera and Fuchs (A) completely ignores magnetic excitations and retardation, which is inconsistent with the data of energy loss of fast electrons, (B) does not yield t

Alexander E. Lobkovsky

Large deformations of thin elastic plates and shells present a formidable problem in continuum mechanics which is generally intractable except by numerical methods. Conventional approaches break down in the limit of small plate thickness due to appearance of discontinuities in the solution which require boundary layer treatment. We examine a simple case of a

N. Turner, J. T. Nicholls, E. H. Linfield, K. M. Brown

The tunneling between two parallel two-dimensional electron gases has been investigated as a function of temperature $T$, carrier density $n$, and the applied perpendicular magnetic field $B$. In zero magnetic field the equilibrium resonant lineshape is Lorentzian, reflecting the Lorentzian form of the spectral functions within each layer. From the width of

Sean McNamara, Jean-Louis Barrat

We study the power input of a vibrating wall into a fluidized granular medium, using event driven simulations of a model granular system. The system consists of inelastic hard disks contained between a stationary and a vibrating elastic wall, in the absence of gravity. Two scaling relations for the power input are found, both involving the pressure. The tran

A. Kolezhuk, R. Roth, U. Schollwoeck

We study a frustrated antiferromagnetic isotropic Heisenberg $S=1$ chain using a variational ansatz and the DMRG. At $α_D=0.284(1)$, there is a disorder point of the second kind, marking the onset of incommensurate correlations in the chain. At $α_L=0.3725(25)$ there is a Lifshitz point, at which the excitation spectrum develops a doubly degenerate structure

J. Wang, Q. R. Zheng, H. Guo

The electric current conservation in a two-dimensional quantum wire under a time dependent field is investigated. Such a conservation is obtained as the global density of states contribution to the emittance is balanced by the contribution due to the internal charge response inside the sample. However when the global partial density of states is approximatel

Rene Plume, D. T. Jaffe, Neal J. Evans, J. Martin-Pintado

We have observed 150 regions of massive star formation, selected originally by the presence of a water maser, in the J = 5-4, 3-2, and 2-1 transitions of CS, and 49 regions in the same transitions of C$^{34}$S. Over 90% of the 150 regions were detected in the J = 2-1 and 3-2 transitions of CS and 75% were detected in the J=5-4 transition. We have combined th

Romeel Davé, Lars Hernquist, David H. Weinberg, Neal Katz

We use an automated Voigt-profile fitting procedure to extract statistical properties of the Ly$α$ forest in a numerical simulation of an $Ω=1$, cold dark matter (CDM) universe. Our analysis method is similar to that used in most observational studies of the forest, and we compare the simulations to recently published results derived from Keck HIRES spectra.

C. Waelkens, H. Van Winckel, L. B. F. M. Waters, E. J. Bakker

We present new observations of the central binary inside the Red Rectangle nebula. The detection of zinc in the optical spectrum confirms that the peculiar photospheric abundances are due to accretion of circumstellar gas. Grey brightness variations with the orbital period are observed. They are interpreted as being due to the variation of the scattering ang

Francesco Haardt, Piero Madau

The detection of a HeII absorption trough in the spectra of three high-redshift quasars provides new constraints on the spectral shape of the UV extragalactic background. The relative strengths of the observed flux decrements at the rest-frame wavelengths of 1216 and 304 A require a relatively soft radiation field at 4 ryd compared to 1 ryd. If the ionizing

S. Mereghetti, D. I. Cremonesi, F. Haardt, T. Murakami

GRS 1758-258 is one of the few persistent hard X-ray emitters (E>100 keV) in the Galaxy. Using the ASCA satellite, we have obtained the first detailed data on GRS 1758-258 in the 1-10 keV range, where previous observations were affected by confusion problems caused by the nearby strong source GX5-1. The spectrum is well described by a power law with photon i

Itziar Aretxaga, R. Cid Fernandes, R. J. Terlevich

The consistency of the Starburst model for AGN is tested using the optical variability observed in large data bases of QSOs. Theoretical predictions for the variability--luminosity relationship and structure function are presented and compared with observations. If QSOs follow a variability--wavelength relation as that observed in nearby AGN, the model prove

J. Franco, T. Plewa, G. Garcia-Segura

We present the main features in the evolution of the gas pressure in star forming regions, from the formation of the parental cloud to the moment when the region is pressurized by interacting stellar winds. The main processes for cloud destruction and the self-limiting properties of star formation are described. The high star forming efficiency in nuclear st

Marina Gibilisco

Many experimental evidences indicate the presence of a ionizing background radiation flux at large redshifts; in some previous works I suggested the possibility that this ionizing flux comes from the quantum evaporation of primordial black holes (PBHs). Here I discuss the constraints that the experimental measurements put upon the free parameters of this rei

Itziar Aretxaga

The continuum variability of optically selected Active Galactic Nuclei (AGN) is found to be consistent with that expected from a simple Poissonian process, in which the total luminosity of an object is produced by the multiple superposition of identical pulses. The energies, time-scales and rates of the pulses are found to be in the range of those expected f

David A. Buote, Guohong Xu

We examine the sensitivity of the spatial morphologies of galaxy clusters to Omega_0 and P(k) using high-resolution N-body simulations with large dynamic range. Variants of the standard CDM model are considered having different spatial curvatures, SCDM (Omega_0=1), OCDM (Omega_0=0.35), LCDM (Omega_0=0.35, lambda_0=0.65), and different normalizations, sigma_8

Francesco Haardt, Laura Maraschi, Gabriele Ghisellini

We discuss in detail the broad band X-ray variability expected in Seyfert galaxies in the framework of a Compton cooled corona model. Variations in the optical depth tau of the corona cause spectral changes in the Comptonized emission in the sense that the spectrum steepens and the temperature decreases with increasing tau. If the corona is pair dominated, t

V. S. Dhillon, T. R. Marsh, S. R. Duck, S. R. Rosen

We present infrared (0.97-2.45 micron) spectra of the intermediate polars PQ Gem (RE0751+14), BG CMi and EX Hya. The spectra show strong Paschen, Brackett and HeI emission lines from the accretion disc/stream. The infrared continua of PQ Gem and BG CMi can be represented by blackbodies of temperatures 4500 K and 5100 K, respectively, or by power-laws of the

Nobuo Arimoto, Kyoko Matsushita, Yuhri Ishimaru, Takaya Ohashi

We present estimates for the iron content of the stellar and diffused components of elliptical galaxies, as derived respectively from integrated optical spectra and from ASCA X-ray observations. A macroscopic discrepancy emerges between the expected iron abundances in the hot interstellar medium (ISM) and what is indicated by the X-ray observations, especial

Robert H. Brandenberger

Does inflation provide a compelling explanation for why the universe is so large, so flat, and so old, and a predictive theory of density perturbations? In this brief contribution (based on the role of the author as moderator of the discussion session on inflation), a list of some of the key issues confronting inflationary cosmology will be given, with the h

M. Giusti, J. Heintz, J. E. Morais, J. Morgenstern

We present a new method for solving symbolically zero--dimensional polynomial equation systems in the affine and toric case. The main feature of our method is the use of problem adapted data structures: arithmetic networks and straight--line programs. For sequential time complexity measured by network size we obtain the following result: it is possible to so

B. Bank, M. Giusti, J. Heintz, G. M. Mbakop

In this paper we apply for the first time a new method for multivariate equation solving which was developed in \cite{gh1}, \cite{gh2}, \cite{gh3} for complex root determination to the {\em real} case. Our main result concerns the problem of finding at least one representative point for each connected component of a real compact and smooth hypersurface. The

B. Bank, M. Giusti, J. Heintz, R. Mandel

The objective of this paper is to show how the recently proposed method by Giusti, Heintz, Morais, Morgenstern, Pardo \cite{gihemorpar} can be applied to a case of real polynomial equation solving. Our main result concerns the problem of finding one representative point for each connected component of a real bounded smooth hypersurface. The algorithm in \cit

A. C. Quillen, L. E. Kuchinski, J. A. Frogel, D. L. DePoy

We report on the discovery of a boxy/peanut shaped bulge in the highly inclined barred Seyfert 2 galaxy NGC~7582. The peanut shape is clearly evident in near infrared $JHK$ images but obscured by extinction from dust in visible $BVR$ images. This suggests that near infrared imaging surveys will discover a larger number of boxy/peanut morphologies than visibl

A. C. Quillen, J. A. Frogel

Outer rings are located at the greatest distance from the galaxy center of any feature resonant with a bar. Because of their large scale, their morphology is sensitive to the distribution of the dark matter in the galaxy. We introduce here how study of these rings can constrain the mass-to-light ratio of the bar, and so the percentage of dark matter in the c

R. Bijker, A. Leviatan

We consider an algebraic treatment of a three-body system. In particular, we develop the formalism for a system of three identical objects and discuss an application to nonstrange baryon resonances which are interpreted as vibrational and rotational excitations of an oblate symmetric top. We derive closed expressions for a set of elementary form factors that

Miguel Alcubierre

I consider the appearance of shocks in hyperbolic formalisms of General Relativity. I study the particular case of the Bona-Masso formalism with zero shift vector and show how shocks associated with two families of characteristic fields can develop. These shocks do not represent discontinuities in the geometry of spacetime, but rather regions where the coord

Jinwu Ye

We investigate a model where an impurity couples to both the spin and the flavor currents of the two channel conduction electrons. This model can be used as a prototype model of a magnetic impurity tunneling between two sites in a metal and of some heavy fermion systems where the ground state of the impurity has a fourfold degeneracy. The system is shown to

Jinwu Ye

We reinvestigate the two channel flavor anisotropic model (2CFAK) and one channel compacitified Kondo model (1CCK). For these two models, all the possible fixed points and their symmetries are identified; the finite size spectra, the electron conductivity and pairing susceptibility are calculated. It is shown that the only non-fermi liquid (NFL) fixed point

J. -L. Kneur

We investigate in some detail a &#34;variational mass&#34; expansion approach, generalized from a similar construction developed in the Gross-Neveu model, to evaluate the basic order parameters of the dynamical breaking of the $SU(2)_L \times SU(2)_R$ and $SU(3)_L \times SU(3)_R$ chiral symmetries in QCD. The method starts with a reorganization of the ordina

O. Krehl, R. Rapp, J. Speth

We study the influence of mass splitting between the charged and neutral pions and kaons in the Juelich meson exchange model for $ππ$ and $πη$ scattering. The calculations are performed in the particle basis, which permits the use of physical masses for the pseudoscalar mesons and a study of the distinct thresholds associated with the neutral and the charged

J. G. Russo

We point out an effect which may stabilize a supersymmetric membrane moving on a manifold with boundary, and lead to a light-cone Hamiltonian with a discrete spectrum of eigenvalues. The analysis is carried out explicitly for a closed supermembrane in the regularized $SU(N)$ matrix model version.

G. Kälbermann

A fluid of Skyrmions coupled to the dilaton field and the $ø$ meson field is considered. A mean field theory is developed in which the dilaton and the $ø$ field acquire a mean value determined by the Skyrmions. The influence of the background fields on the Skyrmion profile is determined and consequently the scaling properties of the Skyrmion follow. The mode

Teiji Kunihiro

The renormalization group method of Goldenfeld, Oono and their collaborators is applied to asymptotic analysis of vector fields. The method is formulated on the basis of the theory of envelopes, as was done for scalar fields. This formulation actually completes the discussion of the previous work for scalar equations. It is shown in a generic way that the me

V. N. Plechko

The notion of the integral over the anticommuting Grassmann variables (nonquantum fermionic fields) seems to be the most powerful tool in order to extract the exact analytic solutions for the 2D Ising models on simple and more complicated lattices, which is the subject of a discussion in this report.

T. Onogi, A. X. El-Khadra, B. J. Gough, G. M. Hockney

We present the recent Fermilab calculations of the masses of the light quarks, using tadpole-improved Sheikholeslami-Wohlert (SW) quarks. Various sources of systematic errors are studied. Our final result for the average light quark mass in the quenched approximation evaluated in the $\bar{MS}$ scheme is $\bar{m}_q(μ=2 GeV;n_f=0)= (m_u+m_d)/2=3.6 \pm 0.6 MeV

J. R. Klauder, P. Maraner

Starting with the generally well accepted opinion that quantizing an arbitrary Hamiltonian system involves picking out some additional structure on the classical phase space (the {\sl shadow} of quantum mechanics in the classical theory), we describe classical as well as quantum dynamics as a purely geometrical effect by introducing a {\sl phase space metric

J. Bertrand, M. Irac-Astaud

A differential calculus is set up on a deformation of the oscillator algebra. It is uniquely determined by the requirement of invariance under a seven-dimensional quantum group. The quantum space and its associated differential calculus are also shown to be invariant under a nine generator quantum group containing the previous one.

A. A. Vladimirov

We define a noncommutative algebra of four basic objects within a differential calculus on quantum groups: functions, 1-forms, Lie derivatives and inner derivations, as the cross-product algebra associated with Woronowicz&#39;s (differential) algebra of functions and forms. This definition properly takes into account the Hopf algebra structure of the Woronow

Carsten Schütt

Let $K$ be a convex body in $\Bbb R^{d}$ and $K_{t}$ its floating bodies. There is a polytope with at most $n$ vertices that satisfies $$ K_{t} \subset P_{n} \subset K $$ where $$ n \leq e^{16d} \frac{vol_{d}(K \setminus K_{t})}{t\ vol_{d}(B_{2}^{d})} $$ Let $K^{t}$ be the illumination bodies of $K$ and $Q_{n}$ a polytope that contains $K$ and has at most $n

Peter Pflug, Wlodzimierz Zwonek

In the paper we find effective formulas for the invariant functions, appearing in the theory of several complex variables, of the elementary Reinhardt domains. This gives us the first example of a large family of domains for which the functions are calculated explicitly.

Igor Kulikov

This thesis uses Path Integrals and Green&#39;s Functions to study Gravity, Quantum Field Theory and Statistical Mechanics, particularly with respect to: finite temperature quantum systems of different spin in gravitational fields; finite temperature interacting quantum systems in perturbative regime; self-interacting fermi models in non-trivial space-time o