August 1999 arXiv papers — page 4

Katrina Barron, Yi-Zhi Huang, James Lepowsky

Let $\mathfrak{g}$ be a Lie algebra in characteristic zero equipped with a vector space decomposition $\mathfrak{g}=\mathfrak{g}^-\oplus \mathfrak{g}^+$, and let $s$ and $t$ be commuting formal variables. We prove that the Campbell-Baker-Hausdorff map $C:s\mathfrak{g}^- [[s,t]]\times t\mathfrak{g}^+[[s,t]]\to s\mathfrak{g}^-[[s,t]]\oplus t\mathfrak{g}^+[[s,t

J. Koekoek, R. Koekoek

We look for spectral type differential equations satisfied by the generalized Jacobi polynomials which are orthogonal on the interval [-1,1] with respect to a weight function consisting of the classical Jacobi weight function together with point masses at the endpoints of the interval of orthogonality. In order to find explicit formulas for the coefficients

J. Koekoek, R. Koekoek

We find all spectral type differential equations satisfied by the symmetric generalized ultraspherical polynomials which are orthogonal on the interval [-1,1] with respect to the classical symmetric weight function for the Jacobi polynomials together with equal mass points at both ends of the interval of orthogonality. In order to find explicit formulas for

J. Koekoek, R. Koekoek

We look for differential equations satisfied by the generalized Jacobi polynomials which are orthogonal on the interval [-1,1] with respect to a weight function consisting of the classical Jacobi weight function together with point masses at the endpoints of the interval of orthogonality. In order to find explicit formulas for the coefficients of these diffe

J. Koekoek, R. Koekoek, H. Bavinck

We obtain all spectral type differential equations satisfied by the Sobolev-type Laguerre polynomials. This generalizes the results found in 1990 by the first and second author in the case of the generalized Laguerre polynomials defined by T.H. Koornwinder in 1984.

Herman Bavinck, Roelof Koekoek

In this paper we obtain a set of polynomials which are orthogonal with respect to the classical discrete weight function of the Charlier polynomials at which an extra point mass at x=0 is added. We construct a difference operator of infinite order for which these new discrete orthogonal polynomials are eigenfunctions.

Roelof Koekoek

We look for differential equations satisfied by the generalized Jacobi polynomials which are orthogonal on the interval [-1,1] with respect to the classical weight function for the Jacobi polynomials together with point masses at both endpoints. In the special symmetric case that both parameters are equal and also the two point masses are equal we find all d

Roelof Koekoek

We look for spectral type differential equations for the generalized Jacobi polynomials and for the Sobolev-Laguerre polynomials. We use a method involving computeralgebra packages like Maple and Mathematica and we will give some preliminary results.

Roelof Koekoek

We look for spectral type differential equations for the generalized Jacobi polynomials found by T.H. Koornwinder in 1984 and for the Sobolev-Laguerre polynomials. We introduce a method which makes use of computeralgebra packages like Maple and Mathematica and we will give some preliminary results.

J. Koekoek, R. Koekoek

We prove a formula for the nth power of the q-derivative operator at x=0 for every function whose nth derivative at x=0 exists. We give a proof in both the real variable and the complex variable case.

B. Pedrini, C. Schweigert, J. Walcher

We present new examples of maverick coset conformal field theories. They are closely related to conformal embeddings and exceptional modular invariants.

Mans Henningson

I review the computation of the conformal anomaly of a Wilson surface observable in free two-form gauge theory in six dimensions.

M. Gomes, L. C. Malacarne, A. J. da Silva

We study spin one particles interacting through a Chern-Simons field. In the Born approximation, we calculate the two body scattering amplitude considering three possible ways to introduce the interaction: (a) a Proca like model minimally coupled to a Chern-Simons field, (b) the model obtained from (a) by replacing the Proca's mass by a Chern-Simons term

Kost' Ilienko, Aleksandr Zheltukhin

We study the interaction between a tensionless (null) string and an antisymmetric background field B_{ab} using a 2-component spinor formalism. A geometric condition for the absence of such an interaction is formulated. We show that only one gauge-invariant degree of freedom of the field B_{ab} does not satisfy this condition. Identification of this degree o

G. P. Pronko

We discuss the construction of Baxter's Q-operator. The suggested approach leads to the one-parametric family of Q-operators, satisfying to the wronslian-type relations. Also we have found the generalization of Baxter operators, with defines the nondiagonal part of the monodromy.

Neil R. Constable, Robert C. Myers

We determine the spectrum of graviton excitations in the background geometry of the AdS soliton in p+2 dimensions. Via the AdS/CFT correspondence this corresponds to determining the spectrum of spin two excitations in the dual effective p-dimensional field theories For the cases of D3- and M5-branes these are the spin two glueballs of QCD_3 and QCD_4 respect

Bobby Eka Gunara

We define a semi-Hopf algebra which is more general than a Hopf algebra. Then we construct the supersymmetry algebra via the adjoint action on this semi-Hopf algebra. As a result we have a supersymmetry theory with quantum gauge group, i.e., quantised enveloping algebra of a simple Lie algebra. For the example, we construct the Lagrangian N=1 and N=2 supersy

Kaustubh Agashe

Supersymmetry solves the gauge hierarchy problem of the Standard Model if the masses of supersymmetric partners of the SM particles are close to the weak scale. In this thesis, we argue that the supersymmetric Standard Model, while avoiding the fine tuning in electroweak symmetry breaking, requires unnaturalness/fine tuning in some (other) sector of the theo

V. A. Korotkov, W. -D. Nowak

The physics case for a possible fixed target polarized nucleon-nucleon collision experiment at HERA is described. The experiment named HERA-N could be realized using an internal polarized gas target in the HERA polarized/unpolarized proton beam. A wide spectrum of nucleon spin structure problems could be investigated and the experiment would constitute a fix

Ernest Ma, G. Rajasekaran, Ion Stancu

We present a new and novel synthesis of all existing neutrino data regarding the disappearance and appearance of $\nu_e$ and $\nu_\mu$. We assume four neutrinos: $\nu_e, \nu_\mu, \nu_\tau$, as well as a heavier singlet neutrino $\nu_s$ of a few eV. The latter may decay into a massless Goldstone boson (the singlet Majoron) and a linear combination of the doub

E. H. Simmons

As the most recently discovered and heaviest quark, the top presents us with theoretical challenges. How are we to understand its properties within the larger effort to explain the origins of electroweak and flavor symmetry breaking ? This talk discusses some of the surprises the top quark may have in store for us and indicates how experiment may help us pin

E. Boos, V. Ilyin, A. Pukhov, M. Sachwitz

Assuming an integrated luminosity of 500 fb$^{-1}$ and a center-of-mass energy of 350 GeV, we examine the prospects for measuring branching fractions of a Standard Model-like Higgs boson with a mass of 160 GeV at the future linear \ee collider TESLA when the Higgs is produced via the Higgsstrahlung mechanism, \ee \pfr HZ. We study in detail the precisions ac

Jan Fischer, Ivo Vrkoc

We discuss the current use of the operator product expansion in QCD calculations. Treating the OPE as an expansion in inverse powers of an energy-squared variable (with possible exponential terms added), approximating the vacuum expectation value of the operator product by several terms and assuming a bound on the remainder along the euclidean region, we obs

Stefano Frixione, Michael Krämer, Eric Laenen

We calculate total and differential production rates of D* mesons in two-photon collisions at LEP2. We include full next-to-leading order QCD corrections, and perform an extensive study of the sensitivity of our predictions to variations of the renormalization scale, charm mass, photonic parton distribution set and fragmentation function. The results are com

H. Jirari, H. Kröger, C. Q. Huang, J. Q. Jiang

We suggest how to construct an effective low energy Hamiltonian via Monte Carlo starting from a given action. We test it by computing thermodynamical observables like average energy and specific heat for simple quantum systems.

O. Kaczmarek with J. Engels, F. Karsch, E. Laermann

We discuss the non-zero baryon number formulation of QCD in the quenched limit at finite temperature. This describes the thermodynamics of gluons in the background of static quark sources. Although a sign problem remains in this theory, our simulation results show that it can be handled quite well numerically. The transition region gets shifted to smaller te

M. Laine, K. Rummukainen

At finite temperatures around the electroweak phase transition, the thermodynamics of the MSSM can be described by a three-dimensional two Higgs doublet effective theory. This effective theory has a phase where CP is spontaneously violated. We study spontaneous CP violation with non-perturbative lattice simulations, and analyse whether one could end up in th

CDF Collaboration, F. Abe

We present a search for like-sign dielectron plus multijet events using 107 pb-1 of data in \ppbar collisions at $\sqrt{s} = 1.8$ TeV collected in 1992-95 by the CDF experiment. Finding no events that pass our selection, we set $σ\cdot Br$ limits on two SUSY processes that can produce this experimental signature: gluino-gluino or squark-antisquark production

L. C. Garcia de Andrade

An example is given of a plane topological torsion defect representing a cosmic wall double wall in teleparallel gravity.The parallel planar walls undergone a repulsive gravitational force due to Cartan torsion.This is the first example of a non-Riemannian double cosmic wall.It is shown that the walls oscillate with a speed that depends on torsion and on the

Michel Rigo

A generalization of numeration system in which the set N of the natural numbers is recognizable by finite automata can be obtained by describing a lexicographically ordered infinite regular language. Here we show that if P belonging to Q[x] is a polynomial such that P(N) is a subset of N then we can construct a numeration system in which the set of represent

Gavin E. Crooks

The Kawasaki nonlinear response relation, the transient fluctuation theorem, and the Jarzynski nonequilibrium work relation are all expressions that describe the behavior of a system that has been driven from equilibrium by an external perturbation. In contrast to linear response theory, these expressions are exact no matter the strength of the perturbation,

J. R. Simpson, H. D. Drew, V. N. Smolyaninova, R. L. Greene

We report on the optical properties of the hole-doped manganites La_0.7Ca_0.3MnO_3 and La_0.7Ca_0.3MnO_3. Transmission and reflection of thin films are measured in the infrared at temperatures from 10 - 150 K using Fourier-transform spectroscopy. The scattering rate and optical mass are obtained by fitting the far-infrared transmission to a Drude model. The

Herve M. Carruzzo, Clare C. Yu

We show that thermally activated interstitial and vacancy defects can lead to first order melting of a vortex lattice. We obtain good agreement with experimentally measured melting curve, latent heat, and magnetization jumps for YBCO and BSCCO. The shear modulus of the vortex liquid is frequency dependent and crosses over from zero at low frequencies to a fi

Alberto Franceschetti, Andrew Williamson, Alex Zunger

Using atomistic pseudopotential wave functions we calculate the electron and hole charging energies of InAs quantum dots. We find that the charging energies depend strongly on the dielectric constant epsilon_out of the surrounding material, and that when the latter is smaller than the dielectric constant of the dot the electron-electron and hole-hole interac

L. Vina

We review some of the newest findings on the spin dynamics of carriers and excitons in GaAs/GaAlAs quantum wells. In intrinsic wells, where the optical properties are dominated by excitonic effects, we show that exciton-exciton interaction produces a breaking of the spin degeneracy in two-dimensional semiconductors. In doped wells, the two spin components of

Francis W. Starr, Francesco Sciortino, H. Eugene Stanley

We present molecular dynamics simulations of the SPC/E model of water to probe the dynamic properties at temperatures from 350 K down to 190 K and pressures from 2.5GPa (25kbar) down to -300MPa (-3kbar). We compare our results with those obtained experimentally, both of which show a diffusivity maximum as a function of pressure. We find that our simulation r

I. P. McCulloch, M. Gulacsi, S. Caprara, A. Juozapavicius

We determine the boundary of the fully polarized ferromagnetic ground state in the one dimensional Kondo lattice model at partial conduction electron band filling by using a newly developed infinite size DMRG method which conserves the total spin quantum number. The obtained paramagnetic to ferromagnetic phase boundary is below $J \approx 3.5$ for the whole

S. Krishnamurthy, A. Tanguy, S. Roux

The depinning transition of a front moving in a time-independent random potential is studied. The temporal development of the overall roughness w(L,t) of an initially flat front, $w(t)\propto t^β$, is the classical means to have access to the dynamic exponent. However, in the case of front propagation in quenched disorder via extremal dynamics, we show that

Emilia La Nave, Antonio Scala, Francis W. Starr, Francesco Sciortino

We use the instantaneous normal mode approach to provide a description of the local curvature of the potential energy surface of a model for water. We focus on the region of the phase diagram in which the dynamics may be described by the mode-coupling theory. We find, surprisingly, that the diffusion constant depends mainly on the fraction of directions in c

Andrey V. Chubukov, Dirk. K. Morr, Girsh Blumberg

We show that the novel features observed in Raman experiments on optimally doped and underdoped Bi-2212 compounds in $B_{1g}$ geometry can be explained by a strong fermionic self-energy due to the interaction with spin fluctuations. We compute the Raman intensity $R(ω)$ both above and below $T_c$, and show that in both cases $R(ω)$ progressively deviates, wi

L. Moriconi

We propose a phenomenological model of vortex tube reconnection at high Reynolds numbers. The basic picture is that squeezed vortex lines, formed by stretching in the region of closest approach between filaments, interact like dipoles (monopole-antimonopole pairs) of a confining electrostatic theory. The probability of dipole creation is found from a canonic

D. S. Kainth, D. Richards, H. P. Hughes, M. Y. Simmons

We report angle-resolved Raman scattering observations of the temperature dependent Landau damping of the acoustic plasmon in an electron bilayer system realised in a GaAs double quantum well structure. Corresponding calculations of the charge-density excitation spectrum of the electron bilayer using forms of the random phase approximation (RPA), and the sta

R. Raupach, A. Klümper, F. Schönfeld

The theory by Cross and Fisher (CF) is by now commonly accepted for the description of the spin-Peierls transition within an adiabatic approach. The dimerization susceptibility as the essential quantity, however, is approximated by means of a continuum description. Several important experimental observations can not be understood within this scope. Using den

A. B. Dzyubenko, A. Yu. Sivachenko

For composite complexes -- quasi-two-dimensional (2D) charged magneto-excitons X- -- we propose a new exact classification of states, which is based on magnetic translations. We consider implications of this symmetry for magneto-optical transitions. It is shown, in particular, that in a translationally-invariant system with a simple valence band, the ground

F. Rullier-Albenque, P. A. Vieillefond, H. Alloul, A. W. Tyler

We report on a study of the influence of defects introduced in the CuO$_{2}$ planes of cuprates in a wide range of hole dopings n. T$_{c}$ and electrical resistivity $ρ(T)$ measurements have been performed on electron irradiated YBa$_{2}$Cu$_{3}$O$_{7-δ}$ and Tl$_{2}$Ba$_{2}$CuO$_{6+x}$ single crystals. A universal scaling between the decrease in T$_{c}$ and

M. D. Glinchuk, I. V. Kondakova

We present the theory of dielectric spectra allowing for homogeneous and inhomogeneous broadening mechanisms contributions. The dielectric absorption line shape for oscillators with memory and Debye type relaxors with distribution of, respectively, resonant frequencies and relaxation times (due to random electric fields distribution) has been calculated. The

Peter V. Coveney, Jonathan A. D. Wattis

We apply ideas from renormalization theory to models of cluster formation in nucleation and growth processes. We study a simple case of the Becker-Doring system of equations and show how a novel coarse-graining procedure applied to the cluster aggregation space affects the coagulation and fragmentation rate coefficients. A dynamical renormalization structure

S. Savrasov, MPI Stuttgart, G. Kotliar, Rutgers New Jersey

Correlation effects are important for making predictions in the delta phase of Pu. Using a realistic treatment of the intra-atomic Coulomb correlations we address the long-standing problem of computing ground state properties. The equilibrium volume is obtained in good agreement with experiment when taking into account Hubbard U of the order 4 eV. For this U

D. Alfe`, G. D. Price, M. J. Gillan

The free energy and other thermodynamic properties of hexagonal-close-packed iron are calculated by direct {\em ab initio} methods over a wide range of pressures and temperatures relevant to the Earth's core. The {\em ab initio} calculations are based on density-functional theory in the generalised-gradient approximation, and are performed using the proj

A. Aldea, A. Manolescu, V. Moldoveanu

A quantum-mechanical calculation of conductance in an open quantum dot is performed in the Landauer-Büttiker formalism using a tight binding Hamiltonian with direct Coulomb interaction. The charge distribution in the dot is calculated self-consistently as function of a gate potential, for various dot-leads couplings. The interaction is active only inside the

Tobias Brandes, Bernhard Kramer

We find an interference effect for electron-phonon interactions in coupled semiconductor quantum dots that can dominate the nonlinear transport properties even for temperatures close to zero. The intradot electron tunnel process leads to a `shake up' of the phonon system and is dominated by a double-slit-like interference effect of spontaneously emitted

Zh. S. Gevorkian, C. P. Chen, Chin-Kun Hu

We have considered X-ray radiation of a relativistic charged particle moving in a system consisting of microspheres distributed randomly in a dielectric material. A new mechanism based on the diffusional scattering of pseudophotons is suggested. The result leads to a stronger dependence of radiation intensity on the particle energy, than that predicted by th

G. A. Raggio

We show that the latest thermostatistical formalism based on the Havrda & Charvat-Daróczy-Tsallis entropy $S_q [ ρ] = (q-1)^{-1}(1- tr (ρ^q))$ proposed by Tsallis, Mendes and Plastino is {\em equivalent} to the first one proposed by Tsallis in 1988. Here, equivalent means: {\em the ``equilibrium'' state predicted by either formalism using $q$ leads t

H. Varvoglis, Ch. Vozikis, B. Barbanis

We study transport in a model perturbed integrable Hamiltonian system by calculating the volume, V(t), of elementary phase space cells visited by a trajectory, as a function of time. We use this function in order to "measure" the fractality of phase space. We argue that the "degree" of fractality is related to the well known difficulties in a

G. J. Chaitin

This is the transcript of a lecture given at UMass-Lowell in which I compare and contrast the work of Godel and of Turing and my own work on incompleteness. I also discuss randomness in physics vs randomness in pure mathematics.

I. L. Tregillis, T. W. Jones, Dongsu Ryu, Charles Park

We have applied an effective numerical scheme for cosmic-ray transport to 3D MHD simulations of jet flow in radio galaxies (see the companion paper by Jones et al. 1999). The marriage of relativistic particle and 3D magnetic field information allows us to construct a rich set of ``synthetic observations'' of our simulated objects. The information is

T. W. Jones, I. L. Tregillis, Dongsu Ryu

We have developed an economical, effective numerical scheme for cosmic-ray transport suitable for treatment of electrons up to a few hundreds of GeV in multidimensional simulations of radio galaxies. The method follows the electron population in sufficient detail to allow computation of synthetic radio and X-ray observations of the simulated sources, includi

B. R. Carlson, P. E. Dewdney, T. A. Burgess, R. V. Casorso

We describe the design of a correlator system for ground and space-based VLBI. The correlator contains unique signal processing functions: flexible LO frequency switching for bandwidth synthesis; 1 ms dump intervals, multi-rate digital signal-processing techniques to allow correlation of signals at different sample rates; and a digital filter for very high r

E. A. Richards

We have conducted a deep radio survey with the Very Large Array at 1.4 GHz of a region containing the Hubble Deep Field. This survey overlaps previous observations at 8.5 GHz allowing us to investigate the radio spectral properties of microjansky sources to flux densities greater than 40 $μ$Jy at 1.4 GHz and greater than 8 $μ$Jy at 8.5 GHz. A total of 371 so

M. Cappi, M. Persic, L. Bassani, A. Franceschini

BeppoSAX observations of the nearby archetypical starburst galaxies NGC253 and M82 are presented. Spectral analysis shows that the 2-10 keV spectra of both galaxies, extracted from the central 4' regions, are best fitted by a thermal emission model with kT~6-9 keV and metal abundances ~ 0.1-0.3 solar. The spatial analysis yields clear evidence that this

Eric M. Schlegel, Stuart Ryder, L. Staveley-Smith, R. Petre

We update the light curves from the X-ray, optical, and radio bandpasses which we have assembled over the past decade, and present two observations in the ultraviolet using the Hubble Space Telescope Faint Object Spectrograph. The HRI X-ray light curve is constant within the errors over the entire observation period. This behavior is confirmed in the ASCA GI

Helen E. M. Valentine, Will Saunders, Andy Taylor

We present a generalized version of the Path Interchange Zel'dovich Approximation (PIZA; Croft and Gaztanaga 1997; hereafter CG97), which may be used to reconstruct density and velocity fields from realistic galaxy redshift surveys. The original PIZA does not include the possibility of using galaxies in redshift space with a selection function. We map ga

G. Israelian, M. de Groot

P Cygni is a prototype for understanding mass loss from massive stars. This textbook star is known first of all because of two great eruptions in the 17th century. In the first half of this century it has given its name to a class of stars which are characterized by spectral lines consisting of nearly undisplaced emissions accompanied by a blue-displaced abs

G. Israelian, A. Lobel, M. R. Schmidt

High-resolution near-ultraviolet spectra of the yellow hypergiants HR 8752 and rho Cassiopeiae indicate high effective temperatures placing both stars near the T_eff border of the ``yellow evolutionary void''. At present, the temperature of HR 8752 is higher than ever. For this star we found Teff=7900+-200 K, whereas rho Cassiopeiae has Teff=7300+-20

G. Israelian

The effect of scattering processes in the continuum on the formation of spectral lines in a static atmosphere with an arbitrary distribution of the internal energy sources is investigated using Ambartsumian's principle of invariance. Spectral line profiles are calculated to illustrate the effect the assumption of the complete redistribution on atoms and

L. Ciotti, G. Bertin

In this paper we describe some analytical properties of the R^{1/m} law proposed by Sersic to categorize the photometric profiles of elliptical galaxies. In particular, we present the full asymptotic expansion for the dimensionless scale factor b(m) that is introduced when referring the profile to the standard effective radius. Surprisingly, our asymptotic a

L. Ciotti

There are observational and theoretical indications that both the visible (stars) and the dark matter density distributions in elliptical galaxies increase significantly up to the galactic center. I present here some analytical results obtained with the aid of self-consistent, spherically symmetric two component galaxy models. These results suggest the possi

A. Kashlinsky, J. C. Mather, S. Odenwald

The cosmic infrared background (CIB) radiation is the cosmic repository for energy release throughout the history of the universe. Using the all-sky data from the COBE DIRBE instrument at wavelengths 1.25 - 100 mic we attempt to measure the CIB fluctuations. In the near-IR, foreground emission is dominated by small scale structure due to stars in the Galaxy.

Soon-Wook Kim, J. Craig Wheeler, Shin Mineshige

Some effects of irradiation on time-dependent accretion-disk models for black hole X-ray novae are presented. Two types of irradiation are considered: direct irradiation from the inner hot disk and indirect irradiation as might be reflected by a corona or chromosphere above the disk. The shadowing effect of the time-dependent evolution of the disk height and

Leslie W. Looney, Lee G. Mundy, W. J. Welch

We present the results of a 2.7 mm continuum interferometric survey of 24 young stellar objects in 11 fields. The target objects range from deeply embedded Class 0 sources to optical T Tauri sources. This is the first sub-arcsecond survey of the 2.7 mm dust continuum emission from young, embedded stellar systems. The images show a diversity of structure and

D. Rigopoulou, H. W. W. Spoon, R. Genzel, D. Lutz

We present a low resolution mid-infrared spectroscopic survey of an unbiased sample of 62 Ultraluminous Infrared Galaxies (ULIRGs) using ISOPHOT-S on board ISO. For comparison we also present ISOPHOT-S spectra for 23 AGN and 15 starburst and normal galaxies. The line-to-continuum ratio of the 7.7 $μ$m PAH emission feature is used as a discriminator between s

Michal Chodorowski

I propose to compare the redshift-space density field directly to the REAL-SPACE velocity field. Such a comparison possesses all of the advantages of the conventional redshift-space analyses, while at the same time it is free of their disadvantages. In particular, the model-dependent reconstruction of the density field in real space is unnecessary, and so is

Akira Tomimatsu

The kinematic evolution of axisymmetric magnetic fields in rotating magnetospheres of relativistic compact objects is analytically studied, based on relativistic Ohm's law in stationary axisymmetric geometry. By neglecting the poloidal flows of plasma in simplified magnetospheric models, we discuss self-excited dynamos due to the frame-dragging effect (o

S. Vaughan, K. A. Pounds, J. Reeves, R. Warwick

We present simultaneous ASCA and RXTE observations of Ark 564, the brightest known ``narrow-line'' Seyfert 1 in the 2-10 keV band. The measured X-ray spectrum is dominated by a steep (Gamma~2.7) power-law continuum extending to at least 20 keV, with imprinted Fe K-line and -edge features and an additional ``soft excess'' below ~1.5 keV. The e

S. Wellstein, N. Langer

The progenitor evolution of the massive X-ray binary Wray 977 is investigated using new models of massive close binary evolution. These models yield constraints on the mass limit for neutron star/black hole formation in single stars, M_BH. We argue for quasi-conservative evolution in this system, and we find M_BH > 13...21 M_sun from the existence of a neutr

Ricard V. Sole, Bartolo Luque

In recent studies, new measures of complexity for nonlinear systems have been proposed based on probabilistic grounds, as the LMC measure (Phys. Lett. A {\bf 209} (1995) 321) or the SDL measure (Phys. Rev. E {\bf 59} (1999) 2). All these measures share an intuitive consideration: complexity seems to emerge in nature close to instability points, as for exampl

Kok-Kiong Loh, Isabelle Kraus, Robert B. Meyer

The textures associated with a point defect centered in a circular domain of a thin film with XY-like ordering have been analyzed. The family of equilibrium textures, both stable and metastable, can be classified by a new radial topological number in addition to the winding number of the defect. Chiral textures are supported in an achiral system as a result

Fu-Guang Cao, A. I. Signal

We obtained two analytical constraints on the $η$-$η^\prime$ mixing parameters by considering two-photon decays of $η$ and $η^\prime$ [$η(η^\prime) \ra γγ$], and productions of $η$ and $η^\prime$ in the $e^+ e^-$ scattering at large momentum transfer ($Q^2 \ra \infty$). Using the data given in the PDG98 for the decay processes and recent CLEO measurements on

Yu-Chung N. Cheng, Lawrence M. Krauss

We have selected 42 elliptical galaxies from the literature and estimated their velocity dispersions at the effective radius ($σ_{\re}$) and at 0.54 effective radii ($\vff$). We find by a dynamical analysis that the normalized velocity dispersion of the dark halo of an elliptical galaxy $\vdm$ is roughly $σ_{\re}$ multiplied by a constant, which is almost in

Korkut Bardakci

We investigate a class of models in 1+1 dimensions with four fermion interaction term. At each order of the perturbation expansion, the models are ultraviolet finite and Lorentz non-invariant. We show that for certain privileged values of the coupling constants, Lorentz symmetry is restored, and indeed the model turns out to be conformally invariant. This ph

Tianjun Li

If the universe is (or a slice of) $AdS_5$ space with 3-branes, the 5-dimensional GUT scale on each brane can be indetified as the 5-dimensional Planck scale, but, the 4-dimensional Planck scale is generated from the low 4-dimensional GUT scale exponentially in our world. The 4-dimensional GUT scales and Planck scale are related to the 5-dimensional GUT scal

H. -Th. Janka, Th. Eberl, M. Ruffert, C. L. Fryer

Hydrodynamic simulations of the merger of stellar mass black hole - neutron star binaries (BH/NS) are compared with mergers of binary neutron stars (NS/NS). The simulations are Newtonian, but take into account the emission and backreaction of gravitational waves. The use of a physical nuclear equation of state allows us to include the effects of neutrino emi

Valter Moretti

Completing the results obtained in a previous paper, we prove the symmetry of Hadamard/Seeley-deWitt off-diagonal coefficients in smooth $D$-dimensional Lorentzian manifolds. To this end, it is shown that, in any Lorentzian manifold, a sort of ``local Wick rotation'' of the metric can be performed provided the metric is a locally analytic function of

Z. Aouissat, G. Chanfray, P. Schuck, J. Wambach

The influence of a dropping sigma-meson mass on previously calculated in-medium pion-pion correlations in the J=I=0 (sigma-meson) channel is investigated. It is found that the invariant-mass distribution around the vacuum threshold experiences a further strong enhancement with respect to standard many-body effects. The relevance of this result for the explan

M. Oertel, M. Buballa, J. Wambach

We investigate the effect of mesonic fluctuations on the pion propagator in the Nambu-Jona-Lasinio (NJL) model by explicitly taking into account 1/N_c corrections. Because of the non-renormalizability of the model we have to regularize the meson loops with an independent cutoff parameter Lambda_M. Whereas for moderate values of Lambda_M the pion properties c

Tom Theuns, Joop Schaye, Martin Haehnelt

We investigate the dependence of QSO Lyman-alpha absorption features on the temperature of the absorbing gas and on the amplitude of the underlying dark matter fluctuations. We use high-resolution hydrodynamic simulations in cold dark matter dominated cosmological models. In models with a hotter intergalactic medium (IGM), the increased temperature enhances

H. Kitatani, A. Sinada

A new method to numerically calculate the $n$th moment of the spin overlap of the two-dimensional $\pm J$ Ising model is developed using the identity derived by one of the authors (HK) several years ago. By using the method, the $n$th moment of the spin overlap can be calculated as a simple average of the $n$th moment of the total spins with a modified bond

Martin Bojowald

Three different methods to quantize the spherically symmetric sector of electromagnetism are presented: First, it is shown that this sector is equivalent to Abelian BF-theory in four spacetime dimensions with suitable boundary conditions. This theory, in turn, is quantized by both a reduced phase space quantization and a spin network quantization. Finally, t

Stefano Bertolini, Marco Fabbrichesi

A new lattice estimate of K -> 2 pi transitions claims, contrary to all other computations, that the hadronic matrix element for the gluon penguin operator Q_6 has opposite sign and, in addition, is much larger than the vacuum saturation approximation. We comment under what conditions (if any) it is possible to reconcile this lattice result with the experime

N. Sh. Izmailian, Chin-Kun Hu, F. Y. Wu

It is shown that the percolation model of hydrogen-bonded crystals, which is a 6-vertex model with bond defects, is completely equivalent with an 8-vertex model in an external electric field. Using this equivalence we solve exactly a particular 6-vertex model with bond defects. The general solution for the Bethe-like lattice is also analyzed.

J. A. Miranda, M. Widom

Parallel flow in a Hele-Shaw cell occurs when two immiscible liquids flow with relative velocity parallel to the interface between them. The interface is unstable due to a Kelvin-Helmholtz type of instability in which fluid flow couples with inertial effects to cause an initial small perturbation to grow. Large amplitude disturbances form stable solitons. We

Mohab Abou-Zeid, Bernard de Wit, Dieter Lust, Hermann Nicolai

The connection between IIA superstring theory compactified on a circle of radius R and IIB theory compactified on a circle of radius 1/R is reexamined from the perspective of N=2, D=9 space-time supersymmetry. We argue that the consistency of IIA/B duality requires the BPS states corresponding to momentum and winding of either of the type-II superstrings to

Nobuki Maeda

Using the von Neumann lattice formalism, we study compressible anisotropic states around the half-filled Landau levels in the quantum Hall system. In these states the unidirectional charge density wave (UCDW) state seems to be the most plausible state. The charge density profile and Hartree-Fock energy of the UCDW are calculated self-consistently. The wave l

C. H. Hyun, T. -S. Park, D. -P. Min

We report a next-to-leading-order (NLO) chiral perturbation theory calculation of the neutron-proton scattering cross section in the ${}^1S_0$ channel using a cut-off regularization. The inclusion of two-pion exchanges in the irreducible diagrams -- or potential -- figuring at NLO is found to be important in enlarging the domain of validity of the effective

Masahiro Takada, Eiichiro Komatsu, Toshifumi Futamase

We investigate the weak gravitational lensing effect due to the large-scale structure of the universe on two-point correlations of local maxima ({\em hotspots}) in the 2D sky map of the cosmic microwave background (CMB) anisotropy. According to the Gaussian random statistics as most inflationary scenarios predict, the hotspots are discretely distributed with

J. Corson, R. Mallozzi, J. Orenstein, J. N. Eckstein

We report measurements of anamolously large dissipative conductivities in BiSrCaCuO(2212) at low temperatures. We have measured the complex conductivity of BSCCO thin films at 100-600 GHz as a function of doping from the underdoped to the overdoped state. At low temperatures there exists a residual dissipative conductivity which scales with the T=0 superflui

Chun-Woo Lee

Recently, we showed that eigenphase shifts and eigentime delays near a resonance for a system of one discrete state and two continua are functionals of the Beutler-Fano formula using appropriate dimensionless energy units and line profile indices and identified parameters responsible for the avoided crossing of eigenphase shifts and eigentime delays and also

M. S. Hussein, A. F. R. de Toledo Piza, O. K. Vorov

We construct a three-dimensional analytically soluble model of the nonlinear effects in Coulomb excitation of multiphonon Giant Dipole Resonances (GDR) based on the SU(2,1) algebra. The full 3-dimensional model predicts further enhancement of the Double GDR (DGDR) cross sections at high bombarding energies. Enhancement factors for DGDR measured in thirteen d

D. Zschiesche, P. Papazoglou, Ch. W. Beckmann, S. Schramm

An extended chiral SU(3) model is applied to the description of dense, hot and strange hadronic matter. The degrees of freedom are the baryon octet and decuplet and the spin-0 and spin-1 meson multiplets. The parameters of the model are fitted to the hadron masses in vacumm, infinite nuclear matter properties and soft pion theorems. At high densities the app

R. Beck

Tagged linearly polarized photons have been used at the Mainz Microtron MAMI for simultaneous measurements of the p(\vecγ,p)π^0 and p(\vecγ,π^+)n reaction channels to study the γN \to Δ(1232) transition. The energy dependence of the magnetic dipole M_{1+}^{3/2} and electric quadrupole E_{1+}^{3/2} amplitudes have been extracted from these data in the photon