August 1997 arXiv papers — page 15

Jonathan Fine

Each rule $f$ that assigns a vector $f(G)$ to an $(n+1)$-graph $G$ determines a class (or property) of $n$-manifold invariants. An invariant $v=v(M)$ is in this class if, for any triangulated manifold $|G|=M$, one has that $v(M)$ is a linear function of $f(G)$. This paper defines a flag vector $f(G)$ for $i$-graphs, whose associated invariants might be quant

J. Adam, Franz Gross, J. W. Van Orden

Meson exchange diagrams following from a lagrangian with off-shell meson-nucleon couplings are compared with those generated from conventional dynamics. The off-shell interactions can be transformed away with the help of a nucleon field redefinition. Contributions to to the $NN$- and $3N$-potentials and nonminimal contact e.m. meson-exchange currents are dis

Henning Heiselberg

Bose-Einstein correlations in relativistic heavy ion collisions and their dependence on the freeze-out condition in hydrodynamic models is compared to time-like freeze-out, where particles are emitted away only from the surface, i.e. space- vs. time-like freeze-out. The corresponding HBT radii are calculated for the two models emphasizing the difference in t

E864 Collaboration, T. A. Armstrong et al

We report on a search for metastable positively and negatively charged states of strange quark matter in Au+Pb reactions at 11.6 A GeV/c in experiment E864. We have sampled approximately six billion 10% most central Au+Pb interactions and have observed no strangelet states (baryon number A < 100 droplets of strange quark matter). We thus set upper limits on

Andrija Rasin

I discuss some general aspects of diagonalizing the quark mass matrices and list all possible parametrizations of the Cabibbo-Kobayashi-Maskawa matrix (CKM) in terms of three rotation angles and a phase. I systematically study the relation between the rotations needed to diagonalize the Yukawa matrices and various parametrizations of the CKM.

Nuno D. Antunes, Luis M. A. Bettencourt, Mark Hindmarsh

We present a full characterization of the phase transition in U(1) scalar field theory and of the associated vortex string thermodynamics in 3D. We show that phase transitions in the string densities exist and measure their critical exponents, both for the long string and the short loops. Evidence for a natural separation between these two string populations

C. Greub, T. Hurth

We give a summary about the various contributions which have to be calculated in order to obtain the next-to-leading logarithmic result for the branching ratio $BR(B \to X_s γ)$. Combining all these ingredients, which were obtained by different groups, a complete next-to-leading-logarithmic prediction of the inclusive decay rate was recently presented in the

G. L. Fogli, E. Lisi, A. Marrone

The available upward-going muon data from the Kamiokande, Baksan, MACRO, IMB, and SuperKamiokande experiments are reviewed and combined. Bounds on the neutrino mass and mixing parameters are derived for oscillations in two and three flavors. These bounds are not in significant conflict with the oscillation solution to the atmospheric neutrino flavor anomaly

J. Smith

We discuss three theoretical schemes to describe charm quark electroproduction.

Hai-Yang Cheng, B. Tseng

Nonfactorizable effects in charmless $B\to PP, VP$ decays can be lumped into the effective parameters a_i that are linear combinations of Wilson coefficients, or equivalently absorbed into the effective number of colors N_c. Naive factorization with N_c=3 fails to explain the CLEO data of $B^\pm \to ωK^\pm$, showing the first evidence for the importance of n

R. J. Creswick, F. T. Avignone, J. I. Collar, H. A. Farach

It is assumed that axions exist and are created in the Sun by Primakoff conversion of photons in the Coulomb fields of nuclei. Detection rates are calculated in germanium detectors due to the coherent conversion of axions to photons in the lattice when the incident angle fulfills the Bragg condition for a given crystalline plane. The rates are correlated wit

Robert N. Cahn, Mahiko Suzuki

We study final-state interactions in nonleptonic weak decays in statistical models by averaging over ensembles of strong interaction S-matrices. The models range from one with completely random strong interactions, which gives extensive mixing between physical states, to models with feeble final-state interactions, characterized by small phase shifts.

K. Kajantie, M. Laine, J. Peisa, A. Rajantie

Employing a non-perturbative gauge invariant definition of the Debye screening mass m_D in the effective field theory approach to finite T QCD, we use 3d lattice simulations to determine the leading O(g^2) and to estimate the next-to-leading O(g^3) corrections to m_D in the high temperature region. The O(g^2) correction is large and modifies qualitatively th

R. Foot

A simple alternative to the usual Pati-Salam model is proposed. The model allows quarks and leptons to be unified with gauge group $SU(4) \otimes SU(2)_L \otimes SU(2)_R$ at a remarkably low scale of about 1 TeV. Neutrino masses in the model arise radiatively and are naturally light.

G. J. Gounaris, J. Layssac, D. T. Papadamou, G. Tsirigoti

We discuss the sensitivity of the processes e+e- to b b(bar), e+e- to t t(bar) and gamma gamma to H to certain residual New Physics interactions affecting the heavy quark and Higgs boson sector. With a linear collider of 500 GeV, one should be able to detect and identify such effects with a characteristic scale up to 50 TeV.

K. C. Chou, Yue-Liang Wu

CP violation, fermion masses and mixing angles including that of neutrinos are studied in an SUSY SO(10)$\times Δ(48)\times$ U(1) model with small $\tan β$. The family symmetry $Δ(48)$ associated with a simple scheme of U(1) charge assignment on various fields concerned in superpotential leads to unique Yukawa coupling matrices with zero textures. Thirteen p

I. Campos

We investigate the properties of the Confinement-Higgs phase transition in the SU(2)-Higgs model. The system is shown to exhibit a transient behavior up to L=24 along which, the order of the phase transition cannot be discerned. In order to get a global vision on the problem, we have introduced a second (next-to-nearest neighbors) gauge-Higgs coupling (k2).

J. Hein

We investigate the SU(2) Higgs model at a Higgs Boson mass of \simeq 34 GeV for temperatures at the electroweak scale. We discuss in detail the critical temperature, the scalar field vacuum expectation value and the latent heat. We also consider for which temperatures the plasma can be regarded as radiation dominated.

Cinzia Talamonti

The aim of the NA48 experiment at the CERN SPS is to measure direct CP violation in neutral kaon decays thus determining the parameter $ε&#39;/ε$ with an accuracy of $2\times 10^{-4}$. The advantages of NA48 with respect to previous experiments are high statistics and reduced systematic effects. The principle of the experiment and the performance of the dete

D. J. Miller

This selection concentrates more on $γγ$ results, with some reference to the related HERA photoproduction data. Progress has been made on a wide range of topics, from $F_{2}^γ$ to the ``stickiness&#39;&#39; of glueball candidates, but many channels still need better statistics and/or a real photon target before they can match the comparable $ep$ studies.

G. P. Heath

Measurements of open charm production at HERA are reviewed. The paper covers both photoproduction and Deep Inelastic Scattering measurements from the ZEUS and H1 collaborations.

R. Gomez, R. L. Marsa, J. Winicour

We present a new method for treating the inner Cauchy boundary of a black hole spacetime by matching to a characteristic evolution. We discuss the advantages and disadvantages of such a scheme relative to Cauchy-only approaches. A prototype code, for the spherically symmetric collapse of a self-gravitating scalar field, shows that matching performs at least

Matthew J. Gursky, Claude LeBrun

The Yamabe Invariant of a smooth compact manifold is by definition the supremum of the scalar curvatures of unit-volume Yamabe metrics on the manifold. For an explicit infinite class of 4-manifolds, we show that this invariant is positive but strictly less than that of the 4-sphere. This is done by using spin^c Dirac operators to control the lowest eigenvalu

S. Berceanu

It is shown how the coherent states permit to find different geometrical objects as the geodesics, the conjugate locus, the cut locus, the Calabi's diastasis and its domain of definition, the Euler-Poincar\'e characteristic, the number of Borel-Morse cells, the Kodaira embedding theorem.

A. Arneodo, J. -F. Muzy, D. Sornette

Modelling accurately financial price variations is an essential step underlying portfolio allocation optimization, derivative pricing and hedging, fund management and trading. The observed complex price fluctuations guide and constraint our theoretical understanding of agent interactions and of the organization of the market. The gaussian paradigm of indepen

Masahiro Shiroishi, Miki Wadati

We discuss the integrable boundary conditions for the one-dimensional (1D) Hubbard Model in the framework of the Quantum Inverse Scattering Method (QISM). We use the fermionic R-matrix proposed by Olmedilla et al. to treat the twisted periodic boundary condition and the open boundary condition. We determine the most general form of the integrable twisted per

J-M Drouffe, C Godreche, F Camia

We consider the dynamics of a model introduced recently by Bialas, Burda and Johnston. At equilibrium the model exhibits a transition between a fluid and a condensed phase. For long evolution times the dynamics of condensation possesses a scaling regime that we study by analytical and numerical means. We determine the scaling form of the occupation number pr

E. Frey, F. Schwabl, S. Henneberger, O. Hartmann

We resolve a longstanding puzzle for the static and dynamic critical behavior of Gadolinium by a combined theoretical and experimental investigation. It is shown that the spin dynamics of a three dimensional ferromagnet with hcp lattice structure and a spin-spin interaction given by both exchange and dipole-dipole interaction belongs to a new dynamic univers

Peter Horsch, Janez Jaklic, Frank Mack

The electronic structure of perovskite manganese oxides is investigated in terms of a Kondo lattice model with ferromagnetic Hund coupling and antiferromagnetic exchange between $t_{2g}$-spins using a finite temperature diagonalization technique. Results for the dynamic structure factor are consistent with recent neutron scattering experiments for the bilaye

H. -W. Lee, V. Popkov, D. Kim

We study completely asymmetric 2-channel exclusion processes in 1 dimension. It describes a two-way traffic flow with cars moving in opposite directions. The interchannel interaction makes cars slow down in the vicinity of approaching cars in other lane. Particularly, we consider in detail the system with a finite density of cars on one lane and a single car

Eilon Brenner, Yacov Kantor

We perform an exact enumeration study of polymers formed from a (quenched) random sequence of charged monomers $\pm q_0$, restricted to a 2-dimensional square lattice. Monomers interact via a logarithmic (Coulomb) interaction. We study the ground state properties of the polymers as a function of their excess charge $Q$ for all possible charge sequences up to

Yao-Zhong Zhang, Huan-Qiang Zhou

The Bethe ansatz equations are presented for Bariev&#39;s correlated electron chain with boundaries. This is achieved by using the coordinate space Bethe ansatz method.

Michiyasu Mori, Masao Ogata, Hidetoshi Fukuyama

The possible modification of quantized conductance of one-dimensional doped Mott insulator, where the Umklapp scattering plays an important role, is studied based on the method by Maslov-Stone and Ponomarenko. At T=0 and away from half-filling, the conductance is quantized as $g=2e^2/h$ and there is no renormalization by Umklapp scattering process. At finite

Tom Chou

Bloch wavefunctions are used to derive dispersion relations for water wave propagation in the presence of an infinite array of periodically arranged surface scatterers. For one dimensional periodicity (stripes), band gaps for wavevectors in the direction of periodicity are found corresponding to multiple Bragg scattering. The dependence of these band gaps as

Gregory Falkovich, Vladimir Lebedev

We show that the tails of the single-point velocity probability distribution function (PDF) are generally non-Gaussian in developed turbulence. By using instanton formalism for the Navier-Stokes equation, we establish the relation between the PDF tails of the velocity and those of the external forcing. In particular, we show that a Gaussian random force havi

Thierry Dauxois, Stefano Ruffo, Alessandro Torcini

In the framework of the Fermi-Pasta-Ulam (FPU) model, we show a simple method to give an accurate analytical estimation of the maximal Lyapunov exponent at high energy density. The method is based on the computation of the mean value of the modulational instability growth rates associated to unstable modes. Moreover, we show that the strong stochasticity thr

David A. Neufeld, Jonas Zmuidzinas, Peter Schilke, Thomas G. Phillips

We report the first detection of interstellar hydrogen fluoride. Using the Long Wavelength Spectrometer (LWS) of the Infrared Space Observatory (ISO), we have detected the 121.6973 micron J = 2 - 1 line of HF in absorption toward the far-infrared continuum source Sagittarius B2. The detection is statistically significant at the 13 sigma level. On the basis o

K. B. Kwitter, R. B. C. Henry

This paper is the third in a series reporting on a study of carbon abundances in a carefully chosen sample of planetary nebulae representing a large range in progenitor mass and metallicity. We make use of the IUE Final Archive database containing consistently-reduced spectra to measure line strengths of C III] 1909 along with numerous other UV lines for the

M. A. T. Groenewegen

Some recent results on AGB research in the Magellanic Clouds are reviewed. Discussed are optical and IRAS based surveys, and recent results from the near-infrared DENIS survey, and ISO observations.

Deepa Majmudar, James H. Applegate

The abundances of beryllium and boron have been measured in halo stars of metallicities as low as [Fe/H] =-3. The observations show that the ratios Be/Fe and B/Fe are independent of metallicity and approximately equal to their solar values over the entire range of observed metallicity. These observations are in contradiction with the predictions of simple mo

Chris Mihos, John Dubinski, Lars Hernquist

We examine the effect of different dark matter halo potentials on the morphology and kinematics of tidals tails in a merger model of NGC 7252. We find that models of merging galaxies with low halo masses of Mh = 4-8 M{disk+bulge} (Mdb) can fit the observed morphology and kinematics of the NGC 7252 tails while galaxies with high mass halos (Mh = 16-32 Mdb) fa

F. T. Avignone, D. Abriola, R. L. Brodzinski, J. I. Collar

Results are reported of an experimental search for the unique, rapidly varying temporal pattern of solar axions coherently converting into photons via the Primakoff effect in a single crystal germanium detector. This conversion is predicted when axions are incident at a Bragg angle with a crystalline plane. The analysis of approximately 1.94 kg.yr of data fr

M. P. Allen, J. E. Horvath

The observed braking index n_{obs} which had been determined for a few young pulsars, had been found to differ from the expected value for a rotating magnetic dipole model. Also, the observational jerk parameter, determined for two of these pulsars, disagree with the theoretical prediction m_{obs} = 15 in both cases. We propose a simple model able to account

S. Van Eck, A. Jorissen, S. Udry, M. Mayor

HIPPARCOS trigonometrical parallaxes make it possible to compare the location of Tc-rich and Tc-poor S stars in the Hertzsprung-Russell (HR) diagram: Tc-rich S stars are found to be cooler and intrinsically brighter than Tc-poor S stars. The comparison with the Geneva evolutionary tracks reveals that the line marking the onset of thermal pulses on the asympt

D. Steeghs, E. T. Harlaftis, Keith Horne

We have found the first convincing evidence for spiral structure in the accretion disc of a close binary. The eclipsing dwarf nova binary IP Peg, observed during the end phase of a rise to outburst, shows strong Balmer and Helium emission lines in its spectra, with asymmetric double peaked velocity profiles produced in the accretion disc around the white dwa

M. Ulrich, A. Daum, G. Hermann, W. Hofmann

In order to better utilize the information contained in the shower images generated by imaging Cherenkov telescopes (IACTs) equipped with cameras with small pixels, images are fit to a parametrization of image shapes gained from Monte Carlo simulations, treating the shower direction, impact point, and energy as free parameters. Monte Carlo studies for a syst

M. J. Church, T. Dotani, M. Balucinska-Church, K. Mitsuda

We report results of analysis of the ASCA observation of the Low Mass X-ray Binary dipping source XB1916-053 made on 1993, May 2nd. We have shown that the spectra can be well fitted by the same two-component model previously used to give good explanations of the very different dip sources X1755-338 and X1624-490, consisting of point-source blackbody emission

J. K. Webb, R. F. Carswell, K. M. Lanzetta, R. Ferlet

Of the light elements, the primordial abundance of deuterium, (D/H)_p, provides the most sensitive diagnostic for the cosmological mass density parameter Omega_B. Recent high redshift (D/H) measurements are highly discrepant, although this may reflect observational uncertainties. The larger (D/H) values, which imply a low Omega_B and require the Universe to