November 1998 arXiv papers — page 8

Jordi Jose, Alain Coc, Margarita Hernanz

Classical novae eject significant amounts of matter into the interstellar medium, as a result of thermonuclear runaways. Nucleosynthesis associated with nova outbursts includes products from explosive H burning, such as 17O, 15N and 13C, and also radioactive species like 7Be, 22Na and 26Al. In this paper we report on new hydrodynamic calculations of nova out

M. Scodeggio, L. F. Olsen, L. N. da Costa

The results of a search for distant clusters of galaxies performed using the I-band data obtained by the ESO Imaging Survey (EIS) are presented. Cluster candidates are identified using a matched filter algorithm, that provides not only an objective detection criterion, but also the means to estimate the cluster redshift and richness. A preliminary sample of

J. Bohigas, J. L. Sauvageot, A. Decourchelle

Observations of the oxygen lines [OII]3729 and [OIII]5007 in the medium immediately beyond the Cygnus Loop supernova remnant were carried out with the scanning Fabry-Pérot spectrophotometer ESOP. Both lines were detected in three different directions - east, northeast and southwest - and up to a distance of 15 pc from the shock front. The ionized medium is i

D. J. Saikia

In the unified schemes for extragalactic radio sources, the quasars and BL Lac objects are intrinsically similar to the Fanaroff-Riley class II and I radio galaxies respectively, but appear to be different because they are viewed at different angles to the line-of-sight. The quasars and BL Lac objects are observed at small viewing angles while the radio gala

N. Ryde, K. Eriksson, B. Gustafsson

The 13-16 um region observed by the Infrared Space Observatory (ISO) of several ABG stars are discussed. We present and analyse spectra of seven M giants which show carbon dioxide features. To explain the features of the bands, we suggest they originate from two different circumstellar layers, one being a warm and high density layer close to the star, possib

S. Cassisi, V. Castellani, S. Degl'Innocenti, M. Salaris

We use evolutionary calculations presented in a recent paper (Cassisi et al. 1998) to predict B,V,I magnitudes for stars in galactic globulars. The effect of the adopted mixing length on stellar magnitudes and colors is discussed, showing that the uncertainty on such a theoretical parameter prevents the use of MS stars as bona fide theoretical standard candl

M. Kalinkov, I. Valtchanov, I. Kuneva

A bibliographic database will be constructed with the purpose to be a general tool for searching references for galaxy clusters. The structure of the database will be completely different from the available now databases as NED, SIMBAD, LEDA. Search based on hierarchical keyword system will be performed through web interfaces from numerous bibliographic sour

Elisabeth Vangioni-Flam, Michel Casse, Roger Cayrel, Jean Audouze

The primordial abundances of Deuterium, he4, and li7 are crucial to determination of the baryon density of the Universe in the framework of standard Big Bang nucleosynthesis (BBN). li6 which is only produced in tiny quantities and it is generally not considered to be a cosmological probe. However, recent major observational advances have produced an estimate

A. D. Schwope, G. Hasinger, R. Schwarz, F. Haberl

In the ROSAT Bright Survey (RBS) we have almost completely optically identified the brightest ~2000 high-galactic latitude sources from the ROSAT All-Sky Survey Bright Source Catalogue (1RXS). A small number of sources has empty X-ray error circles on optical images. ROSAT HRI follow-up observations of RBS1223 (=1RXS J130848.6+212708), a soft object with ext

M. Casse, E. Vangioni-Flam, R. Lehoucq

We analyse the photodisintegration of nuclei near the center of blazars, in particular PKS 0528+134. We show that this process could explain the recent observation of a high Al/Si ratio in a cloud on the line of sight of a distant quasar and we calculate the effect of this gamma irradiation on the abundance of deuterium, an isotope of the highest cosmologica

R. Chary, E. L. Wright

We present constraints on the density of halo dark matter candidates within the solar circle based on the anisotropy in the high energy gamma-ray background. The known galactic components of the gamma-ray background, in particular the inverse Compton component, have been estimated more accurately. We find the spectrum of the residual emission, after subtract

Z. Arzoumanian, J. M. Cordes, I. Wasserman

From considerations of spin evolution and kinematics in the galactic potential, we argue that the pulsars B1913+16, B1534+12, and B2127+11C may be younger than previously assumed, and we find that a lower bound on the formation and merger rate of close double neutron star binaries is $10^{-6.7} f_b^{-1} f_d^{-1}$ yr$^{-1}$, where $f_b$ is the beaming fractio

H. D. Tran, M. S. Brotherton, S. A. Stanford, W. van Breugel

Many ultraluminous infrared galaxies (ULIRGs) are powered by quasars hidden in the center, but many are also powered by starbursts. A simply diagnostic diagram is proposed that can identify obscured quasars in ULIRGs by their high-ionization emission lines ([O III] 5007/Hbeta >~ 5), and ``warm'' IR color (f_{25}/f_{60} >~ 0.25).

B. Gustafsson, T. Karlsson, E. Olsson, B. Edvardsson

Abundance analysis of carbon has been performed in a sample of 80 late F and early G type dwarf stars in the metallicity range -1.06 < [Fe/H] < 0.26 using the forbidden [C I] line at 8727 A. This line is presumably less sensitive to temperature, atmospheric structure and departures from LTE than alternative carbon criteria. We find that [C/Fe] decreases slow

Greg Kuperberg

The Mahler volume of a centrally symmetric convex body K is defined as M(K)= (Vol K)(Vol K^dual). Mahler conjectured that this volume is minimized when K is a cube. We introduce the bottleneck conjecture, which stipulates that a certain convex body K^diamond subset K X K^dual has least volume when K is an ellipsoid. If true, the bottleneck conjecture would s

Rosario Martin, Enric Verdaguer

We introduce a semiclassical Einstein-Langevin equation as a consistent dynamical equation for a first order perturbative correction to semiclassical gravity. This equation includes the lowest order quantum stress-energy fluctuations of matter fields as a source of classical stochastic fluctuations of the gravitational field. The Einstein-Langevin equation i

M. Magliocchetti, S. J. Maddox

We present a correlation function analysis for the catalogue of photometric redshifts obtained from the Hubble Deep Field image by Fernandez-Soto et al., 1998. By dividing the catalogue into redshift bins of width $Δz=0.4$ we measured the angular correlation function $w(θ)$ as a function of redshift up to $z\sim 4.8$. From these measurements we derive the tr

O. L. G. Peres, L. P. Freitas, R. Zukanovich Funchal

We investigate the sensitivity of some weak processes to the simplest extension of the Standard Model with Majorana neutrinos mixing in the leptonic sector. Values for mixing angles and masses compatible with several experimental accelerator data and the most recent neutrinoless double--$β$ decay limit were found.

Anthony N. Aguirre

Two groups have recently discovered a statistically significant deviation in the fluxes of high-redshift type Ia supernovae from the predictions of a Friedmann model with zero cosmological constant. In this Letter, I argue that bright, dusty, starburst galaxies would preferentially eject a dust component with a shallower opacity curve (hence less reddening)

Martin Goliath, George F. R. Ellis

Spatially homogeneous cosmological models with a positive cosmological constant are investigated, using dynamical systems methods. We focus on the future evolution of these models. In particular, we address the question whether there are models within this class that are de Sitter-like in the future, but are tilted.

George Chiladze, Adam F. Falk, Alexey A. Petrov

The recent discovery of the B_c meson by the CDF collaboration and proposed new experiments at Fermilab and CERN motivate new theoretical studies of the B_c system. Here we investigate the radiative leptonic decay B_c -> gamma l nu. This process is an important background to the annihilation process B_c -> l nu, which will be used to extract the B_c decay co

N. Pinto-Neto, E. Sergio Santini

The Bohm-de Broglie interpretation of quantum mechanics is applied to canonical quantum cosmology. It is shown that, irrespective of any regularization or choice of factor ordering of the Wheeler-DeWitt equation, the unique relevant quantum effect which does not break spacetime is the change of its signature from lorentzian to euclidean. The other quantum ef

Ingo Runkel

We consider A-series modular invariant Virasoro minimal models on the upper half plane. From Lewellen&#39;s sewing constraints a necessary form of the bulk and boundary structure constants is derived. Necessary means that any solution can be brought to the given form by rescaling of the fields. All constants are expressed essentially in terms of fusing (F-)

Juri Poutanen, Andrew C. Fabian

We present a model for the short timescale spectral variability of accreting black holes. It describes well the time-averaged spectra as well as temporal characteristics such as power-density spectrum, time/phase lags, and coherence function of Cygnus X-1. We assume that X/gamma-rays are produced in compact magnetic flares at radii < 100GM/c^2 from the centr

Jacques Demaret, Elisa Di Pietro

In the first part of the present paper, we show that O(d,d)-invariance usually known in a homogeneous cosmological background written in terms of proper time can be extended to backgrounds depending on one or several coordinates (which may be any space-like or time-like coordinate(s)). In all cases, the presence of a perfect fluid is taken into account and t

E. Guitter, C. Kristjansen, J. L. Nielsen

A random Eulerian triangulation is a random triangulation where an even number of triangles meet at any given vertex. We argue that the central charge increases by one if the fully packed O(n) model is defined on a random Eulerian triangulation instead of an ordinary random triangulation. Considering the case n -> 0, this implies that the system of random Eu

S. Munier, R. Peschanski

Using the solution of the BFKL equation including the leading and subleading conformal spin components, we show how the conformal invariance underlying the leading log 1/x expansion of perturbative QCD leads to elastic amplitudes described by two effective Pomeron singularities. One Pomeron is the well-known &#34;hard&#34; BFKL leading singularity while the

J. H. Field

The one-loop QCD effective charge $α_s^{eff}$ for quark-quark scattering is derived by diagrammatic resummation of the one-loop amplitude using an arbitary covariant gauge. Except for the particular choice of gauge parameter $ξ= -3$, $α_s^{eff}$ is found to {\it increase} with increasing physical scale, $Q$, as $\ln Q$ or $\ln^2 Q$. For $ξ= -3$, $α_s^{eff}$

Yu Shi

The famous gedanken experiments of quantum mechanics have played crucial roles in developing the Copenhagen interpretation. They are studied here from the perspective of standard quantum mechanics, with no ontological interpretation involved. Bohr&#39;s investigation of these gedanken experiments, based on the uncertainty relation with his interpretation, wa

J. H. Field

The massless fermion limit of QED is discussed. For on-shell renormalisation the high energy behaviour fixes no lower limit on the mass of the lightest fermion if the fine structure constant $α$ is allowed to vary. The choice of an arbitary (space-like) subtraction point does, however, fix a lower limit on the mass of the lightest fermion, for any subtractio

Miguel A. Munoz, Ronald Dickman, Alessandro Vespignani, Stefano Zapperi

We present generic scaling laws relating spreading critical exponents and avalanche exponents (in the sense of self-organized criticality) in general systems with absorbing states. Using these scaling laws we present a collection of the state-of-the-art exponents for directed percolation, dynamical percolation and other universality classes. This collection

Rahul Basu, D. Indumathi

We critically analyse the data available on the reduced cross-section in deeply inelastic $e p$ scattering from the H1 collaboration at HERA. We use available data on the longitudinal structure function to deduce the nature of $\d F_2/\d\ln Q^2$ at different $Q^2$ for fixed values of $x$ near $x \sim 10^{-4}$. We present the results in a manner which effecti

Arbab I. Arbab, A. Beesham

A cosmological model with variable G and Lambda is considered in the framework of Israel-Stewart-Hiscock (ISH) causal theory. Power law as well as inflationary solutions are obtained. The gravitational constant is found to increase with time.

Bang-Rong Zhou

The exact analytic solutions of the linearized Schwinger-Dyson equation of fermion self-energy are used to obtain the effective four-fermion and gauge coupling criticality curves for dynamical chiral symmetry breaking. The results show that when the zero-momentum gauge coupling $\alpha(0) < \alpha_0(0)$, the critical gauge coupling in the pure gauge interact

Daijiro Yoshioka

In a recent Letter, Yeh et al.[Phys. Rev. Lett. 82, 592 (1999)] have shown beautiful experimental results which indicate that the composite fermions with four flux quanta ($^4$CF) behave as fermions with mass and spin just like those with two flux quanta. They observed the collapse of the fractional quantum Hall gaps when the following condition is satisfied

W. Lee, D. Weingarten

For full QCD vacuum expectation values we construct an expansion in quark loop count and in powers of a coupling constant. The leading term in this expansion is the valence (quenched) approximation vacuum expectation value. Higher terms give corrections to the valence approximation. A test of the expansion is presented for moderately heavy quarks on a small

A. W. Strong, I. V. Moskalenko, O. Reimer

A new study of the diffuse Galactic gamma-ray continuum radiation is presented, using a cosmic-ray propagation model which includes nucleons, antiprotons, electrons, positrons, and synchrotron radiation. Our treatment of the inverse Compton (IC) scattering includes the effect of anisotropic scattering in the Galactic interstellar radiation field (ISRF) and a

Metin Gurses, Atalay Karasu

The recursion operator and bi-Hamiltonian formulation of the Drinfeld- Sokolov system are given

John R. Klauder

We study special systems with infinitely many degrees of freedom with regard to dynamical evolution and fulfillment of constraint conditions. Attention is focused on establishing a meaningful functional framework, and for that purpose, coherent states and reproducing kernel techniques are heavily exploited. Several examples are given.

K. V. Krutitsky, F. Burgbacher, J. Audretsch

The propagation of the electromagnetic field of a laser through a dense Bose gas is examined and nonlinear operator equations for the motion of the center of mass of the atoms are derived. The goal is to present a self-consistent set of coupled Maxwell-Bloch equations for atomic and electromagnetic fields generalized to include the atomic center-of-mass moti

Jun Luo, Xizhi Zeng

We consider two new quantum gate mechanisms based on nuclear spins in hyperpolarized solid $^{129}Xe$ and HCl mixtures and inorganic semiconductors. We propose two schemes for implementing a controlled NOT (CNOT) gate based on nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) from hyperpolarized solid $^{129}Xe$ and HCl mixtu

Matthew D. Jones, Gerardo Ortiz, David M. Ceperley

We present extensive and accurate calculations for the excited state spectrum of spin-polarized neutral helium in a range of magnetic field strengths up to $10^{12}$ G. Of considerable interest to models of magnetic white dwarf stellar atmospheres, we also present results for the dipole strengths of the low lying transitions among these states. Our methods r

N. Kuropatkin, R. Zukanovich Funchal

A Feed Forward Error Back Propagation Artificial Neural Network(ANN) algorithm is developed for electron/positron identification in a wide momentum region (10 - 300 GeV/c). The method was proposed for the Transition Radiation Detector of the E781 experiment at Fermilab. The package consists of two parts: - the program for the ANN training; - the particle cla

Su-Long Nyeo, I-Ching Yang

In this letter, we point out the inaccurate figures in a letter by Peyrard and Bishop, who investigated the statistical mechanics of a nonlinear model for DNA denaturation. We give the correct figures.

F. Theil, V. I. Levitas

How can a system in a macroscopically stable state explore energetically more favorable states, which are far away from the current equilibrium state? Based on continuum mechanical considerations we derive a Boussinesq-type equation which models the dynamics of martensitic phase transformations. The solutions of the system, which we refer to as microkinetica

Toshitaka Tatsumi, Masatomi Yasuhira

A new formulation is presented to treat thermal and quantum fluctuations around the kaon condensate on the basis of chiral symmetry; separating the zero-mode from the beginning and using the path-integral method, we can formulate the inclusion of fluctuations in a transparent way. Nucleons as well as kaons are treated in a self-consistent way to the one-loop

Harold W. Fearing, TRIUMF

In a recent preprint Cheon and Cheoun have derived from a chiral model an additional term, not usually appearing in the standard matrix element for radiative muon capture. Using that term they generate a large correction to the RMC spectrum which tends to resolve the problem caused by the too large value of $g_P$ found in the TRIUMF RMC experiment. In this c

J. Arrington

Inclusive electron scattering is measured with 4.045 GeV incident beam energy from C, Fe and Au targets. The measured energy transfers and angles correspond to a kinematic range for Bjorken $x > 1$ and momentum transfers from $Q^2 = 1 - 7 (GeV/c)^2$. When analyzed in terms of the y-scaling function the data show for the first time an approach to scaling for

P. Fratzl, O. Penrose, J. L. Lebowitz

Elastic interactions arising from a difference of lattice spacing between two coherent phases can have a strong influence on the phase separation (coarsening) of alloys. If the elastic moduli are different in the two phases, the elastic interactions may accelerate, slow down or even stop the phase separation process. If the material is elastically anisotropi

R. Coquereaux, A. O. Garcia, R. Trinchero

We consider the space M of NxN matrices as a reduced quantum plane and discuss its geometry under the action and coaction of finite dimensional quantum groups (a quotient of U_q(SL(2)), q being an N-th root of unity, and its dual). We also introduce a differential calculus for M: a quotient of the Wess Zumino complex. We shall restrict ourselves to the case

Mark S. Joshi, Antonio Sa Barreto

Scattering is defined on compact manifolds with boundary which are equipped with an asymptotically hyperbolic metric, $g.$ A model form is established for such metrics close to the boundary. It is shown that the scattering matrix at energy $ζ$ exists and is a pseudo-differential operator of order $2ζ+1 - \dim X.$ The symbol of the scattering matrix is then u

Aaron Robertson

We use finite fields and extend a result of Fan Chung to give eight new, nontrivial, lower bounds.

Wojciech Wieczorek

A smooth four manifold is of finite type $r$ if its Donaldson invariant satisfies D((x^2-4)^r)=0. We prove that every simply connected manifold is of finite type by using the structure of Donaldson invariants in the presence of immersed spheres. More precisely we prove that if a manifold X contains an immersed sphere with $p$ positive double points and a non

A. I. Molev

Olshanski&#39;s centralizer construction provides a realization of the Yangian for the Lie algebra gl(n) as a subalgebra in the projective limit of a chain of centralizers in the universal enveloping algebras. We give a modified version of this construction based on a quantum analog of Sylvester&#39;s theorem. We then use it to get an algebra homomorphism fr

Doron Zeilberger

Using the celebrated Morris Constant Term Identity, we deduce a recent conjecture of Chan, Robbins, and Yuen (math.CO/9810154), that asserts that the volume of a certain $n(n-1)/2$-dimensional polytope is given by the product of the first n-1 Catalan numbers.

Mark D. Gould, Yao-Zhong Zhang, Phillip S. Isaac

In this work we investigate several important aspects of the structure theory of the recently introduced quasi-Hopf superalgebras (QHSAs), which play a fundamental role in knot theory and integrable systems. In particular we introduce the opposite structure and prove in detail (for the graded case) Drinfeld&#39;s result that the coproduct $Δ&#39; \equiv (S\o

Mikhail G. Katz, Alexander I. Suciu

We outline the current state of knowledge regarding geometric inequalities of systolic type, and prove new results, including systolic freedom in dimension 4. Namely, every compact, orientable, smooth 4-manifold X admits metrics of arbitrarily small volume such that every orientable, immersed surface of smaller than unit area is necessarily null-homologous i

Friedemann Brandt, Ulrich Theis

We construct N=1 supersymmetric versions of four-dimensional Freedman-Townsend models and generalizations thereof found recently by Henneaux and Knaepen, with couplings between 1-form and 2-form gauge potentials. The models are presented both in a superfield formulation with linearly realized supersymmetry and in WZ gauged component form. In the latter formu

Thomas C. Kraan

In this paper, the metric on the moduli space of the k=1 SU(n) periodic instanton -or caloron- with arbitrary gauge holonomy at spatial infinity is explicitly constructed. The metric is toric hyperKaehler and of the form conjectured by Lee and Yi. The torus coordinates describe the residual U(1)^{n-1} gauge invariance and the temporal position of the caloron

N. D. Lambert, P. C. West

We review the relation between the classical dynamics of the M-fivebrane and the quantum low energy effective action for N=2 Yang-Mills theories. We also discuss some outstanding issues in this correspondence.

R S Ward

The Skyrme-Faddeev system, a modified O(3) sigma model in three space dimensions, admits topological solitons with nonzero Hopf number. One may learn something about these solitons by considering the system on the 3-sphere of radius R. In particular, the Hopf map is a solution which is unstable for R > \sqrt{2}.

S. V. Talalov

The model of D4 open string with non-Grassmann spinning variables is considered. The non-linear gauge, which is invariant both Poincaré and scale transformations of the space-time, is used for subsequent studies. It is shown that the reduction of the canonical Poisson structure from the original phase space to the surface of constraints and gauge conditions

K. A. Milton

It has been suggested by various authors that the `dynamical Casimir effect&#39; might prove responsible for the production of visible-light photons in the bubble collapse which occurs in sonoluminescence. Previously, I have argued against this point of view based on energetic considerations, in the adiabatic approximation. Those arguments have recently been

J. M. Borwein, D. J. Broadhurst

We identify 998 closed hyperbolic 3-manifolds whose volumes are rationally related to Dedekind zeta values, with coprime integers $a$ and $b$ giving $a/b vol(M)=(-D)^{3/2}/(2π)^{2n-4} (ζ_K(2))/(2ζ(2))$ for a manifold M whose invariant trace field $K$ has a single complex place, discriminant $D$, degree $n$, and Dedekind zeta value $ζ_K(2)$. The largest numer

A. V. Bratchikov

Conformal field theories based on $g/u(1)^d$ coset constructions where $g$ is a reductive algebra are studied.It is shown that the theories are equivalent to constrained WZNW models for $g.$ Generators of extended symmetry algebras and primary fields are constructed.

Kari Enqvist, John McDonald

In D-term inflation models, Affleck-Dine baryogenesis produces isocurvature density fluctuations. These can be perturbations in the baryon number, or, in the case where the present neutralino density comes directly from B-ball decay, perturbations in the number of dark matter neutralinos. The latter case results in a large enhancement of the isocurvature per

B. Borasoy

The baryon axial currents are calculated at one-loop order in heavy baryon chiral perturbation theory by employing both a cutoff and dimensional regularization. Data from the semileptonic baryon decays is used to perform a least-squares fit to the two axial couplings D and F of the effective Lagrangian. Predictions for the momentum dependent axial form facto

Stephen Godfrey, Jim Napolitano

We survey the current status of light meson spectroscopy. We begin with a general introduction to meson spectroscopy and and its importance in understanding the physical states of Quantum Chromo Dynamics (QCD). Phemenological models of hadron spectroscopy are described with particular emphasis on the constituent quark model and the qualitative features it pr

M. Majewski, G. V. Meshcheryakov, V. A. Meshcheryakov

Some experiments on LEAR obtained unusual behavior of the $p\bar p$ interaction near the threshold. The experiments on $p\bar p$ forvard scattering detected zeros and big variation of $ρ$ and at the same time a smooth rising of $σ_{tot}$ with lowing energy. Many models has difficulties in explanating this fact. In the PS170 experiment with a good statistical

M. C. Gonzalez-Garcia

I summarize here the results of a global fit to the full data set corresponding to 535 days of data of the Super-Kamiokande experiment as well as to all other atmosferic neutrino experiments in order to compare the most likely solutions to the atmospheric neutrino anomaly in terms of oscillations in the $ν_μ\to ν_e$, $ν_μ\to ν_τ$, and $ν_μ\to ν_s$ channels.

Albert Bramon, Marek Nowakowski

We extend the use of Bell-inequalities to $Φ\to K^0 \bar{K^0}$ decays by exploiting analogies and differences to the well-known and experimentally verified singlet-spin case. Contrasting with other analyses, our Bell-inequalities are violated by quantum mechanics and can strictly be derived from local realistic theories. In principle, quantum mechanics could

B. Ancochea, A. Bramon, M. Nowakowski

We analyze the premises of recent propositions to test local realism via Bell-inequalities using neutral kaons from $Φ$-resonance decays as entangled EPR-pairs. We pay special attention to the derivation of Bell-inequalities, or related expressions, for unstable and oscillating kaon `quasi-spin&#39; states and to the possibility of the actual identification

K. Gallmeister, B. Kaempfer, O. P. Pavlenko

We consider the intermediate mass continuum of dileptons (between $ϕ$ and $J/ψ$) in ultrarelativistic heavy--ion collisions. The thermal signal depends essentially on thermodynamic state parameters of the hottest parton stage as $(τ_iλ^q_iT_i^3)^2$ convoluted with an involved detector acceptance function. A refined analysis of the transverse pair momentum sp

S. Abdullin, F. Charles

We study the observability of the squarks and gluinos in CMS at LHC. Classical E_T^miss + jets final state as well as a number of additional multilepton signatures (0 leptons, 1 lepton, 2 leptons of the same sign, 2 leptons of the opposite sign and 3 leptons) are investigated . The detection of these sparticles relies on the observation of an excess of event

K. Gallmeister, B. Kaempfer, O. P. Pavlenko

The relation of the thermal dilepton signal from deconfined matter, resulting in central ultra-relativistic heavy-ion collisions at RHIC and LHC energies, to the background yields from the Drell-Yan process and correlated semileptonic decays of open charm and bottom mesons is analyzed. We demonstrate that very stringent kinematical cuts offer a chance to ide

Vishnu Mayya Bannur

We show that the extensively studied equation of state (EOS) of strongly coupled QED plasma fits the recent lattice EOS data of gluon plasma remarkably well, with appropriate modifications to take account of color degrees of freedom and running coupling constant. Hence we conclude that the quark gluon plasma near the critical temperature is a strongly couple

C. S. Kim, Jake Lee, W. Namgung

CP violation from physics beyond the Standard Model is investigated in $B_{l4}$ decays: $B\to Dπl\barν_l$. In the decay process, we include various excited states as intermediate states decaying to the final hadrons, $D+π$. We consider the semileptonic decay to a tau lepton family as well. The CP violation is implemented through complex scalar--fermion coupl

C. S. Kim, Jake Lee, W. Namgung

CP violation from physics beyond the Standard Model is investigated in $B_{l4}$ decays: $B\to Dπl\barν_l$. The semileptonic $B$-meson decay to a $D$-meson with an emission of single pion is analyzed with heavy quark effective theory and chiral perturbation theory. In the decay process, we include various excited states as intermediate states decaying to the

P. Desgrolard, M. Giffon, E. Martynov, E. Predazzi

The standard additive quark model and the ensuing counting rules are modified to take into account the quark-gluonic content of the Pomeron and of the secondary Reggeons. The result is that a much improved description of $pp, πp, γp$ and $γγ$ cross-sections is achieved.

E. G. Drukarev, M. G. Ryskin, V. A. Sadovnikova

We calculate the contribution of pions to the $\bar qq$-expectation value $κ(ρ)= <M|\bar qq|M>$ in symmetric nuclear matter. We employ exact pion propagator renormalized by nucleon-hole and isobar-hole excitations. Conventional straightforward calculation leads to the &#34;pion condensation&#34; at unrealistically small values of densities, causing even earl

U. -J. Wiese

A new non-perturbative approach to quantum field theory is proposed. Instead of performing a path integral over configurations of classical fields, D-theory works with discrete quantized variables. Classical spin fields are replaced by quantum spins, and classical gauge fields are replaced by quantum links. The classical fields of a d-dimensional quantum fie

Alessandro de Angelis

This talk deals with two topics in multiparticle dynamics investigated by means of the DELPHI detector at LEP. Related to the first topic, we have used the data collected at 183 GeV to measure the average charged particle multiplicity in $e^+e^- \to b\bar{b}$ events. The result is remarkably in agreement with QCD predictions, while it is more than two standa

ALEPH collaboration

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lo

ALEPH Collaboration

During 1997 the ALEPH experiment at LEP gathered 57pb^-1 of data at centre-of- mass energies near 183 GeV. These data are used to look for possible signals from the production of the Standard Model Higgs boson in the reaction e+e- -> HZ. No evidence of a signal is found in the data; seven events are selected, in agreement with the expectation of 7.2 events f

Esteban Calzetta

We consider a closed Friedmann-Robertson-Walker Universe driven by the back reaction from a massless, non-conformally coupled quantum scalar field. We show that the back-reaction of the quantum field is able to drive the cosmological scale factor over the barrier of the classical potential so that if the universe starts near zero scale factor (initial singul

Martin Goliath, Ulf S Nilsson, Claes Uggla

Einstein&#39;s field equations for timelike self-similar spherically symmetric perfect-fluid models are investigated. The field equations are rewritten as a first-order system of autonomous differential equations. Dimensionless variables are chosen in such a way that the number of equations in the coupled system is reduced as far as possible and so that the

Martin Goliath, Ulf S Nilsson, Claes Uggla

Einstein&#39;s field equations for spatially self-similar spherically symmetric perfect-fluid models are investigated. The field equations are rewritten as a first-order system of autonomous differential equations. Dimensionless variables are chosen in such a way that the number of equations in the coupled system is reduced as far as possible and so that the

Michael Grady

It is proposed that space is a four-dimensional Euclidean space with universal time. Originally this space was filled with a uniform substance, pictured as a liquid, which at some time became supercooled. Our universe began as a nucleation event initiating a liquid to solid transition. The universe we inhabit and are directly aware of consists of only the th

M. P. Anantram

There have been many studies of the linear response ac conductance of a double barrier resonant tunneling structure (DBRTS). While these studies are important, they fail to self-consistently include the effect of time dependent charge density in the well. In this paper, we calculate the ac conductance by including the effect of time dependent charge density

M. P. Anantram, Vwani P. Roychowdhury

We study the effect of metastable states on the relaxation process (and hence information propagation) in locally coupled and boundary-driven structures. We first give a general argument to show that metastable states are inevitable even in the simplest of structures, a wire. At finite temperatures, the relaxation mechanism is a thermally assisted random wal

A. S. Moskvin, Yu. D. Panov

One of the most exciting features of the hole centers CuO_{4}^{5-} in doped cuprates is an unusually complicated ground state which is the result of the electronic quasi-degeneracy. An additional hole, doped to the basic CuO_{4}^{6-} cluster with the b_{1g} hole can occupy both the same hybrid Cu3d-O2p orbital state resulting in a Zhang-Rice singlet ^1A_{1g}

D. Sornette, J. V. Andersen, P. Simonetti

We introduce a faithful representation of the heavy tail multivariate distribution of asset returns, as parsimonous as the Gaussian framework. Using calculation techniques of functional integration and Feynman diagrams borrowed from particle physics, we characterize precisely, through its cumulants of high order, the distribution of wealth variations of a po

A. Martin-Rodero, A. Levy Yeyati, J. C. Cuevas

We discuss the general transport properties of superconducting quantum point contacts. We show how these properties can be obtained from a microscopic model using nonequilibrium Green function techniques. For the case of a one-channel contact we analyze the response under different biasing conditions: constant applied voltage, current bias and microwave-indu

Michael Flohr

We consider quantum dots with a parabolic confining potential. The qualitative features of such mesoscopic systems as functions of the total number of electrons N and their total angular momentum J, e.g. magic numbers, overall symmetries etc., are derived solely from combinatoric principles. The key is one simple hypothesis about such quantum dots yielding a

K. Kubo, D. M. Edwards, A. C. M. Green, T. Momoi

This paper is a brief review of our recent studies concerning on magnetism and electronic states of lattice systems with Hund coupling. First we examined the effectiveness of the Hund coupling in realizing ferromagnetism in the doubly degenerate Hubbard model. One- and infinite-dimensional systems were studied and thereby dimensional dependence was discussed

Leonid Didukh, Vasyl Hankevych

In the previous papers (Journ. of Phys. Stud. 2, 362 (1998); cond-mat/9811213) we have studied metal-insulator transition in a generalized Hubbard model with correlated hopping at half-filling and zero temperature. The present paper is devoted to a further study of metal-insulator transition in this model,in particular, an investigation of temperature-induce

B. Groh

The surface free energy of ideal hard rods near curved hard surfaces is determined to second order in curvature for surfaces of general shape. In accordance with previous results for spherical and cylindrical surfaces it is found that this quantity is non-analytical when one of the principal curvatures changes signs. This prohibits writing it in the common H

Wei Ku, Adolfo G. Eguiluz

On the basis of a new ab initio, all-electron response scheme, formulated within time-dependent density-functional theory, we solve the puzzle posed by the anomalous dispersion of the plasmon linewidth in K. The key damping mechanism is shown to be decay into particle-hole pairs involving empty states of d-symmetry. While the effect of many-particle correlat

Youngho Park, Shoudan Liang, T. K. Lee

We have calculated the charge gap and spin gap for the two-chain Hubbard model as a function of the on-site Coulomb interaction and the interchain hopping amplitude. We used the density matrix renormalization group method and developed a method to calculate separately the gaps numerically for the symmetric and antisymmetric modes with respect to the exchange

Kouji Segawa, Yoichi Ando

The in-plane normal-state resistivity of Zn-doped YBa2Cu3O7-d single crystals is measured down to low temperatures by suppressing superconductivity with magnetic fields up to 18 T. Substitution of Cu with Zn in the CuO2 planes is found to induce carrier localization at low temperatures in &#34;clean&#34; samples with kF l > 5, where the mean free path l is l