October 1997 arXiv papers — page 5

A. Rosly, K. Selivanov

We present here an explicit self-dual classical solution of the type of perturbiner in gravity. This solution is a generating function for tree gravitational form-factors with all on-shell gravitons in the same helicity state.

K. Selivanov

The perturbiner approach to the multi-gluonic amplitudes in Yang-Mills theory is reviewed.

Pran Nath, R. Arnowitt

Implications of the effects of non-universalities of the soft SUSY breaking parameters on dark matter and on physics at colliders is discussed.

A. K. Likhoded, S. R. Slabospitsky

We propose a modification of the mechanism of charmed quarks fragmentation into $D$ mesons in hadronic collisions. It is shown that the distinction in valence quark distributions in the initial $π^{\pm}$ and $K^{\pm}$ mesons leads to different inclusive spectra of $D$ and $D_s$ mesons produced in $π^{\pm}$ and $K^{\pm}$ beams.

A. Hebecker

In the present talk diffraction in deep inelastic scattering is discussed in the framework of the semiclassical approach. The main emphasis is on the possibility of a consistent semiclassical description of both hard and soft colour singlet exchange processes. This approach allows the comparison of hard and soft colour neutralization in diffractive electropr

Han Meng, Ma Wen-Gan, Han Liang, Jiang Yi

We present the calculation of the supersymmetric QCD correction to $W γ$ production process in polarized proton-antiproton collisions at the TeV energy region. We find that the correction can reach 1.2% at parton level with favorable mass values of squarks and gluino, which is comparable with the virtual correction part of the conventional QCD. The productio

Lior M. Burko

We study the Cauchy horizon (CH) singularity of a spherical charged black hole perturbed nonlinearly by a self-gravitating massless scalar field. We show numerically that the singularity is weak both at the early and at the late sections of the CH, where the focusing of the area coordinate $r$ is strong. In the early section the metric is almost Reissner-Nor

Asok K. Sen

We study the phase distribution of the complex reflection coefficient in different configurations as a disordered 1D system evolves in length, and its effect on the distribution of the 4-probe resistance $R_4$. The stationary ($L \to \infty$) phase distribution is almost always strongly non-uniform and is in general double-peaked with their separation decayi

Sergei Skorik

Applications of the integrable system techniques to the non-equilibrium transport problems are discussed. We describe one-dimensional electrons tunneling through a point-like defect either by the s-d exchange (Kondo) mechanism, or via the resonanse level (Anderson) mechanism. These models are potential candidates to be solved exactly in the presence of arbit

Ravi P. Pilla, Abraham Loeb

Cosmological $γ$-ray bursts originate from relativistic winds. Temporal fluctuations in the wind velocity can give rise to internal shocks which dissipate a significant fraction of the wind kinetic energy. Part of the energy dissipated is transferred to the electrons through Fermi acceleration. If the post shock fluid is strongly magnetized, the relativistic

S. Degl'Innocenti, B. Ricci

We consider a wide class of solar models with mixed core. Most of these models can be excluded as the predicted sound speed profile is in sharp disagreement with helioseismic constraints. All the remaining models predict $^7$Be and/or $^7$B neutrino fluxes at least as large as those of SSMs. In conclusion, helioseismology shows that a mixed solar core cannot

Kwok Lung Chan, Utpal Chattopadhyay, Pran Nath

Naturalness bounds on weak scale supersymmetry in the context of radiative breaking of the electro-weak symmetry are analyzed. In the case of minimal supergravity it is found that for low tanβand for low values of fine tuning Phi, where Phi is defined essentially by the ratio μ^2/M_Z^2 where μis the Higgs mixing parameter and M_Z is the Z boson mass, the all

Dae Kwan Kim, K. G. Klimenko

The three-dimensional Gross-Neveu model in $R^{1} \times S^{2}$ spacetime is considered at finite particles number density. We evaluate an effective potential of the composite scalar field $σ(x)$, which is expressed in terms of a scalar curvature $R$ and nonzero chemical potential $μ$. We then derive the critical values of $(R,μ)$ at which the system undergo

A. N. Ivanov, N. I. Troitskaya

The partial widths of the decays $D^+_s \to ϕπ^+$ and $D^+_s \to π^+ π^+ π^-$ - nonresonant are computed within the effective quark model with chiral symmetry involving Heavy quark effective theory (HQET) and Chiral perturbation theory at the quark level (CHPT)$_q$ with linear realization of chiral U(3) x U(3) symmetry. It is shown that for the explanation o

Martin D. Kruskal, Nalini Joshi, Rod Halburd

The integrability (solvability via an associated single-valued linear problem) of a differential equation is closely related to the singularity structure of its solutions. In particular, there is strong evidence that all integrable equations have the Painlevé property, that is, all solutions are single-valued around all movable singularities. In this exposit

Boris F. Samsonov

The Darboux transformation operator technique is applied to construct exactly solvable anharmonic singular oscillator potentials and to study their coherent states. Classical system corresponding to a transformed quantum system is constructed with the help of the coherent states technique. It is shown that at classical level the Darboux transformation may be

Lee Smolin

A Lorentz covariant quantization of membrane dynamics is defined, which also leaves unbroken the full three dimensional diffeomorphism invariance of the membrane. Among the applications studied are the reduction to string theory, which may be understood in terms of the phase space and constraints, and the interpretation of physical,zero-energy states. A matr

A. N. Ivanov, N. I. Troitskaya

The coupling constants of D*D$π$ and B*B$π$ strong interactions are computed in the effective quark model with chiral symmetry incorporating Heavy quark effective theory (HQET) and Chiral perturbation theory at the quark level with linear realization of chiral U(3)XU(3) symmetry. We predict g(D*D$π$) = 5.2 and g(B*B$π$) = 14.3. The corrections of large heavy

Hideyuki Abe

The interaction between the hyperon and the nucleon is investigated in the SU(3) Skyrme model. The static potential, which is expanded in terms of the modified SU(3) rotation matrices, is obtained for several orientations with the Atiyah-Manton ansatz. The interaction is calculated for the NN, \LambdaN, and \SigmaN systems. The medium-range attraction of the

R. Bernabei, P. Belli, F. Montecchia, W. Di Nicolantonio

The DAMA experiments are running deep underground in the Gran Sasso National Laboratory. Several interesting results have been achieved so far. Here a maximum likelihood method to search for the WIMP annual modulation signature is discussed and applied to a set of preliminary test data collected with large mass highly radiopure NaI(Tl) detectors. Various rel

Paul Hickson

Compact groups of galaxies have posed a number of challenging questions. Intensive observational and theoretical studies are now providing answers to many of these, and at the same time, are revealing unexpected new clues about the nature and role of these systems. Most compact groups contain a high fraction of galaxies having morphological or kinematical pe

V. B. Shenoy, Tin-Lun Ho

We have calculated the first and second sound modes of a dilute interacting Bose gas in a spherical trap for temperatures ($0.6<T/T_{c}<1.2$) and for systems with $10^4$ to $10^8$ particles. The second sound modes (which exist only below $T_{c}$) generally have a stronger temperature dependence than the first sound modes. The puzzling temperature variations

Maarten Golterman

In this talk, I address the comparison between results from lattice QCD computations and Chiral Perturbation Theory (ChPT). I briefly discuss how ChPT can be adapted to the much-used quenched approximation and what it tells us about the special role of the $η&#39;$ in the quenched theory. I then review lattice results for some quantities (the pion mass, pion

Nelson Caldwell, Taft E. Armandroff, G. S. Da Costa, Patrick Seitzer

We have obtained HST WFPC2 images through the F555W and F814W filters of two M81 group dE&#39;s: BK5N and a new system, designated F8D1. The resulting color-magnitude diagrams show the upper two magnitudes of the red giant branch. Surface brightness and total magnitude measurements indicate that BK5N and F8D1 have similar central surface brightness (24.5 and

R. L. Jaffe

I review the ways that have been proposed to measure the quark transversity distribution in the nucleon. I then explain a proposal, developed by Xuemin Jin, Jian Tang and myself, to measure transversity through the final state interaction between two mesons ($\pi\pi$, $K \bar K$, or $\pi K$) produced in the current fragmentation region in deep inelastic scat

M. Faber, A. N. Ivanov, N. I. Troitskaya

The mechanism of a confining medium is investigated within the Nambu-Jona-Lasinio (NJL) approach. It is shown that a confining medium can be realized in the bosonized phase of the NJL model due to vacuum fluctuations of both fermion and Higgs (scalar fermion-antifermion collective excitation) fields. In such an approach there is no need to introduce Dirac st

W. Buchmuller, M. Plumacher

We study CP asymmetries in lepton-number violating two-body scattering processes and show how they are related to CP asymmetries in the decays of intermediate massive Majorana neutrinos. Self-energy corrections, which do not contribute to CP asymmetries in two-body processes, induce CP violating couplings of the intermediate Majorana neutrinos to lepton-Higg

Daniel Fisher, Pierre Le Doussal, Cecile Monthus

Sinai&#39;s model of diffusion in one-dimension with random local bias is studied by a real space renormalization group which yields asymptotically exact long time results. The distribution of the position of a particle and the probability of it not returning to the origin are obtained, as well as the two-time distribution which exhibits &#34;aging&#34; with

Harvendra Singh

In this report we obtain explicit string-like solutions of equations of motion of massive heterotic supergravity recently obtained by Bergshoeff, Roo and Eyras. We also find consistent string source which can be embedded in these backgrounds when space-time dimension is greater than or equal to six.

M. S. Fayache, E. Moya de Guerra, P. Sarriguren, Y. Y. Sharon

The presence of not yet detected intruder states in $^{8}Be$ e.g. a $J=2^{+}$ intruder at 9 $MeV$ excitation would affect the shape of the $β^{\mp }$-delayed alpha spectra of $^{8}Li$ and $^{8}B$. In order to test the plausibility of this assumption, shell model calculations with up to $4\hbar ω$ excitations in $^{8}Be$ (and up to $2\hbar ω$ excitations in $

H. T. Ozer

We give an extension of Casimir of Casimir $\cal{WA_N}$ algebras including a vertex operator which depends on non-simple roots of $A_{N-1}$.

A. Arbona, C. Bona, J. Carot, L. Mas

Initial data corresponding to spacetimes containing black holes are considered in the time symmetric case. The solutions are obtained by matching across the apparent horizon different, conformally flat, spatial metrics. The exterior metric is the vacuum solution obtained by the well known conformal imaging method. The interior metric for every black hole is

Haye Hinrichsen, Mickael Antoni

Recently B. Derrida [Phys. Rev. E 55, 3705 (1997)] introduced a numerical technique that allows one to measure the fraction of persistent spins in a coarsening nonequilibrium system at finite temperature. In the present work we extend this method in a way that domain walls can be clearly identified. To this end we consider three replicas instead of two. As a

Larus Thorlacius

Solutions of Born-Infeld theory, representing strings extending from a Dirichlet p-brane, are also solutions of the higher derivative generalization of the Born-Infeld equations defining an exact open string vacuum configuration.

Uros Seljak

We present a unified approach to the problems of reconstruction of large-scale structure distribution in the universe and determination of the underlying power spectrum. These have often been treated as two separate problems and different analysis techniques have been developed for both. We show that there exists a simple relation between the optimal solutio

Limin Lu, Wallace L. W. Sargent, Thomas A. Barlow

Galactic chemical evolution model calculations indicate that there should be considerable scatter in the observed N/O ratios at a fixed metallicity (O/H) for galaxies with very low metallicities due to the delayed release of primary N from intermediate mass stars relative to that of O from short-lived massive stars. Moreover, the scatter should increase prog

Nalini Joshi

In this paper, we find all possible asymptotic behaviours of the solutions of the second Painlevé equation $y&#39;&#39;=2y^3+xy +α$ as the parameter $α\to\infty$ in the local region $x\llα^{2/3}$. We prove that these are asymptotic behaviours by finding explicit error bounds. Moreover, we show that they are connected and complete in the sense that they corre

Clio Cresswell, Nalini Joshi

The discrete Painlevé I equation (dP$\rm_I$) is an integrable difference equation which has the classical first Painlevé equation (P$\rm_I$) as a continuum limit. dP$\rm_I$ is believed to be integrable because it is the discrete isomonodromy condition for an associated (single-valued) linear problem. In this paper, we derive higher-order difference equations

R. Conte

The ``Painlevé analysis&#39;&#39; is quite often perceived as a collection of tricks reserved to experts. The aim of this course is to demonstrate the contrary and to unveil the simplicity and the beauty of a subject which is in fact the theory of the (explicit) integration of nonlinear differential equations. To achieve our goal, we will not start the expos

Paul B. Slater

The three and five-dimensional convex sets of two-level complex and quaternionic quantum systems are studied in the Bayesian thermostatistical framework introduced by Lavenda. Associated with a given parameterization of each such set is a quantum Fisher (Helstrom) information matrix. The square root of its determinant (adopting an ansatz of Harold Jeffreys)

H. M. Wiseman

The phase of a single-mode field can be measured in a single-shot measurement by interfering the field with an effectively classical local oscillator of known phase. The standard technique is to have the local oscillator detuned from the system (heterodyne detection) so that it is sometimes in phase and sometimes in quadrature with the system over the course

Jerzy Lukierski, Valeryi N. Tolstoy

Cartan-Weyl basis for the quantum affine superalgebra U_q(^osp(1|2)) is constructed in an explicit form.

Antonina N. Fedorova, Michael G. Zeitlin

In this paper we present the applications of methods from wavelet analysis to polynomial approximations for a number of accelerator physics problems. In the general case we have the solution as a multiresolution expansion in the base of compactly supported wavelet basis. The solution is parametrized by the solutions of two reduced algebraical problems, one i

M. C. Firpo, Y. Elskens

A system of N particles eN=(x1,v1,...,xN,vN) interacting self-consistently with M waves Zn=An*exp(iTn) is considered. Hamiltonian dynamics transports initial data (eN(0),Zn(0)) to (eN(t),Zn(t)). In the limit of an infinite number of particles, a Vlasov-like kinetic equation is generated for the distribution function f(x,v,t), coupled to envelope equations fo

I. M. Pavlichenkov

All the known cases of the $ΔI=4$ bifurcation in the SD bands are analysed in the framework of the microscopic theory suggested by the author [Phys. Rev. C 55 (1997) 1275]. It is shown that the intruder orbitals are of paramount importance to the energy staggering.

Akihiko Yukie

In this note, we consider applications of Ratner&#39;s theorem to constructions of families of polynomials with dense values on the set of primitive integer points from the viewpoint of invariant theory.

A. Buonanno, K. Meissner, C. Ungarelli, G. Veneziano

Within two specific string cosmology scenarios --differing in the way the pre- and post-big bang phases are joined-- we compute the size and spectral slope of various types of cosmologically amplified quantum fluctuations that arise in generic compactifications of heterotic string theory. By further imposing that these perturbations become the dominant sourc

Krzysztof Gawedzki

The largely open problem of scaling laws in fully developed turbulence is discussed, with the stress put on similarities and differences with scaling in field theory. A soluble model of the passive advection is examined in more detail in order to illustrate the principal ideas.

Bertfried Fauser

Clifford geometric algebras of multivectors are treated in detail. These algebras are build over a graded space and exhibit a grading or multivector structure. The careful study of the endomorphisms of this space makes it clear, that opposite Clifford algebras have to be used also. Based on this mathematics, we give a fully Clifford algebraic account on gene

Sergei V. Ketov, Christine Unkmeir

Charged BPS hypermultiplets can develop a non-trivial self-interaction in the Coulomb branch of an N=2 supersymmetric gauge theory, whereas neutral BPS hypermultiplets in the Higgs branch may also have a non-trivial self-interaction in the presence of Fayet-Iliopoulos terms. The exact hypermultiplet low-energy effective action (LEEA) takes the form of the no

Yu. A. Sitenko, A. Yu. Babansky

The combined effect of the magnetic field background in the form of a singular vortex and the Dirichlet boundary condition at the location of the vortex on the vacuum of quantized scalar field is studied. We find the induced vacuum energy density and current to be periodic functions of the vortex flux and holomorphic functions of the space dimension.

B. J. Schroers

The dyonic quantum states of magnetic monopoles in Yang-Mills-Higgs theory with a non-abelian unbroken gauge group display a subtle interplay between magnetic and electric properties. This is described in detail in the theory with the gauge group SU(3) broken to U(2), and shown to be captured by the representation theory of the semi-direct product of U(2) wi

Marc Kamionkowski

There is almost universal agreement among cosmologists that most of the matter in the Universe is dark, and there are very good reasons to believe that most of this dark matter must be nonbaryonic. The two leading candidates for this dark matter are axions and weakly-interacting massive particles (WIMPs), such as the neutralino in supersymmetric extensions o

N. C. Tsamis, R. P. Woodard

We consider the effect of various particles on the cosmic expansion rate relative to that of the graviton. Effectively massless fermions, gauge bosons and conformally coupled scalars make only minuscule contributions due to local conformal invariance. Minimally coupled scalars can give much stronger contributions, but they are still sub-dominant to those of

P. Kroll, S. M. H. Wong

It is argued that colour octet contribution in exclusive charmonium decays is very important even though the same infrared divergence found in P-wave colour singlet inclusive decay is absent. This comes about because of the suppression at the level of the wavefunction of P-wave quarkonia. Using the modified hard scattering approach of Brodsky, Lepage, Botts,

Peter Levai, Ulrich Heinz

We analyze recent results of SU(3) lattice QCD calculations with a phenomenological parametrization for the quark-gluon plasma equation of state based on a quasi-particle picture with massive quarks and gluons. At high temperature we obtain a good fit to the lattice data using perturbative thermal quark and gluon masses from an improved HTL scheme. At temper

G. A. Schuler, F. A. Berends, R. van Gulik

Meson--photon--photon transition form factors for S-, P-, and D-wave states are calculated, the meson being treated as a non-relativistic heavy-quark--antiquark pair. The full dependence on both photon virtualities is included. Cross-section formulas for charge-conjugation even mesons with J^P = 0^-, 0^+, 1^+, 2^+, and 2^- in electron--positron collisions ar

D. Bruss, T. Gasenzer, O. Nachtmann

We consider hydrogen-like atoms in unstable levels of principal quantum number n=2, confined to a finite size region in a non-homogeneous electric field carrying handedness. The interplay between the internal degrees of freedom of the atoms and the external ones of their c.m. motion can produce P-odd contributions to the eigenenergies. The nominal order of s

G. Jikia

The processes of electroweak gauge boson production in high energy photon-photon collisions are surveyed.

Philip G. Ratcliffe

A new analysis of hyperon semi-leptonic decay data is presented, based on simple and general arguments for an SU(3)-breaking structure of the couplings involved. The results obtained are compatible with those of earlier investigations and highlight the uncertainties inherent in extraction of the V_us Cabibbo-Kobayashi-Maskawa matrix element from such data, a

M. Boglione, M. R. Pennington

The hadronic dressing of the ten lightest scalar mesons, the $q{\bar q}$ nonet and a glueball, is discussed.

M. R. Pennington

The relation between scattering and production amplitudes imposed by unitarity and analyticity, recently criticised by Ishida et al., is explained.

Robert Fleischer

The phenomenon of CP violation and strategies for extracting the angles of the unitarity triangle are reviewed. Special emphasis is given to the B-meson system, as it plays an outstanding role to test the Standard Model description of CP violation at future experimental B-physics facilities. Both general aspects and recent developments are discussed. It is p

Yoshiharu Kawamura, Tatsuo Kobayashi Jisuke Kubo

Assuming that the string inspired, universal sum rules for soft supersymmetry-breaking terms, which have been recently found both in a wide class of four-dimensional superstrings and in supersymmertic gauge-Yukawa unified gauge models, are satisfied above and at the grand unification scale, we investigate theirlow energy consequences and derive sum rules in

A. Ali Khan

The present status of lattice calculations of the B spectrum and f_B, using NRQCD for the b quark, is discussed.

Lakshmi Venkataraman, Gregory Kilcup

We have constructed the lowest few eigenvectors of the staggered Dirac operator on SU(3) gauge configurations, both quenched and dynamical. We use these modes to study the topological charge and to construct approximate hadronic correlators.

S. M. Caterall, M. Hasenbusch, R. R. Horgan, R. L. Renken

The 2D RP(2) gauge model is studied using the Monte-Carlo Renormalization Group. We confirm the first-order transition reported by Solomon et al. (PL 112B, (1982)) ending in a critical point associated with vorticity. We find evidence for a new renormalized trajectory which is responsible for a cross-over from the vortex dominated regime to the O(3) regime a

W. Bardeen, A. Duncan, E. Eichten, G. Hockney

In lattice QCD with Wilson fermions, exceptional configurations arise in the quenched approximation at small quark mass. The origin of these large previously uncontrolled lattice artifacts is identified. A simple well-defined procedure (MQA) is presented which removes the artifacts while preserving the correct continuum limit.

UKQCD Collaboration, T. Manke, I. T. Drummond, R. R. Horgan

We present a quenched lattice calculation for the lowest lying $b \bar b g$-hybrid states in the framework of NRQCD using the leading order Hamiltonian up to ${\cal O}(mv^2)$. We demonstrate the existence of a nearly degenerate rotational band of states with an excitation energy approximately 1.6 GeV above the $\Upsilon$ ground state. This lies around the $B

H. Fort

The recently proposed worldsheet formulation of lattice fermions is tested for the first time carrying out a simulation for the simplest model: the one-flavor, strictly massless lattice Schwinger model. A main advantage of this alternative method for simulating dynamical fermions consists in its economy: it involves many fewer degrees of freedom than the ord

J. M. Flynn

We review the results of lattice QCD calculations of form factors for semileptonic decays of D and B mesons. We also mention results for semileptonic decays of b baryons and the rare radiative decay B to K* gamma.

CLEO Collaboration, T. E. Coan et al

We have measured the branching fractions for B -> D_bar X, B -> D X, and B -> D_bar X \ell^+ ν, where ``B&#39;&#39; is an average over B^0 and B^+, ``D&#39;&#39; is a sum over D^0 and D^+, and``D_bar&#39;&#39; is a sum over D^0_bar and D^-. From these results and some previously measured branching fractions, we obtain Br(b -> c c_bar s) = (21.9 $\pm$ 3.7)%,

Daniel Cartin

This paper uses a generalization of symplectic geometry, known as $n$-symplectic geometry and developed by Norris, to find observables on three-dimensional manifolds. It will be seen that for the cases considered, the $n$-symplectic observables are derivable from the symplectic observables of $C^2$. The quantization of these observables, as well as those on

Tin-Lun Ho, V. B. Shenoy

The hydrodynamics equations of binary mixtures of Bose gases, Fermi gases, and mixtures of Bose and Fermi gases in the presence of external potentials are derived. These equations can be applied to current experiments on mixtures of atomic gases confined in magnetic traps.

Raffaella Burioni, Davide Cassi, Sofia Regina

Recently, we pointed out that on a class on non exactly decimable fractals two different parameters are required to describe diffusive and vibrational dynamics. This phenomenon we call dynamical dimension splitting is related to the lack of exact decimation invariance for these structures, which turn out to be invariant under a more complex cutting-decimatio

Andrea Cavagna, Irene Giardina, Giorgio Parisi

In the context of the p-spin spherical model, we introduce a method for the computation of the number of stationary points of any nature (minima, saddles, etc.) of the TAP free energy. In doing this we clarify the ambiguities related to the approximations usually adopted in the standard calculations of the number of states in mean field spin glass models.

Z. Y. Weng, D. N. Sheng, C. S. Ting

We propose a theory for doped antiferromagnet based on a bosonic resonating-valence-bond (RVB) state with incorporating the phase string effect. Both antiferromagnetic (AF) and superconducting phase transitions occur naturally within such a bosonic RVB phase. Two distinct metallic regions -- underdoping and optimum-doping -- are also found to be a logic cons

Rong Wang

By adopting the approximations suggested in the theory of thin shells, the hydrodynamic theory of liquid crystals established by Eriksen [Arch. Rational Mech. Anal. 4 (1960) 231; Trans. Soc. Rheol. 4 (1960) 29] and Leslie [Adv. Liq. Cryst. 4 (1979) 1] is modified so that it is applicable to study the lipid bilayer membranes.

Rong Wang

The exchange of mass, momentum and energy between a membrane of liquid crystal and its surroundings of stokesian fluids is added to the dynamic equations of membranes which were deduced from the Ericksen-Leslie&#39;s theory of liquid crystals [Rong Wang, Colloid. Sur. 112 (1996) 1].

M. A. Novotny, M. Kolesik, P. A. Rikvold

A model for single-domain uniaxial ferromagnetic particles with high anisotropy, the Ising model, is studied. Recent experimental observations have been made of the probability that the magnetization has not switched. Here an approach is described in which it is emphasized that a ferromagnetic particle in an unfavorable field is in fact a metastable system,

O. Jepsen, O. K. Andersen, I. Dasgupta, S. Savrasov

We have investigated whether the electron-phonon interaction can support a d-wave gap-anisotropy. On the basis of models derived from LDA calculations, as well as LDA linear-response calculations we argue that this is the case, for materials with buckled or dimpled CuO2 planes, for the so-called buckling modes, which involve out-of-plane movements of the pla

J. Cserti, G. Szálka, G. Vattay

In this paper we will give a short rewiew about the conductance of a mesoscopic waveguide strip with a few impurities. Green-function method is used allowing to treat systems with low number of impurities, not only the completly clean case. Investigating a wire containing Dirac-delta potentials (modelling the impurities) we found that increasing number of im

J. Cserti, G. Szálka, G. Vattay

The conductance of a waveguide containing finite number of periodically placed identical point-like impurities is investigated. It has been calculated as a function of both the impurity strength and the number of impurities using the Landauer-Büttiker formula. In the case of few impurities the conductance is proportional to the number of the open channels $N

Yu-Liang Liu

Using the bosonization method, we study the low temperature behavior of the Kondo effect in the Tomonaga-Luttinger liquid and clearly show that the power law temperature dependence of the impurity susceptibility is completely determined by the repulsive electron-electron interaction existing in the total spin channel and is independent of the electron-electr

Bang-Gui Liu, Gerd Czycholl

An infinity magnon coupling term is introduced into the Holstein-Primakoff transformed forms of the Heisenberg ferromagnetic and antiferromagnetic models of any spin $s$ to rigorously remove the unphysical magnon states. This term makes the series expansion of the square root of the magnon operators become a finite series of magnon operator products. Under a

Massimo Poesio, Renata Vieira

We present the results of a study of definite descriptions use in written texts aimed at assessing the feasibility of annotating corpora with information about definite description interpretation. We ran two experiments, in which subjects were asked to classify the uses of definite descriptions in a corpus of 33 newspaper articles, containing a total of 1412

Kevin P. Rauch, Brian Ingalls

It has recently been shown that the rate of angular momentum relaxation in nearly-Keplerian star clusters is greatly increased by a process termed resonant relaxation (Rauch & Tremaine 1996), who also argued that tidal disruption of stars in galactic nuclei containing massive black holes could be noticeably enhanced by this process. We describe here the resu

V. R. Chitnis, A. R. Rao, P. C. Agrawal

We present the hard X-ray (20-100 keV) observations of Cygnus X-1 obtained using a large area balloon-borne Xenon filled Multi-anode Proportional Counter (XMPC) telescope. The observations were carried out during the gamma_2 state of the source and we obtain a power law photon index of 1.62 +- 0.07. To constrain the spectral shape of the source, we have anal

B. Paul, P. C. Agrawal, A. R. Rao

Three different types of very intense, quasi-regular X-ray bursts have been observed from the Galactic superluminal X-ray transient source GRS 1915+105 with the Pointed Proportional Counters of the Indian X-ray Astronomy Experiment onboard the Indian satellite IRS-P3. The observations were carried out from 1997 June 12 to June 29 in the energy range of 2-18

A. R. Rao, P. C. Agrawal, B. Paul

We present the time variability characteristics of Cygnus X-1 in its two spectral states. The observations were carried out using the Pointed Proportional Counters (PPC) on-board the Indian X-ray Astronomy Experiment (IXAE). The details of the instrument characteristics, the observation strategy, and the background modeling methods are described. In the soft

B. Paul, P. C. Agrawal, A. R. Rao

The galactic superluminal transient X-ray source GRS 1915+105 was observed with the pointed proportional counters (PPCs) onboard the Indian satellite IRS-P3 during 1996 July 23-27. We report here details of the behavior of this source during the relatively quiet and low luminosity state. Large intensity variations by a factor of 2 to 3, generally seen in bla

Guy S. Miller, Myeong-Gu Park

In this paper we examine time-dependent and three-dimensional perturbations of spherical accretion flow onto a neutron star close to its Eddington limit. Our treatment assumes a Schwarzschild geometry for the spacetime outside the neutron star and is fully general relativistic. At all the accretion rates studied, the response of the accretion flow to perturb

Peter R. Newman, Roger G. Clowes, Luis E. Campusano, Matthew J. Graham

The Chile-UK quasar survey, a new-generation 140 deg^2 UVX survey to B = 20, is now \sim 25 per cent complete. The catalogue currently contains 319 quasars and 93 emission line galaxies. Using the minimal-spanning tree method, we have independently confirmed the \sim 200 h^-1 Mpc group of quasars at z \simeq 1.3 discovered by Clowes & Campusano (1991). We ha

D. M. Sedrakian, A. Sedrakian, G. F. Zharkov

The magnetic structure of neutron vortices in the superfluid cores of neutron stars is determined assuming that the proton condensate forms a type I superconductor. It is shown that the entrainment currents induced by the neutron vortex circulation cause the proton superconductor to break into successive domains of normal and superconducting regions. The Gib

E. B. Jenkins, T. M. Tripp, E. L. Fitzpatrick, D. Lindler

The star HD72089 is located behind the Vela supernova remnant and shows a complex array of high and low velocity interstellar absorption features arising from shocked clouds. A spectrum of this star was recorded over the wavelength range 1196.4 to 1397.2 Angstroms at a resolving power lambda/Delta lambda = 110,000 and signal-to-noise ratio of 32 by STIS on t

M. Wahde

A method for determining the orbital parameters of interacting pairs of galaxies is presented and evaluated using artificial data. The method consists of a genetic algorithm which can search efficiently through the very large space of possible orbits. It is found that, in most cases, orbital parameters close to the actual orbital parameters of the pair can b

J. Knapp

In this report a summary of recent developments in the fields of high-energy nuclear interactions (HE 1) and air shower phenomenology (HE 2) is presented. New results from accelerator and cosmic-ray experiments and the progress in the theoretical understanding and simulation are reviewed and their impact on air shower analysis is discussed.

D. Barrado y Navascues, A. K. Dupree

The observation of the Ca II H and K lines in red giants in NGC 6940 allows the strength of chromospheres and their behavior to be evaluated in a population whose evolution is well understood. Spectra in the Ca II lines have been obtained for giant stars in this cluster. Emission reversals are present in some objects. The absolute flux in the chromospheric e

D. Barrado y Navascues, J. R. Stauffer, S. Balachandran

A study of the lithium abundances in binaries of the old open cluster M67 is presented. Abundances were estimated using curves of growth and equivalent widths of the LiI6707.8 Å doublet. We have corrected of the effects of the companion on the measured equivalent width and on the color indices by deconvolving the photometry, computing colors and magnitudes f

David Barrado y Navascues

We present an analysis of the lithium abundances in late spectral type binaries of different ages. They belong to several open clusters (Pleiades, Hyades and M67), as well as to Chromospherically Active Binary Systems (CABS). All these binaries have reliable ages, since they are members of well-known open clusters or, in the case of the CABS, some stellar pa