November 1996 arXiv papers — page 12

M. Woods, representing the SLD collaboration

For the 1994/95 run of the SLD experiment at SLAC, a Compton polarimeter measured the luminosity-weighted electron beam polarization to be (77.2 +- 0.5)%. This excellent accuracy is achieved by measuring the rate asymmetry of Compton-scattered electrons near the kinematic endpoint. The polarimeter takes data continuously while the electron and positron beams

Alberto Saa

It is considered, in the framework of constrained systems, the quantum dynamics of non-relativistic particles moving on a d-dimensional Riemannian manifold M isometrically embedded in $R^{d+n}$. This generalizes recent investigations where M has been assumed to be a hypersurface of $R^{d+1}$. We show, contrary to recent claims, that constrained systems theor

K. -H. Rehren

Various generalizations of Cuntz algebras and their relations to symmetry and duality are reviewed. New generalized Cuntz algebras are associated with a subfactor. A characteristic Hilbert space of basic invariants (with respect to the generalized symmetry) within these algebras is discussed.

Z. J. Liu, A. Weinstein, P. Xu

Poisson homogeneous spaces for Poisson groupoids are classfied in terms of Dirac structures for the corresponding Lie bialgebroids. Applications include Drinfel'd's classification in the case of Poisson groups and a description of leaf spaces of foliations as homogeneous spaces of pair groupoids.

Andrea Cavagna, Irene Giardina, Giorgio Parisi

We introduce a three replica potential useful to examine the structure of metastables states above the static transition temperature, in the spherical p-spin model. Studying the minima of the potential we are able to find which is the distance between the nearest equilibrium and local equilibrium states, obtaining in this way information on the dynamics of t

Gu Yan, T. C. Lubensky

We introduce a model to describe columnar phases of chiral discotic liquid phases in which the normals to disc-like molecules are constrained to lie parallel to columnar axes. The model includes separate chiral interactions favoring, respectively, relative twist of chiral molecules along the axes of the columns and twist of the two-dimensional columnar latti

T. Veitshans, D. K. Klimov, D. Thirumalai

The folding kinetics of a number of sequences for off-lattice continuum model of proteins is studied using Langevin simulations at two values of the friction coefficient. We show that there is a remarkable correlation between folding times, $τ_{F}$, and $σ= (T_{θ} - T_{F})/T_{θ} $, where $T_{θ}$ and $T_{F}$ are the equilibrium collapse and folding transition

H. Aubin, K. Behnia, M. Ribault, R. Gagnon

The thermal conductivity of a YBCO single crystal has been studied as a function of the relative orientation of the crystal axes and a magnetic field rotating in the Cu-O planes. Measurements were carried out at several temperatures below T_c and at a fixed field of 30 kOe. A four-fold symmetry characteristic of a superconducting gap with nodes at odd multip

Igor V. Beloussov, Vladimir V. Frolov

Time evolution of a nonequilibrium polariton condensate has been studied in the framework of a microscopic approach. It has been shown that due to polariton-polariton scattering a significant condensate depletion takes place in a comparatively short time interval. The condensate decay occurs in the form of multiple echo signals. Distribution-function dynamic

T. Haugset, H. Haugerud, J. O. Andersen

We study the thermodynamic behaviour of an ideal gas of bosons trapped in a three-dimensional anisotropic harmonic oscillator potential. The condensate fraction as well as the specific heat is calculated using the Euler-Maclaurin approximation. For a finite number of particles there is no phase transition, but there is a well defined temperature at which the

D. Braun, E. Hofstetter, G. Montambaux, A. MacKinnon

The Thouless conjecture states that the average conductance of a disordered metallic sample in the diffusive regime can be related to the sensitivity of the sample's spectrum to a change in the boundary conditions. Here we present results of a direct numerical study of the conjecture for the Anderson model. They were obtained by calculating the Landauer-

G. Juttner, A. Klumper, J. Suzuki

A Trotter-Suzuki mapping is used to calculate the finite-temperature properties of the one-dimensional supersymmetric $t-J$ model. This approach allows for the exact calculation of various thermodynamical properties by means of the quantum transfer matrix (QTM). The free energy and other interesting quantities are obtained such as the specific heat and compr

Masanori Yamanaka, Mahito Kohmoto

We investigate the effects of randomness in a strongly correlated electron model in one-dimension at half-filling. The ground state correlation functions are exactly written by products of 3$\times$3 transfer matrices and are evaluated numerically. The correlation lengths depend on randomness when the interaction is effectively weak. On the contrary, they ar

Neil Trentham

We measure luminosity functions in the cores of four spiral-rich, poor clusters of galaxies at median redshift $z = 0.016$. In the red magnitude range -14 < M_R < -10, our data imply that the luminosity functions phi(L) \propto L^{alpha} are steep, -1.8 < alpha < -1.6, in the central 200-300 kpc of Abell 262 and of the NGC 507 Group. Abell 194 also shows sig

Daniel Schaerer, Alex de Koter

We provide an extensive set of theoretical spectral energy distributions of massive stars derived from our &#34;combined stellar structure and atmosphere models&#34;. The calculations covering the entire main sequence evolution for initial masses M_i=20 - 120 Msun (O3-B0 stars of all luminosity classes) are used for a systematic study of the ionizing fluxes

Grazyna Stasinska, Daniel Schaerer

We study the impact of modern stellar atmospheres that take into account the effects of stellar winds, departures from LTE and line blanketing (&#34;CoStar&#34; models) on the ionization structure of HII regions. Results from a large grid of photoionization models are presented. Due to a flatter energy distribution in the HeI continuum, compared to the widel

R. Buonanno, C. Corsi, M. Bellazzini, F. R. Ferraro

The Horizontal Branch (HB) morphology in the color -- magnitude diagram of the Galactic globular clusters depends on many factors, and it is now firmly established that the so-called Second Parameter is not just the cluster age as claimed for several years. As a part of a wider program devoted to the search for the physical processes driving the Horizontal B

Paul Goudfrooij

Results from IRAS and recent X-ray and optical surveys are reviewed to discuss the properties and nature of the interstellar medium in elliptical galaxies. As to the dust component, there is a strong contrast with the situation among spiral galaxies in that masses of dust in ellipticals as derived from optical extinction are an order of magnitude LOWER than

Serkan Hosten

In this paper we answer a question posed by V.V. Batyrev. The question asked if there exists a complete regular fan with more than quadratically many primitive collections. We construct a smooth projective toric variety associated to a complete regular fan $Δ$ in R^d with $n$ generators where the number of primitive collections of $Δ$ is at least exponential

Aleksandr V. Pukhlikov

It is proved that on a smooth algebraic variety, fibered into cubic surfaces over the projective line and sufficiently ``twisted&#39;&#39; over the base, there is only one pencil of rational surfaces -- that is, this very pencil of cubics. In particular, this variety is non-rational; moreover, it can not be fibered into rational curves. The proof is obtained

Alexander Schmitt

We give an algebraic geometric compactification of certain moduli spaces of semistable E-pairs in the sense of Yokogawa. In particular, we obtain a compactification of the moduli spaces of semistable Higgs pairs on a curve which were constructed by N. Hitchin.

J. G. Russo, A. A. Tseytlin

Certain type II string non-threshold BPS bound states are shown to be related to non-static backgrounds in 11-dimensional theory. The 11-d counterpart of the bound state of NS-NS and R-R type IIB strings wound around a circle is a pure gravitational wave propagating along a generic cycle of 2-torus. The extremal (q_1,q_2) string with non-vanishing momentum a

HongGuang Bi, Arthur F. Davidsen

We have performed a detailed statistical study of the evolution of structure in a photoionized intergalactic medium (IGM) using analytical simulations to extend the calculation into the mildly non-linear density regime found to prevail at z = 3. Our work is based on a simple fundamental conjecture: that the probability distribution function of the density of

H Umeda

withdrawn for revision

Michael Krämer, Eric Laenen, Michael Spira

We examine the contributions of soft gluons to the Higgs production cross section at the LHC in the Standard Model and its minimal supersymmetric extension. The soft gluon radiation effects of this reaction share many features with the Drell-Yan process, but arise at lowest order from a purely gluonic initial state. We provide an extension of the conventiona

W. A. Hofer

The wave-structure of moving electrons is analyzed on a fundamental level by employing a modified de Broglie relation. Formalizing the wave-function $ψ$ in real notation yields internal energy components due to mass oscillations. The wave-features can then be referred to physical waves of discrete frequency $ν$ and the classical dispersion relation $λν= u $,

B. Holdom

From a simple path integral involving a variable volatility in the velocity differences, we obtain velocity probability density functions with exponential tails, resembling those observed in fully developed turbulence. The model yields realistic scaling exponents and structure functions satisfying extended self-similarity. But there is an additional small sc

M. A. Halasz, A. D. Jackson, J. J. M. Verbaarschot

We study the Yang-Lee zeros of a random matrix partition function with the global symmetries of the QCD partition function. We consider both zeros in the complex chemical potential plane and in the complex mass plane. In both cases we find that the zeros are located on a curve. In the thermodynamic limit, the zeros appear to merge to form a cut. The shape of

A. Akhundov, S. Bellucci, A. Shiekh

We carry out the first step of a program conceived, in order to build a realistic model, having the particle spectrum of the standard model and renormalized masses, interaction terms and couplings, etc. which include the class of quantum gravity corrections, obtained by handling gravity as an effective theory. This provides an adequate picture at low energie

K. -H. Rehren

Weak C* Hopf algebras can act as global symmetries in low-dimensional quantum field theories, when braid group statistics prevents group symmetries. Possibilities to construct field algebras with weak C* Hopf symmetry from a given theory of local observables are discussed.

Makoto Natsuume, Yuji Satoh

We investigate the string theory on three dimensional black holes discovered by Bañados, Teitelboim and Zanelli in the framework of conformal field theory. The model is described by an orbifold of the $\widetilde{SL}(2,R)$ WZW model. The spectrum is analyzed by solving the level matching condition and we obtain winding modes. We then study the ghost problem

Shinji Mukohyama

The generalized second law of black hole thermodynamics was proved by Frolov and Page for a quasi-stationary eternal black hole. However, realistic black holes arise from a gravitational collapse, and in this case their proof does not hold. In this paper we prove the generalized second law for a quasi-stationary black hole which arises from a gravitational c

N. Uraltsev

I give a brief outline of the theoretical framework for the modern treatment of the strong interaction effects in heavy quark decays, based on first principles of QCD. This model-independent approach is required to meet the precision of current and future experiments. Applications to a few problems of particular practical interest are reviewed, including the

Rupert A. C. Croft, David H. Weinberg, Neal Katz, Lars Hernquist

Observations from the HUT and the HST have recently detected HeII absorption along the lines of sight to two high redshift quasars. We use cosmological simulations with gas dynamics to investigate HeII absorption in the cold dark matter (CDM) theory of structure formation. We consider two Omega=1 CDM models with different normalizations and one Omega_0=0.4 C

Achilles D. Speliotopoulos

Hilbert Spaces of bounded one dimensional non-linear oscillators are studied. It is shown that the eigenvalue structure of all such oscillators have the same general form. They are dependent only on the ground state energy of the system and a single functional $λ(H)$ of the Hamiltonian $H$ whose form depends explicitly on $H$. It is also found that the Hilbe

Jan de Gier, Bernard Nienhuis

It is shown that the square-triangle random tiling model is equivalent to an asymmetric limit of the three colouring model on the honeycomb lattice. The latter model is known to be the O(n) model at T=0 and corresponds to the integrable model connected to the affine $A_2^{(1)}$ Lie algebra. Thus it is shown that the weights of the square-triangle random tili

Christopher A. Fuchs

The engine that powers quantum cryptography is the principle that there are no physical means for gathering information about the identity of a quantum system&#39;s state (when it is known to be prepared in one of a set of nonorthogonal states) without disturbing the system in a statistically detectable way. This situation is often mistakenly described as a

Alexander Kirillov

This is the second part of the paper (the first part is published in Jour. of AMS, vol.9, 1135--1170, q-alg/9508017). In the first part, we defined for every modular tensor category (MTC) inner products on the spaces of morphisms and proved that the inner product on the space $\Hom (\bigoplus X_i\otimes X^*_i, U)$ is modular invariant. Also, we have shown th

R. Cenni, F. Conte, P. Saracco

The separated electromagnetic responses $R_L(q,ω)$ and $R_T(q,ω)$ for inclusive electron scattering off nuclei are studied within a functional scheme.

C. David, C. Hartnack, M. Kerveno, J. -Ch. Le Pallec

Applying a new method of rescattering which is based on the neural network technique we study the influence of rescattering on the spectra of strange particles produced in heavy ion reactions. In contradistinction to former approaches the rescattering is done explicitly and not in a perturbative fashion. We present a comparison of our calculations for the sy

R. Bijker, A. Frank, S. Pittel

A recent analysis of experimental energy systematics suggests that all collective nuclei fall into one of three classes -- seniority, anharmonic vibrational, or rotational -- with sharp phase transitions between them. We investigate the transition from the seniority to the anharmonic vibrator regime within a shell model framework involving a single large j-o

P. Magierski, K. Burzynski, E. Perlinska, J. Dobaczewski

The influence of quadrupole and hexadecapole residual interactions on rotational bands is investigated in a single-j shell model. An exact shell-model diagonalization of quadrupole-plus-hexadecapole interaction can sometimes produce a staggering of energy levels in the yrast bands.

R. Shyam, U. Mosel

We calculate the cross sections for the $p(p,nπ^{+})p$ and $p(p,pπ^{0})p$ reactions for proton beam energies near threshold in a covariant one-boson-exchange model, which incorporates the exchange of $π$, $ρ$, $σ$ and $ω$ mesons and treats both nucleon and delta isobar as intermediate states. The final state interaction effects have also been included. The $

G. Hjorth

This paper considers &#34;definable cardinalities&#34; arising from Polish group actions. The first part of the paper answers a question of Becker-Kechris by showing that under suitable determinacy assumptions in ZF+DC, every action by a Polish group on a metric space is either as complicated as the Vitali equivalence relation or no more complicated than the

Michael Eastwood, C. Robin Graham

We investigate the natural involutive structure on the blow-up of ${\Bbb R}^n$ in ${\Bbb C}^n$ extending the complex structure on the complement of the exceptional hypersurface. Our main result is that this structure is hypocomplex, meaning that any solution is locally a holomorphic function of a basic set of independent solutions. We show this by an element

Gerald Dunne, Theodore Hall

An algebraic restriction of the nonabelian self-dual Chern-Simons-Higgs systems leads to coupled-abelian self-dual models with intricate mass spectra. The vacua are characterized by embeddings of SU(2) into the gauge algebra; and in the broken phases, the gauge and real scalar masses are related to the exponents of the gauge algebra. In this paper we compute

Michael G. Schmidt, Christian Schubert

We explain the concept of worldline Green functions on classes of multiloop graphs. The QED beta function and the 2-loop Euler-Heisenberg Lagrangian are discussed for illustration.

Michael G. Schmidt, Christian Schubert

In the framework of the worldline path integral approach to QFTH we discuss spin and relativistic couplings, in particular Yukawa and axial couplings to spin 1/2, and the case of spin 1 in the loop.

Peter van Nieuwenhuizen, Andrew Waldron

We obtain a continuous Wick rotation for Dirac, Majorana and Weyl spinors $ψ\to \exp ({1\over 2} θγ^4 γ^5)ψ$ which interpolates between Minkowski and Euclidean field theories.

Washington Taylor

We consider Dirichlet p-branes in type II string theory on a space which has been toroidally compactified in d dimensions. We give an explicit construction of the field theory description of this system by putting a countably infinite number of copies of each brane on the noncompact covering space, and modding out the resulting gauge theory by Z^d. The resul

F. Lizzi, N. E. Mavromatos

In this paper we view the sigma-model couplings of appropriate vertex operators describing the interaction of string matter with a certain type of string solitons (0-branes) as the quantum phase space of a point particle. The sigma-model is slightly non critical, and therefore one should dress it with a Liouville mode. Quantization is achieved by summing ove

R. N. Mohapatra, A. Riotto

We construct realistic supergravity models where supersymmetry breaking arises from the D-terms of an anomalous U(1) gauge symmetry broken at the Planck scale. Effective action for these theories at sub-Planck energies (including higher dimensional terms in the superpotential) are severely restricted by the U(1) symmetry and by the assumption that they arise

Alfio Bonanno, Dario Zappalá

A renormalization group study of a scalar theory coupled to gravity through a general functional dependence on the Ricci scalar in the action is discussed. A set of non-perturbative flow equations governing the evolution of the new interaction terms generated in both local potential and wavefunction renomalization is derived. It is shown for a specific model

V. R. Zoller

We study coherent enhancement of Coulomb excitation of high energy particles in crystals. We develop multiple scattering theory description of coherent excitation which consistently incorporates both the specific resonant properties of particle-crystal interactions and the final/initial state interaction effects typical of the diffractive scattering. Possibl

G. Calucci, R. Ragazzon, D. Treleani

Multiparton interactions modify the high energy hadronic cross section to produce minijets with a rapidity gap in the distribution of secondaries. At Tevatron energy the correction to the single scattering term is large for transverse momenta smaller than 6 GeV.

L. Lavoura

I put forward a model with vectorlike isosinglet quarks in which soft breaking of CP leads to strong CP violation only arising at two-loop level.

Eric Braaten

Sufficiently inclusive observables in the decay of the tau lepton can be calculated using the methods of perturbative QCD. These include the asymmetry parameter $A_τ$ that determines that angular distribution of the total hadron momentum in the decay of a polarized tau. It should be possible to measure $A_τ$ accurately using existing data from LEP. Reliable

L. Lavoura

I put forward an SU(2)_L x SU(2)_R x U(1) model in which spontaneously broken parity symmetry makes it that strong CP violation only arises at three-loop level. All leptons and up-type quarks are in doublets either of SU(2)_L or of SU(2)_R, but there are singlet down-type quarks. A bi-doublet of scalars is introduced which has only one component with non-van

Gustavo Burdman

We review the motivation and main aspects of Topcolor models with emphasis on the spectrum of relatively light scalars and pseudo-scalars.

Miguel A. Sanchis-Lozano, Beatriz Cano-Coloma

We firstly examine hadroproduction of prompt J/psi&#39;s at the Fermilab Tevatron in a Monte Carlo Framework by means of the event generator PYTHIA 5.7 in which those colour-octet matrix elements processes relevant for charmonium production have been implemented accordingly. We find that colour-octet matrix elements presented in literature from p-pbar collid

Hooman Davoudiasl

Boost-invariant (1+1) dimensional solutions for the Disoriented Chiral Condensate (DCC) are obtained numerically, in the context of the $SU(2)_L \otimes SU(2)_R$ non-linear sigma model at O(p^4) in the momentum expansion. We ignore the mass terms in the Lagrangian, as we are mainly interested in the behavior of the solutions for small values of proper time $

S. Kumano

We give a brief summary of the Gottfried sum rule and a flavor asymmetric distribution $\bar u-\bar d$ in the nucleon. First, experimental history of the sum-rule studies is discussed. Second, future prospects for studying the asymmetry at Fermilab and RHIC are discussed. We also comment on possible nuclear modification.

B. Machet

After developing in ref.[1] a SU(2)left x U(1) gauge theory for J=0 mesons, I show in the case of two generations that: - the electroweak mass eigenstates differ, especially in the K and D sector, from what they are assumed to be on the basis of a classification by the SU(4) group of flavour; - a new mechanism for CP violation springs out, different from tha

J. W. Bos, D. Chang, S. C. Lee, Y. C. Lin

We examine the constraints imposed by reparametrization invariance on heavy-baryon chiral perturbation theory (HBChPT). We study the case of 3 flavors and consider both the strong and weak ($|ΔS| =1$) interaction sector. Some of the parameters in the HBChPT Lagrangian are fixed as a consequence of reparametrization invariance. We discuss the consequences for

He-Ping Ying, Shao-Jing Dong, Keh-Fei Liu

We test iterative algorithms, MR, QMR$γ_5$ and BiCG$γ_5$, to compare their efficiency in matrix inversion with multi-quarks (shifted matrices) within one iteration process. Our results on the 8^3 x 12 and 16^3 x 24 show that MR admits multi-quark calculation with less memory requirement, whereas QMR is faster for the single quark calculation.

Julien Lesgourgues, David Polarski, Alexei A. Starobinsky

Transition from quantum to semiclassical behaviour and loss of quantum coherence for inhomogeneous perturbations generated from a non-vacuum initial state in the early Universe is considered in the Heisenberg and the Schrödinger representations, as well as using the Wigner function. We show explicitly that these three approaches lead to the same prediction i

Francesco Mauri, Bernd G. Pfrommer, Steven G. Louie

We present a theory for the ab-initio computation of NMR chemical shifts (sigma) in condensed matter systems, using periodic boundary conditions. Our approach can be applied to periodic systems such as crystals, surfaces, or polymers and, with a super-cell technique, to non-periodic systems such as amorphous materials, liquids, or solids with defects. We hav

Howard L. Richards, M. Kolesik, Per-Anker Lindgard, Per Arne Rikvold

Magnetization switching in highly anisotropic single-domain ferromagnets has been previously shown to be qualitatively described by the droplet theory of metastable decay and simulations of two-dimensional kinetic Ising systems with periodic boundary conditions. In this article we consider the effects of boundary conditions on the switching phenomena. A rich

M. Fischer, P. Lemmens, G. Güntherodt, M. Weiden

Using Raman scattering we studied the effect of substitutions on 1D spin fluctuations in CuGeO_3 observed as a spinon continuum in frustration induced exchange scattering. For temperatures below the spin-Peierls transition (T_{SP}=14K) the intensity of this continuum at 120-500 cm^{-1} is exponentially suppressed and transferred into a 3D two-magnon density

J. A. Melsen, Ulrik Hanke, H. -O. Müller, K. -A. Chao

A general expression is given for the change in free energy when a charge tunnels through a junction in a one-dimensional array of N metallic islands with arbitrary capacitances and arbitrary background charges. This is used to obtain expressions for the (average) threshold voltage of the Coulomb blockade for a few characteristic geometries. We find that inc

Leticia F. Cugliandolo, Jorge Kurchan

The low-temperature generalization of the mode-coupling equations corresponds to the dynamics of mean-field disordered models in the glassy phase. The system never achieves equilibrium, preserving the memory of the time elapsed after the quench throughout its evolution. A concept of effective temperature can be made quite rigorous in this context by consider

Ekkehard Lange

The anomalous frequency and doping dependence of the Hall constant in the normal state of high-T_c superconductors are investigated within models of strongly correlated electron systems. In Mori theory, the transition of the Hall constant from infinite to zero frequency is described by a memory function. It naturally introduces a second time scale, that, wit

Alex Lazarian, Dmitri Pogosyan

This paper presents a statistical explanation of filament formation in the galactic atomic hydrogen. Recently developed technique allows to determine the 3D spectrum of random HI density. We claim that even in the absence of dynamical factors the Gaussian field corresponding to the measured values of the spectrum of HI density should exhibit filamentary stru

Anatoly Miroshnichenko, Zeljko Ivezic, Moshe Elitzur

The spectral shape of IR emission from Herbig Ae/Be stars has been invoked as evidence for accretion disks around high-mass protostars. Instead, we present here models based on spherical envelopes with $r^{-1.5}$ dust density profile that successfully explain the observed spectral shapes. The spectral energy distributions (SEDs) of eight primary candidates f

S. E. Levine

Elliptical galaxies have been observed to cluster near a ribbon along a two-dimensional plane (the Fundamental Plane of Elliptical Galaxies) in the three dimensional space of effective radius, effective surface brightness and central velocity dispersion. This observed clustering holds for galaxies spanning several orders of magnitude in size and total bright

The MACHO Collaboration, W. Sutherland, C. Alcock, R. A. Allsman

The MACHO project is searching for dark matter in the form of massive compact halo objects (Machos), by monitoring the brightness of millions of stars in the Magellanic Clouds to search for gravitational microlensing events. Analysis of our first 2.3 years of data for 8.5 million stars in the LMC yields 8 candidate microlensing events, well in excess of the

Mark J. McCaughrean, Mordecai-Mark Mac Low

We present new images of the OMC-1 molecular hydrogen outflow, made using long-slit spectroscopy in order to accurately subtract the underlying continuum emission. These images reveal an extremely clumpy, quasi-spherical inner shell that breaks up at larger radii into bow-shocks and trailing wakes in the north-west, as originally described by Allen & Burton

Andrew Gould

During some gravitational lensing events, the lens transits the face of the star. This causes a shift in the apparent radial velocity of the star which is proportional to its rotation speed. It also changes the magnification relative to what would be expected for a point source. By measuring both effects, one can determine the rotation parameter $v\sin i$. T

M. Ruffert, M. Rampp, H. -Th. Janka

The dynamics, time evolution of the mass distribution, and gravitational wave signature of coalescing neutron stars described by polytropes are compared with three simulations published previously: (a) ``Run 2&#39;&#39; of Zhuge et al. (1994), (b) ``Model III&#39;&#39; of Shibata et al. (1992), and (c) ``Model A64&#39;&#39; of Ruffert et al. (1996). We aim a

V. P. Reshetnikov

We discuss the properties of two peculiar galaxies (2-809 and 2-906) selected in the Hubble Deep Field as possible candidates to high-redshift (Z about 1) polar-ring galaxies. We found that the presence of polar-ring galaxies in a random deep field gives some support for a galaxy interaction rate steeply increasing with redshift.

M. H. van Kerkwijk

I introduce the two classes of pulsar, white-dwarf binaries, and describe for each what we have learned from a specific system, PSR J1012+5307 and PSR B0655+64, respectively, summarising what has been done, presenting new results, and discussing what the future may hold. Briefly, for the companion of PSR J1012+5307 we find a DA spectrum, and infer a mass of

A. Langari, V. Karimipour

A simple modification of the standard Renormalization Group (RG) technique for the study of quantum spin systems is introduced. Our method which takes into account the effect of boundary conditions by employing the concept of superblock, may be regarded as a simple way for obtaining first estimates of many properties of spin systems. By applying this method

Dong-Shin Shin

We calculate the finite volume mass gap $M(L)$ at 3-loop level in the non-linear O($n$) $σ$-model in two dimensions in small volumes. By applying the Monte Carlo measurements of the running coupling $\bar g^2(L)=2nM(L)L/(n-1)$ by Lüscher, Weisz and Wolff measured in units of the physical mass gap $m$, the result is used to determine $m$ in units of the $Λ$-p

M. Gasperini, M. Maggiore, G. Veneziano

We discuss general features of the $\beta$-function equations for spatially flat, $(d+1)$-dimensional cosmological backgrounds at lowest order in the string-loop expansion, but to all orders in $\alpha'$. In the special case of constant curvature and a linear dilaton these equations reduce to $(d+1)$ algebraic equations in $(d+1)$ unknowns, whose solutions c

Harry Tamvakis

Let \E : 0 --> S --> E --> Q --> 0 be a short exact sequence of hermitian vector bundles with metrics on S and Q induced from that on E. We compute the Bott-Chern form of \E corresponding to any characteristic class, assuming E is projectively flat. The result is used to obtain a new presentation of the Arakelov Chow ring of the arithmetic grassmannian.

Marco D&#39;Attanasio, Massimo Pietroni

We propose a gauge-invariant version of Wilson Renormalization Group for thermal field theories in real time. The application to the computation of the thermal masses of the gauge bosons in an SU(N) Yang-Mills theory is discussed.

G. K. Leontaris, N. D. Tracas

The Higgs mixing term coefficient $μ_{eff}$ is calculated in the scalar potential in supergravity theories with string origin, in a model independent approach. A general low energy effective expression is derived, where new contributions are included which depend on the modular weights $q_{1,2}$ of the Higgs superfields, the moduli and derivative terms. We f

Erick J. Guerra, Ruth A. Daly

Powerful extended radio galaxies in the 3CR survey are observed out to redshifts of about 2. For redshifts greater than about 0.3, the average lobe-lobe size of the sources decreases monotonically with redshift for all reasonable cosmological parameter choices. This suggests that the characteristic time for which an AGN produces a highly collimated outflow t

D. A. Head, G. J. Rodgers

We describe a simple model of evolution which incorporates the branching and extinction of species lines, and also includes abiotic influences. A first principles approach is taken in which the probability for speciation and extinction are defined purely in terms of the fitness landscapes of each species. Numerical simulations show that the total diversity f

Sergiu I. Vacaru

The work proposes a geometric background of the theory of field interactions and strings in spaces with higher order anisotropy. Our approach proceeds by developing the concept of higher order anisotropic superspace which unifies the logical and mathematical aspects of modern Kaluza-Klein theories and generalized Lagrange and Finsler geometry and leads to mo

V. Bernard, N. Kaiser, Ulf-G. Meißner

The next-to-leading order chiral pion-nucleon Lagrangian contains seven finite low-energy constants. Two can be fixed from the nucleon anomalous magnetic moments and another one from the quark mass contribution to the neutron-proton mass splitting. We find a set of nine observables, which to one loop order do only depend on the remaining four dimension two c

Jose I. Burgos, Steve Wang

Let X be a smooth complex algebraic variety. In this paper, we associate, to each exact n-cube of hermitian vector bundles over X, a differential form, called higher Bott Chern form, which generalizes the Bott Chern forms associated to an exact sequence of hermitian vector bundles. With these forms we construct characteristic classes for higher K-theory and

F. Delduc, L. Gallot, E. Ivanov

We present a new integrable extension of the a=-2, N=2 SKdV hierarchy, with the &#34;small&#34; N=4 superconformal algebra (SCA) as the second hamiltonian structure. As distinct from the previously known N=4 supersymmetric KdV hierarchy associated with the same N=4 SCA, the new system respects only N=2 rigid supersymmetry. We give for it both matrix and scal

D. F. Wang

In this work, the spinless Calogero-Sutherland model with twisted boundary condition is studied. The ground state wavefunctions, the ground state energies, the full energy spectrum are provided in details.

James Anglin

We present a master equation governing the reduced density operator for a single trapped mode of a cold, dilute, weakly interacting Bose gas; and we obtain an operator fluctuation-dissipation relation in which the Ginzburg-Landau effective potential plays a physically transparent role. We also identify a decoherence effect that tends to preserve symmetry, ev

Kentaro Imafuku, Ichiro Ohba, Yoshiya Yamanaka

We analyze the effects of inelastic scattering on the tunneling time theoretically, using generalized Nelson&#39;s quantum mechanics. This generalization enables us to describe quantum system with optical potential and channel couplings in a real time stochastic approach, which seems to give us a new insight into quantum mechanics beyond Copenhagen interpret

P. O. Fedichev

We discuss the formation of antihydrogen atoms ($\bar{\rm H}$) in an ultra-cold positron-antiproton plasma. For positron densities $n_p\agt 10^8$ cm$^{-3}$ the characteristic formation time of stable $\bar{H}$ is determined by collisional relaxation of highly excited atoms produced in the process of 3-body Thompson recombination. Relying on the mechanisms of

Bin Zhang, Yang Pang

Frame dependence of parton cascade results is studied for different schemes of doing cascade simulations. We show that different schemes do not always agree and results may have strong frame dependence. When the interaction range is on the order of mean free path and the collisions are done in the two particle center of mass frame, the results are not sensit

Attilio Cucchieri, Daniel Zwanziger

The static color-Coulomb potential is calculated as the solution of a non-linear integral equation. This equation has been derived recently as a self-consistency condition which arises in the Coulomb Hamiltonian formulation of lattice gauge theory when the restriction to the interior of the Gribov horizon is implemented. The potential obtained is in qualitat

B. S. Acharya

Using U-duality transformations we map perturbative Type IIA string theory compactified on a class of Joyce 7-manifolds to a D-strings on D-manifold description in Type IIB theory. For perturbative Type IIB theory on the same class of Joyce manifolds we use duality transformations to map to an M-theory, M-manifold description, which is an orientifold with fi