November 1997 arXiv papers — page 12

Marla C. Geha, Jon A. Holtzman, Jeremy R. Mould, John S. Gallagher

We present HST photometry for three fields in the outer disk of the LMC extending approximately four magnitudes below the faintest main sequence turnoff. We cannot detect any strongly significant differences in the stellar populations of the three fields based on the morphologies of the color-magnitude diagrams, the luminosity functions, and the relative num

M. M. Cirkovic, S. Samurovic, D. Ilic, J. Petrovic

In this work we shall sketch a further piece of evidence for the plausibility of hypothesis of galactic origin of Ly-$α$ forest absorption systems. Two basic premises of our discussion are (1) HDF redshift surface densities in the redshift interval 0<z<6; and (2) validity of low-redshift results on redshift coincidences, showing average absorption cross-sect

Sonia Brivio, Alessandro Verra

Let SU(2,1) be the moduli space of stable rank two vector bundles having fixed determinant of odd degree over a compact Riemann surface C. In this paper it is shown that the Theta divisor of SU(2,1) is very ample for every C. The proof is related to the study of the base locus of the pencil of divisors 2-theta in the Jacobian of C which is naturally associat

M. J. Duff, J. Liu, H. Lu, C. N. Pope

We show that six-dimensional supergravity coupled to tensor and Yang-Mills multiplets admits not one but two different theories as global limits, one of which was previously thought not to arise as a global limit and the other of which is new. The new theory has the virtue that it admits a global anti-self-dual string solution obtained as the limit of the cu

Dong Lai

The inner regions of accretion disks of weakly magnetized neutron stars are affected by general relativity and stellar magnetic fields. Even for field strengths sufficiently small so that there is no well-defined magnetosphere surrounding the neutron star, there is still a region in the disk where magnetic field stress plays an important dynamical role. We c

Nathan Berkovits, Barton Zwiebach

Closed string physical states are BRST cohomology classes computed on the space of states annihilated by $b_0^-$. Since $b_0^-$ does not commute with the operations of picture changing, BRST cohomologies at different pictures need not agree. We show explicitly that Ramond-Ramond (RR) zero-momentum physical states are inequivalent at different pictures, and p

Karl-Henning Rehren

The statistics of soliton sectors of massive 2D field theories is analysed. In the soliton field algebra, the non-local commutation relations are determined and Weak Locality, Spin-Statistics and CPT theorems are proven. These theorems depart from their usual appearance due to the broken symmetry connecting the inequivalent vacua. An interpretation in terms

Luca Capriotti, Ruggero Vaia, Alessandro Cuccoli, Valerio Tognetti

We present the results of Monte Carlo simulations for the antiferromagnetic classical XXZ model with easy-plane exchange anisotropy on the triangular lattice, which causes frustration of the spin alignment. The behaviour of this system is similar to that of the antiferromagnetic XY model on the same lattice, showing the signature of a Berezinskii-Kosterlitz-

Steen Hannestad, Georg Raffelt

Elastic scattering on nucleons, νN -> N ν, is the dominant supernova (SN) opacity source for μand τneutrinos. The dominant energy- and number-changing processes were thought to be νe^- -> e^- νand ν\bar ν<-> e^+ e^- until Suzuki (1993) showed that the bremsstrahlung process ν\bar νNN <-> NN was actually more important. We find that for energy exchange, the r

I. Aretxaga, R. J. Terlevich, B. J. Boyle

We present multicolour images of the hosts of three z=2 QSOs previously detected in R-band by our group. The luminosities, colours and sizes of the hosts overlap with those of actively star-forming galaxies in the nearby Universe. Radial profiles over the outer resolved areas roughly follow de Vaucouleur or exponential disk laws. These properties give suppor

A. Denner, T. Hahn

The cross-section for W^+W^- \to W^+W^- with arbitrarily polarized W bosons is calculated within the Electroweak Standard Model including the complete virtual and soft-photonic O(alpha) corrections. We show the numerical importance of the radiative corrections for the dominating polarized cross-sections and for the unpolarized cross-section. The numerical ac

S. Mallik, Krishnendu Mukherjee

We derive thermal QCD sum rules for the correlation function of two vector currents in the rho-meson channel. It takes into account the leading non-perturbative corrections from the additional operators, which appear due to the breakdown of Lorentz invariance at finite temperature. The mixing of the new operators has a drastic effect on their coefficients. T

Masahisa Matsuda, Morimitsu Tanimoto

Naturalness of the neutrino mass hierarchy and mixing is studied. First we select among 12 neutrino mixing patterns a few patterns, which could form the natural neutrino mass matrix. Further we show that if the Dirac neutrino mass matrix is taken as the natural one in the quark sector, then only two mixing patterns without the large mixing lead to the natura

Uros Seljak

Large-scale structure distorts the images of background galaxies, which allows one to measure directly the projected distribution of dark matter in the universe and determine its power spectrum. Here we address the question of how to extract this information from the observations. We derive minimum variance estimators for projected density reconstruction and

B. N. Narozhny, A. J. Millis, N. Andrei

We present evidence suggesting that spin transport in the gapless phase of the S=1/2 XXZ model is ballistic rather than diffusive. We map the model onto a spinless fermion model whose charge stiffness determines the spin transport of the original model. By means of exact numerical diagonalisation and finite size scaling we study both the stiffness and the le

K. Bering

We observe that an anti-symplectic manifold locally always admits a parity structure. The parity structure can be viewed as a complex-like structure on the manifold. This induces an odd metric and its Levi-Civita connection, and thereby a new notion of an odd Kaehler geometry. Oversimplified, just to capture the idea, the bosonic variables are ``holomorphic&

Bo-yu Hou, Wen-li Yang

In this paper, we construct a new Lax operator for the elliptic Calogero-Moser model with N=2. The nondynamical r-matrix structure of this Lax operator is also studied . The relation between our Lax operator and the Lax operator given by Krichever is also obtained.

Michael Martin Nieto, D. Rodney Truax

The results in the preceding comment are placed on a more general mathematical foundation.

C. Kiefer

I briefly review the role of the Wigner function in the study of the quantum-to-classical transition through interaction with the environment (decoherence).

H. Huber, F. Weber, M. K. Weigel, Ch. Schaab

We study the properties of neutron stars adopting relativistic equations of state of neutron star matter, calculated in the framework of the relativistic Brueckner-Hartree-Fock approximation for electrically charge neutral neutron star matter in beta-equilibrium. For higher densities more baryons (hyperons etc.) are included by means of the relativistic Hart

F. Cardarelli, B. Pasquini, S. Simula

The Drell-Hearn-Gerasimov sum rule for the nucleon is investigated within a relativistic constituent quark model formulated on the light-front. The contribution of the N - Delta(1232) transition is explicitly evaluated using different forms for the baryon wave functions and adopting a one-body relativistic current for the constituent quarks. It is shown that

M. A. Ivanov, Yu. L. Kalinovsky, P. Maris, C. D. Roberts

Semileptonic heavy -> heavy and heavy -> light meson transitions are studied as a phenomenological application of a heavy-quark limit of Dyson-Schwinger equations. Employing two parameters: E, the difference between the mass of the heavy meson and the effective-mass of the heavy quark; and Lambda, the width of the heavy-meson Bethe-Salpeter amplitude, we cal

Alexander A. Mikhalev, Vladimir Shpilrain, Jie-Tai Yu

This is a survey of recent progress in several areas of combinatorial algebra. We consider combinatorial problems about free groups, polynomial algebras, free associative and Lie algebras. Our main idea is to study automorphisms and, more generally, homomorphisms of various algebraic systems by means of their action on ``very small&#34; sets of elements, as

Agapitos Hatzinikitas, Koenraad Schalm, Peter van Nieuwenhuizen

We write general one-loop anomalies of string field theory as path integrals on a torus for the corresponding nonlinear sigma model. This extends the work of Alvarez-Gaumé and Witten from quantum mechanics to two dimensions. Higher world-volume loops contribute in general to nontopological anomalies and a formalism to compute these is developed. We claim tha

Mikhail Z. Iofa, Leopoldo A. Pando Zayas

We discuss charged black-hole solutions to the equations of motion of the string-loop-corrected effective action. At the string-tree level, these solutions provide backgrounds for the &#34;chiral null model&#34;. The effective action contains gravity, dilaton and moduli fields. Analytic solutions of the one-loop-corrected equations of motion are presented fo

T. Inagaki, T. Muta, S. D. Odintsov

Four-fermion interaction models are considered to be prototype models for dynamical symmetry breaking.The present review deals with recent developments in the studies of dynamical symmetry breaking in the four-fermion interaction models and their extension in curved spacetime. Starting with the Minkowski spacetime in dimension $D$ ($2 \leq D \leq 4$) the eff

A. Fayyazuddin, M. Spalinski

N=1 supersymmetric QCD is considered using the recently proposed picture of it as the world volume theory of a single M-theory fivebrane with two of its dimensions wrapped on a Riemann surface. The conditions under which a second M-theory brane can be introduced preserving some supersymmetry are analysed. Such configurations represent BPS saturated extended

Soo-Jong Rey

Q-ball configuration that represents oscillating or spinning closed membrane is constructed via M(atrix) theory. Upon gravitational collapse Q-balls are expected to form Schwarzschild black holes. For quasi-static spherical membrane, we probe spacetime geometry induced by monopole moment via D0-parton scattering off the Q-ball. We find a complete agreement w

T. Suyama, A. Tsuchiya

We investigate N_c=2 case of IIB matrix model, which is exactly soluble. We calculate the partition function exactly and obtain a finite result without introducing any cut-off. We also evaluate some correlation functions consisting of Wilson loops.

I. Ya. Aref&#39;eva, P. B. Medvedev, O. A. Rytchkov, I. V. Volovich

We consider the classical and quantum dynamics in M(atrix) theory. Using a simple ansatz we show that a classical trajectory exhibits a chaotic motion. We argue that the holographic feature of M(atrix) theory is related with the repulsive feature of energy eigenvalues in quantum chaotic system. Chaotic dynamics in N=2 supersymmetric Yang-Mills theory is also

Vittorio Del Duca, Carl R. Schmidt

We compute the virtual next-to-leading corrections to the impact factors or off-shell coefficient functions in the high-energy limit. When combined with the known real corrections, these results will provide the complete NLO corrections to the impact factors, which are necessary to use the BFKL resummation at NLL for jet production at both lepton-hadron and

M. Davier, A. Hoecker

We reevaluate the hadronic contribution to the running of the QED fine structure constant alpha(s) at s = M_Z^2. We use data from e+e- annihilation and tau decays at low energy and at the qq-bar thresholds, where resonances occur. Using so-called spectral moments and the Operator Product Expansion (OPE), it is shown that a reliable theoretical prediction of

Marco A. Diaz, Steve F. King, Douglas A. Ross

We discuss the one-loop radiative corrections to the reaction e^+ e^- -> X^+_a X^-_b, for a,b=1,2 where X^+_{1,2} are the charginos of the minimal supersymmetric standard model. We calculate the leading one loop radiative corrections involving loops of top, stop, bottom and sbottom quarks, working in the MS-bar scheme. At LEP2 we find positive radiative corr

O. Pisanti, L. Rosa

Studying Renormalization Group Equations for the four typical SO(10) spontaneous symmetry breaking patterns we find the existence of lower limits on neutrino masses.

Tord Riemann

The Z line shape is measured at LEP with an accuracy at the per mille level. Usually it is described in the Standard Model of electroweak interactions with account of quantum corrections. Alternatively, one may attempt different model-independent approaches in order to extract quantities like mass and width of the Z boson. If a fit deviates from that in the

A Donnachie, P V Landshoff

It is shown that colour transparency causes nonperturbative colour-singlet final-state interactions to have a negligible effect on the production rate and the dijet mass spectra in $e^+e^-\to WW$. However, the same cannot be said of nonperturbative colour-octet exchange, for which we show that there are indications of observable effects, though we are unable

F. Krüger, L. M. Sehgal

We summarize the results of two papers in which we have studied CP violation in inclusive and exclusive decays b -> d e^+e^-. Two CP-violating effects are calculated: the partial rate asymmetry between b and \bar{b} decay, and the asymmetry between e^- and e^+ spectra for an untagged B/\bar{B} mixture. These asymmetries, combined with the branching ratio, ca

J. -L. Kneur

We review how a specific resummation of the so-called &#34;delta-expansion&#34;, applied to the QCD Lagrangian, transforms the ordinary perturbative expansion in $α_s$ into an expansion in an arbitrary mass parameter, around the basic scale $\barΛ$. When applied to the pole mass, the resulting expression may be interpreted as a dynamical mass ansatz, to be o

M. Teper

I review what lattice QCD simulations have to tell us about the glueball spectrum. Talk given at HEP97, Jerusalem, August 1997.

A. Harindranath, Rajen Kundu, Asmita Mukherjee, James P. Vary

We investigate the twist four longitudinal structure function $F_{L}^{τ=4}$ of deep inelastic scattering and show that the integral of ${F_{L}^{τ=4} \over x}$ is related to the expectation value of the fermionic part of the light-front Hamiltonian density at fixed momentum transfer. We show that the new relation, in addition to providing physical intuition o

Chun Liu

The 1/N_c expansion of the heavy baryon Isgur-Wise functions is discussed. Because of the contracted SU(2N_f) light quark spin-flavor symmetry, the universality relations among the Isgur-Wise functions of Λ_b to Λ_c and Σ_b^{(*)} to Σ_c^{(*)} are valid up to the order of 1/N_c^2.

A. Hosaka, H. Toki, M. Takayama

We study theoretically the baryon spectra in terms of a deformed oscillator quark (DOQ) model. This model is motivated by confinement of quarks and chiral symmetry breaking, which are the most important non-perturbative phenomena of QCD. The minimization of the DOQ hamiltonian with respect to the deformation for each principal quantum number results in defor

Paul H. Frampton, Masayasu Harada

We calculate contributions to the oblique parameters $S$ and $T$ for leptoquarks and bileptons, and find phenomenological constraints on their allowed masses. Leptoquarks suggested by the neutral and charged current anomalies at HERA can give improved agreement with both $S$ and $T$. If bileptons are the only new states, the singly-charged one must be heavie

W. Bardeen, A. Duncan, E. Eichten, S. Perrucci

The calculation of the eta-prime hairpin diagram is carried out in the modified quenched approximation (MQA) in which the lattice artifact which causes exceptional configurations is removed by shifting observed poles at kappa<kappa_c in the quark propagators to the critical value of hop ping parameter. By this method, the eta-prime propagator can be accurate

T. Yoshié

Recent developments in calculations of the light hadron spectrum are reviewed. Particular emphasis is placed on discussion of to what extent the quenched spectrum agrees with experiment. Recent progress, both for quenched and full QCD, in reducing scaling violation with the use of improved actions is presented.

H. F. Dowker, R. S. Garcia

We consider certain interesting processes in quantum gravity which involve a change of spatial topology. We use Morse theory and the machinery of handlebodies to characterise topology changes as suggested by Sorkin. Our results support the view that that the pair production of Kaluza-Klein monopoles and the nucleation of various higher dimensional objects ar

Alberto García, Claus Lämmerzahl, Alfredo Macías, Eckehard W. Mielke

We generalize the formulation of the colliding gravitational waves to metric-affine theories and present an example of such kind of exact solutions. The plane waves are equipped with five symmetries and the resulting geometry after the collision possesses two spacelike Killing vectors.

S. V. Krasnikov

The use of &#34;handy singularities&#34; (i.e. singularities similar to those arising in the Deutch-Politzer space) enables one to avoid (almost) all known difficulties inherent usually to creation of time machines. A simple method is discussed for constructing a variety of such singularities. A few 3-dimensional examples are cited.

M. Kenmoku, H. Kubotani, E. Takasugi, Y. Yamazaki

We study the quantum theory of the spherically symmetric black holes. The theory yields the wave function inside the apparent horizon, where the role of time and space coordinates is interchanged. The de Broglie-Bohm interpretation is applied to the wave function and then the trajectory picture on the minisuperspace is introduced in the quantum as well as th

P. W. Brouwer

We compute the statistical distribution of the transmittance of a random waveguide with absorption in the limit of many propagating channels. We consider the average and fluctuations of the conductance T = tr t^{\dagger} t, where t is the transmission matrix, the density of transmission eigenvalues τ(the eigenvalues of t^{\dagger} t), and the distribution of

Nadav M. Shnerb

The equilibrium properties of flux lines pinned by columnar disorder are studied, using the analogy with the time evolution of a diffusing scalar density in a randomly amplifying medium. Near H_{c1}, the physical features of the vortices in the localized phase are shown to be determined by the density of states near the band edge. As a result, H_{c1} is inve

T. F. Scott, R. J. Ballagh, K. Burnett

The meanfield interaction in a Bose condensate provides a nonlinearity which can allow stable structures to exist in the meanfield wavefunction. We discuss a number of examples where condensates, modelled by the one dimensional Gross Pitaevskii equation, can produce gray solitons and we consider in detail the case of two identical condensates colliding in a

Patrik Henelius, S. M. Girvin, Anders W. Sandvik

We discuss the effects of fixing the winding number in quantum Monte Carlo simulations. We present a simple geometrical argument as well as strong numerical evidence that one can obtain exact ground state results for periodic boundary conditions without changing the winding number. However, for very small systems the temperature has to be considerably lower

J. -S. Caux, N. Taniguchi, A. M. Tsvelik

We consider Dirac fermions interacting with a disordered non-Abelian vector potential. The exact solution is obtained through a special type of conformal field theory including logarithmic correlators, without resorting to the replica or supersymmetry approaches. It is shown that the proper treatment of the conformal theory leads to a different multifractal

T. Antal, Z. Racz, A. Rakos, G. M. Schutz

The ground-state correlations are investigated for an isotropic transverse XY chain which is constrained to carry either a current of magnetization J_M or a current of energy J_E. We find that the effect of nonzero J_M on the large-distance decay of correlations is twofold: i) oscillations are introduced and ii) the amplitude of the power law decay increases

M. V. Mostovoy, M. T. Figge, J. Knoester

We study the effects of weak off-diagonal disorder on Peierls systems with a doubly degenerate ground state. We show that for these systems disorder in the electron hopping amplitudes induces a finite density of solitons in the minimal-energy lattice configuration of a single chain. These disorder-induced dimerization kinks are neutral and have spin 1/2. Usi

Erich J. Mueller, Paul M. Goldbart, Yuli Lyanda-Geller

The ability to support metastable current-carrying states in multiply-connected settings is one of the prime signatures of superfluidity. Such states are investigated theoretically for the case of trapped Bose condensed alkali gases, particularly with regard to the rate at which they decay via thermal fluctuations. The lifetimes of metastable currents can be

S. Schwegmann, A. P. Seitsonen, V. De Renzi, H. Dietrich

Oxygen adsorption onto Ru (10 bar 1 0) results in the formation of two ordered overlayers, i.e. a c(2 times 4)-2O and a (2 times 1)pg-2O phase, which were analyzed by low-energy electron diffraction (LEED) and density functional theory (DFT) calculation. In addition, the vibrational properties of these overlayers were studied by high-resolution electron loss

B. Revaz, J. -Y. Genoud, A. Junod, A. Erb

The low temperature specific heat C(B,T) of an YBa2Cu3O7.00 single crystal is measured from 1.2 to 10 K in magnetic fields up to 14 T. The anisotropic component Caniso(T,B)=C(T,B//c)-C(T,B//ab) is a pure vortex quantity obtained directly from experiment. It follows a scaling relation predicted recently for line nodes characteristic of d-wave vortices. Our ex

C. Morais Smith, Y. Dimashko, N. Hasselmann, A. O. Caldeira

We study the dynamics of the striped phase, which has previously been suggested to be the ground state of a doped antiferromagnet. Starting from the t-J model, we derive the classical equation governing the motion of the charged wall by using a ficticious spin model as an intermediate step. A wave-like equation of motion is obtained and the wall elasticity a

Shoji Yamamoto

Investigating quantum fluctuations in the ground states of S=1 quantum antiferromagnetic spin chains described by the bilinear-biquadratic Hamiltonian, we study a mechanism of the breakdown of the Haldane phase. Based on the valence-bond-solid structure, but replacing two links of them by triplet bonds (crackions), we construct a trial wave function which is

Henning Schomerus

We investigate classical and semiclassical aspects of codimension--two bifurcations of periodic orbits in Hamiltonian systems. A classification of these bifurcations in autonomous systems with two degrees of freedom or time-periodic systems with one degree of freedom is presented. We derive uniform approximations to be used in semiclassical trace formulas an

Anirban Sain, J. K. Bhattacharjee

We carry out a self consistent calculation of the structure functions in the dissipation range using Navier Stokes equation. Combining these results with the known structures in the inertial range, we actually propose crossover functions for the structure functions that takes one smoothly from the inertial to the dissipation regime. In the process the succes

Wei Zheng, Arthur F. Davidsen, Gerard A. Kriss

Based on the empirical formulas governing the distribution of Ly-a forest absorption, we use a Monte-Carlo technique to calculate the average HeII optical depth produced by these forest lines. A substantial contribution to HeII absorption arises from extremely tenuous regions of intergalactic gas that are beyond the observational limits for HI absorption.

B. Salasnich, A. Bressan, C. Chiosi

In this paper we present new models of massive stars based on recent advancements in the theory of diffusive mixing and a new empirical formulation of the mass-loss rates of red supergiant stars. We compute two sets of stellar models of massive stars with initial chemical composition [Z=0.008, Y=0.25] and [Z=0.020, Y=0.28]. Mass loss by stellar wind is also

Daniel Schaerer, William D. Vacca

Using the latest stellar evolution models, theoretical stellar spectra, and a compilation of observed emission line strengths from Wolf-Rayet (WR) stars, we construct evolutionary synthesis models for young starbursts. We explicitly distinguish between the various WR subtypes (WN, WC, WO), and we treat O and Of stars separately. We provide detailed predictio

J. Lesgourgues, D. Polarski, A. A. Starobinsky

A class of spatially-flat models with cold dark matter (CDM), a cosmological constant and a broken-scale-invariant (BSI) steplike primordial (initial) spectrum of adiabatic perturbations, generated in an exactly solvable inflationary model where the inflaton potential has a rapid change of its first derivative at some point, is confronted with existing obser

John Hultman, Daniel Kaellander

We present hydrodynamical simulations of the formation of galaxies in the mass range 10^9 - 10^13 solar masses, with the focus on the efficiency of gas cooling. The effect of a background UV radiation field, and the effect of metal enrichment of halo gas due to star formation and stellar evolution, are investigated. A background radiation field is found to s

Edward J. M. Colbert, Stefi A. Baum, Chris P. O&#39;Dea, Sylvain Veilleux

We present ROSAT PSPC and HRI images of eight galaxies selected from a distance-limited sample of 22 edge-on Seyfert galaxies. Kiloparsec-scale soft X-ray nebulae extend along the galaxy minor axes in three galaxies (NGC 2992, NGC 4388 and NGC 5506). The extended X-ray emission has 0.2-2.4 keV X-ray luminosities of $0.4-3.5 \times 10^{40} erg s^{-1}$. The X-

John Hultman, Daniel Kaellander

We present and test a code for two-fluid simulations of galaxy formation, one of the fluids being collision-less. The hydrodynamical evolution is solved through the SPH method while gravitational forces are calculated using a tree method. The code is Lagrangian, and fully adaptive both in space and time. A significant fraction gas in simulations of hierarchi

John P. Hughes

The hot gas in clusters of galaxies emits thermal bremsstrahlung emission that can be probed directly through measurements in the X-ray band with satellites like ROSAT and ASCA. Another probe of this gas comes from its effect on the cosmic microwave background radiation (CMBR): the hot cluster electrons inverse Compton scatter the CMBR photons and thereby di

F. Sylos Labini, M. Montuori

We investigate the statistical properties of the APM-Stromlo redshift survey by using the concepts and methods of modern Statistical Physics. We find that galaxy distribution in this survey exhibits scale invariant properties with fractal dimension $D = 2.1 \pm 0.1$, up to $\sim 40 \hmp$, i.e. the limit of its statistical validity, without any tendency towar

Ruth Durrer, Martin Kunz

In this work we present a partially new method to analyze fluctuations which are induced by causal scaling seeds. We show that the power spectra due to this kind of seed perturbations are determined by five analytic functions, which we determine numerically for a special example. We put forward the view that, even if recent work disfavors the models with cos

H. J. Mo

Recent observations have shown that (some) metal line absorption systems in QSO spectra arise from gas in galactic halos with radii much larger than the optical radii of galaxies. We show that the observed galaxy-absorber connections are natural results of galaxy formation in hierarchical cosmogonies, where galaxies form from gas cooling and condensation in

A. M. Atoyan, F. A. Aharonian

We study the temporal and spectral evolution of the radio flares detected from the relativistic ejecta in the microquasar GRS 1915+105, and develop a model which suggests that these flares are due to synchrotron radiation of relativistic electrons suffering adiabatic and radiative energy losses in fastly expanding plasmoids (radio clouds). Analytical solutio

Ewa L. Lokas

Using weakly nonlinear conditional PDF for the density field around an overdense region we find that the expected density contrast around a peak is always smaller while its rms fluctuation larger than in the linear case. We apply these results to the spherical model of collapse as developed by Hoffman & Shaham (1985) and find that in the case of open Univers

L. Verdes-Montenegro, M. S. Yun, J. Perea, A. del Olmo

A study of CO and FIR emission in a distance limited (z<0.03) complete sample of Hickson Compact Group (HCG) galaxies was conducted in order to examine the effects of their unique environment on the ISM and star formation activity. Ubiquitous tidal interactions in these dense groups would predict enhanced activities among the HCG galaxies compared to isolate

V. de Lapparent, G. Galaz, S. Arnouts, S. Bardelli

We describe the current status of the ESO-Sculptor Survey. The observational goal has been to produce a new multi-color photometric catalogue of galaxies in a region located near the southern galactic pole, complemented by a spectroscopic survey. The primary scientific objectives are (1) to map the spatial distribution of galaxies at 0.1 < z < 0.5 and (2) to

G. R. Knapp, K. Young, E. Lee, A. Jorissen

This paper describes observations of a new phenomenon in evolved mass-losing AGB stars: the presence of two winds with different expansion velocities. CO(2-1) and CO(3-2) line emission was observed for 45 AGB stars at high velocity resolution and double winds found in 20% of the sample. Highly asymmetric lines were found in six other stars. The data tentativ

Eriko Hironaka

In this paper we describe the complement of real line arrangements in the complex plane in terms of the boundary three-manifold of the line arrangement. We show that the boundary manifold of any line arrangement is a graph manifold with Seifert fibered vertex manifolds, and depends only on the incidence graph of the arrangement. When the line arrangement is

Clifford V. Johnson

The nature of M-theory on K3 X I, where I is a line interval, is considered, with a view towards formulating a `matrix theory&#39; representation of that situation. Various limits of this compactification of M-theory yield a number of well known N=1 six dimensional compactifications of the heterotic and type I string theories. Geometrical relations between t

NA44 Collaboration, I. G. Bearden et al

Experiment NA44 has measured proton and antiproton distributions at mid-rapidity in sulphur and proton collisions with nuclear targets at 200 and 450 GeV/c per nucleon respectively. The inverse slopes of transverse mass distributions increase with system size for both protons and antiprotons but are slightly lower for antiprotons. this could happen if antipr

Daniel Kabat, Washington Taylor

We consider membranes of spherical topology in uncompactified Matrix theory. In general for large membranes Matrix theory reproduces the classical membrane dynamics up to 1/N corrections; for certain simple membrane configurations, the equations of motion agree exactly at finite N. We derive a general formula for the one-loop Matrix potential between two fin

A. Pineda, J. Soto

We present a simple derivation of the Lamb shift using effective field theory techniques and dimensional regularisation.

O. F. Dayi

A 3-dimensional non-abelian gauge theory was proposed by Jackiw and Pi to create mass for the gauge fields. However, the quadratic action obtained by switching off the non-abelian interactions possesses more gauge symmetries than the original one, causing some difficulties in quantization. Jackiw and Pi proposed another action by introducing new fields, whos

F. Abe

We observe hadronic W decays in t-tbar -> W (-> l nu) + >= 4 jet events using a 109 pb-1 data sample of p-pbar collisions at sqrt{s} = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). A peak in the dijet invariant mass distribution is obtained that is consistent with W decay and inconsistent with the background prediction by 3.3 standard devia

A. Albrecht, R. A. Battye, J. Robinson

We calculate predictions from wide class of `active&#39; models of cosmic structure formation which allows us to scan the space of possible defect models. We calculate the linear cold dark matter power spectrum and Cosmic Microwave Background (CMB) anisotropies over all observable scales using a full linear Einstein-Boltzmann code. Our main result, which has

J. Hermisson, U. Grimm

We consider Ising quantum chains with quenched aperiodic disorder of the coupling constants given through general substitution rules. The critical scaling behaviour of several bulk and surface quantities is obtained by exact real space renormalization.

Cesar Gomez

We study N=1 four dimensional gluodynamics in the context of M-theory compactifications on elliptically fibered Calabi-Yau fourfolds. Gaugino condensates, θ-dependence, Witten index and domain walls are considered for singularities of type $\hat{A}_{n-1}$ and $\hat{D}_{n+4}$. It is shown how the topology of intersections among the irreducible components defi

Roberto Trasarti-Battistoni

We present a large catalog of loose groups of galaxies in the Southern Galactic Hemisphere, selected from the Perseus-Pisces redshift Survey (PPS). Particular care is taken in order to obtain group samples as homogeneous as possible to previously published catalogs. All our catalogs contain about 200 groups, significantly more than in most previous studies w

Anders Irbäck, Carsten Peterson, Frank Potthast, Erik Sandelin

A new method for sequence optimization in protein models is presented. The approach, which has inherited its basic philosophy from recent work by Deutsch and Kurosky [Phys. Rev. Lett. 76, 323 (1996)] by maximizing conditional probabilities rather than minimizing energy functions, is based upon a novel and very efficient multisequence Monte Carlo scheme. By c

Paul M. Goldbart, Daniel E. Sheehy

Excitations of the antiferromagnetic state that resemble antiferromagnetic hedgehogs at large distances but are predominantly superconducting inside a core region are discussed within the context of Zhang&#39;s SO(5)-symmetry-based approach to the physics of high-temperature superconducting materials. Nonsingular, in contrast with their hedgehog cousins in p

A. A. Sen, N. Banerjee

A recent investigation shows that a local gauge string with a phenomenological energy momentum tensor, as prescribed by Vilenkin, is inconsistent in Brans-Dicke theory. In this work it has been shown that such a string is consistent in a more general scalar tensor theory where $ω$ is function of the scalar field.A set of solutions of full nonlinear Einstein&

Fu-Guang Cao, Tao Huang

The large-$Q^2$ behavior of $η_c$-$γ$ and $η_b$-$γ$ transition form factors, $F_{η_cγ}(Q^2)$ and $F_{η_bγ}(Q^2)$ are analyzed in the framework of light-cone perturbative QCD with the heavy quark ($c$ and $b$) mass effect, the parton&#39;s transverse momentum dependence and the higher helicity components in the light-cone wave function are respected. It is po

Kazuo Hosomichi

We calculate semiclassically the emission rate of spin 1/2 particles from charged, nonrotating black holes in D=5,N=8 supergravity. The relevant Dirac equation is solved by the same approximation as in the bosonic case. The resulting expression for the emission rate has a form which is predicted from D-brane effective field theory.

Richard Easther, Kei-ichi Maeda

We demonstrate the existence of chaos in realistic models of two-field inflation. The chaotic motion takes place after the end of inflation, when the fields are free to oscillate and their motion is only lightly damped by the expansion of the universe. We then investigate whether the presence of chaos affects the predictions of two-field models, and show tha

Jun-ichiro Kishine, Kenji Yonemitsu

Physical nature of dimensional crossovers in weakly coupled Hubbard chains and ladders has been discussed within the framework of the perturbative renormalization-group approach. The difference between these two cases originates from different universality classes which the corresponding isolated systems belong to.

Karl-Peter Marzlin, Weiping Zhang

We study the creation of vortex states in a trapped Bose-Einstein condensate by a rotating force. For a harmonic trapping potential the rotating force induces only a circular motion of the whole condensate around the trap center which does not depend on the interatomic interaction. For the creation of a pure vortex state it is necessary to confine the atoms

Karol Zyczkowski, Wojciech Slomczynski

We define a metric in the space of quantum states taking the Monge distance between corresponding Husimi distributions (Q--functions). This quantity fulfills the axioms of a metric and satisfies the following semiclassical property: the distance between two coherent states is equal to the Euclidean distance between corresponding points in the classical phase

E. Oset, A. Ramos

The s-wave meson-nucleon interaction in the $S = -1$ sector is studied by means of coupled-channel Lippmann Schwinger equations, using the lowest order chiral Lagrangian and a cut off to regularize the loop integrals. The method reproduces succesfully the $Λ(1405)$ resonance and the $K^- p \to K^- p, \bar{K}^0 n, π^0 Λ, π^0 Σ, π^+ Σ^-, π^- Σ^+$ cross section