January 1998 arXiv papers — page 15

Eric G. Blackman

The origin and sustenance of large scale galactic magnetic fields has been a long standing and controversial astrophysical problem. Here an alternative to the ``standard'' $\a-Ω$ mean field dynamo and primordial theories is pursued. The steady supply of supernovae induced turbulence exponentiates the total field energy, providing a significant seed m

D. Branch

The focus of this review is the work that has been done during the 1990s on using Type Ia supernovae (SNe Ia) to measure the Hubble constant ($H_0$). SNe Ia are well suited for measuring $H_0$. A straightforward maximum-light color criterion can weed out the minority of observed events that are either intrinsically subluminous or substantially extinguished b

M. Catelan

Recent Hipparcos results have lent support to the idea that RR Lyrae variables in the halo field and in globular clusters differ in luminosity by ~0.2mag. In this Letter, we study the pulsation properties of RR Lyraes in clusters with distances determined via main-sequence fitting to Hipparcos parallaxes for field subdwarfs, and compare them with the propert

Hien D. Tran, Marshall H. Cohen, Patrick M. Ogle, Robert W. Goodrich

We present optical spectropolarimetric and imaging polarimetric observations of four high-redshift radio galaxies (HzRGs) obtained with the 10-m Keck I telescope. A broad Mg II emission line is detected in the total and polarized flux spectra of 3C 265 and 3C 277.2. The fractional polarization is high, and both it and the position angle are constant with wav

J. M. Miralles, R. Pello

This paper addresses the problem of detecting high-redshift clustering in deep photometric surveys. We have used photometric redshifts to select different samples of galaxies in the HDF, in order to study their clustering properties within the 2.5<z<4.5 domain, in redshift bins of 0.5, using different techniques. A strong clustering signal is found for redsh

E. Schinnerer, A. Eckart, L. J. Tacconi

We have investigated the ISM of the I Zw 1 QSO host galaxy with Plateau de Bure mm-interferometry and high angular resolution near-infrared imaging spectroscopy. We have detected a circumnuclear gas ring of diameter ~ 1.5&#39;&#39; (1.8 kpc) in its millimetric CO line emission and have mapped the disk and the spiral arms of the host galaxy in the ^{12}CO(1-0

Gustavo A. Medina Tanco

Three pairs of possibly correlated ultra-high energy cosmic ray events were reported by Hayashida et al (1996). Here we calculate the propagation of the corresponding particles through both the intergalactic and galactic magnetic fields. The large scale disc and halo magnetic components are approximated by the models of Stanev (1997). The intergalactic magne

J. A. Shrauner, J. H. Taylor, G. Woan

We have searched the northern sky for pulsars at the low radio frequency of 81.5 MHz, using the 3.6-hectare array at Cambridge, England. The survey covered most of the sky north of declination -20 deg and provided sensitivities of order 200 mJy for pulsars not too close to the galactic plane. A total of 20 pulsars were detected, all of them previously known.

T. Neukirch, P. C. H. Martens

A self-consistent mathematical description of the magnetic field of fluted sunspot penumbrae is presented. This description is based on an expansion of the nonlinear force-free magnetohydrostatic equations written in cylindrical coordinates. The lowest order solutions are mathematically equivalent to laminated force-free equilibria in Cartesian geometry. The

Urs Achim Wiedemann

Multiparticle symmetrization effects are contributions to the spectra of Bose-symmetrized states which are not the product of pairwise correlations. Usually they are neglected in particle interferometric calculations which aim at determining the geometry of the boson emitting source from the measured momentum distributions. Based on a method introduced by Za

Andrew A. de Laix, Mark Trodden, Tanmay Vachaspati

We analyze the core dynamics of critically coupled, superheavy gauge vortices in the (2+1) dimensional Einstein-Abelian-Higgs system. By numerically solving the Eistein and field equations for various values of the symmetry breaking scale, we identify the regime in which static solutions cease to exist and topological inflation begins. We explicitly include

A. Kercek, W. Hillebrandt, J. Truran

We present the results of two-dimensional calculations of turbulent nuclear burning of hydrogen-rich material accreted onto a white dwarf of 1 solar mass. The main aim of the present paper is to investigate the question as to whether and how the general properties of the burning are affected by numerical resolution effects. In particular, we want to see whet

Sang-Jin Sin

We study the holomorphic properties of the MQCD by comparing the super-potentials in MQCD and the gauge theory. First we show that the super-potential defined as an integral of three form is NOT appropriate for generic situation with quarks. We report a resolution of the problem which works for the brane configurations of 90 degree rotation, including the tr

Gaetano Fiore

Given M copies of a q-deformed Weyl or Clifford algebra in the defining representation of a quantum group $G_q$, we determine a prescription to embed them into a unique, inclusive $G_q$-covariant algebra. The different copies are &#34;coupled&#34; to each other and are naturally ordered into a &#34;chain&#34;. In the case $G_q=SL_q(N)$ a modified prescriptio

Jay A. Frogel, Andrew Gould

A star passing within $\sim 10^4 \au$ of the Sun would trigger a comet shower that would reach the inner solar system about 0.18 Myr later. We calculate a prior probability of ~0.4% that a star has passed this close to the Sun but that the comet shower has not yet reached the Earth. We search the HIPPARCOS catalog for such recent close-encounter candidates a

H. P. Nilles, M. Olechowski, M. Yamaguchi

We consider hidden sector supersymmetry breakdown in the strongly coupled heterotic $E_8\times E_8$ theory of Hořava and Witten. Using effective field theory methods in four dimensions, we can show that gravitational interactions induce soft breaking terms in the observable sector that are of order of the gravitiono mass. We apply these methods to the mechan

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

We reexamine in detail the problem of fermions interacting with a non-Abelian random vector potential. Without resorting to the replica or supersymmetry approaches, we show that in the limit of infinite disorder strength the theory possesses an exact solution which takes the form of a logarithmic conformal field theory. We show that the proper treatment of t

Arun Paramekanti, Nandini Trivedi, Mohit Randeria

We derive several upper bounds for the superfluid stiffness $D_s$ for Bose and Fermi systems in terms of expectation values of local operators using linear response theory and variational methods. These give insight into the non-trivial dependence of $D_s$ on parameters such as disorder and interaction in systems with broken continuous translational invarian

Emil M. Prodanov, Siddhartha Sen

Using a group-invariant version of the Faddeev-Popov method we explicitly obtain the partition functions of the Self-Dual Model and Maxwell-Chern-Simons theory. We show that their ratio coincides with the partition function of abelian Chern-Simons theory to within a phase factor depending on the geometrical properties of the manifold.

E. Orignac, T. Giamarchi

We consider two coupled strongly correlated bosonic chains. We derive the phase diagram of the pure system and obtain an antisymmetric charge density wave, a 4k_F charge density wave, a superfluid phase and a second superfluid phase which is a condensate of boson pairs. We consider the effect of a weak disorder on that system and show that the superfluid pha

Yuji Koike

After reviewing QCD definitions of the chiral-odd spin-dependent parton distributions $h_1(x,Q^2)$ and h_L(x,Q^2), I will summarize the main feature of the recent two results in perturbative QCD: (i) Next-to-leading order $Q^2$ evolution of h_1(x,Q^2). (ii) Leading order Q^2 evolution of the twist-3 distribution h_L(x,Q^2) and the universal simplification of

G. Drobny, B. Hladky, V. Buzek

We present a universal algorithm for an efficient deterministic preparation of an arbitrary two--mode bosonic state. In particular, we discuss in detail preparation of entangled states of a two-dimensional vibrational motion of a trapped ion via a sequence of laser stimulated Raman transitions. Our formalism can be generalized for multi-mode bosonic fields.

G. Bouzerar, A. P. Kampf, G. I. Japaridze

We present a detailed numerical analysis of the low energy excitation spectrum of a frustrated and dimerized spin $S=1/2$ Heisenberg chain. In particular, we show that in the commensurate spin--Peierls phase the ratio of the singlet and triplet excitation gap is a universal function which depends on the frustration parameter only. We identify the conditions

V. Berezinsky

Decaying superheavy particles can be produced by Topological Defects or, in case they are quasi-stable, as relics from the early Universe. The decays of these particles can be the sources of observed Ultra High Energy Cosmic Rays ($E \sim 10^{10} - 10^{12} GeV$). The Topological Defects as the UHE CR sources are critically reviewed and cosmic necklaces and m

Manuel Drees, Monoranjan Guchait, Probir Roy

Limits are derived on models with extended Higgs sectors, including the Minimal Supersymmetric Standard Model (MSSM), by exploiting the data on $τ^+ τ^- + $ 2 jets final states, used by the CDF collaboration to place limits on third generation leptoquarks. The main observation here is that both leptoquark production and associated $b \bar{b}$ Higgs productio

J. Satooka, H. Aruga Katori, A. Tobo, K. Katsumata

Heat capacity measurements on the prototypical three-dimensional random-field Ising model compound Fe0.58Zn0.42F2 have been performed in both of the field-cooling (FC) and zero-field-cooling (ZFC) procedures. There is no evidence of hysteresis between the FC and ZFC protocols within the experimental accuracy. The absence of hysteresis is interpreted based on

Kei-Ichi Kondo

We propose a reformulation of Yang-Mills theory as a perturbative deformation of a novel topological (quantum) field theory. We prove that this reformulation of the four-dimensional QCD leads to quark confinement in the sense of area law of the Wilson loop. First, Yang-Mills theory with a non-Abelian gauge group G is reformulated as a deformation of a novel

J. Finkelstein

There has been considerable discussion of the claim by Stapp [Am. J. Phys. 65, 300 (1997)] that quantum theory is incompatible with locality. In this note I analyze the meaning of some of the statements used in this discussion.

V. A. Kalatsky, V. L. Pokrovsky

We predict that large moments $J$, placed into a crystal field with the cubic point symmetry group, differ by their spectrum and magnetic properties. E. g., properties of the odd-integer moments are different from those of the even-integer. The effect is due to Berry&#39;s phases gained by the moment, when it tunnels between minima of the external field. Two

Vladimir Buzek, Mark Hillery

We review our recent work on the universal (i.e. input state independent) optimal quantum copying (cloning) of qubits. We present unitary transformations which describe the optimal cloning of a qubit and we present the corresponding quantum logical network. We also present network for an optimal quantum copying ``machine&#39;&#39; (transformation) which prod

Masahide Sasaki, Tsuyoshi Sasaki-Usuda, Masayuki Izutsu, Osamu Hirota

This was also extended from the previous article quant-ph/9705043, especially in a realization of the decoding process.

Yu. A. Alexandrov, M. Clement, F. Dropmann, A. Fournier

A high-intensity hyperon beam was constructed at CERN to deliver Sigma- to experiment WA89 at the Omega facility and operated from 1989 to 1994. The setup allowed rapid changeover between hyperon and conventional hadron beam configurations. The beam provided a Sigma-flux of 1.4 x 10^5 per burst at mean momenta between 330 and 345 Gev/c, produced by about 3 x

J. Baehr, H. -J. Grabosch, V. Kantserov, H. Leich

Using scintillator tile technology several square meters of plastic scintillator are read out by only two photomultiplier with a time precision of about 1.5 nsec. Two examples are discussed to build a detector based on this technology to search for cosmic muons and neutrinos.

H. Leich, R. Nahnhauer, R. Shanidze

The advantages and possibilities of fiber technology for the detection of particles in 500 GeV e+e- reactions are considered. It is suggested to build a fast trigger which could be used also for intermediate tracking. A fiber preshower in front of the electromagnetic calorimeter would allow to identify electrons and photons with a space precision better than

E. C. Aschenauer, J. Baehr, V. Gapienko, B. Hoffmann

A fiber detector concept is suggested allowing to registrate particles within less than 100 nsec with a space point precision of about 0.1 mm at low occuppancy. The fibers should be radiation hard for 1 Mrad/year. Corresponding prototypes have been build and tested at a 3 GeV electron beam at DESY. Preliminary results of these tests indicate that the design

Jeffrey T. Sheats

Let q be a power of a prime p. We prove an assertion of Carlitz which takes q as parameter. Diaz-Vargas&#39; proof of the Riemann Hypothesis for the Goss zeta function for F_p[T] depends on his verification of Carlitz&#39;s assertion for the specific case q = p. Our proof of the general case allows us to extend Diaz-Vargas&#39; proof to F_q[T].

E. Batista, J. F. Gomes, I. J. Lautenschleguer

In this paper we employ the construction of Dirac bracket for the remaining current of $sl(2)_q$ deformed Kac-Moody algebra when constraints similar to those connecting the $sl(2)$-WZW model and the Liouville theory are imposed and show that it satisfy the q-Virasoro algebra proposed by Frenkel and Reshetikhin. The crucial assumption considered in our calcul

Liviu I. Nicolaescu

We express the number of lattice points inside certain simplices via Dedekind-Rademacher sums. As an application, we prove a conjecture of Kronheimer and Mrowka in the special case of Brieskorn spheres (with at most 4 singular fibers). This conjecture relates the Euler characteristic of the Seiberg-Witten-Floer homology to the Casson invariant.

Dmitri Alekseevsky, Andreas Kriegl, Mark Losik, Peter W. Michor

We show that one can lift locally real analytic curves from the orbit space of a compact Lie group representation, and that one can lift smooth curves even globally, but under an assumption.

D. Alekseevsky, J. Grabowski, G. Marmo, P. W. Michor

Lie bialgebra structures are reviewed and investigated in terms of the double Lie algebra, of Manin- and Gauß-decompositions. The standard R-matrix in a Manin decomposition then gives rise to several Poisson structures on the correponding double group, which is investigated in great detail.

Dmitri Alekseevsky, Andreas Kriegl, Mark Losik, Peter W. Michor

We clarify the question whether for a smooth curve of polynomials one can choose the roots smoothly and related questions. Applications to perturbation theory of operators are given.

Feng Luo

Using the works of Gervais, Harer, Hatcher and Thurston and others, we show that the mapping class group of a compact orientable surface has a presentation so that the generators are the set of all Dehn twists and the relations are supported in subsurfaces homeomorphic to the one-holed torus or the four-holed sphere. It turns out that all the relations were

Feng Luo

Given a compact orientable surface with finitely many punctures $Σ$, let $\Cal S(Σ)$ be the set of isotopy classes of essential unoriented simple closed curves in $Σ$. We determine a complete set of relations for a function from $\Cal S(Σ)$ to $\bold R$ to be the geodesic length function of a hyperbolic metric with geodesic boundary and cusp ends on $Σ$. As

Peter W. Michor, Hermann Schichl

On a fiber bundle without structure group the action of the gauge group (the group of all fiber respecting diffeomorphisms) on the space of (generalized) connections is shown not to admit slices.

Pavel Exner, Simeon A. Vugalter

We discuss the discrete spectrum of N particles in a curved planar waveguide. If they are neutral fermions, the maximum number of particles which the waveguide can bind is given by a one-particle Birman-Schwinger bound in combination with the Pauli principle. On the other hand, if they are charged, e.g., electrons in a bent quantum wire, the Coulomb repulsio

S. Majid

We develop a general theory of `quantum&#39; diffeomorphism groups based on the universal comeasuring quantum group $M(A)$ associated to an algebra $A$ and its various quotients. Explicit formulae are introduced for this construction, as well as dual quasitriangular and braided R-matrix versions. Among the examples, we construct the $q$-diffeomorphisms of th

E. Celeghini, S. De Martino, S. De Siena, A. Iorio

The algebraic structure of Thermo Field Dynamics lies in the $q$-deformation of the algebra of creation and annihilation operators. Doubling of the degrees of freedom, tilde-conjugation rules, and Bogoliubov transformation for bosons and fermions are recognized as algebraic properties of $h_{q}(1)$ and of $h_{q}(1|1)$, respectively.

Stephen F. Hewson

In this note we discuss the theory of super-threebranes in a spacetime of signature (10,2). Upon reduction, the threebrane provides us with the classical representations of the M-2-brane and the type IIB superstring. Many features of the original super (2+2)-brane theory are clarified. In particular, the (10,2) superspace and the spinors required to construc

Giuseppe Carlino, Kenichi Konishi, Haruhiko Terao

Physical quark-number charges of dyons are determined, via a formula which generalizes that of Witten for the electric charge, in N=2 supersymmetric theories with $SU(2) \times U(1)^{N_f} $ gauge group. The quark numbers of the massless monopole at a nondegenerate singularity of QMS turn out to vanish in all cases. A puzzle related to CP invariant cases is s

Andreas Wipf

This review gives an introduction into problems, concepts and techniques when quantizing matter fields near black holes. The first part focusses on quantum fields in general curved space-times. The second part is devoted to a detailed treatment of the Unruh effect in uniformly accelerated frames and the Hawking radiation of black holes. Paricular emphasis is

Nobuyoshi Ohta, Jian-Ge Zhou

The partition function in Matrix theory is constructed by Euclidean path integral method. The D0-branes, which move around in the finite region with a typical size of Schwarzschild radius, are chosen as the background. The mass and entropy of the system obtained from the partition function contain the parameters of the background. After averaging the mass an

Robert Carroll

We collect a number of facts and conjectures concerning Whitham theory and the renormalization group. Some explicit relations and problems are indicated in the context of N=2 susy Yang-Mills.

Hsin-Chia Cheng

Measurements of supersymmetric particle couplings provide important verification of supersymmetry. If some of the superpartners are at the multi-TeV scale, they will escape direct detection at planned future colliders. However, such particles induce nondecoupling corrections in processes involving the accessible superparticles through violations of the super

M. Diehl, T. Gousset

We investigate the relevance of time ordering in the definition of off-diagonal parton distributions in terms of products of fields. The method we use easily allows determination of their support properties and provides a link to their interpretation from a parton point of view. It can also readily be applied to meson distribution amplitudes.}

Minos Axenides, Leandros Perivolaropoulos, Mark Trodden

We demonstrate the existence of global monopole and vortex configurations whose core exhibits a phase structure. We determine the critical values of parameters for which the transition from the symmetric to the non-symmetric phase occurs and discuss the novel dynamics implied by the non-symmetric cores for defect interactions. We model phase transitions in t

Changhao Jin

We make an analysis of the hadronic invariant mass spectrum in inclusive charmless semileptonic B meson decays in a QCD-based approach. The decay width is studied as a function of the invariant mass cut. We examine their sensitivities to the parameters of the theory. The theoretical uncertainties in the determination of $|V_{ub}|$ from the hadronic invariant

Ariel Zhitnitsky

The main subject of these lectures is the Nonperturbative Wave Functions. We describe some nonperturbative methods (like QCD sum rules, dispersion relations, duality etc) in order to study this object. We also consider some applications of the obtained results, such as form factors, inclusive amplitudes and diffractive electroproduction. Finally, we discuss

E. Levin

This is the first part of my lectures on the Pomeron structure which I am going to read during this academic year at the Tel Aviv university. The main goal of these lectures is to remind young theorists as well as young experimentalists of what are the Reggeons that have re-appeared in the high energy phenomenology to describe the HERA and the Tevatron data.

P. Sawicki

We apply a simple analytical criterion for locating critical temperatures to Potts models on square and triangular lattices. In the self-dual case, i.e. on the square lattice we reproduce known exact values of the critical temperature and derive the internal energy of the model at the critical point. For the Potts model on the triangular lattice we obtain ve

Ted Jacobson

A brief survey of the major themes and developments of black hole thermodynamics in the 1990&#39;s is given, followed by summaries of the talks on this subject at MG8 together with a bit of commentary, and closing with a look towards the future.

T. Damour, B. R. Iyer, B. S. Sathyaprakash

Gravitational waves from inspiralling compact binaries can be reliably extracted from a noisy detector output only if the template used in the detection is a faithful representation of the true signal. In this article we suggest a new approach to constructing faithful signal models.

V. B. Geshkenbein, L. B. Ioffe, A. J. Millis

We show that recent measurements of the magnetic field dependence of the magnetization, specific heat and resistivity of overdoped $T_c \sim 17K$ $Tl_{2}Ba_{2}CuO_{6+δ}$ in the vicinity of the superconducting $H_{c2}$ imply that the vortex viscosity is anomalously small and that the material studied is inhomogeneous with small, a few hundred $Å$, regions in

Maura Sassetti, Bernhard Kramer

We show that the low-energy peak in the polarized resonant Raman spectra of quantum wires, which is commonly associated with ``single particle excitations&#39;&#39;, can be interpreted as signature of intra-band collective spin excitations. A broad maximum in the resonant depolarized spectra is predicted to exist above the frequency of the spin density excit

Philippe Claudin, Jean-Philippe Bouchaud

When some granular material contained into a silo is pushed upwards with a piston, an irregular stick-slip motion of the system of grains is observed. We show how one can adapt the `Scalar Arching Model&#39; -- proposed as a model for giant stress fluctuations in silos -- in order to describe this stick-slip phenomenon. As a function of the sensitivity of th

Erik Sorensen, Michel Gingras, David Huse

The fixed point structure of the 2D 3-state random-bond Potts model with a bimodal ($\pm$J) distribution of couplings is for the first time fully determined using numerical renormalization group techniques. Apart from the pure and T=0 critical fixed points, two other non-trivial fixed points are found. One is the critical fixed point for the random-bond, but

Stefano Lise, Attilio L. Stella

We introduce spatial inhomogeneities (boundaries) in a random neighbor version of the Olami, Feder and Christensen model [Phys. Rev. Lett. 68, 1244 (1992)] and study the distributions of avalanches starting both from the bulk and from the boundaries of the system. Because of their clear geophysical interpretation, two different boundary conditions have been

M. Kolesik, M. A. Novotny, Per Arne Rikvold

Iron sesquilayers are ultrathin films with coverages between one and two atomic monolayers. They consist of an almost defect-free monolayer with compact islands of a second atomic layer on top. This variation of the film thickness results in a strong interaction between domain walls and the island structure. It makes these systems an ideal laboratory to stud

G. Lamoureux, A. Caillé, D. Sénéchal

In order to understand the possible sequence of transitions from the disordered columnar phase to the helical phase in hexa(hexylthio)triphenylene (HHTT), we study a three-dimensional planar model with octupolar interactions inscribed on a triangular lattice of columns. We obtain thermal phase diagrams using a mean-field approximation and Monte Carlo simulat

B. Binz, X. Zotos, D. Baeriswyl

The t-J model with constant t and J between any pair of sites is studied by exploiting the symmetry of the Hamiltonian with respect to site permutations. For a given number of electrons and a given total spin the exchange term simply yields an additive constant. Therefore the real problem is to diagonalize the &#34;t- model&#34;, or equivalently the infinite

D. Mihailovic, B. Podobnik, J. Demsar, G. Wagner

We report new time-resolved data of quasiparticle relaxation and Cooper pair recombination dynamics in YBa_2Cu_3O_{7-δ}, measured as a function of temperature and doping δusing femtosecond optical spectroscopy. The data show the existence of a normal state pseudo-gap for in-plane charge excitations below T* and an unusual divergence of the quasiparticle rela

Anathnath Ghosh, S. N. Karmakar

We present an exact real-space renormalization group (RSRG) method for evaluating the dynamic structure factor of an infinite one-dimensional quasiperiodic period-doubling (PD) lattice. We observe that for every normal mode frequency of the chain, the dynamic structure factor $S(q,ω)$ always exhibits periodicity with respect to the wave vector $q$ and the pr

S. A. Mikhailov

A general electrodynamic theory of a grating coupled two dimensional electron system (2DES) is developed. The 2DES is treated quantum mechanically, the grating is considered as a periodic system of thin metal strips or as an array of quantum wires, and the interaction of collective (plasma) excitations in the system with electromagnetic field is treated with

Michael Stapper, Tanniemola B. Liverpool

We present a field-theoretic renormalization group (RG) analysis of a dilute solution of flexible, screened polyelectrolyte chains (Debye-Hueckel chains) in a polar solvent. We perform a virial expansion to calculate the scaling dependence of the Osmotic pressure on the chain density, chain size and screening length. The formalism is developed for general ch

Anathnath Ghosh, S. N. Karmakar

We present an analytical method for finding all the electronic eigenfunctions and eigenvalues of the aperiodic Thue-Morse lattice. We prove that this system supports only extended electronic states which is a very unusual behavior for this class of systems, and so far as we know, this is the only example of a quasiperiodic or aperiodic system in which critic

Suresh G. Mishra, P. A. Sreeram

Specific heat curves for various pressures, in many correlated electron systems, have been seen to cross at a point. We analyze this behavior using the spin fluctuation theory. It is found that when the system is considered near a ferromagnetic instability, the curves cross at one point and for systems near an antiferromagnetic instability, they cross at two

N. S. Ananikian, N. Sh. Izmailian, K. A. Oganessyan

The Ising spin - S model on recursive p - polygonal structures in the external magnetic field is considered and the general form of the free energy and magnetization for arbitrary spin is derived. The exact relation between the free energies on infinite entire tree and on its infinite &#34;interior&#34; is obtained.

Takao Morinari

We derive the effective Hamiltonian for the composite fermion in double-layer quantum Hall systems with inter-layer tunneling at total Landau-level filling factor $ν=1/m$, where $m$ is an integer. We find that the ground state is the triplet p-wave BCS pairing state of the composite fermions. At $ν=1/2$, the ground state of the system evolves from the Halper

David Avnir, Ofer Biham, Daniel A. Lidar, Ofer Malcai

The notion of the abundance of fractals is critically re-examined in light of surprising data regarding the scaling range in empirical reports on fractality.

R. Benzi, L. Biferale, F. Toschi

Multiscale correlation functions in high Reynolds number experimental turbulence and synthetic signals are investigated. Fusion Rules predictions as they arise from multiplicative, almost uncorrelated, random processes for the energy cascade are tested. Leading and sub-leading contribution, in both the inertial and viscous ranges, are well captured by assumi

Jie Liu, Shi-Gang Chen, Bambi Hu

In this paper we describe the rescattering process in optical field ionization through a one-dimensional model, which improves the well-known quasistatic model by adding the smoothed Coulomb potential in its second step. The above-threshold ionization spectra and high-order harmonic generation are calculated from this model. They are qualitatively in agreeme

A. Parravano, M. G. Cosenza

A method to predict the emergence of different kinds of ordered collective behaviors in systems of globally coupled chaotic maps is proposed. The method is based on the analogy between globally coupled maps and a map subjected to an external drive. A vector field which results from this analogy appears to govern the transient evolution of the globally couple

Henry C. Ferguson

A variety of subtle, and not-so-subtle selection effects influence the interpretation of galaxy counts, sizes and redshift distributions in the Hubble Deep Field. Comparison of the different HDF catalogs available in the literature and on the world-wide-web reveals generally good agreement, although the effects of different isophotal thresholds and different

Henry C. Ferguson, Arif Babul

Several independent lines of reasoning suggest that many of the very faint (B > 24) blue galaxies are low-mass objects that experienced a short epoch of star formation at redshifts 0.5 < z < 1 and have since faded into low luminosity, low surface brightness objects. Such a scenario, which arises naturally if star formation in dwarf galaxies is delayed by pho

Alan Stockton, Susan E. Ridgway

We present the results of longslit and multiaperture spectroscopy of faint galaxies in the field of the z=1.049 quasar 3C212. We show that an apparently aligned optical feature beyond the NW radio lobe has a redshift z=0.928, and a similarly aligned feature just beyond the SE radio lobe has a redshift z=1.053, quite close to that of the quasar. While the NW

Juri Poutanen

Recent high quality broad-band X-ray and gamma-ray observations of Galactic black holes by ASCA, Ginga, RXTE, and CGRO show that the spectra cannot be described by simple thermal Comptonization models (even including a fully relativistic treatment). Multi-component models accounting for Comptonization by thermal and non-thermal electrons, Compton reflection

Varun Sahni, B. S. Sathyaprakash, Sergei F. Shandarin

We construct a set of shape-finders which determine shapes of compact surfaces (iso-density surfaces in galaxy surveys or N-body simulations) without fitting them to ellipsoidal configurations as done earlier. The new indicators arise from simple, geometrical considerations and are derived from fundamental properties of a surface such as its volume, surface

D. Méra, G. Chabrier, R. Schaeffer

We examine the most recent observational constraints arising from i) small-scale and large-scale Galactic dynamical properties, ii) star counts at faint magnitude and iii) microlensing experiments. From these constraints, we determine the halo and disk stellar mass functions and stellar content down to the bottom of the main sequence, which yields the normal

D. Méra, G. Chabrier, R. Schaeffer

We use the calculations derived in a previous paper (Méra, Chabrier and Schaeffer, 1997), based on observational constraints arising from star counts, microlensing experiments and kinematic properties, to determine the amount of dark matter under the form of stellar and sub-stellar objects in the different parts of the Galaxy. This yields the derivation of d

M. Salvati, M. Spada, F. Pacini

The extremely rapid burst of TeV photons from Mkn 421 (15 May 1996) can be reconciled with the standard properties of a relativistic gamma-ray emitting jet (bulk Lorentz factor $\approx$ 10; size $\10^{17}$ cm) if one assumes that the electrons are accelerated in conical shocks with both opening and viewing angles $\approx 1/Γ$. If the injection time and the

R. Morganti, P. Padovani, J. Siebert, A. Cimatti

We present new BeppoSAX LECS, MECS, and PDS observations of five lobe-dominated, broad-line active galactic nuclei selected from the 2 Jy sample of southern radio sources. These include three radio quasars and two broad-line radio galaxies. ROSAT PSPC data, available for all the objects, are also used to better constrain the spectral shape in the soft X-ray

Pavel Kroupa

Recently it was shown that low-mass galaxies containing no dark matter can naturally evolve to dSph-like satellites in a tidal field. Such dSph-like satellites fake total domination by dark matter. If this is correct then it must be possible to assemble appropriate precursors of dSph satellites. The genesis of dwarf galaxies in tidal tails appears to be a li

Ruediger Kneissl, Rashid A. Sunyaev, Simon D. M. White

We report on a 16 ks observation with the ROSAT PSPC centred on the CMB decrement which Jones et al. (1997) report in the direction of the quasar pair PC1643+4631. We do not detect the X-ray emission which would be expected if the decrement were caused by Compton up-scattering of CMB photons by hot gas. Our upper limit on the bolometric X-ray flux within a c

Ch. Spiering

We review the present status of the Baikal Underwater Neutrino Experiment and present results obtained with the various stages of the stepwise increasing detector: NT-36 (1993-95), NT-72 (1995-96) and NT-96 (1996-97). Results cover atmospheric muons, first clear neutrino events, search for neutrinos from WIMP annihilation in the center of the Earth, search f

Lars Bildsten

I review the rotation measurements of accreting neutron stars. Many of the highly magnetic accreting X-ray pulsars have been continuously observed with the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory (CGRO) since April 1991. These observations show that the accretion torque exerted on many disk-fed accreting X-ray p

L. Piro, L. Amati, L. A. Antonelli, R. C. Butler

The gamma-ray burst GB970508 was observed simultaneously by the Gamma Ray Burst Monitor (GRBM) and one of the X-ray Wide Field Cameras (WFC) aboard BeppoSAX. The latter provided a position within 1.9&#39; radius. A series of follow-up observations with the Narrow Field Intruments (NFI) was then performed in a period from 6 hours to 6 days after the main even

M. Boettcher, C. D. Dermer

It has recently been proposed that ultrahigh energy ($\gtrsim 10^{19}$ eV) cosmic rays (UHECRs) are accelerated by the blast waves associated with GRBs. We calculate the observed synchrotron radiation spectrum from protons and energetic leptons formed in the cascades initiated by photopion production, taking into account $γγ$ attenuation at the source. Norma

Yu-Qi Chen, Eric Braaten

We propose a new explanation for the longstanding puzzle of the tiny branching fraction of psi&#39; -> rho pi relative to that for J/psi -> rho pi. In the case of J/psi, we argue that this decay is dominated by a higher Fock state in which the ccbar pair is in a color-octet ^3S_1 state and via annihilate process ccbar -> qqbar. In the case of the psi&#39;, w

J. Tonnison, A. M. Sandorfi, S. Hoblit, A. M. Nathan

A proton spin-polarizability characterizing backward Compton scattering has been extracted from a dispersion analysis of data between 33 and 309 MeV. This backward spin-polarizability, &#34;delta&#34; = 27.1 +/-2.2(stat+sys) +2.8/-2.4(model) in units of 10^-4 fm^4, differs significantly from theoretical estimates which are dominated by pi0 t-channel exchange

Monica Valluri, David Merritt

We use Laskar&#39;s frequency mapping technique to study the dynamics of triaxial galaxies with central density cusps and nuclear black holes. For ensembles of 10^4 orbits, we numerically compute the three fundamental frequencies of the motion, allowing us to map out the Arnold web. We also compute diffusion rates of stochastic orbits in frequency space. The

Piotr Bizoń, Tadeusz Chmaj

We study first order phase transitions in the gravitational collapse of spherically symmetric skyrmions. Static sphaleron solutions are shown to play the role of critical solutions separating black-hole spacetimes from no-black-hole spacetimes. In particular, we find a new type of first order phase transition where subcritical data do not disperse but evolve