May 2000 arXiv papers — page 18

H. Weigel

Within the collective coordinate approach to chiral soliton models we suggest that breaking of SU(3) flavor symmetry mainly resides in the baryon wave-functions while the charge operators maintain a symmetric structure. Sizable symmetry breaking in the wave-functions is required to reproduce the observed spacing in the spectrum of the (1/2)^+ baryons. The ma

S. R. Souza, W. P. Tan, R. Donangelo, C. K. Gelbke

We discuss different aspects which could influence temperatures deduced from experimental isotopic yields in the multifragmentation process. It is shown that fluctuations due to the finite size of the system and distortions due to the decay of hot primary fragments conspire to blur the temperature determination in multifragmentation reactions. These facts su

Peter Arnold, Boris Tomasik

Baym, Blaizot, and Zinn-Justin have recently used the large N approximation to calculate the effect of interactions on the transition temperature of dilute Bose gases. We extend their calculation to next-to-leading-order in 1/N and find a relatively small correction of -26% to the leading-order result. This suggests that the large N approximation works surpr

Alfredo Aranda, Marc Sher

We examine extensions of the MSSM with more than one generation of Higgs bosons. If one assumes that a symmetry eliminates the tree-level FCNC, then the extra scalar bosons do not acquire VEVs, do not couple to fermions and do not mix with the ordinary Higgs bosons; the lightest is absolutely stable. The two lightest neutral scalars, $ϕ_S$, and $ϕ_P$, are de

J. Gaite

There are two general irreversibility theorems for the renormalization group in more than two dimensions: the first one is of entropic nature, while the second one, by Forte and Latorre, relies on the properties of the stress-tensor trace, and has been recently questioned by Osborn and Shore. We start by establishing under what assumptions this second theore

Spencer R. Klein

At heavy ion colliders, two major sources of beam loss are expected to be $e^+e^-$ production, where the $e^-$ is bound to one of the nuclei, and photonuclear excitation and decay via neutron emission. Both processes alter the ions charged to mass ratio by well defined amounts, creating beams of particles with altered magnetic rigidity. These beams will depo

T. Roy Choudhury, T. Padmanabhan, R. Srianand

Analytic derivations of the correlation function and the column density distribution for neutral hydrogen in the IGM are presented, assuming that the non-linear baryonic mass density distribution in the IGM is lognormal. This ansatz was used earlier by Bi & Davidsen (1997) to perform 1D simulations of lines-of-sight and analyse the properties of absorption s

E. T. Akhmedov

In this note $D9$- and anti-$D9$-brane annihilation in type I string theory is probed by a $D1$-brane. We consider the covariant Green-Schwarz or twistor formulation of the probe theory. We expect the theory to be $κ$-invariant after the annihilation is completed. Conditions of the $κ$-invariance of the theory impose constraints on the background tachyon fie

M. Abolfath, Kieran Mullen, H. T. C. Stoof

We apply the theory of elasticity to study the effects of skyrmion mass on lattice dynamics in quantum Hall systems. We find that massive Skyrme lattices behave like a Wigner crystal in the presence of a uniform perpendicular magnetic field. We make a comparison with the microscopic Hartree-Fock results to characterize the mass of quantum Hall skyrmions at $

Annalisa Bossi, Nicoletta Cocco, Sandro Etalle, Sabina Rossi

We propose a modular method for proving termination of general logic programs (i.e., logic programs with negation). It is based on the notion of acceptable programs, but it allows us to prove termination in a truly modular way. We consider programs consisting of a hierarchy of modules and supply a general result for proving termination by dealing with each m

Robert A. Herrmann

Using properties of the nonstandard physical world, a new fundamental derivation for all of the effects of the Special Theory of Relativity is given. This fundamental derivation removes all the contradictions and logical difficulties in the original derivation and leads to the fundamental expressions from which Prokhovnik derives the basic transformations. H

Laurent Bartholdi, Zoran Sunik

We generalize a class of groups defined by Rostislav Grigorchuk to a much larger class of groups, and provide upper and lower bounds for their word growth (they are all of intermediate growth) and period growth (under a small additional condition, they are periodic).

M. Özer, M. O. Taha

It is shown how the relation $ds=cdτ$ between the proper distance $s$ and the proper time $τ$ is obtained in general relativity. A general relation in curved spacetime between $dτ$ and $dt$ is given. This relation reduces to the special relativistic one for flat spacetime.

Matthias Burkardt

It is shown that off-forward parton distributions for $ζ=0$, i.e. where the initial and final state differ only in their transverse momenta, can be interpreted as a simultaneous measurement of the longitudinal momentum and transverse position (impact parameter) of partons in the infinite momentum frame.

C. Briot, E. Ragoucy

We construct a wide class of finite W-algebras as truncations of Yangians. These truncations correspond to algebra homomorphisms and allow to construct the W-algebras as exchange algebras, the R-matrix being the Yangian's one. As an application, we classify all irreducible finite dimensionnal representations of these W-algebras and determine their center

ZEUS Collaboration

A measurement of the proton structure function F_2(x,Q^2) is presented in the kinematic range 0.045 GeV^2 < Q^2 < 0.65 GeV^2 and 6*10^{-7} < x < 1*10^{-3}. The results were obtained using a data sample corresponding to an integrated luminosity of 3.9pb^-1 in e^+p reactions recorded with the ZEUS detector at HERA. Information from a silicon-strip tracking det

V. Elias, A. D. Polosa, M. D. Scadron, N. A. Törnqvist

We explore how chiral-symmetry constraints on weak-interaction matrix elements suggest the existence of an intermediate state sigma in several different weak-interaction processes. Particular attention is directed toward recent evidence for a sigma within three-body nonleptonic weak decays.

Sarkis Frédéric

The present paper have been replaced by the paper: Hartogs-Bochner type theorem in Projective Space (math.CV/0011095) in which we prove the following Hartogs-Bochner type theorem: Let $M$ be a connected $C^2$ hypersurface of $P_n(\mathbb{C})$ ($n\geq 2$) which divides $P_n(\mathbb{C})$ in two connected open sets $Ω_1$ and $Ω_2$. Then there exists $i \in \{1,

S. Tsujikawa

We investigate preheating in a higher-dimensional generalized Kaluza-Klein theory with a quadratic inflaton potential $V(ϕ)=\frac12 m^2ϕ^2$ including metric perturbations explicitly. The system we consider is the multi-field model where there exists a dilaton field $σ$ which corresponds to the scale of compactifications and another scalar field $χ$ coupled t

D. T. Frayer, Ian Smail, R. J. Ivison, N. Z. Scoville

We report the detection of 1.3mm continuum and near-infrared K-band (2.2-micron) emission from the submillimeter galaxy SMM J00266+1708. Although this galaxy is among the brightest sub-mm sources detected in the blank-sky surveys (L~10^{13} L[sun]), SMM J00266+1708 had no reliable optical/near-infrared counter-part. We used sensitive interferometric 1.3mm ob

H. Athar, M. Jezabek, O. Yasuda

Several cosmologically distant astrophysical sources may produce high-energy cosmic neutrinos (E \geq 10^6 GeV) of all flavors above the atmospheric neutrino background. We study the effects of vacuum neutrino mixing in three flavor framework on this cosmic neutrino flux. We also consider the effects of possible mixing between the three active neutrinos and

R. Friedberg, T. D. Lee, W. Q. Zhao

We present a new method to derive low-lying N-dimensional quantum wave functions by quadrature along a single trajectory. The N-dimensional Schroedinger equation is cast into a series of readily integrable first order ordinary differential equations. Our approach resembles the familiar W.K.B. approximation in one dimension, but is designed to explore the cla

Seiya Goto, Hiroyuki Hata

We study the noncommutative U(2) monopole solution at the second order in the noncommutativity parameter θ^{ij}. We solve the BPS equation in noncommutative super Yang-Mills theory to O(θ^2), transform the solution to the commutative description by the Seiberg-Witten (SW) map, and evaluate the eigenvalues of the scalar field. We find that, by tuning the free

Krishna Rajagopal

I review arguments for the existence of a critical point E in the QCD phase diagram as a function of temperature T and baryon chemical potential μ. I describe how heavy ion collision experiments at the SPS and RHIC can discover the tell-tale signatures of such a critical point, thus mapping this region of the QCD phase diagram. I contrast the different ways

Abhee K. Dutt-Mazumder, Ralf Hofmann, Maxim Pospelov

We evaluate the operator product expansion (OPE) for a mixed correlator of the isovector and isoscalar vector currents in the background of the nucleon density with intrinsic isospin asymmetry [i.e. excess of neutrons over protons] and match it with its imaginary part, given by resonances and continuum, via the dispersion relation. The leading density-depend

G. M. D&#39;Ariano, C. Macchiavello, P. Perinotti, M. F. Sacchi

We prove that isotropic squeezing of the phase is equivalent to reversing the arrow of time.

N. Gisin, S. Wolf

After carrying out a protocol for quantum key agreement over a noisy quantum channel, the parties Alice and Bob must process the raw key in order to end up with identical keys about which the adversary has virtually no information. In principle, both classical and quantum protocols can be used for this processing. It is a natural question which type of proto

Diego G. Arbo, Mario A. Castagnino, Fabian H. Gaioli, Sergio Iguri

Brownian motion is modelled by a harmonic oscillator (Brownian particle) interacting with a continuous set of uncoupled harmonic oscillators. The interaction is linear in the coordinates and the momenta. The model has an analytical solution that is used to study the time evolution of the reduced density operator. It is derived in a closed form, in the one-pa

Karl-Heinz Fichtner, Masanori Ohya

Following the previous paper in which quantum teleportation is rig orously discussed with coherent entangled states given by beam splittings, we further discuss two types of models, perfect teleportation model and non-perfect teleportation model, in general scheme. Then the difference among several models, i.e., the perfect models and the non-perfect models,

A. E. Kobryn, M. V. Tokarchuk, Y. A. Humenyuk

The Enskog-Landau kinetic equation is considered to describe non-equilibrium processes of a mixture of charged hard spheres. This equation has been obtained in our previous papers by means of the non-equilibrium statistical operator method. The normal solution of this kinetic equation found in the first approximation using the standard Chapman-Enskog method

W. C. Haxton

The history of the Department of Energy&#39;s Institute for Nuclear Theory, located on the campus of the University of Washington, is reviewed on the occasion of the INT&#39;s tenth anniversary.

M. N. Ovchinnikov

The usable limits of the customary and relaxational filtrational theories are considered. The questions of applicable the locality and local thermodynamical equilibrium principles to depict the nonstationary flows are discussed. The experimental procedures are proposed to determine the filtrational flows relaxation times.

E. N. E. van Dalen, A. E. L. Dieperink, A. Sedrakian, R. G. E. Timmermans

We study the neutrino emissivity of strongly magnetized neutron stars due to the charged and neutral current couplings of neutrinos to baryons in strong magnetic fields. The leading order neutral current process is the one-body neutrino-pair bremsstrahlung, which does not have an analogue in the zero field limit. The leading order charged current reaction is

T. Kojima

We study the 19-vertex model associated with the quantum group $U_q(\hat{sl_2})$ at critical regime $|q|=1$. We give the realizations of the type-I vertex operators in terms of free bosons and free fermions. Using these free field realizations, we give the integral representations for the correlation functions.

Irene I. Bouw, Stefan Wewers

In this paper we study the reduction of Galois covers of curves, from characteristic 0 to characteristic p. The starting point is a is a recent result of Raynaud which gives a criterion for good reduction for covers of the projective line branch at 3 points. Under some condition on the Galois group, we extend this criterion to the case of 4 branch points. Mo

Igor Frenkel, Anton Malkin, Maxim Vybornov

C.M. Ringel defined Hall algebra associated with the category of representations of a quiver of Dynkin type and gave an explicit description of the structure constants of the corresponding Lie algebra. We utilize functorial properties of the Hall algebra to give a simple proof of Ringel&#39;s result, and to generalize it to the case of a quiver of affine typ

Naichung Conan Leung, Shing-Tung Yau, Eric Zaslow

We exhibit a transformation taking special Lagrangian submanifolds of a Calabi-Yau together with local systems to vector bundles over the mirror manifold with connections obeying deformed Hermitian-Yang-Mills equations. That is, the transformation relates supersymmetric A- and B-cycles. In this paper, we assume that the mirror pair are dual torus fibrations

P. Constantin

This work presents an approach to the Navier-Stokes equations that is phrased in unbiased Eulerian coordinates, yet describes objects that have Lagrangian significance: particle paths, their dispersion and diffusion. The commutator between Lagrangian and Eulerian derivatives plays an important role in the Navier-Stokes equations: it contributes a singular pe

Stanley S. Chang

Block and Weinberger show that an arithmetic manifold can be endowed with a positive scalar curvature metric if and only if its $\rationals$-rank exceeds 2. We show in this article that these metrics are never in the same coarse class as the natural metric inherited from the base Lie group. Furthering the coarse $C^\ast$-algebraic methods of Roe, we find a n

Victor Guba, Mark Sapir

In this paper, we continue our study of the class of diagram groups. Simply speaking, a diagram is a labelled plane graph bounded by a pair of paths (the top path and the bottom path). To multiply two diagrams, one simply identifies the top path of one diagram with the bottom path of the other diagram, and removes pairs of &#34;reducible&#34; cells. Each dia

A. Yu. Olshanskii, M. V. Sapir

We construct easy embeddings of relatively free groups (say the free Burnside group, the free solvable group) into finitely presented groups. We introduce a concept of verbal isoperimetric function of a group variety. We prove that if the verbal Dehn function of a relatively free group is bounded by a polynomial then the group can be embedded quasi-isometric

S. C. Power

Let E be an operator algebra on a Hilbert space with finite-dimensional generated C*-algebra. A classification is given of the locally finite algebras and the operator algebras obtained as limits of direct sums of matrix algebras over E with respect to star-extendible homomorphisms. The invariants in the algebraic case consist of an additive semigroup, with

P. Akueson, D. Gurevich

Let $k(S^2_q)$ be the &#34;coordinate ring&#34; of a quantum sphere. We introduce the cotangent module on the quantum sphere as a one-sided $k(S^2_q)$-module and show that there is no Yang-Baxter type operator converting it into a $k(S^2_q)$-bimodule which would be a flatly deformed object w.r.t. its classical counterpart. This implies non-flatness of any co

Olof-Petter OEstlund

In this paper a classification of Reidemeister moves, which is the most refined, is introduced. In particular, this classification distinguishes some $Ω_3$-moves that only differ in how the three strands that are involved in the move are ordered on the knot. To transform knot diagrams of isotopic knots into each other one must in general use $Ω_3$-moves of a

Ulrich Hermisson

The derivations of a left coideal subalgebra B of a Hopf algebra A which are compatible with the comultiplication of A (that is, the covariant first order differential calculi, as defined by Woronowicz, on a quantum homogeneous space) are related to certain right ideals of B. The correspondence is one-to-one if A is faithfully flat as a right B-module. This

Victor Guba, Mark Sapir

We show a rigid connection between two classical objects: the R.Thompson group F and the Dunce hat. A diagram group of a directed 2-complex contains a copy of F if and only if the complex contains a copy of the Dunce hat.

F. A. Schaposnik, P. Suranyi

Following a brief review of known vortex solutions in SU(N) gauge-adjoint Higgs theories we show the existence of a new ``minimal&#39;&#39; vortex solution in SU(3) gauge theory with two adjoint Higgs bosons. At a critical coupling the vortex decouples into two abelian vortices, satisfying Bogomol&#39;nyi type, first order, field equations. The exact value o

Saurya Das, Amit Ghosh, P. Mitra

The statistical entropy of a Schwarzschild black string in five dimensions is obtained by counting the black string states which form a representation of the near-horizon conformal symmetry with a central charge. The statistical entropy of the string agrees with its Bekenstein-Hawking entropy as well as that of the Schwarzschild black hole in four dimensions

Ervig Lapalme, Yvan Saint-Aubin

Probabilities of crossing on same-spin clusters, seen as order parameters, have been introduced recently for the critical 2d Ising model by Langlands, Lewis and Saint-Aubin. We extend Cardy&#39;s ideas, introduced for percolation, to obtain an ordinary differential equation of order 6 for the horizontal crossing probability pih. Due to the identity pih(r)+pi

Masashi Hashimoto

Using Kaluza-Klein technique we show that the singularity of Hawking-Turok type has a fixed point (bolt) contribution to the action in addition to the usual boundary contribution. Interestingly by adding this contribution we can obtain a simple expression for the total action which is feasible for both regular and singular instantons. Our result casts doubt

Katherine A Seaton, M. T. Batchelor

On the basis of the result obtained by applying Baxter&#39;s exact perturbative approach to the dilute A_3 model to give the E_8 mass spectrum, the dilute A_L inversion relation was used to predict the eigenspectra in the L=4 and L=6 cases (corresponding to E_7 and E_6 respectively). In calculating the next-to-leading term in the correlation lengths, or equi

P. Aurenche, C. Balazs, R. D. Ball, T. Binoth

The Les Houches Workshop on Physics at TeV Colliders took place from June 8-18, 1999. One of the three working groups at Les Houches concentrated on QCD issues, both at the Tevatron Collider and at the LHC. Besides the interest in QCD in its own right, QCD dynamics plays an important role in the production mechanisms for any new physics process that might be

R. Demina, S. Keller, M. Krämer, S. Kretzer

We present a status report of a variety of projects related to heavy quark production and parton distributions for the Tevatron Run II.

Vigdor L. Teplitz, Rabindra N. Mohapatra, Fred Olness, Ryszard Stroynowski

We consider laboratory experiments that can detect stable, neutral strongly interacting massive particles (SIMPs). We explore the SIMP annihilation cross section from its minimum value (restricted by cosmological bounds) to the barn range, and vary the mass values from a GeV to a TeV. We also consider the prospects and problems of detecting such particles at

E. Norrbin, T. Sjöstrand

Heavy long-lived quarks, i.e. charm and bottom, are frequently studied both as tests of QCD and as probes for other physics aspects within and beyond the standard model. The long life-time implies that charm and bottom hadrons are formed and observed. This hadronization process cannot be studied in isolation, but depends on the production environment. Within

Utpal Chattopadhyay, Tarek Ibrahim, Pran Nath

A brief review is given of the effects of CP violation on the direct detection of neutralinos in dark matter detectors. We first summarize the current developments using the cancellation mechanism which allows for the existence of large CP violating phases consistent with experimental limits on the electron and on the neutron electric dipole moments in a bro

Kenji Morita, Shin Muroya, Hiroki Nakamura, Chiho Nonaka

We numerically calculate two-particle correlation functions of CERN-SPS 158 A GeV Pb+Pb central collisions based on a (3+1)-dimensional relativistic hydrodynamics with a first order phase transition. We analyze the pair momentum dependence of pion source sizes extracted from the Yano-Koonin-Podgoretski\uı (YKP) parametrization which is expected to give the s

J. Arafune, T. Yoshida, S. Nakamura, K. Ogure

We have re-analyzed the results of various experiments which were not originally interested as searches for the Q-ball or the Fermi-ball. Based on these analyses, in addition to the available data on Q-balls, we obtained rather stringent bounds on flux, mass and typical energy scale of Q-balls as well as Fermi-balls. In case these nontopological solitons are

Masuho Oda, Kazunori Nishimura, Muneyuki Ishida, Shin Ishida

The spectra and branching ratios of the weak semi-leptonic B meson decays to the first excited D mesons are predicted, taking into account the confined effects of quarks using the covariant oscillator quark model (COQM). In the COQM the same relation between general weak transition form factors as that in HQET is derived, and the concrete form of the Isgur-W

Duane A. Dicus, Wayne W. Repko, Vigdor L. Teplitz

Recently, Barger {\em et al.} computed energy losses into Kaluza Klein modes from astrophysical plasmas in the approximation of zero density for the plasmas. We extend their work by considering the effects of finite density for two plasmon processes. Our results show that, for fixed temperature, the energy loss rate per cm$^3$ is constant up to some critical

Ilya Narsky

Expected coverage and expected length of 90% upper and lower limit and 68.27% central intervals are plotted as functions of the true signal for various values of expected background. Results for several objective priors are shown, and formulas for calculation of confidence intervals are obtained. For comparison, expected coverage and length of frequentist in

M. N. Achasov, S. E. Baru, K. I. Beloborodov, A. V. Berdyugin

In the SND experiment at VEPP-2M $e^+e^-$ collider the $ϕ(1020)\toπ^0π^0γ$ decay was studied and its branching ratio was measured: $B(ϕ\toπ^0π^0γ)=(1.221\pm 0.098\pm0.061)\cdot10^{-4}$. It was shown, that $f_0(980)γ$ intermediate state dominates in this decay and the $f_0(980)$-meson parameters were obtained.

C. J. de Matos, M. Tajmar

The theory of General Relativity explaines the advance of Mercury perihelion using space curvature and the Schwartzschild metric. We demonstrate that this phenomena can also be interpreted due to the cogravitational field produced by the apparent motion of the Sun around Mercury giving exactly the same estimate as derived from the Schwartzschild metric in ge

Alberto Garcia, Alfredo Macias, Dirk Puetzfeld, Jose Socorro

We study plane-fronted electrovacuum waves in metric-affine gravity theories (MAG) with cosmological constant. Their field strengths are, on the gravitational side, curvature $R_α{}^β$, nonmetricity $Q_{αβ}$, torsion $T^α$ and, on the matter side, the electromagnetic field strength $F$. Our starting point is the work by Ozsváth, Robinson, and Rózga on type N

Hiroshi Umetsu

The analytic proof of mode stability of the Kerr black hole was provided by Whiting. In his proof, the construction of a conserved quantity for unstable mode was crucial. We extend the method of the analysis for the Kerr-de Sitter geometry. The perturbation equations of massless fields in the Kerr-de Sitter geometry can be transformed into Heun&#39;s equatio

Ian Horrock, Ulrike Sattler, Stephan Tobies

While there has been a great deal of work on the development of reasoning algorithms for expressive description logics, in most cases only Tbox reasoning is considered. In this paper we present an algorithm for combined Tbox and Abox reasoning in the SHIQ description logic. This algorithm is of particular interest as it can be used to decide the problem of (

G. S. Lozano, M. V. Manias, E. F. Moreno

We study the properties of the Ginzburg-Laundau model in the self-dual point for a two-dimensional finite system . By a numerical calculation we analyze the solutions of the Euler-Lagrange equations for a cylindrically symmetric ansatz. We also study the self-dual equations for this case. We find that the minimal energy configurations are not given by the Bo

Alexei V. Tkachenko

We present a new approach to far-from-equilibrium statistical mechanics, based on the concept of generalized entropy, which is a microscopically-defined generalization of Onsager-Machlup functional. In the case when a set of slow (adiabatic) variables can be chosen, our formalism yields a general form of the macroscopic evolution law (Generalized Langevin Eq

Paul V. Quinn, Daniel C. Hong

We investigate the liquid-solid transition of two dimensional hard spheres in the presence of gravity. We determine the transition temperature and the fraction of particles in the solid regime as a function of temperature via Even-Driven molecular dynamics simulations and compare them with the theoretical predictions. We then examine the configurational stat

Ayan Guha, N. Khare, A. K. Raychaudhuri, C. N. R Rao

In this letter we report that the current induced destabilization of the charge ordered (CO) state in a rare-earth manganite gives rise to regions with ferromagnetic correlation. We did this experiment by measurement of the I-V curves in single crystal of the CO system Pr$_{0.63}$Ca$_{0.37}$MnO$_{3}$ and simultanously measuring the magnetization of the curre

M. Kubota, Y. Oohara, H. Yoshizawa, H. Fujioka

The charge ordering in the bilayer manganite system La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7}$ with $0.30 \le x \le 0.50$ has been studied by neutron diffraction. The charge order is characterized by the propagation vector parallel to the [1 0 0] direction (MnO$_2$ direction), but the correlation length is short-ranged and extremely anisotropic, being $\sim 0.02a

L. González MacDowell, M. Mueller, C. Vega, K. Binder

We present an application of Wertheim&#39;s Thermodynamic Perturbation Theory (TPT1) to a simple coarse grained model made of flexibly bonded Lennard-Jones monomers. We use both the Reference Hyper-Netted-Chain (RHNC) and Mean Spherical approximation (MSA) integral equation theories to describe the properties of the reference fluid. The equation of state, th

C. Bernhard, T. Holden, A. Golnik, C. T. Lin

The far-infrared c-axis conductivity of flux-grown Y$_{1-x}$Pr$_{x}$Ba$_{2}$Cu$_{3}$O$_{7}$ single crystals with 0.2$\leq $x$\leq $0.5 has been studied by sepectral ellipsometry. We find that the c-axis response exhibits spectral features similar to deoxygenated underdoped YBa$_{2}$Cu$_{3}$O$_{7-δ}$, i.e., a pseudogap develops in the normal state, the phonon

Arno Hartmann, Yann Ducommun, Eli Kapon, Ulrich Hohenester

We investigate experimentally and theoretically few-particle effects in the optical spectra of single quantum dots (QDs). Photo-depletion of the QD together with the slow hopping transport of impurity-bound electrons back to the QD are employed to efficiently control the number of electrons present in the QD. By investigating structurally identical QDs, we s

W. Belzig, Arne Brataas, Yu. V. Nazarov, Gerrit E. W. Bauer

The electron transport though ferromagnetic metal-superconducting hybrid devices is considered in the non-equilibrium Green&#39;s function formalism in the quasiclassical approximation. Attention if focused on the limit in which the exchange splitting in the ferromagnet is much larger than the superconducting energy gap. Transport properties are then governe

K. Dharamvir, Shuchi, V. K. Jindal

Nano-diameter tubules made of folded graphitic sheets have drawn the attention of physicists ever since the advent of fullerene research. These are interesting because of their conductivity (depends upon chirality) as well as their mechanical properties. Bunches of such tubes, single-walled and each of same diameter (~14A), have been produced in the laborato

D. J. Priour, M. P. Gelfand, S. L. Sondhi

We study a one-dimensional chain of corner-sharing triangles with antiferromagnetic Ising interactions along its bonds. Classically, this system is highly frustrated with an extensive entropy at T = 0 and exponentially decaying spin correlations. We show that the introduction of a quantum dynmamics via a transverse magnetic field removes the entropy and open

Zhen Ye, Emile Hoskinson

Multiple scattering of waves leads to many peculiar phenomena such as complete band gaps in periodic structures and wave localization in disordered media. Within a band gap excitations are evanescent; when localized they remain confined in space until dissipated. Here we report acoustic band gap and localization in a 2D system of air-cylinders in water. Exac

Eric A. Lufkin, Craig L. Sarazin, Raymond E. White, III

We analyze two time-dependent cluster cooling flow models in spherical symmetry. The first assumes that the intracluster gas resides in a static external potential, and includes the effects of optically thin radiative cooling and mass deposition. This corresponds to previous steady-state cooling flow models calculated by White & Sarazin (1987). Detailed agre

Deidre A. Hunter, Sally D. Hunsberger, Erin W. Roye

We examine the observational consequences of the two possible origins for irregular galaxies: formation from collapse of a primordial cloud of gas early in the age of the Universe, and formation from tidal tails in an interaction that could have occured any time in the history of the Universe. Because the formation from tidal tails could have occurred a long

N. Mirabal, J. P. Halpern, M. Eracleous, R. H. Becker

The EGRET source 3EG J1835+5918 is the brightest and most accurately positioned of the as-yet unidentified high-energy gamma-ray sources at high Galactic latitude (l,b=89,25). We present a multiwavelength study of the region around it, including X-ray, radio, and optical imaging surveys, as well as optical spectroscopic classification of most of the active o

D. A. Schwartz, H. L. Marshall, J. E. J. Lovell, B. G. Piner

The quasar PKS 0637-753, the first celestial X-ray target of the Chandra X-ray Observatory, has revealed asymmetric X-ray structure extending from 3 to 12 arcsec west of the quasar, coincident with the inner portion of the jet previously detected in a 4.8 GHz radio image (Tingay et al. 1998). At a redshift of z=0.651, the jet is the largest (~100 kpc) and mo

H. I. Teplitz, M. A. Malkan, C. C. Steidel, I. S. McLean

Measurements of [OIII] emission in Lyman Break galaxies (LBGs) at z>3 are presented. Four galaxies were observed with narrow-band filters using the Near-IR Camera on the Keck I 10-m telescope. A fifth galaxy was observed spectroscopically during the commissioning of NIRSPEC, the new infrared spectrometer on Keck II. The emission-line spectrum is used to plac

Re&#39;em Sari, Ann A. Esin

We consider the effects of inverse Compton scattering of synchrotron photons from relativistic electrons in GRB afterglows. We compute the spectrum of the inverse Compton emission and find that it can dominate the total cooling rate of the afterglow for several months or even years after the initial explosion. We demonstrate that the presence of strong inver

Matthew Malkan

The long-awaited promise of studying high-redshift galaxies at long wavelengths has been partially eclipsed by progress at optical wavelengths, mostly because of the number of available pixels. It is nonetheless essential to study optically selected high-redshift galaxies at wavelengths longward of 1\mic, for several reasons. One of the indications from such

S. E. Boggs, P. Jean

The development of germanium Compton telescopes for nuclear gamma-ray astrophysics (~0.2-20 MeV) requires new event reconstruction techniques to accurately determine the initial direction and energy of photon events, as well as to consistently reject background events. This paper describes techniques for event reconstruction, accounting for realistic instrum

Thommy I. Larsen, Jesper Sommer-Larsen, Bernard E. J. Pagel

A numerical double burst model of the chemical evolution of gas-rich dwarf galaxies has been developed. The model is fitted to a sample of N/O, O/H, Y and gas fraction observations, where N/O and O/H are the relative abundances by number of nitrogen to oxygen and oxygen to hydrogen, respectively. Y is the abundance by mass of helium. Closed models as well as

Simon F. Portegies Zwart, Stephen L. W. McMillan, Piet Hut, Junichiro Makino

The evolution of star clusters is studied using N-body simulations in which the evolution of single stars and binaries are taken self-consistently into account. Initial conditions are chosen to represent relatively young Galactic open clusters, such as the Pleiades, Praesepe and the Hyades. The calculations include a realistic mass function, primordial binar

W. Zheng, Z. I. Tsvetanov, D. P. Schneider, X. Fan

We report the discovery of five quasars with redshifts of 4.67 - 5.27 and z&#39;-band magnitudes of 19.5-20.7 M_B ~ -27. All were originally selected as distant quasar candidates in optical/near-infrared photometry from the Sloan Digital Sky Survey (SDSS), and most were confirmed as probable high-redshift quasars by supplementing the SDSS data with J and K m

Michael L. Norman, Tom Abel, Greg Bryan

We discuss the results of recent 3D simulations of first structure formation in relationship to the formation of the first stars. On the basis of a new, high-resolution AMR simulation (spatial dynamic range = 30,000,000), we conclude that the first stars are likely to be massive.

Edward P. J. van den Heuvel, Simon F. Portegies Zwart, Dipankar Bhattacharya, Lex Kaper

The recent finding by Chevalier & Ilovaisky (1998) that OB-supergiant X-ray binaries have relatively large runaway velocities whereas Be/X-ray binaries have low runaway velocities, provides confirmation of the current models for the formation of these two types of systems. These predict a difference in runaway velocity of an order of magnitude. This differen

Rosalba Perna, Tiziana Di Matteo

Current estimates of number counts of radio sources in the frequency range where the most sensitive Cosmic Microwave Background (CMB) experiments are carried out significantly under-represent sources with strongly inverted spectra. Hot accretion flows around supermassive black holes in the nuclei of nearby galaxies are expected to produce inverted radio spec

D. M. Elmegreen, B. G. Elmegreen, F. R. Chromey, M. S. Fine

The giant elliptical galaxy M86 in Virgo has a ~28 kpc long dust trail inside its optical halo that points toward the nucleated dwarf elliptical galaxy, VCC 882. The trail seems to be stripped material from the dwarf. Extinction measurements suggest that the ratio of the total gas mass in the trail to the blue luminosity of the dwarf is about unity, which is

C. S. Crawford, A. C. Fabian, P. Gandhi, R. J. Wilman

We present observations of a sample of optically-faint, hard X-ray sources of the kind likely to be responsible for much of the hard X-ray background. We confirm that such sources are easily detected in the near-infrared, and find that they have a featureless continuum suggesting that the active nucleus is heavily obscured. The infrared colours of the majori

R. Drimmel

Emission profiles of the Galactic plane in K and at $240\micron$ are presented, and features associated with the tangents of the spiral arms are identified. In the K band, which traces stellar emission and suffers little from absorbtion, features associated with the arm tangents indicate that a two-armed logarithmic spiral dominates the nonaxisymmetric struc

Yu. N. Parijskij, W. M. Goss, A. I. Kopylov, N. S. Soboleva

Powerful radio galaxies belong to the population of massive stellar systems that can be picked at high redshifts. With measured redshift, morphology and age determination these objects can help greatly in understanding of the way of formation and evolution of giant elliptical galaxies with massive Black Holes in the Early Universe. We presents some recent re

J. Greiner

This catalog comprises an up-to-date (December 1999) list of luminous (>10^36 erg/s), binary supersoft X-ray sources. This electronic version (including the accompannying Web-pages) supersedes the printed version of Greiner (1996).

John M. Carpenter, Mark H. Heyer, Ronald L. Snell

We analyze the embedded stellar content in the vicinity of the W3/W4/W5 HII regions using the FCRAO Outer Galaxy 12CO(J=1-0) Survey, the IRAS Point Source Catalog, published radio continuum surveys, and new near-infrared and molecular line observations. Thirty-four IRAS Point Sources are identified that have far-infrared colors characteristic of embedded sta

Pojmanski, G

Results of the first two years of observations using the All Sky Automated Survey prototype camera are presented. More than 140 000 stars in 50 Selected Fields covering 300 sq. degrees were monitored each clear night in the I-band resulting in the ASAS Photometric I-band Catalog containing over 50 x 10^6 individual measurements. Nightly monitoring over 100 s

Chung-Pei Ma, J. N. Fry

An analytical understanding of the strongly nonlinear regime of gravitational collapse has been difficult to achieve. The only insight has been the stable clustering hypothesis, which assumes that the number of neighbors for objects averaged over small length scales is constant in time. Our recently proposed analytic halo model for N-point correlation functi