October 2000 arXiv papers — page 3

T. Calarco, J. I. Cirac, P. Zoller

We consider a system of particles in an array of microscopic traps, coupled to each other via electrostatic interaction, and pushed by an external state-dependent force. We show how to implement a two-qubit quantum gate between two such particles with a high fidelity.

P. Tenenbaum, R. Helm, L. Keller, T. O. Raubenheimer

We present a new conceptual and optical design for the Next Linear Collider post-linac collimation system. Energy collimation and passive protection against off-energy beams are achieved in a system with large horizontal dispersion and vertical betatron functions. Betatron collimation is performed in a relatively low-beta (FODO-like) lattice in which only th

T. O. Raubenheimer

An electron/positron linear collider with a center-of-mass energy between 0.5 and 1 TeV would be an important complement to the physics program of the LHC in the next decade. The Next Linear Collider (NLC) is being designed by a US collaboration (FNAL, LBNL, LLNL, and SLAC) which is working closely with the Japanese collaboration that is designing the Japane

J. B. Almeida

The present work shows that through a suitable change of variables relativistic dynamics can be mapped to light propagation in a non-homogeneous medium. A particle's trajectory through the modified space-time is thus formally equivalent to a light ray and can be derived from a mechanical equivalent of Fermat's principle. The similarities between ligh

J. A. Sheikh, A. T. Kruppa, N. Rowley

For nuclei with N = Z, the isospin degree of freedom is important and, for deformed systems, rotational bands of different isospin may be expected at low excitation energies. We have investigated, in a simple model space, the influence of the isospin-breaking Coulomb interaction on the degree of chaoticity of these rotational bands. The statistical measures

V. V. Flambaum, J. S. M. Ginges, G. Mititelu

We propose a nuclear mechanism which can induce an atomic electric dipole moment (EDM). Parity and time reversal violating (P,T-odd) nuclear forces generate a mixed P,T-odd nuclear polarizability beta_{ik} (defined by an energy shift U = -beta_{ik} E_{i}H_{k}, E is electric field and H magnetic field). The interaction of atomic electrons with beta_{ik} produ

L. Theussl, R. F. Wagenbrunn, B. Desplanques, W. Plessas

πand ηdecay modes of light baryon resonances are investigated within a chiral quark model whose hyperfine interaction is based on Goldstone-boson exchange. For the decay mechanism a modified version of the 3P0 model is employed. Our primary aim is to provide a further test of the recently proposed Goldstone-boson-exchange constituent quark model. We compare

P. O. Hess, S. Misicu, W. Greiner, W. Scheid

A geometrical model for tri-nuclear molecules is presented. An analytical solution is obtained provided the nuclei, which are taken to be prolately deformed, are connected in line to each other. Furthermore, the tri-nuclear molecule is composed of two heavy and one light cluster, the later sandwiched between the two heavy clusters. A basis is constructed in

S. Misicu, P. O. Hess, A. Sandulescu, W. Greiner

Based on a recent experimental finding which may suggest the existence of a tri-nuclear molecular structure before the cold ternary fragmentation of $^{252}$Cf takes place, we solved the eigenvalue problem of a certain class of vibrations which are very likely to occur in these molecules. These oscillations are the result of the joined action of rotations of

S. Misicu, A. Sandulescu, G. M. Ter-Akopian, W. Greiner

The recent advent of experimental techniques in which the dynamical characteristics of fission fragments are determined more accurately, prompted us to investigate the angular momentum acquired by fragments in a model which describes the cold(neutronless) fission of $^{252}$Cf as the decay of a giant nuclear molecule. The molecular configuration is a consequ

Yu. N. Uzikov

Deuteron breakup processes $p+d\to (NN)_{s,t}+N$ are studied in the kinematics of backward elastic pd-scattering at law relative momenta of the NN-pair $k\sim 0-50 MeV/c$ for initial energies $T_0=0.5-2.5 GeV$ in the framework of the known mechanisms of the $pd\to dp$ process including rescatterings in the initial and final states. A considerable suppression

E. Melby, M. Guttormsen, J. Rekstad, A. Schiller

The primary gamma-ray spectra of 166-Er and 167-Er are deduced from the (3-He,alpha gamma) and (3-He,3-He' gamma) reaction, respectively, enabling a simultaneous extraction of the level density and the gamma-ray strength function. Entropy, temperature and heat capacity are deduced from the level density within the micro-canonical and the canonical ensemb

A. E. Motter, P. S. Letelier

Methods to estimate the Hausdorff dimension of invariant sets of scattering systems are presented. Based on the levels' hierarchical structure of the time delay function, these techniques can be used in systems whose future-invariant-set codimensions are approximately equal to or greater than one. The discussion is illustrated by a numerical example of a

Marcelo O. Magnasco

Computers and routers on the Internet send each other error messages (called ICMP datagrams) to signal conditions such as network congestion or blackouts. While these datagrams are very rare, less than 0.001% of total traffic, they hold very important global information about problems and congestions elsewhere in the Net. A measurement of the flow of such er

Alan Forrest, John Hunton, Johannes Kellendonk

Aperiodic point sets (or tilings) which can be obtained by the method of cut and projection from higher dimensional periodic sets play an important role for the description of quasicrystals. Their topological invariants can be computed using the higher dimensional periodic structure. We report on the results obtained for the cohomology groups of projection p

Paolo Piccione, Daniel Victor Tausk

We consider a {\em Hamiltonian setup} $\sextuple$, where $(\mathcal M,ω)$ is a symplectic manifold, $\mathfrak L$ is a distribution of Lagrangian subspaces in $\mathcal M$, $\mathcal P$ a Lagrangian submanifold of $ \mathcal M$, $H$ is a smooth time dependent Hamiltonian function on $\mathcal M$ and $Γ:[a,b]\to\mathcal M$ is an integral curve of the Hamilton

Palle E. T. Jorgensen, Daniil P. Proskurin, Yurii Samoilenko

We consider an abstract Wick ordering as a family of relations on elements a_i and define *-algebras by these relations. The relations are given by a fixed operator T:h\otimes h --> h \otimes h, where h is one-particle space, and they naturally define both a *-algebra and an inner-product space H_T, <.,.>_T. If a_i^* denotes the adjoint, i.e., <a_iϕ,ψ>_T=<ϕ,

Vinay Deolalikar

In this work, we use the notion of ``symmetry&#39;&#39; of functions for an extension $K/L$ of finite fields to produce extensions of a function field $F/K$ in which almost all places of degree one split completely. Then we introduce the notion of ``quasi-symmetry&#39;&#39; of functions for $K/L$, and demonstrate its use in producing extensions of $F/K$ in w

Hirotaka Kikyo, Saharon Shelah

If T is an model complete theory with the strict order property, then the theory of the models of T with an automorphism has no model companion.

Saharon Shelah

Solecki proved that the group of automorphisms of a countable structure cannot be an uncountable free abelian group. See more in Just, Shelah and Thomas math.LO/0003120 where as a by product we can say something on on uncountable structures. We prove here the following Theorem: If A is a countable model, then Aut(M) cannot be a free uncountable group.

Manfred Droste, Saharon Shelah

An infinite linearly ordered set (S,<=) is called doubly homogeneous if its automorphism group A(S) acts 2-transitively on it. We show that any group G arises as outer automorphism group G cong Out(A(S)) of the automorphism group A(S), for some doubly homogeneous chain (S,<=).

Rüdiger Göbel, Saharon Shelah

If G and X are groups and N is a normal subgroup of X, then the G-closure of N in X is the normal subgroup X^G= bigcap{kerphi|phi:X-> G, with N subseteq kerphi} of X . In particular, 1^G = R_G X is the G-radical of X. Plotkin calls two groups G and H geometrically equivalent, written G H, if for any free group F of finite rank and any normal subgroup N of F

H. Endo, D. Kotschick

Using the existence of certain symplectic submanifolds in symplectic 4-manifolds, we prove an estimate from above for the number of singular fibers with separating vanishing cycles in minimal Lefschetz fibrations over surfaces of positive genus. This estimate is then used to deduce that mapping class groups are not uniformly perfect, and that the map from th

D. Burns, R. Hind

A compact real analytic Riemannian manifold M admits a canonical complexification with plurisubharmonic exhaustion function satisfying the homogeneous complex Monge-Ampere equation, called a Grauert tube. From the point of view of complex analysis, several authors have considered whether a given complex manifold can arise in more than one way from this const

Alexander Rashkovskii

Generalized Lelong numbers of plurisubharmonic functions with respect to plurisubharmonic weights (due to Demailly) are specified for weights with multicircled asymptotics. Explicit formulas for these values are obtained in terms of the directional Lelong numbers of the functions and the Newton diagrams of the weights. An extension of Demailly&#39;s approxim

Juergen Jost, Kang Zuo

We use pluriharmonic maps to study representations of fundamental groups of algebraic manifolds. This approach is functorial in the sense that the restriction of such a map to a fiber of a fibration remains pluriharmonic, and on this basis, we can investigate the relation between the properties of the original representation and what can be inferred by restr

Huijun Fan, Juergen Jost

The present paper contains an interpretation and generalization of Novikov&#39;s theory of Morse type inequalities for 1-forms in terms of Conley&#39;s theory for dynamical systems.

David Kerr, Claudia Pinzari

We define a notion of dynamical pressure at a self-adjoint element for a contractive completely positive self-map of an exact C*-algebra which adopts Voiculescu&#39;s approximation approach to noncommutative entropy and extends the Voiculescu-Brown topological entropy and Neshveyev-Stormer unital-nuclear pressure. A variational inequality bounding the pressu

Erwin Bolthausen, Yvan Velenik

We consider the d-dimensional massless free field localized by a delta-pinning of strength e. We study the asymptotics of the variance of the field, and of the decay-rate of its 2-point function, as e goes to zero, for general Gaussian interactions. Physically speaking, we thus rigorously obtain the critical behavior of the transverse and longitudinal correl

Yasushi Homma

We give a method of decomposing bundle-valued polynomials compatible with the action of the Lie group $Spin(n)$, where important tools are $Spin(n)$-equivariant operators and their spectral decompositions. In particular, the top irreducible component is realized as an intersection of kernels of these operators.

Sheldon Katz

The versal deformation space of a smooth rational curve in a smooth complex threefold is explicitly computed under certain hypotheses. Under an additional hypothesis, the versal deformation space is then shown to be the variety of critical points of a holomorphic function, the superpotential, as predicted by the consideration of D-branes in string theory.

D. Burns, R. Hind

We show, using standard results in length spectrum rigidity and symplectic homology, that if the unit tangent bundles of two compact surfaces of negative curvature are exact symplectomorphic, then the underlying surfaces are isometric, and hence the disk bundles are symplectomorphic smoothly up to the boundaries. Motivated by the work of Eliashberg and Hofer

Eleny-Nicoleta Ionel, Thomas H. Parker

In the symplectic category there is a `connect sum&#39; operation that glues symplectic manifolds by identifying neighborhoods of embedded codimension two submanifolds. This paper establishes a formula for the Gromov-Witten invariants of a symplectic sum Z=X#Y in terms of the relative GW invariants of X and Y. Several applications to enumerative geometry are

Marco Cavaglia, Paulo Vargas Moniz

We present the canonical and quantum cosmological investigation of a spatially flat, four-dimensional Friedmann-Robertson-Walker (FRW) model that is derived from the M-theory effective action obtained originally by Billyard, Coley, Lidsey and Nilsson (BCLN). The analysis makes use of two sets of canonical variables, the Shanmugadhasan gauge invariant canonic

C. Angelantonj, A. Sagnotti

In a classic paper, Fradkin and Tseytlin showed how magnetic deformations can be introduced in open strings. In this contribution we review some recent work on type-I vacua with magnetised branes and describe the role of additional discrete deformations, related to quantised values of the NS-NS antisymmetric tensor B_ab.

P. Dorey, M. Pillin, A. Pocklington, I. Runkel

We discuss the finite-size properties of a simple integrable quantum field theory in 1+1 dimensions with non-trivial boundary conditions. Novel off-critical identities between cylinder partition functions of models with differing boundary conditions are derived.

Tony Gherghetta

We present metric solutions in six and higher dimensions with a bulk cosmological constant, where gravity is localized on a 3-brane. The corrections to four-dimensional gravity from the bulk continuum modes are power-law suppressed. Furthermore, the introduction of a bulk ``hedgehog&#39;&#39; magnetic field leads to a regular geometry, and can localize gravi

Alberto Santambrogio, Daniela Zanon

We compute the one-loop four-point function in {\cal N}=4 supersymmetric Yang-Mills theory with gauge group U(N). We perform the calculation in {\cal N}=1 superspace using the background field method and obtain the complete off-shell contributions to the effective action from planar and non planar supergraphs. In the low-energy approximation the result simpl

Hiroshi Ozaki

An explicit Lorentz covariant formulation of the canonical theory for classical fields is established on a space-like hypersurface. Hamilton&#39;s equations and a Poisson bracket are defined on the space-like hypersurface. The Poisson bracket relations between total momentum and total angular momentum satisfies the Poincar{é} algebra. It is shown that our Po

Renata Kallosh, Thomas Mohaupt, Marina Shmakova

We study supersymmetric domain walls on S_1/Z_2 orbifolds. The supergravity solutions in the bulk are given by the attractor equation associated with Calabi-Yau spaces and have a naked space-time singularity at some |y_s|. We are looking for possibilities to cut off this singularity with the second wall by a stringy mechanism. We use the collapse of the CY c

E852 Collaboration, P. Eugenio

Results are presented on a partial wave analysis of the Omega Eta final state produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0 -> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=

George Sterman

The energy range and quality of strong-interaction data from recent years demand the study of higher orders in perturbative QCD, and of nonperturbative effects. I discuss a selection of recent progress in the theory of QCD at high energy, including examples from perturbative resummation, nonperturbative power corrections and the Regge limit. In each case, te

W. G. Scott

Trimaximal mixing is the mixing hypothesis with maximal symmetry. In trimaximal mixing there remains a still worrying conflict between the large values of $Δm^2$ preferred by the atmospheric fits (possibly supported by the early K2K data) and reactor limits on $ν_e$-mixing. However, the latest solar results do seem to point to energy-independent (ie. `no-sca

M. Eidemuller, M. Jamin

In this work, the charm quark mass is obtained from a QCD sum rule analysis of the charmonium system. In our investigation we include results from nonrelativistic QCD at next-to-next-to-leading order. Using the pole mass scheme, we obtain a value of $M_c=1.70\pm 0.13$ GeV for the charm pole mass. The introduction of a potential-subtracted mass leads to an im

Andreas Nyffeler

Using a chiral Lagrangian we show that strongly interacting models of electroweak symmetry breaking are not in conflict with precision data. Such models, like Technicolor, need not lead to a heavy Higgs-like signal. Furthermore, the allowed values for the low-energy constants in the effective Lagrangian, derived from bounds on the oblique correction paramete

Andreas Nyffeler

We study the properties of rho mesons in nuclear matter by means of QCD sum rules at finite density. For increased sensitivity, we subtract out the vacuum contributions. With the spectral function as estimated in the literature, these subtracted sum rules are found to be not well satisfied. We suppose that Landau singularities from higher resonance states in

O. Philipsen

Various definitions for the QCD Debye mass and its evaluation are reviewed in a non-perturabtive framework for the study of screening of general static sources. While it is possible to perturbatively integrate over scales $\sim T$ and thus construct a 3d effective theory, the softer scales $\sim gT$ and $\sim g^2T$ are strongly coupled for temperatures $\lsi

M. Faber, J. Greensite, S. Olejnik

A long-range effective action is derived for strong-coupling lattice SU(2) gauge theory in D=3 dimensions. It is shown that center vortices emerge as stable saddlepoints of this action.

T. G. Kovács, E. T. Tomboulis

We discuss the recently published numerical computations of the vortex free energy. They dramatically demonstrate that the excitation probability for a sufficiently thick vortex approaches unity at large beta, i.e. that thick vortices `condense&#39; in the vacuum. This is known to imply confinement. An analytical approach for exploring this phenomenon is als

I. -O. Stamatescu, Chr. Weiss

We aim at reducing the uncertainties inherent in the analysis of the topological structure by using scale controlled smoothing and observables independent on the &#34;microscopic&#34; description of the instanton ensemble.

A. A. Slavnov

A chiral invariant effective action for lattice QCD is proposed. Its connection to the multifermion model is established. A possibility of using this action for computer simulations is discussed.

S. Muroya, A. Nakamura, C. Nonaka

Using Wilson fermions, we study SU(2) lattice QCD with the chemical potential at $β=1.6$. The ratio of fermion determinants is evaluated at each Metropolis link update step. We calculate the baryon number density, the Polyakov loops and the pseudoscalar and vector masses on $4^4$ and $4^3\times 8$ lattices. Preliminary data show the pseudoscalar meson become

Ph. de Forcrand, M. D&#39;Elia, M. Pepe

We study the potential between a static center monopole and antimonopole in 4d SU(2) Yang-Mills theory. Using a new numerical method, we show that the &#39;t Hooft loop is a dual order parameter with respect to the Wilson loop, for the deconfinement phase transition. We observe a 3d Ising-like critical behaviour for the dual string tension related to the spa

H. Matsufuru, Y. Nemoto, H. Suganuma, T. T. Takahashi

We study the static three quark potential using lattice QCD simulation. At zero temperature, the three quark potential is extracted from the baryonic Wilson loop and fitted to the phenomenological form, the sum of the Coulomb term, linearly rising term and the constant. We compare two types of the linear term, ``$Y$&#39;&#39; and ``$Δ$&#39;&#39; type, and fi

Ting-Wai Chiu

The Ginsparg-Wilson relation $D γ_5 + γ_5 D = 2 a D R γ_5 D$ with $R = (a γ_5 D)^{2k}$ is discussed. An explicit realization of D is constructed. It is shown that this sequence of topologically-proper lattice Dirac operators tend to a nonlocal operator in the limit $k \to \infty$. This suggests that the locality of a lattice Dirac operator is irrelevant to i

P. Chen, X. Liao, T. Manke

We report on new results for the spectrum of quarkonia using a fully relativistic approach on anisotropic lattices with quark masses in the range from strange to bottom. A fine temporal discretisation also enables us to resolve excitations high above the ground state. In particular we studied the mass dependence and scaling of hybrid states.

B. Alles, M. D&#39;Elia, M. P. Lombardo, M. Pepe

We present preliminary results about topology and several other quantities at non-zero baryon density and finite temperature in full QCD with N_c=2.

Pushan Majumdar, H. S. Sharatchandra

An explicit canonical transformation is constructed to relate the physical subspace of Yang-Mills theory to the phase space of the ADM variables of general relativity. This maps 3+1 dimensional Yang-Mills theory to local evolution of metrics on 3 manifolds.

MILC Collaboration, C. Bernard, T. Burch, T. A. DeGrand

We have been studying effects of dynamical quarks on various hadronic observables, using our recently formulated improvement for staggered fermions. To illustrate improvement, we show that the light hadron spectrum in the quenched approximation gives remarkably good scaling. We highlight three new results: (1) We find no apparent quark loop effects in the Ed

D. Pleiter, QCDSF Collaboration, UKQCD Collaboration

We present results for the light quark masses in lattice QCD with two degenerate flavours of dynamical fermions. We used configurations generated by the UKQCD and QCDSF collaborations at six different combinations of beta and kappa_sea.

Marc Verderi

The BABAR experiment at the PEP-II asymmetric B factory observed its first hadronic events on the 26th of May 1999. We present the progress made so far on the data taking, the BABAR detector performances and the physics analyses.

Sherry Towers

From an analysis of the current world averages of the charged kaon and tau to kaon branching fractions, we derive, within the framework of type II Higgs doublets models such as the Minimal Supersymmetric Extension of the Standard Model, $\tanβ/m_H < 0.21$ GeV$^{-1}$ at a 90% confidence limit.

F. Nannelli, V. S. U. Fazio, Y. Matsuzawa, L. Komitov

Many nematic liquid crystals (NLCs) lack a polar headgroup and thus are not able to form stable monolayers at the air/water (a/w) interface. A way to obtain monomolecular films of these compounds is to incorporate them into host monolayers of amphiphilic molecules. We report a comparative investigation of mixed films of Calix[4]resorcinarene O-octacarboxymet

Seungoh Ryu

The relaxation of polarized spins in a porous medium has been utilized as a probe of its structure. We note that the governing diffusion problem has a close parallel to that of a particle in a box, an elementary Quantum mechanics toy model. Following the spirits of &#34;free electron&#34; model, we use generic properties of the eigen spectrum to understand f

N. E. Bickers, D. J. Scalapino

We describe a new microscopic approach for analyzing interacting electron systems with local moments or, in principle, any local order parameter. We specialize attention to the doped Mott insulator phase of the Hubbard model, where standard weak-coupling perturbation methods fail. A rotationally invariant Stratonovich-Hubbard field is introduced to decouple

Sergio Caracciolo, Andrea Gambassi, Massimiliano Gubinelli, Andrea Pelissetto

We address the problem of the definition of the finite-volume correlation length. First, we study the large-N limit of the N-vector model, and we show the existence of several constraints on the definition if regularity of the finite-size scaling functions and correct anomalous behaviour above the upper critical dimension are required. Then, we study in deta

D. J. J. Farnell, R. F. Bishop, K. A. Gernoth

The coupled cluster method (CCM) is applied to a spin-half model at zero temperature which interpolates between a triangular lattice antiferromagnet (TAF) and a Kagome lattice antiferromagnet (KAF). The strength of the bonds which connect Kagome lattice sites is J, and the strength of the bonds which link the non-Kagome lattice sites to the Kagome lattice si

Christian Beck, Gregory S. Lewis, Harry L. Swinney

We investigate probability density functions of velocity differences at different distances r measured in a Couette-Taylor flow for a range of Reynolds numbers Re. There is good agreement with the predictions of a theoretical model based on non-extensive statistical mechanics (where the entropies are non-additive for independent subsystems). We extract the s

K. Schulte, M. A. James, P. G. Steeneken, G. A. Sawatzky

It has been argued in a recent paper by R. Joynt (R. Joynt, Science 284, p 777 (1999)) that in the case of poorly conducting solids the photoemission spectrum close to the Fermi Energy may be strongly influenced by extrinsic loss processes similar to those occurring in High Resolution Electron Energy Loss Spectroscopy (HR-EELS), thereby obscuring information

C. Riva, F. M. Peeters, K. Varga

A variational calculation of the spin-singlet and spin-triplet state of a negatively charged exciton (trion) confined to a single quantum well and in the presence of a perpendicular magnetic field is presented. We calculated the probability density and the pair correlation function of the singlet and triplet trion states. The dependence of the energy levels

E. I. Rashba

Theory of electrical spin injection from a ferromagnetic (FM) metal into a normal (N) conductor is presented. We show that tunnel contacts (T) can dramatically increase spin injection and solve the problem of the mismatch in the conductivities of a FM metal and a semiconductor microstructure. We also present explicit expressions for the spin-valve resistance

S. Sugai, N. Hayamizu, T. Hosokawa

Raman spectra of La$_{2-x}$Sr$_x$CuO$_4$ are similar to those of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ except for the split two-magnon peaks at the stripe phase and the stronger step-like decrease in the low energy $B_{\rm 2g}$ spectra. The suppressed $B_{\rm 1g}$ spectral region below the two-magnon peak decreases as the carrier density increases, whereas the energ

Yasushi Suto

I critically review a methodology of using clusters of galaxies as cosmological probes. The understanding of the abundances and spatial correlations of dark matter halos has been significantly advanced especially for a last few years. Nevertheless such dark matter halos are not necessarily identical to clusters of galaxies in the universe. This is a quite ob

K. -H. Bohm, S. Matt

(modified for brevity) It is important to determine whether the observed bow shocks in the working surfaces of Herbig-Haro outflows has lead to a destruction of dust grains and consequently to a change in the gas phase metal abundances (say of Fe) in the cooling regions of HH bow shocks. Detailed studies are currently available for only 5 HH outflows (Beck-W

R. J. Brunner, S. G. Djorgovski, R. R. Gal, A. A. Mahabal

Our current understanding of the low surface brightness universe is quite incomplete, not only in the optical, but also in other wavelength regimes. As a demonstration of the type of science which is facilitated by a virtual observatory, we have undertaken a project utilizing both images and catalogs to explore the multi-wavelength, low surface brightness un

R. J. Reynolds, L. M. Haffner

Recently completed H-Alpha surveys of large portions of the sky can be used to create maps of the free-free intensity distribution at high Galactic latitude that are independent of the spectral fits to the CMB data. This provides an opportunity to test the accuracy of the spectral fitting procedures and to search for other sources of Galactic forground conta

P. J. E. Peebles

I review the assumptions and observations that motivate the concept of the extragalactic cosmic background radiation, and the issues of energy accounts and star formation history as a function of galaxy morphological type that figure in the interpretation of the measurements of the extragalactic infrared background.

Mikhail V. Medvedev

The crisis of both cold and collisional dark matter (DM) models is resolved by postulating flavor mixing of DM particles. Flavor-mixed particles segregate in the gravitational field to form dark halos composed of heavy mass eigenstates. Since these particles are mixed in the interaction basis, elastic collisions convert some of heavy eigenstates into light o

Eric J. Lentz, E. Baron, Peter Lundqvist, David Branch

We present spectral analysis of early observations of the Type IIn supernova 1998S using the general non-local thermodynamic equilibrium atmosphere code \tt PHOENIX}. We model both the underlying supernova spectrum and the overlying circumstellar interaction region and produce spectra in good agreement with observations. The early spectra are well fit by lin

E. Baron, David Branch, Peter H. Hauschildt, Alexei V. Filippenko

We have calculated fast direct spectral model fits to two early-time spectra of the Type-II plateau SN 1999em, using the SYNOW synthetic spectrum code. The first is an extremely early blue optical spectrum and the second a combined HST and optical spectrum obtained one week later. Spectroscopically this supernova appears to be a normal Type II and these fits

Rob Fender

I discuss the energetics of synchrotron-emitting outflows, increasingly found to be present in many different classes of X-ray binary systems. It is shown that the outflow is likely to be comparable in power to the integrated X-ray luminosity, traditionally taken to be an indicator of the global mass-transfer rate. This is especially found to be the case in

M. J. L. Turner, J. N. Reeves, T. J. Ponman, M. Arnaud

This paper presents the XMM-Newton first-light observations of the Hickson-16 compact group of galaxies. Groups are possibly the oldest large-scale structures in the Universe, pre-dating clusters of galaxies, and are highly evolved. This group of small galaxies, at a redshift of 0.0132 (or 80 Mpc) is exceptional in the having the highest concentration of sta

E. Ros, J. M. Marcaide, J. C. Guirado, M. A. Perez-Torres

The use of the phase-delay improves substantially the accuracy obtained in VLBI astrometry with respect to the group-delay observable. Recently, Ros et al. (1999) have extended the related phase-connection technique to a triangle of radio sources with relative separations up to 6.8deg (the S5 sources BL1803+784/ QSO1928+738/ BL2007+777). This technique has a

Richard Lieu, Max Bonamente, Jonathan P. D. Mittaz

Various independent ways of constraining key cosmological parameters yielded a consensus range of values which indicates that at the present epoch the bulk of the universe&#39;s baryons is in the form of a warm ($\sim$ 10$^6$ K) gas - a temperature regime which renders them difficult to detect. The discovery of EUV and soft X-ray excess emission from cluster

T. Oosterbroek, D. Barret, M. Guainazzi, E. C. Ford

We have obtained spectral and timing data on GX 3+1 and Ser X-1. Both sources were observed simultaneously with BeppoSAX and RXTE. The RXTE data is used to provide power spectra and colour-colour diagrams in order to constrain the state (and thus track $\dot M$) the sources are in. The BeppoSAX data provide the broad-band spectra. The spectra of both sources

W. Pietsch, T. P. Roberts, M. J. Freyberg, A. M. Read

The high XMM-Newton throughput allows a detailed investigation of the spatial, spectral and variability properties of the extended and point source emission of the starburst galaxy NGC 253 simultaneously. We characterize the brightest sources by their hardness ratios, detect a bright X-ray transient, and show the spectrum and light curve of the brightest poi

Christian Fendt, Detlef Elstner

The evolution of an initially stellar dipole type magnetosphere interacting with an accretion disk is investigated numerically using the ideal MHD ZEUS-3D code in the 2D-axisymmetry option. The simulations last several thousands of Keplerian periods of the inner disk. A Keplerian disk is assumed as a boundary condition prescribing a mass inflow into the coro

J. A. M. Bleeker, R. Willingale, K. van der Heyden, K. Dennerl

We present the first results on the hard X-ray continuum image (up to 15 keV) of the supernova remnant Cas A measured with the EPIC cameras onboard XMM-Newton. The data indicate that the hard X-ray tail, observed previously, that extends to energies above 100 keV does not originate in localised regions, like the bright X-ray knots and filaments or the primar

C. Wolf, K. Meisenheimer, H. -J. Röser, S. V. W. Beckwith

We use a multi-color classification method introduced by Wolf, Meisenheimer & Roeser (2000) to reliably identify stars, galaxies and quasars in the up to 16-dimensional color space provided by the filter set of the Calar Alto Deep Imaging Survey (CADIS). The samples of stars, galaxies and quasars obtained this way have been used for dedicated studies publish

Janusz Gil, Dipanjan Mitra

In this paper we revisit the radio pulsar death line problem within the framework of curvature radiation and/or inverse compton scattering induced vacuum gap model above neutron star polar caps. Our special interest is in the recently detected pulsar PSR J2144-3933 with extremal period 8.5 seconds, which lies far beyond conventional death lines. We argue, th

Albert A. Zijlstra, J. M. Chapman, P. te Lintel Hekkert, L. Likkel

We investigate the development of bipolar outflows during the early post-AGB evolution. A sample of ten OH/IR stars is observed at high angular resolution, including bipolar nebulae (OH231.8+4.2), bright post-AGB stars (HD 101584) and reflection nebulae (e.g. Roberts 22). The IRAS colour--colour diagram separates the sample into different types of objects. O

Torsten A. Ensslin, Gopal-Krishna

A new model for the, so called, `cluster radio relics&#39; is presented (Ensslin & Gopal-Krishna 2000). Fossil radio cocoons, resulting from the former activity of radio galaxies, should contain a low energy relativistic electron population and magnetic fields. Electrons with an age of even up to 2 Gyr can be re-accelerated adiabatically to radio emitting en

R. T. Edwards, M. Bailes

We have discovered two recycled pulsars in relativistic orbits as part of the first high-frequency survey of intermediate Galactic latitudes. PSR J1157-5112 is a 44 ms pulsar and the first recycled pulsar with an ultra-massive (M > 1.14 Mo) white dwarf companion. Millisecond pulsar J1757-5322 is a relativistic circular-orbit system which will coalesce due to

J. D. Vergados

The detection of the theoretically expected dark matter is central to particle physics and cosmology. Current fashionable supersymmetric models provide a natural dark matter candidate which is the lightest supersymmetric particle (LSP). The theoretically obtained event rates are usually very low or even undetectable. So the experimentalists would like to exp

Y. Sofue, J. Koda, K. Kohno, S. K. Okumura

We have performed high-resolution synthesis observations of the 12CO (J=1-0) line emission from the radio lobe edge-on spiral NGC 3079 using a 7-element mm-wave interferometer at Nobeyama, which consisted of the 45-m telescope and 6-element Array. The molecular nuclear disk (NMD) of 750 pc radius is found to be inclined by 20 degrees from the optical disk, a

L. Verozub, E. Kochetov

The analysis of the data from the distant supernovae (A.Riess et al, Astron.J. {\bf 116}, 1009, (1988)) for acceleration of the expending Universe from the viewpoint of the gravitation equations proposed by one of the authors (Phys.Lett. {\bf 156}, 404 (1991)) is given. It is shown that the result from the above data that the deceleration parameter $q_{0}$ i

Yoshiaki SOFUE

We emphasize the use of high-resolution CO line observations to derive central rotation curves of galaxies. We present an example for high-resolution interferometer observations of NGC 3079, and discuss the PV diagram and derived rotation curve. The CO central rotation curves are combined with the outer curves from \ha and HI-line observations to obtain tota

Juan Carlos Vega Beltran, Peter Erwin, John Beckman, Alessandro Pizzella

Recent advances in observational techniques and theoretical modelling of galaxy kinematics allow us to use more than just optical morphology to discern the structure and dynamics of galaxies. Here, we show for three barred galaxies (UGC 10205, NGC 6221 and NGC4340) that both kinematics and photometry are necessary to fully understand the properties of these

M. M. Hedman, D. Barkats, J. O. Gundersen, S. T. Staggs

A ground-based polarimeter, PIQUE, operating at 90 GHz has set a new limit on the magnitude of any polarized anisotropy in the cosmic microwave background. The combination of the scan strategy and full width half maximum beam of 0.235 degrees gives broad window functions with average multipoles, l = 211+294-146 and l = 212+229-135 for the E- and B-mode windo

F. R. Pearce, A. Jenkins, C. S. Frenk, S. D. M. White

We present results of large N-body-hydrodynamic simulations of galaxy formation. Our simulations follow the formation of galaxies in cubic volumes of side 100Mpc, in two versions of the cold dark matter (CDM) cosmogony: the standard, Omega=1 SCDM model and the flat, Omega=0.3 LCDM model. Over 2000 galaxies form in each of these simulations. We examine the ra