December 2002 arXiv papers — page 10

E. Harikumar, Indrajit Mitra, H. S. Sharatchandra

It is shown that the SO(3) gauge field configurations can be completely characterised by certain gauge invariant vector fields. The singularities of these vector fields describe the topological aspects of the gauge field configurations. The topological (or monopole) charge is expressed in terms of an Abelian vector potential.

Wojciech Krolikowski

Let us imagine that there is an overall quantum theory (not necessarily recognized yet) of matter and energy ({\it i.e.}, of elementary fermions and bosons) interacting with the physical spacetime (treated on a quantum level). Since states of quantum spacetime are so far not observed directly, they ought to be projected out from the overall Hilbert space (mu

Yuri V. Kovchegov, D. T. Son

We find the temperature of the phase transition in the (2+1)d Georgi-Glashow model. The critical temperature is shown to depend on the gauge coupling and on the ratio of Higgs and gauge boson masses. In the BPS limit of light Higgs the previous result by Dunne, Kogan, Kovner, and Tekin is reproduced.

Yi-shi Duan, Peng-ming Zhang

Based on the decomposition of SU(2) gauge field, we derive a generalization of the decomposition theory for the SU(N) gauge field. We thus obtain the invariant electro-magnetic tensors of SU(N) groups and the extended Wu-Yang potentials. The sourceless solutions are also discussed.

Peter Ouyang

We study excited spherical branes (``giant gravitons'') in $AdS \times S$ spacetimes with background flux. For large excitation, these branes may be treated semiclassically. We compute their spectra using Bohr-Sommerfeld quantization and use the AdS/CFT correspondence to relate them to anomalous dimensions in the dual field theory at strong coupling,

M. Botta Cantcheff

We obtain a (Abelian) two form field as a connection on a flat space-time and its corresponding field strength is canonically constructed.

K. Hamaguchi

Leptogenesis in supersymmetric model is discussed comprehensively and in detail. In the first half, we discuss several leptogenesis mechanisms by the decay of heavy right-handed neutrino, which include the standard thermal leptogenesis, leptogenesis via inflaton decay, and leptogenesis from the coherent oscillation of the right-handed sneutrino. In the secon

A. Delfino, J. B. da Silva, M. Malheiro, M. Chiapparini

Recent studies show that for central collisions the rising of the incident energy from AGS to RHIC decreases the value of the chemical potential in the Hadron-QGP phase diagram. Thus, the formation of QGP at RHIC energies in central collisions may be expected to occur at very small values of the chemical potential. Using many different relativistic mean-fiel

Alessandro Bacchetta, Marco Radici

We reconsider the option of extracting the transversity distribution by using interference fragmentation functions into two leading hadrons inside the same current jet. To this end, we perform a new study of two-hadron fragmentation functions. We derive new positivity bounds on them. We expand the hadron pair system in relative partial waves, so that we can

P. A. Baikov, K. G. Chetyrkin, J. H. Kühn

Recently computed terms of orders O(α_s^4 n_f^2) in the perturbative series for the tau decay rate, and similar (new) strange quark mass corrections, are used to discuss the validity of various optimization schemes. The results are then employed to arrive at improved predictions for the complete terms order O(α_s^4) and O(α_s^5) in the massless limit as well

G. Corcella, A. H. Hoang

A detailed compilation of uncertainties in the MSbar bottom quark mass m_b(m_b) obtained from low-n spectral sum rules at order alpha_s^2 is given including charm mass effects and secondary b production. The experimental continuum region above 11.1 GeV is treated conservatively. An inconsistency of the PDG averages for the electronic partial widths of Upsilo

B. O. Kerbikov

We have reexamined the problem of $n-\bar n$ oscillations for ultra-cold neutrons (UCN) confined within a trap. We have shown that the growth of the $\bar n$ component with time is to a decent accuracy given by $P(\bar n)= ε^2_{n\bar n} t_Lt,$ where $ε_{n\bar n}$ is the mixing parameter, $t_L\sim 1 $ sec in the neutron propagation time between subsequent col

Dubravko Klabucar, Dalibor Kekez

We review briefly some of the successes of Schwinger-Dyson (SD) approach to the physics of quarks and hadrons, primarily light pseudoscalar mesons including eta and eta'. The main purpose of this paper is to point out that SD results on eta and eta' mesons can be formulated and given also in the two-mixing-angle scheme.

Dalibor Kekez, Dubravko Klabucar

It is reviewed pedagogically how a very successful description of the eta-eta' mass matrix can be achieved in the consistently coupled Schwinger-Dyson and Bethe-Salpeter approach in spite of the limitations of the ladder approximation. This description is in agreement with both phenomenology and lattice results.

G. L. Kotkin, V. G. Serbo

For the $e^+ e^- \to e^+ e^- γ$ process at colliding beams, macroscopically large impact parameters give an essential contribution to the standard cross section. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard calculations have to be essentially modify. In the present paper such a beam

S. B. Gerasimov

The idea of quark-hadron duality is developed and applied to integral sum rules for the photoexcitation of meson resonances. Some applications of the presented approach in the light and heavy quark sectors are made, and the role of the scalar diquark cluster degrees of freedom in the radiative formation of light scalar mesons is discussed.

L. F. Babichev, A. A. Bukach, V. I. Kuvshinov, V. A. Shaparau

We use the generalized squeezed state description in the framework of the Ginzburg-Landau theory. Multiplicity distributions of the squeezed states are studied at second-order phase transition at different squeeze factors. It is shown that the normalized factorial moments exhibit a specific behaviour as functions of the resolution scale. We obtain the values

Lin Li, Xiangyao Wu, Tao Huang

We analyze the B->KK decays with the soft-gluon corrections by using the QCD light-cone sum rules (LCSR). Although QCD factorization approach calculates the leading order factorization parts and the radiative corrections from hard- gluon exchanges at $α_{s}$ order, it is worthwhile to estimate the nonfactorizable soft-gluon contributions from all the tree an

Masako Bando, Midori Obara

Under the assumption of symmetric four zero texture for fermion mass matrices in SO(10) model, the neutrino Dirc mass matrix is derived from the up-quark mass matrix. By adjusting two scales of the Majorana mass sector, we can derive observed neutrino two large mixing angles very naturally. It is indeed remarkable that all the masses and mixings of neutrinos

K. S. Babu, Jogesh C. Pati

The Extended Supersymmetric Standard Model (ESSM), motivated on several grounds, introduces two vector-like families [16+ 16-bar of SO(10)] with masses of order one TeV. In an earlier work, a successful pattern for fermion masses and mixings (to be called pattern I) has been proposed within a unified SO(10)-framework, based on MSSM, which makes seven predict

Nathan Salwen

Several issues in the modal approach to quantum field theory are discussed. Within the formalism of spherical field theory, differential renormalization is presented and shown to result in a finite number of renormalization parameters. Computations of the massless Thirring model in 1+1 dimensions are presented using this approach. Diagonalization techniques

Michael Creutz

I explore computer simulations of the dynamics of small multi-fermion lattice systems. The method is more general, but I concentrate on Hubbard type models where the fermions hop between a small number of connected sites. I use the natural mapping of fermion occupation numbers onto computer bits. Signs from fermion interchange are reduced to bit counting. Th

A. H. Mahmood

We measure the primary lepton momentum spectrum in B-bar to X l nu decays, for p_l > 1.5 GeV/c in the B rest frame. From this, we calculate various moments of the spectrum. In particular, we find R_0 = [int(E_l>1.7) (dGam/dE_sl)*dE_l] / [int(E_l>1.5) (dGam/dE_sl)*dE_l] = 0.6187 +/- 0.0014_stat +/- 0.0016_sys and R_1 = [int(E_l>1.5) E_l(dGam/dE_sl)*dE_l] / [i

Ulrich F. Katz

Recent results on searches for new particles at the electron-proton collider HERA are reported. Based on roughly 100pb-1 of e^+p data and 16pb-1 of e^-p data per experiment, taken in the years 1994-2000, the H1 and ZEUS collaborations have derived new exclusion limits for the direct production of excited fermion states and leptoquarks. The latter are searche

Suguru Shimizu, for KEK-E470 Collaboration

The radiative decay $K^+ \to π^+ π^0 γ$ ($K_{π2 γ}$) has been measured with stopped positive kaons. A $K_{π2 γ}$ sample containing 4k events was analyzed, and the $K_{π2 γ}$ branching ratio of the direct photon emission process was determined to be $[6.1\pm2.5({\rm stat})\pm1.9({\rm syst})]\times 10^{-6}$. No interference pattern with internal bremsstrahlung

G. L. Comer, R. Joynt

General relativistic superfluid neutron stars have a significantly more intricate dynamics than their ordinary fluid counterparts. Superfluidity allows different superfluid (and superconducting) species of particles to have independent fluid flows, a consequence of which is that the fluid equations of motion contain as many fluid element velocities as superf

Roberto Giambo', Fabio Giannoni, Giulio Magli, Paolo Piccione

A theorem, giving necessary and sufficient condition for naked singularity formation in spherically symmetric non static spacetimes under hypotheses of physical acceptability, is formulated and proved. The theorem relates existence of singular null geodesics to existence of regular curves which are super-solutions of the radial null geodesic equation, and al

Yu. N. Obukhov, J. G. Pereira

The teleparallel gravity theory, treated physically as a gauge theory of translations, naturally represents a particular case of the most general gauge-theoretic model based on the general affine group of spacetime. On the other hand, geometrically, the Weitzenboeck spacetime of distant parallelism is a particular case of the general metric-affine spacetime

Ralf Laemmel, Joost Visser

In previous work, we introduced the notion of functional strategies: first-class generic functions that can traverse terms of any type while mixing uniform and type-specific behaviour. Functional strategies transpose the notion of term rewriting strategies (with coverage of traversal) to the functional programming paradigm. Meanwhile, a number of Haskell-bas

Chiu Fan Lee, Neil F. Johnson

We explore the possibility that physical phenomena arising from interacting multi-particle systems, can be usefully interpreted in terms of multi-player games. We show how non-cooperative phenomena can emerge from Ising Hamiltonians, even though the individual spins behave cooperatively. Our findings establish a mapping between two fundamental models from co

P. -E. Berche, C. Chatelain, B. Berche, W. Janke

In this report we give an overview on recent results obtained from extensive Monte Carlo (MC) computer simulations of the 3D 2-state (Ising) and 4-state Potts models with bond-dilution. The motivation to study the 4-state Potts model derives from the fact that, in the pure case, this model is known to exhibit a fairly strong first-order transition, such that

Gabriele Migliorini, Vakhtang G. Rostiashvili, Thomas A. Vilgis

The Langevin dynamics of a self - interacting chain embedded in a quenched random medium is investigated by making use of the generating functional method and one - loop (Hartree) approximation. We have shown how this intrinsic disorder causes different dynamical regimes. Namely, within the Rouse characteristic time interval the anomalous diffusion shows up.

Damián H. Zanette, Marcelo A. Montemurro

We investigate the origin of Zipf's law for words in written texts by means of a stochastic dynamical model for text generation. The model incorporates both features related to the general structure of languages and memory effects inherent to the production of long coherent messages in the communication process. It is shown that the multiplicative dynami

Ashok Sethia, Eric R. Bittner, Fumio Hirata

The behavior of an excess electron in a one, two and three dimensional classical liquid has been studied with the aid of Chandler, Singh and Richardson (CSR) theory [J. Chem. Phys. {\bf 81} 1975 (1984)] . The size or dispersion of the wavepacket associated with the solvated electron is very sensitive to the interaction between the electron and fluid atoms, a

A. V. Galaktionov, D. S. Golubev, A. D. Zaikin

We analyze current fluctuations in mesoscopic coherent conductors in the presence of electron-electron interactions. In a wide range of parameters we obtain explicit universal dependencies of the current noise on temperature, voltage and frequency. We demonstrate that Coulomb interaction decreases the Nyquist noise. In this case the interaction correction to

G. Y. Chitov, C. Bourbonnais

We apply the standard Wilson-Kadanoff (WK) momentum-space Renormalization Group (RG) scheme for the g-ology model of one-dimensional fermions. By explicitly carrying out calculations at the two-loop level, we show how the RG flow equations can be derived from the summation of the cascades of contractions generated by the effective action's mode eliminati

J. M. Elzerman, R. Hanson, J. S. Greidanus, L. H. Willems van Beveren

We report on the realization of a few-electron double quantum dot defined in a two-dimensional electron gas by means of surface gates on top of a GaAs/AlGaAs heterostructure. Two quantum point contacts (QPCs) are placed in the vicinity of the double quantum dot and serve as charge detectors. These enable determination of the number of conduction electrons on

M. S. Shell, P. G. Debenedetti, E. La Nave, F. Sciortino

Using the inherent structure formalism originally proposed by Stillinger and Weber [Phys. Rev. A 25, 978 (1982)], we generalize the thermodynamics of an energy landscape that has an ideal glass transition and derive the consequences for its equation of state. In doing so, we identify a separation of configurational and vibrational contributions to the pressu

Richard Metzler

This dissertation highlights connections between the fields of neural networks, game theory and time series generation. The concept of antipredictability is explained, and the properties of time series that are antipredictable for several prototypical prediction algorithms (neural networks, Boolean funtions etc.) are studied. The Minority Game provides a fra

Toshiaki Iitaka, Toshikazu Ebisuzaki

We introduce an efficient and numerically stable method for calculating linear response functions $χ(\vec{q},ω)$ of quantum systems at finite temperatures. The method is a combination of numerical solution of the time-dependent Schroedinger equation, random vector representation of trace, and Chebyshev polynomial expansion of Boltzmann operator. This method

M. A. Boselli, I. C. da Cunha Lima, A. Ghazali

The magnetic order resulting from an indirect exchange between magnetic moments provided by spin-polarized hole gas in the metallic phase of a GaMnAs double layer structure is studied via Monte Carlo simulation. The coupling mechanism involves a perturbative calculation in second order of the interaction between the magnetic moments and carriers (holes). We

Hendry Izaac elim, Jianying Ouyang, Jun He, Suat Hong Goh

By using nanosecond laser pulses at 532-nm wavelength, we have studied the nonlinear optical properties of composites which consist of mono-functional 1,2-dihydro-1,2-methanofullerene[60]-61-carboxylic acid (FCA) and poly(styrene-co-4-vinylpyridine). The optical limiting performance of FCA itself is poorer than that of its parent C60, while FCA incorporated

Richard Metzler, Christian Horn

In the original Evolutionary Minority Game, a segregation into two populations with opposing preferences is observed under many circumstances. We show that this segregation becomes more pronounced and more robust if the dynamics are changed slightly, such that strategies with above-average fitness become more frequent. Similar effects occur also for a genera

Magdalena Constantin, Michael Widom, Jose A. Miranda

The Saffman-Taylor viscous fingering problem is investigated for the displacement of a non-Newtonian fluid by a Newtonian one in a radial Hele-Shaw cell. We execute a mode-coupling approach to the problem and examine the morphology of the fluid-fluid interface in the weak shear limit. A differential equation describing the early nonlinear evolution of the in

N. Regnault, Th. Jolicoeur

We study the Quantum Hall phases that appear in the dilute limit of rotating Bose-Einstein condensates. By exact diagonalization in a spherical geometry we obtain the ground-state and low-lying excited states of a small number of bosons as a function of the filling fraction nu, ratio of the number of bosons to the number of vortices. We show the occurrence o

S. Buckiewicz, L. Dȩbski, W. Florek

Properties of a given symmetry group G are very important in investigation of a physical system invariant under its action. In the case of finite spin systems (magnetic rings, some planar macromolecules) the symmetry group is isomorphic with the dihedral group D_N. In this paper group-theoretical `parameters' of such groups are determined, especially dec

F. C. Alcaraz, Yu. G. Stroganov

We conjecture that the free-fermion part of the eigenspectrum observed recently for the $SU_q(N)$ Perk-Schultz spin chain Hamiltonian in a finite lattice with $q=\exp (iπ(N-1)/N)$ is a consequence of the existence of a special simple eigenvalue for the transfer matrix of the auxiliary inhomogeneous $SU_q(N-1)$ vertex model which appears in the nested Bethe a

C. Meyers

In the framework of the Ginzburg-Landau equation, the temperature dependence of the upper critical field of small ring-like superconductors is studied. At equilibrium small parts of the phase diagram show paramagnetism for width / radius ratios below 0.85. Their number and extension increase with the size of the hole. In these regions, only the inner part of

C. Capan, K. Behnia, Z. Z. Li, H. Raffy

We present a comparative study of Nernst effect and resistivity in underdoped samples of Bi$_2$Sr$_2$CuO$_{6+δ}$ and La$_{2-x}$Sr$_{x}$CuO$_4$. The Nernst effect presents a peak in a region of the H-T diagram where resistivity shows a non-metallic temperature dependence. Our results illustrate that the mechanism of dissipation in the mixed state of underdope

Y. Melean, D. Broseta, A. Hasmy, R. Blossey

We have studied the dispersive behaviour of imbibition fronts in a porous medium by X-ray tomography. Injection velocities were varied and the porous medium was initially prewetted or not. At low velocity in the prewetted medium, the imbibition profiles are found to be distinctly hyperdispersive. The profiles are anomalously extended when compared to tracer

P. Olsson, S. Teitel

The 3D uniformly frustrated XY model is simulated to search for a predicted "vortex loop blowout" transition within the vortex line liquid phase of a strongly type-II superconductor in an applied magnetic field. Results are shown to strongly depend on the precise scheme used to trace out vortex line paths. While we find evidence for a transverse vort

Wojciech Florek, Sylwia Bucikiewicz

The spin correlations ω^z_r, r=1,2,3, and the probability p_N$ of finding a system in the Neel state for the antiferromagnetic ring Fe(III)6 (the so-called `small ferric wheel&#39;) are calculated. States with magnetization M=0, total spin 0<=S<=15 and labeled by two (out of four) one-dimensional irreducible representations (irreps) of the point symmetry gro

A. Ramezanpour, V. Karimipour, A. Mashaghi

In this paper we consider a transformation which converts uncorrelated networks to correlated ones(here by correlation we mean that coordination numbers of two neighbors are not independent). We show that this transformation, which converts edges to nodes and connects them according to a deterministic rule, nearly preserves the degree distribution of the net

Yan Li, Slava V. Rotkin, Umberto Ravaioli

The electronic properties of carbon nanotubes in a uniform transverse field are investigated within a single orbital tight-binding model. For doped nanotubes, the dielectric function is found to depend not only on symmetry of the tube, but also on radius and Fermi level position. Bandgap opening/closing is predicted for zigzag tubes, while it is found that a

Tetsuya Takimoto, Takashi Hotta, Kazuo Ueda

Magnetism and superconductivity of new heavy fermion compounds CeTIn$_5$ (T=Co, Rh and Ir) are investigated by applying fluctuation exchange approximation to an orbital degenerate Hubbard model. The superconducting phase with $d_{x^2-y^2}$-symmetry is found to appear next to the antiferromagnetic phase with increasing the orbital splitting energy. The presen

Takashi Hotta, Elbio Dagotto

In this review, the present status of theories for manganites is discussed. The complex phase diagrams of these materials, with a variety of spin-charge-orbital ordering tendencies, is addressed using mean-field and Monte Carlo simulation techniques. The stability of the charge-ordered states, such as the CE-state at half-doping, appears to originate, in par

M. Grether, M. de Llano, M. A. Solís

Normal behavior of the thermodynamic properties of a Fermi gas in $d>2$ dimensions, integer or not, means monotonically increasing or decreasing of its specific heat, chemical potential or isothermal sound velocity, all as functions of temperature. However, for $0<d<2$ dimensions these properties develop a ``hump&#39;&#39; (or ``trough&#39;&#39;) which incre

K. M. O&#39;Hara, S. L. Hemmer, M. E. Gehm, S. R. Granade

We report on the observation of a highly-degenerate, strongly-interacting Fermi gas of atoms. Fermionic $^6$Li atoms in an optical trap are evaporatively cooled to degeneracy using a magnetic field to induce strong, resonant interactions. Upon abruptly releasing the cloud from the trap, the gas is observed to expand rapidly in the transverse direction while

J. C. Phillips

Mani et al. have observed [1] zero-resistance states (ZRS) and energy gaps in a surprising setting: ultrahigh-mobility GaAs/AlGaAs heterostructures that contain a two dimensional electron Landau system (2DELS) exhibit vanishing diagonal resistance without Hall resistance quantization at low temperatures and low magnetic fields when the specimen is subjected

D. Schmeltzer

At temperatures $T < {\hbar v_F}/{K_B d} \equiv T^{wire}$ the collective excitations are negligible and the spectrum of the short wire is dominated by the &#39;&#39;zero modes&#39;&#39; particle excitations. At temperature $ T > T^{wire}$ a spin polarized state controlled by the electron-electron interaction and electron density is identified at short times.

A. Marte, T. Volz, J. Schuster, S. Dürr

More than 40 Feshbach resonances in rubidium 87 are observed in the magnetic field range between 0.5 and 1260 G for various spin mixtures in the lower hyperfine ground state. The Feshbach resonances are observed by monitoring the atom loss, and their positions are determined with an accuracy of 30 mG. In a detailed analysis, the resonances are identified and

Paolo Politi, Claudio Castellano

Recently, the nucleation rate on top of a terrace during the irreversible growth of a crystal surface by MBE has been determined exactly. In this paper we go beyond the standard model usually employed to study the nucleation process, and we analyze the qualitative and quantitative consequences of two important additional physical ingredients: the nonuniformi

Guo-meng Zhao

We theoretically estimate the electron-phonon coupling constant lambda for metallic single-walled carbon nanotubes with a diameter of 1.4 nm. The partial electron-phonon coupling constant for the hardest phonon mode is estimated to be about 0.0036, in good agreement with that deduced from Raman scattering data assuming superconductivity above room temperatur

Guo-meng Zhao

The temperature dependent frequency shifts of the Raman active G-band have recently been measured by R.Walter et al. for single-walled carbon nanotubes containing different concentrations of the magnetic impurity Ni:Co. These Raman data can be quantitatively explained by magnetic pair-breaking effect on a superconductor with a mean-field transition temperatu

Masaaki Sakano, Robert S. Warwick, Anne Decourchelle

In X-rays, the Galactic Centre (GC) Region appears as a complex of diffuse thermal and non-thermal X-ray emission intermixed with a population of luminous discrete sources. Here we present some new findings from the XMM-Newton GC survey, focusing particularly on Sgr A*, Sgr A East, the Radio Arc region, and a newly discovered X-ray non-thermal filament.

Y. -H. Chu, C. -H. R. Chen, C. Danforth, B. C. Dunne

Narrow-band HST WFPC2 images reveal a bow-shock-like halo around the HII region N30B toward the B[e] supergiant Hen S22 located within the larger DEM L 106 nebula in the Large Magellanic Cloud. High-dispersion spectra of N30B show a narrow H-alpha emission component from the ionized gas; the velocity variations indicate a gas flow of -5 to -10 km/s in the vi

Robert C. Berrington, Charles D. Dermer

We have developed a numerical model for the temporal evolution of particle and photon spectra resulting from nonthermal processes at the shock fronts formed in merging clusters of galaxies. Fermi acceleration is approximated by injecting power-law distributions of particles during a merger event, subject to constraints on maximum particle energies. We consid

Christian Y. Cardall, Anthony Mezzacappa

Experience with core-collapse supernova simulations shows that accurate accounting of total particle number and 4-momentum can be a challenge for computational radiative transfer. This accurate accounting would be facilitated by the use of particle number and 4-momentum transport equations that allow transparent conversion between volume and surface integral

Konstantinos Tassis, Tom Abel, Greg L. Bryan, Michael L. Norman

We present first results from three-dimensional hydrodynamic simulations of the high redshift formation of dwarf galaxies. The simulations use an Eulerian adaptive mesh refinement technique to follow the non-equilibrium chemistry of hydrogen and helium with cosmological initial conditions drawn from a popular Lambda-dominated CDM model. We include the effect

Li-Xin Li

The evolution of magnetic fields frozen to a perfectly conducting plasma fluid around a Kerr black hole is investigated. We focus on the plunging region between the black hole horizon and the marginally stable circular orbit in the equatorial plane. Adopting the kinematic approximation where the dynamical effects of magnetic fields are ignored, we exactly so

A. Zandivarez, M. J. L. Dominguez, C. J. Ragone, H. Muriel

A comprehensive study on compactness has been carried out on the 2dF Galaxy Group Catalogue constructed by Merchán & Zandivarez. The compactness indexes defined in this work take into account different geometrical constraints in order to explore a wide range of possibilities. Our results show that there is no clear distinction between groups with high and lo

Jocelyn Tomkin

A new determination of the orbit of the Hyades double-lined spectroscopic binary HD 27149 is presented. The well-defined orbit provides the spectroscopic basis for an extremely accurate orbital parallax for the system -- in particular, the size of the relative orbit ($a\sin i = (a_1 + a_2)\sin i = (67.075 \pm 0.045) \times 10^6$ km) is accurate to $\pm 0.07$

Bradley E. Schaefer

The characteristic photon energy for Gamma Ray Bursts, E_peak, has a remarkably narrow distribution for bursts of similar peak flux, with values between 150 and 600 keV for most faint bursts. This result is surprising within the framework of internal shock models, since spectral shifts associated with the jet&#39;s blue shift (by a Lorentz factor of Gamma) a

S. Garcia-Burillo, F. Combes, A. Eckart, L. J. Tacconi

The NUclei of GAlaxies (NUGA) project is a combined effort to carry out a high-resolution (<1&#39;&#39;) interferometer CO survey of a sample of 12 nearby AGN spiral hosts, using the IRAM array. We map the distribution and dynamics of molecular gas in the inner 1 kpc of the nuclei with resolutions of 10-50 pc, and study the mechanisms for gas fueling of the

A. Finoguenov, S. Borgani, L. Tornatore, H. Boehringer

We carry out a comparison between observations and hydrodynamic simulations of entropy profiles of groups and clusters of galaxies. We use the Tree+SPH GADGET code to simulate four halos of sizes in the M_500 = 1.0 - 16.e13 h^-1 Msun range, corresponding to poor groups up to Virgo-like clusters. We concentrate on the effect of introducing radiative cooling,

Susumu Inoue, Takeru Ken Suzuki

We discuss the production of the element $^6$Li in the early Galaxy by cosmic rays accelerated at structure formation shocks, driven by the hierarchical merging of sub-Galactic halos during Galaxy formation. The salient features of this scenario are discussed and compared with observations of $^6$Li in metal-poor halo stars, including a recent Subaru HDS res

U. Heber, S. Dreizler, S. L. Schuh, S. O&#39;Toole

A small fraction of subluminous B stars show short-period, multiperiodic light variations and form the new class of pulsating star known as EC 14026 variables, after the prototype. The Multi-Site Spectroscopic Telescope (MSST) is a virtual instrument and is also the name of a collaboration that aims to open up a new observational window to provide access to

W. Pietsch, M. Ehle, F. Haberl, Z. Misanovic

In an XMM-Newton raster observation of the bright local group spiral galaxy M33 we study the population of X-ray sources (X-ray binaries, supernova remnants, super-shells) down to a 0.5-10 keV luminosity of 10^35 erg s^-1 -- more than a factor of 10 deeper than earlier ROSAT observations. EPIC spectra and hardness ratios are used to distinguish between diffe

Bradley E. Schaefer

Gamma-ray bursts (GRBs) are tremendous explosions visible across most of the Universe, certainly out to redshifts of z=4.5 and likely out to z~10. Recently, GRBs have been found to have a roughly constant explosive energy as well as to have two luminosity indicators (the spectral lag time and the variability) that can be used to derive the burst&#39;s lumino

Gordon I. Ogilvie, Michael R. E. Proctor

We demonstrate a close analogy between a viscoelastic medium and an electrically conducting fluid containing a magnetic field. Specifically, the dynamics of the Oldroyd-B fluid in the limit of large Deborah number corresponds to that of a magnetohydrodynamic (MHD) fluid in the limit of large magnetic Reynolds number. As a definite example of this analogy, we

G. I. Ogilvie

[Abridged] The turbulent stresses that lead to angular momentum transport in accretion discs have often been treated as resulting from an isotropic effective viscosity, related to the pressure through the alpha parametrization of Shakura & Sunyaev. This simple approach may be adequate for the simplest aspects of accretion disc theory, and was necessitated hi

F. Galliano, S. C. Madden, A. P. Jones, C. D. Wilson

We are modeling the spectra of dwarf galaxies from infrared to submillimeter wavelengths to understand the nature of the various dust components in low-metallicity environments, which may be comparable to the ISM of galaxies in their early evolutionary state. The overall nature of the dust in these environments appears to differ from those of higher metallic

Andrea Marcolini, Fabrizio Brighenti, Annibale D&#39;Ercole

We present 3D hydrodynamical simulations of galactic winds in dwarf, gas-rich galaxies. The galaxy is moving through the ICM of a small galaxy group at v=200 km/s. The ram pressure removes the galactic gas at large radii, but does not strongly influence the ISM near the center. A starburst generates a galactic wind. The newly produced metals are expelled in

Xiaolei Zhang, Kenneth G. Carpenter, Richard G. Lyon, Hubert Huet

The Fizeau Interferometer Testbed (FIT) is a collaborative effort between NASA&#39;s Goddard Space Flight Center, the Naval Research Laboratory, Sigma Space Corporation, and the University of Maryland. The testbed will be used to explore the principles of and the requirements for the full, as well as the pathfinder, Stellar Imager mission concept. It has a l

Christian Y. Cardall

Core-collapse supernovae can be used to place limits on dark matter candidate particles, but the strength of these limits depends on the depth of our theoretical understanding of these astrophysical events. To date, limitations on computing power have prevented inclusion of all the physics that would constitute a realistic simulation. The TeraScale Supernova

G. Fabbiano, A. Zezas, A. R. King, T. J. Ponman

We report the first results of the Chandra temporal monitoring of the ultra-luminous X-ray sources (ULXs) in the Antennae galaxies (NGC 4038/39). Observations at four different epochs, covering time scales of 2 years to 2 months, show variability in seven out of nine ULXs, confirming that they are likely to be accreting compact X-ray binaries (XRBs). The sev

A. M. Read

XMM-Newton background maps for the 3 EPIC instruments in their different instrument/mode/filter combinations and in several energy bands have been constructed using a superposition of many pointed observations. Event datasets for the different instrument/mode/filter combinations have also been constructed, with longer exposure times than previously created f

Claudia V. Rodrigues, Francisco J. Jablonski, Jane Gregorio-Hetem, Gabriel R. Hickel

We present BVRI CCD aperture polarization and near-infrared photometry of the proto-planetary nebula Hen 3-1475. Its intrinsic polarization is high and shows a strong spectral dependence. The position angles in all bands are perpendicular to the axis of the observed bipolar structure. A Monte Carlo code is used to model the intrinsic polarization of \hhe. Us

Ginevra Trinchieri

A hot phase of the interstellar medium has now been detected and studied in several objects through its X-ray emission. A proper assessment of its characteristics is relevant for our understanding of several aspects of galaxy properties, from the large scale distribution of matter to the stellar and galaxian evolution, to the dynamics of systems and to the f

D. M. Neumann, D. H. Lumb, G. W. Pratt, U. G. Briel

We present in this paper a substructure and spectroimaging study of the Coma cluster of galaxies based on XMM-Newton data. XMM-Newton performed a mosaic of observations of Coma to ensure a large coverage of the cluster. We add the different pointings together and fit elliptical beta-models to the data. We subtract the cluster models from the data and look fo

R. C. Walker, K. R. Anantharamaiah

The radio source 3C84, in NGC1275, has a two sided structure on parsec scales. The northern feature, presumed to be associated with a jet moving away from the Earth, shows strong evidence for free-free absorption. The ionized gas responsible for that absorption would be a source of detectable stimulated recombination line emission for a wide range of physica

Joshua N. Winn, David Rusin, Christopher S. Kochanek

We present multi-frequency VLBA observations of PMN J1632-0033, one of the few gravitationally lensed quasars suspected of having a central ``odd&#39;&#39; image. The central component has a different spectral index than the two bright quasar images. Therefore, either the central component is not a third image, and is instead the active nucleus of the lens g

Daniel H. McIntosh, Hans-Walter Rix, Nelson Caldwell

We compare V-band structural properties of cluster and field galaxies, to test whether much of the current cluster membership resulted from the transformation of infalling spirals into red early types. We use 140 galaxies from 3 z<0.6 Abell clusters (A85,A496,A754 - spectroscopic membership) with blue colors, and compare them to 80 field galaxies with simila

M. Loewe, C. Villavicencio

The density corrections, in terms of the isospin chemical potential $μ_I$, to the mass of the pions are studied in the framework of the SU(2) low energy effective chiral lagrangian. The pion decay constant $f_π(T, μ_{I})$ is also analized. As a function of temperature for $μ_I =0$, the mass remains quite stable, starting to grow for very high values of $T$,

Jun Zhang, Jiri Vala, Shankar Sastry, K. Birgitta Whaley

We provide an analytic way to implement any arbitrary two-qubit unitary operation, given an entangling two-qubit gate together with local gates. This is shown to provide explicit construction of a universal quantum circuit that exactly simulates arbitrary two-qubit operations in SU(4). Each block in this circuit is given in a closed form solution. We also pr

Cheng-Wei Chiang, Jonathan L. Rosner

The final-state phases in $\bar{B} \to D π, D^* π$, and $D ρ$ decays appear to follow a pattern similar to those in $D \to \bar{K} π$, $\bar{K}^* π$, and $\bar{K} ρ$ decays. Each set of processes is characterized by three charge states but only two independent amplitudes, so the amplitudes form triangles in the complex plane. For the first two sets the trian

Thorsten Ohl, Juergen Reuter

We study the cancellations among Feynman diagrams that implement the Ward and Slavnov-Taylor identities corresponding to the conserved supersymmetry current in supersymmetric quantum field theories. In particular, we show that the Faddeev-Popov ghosts of gauge- and supersymmetries never decouple from the physical fields, even for abelian gauge groups. The su

Jens Erler

I give an introduction and overview of recent developments in high precision tests of the Standard Model. This includes a summary of Z-pole measurements, a brief account of the NuTeV result on neutrino-nucleon scattering, the anomalous magnetic moment of the muon, and implications for the Higgs boson mass.

Dimitri Gioev

We study inequalities between general integral moduli of continuity of a function and the tail integral of its Fourier transform. We obtain, in particular, a refinement of a result due to D. B. H. Cline [2] (Theorem 1.1 below). We note that our approach does not use a regularly varying comparison function as in [2]. A corollary of Theorem 1.1 deals with the

Dinesh K. Srivastava, Charles Gale, T. C. Awes

We study the A+B -> l+ l- + jet +X process in nucleus-nucleus collisions at relativistic energies. The dilepton as well as the jet will pass through the matter produced in such collisions. The recoiling dilepton will carry information about the kinematical features of the jet, and will thus prove to be a very effective tool in isolating in-medium effects suc