April 2006 arXiv papers — page 34

Vladimir Kadets, Miguel Martin, Javier Meri

A Banach space $X$ has the Daugavet property if the Daugavet equation $\|\Id + T\|= 1 + \|T\|$ holds for every rank-one operator $T:X \longrightarrow X$. We show that the most natural attempts to introduce new properties by considering other norm equalities for operators (like $\|g(T)\|=f(\|T\|)$ for some functions $f$ and $g$) lead in fact to the Daugavet p

Kyousuke Uchino

We define a Courant bracket on an associative algebra using the theory of Hochschild homology, and we introduce the notion of Dirac algebra. We show that the bracket of an omni-Lie algebra is quite a kind of Courant bracket.

Antoniadis Jannis, Kontogeorgis Aristides

We construct configuration spaces for cyclic covers of the projective line that admit extra automorphisms and we describe the locus of curves with given automorphism group. As an application we provide examples of arbitrary high genus that are defined over their field of moduli and are not hyperelliptic.

Guido Gentile, Michele V. Bartuccelli, Jonathan H. B. Deane

We revisit a problem considered by Chow and Hale on the existence of subharmonic solutions for perturbed systems. In the analytic setting, under more general (weaker) conditions, we prove their results on the existence of bifurcation curves from the nonexistence to the existence of subharmonic solutions. In particular our results apply also when one has dege

Mark Watkins, Noam D. Elkies

We investigate a problem considered by Zagier and Elkies, of finding large integral points on elliptic curves. By writing down a generic polynomial solution and equating coefficients, we are led to suspect four extremal cases that still might have nondegenerate solutions. Each of these cases gives rise to a polynomial system of equations, the first being sol

Kazuhiro Hikami

We study quantum invariant Z(M) for cusped hyperbolic 3-manifold M. We construct this invariant based on oriented ideal triangulation of M by assigning to each tetrahedron the quantum dilogarithm function, which is introduced by Faddeev in studies of the modular double of the quantum group. Following Thurston and Neumann-Zagier, we deform a complete hyperbol

F. Malikov

We explain how sheaves of vertex algebras are related to mathematical structures encoded by a class of Lagrangians. The exposition is focused on two examples: the WZW model and the (1,1)-supersymmetric $σ$-model. We conclude by showing how to construct a family of vertex algebras with base the Barannikov-Kontsevich moduli space.

Adam E. Parker

This paper provides a GIT construction of the Moduli Space of Stable Maps as a GIT quotient of the Graph Space by SL(2,C). As a corollary, we get a birational map from the 0-pointed Moduli Space to a projective variety.

Kazuhiro Hikami

We study the SU(2) Witten--Reshetikhin--Turaev invariant for the Seifert fibered homology spheres with M-exceptional fibers. We show that the WRT invariant can be written in terms of (differential of) the Eichler integrals of modular forms with weight 1/2 and 3/2. By use of nearly modular property of the Eichler integrals we shall obtain asymptotic expansion

Corinna Ulcigrai

We consider suspension flows built over interval exchange transformations with the help of roof functions having an asymmetric logarithmic singularity. We prove that such flows are strongly mixing for a full measure set of interval exchange transformations.

Tom Bridgeland, Srikanth Iyengar

It is proved that a noetherian commutative local ring A containing a field is regular if there is a complex M of free A-modules with the following properties: M_i=0 for i not in [0,dim A]; the homology of M has finite length; H_0(M) contains the residue field of A as a direct summand. This result is an essential component in the proofs of the McKay correspon

Vladimir Retakh, Shirlei Serconek, Robert Lee Wilson

Few changes. We compute the Hilbert series of some algebras associated to directed graphs and related to factorizations of noncommutative polynomials.

Mark Watkins

We explain how to find a rational point on a rational elliptic curve of rank 1 using Heegner points. We give some examples, and list new algorithms that are due to Cremona and Delaunay. These are notes from a short course given at the Institut Henri Poincare in December 2004.

Yuxin Ge, Guofang Wang

We solve the $σ_2$-Yamabe problem for a non locally conformally flat manifold of dimension $n>8$.

J. M. Landsberg

I show that 2x2 matrices cannot be approximately multiplied using less than seven multiplications. In other words I show that the matrix multiplication operator is not in the sixth secant variety of the Segre produt of three $P^3$'s.

Marcos Rosenbaum, J. David Vergara, L. Román Juárez

We show that introducing an extended Heisenberg algebra in the context of the Weyl-Wigner-Groenewold-Moyal formalism leads to a deformed product of the classical dynamical variables that is inherited to the level of quantum field theory, and that allows us to relate the operator space noncommutativity in quantum mechanics to the quantum group inspired algebr

Igor A. Bandos, Jose A. de Azcarraga, Cesar Miquel-Espanya

The superspace formulation of the worldvolume action of twistor string models is considered. It is shown that for the Berkovits-Siegel closed twistor string such a formulation is provided by a N=4 twistor-like action of the tensionless superstring. A similar inverse twistor transform of the open twistor string model (Berkovits model) results in a dynamical s

Nicolás Hatcher, A. Restuccia, J. Stephany

We classify all massive irreducible representations of super Poincaré in D=10. New Casimir operators of super Poincaré are presented whose eigenvalues completely specify the representation. It is shown that a scalar superfield contains three irreducible representations of massive supersymmetry and we find the corresponding superprojectors. We apply these new

Gaetano Fiore

We briefly report on our recent results regarding the introduction of a notion of a q-quaternion and the construction of instanton solutions of a would-be deformed su(2) Yang-Mills theory on the corresponding SO_q(4)-covariant quantum space. As the solutions depend on some noncommuting parameters, this indicates that the moduli space of a complete theory wil

M. Alimohammadi, M. Khorrami

The large-N behavior of Yang-Mills and generalized Yang-Mills theories in the double-scaling limit is investigated. By the double-scaling limit, it is meant that the area of the manifold on which the theory is defined, is itself a function of N. It is shown that phase transitions of different orders occur, depending on the functional dependence of the area o

Shao-You Zhao, Wen-Li Yang, Yao-Zhong Zhang

Working in the $F$-basis provided by the factorizing $F$-matrix, the scalar products of Bethe states for the supersymmetric t-J model are represented by determinants. By means of these results, we obtain determinant representations of correlation functions for the model.

M. Beyer, W. Kilian, P. Krstonosic, K. Monig

We present a study of the sensitivity of an International Linear Collider (ILC) to electroweak parameters in the absence of a light Higgs boson. In particular, we consider those parameters that have been inaccessible at previous colliders, quartic gauge couplings. Within a generic effective-field theory context we analyze all processes that contain quasi-ela

A. A. Pankov, N. Paver, A. V. Tsytrinov

Non-standard scenarios described by effective interactions can manifest themselves indirectly, via corrections to the Standard Model cross sections. It should be desirable to identify at a given confidence level the source of such deviations among the different possible explanations. We here discuss the identification reach on gravity in extra dimensions fro

S. M. Bilenky, M. D. Mateev

We consider neutrino oscillations as non stationary phenomenon based on Schrodinger evolution equation and mixed neutrino states with definite flavor. We demonstrate that for such states invariance under translations in time does not take place. We show that time-energy uncertainty relation plays a crucial role in neutrino oscillations. We compare neutrino o

Amal Kr. Sarma, Hijam Zeen Devi, N. Nimai Singh

We present a comparison of the numerical prediction on baryon asymmetry of the Universe in different neutrino mass models. We start with a very brief review on the main formalism of baryogenesis via leptogenesis through decay of heavy right-handed Majorana neutrinos, and then calculate the baryon asymmetry of the universe for known six neutrino mass models v

I. I. Bigi

The importance of future studies of charm and $τ$ decays is emphasized as probes of New Physics: the most powerful tools are \cp asymmetries in charm and $τ$ decays both in partial widths and final state distributions. While these searches for \cp violation are instrumentalized in the search for and hopefully future analysis of New Physics, they might also s

N. Irges, F. Knechtli

We analyse non-perturbatively a five-dimensional SU(2) gauge theory compactified on the S^1/Z_2 orbifold. In particular, we present simulation results for the mass spectrum of the theory, which contains a Higgs and a photon. The Higgs mass is found to be free of divergences without fine-tuning. The photon mass is non-zero, thus providing us with the first la

The Belle Collaboration, F. J. Ronga

We report measurements of time dependent decay rates for $B^0 \to D^{(*)-}π^+$ decays and extraction of CP violation parameters that depend on $ϕ_3$. Using fully reconstructed $D^{(*)}π$ events and partially reconstructed $D^{*}π$ events from a data sample that contains 386 million $B\bar{B}$ pairs that was collected near the $Υ(4S)$ resonance, with the Bell

The BABAR Collaboration, B. Aubert

We report on a study of the decay B0bar -> D*+ omega pi- with the BABAR detector at the PEP-II B-factory at the Stanford Linear Accelerator Center. Based on a sample of 232 million BBbar decays, we measure the branching fraction BF(B0bar -> D*+ omega pi-) = (2.88 +/- 0.21(stat.) +/- 0.31(syst.)) \times 10^{-3}. We study the invariant mass spectrum of the ome

Jairzinho Ramos, Robert Gilmore

We derive source-free Maxwell-like equations in flat spacetime for any helicity "j" by comparing the transformation properties of the 2(2j+1) states that carry the manifestly covariant representations of the inhomogeneous Lorentz group with the transformation properties of the two helicity "j" states that carry the irreducible representations

Mátyás Vasúth, Balázs Mikóczi

Beyond point mass effects various contributions add to the radiative evolution of compact binaries. We present all the terms up to the second post-Newtonian order contributing to the rate of increase of gravitational wave frequency and the number of gravitational wave cycles left until the final coalescence for binary systems with spin, mass quadrupole and m

E. S. Moreira,, E. S. Oliveira

This work investigates how a conical singularity can affect the specific heat of systems. A free nonrelativistic particle confined to the lateral surface of a cone -- conical box -- is taken as a toy model. Its specific heat is determined as a function of the deficit angle and the temperature. For a vanishing deficit angle, the specific heat is that of a par

K. G. Arun, B. R. Iyer, M. S. S. Qusailah, B. S. Sathyaprakash

The Laser Interferometric Space Antenna (LISA) will observe supermassive black hole binary mergers with amplitude signal-to-noise ratio of several thousands. We investigate the extent to which such observations afford high-precision tests of Einstein's gravity. We show that LISA provides a unique opportunity to probe the non-linear structure of post-Newt

Emmanuel J. Candes, Philip R. Charlton, Hannes Helgason

This paper considers the problem of detecting nonstationary phenomena, and chirps in particular, from very noisy data. Chirps are waveforms of the very general form A(t) exp(iλϕ(t)), where λis a (large) base frequency, the phase ϕ(t) is time-varying and the amplitude A(t) is slowly varying. Given a set of noisy measurements, we would like to test whether the

Sreeram Vuppala

This paper presents an introduction to the Aryabhata algorithm for finding multiplicative inverses and solving linear congruences, both of which have applications in cryptography. We do so by the use of the least absolute remainders. The exposition of the Aryabhata algorithm provided here can have performance that could exceed what was described recently by

Alexey V. Melkikh

A model of an organism as an autonomous intelligent system has been proposed. This model was used to analyze learning of an organism in various environmental conditions. Processes of learning were divided into two types: strong and weak processes taking place in the absence and the presence of aprioristic information about an object respectively. Weak learni

L. M. Jensen, H. M. Nilsen, Gentaro Watanabe

We determine the effects on the BCS-BEC crossover of the energy dependence of the effective two-body interaction, which at low energies is determined by the effective range. To describe interactions with an effective range of either sign, we consider a single-channel model with a two-body interaction having an attractive square well and a repulsive square ba

P. G. Kevrekidis, R. Carretero-Gonzalez, D. J. Frantzeskakis, B. A. Malomed

We construct discrete analogs of Skyrmions in nonlinear dynamical lattices. The Skyrmion is built as a vortex soliton of a complex field, coupled to a dark radial soliton of a real field. Adjusting the Skyrmion ansatz to the lattice setting allows us to construct a "baby-Skyrmion" in two dimensions (2D) and extend it into the 3D case (1D counterparts

F. W. S. Lima, J. A. Plascak

We investigate the critical properties of the spin-3/2 Blume-Capel model in two dimensions on a random lattice with quenched connectivity disorder. The disordered system is simulated by applying the cluster hybrid Monte Carlo update algorithm and re-weighting techniques. We calculate the critical temperature as well as the critical point exponents $γ/ν$, $β/

F. Brouers, O. Sotolongo-Costa, A. Gonzalez, J. P. Pirard

We have derived a universal relaxation function for heterogeneous materials using the maximum entropy principle for nonextensive systems. The power law exponents of the relaxation function are simply related to a global fractal parameter and for large time to the entropy nonextensivity parameter q. For intermediate times the relaxation follows a stretched ex

M. Hatami, M. Zareyan

We show that shot noise in a diffusive ferromagnetic wire connected by tunnel contacts to two ferromagnetic electrodes can probe the intrinsic density of states and the extrinsic impurity scattering spin-polarization contributions in the polarization of the wire conductivity. The effect is more pronounced when the electrodes are perfectly polarized in opposi

Kléman Maurice, Meyer Claire, Nastishin A. Yuri

It is usual to think of Focal Conic Domains (FCD) as perfect geometric constructions in which the layers are folded into Dupin cyclides, about an ellipse and a hyperbola that are conjugate. This ideal picture is often far from reality. We have investigated in detail the FCDs in several materials that have a transition from a smectic A (SmA) to a nematic phas

Brigitte Leridon, Tai-Kai Ng, C. M. Varma

Due to the absence of a center of inversion in some superconducting compounds, a p-wave admixture to the dominant d-wave order parameter must exist. If time-reversal is also violated, an allowed invariant is the product of the d-wave, p-wave and an appropriately directed current. We show that this leads to an anomalous Josephson current for tunneling along t

G. Mannarini, R. Zimmermann

Memory and correlation effects in the interband absorption from quantum wells due to exciton-phonon dynamics are investigated. They are traced back to the frequency dependence and matrix character of the self energy arising in a 2nd Born theory. It is found that interpeak absorption increases with respect to the case in which this memory and correlation effe

M. Combescot, O. Betbeder-Matibet, V. Voliotis

We here propose a mechanism to teleport electrons between quantum dots through the transformation of a virtual bright exciton into a dark exciton. This mechanism relies on the interactions of two composite bosons: a pair of electrons with opposite spins, trapped in two dots and an electron-hole pair in a free exciton coupled to an unabsorbed pump pulse, whic

A. Isacsson, O. F. Syljuasen

We have applied a variational algorithm based on Projected Entangled Pair States (PEPS) to a two dimensional frustrated spin system, the spin-1/2 antiferromagnetic Heisenberg model on the Shastry-Sutherland lattice. We use the class of PEPS with internal tensor dimension D=2, the first step beyond product states (D=1 PEPS). We have found that the D=2 variati

A. V. Goncharov, A. A. Zhukov, V. V. Metlushko, G. Bordignon

Magnetization reversal mechanisms and impact of magnetization direction are studied in square arrays of interconnected circular permalloy nanorings using MOKE, local imaging, numerical simulations and transport techniques.

David L. Cheung

Using classical density functional theory (DFT) the effect of bringing a liquid crystal (LC) into contact with a porous substrate or matrix is investigated. The DFT used is a combination of the Onsager approximation to evaluate the excess free energy of the LC fluid and quenched annealed DFT to evaluate the interaction between the fluid and the porous substr

D. J. Heijs, V. A. Malyshev, J. Knoester

Using a model of Frenkel excitons coupled to a bath of acoustic phonons in the host medium, we study the temperature dependence of the dephasing rates and homogeneous line width in linear molecular aggregates. The model includes localization by disorder and predicts a power-law thermal scaling of the effective homogeneous line width. The theory gives excelle

C. Didraga, V. A. Malyshev, J. Knoester

We theoretically analyze the excitation energy transfer between two closely spaced linear molecular J-aggregates, whose excited states are Frenkel excitons. The aggregate with the higher (lower) exciton band edge energy is considered as the donor (acceptor). The celebrated theory of Förster resonance energy transfer (FRET), which relates the transfer rate to

Yu-Cheng Lin, Heiko Rieger, Nicolas Laflorencie, Ferenc Igloi

Using a numerical implementation of strong disorder renormalization group, we study the low-energy, long-distance properties of layers and bilayers of $S = 1/2$ Heisenberg antiferromagnets with different type of disorder: bond randomness, site and dimer dilution. Generally the systems exhibit an ordered and a disordered phase separated by a phase boundary on

Dmitry Pozdnyakov, Vadim Galenchik

In this study a method for calculation of the electron-phonon scattering rate in semiconductor structures with one-dimensional electron gas is developed. The energy uncertainty of electrons is taken into account.

Shinya Kasai, Yoshinobu Nakatani, Kensuke Kobayashi, Hiroshi Kohno

A magnetic vortex core in a ferromagnetic circular nanodot has a resonance frequency originating from the confinement of the vortex core. By the micromagnetic simulation including the spin-transfer torque, we show that the vortex core can be resonantly excited by an AC (spin-polarized) current through the dot and that the resonance frequency can be tuned by

F. Pollmann, P. Fulde, E. Runge

We study the dynamical properties of spinless fermions on the checkerboard lattice. Our main interest is the limit of large nearest-neighbor repulsion $V$ as compared with hopping $|t|$. The spectral functions show broad low-energy excitation which are due to the dynamics of fractionally charged excitations. Furthermore, it is shown that the fractional charg

Dmitry Pozdnyakov, Vadim Galenchik, Fadei Komarov, Vladimir Borzdov

The rates of electron scattering via phonons in the armchair single-wall carbon nanotubes were calculated by using the improved scattering theory within the tight-binding approximation. Therefore, the problem connected with the discrepancy of the scattering rates calculated in the framework of the classical scattering theory and ones predicted by experimenta

Masaru Onoda, Naoto Nagaosa

The interplay between incommensurate (IC) and random potentials is studied in a two-dimensional symplectic model with the focus on localization/delocalization problem. With the IC potential only, there appear wavefunctions localized along the IC wavevector while extended perpendicular to it. Once the disorder potential is introduced, these turn into two-dime

Akira Ohtomo, Harold Y. Hwang

We have studied the growth dynamics and electronic properties of SrTiO3-d homoepitaxial films by pulsed laser deposition. We find the two dominant factors determining the growth mode are the kinetics of surface crystallization and oxidation. When matched, persistent two-dimensional layer-by-layer growth can be obtained for hundreds of unit cells. By tuning t

O. Astafiev, Yu. A. Pashkin, Y. Nakamura, T. Yamamoto

To verify the hypothesis about the common origin of the low frequency 1/f noise and the quantum f noise recently measured in the Josephson charge qubits, we study temperature dependence of the 1/f noise and decay of coherent oscillations. T^2 dependence of the 1/f noise is experimentally demonstrated, which supports the hypothesis. We also show that dephasin

J. P. Kestner, L. -M. Duan

For a dilute atomic gas in a strong transverse trapping potential, one normally expects that, in the ground state, the gas will populate only the lowest transverse level. We show, however, that for the strongly interacting gas under a Feshbach resonance, the ground state includes a large fraction of atoms in excited levels of the trap, even if the gas is ver

M. F. Gelin, D. S. Kosov

We present a model for the description of orientational relaxation in hydrogen-bonding liquids. The model contains two relaxation parameters which regulate the intensity and efficiency of dissipation, as well as the memory function which is responsible for the short-time relaxation effects. It is shown that the librational portion of the orientational relaxa

C. Scott Wylie, Herbert Levine, David A. Kessler

We study 2D fronts propagating up a co-moving reaction rate gradient in finite number reaction-diffusion systems. We show that in a 2D rectangular channel, planar solutions to the deterministic mean-field equation are stable with respect to deviations from planarity. We argue that planar fronts in the corresponding stochastic system, on the other hand, are u

W. Selke

The fourth-order cumulant of the magnetization, the Binder cumulant, is determined at the phase transition of Ising models on square and triangular lattices, using Monte Carlo techniques. Its value at criticality depends sensitively on boundary conditions, details of the clusters used in calculating the cumulant, and symmetry of the interactions or, here, la

A. R. Subramaniam, I. A. Gruzberg, A. W. W. Ludwig, F. Evers

We develop the concept of surface multifractality for localization-delocalization (LD) transitions in disordered electronic systems. We point out that the critical behavior of various observables related to wave functions near a boundary at a LD transition is different from that in the bulk. We illustrate this point with a calculation of boundary critical an

Simon C. Benjamin

Ordered nanoarrays, i.e. regular patterns of quantum structures at the nanometre scale, have recently been synthesized in a wide range of systems. Here I explore a possible route to technological exploitation: assuming a simple form of bistability for the individual units, I find that arrays can compute in a way that is robust, efficient, programmable and hi

M. Sztyren

A hybrid discrete-continuous model of layered superconductors with interlayer Josephson couplings of arbitrary range is constructed. The conditions required by gauge invariance and thermodynamical stability of the model are determined. Some important special cases, in particular transition to the classic Lawrence-Doniach model, are discussed. The conditions

David A. Tilley, Dinshaw S. Balsara

We explore the importance of anisotropic thermal conduction in the evolution of supernova remnants via numerical simulations. The mean temperature of the bubble of hot gas is decreased by a factor of ~3 compared to simulations without thermal conduction, together with an increase in the mean density of hot gas by a similar factor. Thus, thermal conduction gr

M. M. Romanova, A. K. Kulkarni, M. Long, R. V. E. Lovelace

We performed 2D and full 3D magnetohydrodynamic simulations of disk accretion to a rotating star with an aligned or misaligned dipole magnetic field. We investigated the rotational equilibrium state and derived from simulations the ratio between two main frequencies: the spin frequency of the star and the orbital frequency at the inner radius of the disk. In

G. Bryden, C. A. Beichman, G. H. Rieke, J. A. Stansberry

With the MIPS camera on Spitzer, we have searched for far-infrared emission from dust in the planetary system orbiting pulsar PSR 1257+12. With accuracies of 0.05 mJy at 24 um and 1.5 mJy at 70 um, photometric measurements find no evidence for emission at these wavelengths. These observations place new upper limits on the luminosity of dust with temperatures

B. A. Twarog, S. Corder, B. J. Anthony-Twarog

CCD photometry on the intermediate-band uvbyCa H beta system is presented for the anticenter, intermediate-age open cluster, Melotte 71. Restricting the data to probable single members of the cluster using the color-magnitude diagram and the photometric indices alone generates a sample of 48 F dwarfs on the unevolved main sequence. The average E(b-y) = 0.148

Massimo Della Valle

We review the observational status of the supernova/gamma-ray burst connection. Present data suggest that SNe associated with GRBs form a heterogeneous class of objects including both bright and faint hypernovae and perhaps also `standard' Ib/c events. Evidence for association with other types of core-collapse SNe (e.g. IIn) is much weaker. After combini

M. Della Valle, D. Malesani, J. S. Bloom, S. Benetti

We report observations of GRB 050525A, for which a Gemini North spectrum shows its redshift to be z = 0.606. This is the third closest long GRB discovered by Swift. We observed its afterglow using the VLT, Gemini and TNG telescopes to search for an associated SN. We find that the early-time light curve is described by a broken power law with a break at t ~ 0

J. L. Donley, B. S. Koribalski, L. Staveley-Smith, R. C. Kraan-Korteweg

We report the discovery of a very HI-massive disk galaxy, HIZOA J0836-43, at a velocity of v_hel = 10689 km/s, corresponding to a distance of 148 Mpc (assuming H_0=75 km/s/Mpc). It was found during the course of a systematic HI survey of the southern Zone of Avoidance (|b| < 5 deg) with the multibeam system at the 64m Parkes radio telescope. Follow-up observ

E. M. Schlegel, R. Petre

SN1988Z is the most luminous X-ray-emitting supernova, initially detected in 1995 using the ROSAT HRI with a luminosity of ~8x10^40 erg s^-1 (Fabian & Terlevich 1996). Its high luminosity was ascribed to expansion of the blast wave into an especially dense circumstellar medium. In this paper, we describe a recent observation of SN1988Z using the ACIS detecto

A. Panaitescu, P. Meszaros, D. Burrows, J. Nousek

The power-law decay of the X-ray emission of GRB afterglows 050319, 050401, 050607, 050713A, 050802 and 050922C exhibits a steepening at about 1--4 hours after the burst which, surprisingly, is not accompanied by a break in the optical emission. If it is assumed that both the optical and X-ray afterglows arise from the same outflow then, in the framework of

L. M. Rebull, J. R. Stauffer, S. T. Megeath, J. L. Hora

Early observations of T Tauri stars suggested that stars with evidence of circumstellar accretion disks rotated slower than stars without such evidence, but more recent results are not as clear. Near-IR circumstellar disk indicators, though the most widely available, are subject to uncertainties that can result from inner disk holes and/or the system inclina

R. Cassano, G. Brunetti, G. Setti

The most important evidence of non-thermal phenomena in galaxy clusters comes from Giant Radio Halos (GRHs), synchrotron radio sources extended over Mpc scales, detected in a growing number of massive galaxy clusters. A promising possibility to explain these sources is given by &#34;in situ&#34; stochastic reacceleration of relativistic electrons by turbulen

V. Holzwarth, D. H. Mackay, M. Jardine

Observations of rapidly rotating solar-like stars show a significant mixture of opposite-polarity magnetic fields within their polar regions. To explain these observations, models describing the surface transport of magnetic flux demand the presence of fast meridional flows. Here, we link sub-surface and surface magnetic flux transport simulations to investi

James Bock, Sarah Church, Mark Devlin, Gary Hinshaw

One of the most spectacular scientific breakthroughs in past decades was using measurements of the fluctuations in the cosmic microwave background (CMB) to test precisely our understanding of the history and composition of the Universe. This report presents a roadmap for leading CMB research to its logical next step, using precision polarization measurements

Ch. Stuetz, S. Bagnulo, E. Jehin, C. Ledoux

It is unclear whether chemically peculiar stars of the upper main sequence represent a class completely distinct from normal A-type stars, or whether there exists a continuous transition from the normal to the most peculiar late F- to early B-type stars. A systematic abundance analysis of open cluster early-type stars would help to relate the observed differ

Deidre A. Hunter, Bruce G. Elmegreen, Emily Martin

We present mid-infrared to optical properties of 22 representative irregular galaxies: 18 Im, 3 BCDs, and one Sm. The mid-IR is based on images from the Spitzer Space Telescope archives. The 3.6 and 4.5 micron bands and the UBVJHK images are used to examine disk morphology and the integrated and azimuthally averaged magnitudes and colors of stars. The non-st

M. G. F. Kirsch, G. Schoenherr, E. Kendziorra, M. J. Freyberg

We discuss the current X-ray view of the Crab Nebula and Pulsar, summarising our analysis of observations of the source with the EPIC-pn camera on board the XMM-Newton observatory. Different modes of EPIC-pn were combined in order to yield a complete scenario of the spectral properties of the Crab resolved in space and time (pulse phase). In addition we give

J. S. Yadav

We investigate the association between the accretion disk during radio plateau state and the following superluminal relativistic radio jets with peak intensity varies from 200 mJy to 1000 mJy observed over a period of five years and present the evidences of direct accretion disc-jet connection in microquasar GRS 1915+105. We have analysed RXTE PCA/HEXTE X-ra

Jelena Ninkovic, Peter Christ, Godehard Angloher, Dieter Hauff

We present a new technique developed for the measurement of the scintillation efficiency of nuclear recoils in solid scintillators. Using this technique we measured the quenching of the scintillation efficiency for the various recoiling nuclei in CaWO4 crystals which are used in direct Dark Matter searches.

E. Maiorano, N. Masetti, E. Palazzi, S. Savaglio

We report on the photometric, spectroscopic and polarimetric, monitoring of the optical afterglow of Gamma-Ray Burst (GRB) 030328 detected by HETE-2. Photometry, collected at 7 different telescopes, shows that a smoothly broken powerlaw decay, with indices alpha_1 = 0.76 +/- 0.03, alpha_2 = 1.50 +/- 0.07 and a break at t_b = 0.48 +/- 0.03 days after the GRB,

P. Lambert, S. Pires, J. Ballot, R. A. Garcia

Context: The detection and identification of oscillation modes (in terms of their $\ell$, $m$ and successive $n$) is a great challenge for present and future asteroseismic space missions. The &#34;peak tagging&#34; is an important step in the analysis of these data to provide estimations of stellar oscillation mode parameters, i.e., frequencies, rotation rat

Andrew J. Fox, Blair D. Savage, Bart P. Wakker

(ABRIDGED) We present a Far-Ultraviolet Spectroscopic Explorer survey of highly ionized high-velocity clouds (HVCs) in 66 extragalactic sight lines. We find a total of 63 high-velocity O VI absorbers, 16 with 21 cm-emitting H I counterparts and 47 ``highly ionized&#39;&#39; absorbers without 21 cm emission. 11 of these high-velocity O VI absorbers are positi

Luis P. Chimento, Ruth Lazkoz

We consider multiple k-essence sources and obtain the conditions their kinetic functions must satisfy so that purely kinetic k-essences lead to models with phantom barrier crossing. After that, we show that polynomial kinetic functions allow the integration of the dynamical equations determining the geometry and the k-fields. The models thus obtained have ac

M. Gromadzki, M. Mikolajewski, T. Tomov, I. Bellas-Velidis

UBVRI photometry observations of 10 symbiotic stars and related objects obtained in the period 2002-2003 are presented. Analysing differential light curves we found rapid light variations with timescales of tens of minutes and significant amplitudes in the well-known flickerers MWC 560, RS Oph, V407 Cyg and T CrB. MWC 560 and V407 Cyg demonstrate quasi perio

Christine Thurl, Penny D. Sackett, Peter H. Hauschildt

We present work on H alpha spectral line characteristics in PHOENIX stellar model atmospheres and their comparison to microlensing observations. We examine in detail the H alpha equivalent width (EW) and the line shape characteristics for effective temperatures of 4500K< Teff < 5600K where H alpha is a strong spectral feature. We find that H alpha EW in mode

M. J. Reboucas, J. S. Alcaniz

Given the wealth of increasingly accurate cosmological observations, especially the recent results from the WMAP, and the development of methods and strategies in the search for cosmic topology, it is reasonable to expect that we should be able to detect the spatial topology of the Universe in the near future. Motivated by this, we examine to what extent a p

Michael Galperin, Abraham Nitzan, Mark A. Ratner

The submitted Comment is based on using an isolated quantum dot approach to discuss the situation where the coupling to the leads is considerable (not negligible). This finite lead coupling is the situation in most molecular transport junctions. In such situations the population on the molecule is not static and dynamical effects (fluctuations) are crucial.

Kentaro Nomura, A. H. MacDonald

Graphene is a two-dimensional carbon material with a honeycomb lattice and Dirac-like low-energy excitations. When Zeeman and spin-orbit interactions are neglected its Landau levels are four-fold degenerate, explaining the $4 e^2/h$ separation between quantized Hall conductivity values seen in recent experiments. In this paper we derive a criterion for the o

Jeffrey E. Marchese, Matteo Cirillo, Niels Grønbech-Jensen

We present evidence for a close analogy between the nonlinear behavior of a pulsed microwave-driven Josephson junction at low temperature and the experimentally observed behavior of Josephson systems operated below the quantum transition temperature under similar conditions. We specifically address observations of Ramsey-type fringe oscillations, which can b

H. M. Cataldo

We develop a microscopic model of mutual friction represented by the dissipative dynamics of a normal fluid flow which interacts with the helical normal modes of vortices comprising a lattice in thermal equilibrium. Such vortices are assumed to interact with the quasiparticles forming the normal fluid through a pseudomomentum-conserving scattering Hamiltonia

Ben Green

These are notes to accompany four lectures that I gave at the School on Additive Combinatorics, held in Montreal, Quebec between March 30th and April 5th 2006. My aim is to introduce ``quadratic fourier analysis&#39;&#39; in so far as we understand it at the present time. Specifically, we will describe ``quadratic objects&#39;&#39; of various types and their

Joanna A. Ellis-Monaghan, Irasema Sarmiento

The vertex-nullity interlace polynomial of a graph, described by Arratia, Bollobás and Sorkin as evolving from questions of DNA sequencing, and extended to a two-variable interlace polynomial by the same authors, evokes many open questions. These include relations between the interlace polynomial and the Tutte polynomial and the computational complexity of t

Jin He

The starting point of quantum mechanics is the relationship between energy and momentum: energy is proportional to the squared momentum! As a result, energy and momentum have not been treated equally. The wave equation required by quantization is a differential equation which accordingly, does not treat time and space equally. As a result, the Planck constan

Nathaniel R. Butler

We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~10^7s. We find that most afterglows are consistent with pure power-laws plus extinction. Significant outliers to the population exist at the 5-10% level and have anomalously soft, possibly thermal spectra. Four bursts are singled out via possible

E. Piasetzky, M. Sargsian, L. Frankfurt, M. Strikman

We analyze recent data from high-momentum-transfer $(p,pp)$ and $(p,ppn)$ reactions on Carbon. For this analysis, the two-nucleon short-range correlation (NN-SRC) model for backward nucleon emission is extended to include the motion of the NN-pair in the mean field. The model is found to describe major characteristics of the data. Our analysis demonstrates t

Donghui Jeong, Eiichiro Komatsu

We compare the non-linear matter power spectrum in real space calculated analytically from 3rd-order perturbation theory with N-body simulations at 1<z<6. We find that the perturbation theory prediction agrees with the simulations to better than 1% accuracy in the weakly non-linear regime where the dimensionless power spectrum, Delta^2(k)=k^3P(k)/2pi^2, whic