May 2004 arXiv papers — page 8

Feng Ding, Sergey V. Buldyrev, Nikolay V. Dokholyan

We develop a coarse-grained protein model with a simplified amino acid interaction potential. We perform discrete molecular dynamics folding simulations of a small 20 residue protein - Trp-cage - from a fully extended conformation. We demonstrate the ability of the Trp-cage model to consistently reach conformations within 2angstrom backbone root-mean-square

B. P. Lavrov, M. S. Ryazanov

A method is proposed for determining rovibronic term values of diatomics from experimental data on the wavenumbers of electronic-vibro-rotational spectral lines. In contrast to existing techniques, the new one is based on the Rydberg-Ritz principle only. It is shown that a link between a set of rovibronic term values and a set of wavenumbers of observed rovi

T. L. Gill, W. W. Zachary, J. Lindesay

In this paper, we construct a parallel image of the conventional Maxwell theory by replacing the observer-time by the proper-time of the source. This formulation is mathematically, but not physically, equivalent to the conventional form. The change induces a new symmetry group which is distinct from, but closely related to the Lorentz group, and fixes the cl

Roberto A. Monetti, Wolfram Bunk, Ferdinand Jamitzky, Christoph Raeth

We present a methodology for detecting non-linearities in data sets based on the characterization of the structural features of the Fourier phase maps. A Fourier phase map is a 2D set of points $M= \{(ϕ_{\vec{k}}, ϕ_{\vec{k} + \vecΔ})\}$, where $ ϕ_{\vec{k}}$ is the phase of the $k$-mode of the Fourier transform of the data set and $\vecΔ$ a phase shift. The

G. Gaigalas, S. Fritzsche, I. P. Grant

A program for computing pure angular momentum coefficients in relativistic atomic structure for any scalar one- and two-particle operator is presented. The program, written in Fortran 90/95 and based on techniques of second quantization, irreducible tensorial operators, quasispin and the theory of angular momentum, is intended to replace existing angular coe

G. Gaigalas, S. Fritzsche

A program RCFP will be presented for calculating standard quantities in the decomposition of many-electron matrix elements in atomic structure theory. The list of quantities wich are supported by the present program includes the coefficients of fractional parentage, the reduced coefficients of fractional parentage, the reduced matrix elements of the unit ope

Tarun Kr. Barik, Anushree Roy, Sayan Kar

Interfering liquid surface waves are generated by electrically driven vertical oscillations of two or more equispaced pins immersed in a liquid (water). The corresponding intensity distribution, resulting from diffraction of monochromatic light by the reflection phase grating formed on the liquid surface, is calculated theoretically and found to tally with e

Masashi Kaneta, Nu Xu

We will report centrality dependence of chemical freeze-out temperature ($T_{ch}$), light quark chemical potential ($μ_{q}$), strange quark chemical potential ($μ_{s}$), and strangeness saturation factor ($γ_{s}$) in Au+Au collisions at $\sqrt{s_{NN}}$ = 130 and 200 GeV. A systematic study for combination of ratios for chemical freeze-out fit is studied and

A. Capella, E. G. Ferreiro, A. B. Kaidalov, D. Sousa

We propose a model of suppression of $π^0$'s based on two different effects: at low $p_T$ we take into account the shadowing corrections, while at large $p_T$ the suppression is produced due to the interaction of the large $p_T$ pion with the dense medium created in the collision. The main features of the data on $AuAu$ and $dAu$ collisions are reproduce

A. Shukla, P. K. Raina, R. Chandra, P. K. Rath

The two neutrino positron double beta decay of $^{106}$Cd for 0$^{+} \to $ 0$^{+}$ transition has been studied in the Hartree-Fock-Bogoliubov model in conjunction with the summation method. In the first step, the reliability of the intrinsic wave functions of $^{106}$Cd and $^{106}$Pd nuclei has been tested by comparing the theoretically calculated results f

A. Shafi, S. Prakhov, I. I. Strakovsky, W. J. Briscoe

Differential cross sections for the process pi^- p -> gamma n have been measured at Brookhaven National Laboratory's Alternating Gradient Synchrotron with the Crystal Ball multiphoton spectrometer. Measurements were made at 18 pion momenta from 238 to 748 MeV/c, corresponding to E_gamma for the inverse reaction from 285 to 769 MeV. The data have been use

J. Aclander, J. Alster, G. Asryan, Y. Averiche

We summarize the results of two experimental programs at the Alternating Gradient Synchrotron of BNL to measure the nuclear transparency of nuclei measured in the A(p,2p) quasielastic scattering process near 90 Deg .in the pp center of mass. The incident momenta varied from 5.9 to 14.4 GeV/c, corresponding to 4.8 < Q^2 < 12.7 (GeV/c)^2. First, we describe th

R. Chacon

The work presents two examples of simple mathematical formulas which are natural nonlinear modifications (one being a generalization) of Gielis&#39; formula. These formulas involve a comparable number of parameters and provide non-Platonic representations of a vast diversity of natural shapes and patterns by incorporating diverse aspects of asymmetry and see

T. L. Gill, S. Basu, W. W. Zachary, V. Steadman

In this paper we show that a result of Gross and Kuelbs, used to study Gaussian measures on Banach spaces, makes it possible to construct an adjoint for operators on separable Banach spaces. This result is used to extend well known theorems of von Neumann and Lax. We also partially solve an open problem on the existence of a Markushevich basis with unit norm

T. L. Gill, W. W Zachary

In this paper, we provide a representation theory for the Feynman operator calculus. This allows us to solve the general initial-value problem and construct the Dyson series. We show that the series is asymptotic, thus proving Dyson&#39;s second conjecture for QED. In addition, we show that the expansion may be considered exact to any finite order by produci

Tobias Ekholm, Brian White, Daniel Wienholtz

This paper proves that classical minimal surfaces of arbitrary topological type with total boundary curvature at most 4πmust be smoothly embedded. Related results are proved for varifolds and for soap film surfaces.

Tatsuya Tsukamoto, Akira Yasuhara

J.P. Levine showed that the Conway polynomial of a link is a product of two factors: one is the Conway polynomial of a knot which is obtained from the link by banding together the components; and the other is determined by the $\barμ$-invariants of a string link with the link as its closure. We give another description of the latter factor: the determinant o

Michel Enock

In a former article, in collaboration with Jean-Michel Vallin, we have constructed two &#34;quantum groupo\&#34;ıds&#34; dual to each other, from a depth 2 inclusion of von Neumann algebras $M_0\subset M_1$, in such a way that the canonical Jones&#39;tower associated to the inclusion can be described as a tower of successive crossed-products by these two str

B. Abdesselam, R. Chakrabarti, A. Yanallah, M. B. Zahaf

Recently, a class of transformations of $R_q$-matrices was introduced such that the $q \to 1$ limit gives explicit nonstandard $R_h$-matrices. The transformation matrix is singular as $q \to 1$. For the transformed matrix, the singularities, however, cancel yielding a well-defined construction. We have shown that our method can be implemented systematically

Maya Mohsin Ahmed

We describe how to construct and enumerate Magic squares, Franklin squares, Magic cubes, and Magic graphs as lattice points inside polyhedral cones using techniques from Algebraic Combinatorics. The main tools of our methods are the Hilbert Poincare series to enumerate lattice points and the Hilbert bases to generate lattice points. We define polytopes of ma

Victoria Powers, Bruce Reznick, Claus Scheiderer, Frank Sottile

David Hilbert proved that a non-negative real quartic form f(x,y,z) is the sum of three squares of quadratic forms. We give a new proof which shows that if the complex plane curve Q defined by f is smooth, then f has exactly 8 such representations, up to equivalence. They correspond to those real 2-torsion points of the Jacobian of Q which are not represente

Arnold W. Miller

For $X$ a separable metric space define $\pp(X)$ to be the smallest cardinality of a subset $Z$ of $X$ which is not a relative $\ga$-set in $X$, i.e., there exists an $\om$-cover of $X$ with no $\ga$-subcover of $Z$. We give a characterization of $\pp(2^\om)$ and $\pp(\om^\om)$ in terms of definable free filters on $\om$ which is related to the psuedointerse

Krzysztof Burdzy

There exists a planar domain with piecewise smooth boundary and one hole such that the second eigenfunction for the Laplacian with Neumann boundary conditions attains its maximum and minimum inside the domain.

János Kollár

A Seifert bundle over a variety X is a variety Y with a proper action of the multiplicative group such that the quotient is X. The topological version of this notion (using circle actions) was introduced by Seifert, the holomorphic version by Orlik and Wagreich. The aim of this paper is to provide the foundational results for Seifert bundles over an arbitrar

Bo-Yong Chen

We prove that the Bergman and the Teichmuller metrics are equivalent on Teichmuller spaces.

Paolo Ghiggini

Using convex surfaces and Kanda&#39;s classification theorem, we classify Legendrian isotopy classes of Legendrian linear curves in all tight contact structures on $T^3$. Some of the knot types considered in this article provide new examples of non transversally simple knot types.

S. A. Merkulov

A De Rham model for string topology based on the theory of iterated integrals is presented.

Adrian S. Lewis, Pablo A. Parrilo, Motakuri V. Ramana

In 1958 Lax conjectured that hyperbolic polynomials in three variables are determinants of linear combinations of three symmetric matrices. This conjecture is equivalent to a recent observation of Helton and Vinnikov.

Yiming Long, Chaofeng Zhu

For any given compact C^2 hypersurface Σin {\bf R}^{2n} bounding a strictly convex set with nonempty interior, in this paper an invariant \varrho_n(Σ) is defined and satisfies \varrho_n(Σ)\ge [n/2]+1, where [a] denotes the greatest integer which is not greater than a\in {\bf R}. The following results are proved in this paper. There always exist at least ρ_n(

Daniel Robles-Llana, Martin Rocek

We give a direct computational proof of N=2 Seiberg duality for arbitrary quivers, and find the action on the Fayet-Iliopoulos parameters. We also find a new analogous classical duality for Kahler potentials of N=1 quivers that generalizes the trivial duality Gr(N,N+M) ~ Gr(M,N+M) for Grassmannians.

Paul H. Frampton

The use of the AdS/CFT correspondence to arrive at quiver gauge field theories is dicussed, focusing on the orbifolded case without supersymmetry. An abelian orbifold with the finite group $Z_{p}$ can give rise to a $G = SU(N)^p$ gauge group with chiral fermions and complex scalars in different bi-fundamental representations of $G$. The precision measurement

Dorothea Bahns

It is shown that the Hamiltonian approach for a $ϕ^3$-interaction on the 4-dimensional noncommutative Minkowski space leads to an ultraviolet finite $S$-matrix if the noncommutativity is averaged at each vertex.

C. Wetterich

We suggest that the difference between time and space is due to spontaneous symmetry breaking. In a theory with spinors the signature of the metric is related to the signature of the Lorentz-group. We discuss a higher symmetry that contains pseudo-orthogonal groups with arbitrary signature as subgroups. The fundamental asymmetry between time and space arises

R. Ahl Laamara, M. Ait Ben Haddou, A Belhaj, L. B Drissi

In this paper, we provide a general classification of supersymmeric QFT$_{4}$s into three basic sets: ordinary, affine and indefinite classes. The last class, which has not been enough explored in literature, is shown to share most of properties of ordinary and affine super QFT$_{4}$s. This includes, amongst others, its embedding in type II string on local C

C. G. Beneventano, E. M. Santangelo

After a brief discussion of elliptic boundary problems and their properties, we concentrate on a particular example: the Euclidean Dirac operator in two dimensions, with its domain determined by local boundary conditions. We discuss the meromorphic structure of the zeta function of the associated second order problem, as well as the main characteristic of th

Z. Haba

If we restrict a quantum field defined on a regular D dimensional curved manifold to a d dimensional submanifold then the resulting field will still have the singularity of the original D dimensional model. We show that a singular background metric can force the restricted field to behave as a d dimensional quantum field.

P. P. Fiziev

In this talk we consider the geometrical basis for the reduction of the relativistic 2-body problem, much like the non-relativistic one, to describing the motion of an effective particle in an external field. It is shown that this possibility is deeply related with the Lobachevsky geometry. The concept of relativistic reduced mass and effective relativistic

Andre Miemiec, Igor Schnakenburg

Starting from a nonlinear realisation of eleven dimensional supergravity based on the group G11, whose generators appear as low level generators of E11, we present a super extended algebra, which leads to a covariant derivative of spinors identical to the Killing spinor equation of this theory. A similar construction leads to the Killing spinor equation of N

Sven Heinemeyer, Dominik Stöckinger, Georg Weiglein

We present the up to now most precise evaluation of electroweak and supersymmetric contributions to the anomalous magnetic moment of the muon \amu, describing in detail also the calculational techniques. We calculate the bosonic two-loop contributions in the Standard Model without the approximation of a heavy Higgs-boson mass, finding corrections up to 0.2*1

P. Bicudo

We study the Theta+(1540) discovered at SPring-8. We apply Quark Model techniques, that explain with success the repulsive hard core of nucleon-nucleon and kaon-nucleon exotic scattering, and the short range attraction present in pion-nucleon and pion-pion non-exotic scattering. We find a K-N repulsion which excludes the Theta+ as a K-N s-wave pentaquark. We

G. Belanger, F. Boudjema, A. Pukhov, A. Semenov

We present the latest version of micromegas, a code that calculates the relic density of the lightest supersymmetric particle in the MSSM. All tree-level processes for the annihilation of the LSP are included as well as all possible coannihilation processes with neutralinos, charginos, sleptons, squarks and gluinos. The cross-sections extracted from CalcHEP

E. D. M. Kavoussanaki

The subject of topological defects has become a very attractive field of study given its apparent relevance to as diverse systems as the early universe and condensed matter. As usually envisaged the topology of the manifold M of the minima of the relevant to our physical system effective potential V, provides reliable information about the capacity of that s

A. A. Arkhipov

An analysis of the recent results from several experimental groups reported observation of a new $Θ$ baryon has been presented from a view point of the unified picture for hadron spectra developed early \cite{12}. It is shown that, in fact, two different $Θ$ baryons have been discovered. We have also established that both $Θ$ baryons are excellently incorpor

C. Bernet

The COMPASS experiment will determine the gluon polarization in the nucleon $ΔG/G$ from the double helicity asymmetry measured in the scattering of a 160 GeV muon beam on a longitudinally polarized deuteron target, by selecting the photon-gluon fusion reaction. This reaction can be tagged either by the production of open charm, or by the production of high $

B. Aubert, BABAR Collaboration

We establish upper limits on branching fractions for B0 decays to final states where the decay products are purely invisible (i.e., no observable final state particles) and for B0 decays to nu nubar gamma. Within the Standard Model, these decays have branching fractions that are below current experimental sensitivity, but various models of physics beyond the

Olga V. Babourova, Boris N. Frolov

The variational theory of the perfect hypermomentum fluid is developed. The new type of the generalized Frenkel condition is considered. The Lagrangian density of such fluid is stated, and the equations of motion of the fluid and the Weyssenhoff-type evolution equation of the hypermomentum tensor are derived. The expressions of the matter currents of the flu

Lili Ma, YangQuan Chen, Kevin L. Moore

This paper presents a blind detection and compensation technique for camera lens geometric distortions. The lens distortion introduces higher-order correlations in the frequency domain and in turn it can be detected using higher-order spectral analysis tools without assuming any specific calibration target. The existing blind lens distortion removal method o

Taneli Mielikäinen, Esko Ukkonen

The maximum intersection problem for a matroid and a greedoid, given by polynomial-time oracles, is shown $NP$-hard by expressing the satisfiability of boolean formulas in 3-conjunctive normal form as such an intersection. The corresponding approximation problems are shown $NP$-hard for certain approximation performance bounds. Moreover, some natural paramet

L. L. Gonçalves, L. P. S. Coutinho, J. P. de Lima

The one-dimensional XXZ model (s=1/2) in a transverse field, with uniform long-range interactions among the transverse components of the spins, is studied. The model is exactly solved by introducing the Jordan-Wigner transformation and the integral Gaussian transformation. The complete critical behaviour and the critical surface for the quantum and classical

Jun-Qiang Lu, Jian Wu, Wenhui Duan, Bing-Lin Gu

Two mechanisms that drive metal-to-semiconductor transitions in single-walled carbon nanotubes are theoretically analyzed through a simple tight-binding model. By considering simple structural trends, the results demonstrate that metal-to-semiconductor transitions can be induced more readily in metallic zigzag nanotubes than in armchair nanotubes. Furthermor

Sankalpa Ghosh

The occurrence of vortices in atomic Bose-Einstein condensates (BEC) enables a description of their superfluid behaviour. In this article we present a pedagogical introduction to the vortex physics in trapped atomic BECs. The mechanism of the vortex nucleation in an atomic BEC is discussed in detail. We also discuss a recently proposed approach which treats

M. B. Hastings

We consider gapped systems governed by either quantum or Markov dynamics, with the low-lying states below the gap being approximately degenerate. For a broad class of dynamics, we prove that ground or stationary state correlation functions can be written as a piece decaying exponentially in space plus a term set by matrix elements between the low-lying state

Wei-Li Lee, Satoshi Watauchi, V. L. Miller, R. J. Cava

In a ferromagnet, an applied electric field $\bf E$ invariably produces an anomalous Hall current ${\bf J}_H$ that flows perpendicular to the plane defined by $\bf E$ and $\bf M$ (the magnetization). For decades, the question whether ${\bf J}_H$ is dissipationless (independent of the scattering rate), has been keenly debated without experimental resolution.

Yasha Gindikin, V. A. Sablikov

The &#34;effective exponent theory&#34;, developed by Wang, Millis and Das Sarma in [Phys. Rev. B 69, 167101 (2004), Phys. Rev. B 64, 193307 (2001)], fails to calculate correctly the dynamic correlators of Coulomb Luttinger liquid. Main drawbacks are (i) cutting off the Coulomb potential by killing its long-range component, (ii) the absence of non-contradict

Samuel Wehrli, T. M. Rice, Manfred Sigrist

Metallic K3C60 shows pronounced structure and a sharp Fermi edge in integrated photoemission spectra (PES) while the insulating K4C60 and K6C60 phases display only a broad structureless peak. We find that both types of spectra can be explained by the coupling to the optic vibrations of the K+/C60n- ionic lattice. This is suppressed in K3C60 due to metallic s

Olivier Sauret, Denis Feinberg, Thierry Martin

The detailed operation of an electron spin entangler is studied, using density matrix equations. The device is made of a superconductor, two quantum dots and two normal leads. The treatment takes into account coherent tunneling in a non-perturbative way, and analyzes the various parasitic effects, in addition to the main process (crossed Andreev reflection)

Olivier Sauret, Denis Feinberg

The spin resolved current shot noise can uniquely probe the interactions in mesoscopic systems: i) in a normal-superconducting junction, the spin current noise is zero, as carried by singlets, and ii) in a single electron transistor (SET) in the sequential regime, the spin current noise is Poissonian. Coulomb interactions lead to usually repulsive, but also

Akira Onuki, Hikaru Kitamura

A Ginzburg-Landau theory is presented to investigate solvation effects in near-critical polar fluid binary mixtures. Concentration-dependence of the dielectric constant gives rise to a shell region around a charged particle within which solvation occurs preferentially. As the critical point is approached, the concentration has a long-range Ornstein-Zernike t

Urban Lundin, Ross H. McKenzie

Layered systems shows anisotropic transport properties. The interlayer conductivity show a general temperature dependence for a wide class of materials. This can be understood if conduction occurs in two different channels activated at different temperatures. We show that the characteristic temperature dependence can be explained using a polaron model for th

D. Higashiyama, N. Kida, S. Miyasaka, T. Arima

Cross-correlation between magnetic and dielectric properties has been attracting renewed interest because of the fundamental as well as technological importance of controlling the electric (magnetic) polarization by an external magnetic (electric) field. Here, we report the novel phenomenon that an external magnetic field induces and/or modifies ferroelectri

Juyong Park, M. E. J. Newman

We study the family of network models derived by requiring the expected properties of a graph ensemble to match a given set of measurements of a real-world network, while maximizing the entropy of the ensemble. Models of this type play the same role in the study of networks as is played by the Boltzmann distribution in classical statistical mechanics; they o

E. del Barco, A. D. Kent

Here we respond briefly to a comment on our work in arXiv:cond-mat/0405501.

Christophe Texier, Gilles Montambaux

We study the quantum transport in multiterminal networks of quasi-one-dimensional diffusive wires. When calculating the weak localization correction to the conductances, we show that the Cooperon must be properly weighted over each wire. This can even change the sign of the weak localization correction in certain geometries.

G. Baskaran

Superconductivity in an uncompensated boron doped diamond, a very recent observation, is strikingly close to an earlier observation of Anderson-Mott insulator to metal transition, prompting us to suggest an electron correlation driven superconductivity in an impurity band. Random coulomb potential remove a three fold orbital degeneracy of boron acceptor stat

M. T. Mercaldo, J-Ch. Anglès d&#39;Auriac, F. Iglói

The phase transition in the q-state Potts model with homogeneous ferromagnetic couplings is strongly first order for large q, while is rounded in the presence of quenched disorder. Here we study this phenomenon on different two-dimensional lattices by using the fact that the partition function of the model is dominated by a single diagram of the high-tempera

Jesús Pando, Long-Long Feng, Li-Zhi Fang

We investigate the relationship between the mass and velocity fields of the intergalactic medium (IGM) and dark matter. Although the evolution of the IGM is dynamically governed by the gravity of the underlying dark matter field, some statistical properties of the IGM inevitably decouple from those of the dark matter once the nonlinearity of the dynamical eq

Roman Rafikov

We study quasi-static atmospheres of accreting protoplanetary cores for different opacity behaviors and realistic planetesimal accretion rates in various parts of protoplanetary nebula. Atmospheres segregate into those having outer convective zone which smoothly merges with the nebular gas, and those having almost isothermal outer radiative region decoupling

Paul J. Francis, Joss Bland-Hawthorn

The intense UV radiation from a highly luminous QSO should excite fluorescent Ly-alpha emission from any nearby neutral hydrogen clouds. We present a very deep narrow-band search for such emission near the z=2.168 quasar PKS 0424-131, obtained with the Taurus Tunable Filter on the Anglo-Australian Telescope. By working in the UV, at high spectral resolution

Kurt L. Adelberger

Since the photons that stream from QSOs alter the ionization state of the gas they traverse, any changes to a QSO&#39;s luminosity will produce outward-propagating ionization gradients in the surrounding intergalactic gas. This paper shows that at redshift z~3 the gradients will alter the gas&#39;s Lyman-alpha absorption opacity enough to produce a detectabl

Y. Karatas, S. Bilir, S. Karaali, S. G. Ak

We interpret the de-reddened UBV data for the field SA 133 to deduce the stellar density and metallicity distributions function. The logarithmic local space density for giants, $D^{*}(0)=6.40$, and the agreement of the luminosity function for dwarfs and sub-giants with the one of Hipparcos confirms the empirical method used for their separation. The metallic

Tsvi Piran

Gamma-Ray Bursts (GRBs), short and intense pulses of low energy gamma-rays, have fascinated astronomers and astrophysicists since their unexpected discovery in the late sixties. During the last decade, several space missions: BATSE (Burst and Transient Source Experiment) on Compton Gamma-Ray Observatory, BeppoSAX and now HETE II (High-Energy Transient Explor

Lucio Mayer, James Wadsley, Thomas Quinn, Joachim Stadel

We use high resolution 3D SPH simulations to study the evolution of self-gravitating binary protoplanetary disks. Heating by shocks and cooling are included. We consider different orbital separations and masses of the disks and central stars. Isolated massive disks ($M \sim 0.1 M_{ødot}$) fragment into protoplanets as a result of gravitational instability fo

J. Knödlseder, M. Valsesia, M. Allain, S. Boggs

We present first results on the observation of 1809 keV gamma-ray line emission from the Cygnus X region with the SPI imaging spectrometer. Our analysis is based on data from the performance verification phase of the INTEGRAL instruments and comprises 1.3 Ms of exposure time. We observe a 1809 keV line flux of (7.3 +/- 0.9) x 10-5 ph cm-2 s-1 from a region d

H. Ghosh

We analyze the lightcurve of the microlensing event OGLE-2003-BLG-175/MOA-2003-BLG-45 and show that it has two properties that, when combined with future high resolution astrometry, could lead to a direct, accurate measurement of the lens mass. First, the lightcurve shows clear signs of distortion due to the Earth&#39;s accelerated motion, which yields a mea

Douglas A. Swartz, Kajal K. Ghosh, Allyn F. Tennant, Kinwah Wu

One hundred fifty-four discrete non-nuclear Ultra-Luminous X-ray (ULX) sources, with intrinsic X-ray luminosities >1e39 ergs/s, are identified in 82 galaxies observed with Chandra&#39;s Advanced CCD Imaging Spectrometer. Source positions, X-ray luminosities, and spectral and timing characteristics are tabulated. Statistical comparisons between these X-ray pr

Julio F. Navarro

I review the results of recent cosmological simulations of galaxy formation that highlight the importance of satellite accretion in the formation of galactic disks. Tidal debris of disrupted satellites may contribute to the disk component if they are compact enough to survive the decay and circularization of the orbit as dynamical friction brings the satelli

I. Pérez, R. Fux, K. Freeman

This paper presents the dynamical simulations run in the potential derived from the light distribution of 5 late-type barred spiral galaxies. The aim is to determine whether the mass distribution together with the hydrodynamical simulations can reproduce the observed line-of-sight velocity curves and the gas morphology in the inner regions of the sample barr

I. Yusifov, I. Kucuk

We have studied the radial distribution and luminosity function of normal pulsars in the Galaxy, on the basis of the ATNF Pulsar Catalogue where the distances are calculated according to the new electron density model NE2001. We show that the maximum of galactocentric distribution of pulsars located near 3.5 kpc and the scale-length of this distribution is n

V. Stolyarov, M. P. Hobson, A. N. Lasenby, R. B. Barreiro

We present an extension of the harmonic-space maximum-entropy component separation method (MEM) for multi-frequency CMB observations that allows one to perform the separation with more plausible assumptions about the receiver noise and foreground astrophysical components. Component separation is considered in the presence of spatially-varying noise variance

Wilfried Domainko, Myriam Gitti, Sabine Schindler, Wolfgang Kapferer

We study the effect of heating and metal enrichment from supernovae (SNe) residing between galaxies on the Intra-Cluster Medium (ICM). Recent observations indicate that a considerable fraction (~20 %) of the SN Ia parent stellar population in galaxy clusters is intergalactic. By considering their effect on the relaxed progenitors of cooling flow clusters we

S. Zhang, W. Collmar, W. Hermsen, V. Schönfelder

We investigated the MeV properties of 173 unidentified or only tentatively identified EGRET sources listed in the third EGRET catalogue, by analyzing the simultaneously collected COMPTEL MeV data for each individual source. The sources can generally be divided into 4 groups. In this paper we focus on one of these, a group of 22 EGRET sources for which we can

Shuntaro Mizuno, Seung-Joo Lee, Edmund J. Copeland

We study the cosmology of a general scalar field and barotropic fluid during the early stage of a brane-world where the Friedmann constraint is dominated by the square of the energy density. Assuming both the scalar field and fluid are confined to the brane, we find a range of behaviour depending on the form of the potential. Generalising an approach develop

T. Mineo, G. Cusumano, E. Massaro, W. Becker

We report results on the timing and spectral analysis of observations of the millisecond pulsar PSR B1821-24 with RXTE, BeppoSAX and Chandra. The X-ray light curve is characterized by two narrow peaks at a phase distance of 0.452+/-0.002. The average pulsed emission, over the range 1.6-20 keV, is well represented by a single power law with a photon index alp

F. Haberl, C. Motch, V. E. Zavlin, K. Reinsch

We report on the analysis of new X-ray data obtained with XMM-Newton and Chandra from two ROSAT-discovered X-ray dim isolated neutron stars. RX J0806.4-4123 was observed with XMM-Newton in April 2003, 2.5 years after the first observation. The EPIC-pn data confirm that this object is an X-ray pulsar with 11.371 s neutron star spin period. The X-ray spectrum

G. B. Taylor, A. B. Peck, J. S. Ulvestad, C. P. O&#39;Dea

We present Very Long Baseline Array (VLBA) observations of the Gigamaser galaxy TXS2226-184 at 1.3 and 5 GHz. These observations reveal the parsec-scale radio structure of this Seyfert galaxy with exceptionally luminous water maser emission. The source is found to be extended on scales of 10-100 pc with some embedded compact sources, but has no readily ident

J. Rodriguez, Y. Fuchs, D. C. Hannikainen, O. Vilhu

We present the first results of the timing analysis of our RXTE/INTEGRAL monitoring campaign on GRS 1915+105. Over the 6 already performed RXTE observations, we study the presence of Low Frequency QPO (LFQPO), and their energetic dependences. In a view to understand the QPO phenomenon, we compare the QPO properties to the spectral behaviour of the source. We

Lyonell Boulton, Alvaro Restuccia

We study the quantization of the regularized hamiltonian, $H$, of the compactified D=11 supermembrane with non-trivial winding. By showing that $H$ is a relatively small perturbation of the bosonic hamiltonian, we construct a Dyson series for the heat kernel of $H$ and prove its convergence in the topology of the von Neumann-Schatten classes so that $e^{-Ht}

Hsin-Chia Cheng, Ian Low

Little Higgs theories are an attempt to address the little hierarchy problem, i.e., the tension between the naturalness of the electroweak scale and the precision measurements showing no evidence for new physics up to 5-10 TeV. In little Higgs theories, the Higgs mass-squareds are protected to the one-loop order from the quadratic divergence. This allows the

David Berenstein, Sergey A. Cherkis

Beginning with the planar limit of N=4 SYM theory, we study planar diagrams for field theory deformations of N=4 which are marginal at the free field theory level. We show that the requirement of integrability of the full one loop dilatation operator in the scalar sector, places very strong constraints on the field theory, so that the only soluble models cor

Suzanne M. Linder, Robert F. Minchin, Jonathan I. Davies, Maarten Baes

The HIDEEP survey (Minchin et al. 2003) was done in an attempt to find objects having low inferred neutral hydrogen column densities, yet they found a distribution which was strongly peaked at 10^20.65 cm^-2. In an attempt to understand this distribution and similar survey results, we model HI profiles of gas discs and use simple simulations of objects havin

Sean A. Hartnoll, Ruben Portugues

We find explicit probe D3-brane solutions in the infrared of the Maldacena-Nunez background. The solutions describe deformed baryon vertices: q external quarks are separated in spacetime from the remaining N-q. As the separation is taken to infinity we recover known solutions describing infinite confining strings in ${\mathcal{N}}=1$ gauge theory. We present

S. V. Ludkovsky

We investigate superdifferentiability of functions defined on regions of the real octonion (Cayley) algebra and obtain a noncommutative version of the Cauchy-Riemann conditions. Then we study the noncommutative analog of the Cauchy integral as well as criteria for functions of an octonion variable to be analytic. In particular, the octonion exponential and l

Jonathan L. Feng

Cosmology now provides unambiguous, quantitative evidence for new particle physics. I discuss the implications of cosmology for supersymmetry and vice versa. Topics include: motivations for supersymmetry; supersymmetry breaking; dark energy; freeze out and WIMPs; neutralino dark matter; cosmologically preferred regions of minimal supergravity; direct and ind

Hsiao-Wen Chen, Ron Marzke

We have identified six early-type galaxies at z>2.8 in the central 5.76 arcmin^2 Hubble Ultra Deep Field NICMOS region based on a pronounced broad-band discontinuity between the NICMOS F110W and F160W bandpasses. These galaxies have red observed optical and near-infrared colors (AB_F775W - AB_F160W >= 2) that cannot be explained entirely by dust reddening (i

Dan Israel, Costas Kounnas, Domenico Orlando, P. Marios Petropoulos

We analyze asymmetric marginal deformations of SU(2)_k and SL(2,R)_k WZW models. These appear in heterotic string backgrounds with non-vanishing Neveu--Schwarz three-forms plus electric or magnetic fields, depending on whether the deformation is elliptic, hyperbolic or parabolic. Asymmetric deformations create new families of exact string vacua. The geometri

E. Schwegler, G. C. Grossman, F. Gygi, G. Galli

A series of 20 ps ab initio molecular dynamic simulations of water at ambient density and temperatures ranging from 300 to 450K are presented. Both Car-Parrinello (CP) and Born-Oppenheimer (BO) molecular dynamics techniques are compared for systems containing 54 and 64 water molecules. At 300K, excellent agreement is found between radial distribution functio

Francesco Ginelli, Haye Hinrichsen

We propose a mean field theory for interfaces growing according to the Kardar-Parisi-Zhang (KPZ) equation in 1+1 dimensions. The mean field equations are formulated in terms of densities at different heights, taking surface tension and the influence of the nonlinear term in the KPZ equation into account. Although spatial correlations are neglected, the mean

M. Yamaguchi, S. Nomura, D. Sato, T. Akazaki

The photoluminescence (PL) spectra of a two-dimensional electron system induced in a Be-delta-doped GaAs/AlGaAs quantum well (QW) with a back gate are measured. The electron density is controlled from 1 X 10^{9} cm^{-2} to 2.5 X 10^{11} cm^{-2} by changing the back gate voltage. There is a linear increase in the acceptor PL spectrum around 1.49 eV with an in

Yasuhiro Hatsugai

We supply basic tools for the study of the topological order of a multiplet which is an eigenspace of a finite-dimensional normal operator with continuous parameters. We allow intrinsic degeneracies within the multiplet where a well-known standard procedure does not work. As an important example, we give novel expressions for a spin Hall conductance for unit

O. W. Greenberg

We formulate Lorentz covariance of a quantum field theory in terms of covariance of time-ordered products (or other Green&#39;s functions). This formulation of Lorentz covariance implies spacelike local commutativity or anticommutativity of fields, sometimes called microscopic causality or microcausality. With this formulation microcausality does not have to