August 2004 arXiv papers — page 20

T. Christiansen

We study resonances associated to Schrödinger operators with compactly supported potentials on ${\mathbb R}^d$, $d\geq3$, odd. We consider compactly supported potentials depending holomorphically on a complex parameter $z$. For certain such families, for all $z$ except those in a pluripolar set, the associated resonance-counting function has order of growth

Markus Schmidmeier

Let $m$, $n$ be positive integers such that $m\leq n$. We consider all pairs $(B,A)$ where $B$ is a finite dimensional $T^n$-bounded $k[T]$-module and $A$ is a submodule of $B$ which is $T^m$-bounded. They form the objects of the submodule category $S_m(k[T]/T^n)$ which is a Krull-Schmidt category with Auslander-Reiten sequences. The case $m=n$ deals with su

Michel Brion, Jesper Funch Thomsen

Let G denote a connected reductive algebraic group over an algebraically closed field k and let X denote a projective G x G-equivariant embedding of G. The large Schubert varieties in X are the closures of the double cosets BgB, where B denotes a Borel subgroup of G, and g is in G. We prove that these varieties are globally F-regular in positive characterist

Daniel C. Isaksen

We present a closed model structure for the category of pro-spectra in which the weak equivalences are detected by stable homotopy pro-groups. With some bounded-below assumptions, weak equivalences are also detected by cohomology as in the classical Whitehead theorem for spectra. We establish an Atiyah-Hirzebruch spectral sequence in this context, which make

Lars Bruenjes, Christian Serpe

In order to apply nonstandard methods to modern algebraic geometry, as a first step in this paper we study the applications of nonstandard constructions to category theory. It turns out that many categorial properties are well behaved under enlargements.

Jacob van den Berg, Olle Haggstrom, Jeff Kahn

Consider ordinary bond percolation on a finite or countably infinite graph. Let s, t, a and b be vertices. An earlier paper proved the (nonintuitive) result that, conditioned on the event that there is no open path from s to t, the two events "there is an open path from s to a" and "there is an open path from s to b" are positively correlated

Yoonweon Lee

Given two unitary involutions $σ_{1}$ and $σ_{2}$ satisfying $G σ_{i} = - σ_{i} G$ on $ker B$ on a compact manifold with cylindrical end, M. Lesch, K. Wojciechowski ([LW]) and W. Müller ([M]) established the formula describing the difference of two eta-invariants with the APS boundary conditions associated with $σ_{1}$ and $σ_{2}$. In this paper we establish

Henry Cohn, Abhinav Kumar

In this research announcement we outline the methods used in our recent proof that the Leech lattice is the unique densest lattice in R^24. Complete details will appear elsewhere, but here we illustrate our techniques by applying them to the case of lattice packings in R^2, and we discuss the obstacles that arise in higher dimensions.

Ettore Aldrovandi

We introduce a model for Hermitian holormorphic Deligne cohomology on a projective algebraic manifold which allows to incorporate singular hermitian structures along a normal crossing divisor. In the case of a projective curve, the cup-product in cohomology is shown to correspond to a generalization of the Deligne pairing to line bundles with "good"

Rami Kanhouche

A factorization of the inverse of a Hermetian positive definite matrix based on a diagonal by diagonal recurrence formulae permits the inversion of Toeplitz Block Toeplitz matrices using minimized matrix-vector products, with a complexity of ((n1)^3)((n2)^2), where n1 is the block size, and n2 is the block matrix size. A 2D levinson algorithm is introduced t

Carlos Gutierrez, Roland Rabanal

(a) Let X=(f,g) be a differentiable map in the plane (not necessarily C^1) and let Spec(X) be the set of (complex) eigenvalues of the derivative DX(p) when p varies in R^2. If, for some ε>0, the set Spec(X) is disjoint of [0,ε) then X is injective. (b) Let X be a differentiable vector field such that X(0)=0 and $Re(z)< 0$ for all z in Spec(X). Then, for all

Ivan Smith

We apply ideas from conformal field theory to study symplectic four-manifolds, by using modular functors to &#34;linearise&#34; Lefschetz fibrations. In Chern-Simons theory this leads to the study of parabolic vector bundles of conformal blocks. Motivated by the Hard Lefschetz theorem, we show the bundles of SU(2) conformal blocks associated to Kaehler surfa

Richard Arratia, Bela Bollobas, Gregory B. Sorkin

We introduce a new graph polynomial in two variables. This ``interlace&#39;&#39; polynomial can be computed in two very different ways. The first is an expansion analogous to the state space expansion of the Tutte polynomial; the significant differences are that our expansion is over vertex rather than edge subsets, and the rank and nullity employed are thos

Richard Arratia, Bela Bollobas, Gregory B. Sorkin

Motivated by circle graphs, and the enumeration of Euler circuits, we define a one-variable ``interlace polynomial&#39;&#39; for any graph. The polynomial satisfies a beautiful and unexpected reduction relation, quite different from the cut and fuse reduction characterizing the Tutte polynomial. It emerges that the interlace graph polynomial may be viewed as

J. L. Boldo, C. P. Constantinidis, F. Gieres, M. Lefrançois

Observables of topological Yang-Mills theory were defined by Witten as the classes of an equivariant cohomology. We propose to define them alternatively as the BRST cohomology classes of a superspace version of the theory, where BRST invariance is associated to super Yang-Mills invariance. We provide and discuss the general solution of this cohomology.

John Campbell, R. K. Ellis, Francesco Tramontano

We present the results of a next-to-leading order analysis of single top production including the decay of the top quark. Radiative effects are included both in the production and decay stages, using a general subtraction method. This calculation gives a good treatment of the jet activity associated with single top production. We perform an analysis of the s

T. Blazek, S. F. King

We suggest that $e\to μ$ conversion in low-energy electron-nucleus scattering is a new and potentially observable indirect signal of supersymmetry and should be searched for in experiment. We estimate the rate for this process in a straightforward calculation taking into account the existing constraint from non-observation of the $μ\to eγ$ decay and find the

Qaisar Shafi, Zurab Tavartkiladze

Within the MSSM framework and with purely anomaly mediated supersymmetry breaking the slepton masses turn out to be tachyonic. We resolve this problem by introducing an anomaly free U(1) gauge symmetry which provides positive $D$-term contributions to sparticle masses squared that are flavor conserving at one loop. Two realistic examples based on SU(5) are p

D. S. Hwang, D. W. Kim

The resonance D*_sJ (2317) which is considered to be the 1^3P_0 state composed of charm and strange quarks has been discovered recently. The measured mass, which is about 160 MeV lower than the mass of the 1^3P_0 state obtained from the potential model calculation by Godfrey and Isgur, was considered surprisingly low and attracted a lot of theoretical invest

Wei-Shu Hou, Makiko Nagashima

The experimental observation of sizable transverse components for B-> phi K^* decay is in strong contrast to all other VV modes, and poses a challenge to our understanding of B decay dynamics. Observing that the gluon emitted from b-> sg^{(*)} chromodipole transition is transverse, we give a heuristic model where the transverse phi descends from the emitted

M. Klasen, G. Kramer

We have calculated the diffractive dijet cross section in low-Q^2 ep scattering in the HERA regime. The results of the calculation in LO and NLO are compared to recent experimental data of the H1 collaboration. We find that in LO the calculated cross sections are in reasonable agreement with the experimental results. In NLO, however, some of the cross sectio

The BABAR Collaboration, B. Aubert

We present measurements of branching fractions for four previously unobserved B-meson decays with an eta or eta&#39; meson in the final state. The data sample corresponds to 182 million B-Bbar pairs produced from e+e- annihilation at the Upsilon(4S) resonance. We measure the following branching fractions in units of 10^-6: BF(B0 -> eta omega) = 1.2 +/- 0.6 +

B. Aubert, BABAR Collaboration

We have analyzed 116 fb^-1 of data collected by the BABAR detector for Xic0 production. In this paper we describe the observation of Xic0 production from ccbar continuum and from B decays, with the Xic0 decaying into (Xi- pi+) and (Omega- K+) modes. The ratio of the branching fractions of the Xic0 decays into these two final states measured in the ccbar cont

B. I. Eisenstein, CLEO Collaboration

Using nearly 60 pb-1 of data collected with the CLEO-c detector at the psi_prime resonance, we measure absolute branching fractions for three D0 and two D+ Cabibbo-allowed hadronic decay modes, and the cross section for e+e- to D Dbar at Ecm = 3.77 GeV. We report preliminary measurements of the reference branching fractions, B(D0 to K- pi+) = (3.92\pm 0.08\p

NA48 Collaboration

Using data taken during the year 2000 with the NA48 detector at the CERN SPS, a search for the CP violating decay K_S -> 3 pi0 has been performed. From a fit to the lifetime distribution of about 4.9 million reconstructed K0/K0bar -> 3 pi0 decays, the CP violating amplitude eta_000 = A(K_S -> 3 pi0)/A(K_L -> 3 pi0) has been found to be Re(eta_000) = -0.002 +

B. Aubert, BABAR Collaboration

We present a study of the decays B0bar --> D(*)0 K(*)0bar using a sample of 124 million Upsilon(4S) --> B0bar B0 decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We report evidence for the decay of B0 and B0bar mesons to the D*0 K_S final state with an average branching fraction BF(B --> D*0 K0bar) = (4.5 +/- 1.

B. Aubert, BABAR Collaboration

A preliminary measurement of the branching fraction of the tau- -> 3h-2h+nu decay (h= pi, K$) with the BaBar detector is found to be {8.52 +/- 0.09 +/- 0.40} x 10E-4, where the first error is statistical and the second is systematic. The data show evidence that the rho resonance plays a strong role in the decay of the tau lepton to five charged hadrons.

Sebastian Schaetzel

Measurements of hard diffractive final states performed with the H1 experiment at HERA are presented and confronted with leading order and next-to-leading order QCD predictions based on diffractive parton densities to test QCD factorisation in diffraction

B Collaboration, I. Abt

We have searched for Theta^+(1540) and Xi^{--}(1862) pentaquark candidates in proton-induced reactions on C, Ti and W targets at mid-rapidity and \sqrt{s} = 41.6 GeV. In 2x10^8 inelastic events we find no evidence for narrow (sigma~5 MeV) signals in the Theta^+ -> pK_s and Xi^{--} -> Xi^-pi^- channels; our 95% CL upper limits (UL) for the inclusive productio

BES Collaboration, M. Ablikim

\pspto ρπis observed for the fisrt time in a data sample of 14M \psp decays collected by the BESII detector at BEPC. The branching fraction is measured to be \BR(psptoρπ)=(5.1+-0.7+-0.8)10-5, where the first error is statistical and the second one is systematic. A high mass excited ρstate wirh mass around 2.15GeV/c2 is also observed wirh \BR(pspto ρ(2150)π)

M. Ablikim

K_S K_L from psi&#39;&#39; decays is searched for using the psi&#39;&#39; data collected by BESII at BEPC, the upper limit of the branching fraction is determined to be B(psi&#39;&#39;--> K_S K_L) < 2.1\times 10^{-4} at 90% C. L. The measurement is compared with the prediction of the S- and D-wave mixing model of the charmonia, based on the measurements of t

Christian Cherubini, Donato Bini, Marco Bruni, Zoltan Perjes

The speciality index, which has been mainly used in Numerical Relativity for studying gravitational waves phenomena as an indicator of the special or non-special Petrov type character of a spacetime, is applied here in the context of Mixmaster cosmology, using the Belinski-Khalatnikov-Lifshitz map. Possible applications for the associated chaotic dynamics ar

Jason Cantarella, Michael Piatek

The solution of large, sparse constrained least-squares problems is a staple in scientific and engineering applications. However, currently available codes for such problems are proprietary or based on MATLAB. We announce a freely available C implementation of the fast block pivoting algorithm of Portugal, Judice, and Vicente. Our version is several times fa

Shengdong Li, Zhen Yu, Christopher Rutherglen, Peter J. Burke

Centimeter scale aligned carbon nanotube arrays are grown from nanoparticle metal catalyst pads. We find the nanotubes grow both with and against the wind. A metal underlayer provides in-situ electrical contact to these long nanotubes with no post growth processing needed. Using the electrically contacted nanotubes, we study electrical transport of 0.4 cm lo

Albert C. Pan, David Chandler

Reactive pathways to nucleation in a three-dimensional Ising model at 60% of the critical temperature are studied using transition path sampling of single spin flip Monte Carlo dynamics. Analysis of the transition state ensemble (TSE) indicates that the critical nuclei are rough and anisotropic. The TSE, projected onto the free energy surface characterized b

Michael C. Mackey, Marta Tyran-Kaminska

Here we review and extend central limit theorems for highly chaotic but deterministic semi-dynamical discrete time systems. We then apply these results show how Brownian motion-like results are recovered, and how an Ornstein-Uhlenbeck process results within a totally deterministic framework. These results illustrate that the contamination of experimental dat

Cristina Bena, Steven A. Kivelson

We determine the effect of quasiparticle interference on the spatial variations of the local density of states (LDOS) in graphite in the neighborhood of an isolated impurity. A number of characteristic behaviors of interference are identified in the Fourier transformed spectrum. A comparison between our results and scanning tunneling microscopy (STM) experim

R. H. He, X. F. Jin

A prototype Hamiltonian for the generic patterned magnetic structures, of dipolar interaction with perpendicular anisotropy, is investigated within the finite-size framework by Landau-Lifshift-Gilbert classical spin dynamics. Modifications on the ground state phase diagram are discussed with an emphasis on the disappearance of continuous degeneracy in the gr

Kazumoto Iguchi, Hiroaki Yamada

We study vibrational modes and spectrum of a model system of atoms and springs on a scale-free network in order to understand the nature of excitations with many degrees of freedom on the scale-free network. We assume that the atoms and springs are distributed as nodes and links of a scale-free network, assigning the mass $M_{i}$ and the specific oscillation

Carsten T. Rieck, Kurt Scharnberg, Simon Scheffler

It has long been established that disorder has profound effects on unconventional superconductors and it has been suggested repeatedly that observation and analysis of these disorder effects can help to identify the order parameter symmetry. In much of the relevant literature, including very sophisticated calculations of interference and weak localization ef

Supriyo Datta

This tutorial article presents a &#34;bottom-up&#34; view of electrical resistance starting from something really small, like a molecule, and then discussing the issues that arises as we move to bigger conductors. Remarkably, no serious quantum mechanics is needed to understand electrical conduction through something really small, except for unusual things l

Jikeun Seo, Hye-Young Kim, J. -S. Kim

Kinetic Monte Carlo simulation in conjunction with molecular dynamics simulation is utilized to study the effect of the steered deposition on the growth of Cu on Cu(1,1,17). It is found that the deposition flux becomes inhomogeneous in step train direction and the inhomogeneity depends on the deposition angle, when the deposition is made along that direction

Armen E. Allahverdyan, Roger Balian, Theo M. Nieuwenhuizen

An exactly solvable model for a quantum measurement is discussed which is governed by hamiltonian quantum dynamics. The $z$-component $\hat s_z$ of a spin-1/2 is measured with an apparatus, which itself consists of magnet coupled to a bath. The initial state of the magnet is a metastable paramagnet, while the bath starts in a thermal, gibbsian state. Conditi

Arkady I. Leonov

A thermodynamically related model is developed for describing elastic rubber-like behavior of amorphous and crystallizing polymers and demonstrated on example of simple extension. Both the &#8220;entropic&#8221; and &#8220;energetic&#8221; motions of polymer chains that contribute in macroscopic elastic deformation are taken into account. The model displays

M. Nicklas, G. Sparn, R. Lackner, E. Bauer

We studied the evolution of superconductivity (sc) and antiferromagnetism (afm) in the heavy fermion compound CePt_3Si with hydrostatic pressure. We present a pressure-temperature phase diagram established by electrical transport measurements. Pressure shifts the superconducting transition temperature, T_c, to lower temperatures. Antiferromagnetism is suppre

N. Kikugawa, A. P. Mackenzie, C. Bergemann, Y. Maeno

We report the results of a study of the Hall effect and magnetoresistance in single crystals of Sr2RuO4 in which Sr^(2+) has been substituted by La^(3+) (Sr(2-y)La(y)RuO(4)) or Ru^(4+) by Ti^(4+) (Sr(2)Ru(1-x)Ti(x)O(4)). For undoped Sr2RuO4, the purity is so high that the strong-field Hall coefficient can be measured for fields above 4 T. The conventional we

J. Stahn, J. Chakhalian, C. Niedermayer, J. Hoppler

$\mathrm{YBa_2Cu_3O_7/La_{2/3}Ca_{1/3}MnO_3}$ superconducting/ferromagnetic (SC/FM) multilayers have been studied by neutron reflectometry. Evidence for a characteristic difference between the structural and magnetic depth profiles is obtained from the occurrence of a structurally forbidden Bragg peak in the FM state. The comparison with simulated reflectivi

J. Krawczyk, A. L. Owczarek, T. Prellberg, A. Rechnitzer

An infinite hierarchy of layering transitions exists for model polymers in solution under poor solvent or low temperatures and near an attractive surface. A flat histogram stochastic growth algorithm known as FlatPERM has been used on a self- and surface interacting self-avoiding walk model for lengths up to 256. The associated phases exist as stable equilib

Ranber Singh, S. Prakash, Nitya Nath Shukla, R. Prasad

The sample dependence of various properties of hydrogenated amorphous silicon ($a$-Si:H) have been studied with 216 silicon atoms and 24 hydrogen atoms using the density functional based tight binding molecular dynamics simulations. The Si-Si and Si-H pair correlation functions are independent of preparation procedure as well as initial conditions, the H-H p

J. Yang, W. H. Song, Y. Q. Ma, R. L. Zhang

The effect of Pr-doping on structural, magnetic and transport properties in electron-doped manganites La0.9-xPrxTe0.1MnO3 with fixed carrier concentration are investigated. The room temperature structural transition from rhombohedral (R3C) to orthorhombic (Pbnm) symmetry is found in the samples with by the Rietveld refinement of x-ray powder diffraction patt

J. Yang, W. H. Song, Y. Q. Ma, R. L. Zhang

The structural, electrical transport and magnetic properties of perovskite oxides La1-xTexMnO3 have been investigated and thus the magnetic phase diagram of La1-xTexMnO3 compounds as a function of temperature and the doping level x has been obtained. All samples have rhombohedral structure and undergo paramagnetic-ferromagnetic (PM-FM) transition accompanied

Xiangyun Qiu, Th. Proffen, J. F. Mitchell, S. J. L. Billinge

The local and intermediate structure of stoichiometric LaMnO$_3$ has been studied in the pseudocubic and rhombohedral phases at high temperatures (300 to 1150 K). Neutron powder diffraction data were collected and a combined Rietveld and high real space resolution atomic pair distribution function analysis carried out. The nature of the Jahn-Teller (JT) tran

J. Yang, W. H. Song, R. L. Zhang, Y. Q. Ma

The effect of the variation of oxygen content on structural, magnetic and transport properties in the electron-doped manganites La0.9Te0.1MnOy has been investigated. All samples show a rhombohedral structure with the space group . The Curie temperature decreases and the paramagnetic-ferromagnetic (PM-FM) transition becomes broader with the reduction of oxyge

Kenji Yonemitsu

In order to study consequences of the differences between the ionic-to-neutral and neutral-to-ionic transitions in the one-dimensional extended Peierls-Hubbard model with alternating potentials for the TTF-CA complex, we introduce a double pulse of oscillating electric field in the time-dependent Schrödinger equation and vary the interval between the two pul

Kenji Yonemitsu

Dynamics of charge density and lattice displacements after the neutral phase is photoexcited is studied by solving the time-dependent Schrödinger equation for a one-dimensional extended Peierls-Hubbard model with alternating potentials. In contrast to the ionic-to-neutral transition studied previously, the neutral-to-ionic transition proceeds in an uncoopera

Kenji Yonemitsu

Photoinduced dynamics of charge density and lattice displacements is calculated by solving the time-dependent Schrödinger equation for a one-dimensional extended Peierls-Hubbard model with alternating potentials for the mixed-stack organic charge-transfer complex, TTF-CA. A pulse of oscillating electric field is incorporated into the Peierls phase of the tra

M. Huecker, Young-June Kim, G. D. Gu, B. D. Gaulin

We present neutron scattering data on two single crystals of the high temperature superconductor La2-x(Ca,Sr)xCaCu2O6+delta. The Ca0.1-doped crystal exhibits a long-range antiferromagnetically ordered ground state. In contrast, the Sr0.15-doped crystal exhibits short-range antiferromagnetic order as well as weak superconductivity. In both crystals antiferrom

E. M. Dizhur, A. V. Fedorov

An alternative approach to detect very weak singularities on the characteristics of a tunnel diode is proposed in which the numerical differential filtering is applied directly to measured current versus voltage dependence instead of the modulation technique commonly used with this purpose. The gains and looses of the both approaches in the particular case o

C. Farrell, U. Leonhardt

We discuss how the Perfectly Matched Layer (PML) can be adapted to numerical simulations of nonlinear and matter wave systems, such as Bose-Einstein condensates. We also present some examples which illustrate the benefits of using the PML in the simulation of nonlinear and matter waves.

T. Nikuni, J. E. Williams

We derive a kinetic theory for a spin-1/2 Bose-condensed gas of two-level atoms at finite temperatures. The condensate dynamics is described by a generalized Gross-Pitaevskii equation for the two-component spinor order parameter, which includes the interaction with the uncondensed fraction. The noncondensate atoms are described by a quantum kinetic equation,

S. Wachter, S. Patel, C. Kouveliotou, P. Bouchet

We present precise localizations of AXP 1E1841-045 and SGR 1627-41 with Chandra. We obtained new infrared observations of SGR 1627-41 and reanalyzed archival observations of AXP 1E1841-045 in order to refine their positions and search for infrared counterparts. A faint source is detected inside the error circle of AXP 1E1841-045. In the case of SGR 1627-41,

Leo Blitz, Erik Rosolowsky

We present a complete map of the Giant Molecular Clouds in M33 and show that they lie exclusively on filaments of HI. The GMCs are localized on the extended HI filaments, and HI filaments extend well beyond the radius where the GMCs are found, suggesting that the H_2 forms from the HI and not vice-versa. We propose that the fraction of neutral gas that is mo

Charles W. Danforth, J. Michael Shull

Intergalactic absorbers along lines of sight to distant quasars are a powerful diagnostic for the evolution and content of the IGM. In this study, we search known low-z Ly-alpha absorption systems for equivalent absorption in higher Lyman lines as well as the important metal ions OVI and CIII. OVI absorption is detected roughly half the time and shows a smal

Lev Titarchuk, Chris Shrader

A number of recent lines of evidence point towards the presence of hot, out-flowing plasma from the central regions of compact Galactic and extragalactic X-ray sources. Additionally, it has long been noted that many of these sources exhibit an ``excess&#39;&#39; continuum component, above 10 keV, usually attributed to Compton Reflection from a static medium.

E. Muller, S. Stanimirovic, E. Rosolowsky, L. Staveley-Smith

We present results from two statistical analyses applied to an neutral hydrogen (HI) dataset of the nearby tidal bridge in the Magellanic System. Primarily, analyses of the Spatial Power Spectrum suggest that the Magellanic Bridge, historically considered to be a single contiguous feature, may in fact be a projection of two kinematically and morphologically

S. Molkov, M. Revnivtsev, A. Lutovinov, R. Sunyaev

We present results of analysis of a bursting behavior of a low mass X-ray binary system SLX 1735-269 during INTEGRAL observations of the Galactic Center region in 2003. There were detected 6 type I X-ray bursts in total, with one being much longer and more powerful then others. A strong dependence of the bursts recurrence time on the mass accretion rate is o

Gerry Gilmore

GAIA will provide a multi-colour photometric and astrometric census of some one billion compact sources, complete to 20th magnitude. In addition, spectra for radial velocities will be obtained for about 30 million stars brighter than V=17. The high spatial resolution and astrometric precision, 0.1arcsec and 10microarcsec to V=15, will not only quantify the d

T. Nagao, Y. Taniguchi, N. Kashikawa, K. Kodaira

We report on the discovery of a star-forming galaxy at z=6.33 in the Subaru Deep Field. This object is selected as a candidate of an i&#39;-dropout, high-redshift galaxy around z=6 because of its red i&#39;-z&#39; color in our deep optical imaging survey in the Subaru Deep Field. Our follow up optical spectroscopy reveals that this object is a strong Ly-alph

Tohru Nagao, Koji S. Kawabata, Takashi Murayama, Youichi Ohyama

We report on the result of our high quality spectropolarimetric observation for the narrow-line region in a nearby Seyfert 2 galaxy, Mrk 573, by the Subaru Telescope. The polarized flux spectrum of Mrk 573 shows not only prominent scattered broad H$α$ emission but also various narrow forbidden emission lines. We find that the measured polarization degree of

M. De Becker, G. Rauw

We present the very first analysis of the spectroscopic variability of the three rapidly rotating Oef stars HD192281 (O5(ef)), HD14442 (O5.5ef) and HD14434 (O6.5(ef)). Radial velocities of the HeII lambda 4541 line reveal no evidence of binarity on time scales of a few days, or from one year to the next, for any of the targets. The HeII lambda 4686 double-pe

Kerttu Viironen, Juri Poutanen

We study theoretical X-ray light curves and polarization properties of accretion-powered millisecond pulsars. We assume that the radiation is produced in two antipodal spots at the neutron star surface which are associated with the magnetic poles. We compute the angle-dependent intensity and polarization produced in an electron-scattering dominated plane-par

C. Esteban, M. Peimbert, J. Garcia-Rojas, M. T. Ruiz

We present VLT UVES echelle spectrophotometry of the Orion nebula in the 3100 to 10400 A range. We have measured the intensity of 555 emission lines, many of them corresponding to permitted lines of different heavy-element ions. This is the largest set of spectral emission lines ever obtained for a Galactic or extragalactic HII region. We have derived He+, C

G. Helou, H. Roussel, P. Appleton, D. Frayer

The Spitzer Space Telescope was used to study the mid-infrared to far-infrared properties of NGC 300, and to compare dust emission to Halpha to elucidate the heating of the ISM and the star formation cycle at scales < 100 pc. The new data allow us to discern clear differences in the spatial distribution of 8 micron dust emission with respect to 24 micron dus

Vassiliki Kalogera, Chunglee Kim, Duncan R. Lorimer, Mia Ihm

In this paper we consider the population of eccentric binaries with a neutron star and a white dwarf that has been revealed in our galaxy in recent years through binary pulsar observations. We apply our statistical analysis method (Kim, Kalogera, & Lorimer 2003)and calculate the Galactic formation rate of these binaries empirically. We then compare our resul

Inma Martinez-Valpuesta, Isaac Shlosman

Young stellar bars in disk galaxies experience a vertical buckling instability which terminates their growth and thickens them, resulting in a characteristic peanut/boxy shape when viewed edge on. Using N-body simulations of galactic disks embedded in live halos, we have analyzed the bar structure throughout this instability and found that the outer third of

N. Tominaga, J. Deng, P. A. Mazzali, K. Maeda

XRF 030723 is the first X-ray flash (XRF) to show in its optical light curve (LC) a bump that has been interpreted as the signature of a supernova (SN). After subtracting the afterglow component from the observed optical LC of the XRF counterpart, the properties of the putative SN are constrained by means of synthetic LCs of core-collapse SNe. For the redshi

J. Raufeisen, S. J. Brodsky

Light-front quantization has important advantages for describing relativistic statistical systems, particularly systems for which boost invariance is essential, such as the fireball created in a heavy ion collisions. In this paper we develop light-front field theory at finite temperature and density with special attention to quantum chromodynamics. We constr

Arthur Lue, Glenn D. Starkman

Observations exploring the contemporary cosmic acceleration have sparked interest in dark energy models possessing equations of state with w < -1. We review how the cosmic expansion history of a Dvali-Gabadadze-Porrati (DGP) braneworld model with a standard brane cosmological constant can mimic that of ordinary 4-dimensional gravity with w < -1 &#34;phantom&

Shirley Ho, Martin White

We study the strong gravitational lensing properties of galaxy clusters obtained from N-body simulations with standard $Λ$CDM cosmology. We have used the 32 most massive clusters from a simulation at various redshifts and ray-traced through the clusters to investigate the giant arcs statistics. We have investigated the prevalence of multiple arc system, by l

E. Almaas, P. L. Krapivsky, S. Redner

We study the statistics of growing networks in which each link carries a weight (k_i k_j)^theta, where k_i and k_j are the node degrees at the endpoints of link ij. Network growth is governed by preferential attachment in which a newly-added node attaches to a node of degree k with rate A_k=k+lambda. For general values of theta and lambda, we compute the tot

B. L. Ioffe, A. G. Oganesian

It is shown, that if the pentaquark $Θ^+ = uudd\bar{s}$ baryon can be represented by the local quark current $η_Θ$, its decay $Θ^+ \to n K^+ (p K^0)$ is forbidden in the limit of chirality conservation. The $Θ^+$decay width $Γ$ is proportional to $α^2_s < 0 | \bar{q} q | 0 >^2$, where $<0 | \bar{q} q | 0 >$, $q = u,d,s$ is quark condensate, and, therefore, i

Friedel Epple

We establish Einstein-Hilbert gravity couplings in the effective action for Intersecting Brane Worlds. The four-dimensional induced Planck mass is determined by calculating graviton scattering amplitudes at one-loop in the string perturbation expansion. We derive a general formula linking the induced Planck mass for N=1 supersymmetric backgrounds directly to

A. C. D. van Enter, K. Netocny, H. G. Schaap

The infinite-volume limit behavior of the 2d Ising model under possibly strong random boundary conditions is studied. The model exhibits chaotic size-dependence at low temperatures and we prove that the `+&#39; and `-&#39; phases are the only almost sure limit Gibbs measures, assuming that the limit is taken along a sparse enough sequence of squares. In part

Przemyslaw Repetowicz, Brian Lucey, Peter Richmond

We consider a generalization of the Heath Jarrow Morton model for the term structure of interest rates where the forward rate is driven by Paretian fluctuations. We derive a generalization of Itô&#39;s lemma for the calculation of a differential of a Paretian stochastic variable and use it to derive a Stochastic Differential Equation for the discounted bond

Pearl J. Y. Louis, Elena A. Ostrovskaya, Yuri S. Kivshar

We present a numerical study of dispersion manipulation and formation of matter-wave gap solitons in a Bose-Einstein condensate trapped in an optical superlattice. We demonstrate a method for controlled generation of matter-wave gap solitons in a stationary lattice by using an interference pattern of two condensate wavepackets, which mimics the structure of

Philip D. Mannheim, Aharon Davidson

As a model, the Pais-Uhlenbeck fourth order oscillator with equation of motion $d^4q/dt^4+(ω_1^2+ω_2^2)d^2q/dt^2 +ω_1^2ω_2^2 q=0$ is a quantum-mechanical prototype of a field theory containing both second and fourth order derivative terms. With its dynamical degrees of freedom obeying constraints due to the presence of higher order time derivatives, the mode

Aline Lopes Balladares, Marcia C. Barbosa

A two dimensional lattice gas model with &#39;&#39;core-softened&#39;&#39; potential is investigated. Two liquid phases and density anomaly are found. The demixing phase transition between the two liquid phases end at a tricritical point that is also the terminus of a critical line. The density anomaly is related to this continuous line.

A. De Martino, M. Thorwart, R. Egger, R. Graham

We study one-dimensional incommensurate bosons with strong repulsive interactions and weak disorder. In analogy to the clean Tonks-Girardeau gas, a Bose-Fermi mapping expresses this problem in terms of disordered free fermions. Thereby many known results apply, in particular for the density-density correlations, the distribution function of the local density

J. M. Murray, S. N. Pisharody, H. Wen, P. H. Bucksbaum

A kick from a unipolar half-cycle pulse (HCP) can redistribute population and shift the relative phase between states in a radial Rydberg wave packet. We have measured the quantum coherence properties following the kick, and show that selected coherences can be destroyed by applying an HCP at specific times. Quantum mechanical simulations show that this is d

Christian Korff

The spectra of previously constructed auxiliary matrices for the six-vertex model at roots of unity are investigated for spin-chains of even and odd length. The two cases show remarkable differences. In particular, it is shown that for even roots of unity and an odd number of sites the eigenvalues contain two linear independent solutions to Baxter&#39;s TQ-e

S. Dubinsky, A. Korchin, N. Merenkov, G. Pancheri

The process of $e^+ e^-$ annihilation into $π^+ π^-$ pair with radiation of the photon is considered. The amplitude of the reaction $e^+ e^- \to π^+ π^- γ$ consists of the model independent initial-state radiation (ISR) and model dependent final-state radiation (FSR). The general structure of the FSR tensor is constructed from Lorentz covariance, gauge invar

C. M. Zhang, H. X. Yin, Y. H. Zhao, H. K. Chang

In this paper, we improve the previous work on the MHD Alfven wave oscillation model for the neutron star (NS) kHz quasi-periodic oscillations (QPOs), and compare the model with the updated twin kHz QPO data. For the 17 NS X-ray sources with the simultaneously detected twin kHz QPO frequencies, the stellar mass M and radius R constraints are given by means o

A. Athenodorou, H. Panagopoulos

We calculate the 2-loop partition function of QCD on the lattice, using the Wilson formulation for gluons and the overlap-Dirac operator for fermions. Direct by-products of our result are the 2-loop free energy and average plaquette. Our calculation serves also as a prototype for further higher loop calculations in the overlap formalism. We present our resul

Bhavtosh Bansal, Rituparna Ghosh, V. Venkataraman

The scattering of carriers by charged dislocations in semiconductors is studied within the framework of the linearized Boltzmann transport theory with an emphasis on examining consequences of the extreme anisotropy of the scattering potential. A new closed-form approximate expression for the carrier mobility valid for all temperatures is proposed. The ratios

A. P. Majtey, P. W. Lamberti, M. T. Martin, A. Plastino

The notion of distinguishability between quantum states has shown to be fundamental in the frame of quantum information theory. In this paper we present a new distinguishability criterium by using a information theoretic quantity: the Jensen-Shannon divergence (JSD). This quantity has several interesting properties, both from a conceptual and a formal point

N. Tagg, A. De Santo, A. Weber, A. Cabrera

Hamamatsu R5900-00-M64 and R7600-00-M64 photomultiplier tubes will be used with wavelength--shifting optical fibres to read out scintillator strips in the MINOS near detector. We report on measurements of the gain, efficiency, linearity, crosstalk, and dark noise of 232 of these PMTs, of which 219 met MINOS requirements.

L. Maiani, F. Piccinini, A. D. Polosa, V. Riquer

Using the methods introduced in a previous paper, we consider the dissociation of J/psi by the lowest-lying pseudoscalar and vector mesons in the hadronic fireball formed in heavy ion collisions, assumed to be a hadron gas at temperature T. Absorption by nuclear matter is accounted for as well. We compare with the S-U and Pb-Pb data presented by the NA50 Col

Toby Gee

We show that if F is a totally real field in which p splits completely and f is a mod p Hilbert modular form with parallel weight 2<k<p, which is totally ordinary at p and has tamely ramified Galois representation at all primes dividing p, then there is a &#34;companion form&#34; of parallel weight k&#39;:=p+1-k. This work generalises results of Gross and Co

W. Roberts

We examine cross sections for the processes $γN\to NK\bar{K}$ in the framework of a phenomenological Lagrangian. We include contributions from $Λ$ and $Σ$ resonances up to spin 3/2, as well as those from an exotic $Θ^+$. We allow the $Θ^+$ to have spin 1/2 or 3/2, with either positive or negative parity in each case. We also allow the state to be either isov

Moumita Das, Buddhapriya Chakrabarti, Chandan Dasgupta, Sriram Ramaswamy

With a view to understanding the ``rheochaos&#39;&#39; observed in recent experiments in a variety of orientable fluids, we study numerically the equations of motion of the spatiotemporal evolution of the traceless symmetric order parameter of a sheared nematogenic fluid. In particular we establish, by decisive numerical tests, that the irregular oscillatory