February 2001 arXiv papers — page 16

Marcin Sawicki

A 2-hour service-mode SCUBA observation of the gravitationally-lensed Lyman break galaxy MS1512-cB58 resulted in a 3 sigma upper limit of 3.9 mJy at 850um. A comparison of this upper limit with values expected from rest-UV/optical measurements of extiction suggests that dust temperature (T_d) and/or emissivity index (beta) in cB58 may be substantially higher

I. V. Moskalenko, E. R. Christian, A. A. Moiseev, J. F. Ormes

Most cosmic ray antiprotons observed near the Earth are secondaries produced in collisions of energetic cosmic ray (CR) particles with interstellar gas. The spectrum of secondary antiprotons is expected to peak at ~2 GeV and decrease sharply at lower energies. This leaves a low energy window in which to look for signatures of exotic processes such as evapora

K. D. Kuntz, S. L. Snowden

Using stellar luminosity functions derived from ROSAT data, the contributions of Galactic stars to the diffuse X-ray background are calculated for ROSAT PSPC energy bands. The model follows that of Guillout et al. (1996), but uses ROSAT rather than {\it Einstein} data to determine the intrinsic luminosity distributions. The model adequately predicts the numb

Matias Zaldarriaga

We propose a statistical method to search for fluctuations in the temperature of the intergalactic medium (IGM) using the Lyman $α$ forest. The power on small scales ($\sim 25 \km/\s$) is used as a thermometer and fluctuations of this power are constrained. The method is illustrated using Q1422+231. We see no evidence of temperature fluctuations. We show tha

Thomas Toniazzo, Sabine Schindler

Detailed 3-D numerical simulations of an elliptical galaxy orbiting in a gas-rich cluster of galaxies indicate that gas dynamic stripping is less efficient than the results from previous, simpler calculations (Takeda et al. 1984; Gaetz et al. 1987) implied. This result is consistent with X-ray data for cluster elliptical galaxies. Hydrodynamic torques and di

Sultana N. Nahar, Manuel A. Bautista

We present the first detailed ab initio quantum mechanical calculations for total and state-specific recombination rate coefficients for e + Ni III --> Ni II. These rates are obtained using a unified treatment for total electron-ion recombination that treats the nonresonant radiative recombination and the resonant dielectronic recombination in a self-consist

Noam Soker, Saul Rappaport

Many planetary nebulae (PNe) exhibit distinctly non-axisymmetric structure in either (i) the shape of the nebula, or (ii) in the off-centered position of the illuminating star. By examining a large number of well resolved images of PNe we estimate that about 30-50 percents of all PNe exhibit distinctly non-axisymmetric structure. In this paper, we discuss ho

B. Vollmer, V. Cayatte, W. van Driel, P. A. Henning

ATCA 21 cm HI observations of the rich galaxy cluster ACO 3627 in the Great Attractor region are presented. Three fields of 30' diameter located within one Abell radius of ACO 3627 were observed with a resolution of 15'' and an rms noise of \sim 1 mJy/beam. Only two galaxies were detected in these fields. We compare their HI distribution to new o

T. G. Wang, M. Matsuoka, T. Kubo, T. Mihara

We report the detection of a very short time scale flare in the radio-loud narrow line quasars PKS 0558-504 by using ASCA. The X-ray count rates increased and decreased by a factor of two in 33 minutes, and possibly by 40% in as short as two minutes during this flare, confirming that such flare event does occur in this object with imaging detectors. The impl

J. Mikolajewska, R. J. Ivison, A. Omont

We discuss mm/submm spectra of a sample of symbiotic binary systems, and compare them with popular models proposed to account for their radio emission. We find that radio emission from quiescent S-type systems originates from a conical region of the red giant wind ionized by the hot companion (the STB model), whereas more complicated models involving winds f

Alvaro Dominguez

The Minkowski functionals are a mathematical tool to quantify morphological features of patterns. Some applications to the matter distribution in galaxy catalogues and N-body simulations are reviewed, with an emphasis on the effects of cosmic variance. The conclusions are that (i) the observed large-scale morphology is sensitive to cosmic variance on scales

E. Moy, B. Rocca-Volmerange, M. Fioc

We analyze the stellar and nebular energy distributions of starbursts using our evolutionary synthesis model PEGASE coupled to the photoionization code CLOUDY. The originality of this study is to relate the evolution and the metallicity of the starburst to the past star formation history of the host galaxy.We compare our model predictions to an observed samp

Naoki Seto

Evolution of power spectrum is studied for non-Gaussian models of structure formation. We generalize the dark-matter-approach to these models and find that the evolved spectrum at weakly nonlinear regime is mainly determined by a simple integral of the dark-matter-halo mass function in this approach. We also study the change of the nonlinear spectrum within

Z. Perjés

An infinite number of perturbed k=0 Friedmann cosmologies filled with dust and radiation is found. As we go up the sequence, the solutions contain an increasing number of integration functions. With the coordinate gauge adopted to co-move with the perturbed matter, the solution of a pair of coupled equations for the trace h of the metric perturbations and fo

Pavel Kroupa

The observed distribution of IMF shapes can be understood as statistical sampling from a universal IMF and variations that result from stellar-dynamical processes. However, young star clusters appear to have an IMF biased towards low-mass stars when compared to the Galactic disk IMF, which comprises an average populated by star-formation episodes occurring G

H. Kepa, J. Kutner-Pielaszek, J. Blinowski, A. Twardowski

Antiferromagnetic coupling between ferromagnetic layers has been observed for the first time in all-semiconductor superlattice structure EuS/PbS(001), by neutron scattering and magnetization measurements. Spin-dependent superlattice band structure effects are invoked to explain the possible origin and the strength of the observed coupling.

I. A. Bond, N. J. Rattenbury, J. Skuljan, F. Abe

A search for extra-solar planets was carried out in three gravitational microlensing events of high magnification, MACHO 98-BLG-35, MACHO 99-LMC-2, and OGLE 00-BUL-12. Photometry was derived from observational images by the MOA and OGLE groups using an image subtraction technique. For MACHO 98-BLG-35, additional photometry derived from the MPS and PLANET gro

Eric Braaten, Jungil Lee

We calculate the fragmentation function for a light quark to decay into a lepton pair to leading order in the QCD coupling constant. In the formal definition of the fragmentation function, a QED phase must be included in the eikonal factor to guarantee QED gauge invariance. We find that the longitudinal polarization fraction is a decreasing function of the f

I. A. Bond, F. Abe, R. J. Dodd, J. B. Hearnshaw

We describe observations carried out by the MOA group of the Galactic Bulge during 2000 that were designed to detect efficiently gravitational microlensing of faint stars in which the magnification is high and/or of short duration. These events are particularly useful for studies of extra-solar planets and faint stars. Approximately 17 degrees square were mo

Wim Vanroose

We discuss the interaction between two resonant states in a quantum double-well structure. The behaviour of the resonant states depends on the coupling between the wells, i.e. the height and width of the barrier that separates them. We distinguish a region with resonant tunneling and a region where the two resonances repel each other. The transition between

S. N. Dzyubak, Yu. I. Gubin, O. P. Dzyubak, P. V. Sorokin

As a result of nuclear power plant accidents, large areas receive radioactive inputs of Cs-137. This cesium accumulates in herbs growing in such territories. The problem is whether the herbs contaminated by radiocesium may be used as a raw material for medicine. The answer depends on the amount of Cs-137 transfered from the contaminated raw material to the m

A. M. Selvam

The spacing intervals of adjacent Riemann zeta zeros(non-trivial) exhibit fractal(irregular) fluctuations generic to dynamical systems in nature such as fluid flows, heart beat patterns, stock market price index, etc., and are associated with unpredictability or chaos. The power spectra of such fractal space-time fluctuations exhibit universal inverse power

Tibor Beke

If a Quillen model category can be specified using a certain logical syntax (intuitively, ``is algebraic/combinatorial enough''), so that it can be defined in any category of sheaves, then the satisfaction of Quillen's axioms over any site is a purely formal consequence of their being satisfied over the category of sets. Such data give rise to a

Emil J. Martinec, Gregory Moore

In the noncommutative field theory of open strings in a B-field, D-branes arise as solitons described as projection operators or partial isometries in a $C^*$ algebra. We discuss how D-branes on orbifolds fit naturally into this algebraic framework, through the examples of $R^n/G$, $T^n=R^n/Z^n$, and $T^n/G$. We also propose a framework for formulating D-bra

Carlo Ewerz

Hadronic final states at the LHC will be an interesting testing ground for QCD. A good understanding of QCD radiation will also be important for the discovery of new physics at the LHC. I discuss some aspects of this subject and give a few examples.

Qaisar Shafi, Zurab Tavartkiladze

We describe how bi-maximal neutrino mixing can be realized in realistic models based on MSSM and SUSY GUTs such as SU(5) and SO(10). A crucial role is played by an anomalous ${\cal U}(1)$ flavor symmetry, which also helps understand the observed charged fermion mass hierarchies and the magnitudes of the CKM matrix elements. While in MSSM a variety of solutio

D. Rainwater

Assuming that a Higgs sector is responsible for electroweak symmetry breaking, we attempt to address two important questions: How much better precision are various measurements of Higgs boson properties at a future linear collider than at the LHC? What can a future linear collider do for Higgs physics that the LHC cannot?

Nathan F. Lepora

This article presents a fairly complete description of the monopoles and dyons arising from an SU(5) gauge unification of the standard model. Topics discussed include: the spectrum of SU(5) monopoles; their gauge equivalence structure; their spherical symmetry; the construction of dyons; global charge; the intrinsic angular momenta of scalar boson-monopole c

T. Blum, N. Christ, C. Cristian, C. Dawson

We find the renormalisation coefficients of the quark field and the flavour non-singlet fermion bilinear operators for the domain wall fermion action, in the regularisation independent (RI) renormalisation scheme. Our results are from a quenched simulation, on a 16^3x32 lattice, with beta=6.0 and an extent in the fifth dimension of 16. We also discuss the ex

Miroslav Kopal

A search for the Standard Model Higgs boson is performed using the data collected by the four LEP experiments at center-of-mass energies between 202 GeV and 209 GeV. An average luminosity of 140 $pb^{-1}$ per experiment has been analyzed. A 2.6 $σ$ excess is observed in the LEP-wide combination for a Higgs boson mass hypothesis of around 114 GeV. All results

DONUT Collaboration

Using a prompt neutrino beam in which a nu_tau component was identified for the first time, the nu_tau magnetic moment was measured based on a search for an anomalous increase in the number of neutrino-electron interactions. One such event was observed when 2.3 were expected from background processes, giving an upper 90% confidence limit of 3.9x10^-7 Bohr ma

Lars Bildsten

I show that the recent calculation of Moffatt's regarding the viscous dissipation of a spinning coin overlooked the importance of the finite width of the viscous boundary layer. My new estimates are more in accord with that observed. I also point out that the frequency ``chirp'' of the specially designed toy ``Euler's Disk'' is simila

Gabriela Gonzalez

Angular fluctuations of suspended mirrors in gravitational wave interferometers are a source of noise both for the locking and the operation of the detectors. We describe here some of the sources of these fluctuations and methods for the estimation of their order of magnitude.

Jorge Pullin

News: - APS Prize on gravitation, by Cliff Will - TGG elections, by David Garfinkle - We hear that... by Jorge Pullin Research Briefs: - Experimental Unruh radiation?, by Matt Visser - Why is the universe accelerating?, by Beverly Berger - The Lazarus Project, by Richard Price - LIGO locks its first detector!, by Stan Whitcomb - Progress on the nonlinear r-m

Maurice H. P. M. van Putten

Long gamma-ray bursts (GRBs) are probably powered by high-angular momentum black hole-torus systems in suspended accretion. The torus will radiate gravitational waves as non-axisymmetric instabilities develop. The luminosity in gravitational-wave emissions is expected to compare favorably with the observed isotropic equivalent luminosity in GRB-afterglow emi

Todd M. Squires

It is shown that low Reynolds number fluid flows can cause suspended particles to respond as though they were in an equilibrium system with an effective potential. This general result follows naturally from the fact that different methods of moving particles in viscous fluids give rise to very different long-range flows. Two examples are discussed: electroph

A. R. Bhangale, P. Raychaudhuri, S. Sarkar, T. Banerjee

We report the observation of a peak in the microwave (9.55 GHz) surface resistance in an epitaxial DyBa2Cu3O7-y superconducting film in magnetic fields (parallel to the c axis) ranging between 0.2 to 0.9 Tesla. Such a peak is absent in the measurements done in zero-field. The temperature and field dependence of the peak suggests that this peak could be assoc

N. M. Chtchelkatchev

Conductance $G$ of a 2DEG-Superconductor (S) device in a high magnetic field is studied: $G(ν)$ is calculated. When the cyclotron diameter in 2DEG is larger than the width of the 2DEG-S surface then $G(ν)$ becomes nonmonotonous function due to the Aharonov--Bohm type interference of quasiparticles at the surface. At certain parameters of the junction the con

D. L. Jauncey, J. -P. Macquart

The intra-day variable source 0917+624 displays annual changes in its timescale of variability. This is explained in terms of a scintillation model in which changes in the variability timescale are due to changes in the relative velocity of the scintillation pattern as the Earth orbits the sun. (see also astro-ph/0102050)

M. Grenon, J. A. Mattei, L. Eyer, G. Foster

Accurate photometry was obtained for all programme stars during the 3.3-year HIPPARCOS mission. The final observing programme included several hundred Mirae (M), semiregular (SR) long-period and irregular (L) variables. A detailed calibration of the aging of the optics allowed the evaluation of very precise magnitudes over the whole range of star colours. Si

U. Munari, T. Tomov, B. F. Yudin, P. M. Marrese

A highly and rapidly variable bipolar mass outflow from StHa 190 has been discovered, the first time in a yellow symbiotic star. Permitted emission lines are flanked by symmetrical jet features and multi-component P-Cyg profiles, with velocities up to 300 km/sec. Given the high orbital inclination of the binary, if the jets leave the system nearly perpendicu

S. Stanimirović, A. Lazarian

This paper reports results on the statistical analysis of HI turbulence in the Small Magellanic Cloud (SMC). We use 21 cm channel maps, obtained with the Australia Telescope Compact Array and the Parkes telescope, and analyze the spectrum of observed intensity fluctuations as a function of the velocity slice thickness. We confirm predictions by Lazarian & Po

Y. Hoffman, A. Eldar, S. Zaroubi, A. Dekel

We present a method for decomposing the cosmological velocity field in a given volume into its divergent component due to the density fluctuations inside the volume, and its tidal component due to the matter distribution outside the volume. The input consists of the density and velocity fields that are reconstructed either by POTENT or by Wiener Filter from

B. W. Harris, J. F. Owens

The phase space slicing method of two cutoffs for next-to-leading-order Monte-Carlo style QCD corrections has been applied to many physics processes. The method is intuitive, simple to implement, and relies on a minimum of process dependent information. Although results for specific applications exist in the literature, there is not a full and detailed descr

Hungchong Kim

We study the higher order corrections of quark masses to the Gell-Mann$-$Oakes$-$Renner (GOR) relation by constructing QCD sum rules exclusively for pseudoscalar mesons from the axial-vector correlation function, $i \int d^4x~ e^{ip\cdot x} < 0| T[A_μ(x) A_ν(0)] | 0>$. To project out the pseudoscalar meson contributions, we apply $-p^μp^ν/p^2$ to this correl

Kentaro Nagamine, Masataka Fukugita, Renyue Cen, Jeremiah P. Ostriker

The luminosity function of galaxies is derived from a cosmological hydrodynamic simulation of a Lambda cold dark matter (CDM) universe with the aid of a stellar population synthesis model. At z=0, the resulting B band luminosity function has a flat faint end slope of α\approx -1.15 with the characteristic luminosity and the normalization in a fair agreement

V. V. Berejnov

In studies on Marangoni type motion of particles the surface tension is often approximated as a linear function of temperature. For deformable particles in a linear external temperature gradient far from the reference point this approximation yields a negative surface tension which is physically unrealistic. It is shown that H.Zhou and R.H.Davis J. Colloid I

M. C. M. Rentmeester, R. G. E. Timmermans, J. J. de Swart

The np differential cross section below 350 MeV neutron laboratory energy is studied using the energy-dependent Nijmegen partial-wave analysis PWA93. We analyze in detail three experiments, performed at LAMPF, at TRIUMF, and at the TSL facility in Uppsala. The issue of normalization of $np$ cross sections is discussed, where we distinguish between measured a

P. Bozek, P. Czerski

We investigate the relation between the binding energy and the Fermi energy and between different expressions for the pressure in cold nuclear matter. For a self-consistent calculation based on a $Φ$ derivable $T-$matrix approximation with off-shell propagators the thermodynamic relations are well satisfied unlike for a $G-$matrix or a $T-$matrix approach us

Ivan Kausz

We define a certain compactifiction of the general linear group and give a modular description for its points with values in arbitrary schemes. This is a first step in the construction of a higher rank generalization of Gieseker&#39;s degeneration of moduli spaces of vector bundles over a curve. We show that our compactification has similar properties as the

Arthur W. Apter, Joel David Hamkins

Can a supercompact cardinal kappa be Laver indestructible when there is a level-by-level agreement between strong compactness and supercompactness? In this article, we show that if there is a sufficiently large cardinal above kappa, then no, it cannot. Conversely, if one weakens the requirement either by demanding less indestructibility, such as requiring on

Camil Muscalu, Terence Tao, Christoph Thiele

We prove L^p estimates for the &#34;biest&#34;, a trilinear multiplier with singular symbol which arises naturally in the expansion of eigenfunctions of a Schrodinger operator, and which is also related to the bilinear Hilbert transform. In a previous paper these estimates were obtained for a simpler Walsh model for this operator, but in the Fourier case add

Camil Muscalu, Terence Tao, Christoph Thiele

We prove L^p estimates for the Walsh model of the &#34;biest&#34;, a trilinear multiplier with singular symbol which arises naturally in the expansion of eigenfunctions of a Schrodinger operator, and which is also related to the bilinear Hilbert transform. The corresponding estimates for the Fourier model will be obtained in the sequel of this paper.

J. P. B. C. de Melo, A. E. A. Amorim, Lauro Tomio, T. Frederico

The lower bound masses of the ground-state relativistic three-boson system in 1+1, 2+1 and 3+1 space-time dimensions are obtained. We have considered a reduction of the ladder Bethe-Salpeter equation to the light-front in a model with renormalized two-body contact interaction. The lower bounds are deduced with the constraint of reality of the two-boson subsy

Chung-I Tan

The Maldacena conjecture that QCD is holographically dual to gravity in extra dimensions is briefly reviewed. On the basis of this duality conjecture, the complete glueball spectrum is computed which bares a striking resemblance to the known $QCD_4$ spectrum as determined by lattice simulations. In particular, a strong coupling expansion for the Pomeron inte

B. W. Harris, E. Laenen, L. Phaf, Z. Sullivan

A new next-to-leading order Monte Carlo program for calculation of fully differential single top quark final states is described and first results presented. Both the s- and t-channel contributions are included.

A. D. Dolgov

Lepton asymmetry generated in the early universe by neutrino oscillations into sterile partners is calculated. Kinetic equations are analytically reduced to a simple form that permits an easy numerical treatment. Asymptotic values of the asymmetry are at the level of 0.2-0.3 and are reasonably close to those obtained by other groups, though the approach to a

L3 Collaboration

The reaction e+e- -> e+e- gamma* gamma* -> e+e- hadrons for quasi-real photons is studied using data from root(s) = 183 GeV up to 202 GeV. Results on the total cross sections sigma(e+e- -> e+e- hadrons) and sigma(+e- gamma* gamma* -> e+e- hadrons) are given for the two-photon centre-of-mass energies 5 GeV < Wgammagamma < 185 GeV. The total cross section of t

L3 Collaboration

The process e^+e^- -> Z gamma gamma -> q q~ gamma gamma is studied in 0.5 fb-1 of data collected with the L3 detector at centre-of-mass energies between 130.1 GeV and 201.7 GeV. Cross sections are measured and found to be consistent with the Standard Model expectations. The study of the least energetic photon constrains the quartic gauge boson couplings to -

L3 Collaboration

Using data collected with the L3 detector near the Z resonance, corresponding to an integrated luminosity of 150pb-1, the branching fractions of the tau lepton into electron and muon are measured to be B(tau->e nu nu) = (17.806 +- 0.104 (stat.) +- 0.076 (syst.)) %, B(tau->mu nu nu) = (17.342 +- 0.110 (stat.) +- 0.067 (syst.)) %. From these results the ratio

Ming-Yang Kao, Jared Samet, Wing-Kin Sung

The double digest problem is a common NP-hard approach to constructing physical maps of DNA sequences. This paper presents a new approach called the enhanced double digest problem. Although this new problem is also NP-hard, it can be solved in linear time in certain theoretically interesting cases.

Tsan-sheng Hsu, Ming-Yang Kao

A graph is componentwise biconnected if every connected component either is an isolated vertex or is biconnected. We present a linear-time algorithm for the problem of adding the smallest number of edges to make a bipartite graph componentwise biconnected while preserving its bipartiteness. This algorithm has immediate applications for protecting sensitive i

Yuyu Chen, Ming-Yang Kao, Hsueh-I Lu

In a multiple-object auction, every bidder tries to win as many objects as possible with a bidding algorithm. This paper studies position-randomized auctions, which form a special class of multiple-object auctions where a bidding algorithm consists of an initial bid sequence and an algorithm for randomly permuting the sequence. We are especially concerned wi

Zhi-Zhong Chen, Xin He, Ming-Yang Kao

Given a planar graph G and a sequence C_1,...,C_q, where each C_i is a family of vertex subsets of G, we wish to find a plane embedding of G, if any exists, such that for each i in {1,...,q}, there is a face F_i in the embedding whose boundary contains at least one vertex from each set in C_i. This problem has applications to the recovery of topological info

Jesus Salas, Robert Shrock

We present exact solutions for the zero-temperature partition function of the $q$-state Potts antiferromagnet (equivalently, the chromatic polynomial $P$) on tube sections of the simple cubic lattice of fixed transverse size $L_x \times L_y$ and arbitrarily great length $L_z$, for sizes $L_x \times L_y = 2 \times 3$ and $2 \times 4$ and boundary conditions (

A. S. Alexandrov

In view of some recent works on the role of vertex corrections in the electron-phonon system we readress an important question of the validity of the Migdal-Eliashberg theory. Based on the solution of the Holstein model and inverse coupling constant expansion, we argue that the standard Feynman-Dyson perturbation theory by Migdal and Eliashberg with or witho

Johann Kroha

In recent experiments the non-equilibrium distribution function $f(E,U)$ in diffusive Cu and Au quantum wires at a transport voltage $U$ shows scaling behavior, $f(E,U)=f(E/eU)$, indicating a non-Fermi liquid interaction with {\it non-vanishing} T=0 scattering rate. The two-channel Kondo (2CK) effect, possibly produced by degenerate two-level systems, is kno

A. Minguzzi, N. H. March, M. P. Tosi

Two equations are constructed which reflect, for fermions moving independently in a spherical harmonic potential, a differential virial theorem and a relation between the turning points of kinetic energy and particle densities. These equations are used to derive a differential equation for the particle density and a non-local kinetic energy functional.

A. Minguzzi, N. H. March, M. P. Tosi

We evaluate analytically some ground state properties of two-dimensional harmonically confined Fermi vapors with isotropy and for an arbitrary number of closed shells. We first derive a differential form of the virial theorem and an expression for the kinetic energy density in terms of the fermion particle density and its low-order derivatives. These results

Johann Kroha

In diffusive Cu and Au quantum wires at finite transport voltage $U$ the non-equilibrium distribution function $f(E,U)$ exhibits scaling behavior, $f(E,U)=f(E/eU)$, indicating anomalous energy relaxation processes in these wires. We show that in nonequilibrium the Kondo effect, generated either by magnetic impurities (single-channel Kondo effect) or possibly

D. Y. Sun, X. G. Gong

In this letter, by writing the volume as a function of coordinates of atoms, we present a new constant-pressure molecular dynamics method with parameters free. This method is specially appropriate for the finite system in which the periodic boundary condition does not exist. Simulations on the carbon nanotube and the Ni nanoparticle clearly demonstrate the v

H. Diamant, T. A. Witten, C. Ege, A. Gopal

We theoretically study the topography of a biphasic surfactant monolayer in the vicinity of domain boundaries. The differing elastic properties of the two phases generally lead to a nonflat topography of ``mesas&#39;&#39;, where domains of one phase are elevated with respect to the other phase. The mesas are steep but low, having heights of up to 10 nm. As t

H. F. Chau, H. Xu, L. -G. Liu

Tolls are collected on many highways as a means of traffic control and revenue generation. However, the presence of tollbooths on highway surely slows down traffic flow. Here, we investigate how the presence of tollbooths affect the average car speed using a simple-minded single lane deterministic discrete traffic model. More importantly, the model is exactl

Gerry Gilmore

The stellar initial mass function (IMF) is an underlying distribution function which determines many important observables, from the number of ionizing photons in a population of some age and metallicity, through the creation rate of various chemical elements, to the mass to light ratio of a system. This significance, together with the empirical difficulty t

J. L. Hou, S. Boissier, N. Prantzos

In this paper we point out a previously unnoticed anticorrelation between the observed abundance ratio [X/Zn] (where Zn is assumed to be undepleted and X stands for the refractories Fe, Cr and Ni) and metal column density ([Zn/H]+log(N{HI})) in DLAs. We suggest that this trend is an unambiguous sign of dust depletion, since metal column density is a measure

Heino Falcke, Sera Markoff

The preliminary detection of the Galactic Center black hole Sgr A* in X-rays by the Chandra mission, as well as recent mm-VLBI measurements, impose strict constraints on this source. Using a relativistic jet model for Sgr A*, we calculate the synchrotron and synchrotron self-Compton emission. The predicted spectrum provides an excellent fit to the radio spec

Y. Maeda, F. K. Baganoff, E. D. Feigelson, M. Morris

We report on the X-ray emission from the shell-like, non-thermal radio source Sgr A East located in the inner few parsecs of the Galaxy based on observations made with the ACIS detector on board Chandra. This is the first time Sgr A East has been clearly resolved from other complex structures in the region. The X-ray emitting region is concentrated within th

R. D. Rohrmann

We present a detailed calculation of model atmospheres for DA white dwarfs. Our atmosphere code solves the atmosphere structure in local thermodynamic equilibrium with a standard partial linearization technique, which takes into account the energy transfer by radiation and convection. This code incorporates recent improved and extended data base of collision

Richard H. Cyburt, Brian D. Fields, Keith A. Olive

The theoretical predictions of big bang nucleosynthesis (BBN) are dominated by uncertainties in the input nuclear reaction cross sections. In this paper, we examine the impact on BBN of the recent compilation of nuclear data and thermonuclear reactions rates by the NACRE collaboration. We confirm that the adopted rates do not make large overall changes in ce

M Boiti, F Pempinelli, B Prinari, A Spire

The inverse scattering theory for the sine-Gordon equation discretized in space and both in space and time is considered.

J. X. Lu

The dynamics of a Dp brane can be described either by an open string ending on this brane or by an open D(p - 2) brane ending on the same Dp brane. The ends of the open string couple to a Dp brane worldvolume gauge field while the boundary of the open D(p - 2) brane couples to a (p - 2)-form worldvolume potential whose field strength is Poincare dual to that

Andrzej Czarnecki, William J. Marciano

QED, Hadronic, and Electroweak Standard Model contributions to the muon anomalous magnetic moment, a_mu = (g_mu-2)/2, and their theoretical uncertainties are scrutinized. The status and implications of the recently reported 2.6 sigma experiment vs.theory deviation a_mu^{exp}-a_mu^{SM} = 426(165) times 10^{-11} are discussed. Possible explanations due to supe

C. A. Terrero-Escalante, D. J. Schwarz, A. A. Garcia

We present a new approximation scheme that allows us to increase the accuracy of analytical predictions of the power spectra of inflationary perturbations for two specific classes of inflationary models. Among these models are chaotic inflation with a monomial potential, power-law inflation and natural inflation (inflation at a maximum). After reviewing the

Elena N. Govorun, Victor A. Ivanov, Alexei R. Khokhlov, Pavel G. Khalatur

We consider the statistical properties of primary sequences of two-letter HP copolymers (H for hydrophobic and P for polar) designed to have water soluble globular conformations with H monomers shielded from water inside the shell of P monomers. We show, both by computer simulations and by exact analytical calculation, that for large globules and flexible po

B. E. White

We give a complete treatment of factorisation of Deeply Virtual Compton Scattering (DVCS) in the generalised Bjorken limit, using the local Operator Product Expansion (OPE). The method allows a straightforward proof that, at leading twist, the DVCS amplitude factorises into an integral over coefficient functions and Skewed Parton Distribution Functions (SPDF

J. Alvarez-Muñiz, E. Zas

We explore the feasibility of using the Moon as a detector of extremely high energy (>10^19 eV) cosmic rays and neutrinos. The idea is to use the existing radiotelescopes on Earth to look for short pulses of Cherenkov radiation in the GHz range emitted by showers induced just below the surface of the Moon when cosmic rays or neutrinos strike it. We estimate

C. A. Clarkson, A. A. Coley

Observations of the high degree of isotropy of the cosmic microwave background are commonly believed to indicate that the Universe is `almost&#39; Friedmann-Lemaitre-Robertson-Walker (at least since the time of last scattering). Theoretical support for this belief comes from the so-called Ehlers-Geren-Sachs Theorem. We show that a generalization of this theo

Colin D. Wilson, Chris Done

We study the spectral properties of the first 14 observations of the rise to outburst phase of the X-ray transient J1550-564. Using the PCA and HEXTE instruments, we find that the 3-200 keV spectra smoothly pass from a standard low/hard state to a very high state. The classic high state is never encountered possibly indicating that it is not a phenomenon of

O. Jahn, V. V. Sreedhar

The maximal invariance group of Newton&#39;s equations for a free nonrelativistic point particle is shown to be larger than the Galilei group. It is a semi-direct product of the static (nine-parameter) Galilei group and an $SL(2,R)$ group containing time-translations, dilations and a one-parameter group of time-dependent scalings called {\it expansions}. Thi

S. Moretti

We compute the contribution to charged Higgs boson pair production at the Large Hadron Collider (LHC) due to the scattering of two electroweak (EW) gauge bosons, these being in turn generated via bremsstrahlung off incoming quarks: q q --> q q V^*V^* --> q q H^+H^- (V=gamma,Z,W^{+/-}). We verify that the production cross section of this mode is tan beta inde

I. L. Grach, P. Yu. Kulikov, I. M. Narodetskii

A generalization of the parton-like formula is used for the first time to find the differential distributions in the inclusive semileptonic weak decays of the B meson. The main features of this new approach are the treatment of the b-quark as an on-mass-shell particle and the inclusion of the effects arising from the b-quark transverse motion in the B-meson.

D. Behnke, D. Blaschke, V. N. Pervushin, D. Proskurin

We consider cosmological consequences of a conformal invariant formulation of Einstein&#39;s General Relativity where instead of the scale factor of the spatial metrics in the action functional a massless scalar (dilaton) field occurs which scales all masses including the Planck mass. Instead of the expansion of the universe we get the Hoyle-Narlikar type of

M. Enjalran, F. Hebert, G. G. Batrouni, R. T. Scalettar

We study the effects of disorder on long-range antiferromagnetic correlations in the half-filled, two dimensional, repulsive Hubbard model at T=0. A mean field approach is first employed to gain a qualitative picture of the physics and to guide our choice for a trial wave function in a constrained path quantum Monte Carlo (CPQMC) method that allows for a mor

Fiona Hoyle, P. J. Outram, T. Shanks, S. M. Croom

(ABRIDGED) We present a power spectrum analysis of the 10K catalogue from the 2dF QSO Redshift Survey. We compare the redshift-space power spectra of QSOs to those measured for galaxies and Abell clusters at low redshift and find that they show similar shapes in their overlap range, 50-150h^{-1}Mpc, with P_QSO(k)\propto k^{-1.4}. The amplitude of the QSO pow

Otto C. W. Kong

The generic supersymmetric standard model is a model built from a supersymmetrized standard model field spectrum the gauge symmetries only. The popular minimal supersymmetric standard model differs from the generic version in having R-parity imposed by hand. We review an efficient formulation of the model in which all the admissible R-parity violating terms

F. Ceccherini, D. Bauer

We study numerically the interaction between an intense circularly polarized laser field and an electron moving in a potential which has a discrete cylindrical symmetry with respect to the laser pulse propagation direction. This setup serves as a simple model, e.g., for benzene and other aromatic compounds. From general symmetry considerations, within a Floq

Takahiro Miura, Eiichi Takasugi, Yoshitaka Kuno, Masaki Yoshimura

We analyzed T-violation in neutrino oscillation by using perturbation methods with respect to $Δm_{21}^2L/2E$ and $δa(x)L/2E$, where $δa(x)$ represents the matter density fluctuation from its average value. We found that the matter contribution to T-violation arises from interferences between $Δm_{21}^2L/2E$ and $δa(x) L/2E$. In the 2nd order, the symmetric

A. Lipowski, M. Droz

We study a recently introduced ladder model which undergoes a transition between an active and an infinitely degenerate absorbing phase. In some cases the critical behaviour of the model is the same as that of the branching annihilating random walk with $N\geq 2$ species both with and without hard-core interaction. We show that certain static characteristics

Gautam I. Menon

A universal phase diagram for type-II superconductors with weak point pinning disorder is proposed. In this phase diagram, two thermodynamic phase transitions generically separate a ``Bragg glass&#39;&#39; from the disordered liquid. Translational correlations in the intervening ``multi-domain glass&#39;&#39; phase are argued to exhibit a significant degree

Alex Degtyarev, Viatcheslav Kharlamov

We show that a real rational (over $\C$) surfaces are quasi-simple, i.e., that such a surface is determined up to deformation in the class of real surfaces by the topological type of its real structure.