January 2002 arXiv papers — page 13

Enrico De Micheli, Giovanni Alberto Viano

Sequences of rotational resonances (rotational bands) and corresponding antiresonances are observed in ion collisions. In this paper we propose a description which combines collective and single-particle features of cluster collisions. It is shown how rotational bands emerge in many-body dynamics, when the degeneracies proper of the harmonic oscillator spect

B. K. Patra, Jan-e Alam, Pradip Roy, Sourav Sarkar

The space-time evolution of the hot and dense matter formed after the collisions of heavy nuclei at ultra-relativistic energies is investigated using (3+1) dimensional hydrodynamical models. The effects of the spectral shift of the hadronic properties are incorporated in the equation of state (EOS) of the evolving matter. In-medium shift of hadronic properti

F. Gulminelli, Ph. Chomaz, M. Bruno, M. D'Agostino

A good quality scaling of the cluster size distributions is obtained for the Lattice Gas Model using the Fisher's ansatz for the scaling function. This scaling identifies a pseudo-critical line in the phase diagram of the model that spans the whole (subcritical to supercritical) density range. The independent cluster hypothesis of the Fisher approach is

Yun Zhang et. al

It is shown that the quark mass density-dependent model can not be used to explain the process of the quark deconfinement phase transition because the quark confinement is permanent in this model. A quark mass density- and temperature-dependent model in which the quark confinement is impermanent has been suggested. We argue that the vacuum energy density B i

M. Drew LaMar, Yingyong Qi, Jack Xin

Vocal fold (VF) motion is a fundamental process in voice production, and is also a challenging problem for direct numerical computation because the VF dynamics depend on nonlinear coupling of air flow with the response of elastic channels (VF), which undergo opening and closing, and induce internal flow separation. A traditional modeling approach makes use o

A. Ludu, R. F. O'Connell, J. P. Draayer

We use a multi-scale similarity analysis which gives specific relations between the velocity, amplitude and width of localized solutions of nonlinear differential equations, whose exact solutions are generally difficult to obtain.

Christophe Sabot

Starting from a finitely ramified self-similar set $X$ we can construct an unbounded set $X_{<\infty>}$ by blowing-up the initial set $X$. We consider random blow-ups and prove elementary properties of the spectrum of the natural Laplace operator on $X_{<\infty>}$ (and on the associated lattice). We prove that the spectral type of the operator is almost sure

M. de Leon, D. Martin de Diego

This paper presents a method to construct variational integrators for time-dependent lagrangian systems. The resulting algorithms are symplectic, preserve the momentum map associated with a Lie group of symmetries and also describe the energy variation.

E. Binz, M. de Leon, D. Martin de Diego, D. Socolescu

A multisymplectic setting for classical field theories subjected to non-holonomic constraints is presented. The infinite dimensional setting in the space of Cauchy data is also given.

Justin Roberts

Everyone knows that the Euler characteristic of a combinatorial manifold is given by the alternating sum of its numbers of simplices. It is shown that there are other linear combinations of the numbers of simplices which are combinatorial invariants, but that all such invariants are multiples of the Euler characteristic.

Thomas J. Haines, Alexandra Pettet

We give explicit formulae for certain elements occurring in the Bernstein presentation of an affine Hecke algebra, in terms of the usual Iwahori- Matsumoto generators. We utilize certain minimal expressions for said elements and we give a sheaf-theoretic interpretation for the existence of these minimal expressions.

S. Dimiev

This note is a continuation of the paper [2] (see references). We describe some natural pseudogroup structures on almost complex manifolds of type $m$. A kind of coherency is discussed for the sheaf of almost holomorphic functions.

Martin Engman

In the special case of S^1 invariant metrics on S^2, we find necessary and sufficient conditions for the existence of isometric embeddings into the canonical R^3, in other words: a Weyl type theorem with converse.

J. J. Duistermaat

The minimal surface equation $Q$ in the second order contact bundle of $R^3$, modulo translations, is provided with a complex structure and a canonical vector-valued holomorphic differential form $Omega$ on $Q\0$. The minimal surfaces $M$ in $R^3$ correspond to the complex analytic curves $C$ in $Q$, where the derivative of the Gauss map sends $M$ to $C$, an

Ralf Schindler

Steel and Welch have shown that K is Σ^1_3 correct if the reals are closed under sharps but 0^\pistol doesn&#39;t exist. We&#39;ll give a simple and purely combinatorial proof of the following: K is Σ^1_3 correct if the reals are closed under sharps, there is no inner model with a Woodin cardinal, K exists, and * holds. Here, * is an assertion which can easi

Giuseppe Dito, Daniel Sternheimer

We start with a short exposition of developments in physics and mathematics that preceded, formed the basis for, or accompanied, the birth of deformation quantization in the seventies. We indicate how the latter is at least a viable alternative, autonomous and conceptually more satisfactory, to conventional quantum mechanics and mention related questions, in

D. S. Grebenkov

Generalizing the well-known relations on characteristic functions on a plane to the case of a one-dimensional regular surface (curve) with compact support, we establish implicit equations for these functions. Introducing an approximation, we solve the combinatorial problems and reduce these equations to a set of linear equations for a finite number of unknow

David Bessis

We construct a new monoid structure for Artin groups associated with finite Coxeter systems. This monoid shares with the classical positive braid monoid a crucial algebraic property: it is a Garside monoid. The analogy with the classical construction indicates there is a ``dual&#39;&#39; way of studying Coxeter systems, where the pair (W,S) is replaced by (W

R. M. Cavalcanti

We compute the Casimir energy of a real scalar field in the presence of a pair of partially transparent plane mirrors, modeled by Dirac delta potentials.

Noah Graham, Robert L. Jaffe, Herbert Weigel

We review the framework we and our collaborators have developed for the study of one-loop quantum corrections to extended field configurations in renormalizable quantum field theories. We work in the continuum, transforming the standard Casimir sum over modes into a sum over bound states and an integral over scattering states weighted by the density of state

L. M. Abreu, A. E. Santana, A. Ribeiro Filho

The notion of Poincare gauge manifold ($G$), proposed in the context of an (1+1) gravitational theory by Cangemi and Jackiw (D. Cangemi and R. Jackiw, Ann. Phys. (N.Y.) 225 (1993) 229), is explored from a geometrical point of view. First $G$ is defined for arbitrary dimensions, and in the sequence a symplectic structure is attached to $T*G$. Treating the cas

D. M. Gitman, I. V. Tyutin

We consider a class of Lagrangian theories where part of the coordinates does not have any time derivatives in the Lagrange function (we call such coordinates degenerate). We advocate that it is reasonable to reconsider the conventional definition of singularity based on the usual Hessian and, moreover, to simplify the conventional Hamiltonization procedure.

Hiroki Emoto, Yutaka Hosotani, Takahiro Kubota

In the SU(2)_{L} x U(1)_{Y} standard electroweak theory coupled with the Einstein gravity, new topological configurations naturally emerge, if the spatial section of the universe is globally a three-sphere(S^3) with a small radius. The SU(2)_L gauge fields and Higgs fields wrap the space nontrivially, residing at or near a local minimum of the potential. As

Daniel S. Akerib, Sean M. Carroll, Marc Kamionkowski, Steven Ritz

The past few years have seen dramatic breakthroughs and spectacular and puzzling discoveries in astrophysics and cosmology. In many cases, the new observations can only be explained with the introduction of new fundamental physics. Here we summarize some of these recent advances. We then describe several problem in astrophysics and cosmology, ripe for major

M. Battaglia, J. Barron, M. Dima, L. Hamilton

Scenarios are developed for runs at a Linear Collider, in the case that there is a rich program of new physics.

Yu. A. Simonov

An effective Lagrangian for the light quark in the field of a static source is derived systematically using the exact field correlator expansion. The lowest Gaussian term is bosonized using nonlocal colorless bosonic fields and a general structure of effective chiral Lagrangian is obtained containing all set of fields. The new and crucial result is that the

Shi-yuan Li, Feng-lan Shao, Qu-bing Xie, Qun Wang

Hadronic events in $e^+ e^- \to Z^0$ are generated by a Monte-Carlo model including the production of colour separate states. These events are compared with those produced by the JETSET with default set of parameters where the colour connections are colour singlet chains. By selecting two-jet-like events and a sensitive observable, we find that these two kin

J. I. Kapusta, S. M. H. Wong

No conventional picture of nucleus-nucleus collisions has yet been able to explain the abundance of Omega and AntiOmega in central collisions between Pb nuclei at 158 A GeV at the CERN SPS. We argue that such a deviation from predictions of statistical thermal models and numerical simulations is evidence that they are produced as topological defects in the f

T. Alexopoulos, E. W. Anderson, A. T. Bujak, D. D. Carmony

We have measured deconfined hadronic volumes, $4.4 < V < 13.0$ fm$^{3}$, produced by a one dimensional (1D) expansion. These volumes are directly proportional to the charged particle pseudorapidity densities $6.75 < dN_{c}/dη< 20.2$. The hadronization temperature is $T = 179.5 \pm 5$ (syst) MeV. Using Bjorken&#39;s 1D model,the hadronization energy density i

Marcelo Salgado

Using the 3+1 formalism of general relativity we obtain the equations governing the dynamics of spherically symmetric spacetimes with arbitrary sources. We then specialize for the case of perfect fluids accompanied by a flow of interacting massless or massive particles (e.g. neutrinos) which are described in terms of relativistic transport theory. We focus i

S. Dain, C. O. Lousto, R. Takahashi

We obtain an explicit solution of the momentum constraint for conformally flat, maximal slicing, initial data which gives an alternative to the purely longitudinal extrinsic curvature of Bowen and York. The new solution is related, in a precise form, with the extrinsic curvature of a Kerr slice. We study these new initial data representing spinning black hol

Piotr T. Chrusciel, Gabriel Nagy

We give a Hamiltonian definition of mass for spacelike hypersurfaces in space-times with metrics which are asymptotic to the anti-de Sitter one, or to a class of generalizations thereof. We show that our definition provides a geometric invariant for a spacelike hypersurface embedded in a space-time.

Joseph Y. Halpern

I consider issues in distributed computation that should be of relevance to game theory. In particular, I focus on (a) representing knowledge and uncertainty, (b) dealing with failures, and (c) specification of mechanisms.

Emanuel Derman

What return should you expect when you take on a given amount of risk? How should that return depend upon other people&#39;s behavior? What principles can you use to answer these questions? In this paper, we approach these topics by exploring the consequences of two simple hypotheses about risk. The first is a common-sense invariance principle: assets with t

J. K. Freericks, B. K. Nikolic, P. Miller

We review the application of dynamical mean-field theory to Josephson junctions and study how to maximize the characteristic voltage IcRn which determines the width of a rapid single flux quantum pulse, and thereby the operating speed in digital electronics. We study a wide class of junctions ranging from SNS, SCmS (where Cm stands for correlated metal), SIN

Pallab Goswami, Subinoy Das, J. K. Bhattacharjee

We consider photoemission from a two-electron quantum dot and find analytic expression for the cross-section. We show that the emission cross-section from the ground state as a function of magnetic field has sharp discontinuities corresponding to the singlet-triplet transitions for low magnetic fields and the transitions between magic numbers (2J+1) for high

N. V. Brilliantov, J. M. Rubi

A simple analytical microscopic expression for the surface tension of liquids $γ$ is obtained which is in a good agreement with available data of numerical experiments. We apply the integral transformation that maps the fluid Hamiltonian onto the field-theoretical Hamiltonian and show that the order parameter of the effective Hamiltonian corresponds to the o

V. K. Dugaev, J. Barnas, A. Lusakowski, L. A. Turski

We present theoretical description of conduction electrons interacting with a domain wall in ferromagnetic metals. The description takes into account interaction between electrons. Within the semiclassical approximation we calculate the spin and charge distributions, particularly their modification by the domain wall. In the same approximation we calculate l

N. M. Bogoliubov, J. Timonen, M. B. Zvonarev

The dynamics of two traps with ultracold atoms and connected by Josephson type coupling, is shown to exhibit a transition from dispersive dynamics to localized coherent oscillations. This transition is controlled by coupling strength and energy offset between the traps. The dynamics is also shown to be exactly that of a Heisenberg chain with a linear magneti

K. K. Muller-Nedebock, H. L. Frisch, J. K. Percus

We make use of the previously developed formalism for a monomer ensemble and include angular dependence of the segments of the polymer chains thus described. In particular we show how to deal with stiffness when the polymer chain is confined to certain regions. We investigate the stiffness from the perspectives of a differential equation, integral equations,

Boris M. Shipilevsky

We study dynamics of filling of an initially empty finite medium by diffusing particles $A$ and $B$, which arise on the surface upon dissociation of $AB$ molecules, impinging on it with a fixed flux density $I$, and desorb from it by the reaction $A + B\to AB\to 0$. We show that once the bulk diffusivities differ ($p=D_{A}/D_{B}<1$), there exists a critical

Indranil Rudra, S. Ramasesha, Diptiman Sen

Using an efficient numerical scheme that exploits spatial symmetries and spin-parity, we have obtained the exact low-lying eigenstates of exchange Hamiltonians for ferric wheels up to Fe$_{12}$. The largest calculation involves the Fe$_{12}$ ring which spans a Hilbert space dimension of about 145 million for M$_s$=0 subspace. Our calculated gaps from the sin

Satoshi Fujimoto

We investigate the Hubbard chains network model defined on corner-sharing tetrahedra (the pyrochlore lattice) which is a possible microscopic model for the heavy fermion state of LiV_2O_4. Based upon this model, we can explain transport, magnetic, and thermodynamic properties of LiV_2O_4. We calculate the spin susceptibility, and the specific heat coefficien

J. H. Shim, S. K. Kwon, B. I. Min

We have investigated electronic structures of antiperovskite GaCMn$_3$ and related Mn compounds SnCMn$_3$, ZnCMn$_3$, and ZnNMn$_3$. In the paramagnetic state of GaCMn$_3$, the Fermi surface nesting feature along the $Γ{\rm R}$ direction is observed, which induces the antiferromagnetic (AFM) spin ordering with the nesting vector {\bf Q} $\sim Γ{\rm R}$. Calc

B. Roessli, P. Boeni, W. E. Fischer, Y. Endoh

Polarized neutrons are used to determine the antisymmetric part of the magnetic susceptibility in non-centrosymmetric MnSi. The paramagnetic fluctuations are found to be incommensurate with the chemical lattice and to have a chiral character. We argue that antisymmetric interactions must be taken into account to properly describe the critical dynamics in MnS

J. Fernández-Rossier, L. J. Sham

In a study of the ferromagnetic phase of a multilayer digital ferromagnetic semiconductor in the mean-field and effective-mass approximations, we find the exchange interaction to have the dominant energy scale of the problem, effectively controlling the spatial distribution of the carrier spins in the digital ferromagnetic heterostructures. In the ferromagne

R. Riera, J. L. Marin, R. Betancourt-Riera

A general theory of superconductivity based on the pairing of electrons that belong to different electronic bands is presented. These electronic bands arise because of a symmetry breaking at the critical temperature in such a way that one electron sees the other as if its mass would be negative. This symmetry breaking leads also to an energy gap (centered ro

L. Wang, H. S. Lim, C. K. Ong

In this paper, we employ a continuous Ginzburg-Landau model to study the behaviors of the parallel upper critical field of an intrinsically-layered superconductor. Near $T_c$ where the order parameter is nearly homogeneous, the parallel upper critical field is found to vary as $(1-T/T_c)^{1/2}$. With a well-localized order parameter, the same field temperatu

L. Wang, H. S. Lim, C. K. Ong

Within a continuous Ginzburg-Landau model for layered superconductors, two procedures are proposed to determine the upper critical field parallel to the $c$-$a$ crystal plane with an angle $θ$ tilted from the c-axis. For an intrinsically layered superconductor, the upper critical fields for $θ\to 90^\circ$, as determined by the two procedures, are consistent

Makoto Itoh

A Comment on the Letter by P. Kratzer and M. Scheffler, Phys. Rev. Lett. 88, 036102 (2002).

M. E. Zhitomirsky

The thermal order by disorder effect in magnetic field is studied for a classical Heisenberg antiferromagnet on the kagome lattice. Using analytical arguments we predict a unique H-T phase diagram for this strongly frustrated magnet: states with a coplanar and a uniaxial triatic order parameters respectively at low and high magnetic fields and an incompressi

Peter Markos

We study numerically the form of the conductance distribution in the non-metallic regime for (1) weakly disordered systems which become insulating due to increase of the system length and (2) cubic d-dimensional systems, in which localization occours due to the increase of the disorder strength. In the three dimensional systems, we prove that the one-channel

Andrei M. Beloborodov

Observations and models of GRBs are reviewed with an emphasis on the early phase of the burst. Recent revision of the early afterglow model is described.

A. Del Popolo, K. Y. Eksi

In this paper, we further develop the model for the migration of planets introduced in Del Popolo et al. (2001). We first model the protoplanetary nebula as a time-dependent accretion disc and find self-similar solutions to the equations of the accretion disc that give to us explicit formulas for the spatial structure and the temporal evolution of the nebula

Gregory J. Herczeg, Jeffrey L. Linsky, Jeff A. Valenti, Chris M. Johns-Krull

We observed the classical T Tauri star TW Hya with \textit{HST}/STIS using the E140M grating, from 1150--1700 Å, with the E230M grating, from 2200--2900 Å, and with \FUSE from 900--1180 Å. Emission in 143 Lyman-band H$_2$ lines representing 19 progressions dominates the spectral region from 1250--1650 Å. The total H$_2$ emission line flux is $1.94 \times 10^

Philip J. Armitage, Priyamvada Natarajan

We study the evolution of disk accretion during the merger of supermassive black hole binaries in galactic nuclei. In hierarchical galaxy formation models, the most common binaries are likely to arise from minor galactic mergers, and have unequal mass black holes. Once such a binary becomes embedded in an accretion disk at a separation of the order of 0.1 pc

A. C. A. Boogert, M. R. Hogerheijde, C. Ceccarelli, A. G. G. M. Tielens

A (sub-)millimeter line and continuum study of the class I protostar Elias 29 in the Rho Ophiuchi molecular cloud is presented, whose goals are to understand the nature of this source, and to locate the ices that are abundantly present along this line of sight. Within 15-60&#34; beams, several different components contribute to the line emission. Two differe

L. Verozub

The hypothesis that radiation of Sgr A* is caused by accretion onto a supermassive compact object without the events horizon is studied. The main equations of the accretion and a relativistic equation of the trasfer radiation are obtained. The synchrotron spectrum in the vicinity of the maximum is considered.

Clive N. Tadhunter

In this article I review the dominant physical mechanisms in the extended emission line regions (EELR) of powerful radio galaxies at low redshifts and, in particular, the balance between jet-induced shocks and AGN photoionization. I consider the evidence for jet-induced shocks based on morphological, kinematical and ionization (diagnostic diagram) informatio

K. M. Belotsky, T. Damour, M. Yu. Khlopov

It has been recently pointed out that any primary galactic population of Weakly Interacting Massive Particles (WIMP) generates, through collisions with solar matter, a secondary population of ``slow&#39;&#39; WIMPs trapped in the inner solar system. We show that taking into account this ``slow&#39;&#39; solar-system population dramatically enhances the possi

Steven Furlanetto, Abraham Loeb

Clusters of galaxies are enriched with positrons from jets of active galactic nuclei (AGNs) or from the interaction of cosmic rays with the intracluster gas. We follow the cooling of these positrons and show that their eventual annihilation with cluster electrons yields a narrow annihilation line. Unlike annihilation in the interstellar medium of galaxies, t

Roberto Aloisio, Pasquale Blasi

The standard calculations of the synchrotron emission from charged particles in magnetic fields does not apply when the energy losses of the particles are so severe that their energy is appreciably degraded during one Larmor rotation. In these conditions, the intensity and spectrum of the emitted radiation depend on the observation time $T_{obs}$: the standa

C. M. Walmsley, R. Bachiller, G. Pineau des Forets, P. Schilke

We have observed the J=5-4 ground state transition of FeO at a frequency of 153 GHz towards a selection of galactic sources. Towards the galactic center source SgrB2, we see weak absorption at approximately the velocity of other features towards this source (62 km s$^{-1}$ LSR). Towards other sources, the results were negative as they were also for MgOH(3-2)

Roberto Aloisio, Pasquale Blasi

Synchrotron emission of relativistic particles in magnetic fields is a process of paramount importance in astrophysics. Although known for over thirty years, there are still aspects of this radiative process that have received little attention, mainly because they appear only in extreme conditions. In the present paper, we first provide a general introductio

T. R. Marsh, D. Steeghs

V407 Vul (= RXJ1914.4+2457) shows pulsations in X-ray flux on a period of 9.5 minutes, which have been ascribed to accretion onto a magnetic white dwarf, with the X-ray pulses seen as the accreting pole moves into and out of view. The X-ray flux drops to zero between pulses, and no other periods are seen, suggesting that V407 Vul is a type of system known as

Attila Grandpierre, Gabor Agoston

Linear stability analysis indicates that solar core is thermally stable for infinitesimal internal perturbations. For the first time, thermal metastabilities are found in the solar core when outer perturbations with significant amplitude are present. The obtained results show that hot bubbles generated by outer perturbations may travel a significant distance

M. Ravasio, G. Tagliaferri, G. Ghisellini, P. Giommi

We report on two BeppoSAX observations of BL Lac (2200+420) performed respectively in June and December 1999, as part of a ToO program to monitor blazars in high states of activity. During both runs the source has been detected up to 100 keV, but it showed quite different spectra: in June it was concave with a very hard component above 5-6 keV (alpha_1 ~ 1.6

Noam Soker

I propose a scenario for the formation of double-ring systems, as observed in some planetary nebulae and in the outer rings of SN 1987A. In this scenario, two jets, one jet on each side of the equatorial plane, expand into a thin, dense shell. Such a flow is expected in binary systems where the mass-losing primary undergoes an impulsive mass loss episode whi

F. J. Molster, L. B. F. M. Waters, A. G. G. M. Tielens, C. Koike

We have carried out a quantitative trend analysis of the crystalline silicates observed in the ISO spectra of a sample of 14 stars with different evolutionary backgrounds. We have modeled the spectra using a simple dust radiative transfer model and have correlated the results with other known parameters. We confirm the abundance difference of the crystalline

F. J. Molster, L. B. F. M. Waters, A. G. G. M. Tielens

This is the second paper in a series of three in which we present an exhaustive inventory of the 49 solid state emission bands observed in a sample of 17 oxygen-rich dust shells surrounding evolved stars. Most of these emission bands are concentrated in well defined spectral regions (called complexes). We define 7 of these complexes; the 10, 18, 23, 28, 33,

F. J. Molster, L. B. F. M. Waters, A. G. G. M. Tielens, M. J. Barlow

This is the first paper in a series of three where we present the first comprehensive inventory of solid state emission bands observed in a sample of 17 oxygen-rich circumstellar dust shells surrounding evolved stars. The data were taken with the Short and Long Wavelength Spectrographs on board of the Infrared Space Observatory (ISO) and cover the 2.4 to 195

M. J. Coe, N. J. Haigh, S. G. T. Laycock, I. Negueruela

We report optical and IR observations of the ASCA X-ray pulsar system AX J0051-733. The relationship between the X-ray source and possible optical counterparts is discussed. Long term optical data from over 7 years are presented which reveal both a 1.4d modulation and an unusually rapid change in this possible binary period. Various models are discussed.

K. Hurley

On the average, 1.5 new publications on cosmic gamma-ray bursts enter the literature every day. The total number now exceeds 5300. I describe here a relatively complete bibliography which is on the web, and which can be made available electronically in various formats.

Chul-Sung Choi, Tadayasu Dotani, Heon-Young Chang, Insu Yi

We have studied the long-term X-ray light curve (2$-$10 keV) of the luminous Seyfert 1 galaxy MCG-2-58-22 by compiling data, from various X-ray satellites, which together cover more than 20 years. We have found two distinct types of time variations in the light curve. One is a gradual and secular decrease of the X-ray flux, and the other is the episodic incr

D. H. Hartmann, T. M. Kneiske, K. Mannheim, K. Watanabe

GRBs contribute to the evolving cosmic radiation field. We discuss the contribution of GRBs to the high-energy background, and the effect of pair creation off low-energy photons on their observable TeV spectrum.

J. W. Kruk, J. C. Howk, M. Andre, H. W. Moos

We present an analysis of interstellar absorption along the line of sight to the nearby white dwarf star HZ43A. The distance to this star is 68+/-13 pc, and the line of sight extends toward the north Galactic pole. Column densities of OI, NI, and NII were derived from spectra obtained by the Far Ultraviolet Spectroscopic Explorer (FUSE), the column density o

R. Dodson, S. P. Ellingsen, M. A. Voronkov

We have used the Australia Telescope Compact Array (ATCA) to make a sensitive (5-$σ$ $\simeq$ 100 mJy) search for maser emission from the 4765-MHz $^2Π_{1/2}$ F=1$\to$0 transition of OH. Fifty five star formation regions were searched and maser emission with a peak flux density in excess of 100 mJy was detected toward fourteen sites, with ten of these being

M. J. Fitch, J. D. Franson

Nonlocal dispersion cancellation is generalized to frequency-entangled states with large photon number N. We show that the same entangled states can simultaneously exhibit a factor of 1/sqrt(N) reduction in noise below the classical shot noise limit in precise timing applications, as was previously suggested by Giovannetti, Lloyd and Maccone (Nature v412 (20

F. Gabbiani, Jianwei Qiu, G. Valencia

We discuss semileptonic B decays of the form B -> J/Psi e nu X as possible probes of intrinsic charm. We calculate the leading order perturbative contribution to the process B- -> J/Psi e- nu_e X and find it to be unobservably small, with a branching ratio ~ 10^-10. We propose a modified spectator model to estimate the intrinsic charm contribution and find t

M. V. Libanov, E. Ya. Nougaev

In a class of multidimensional models, topology of a thick brane provides three chiral fermionic families with hierarchical masses and mixings in the effective four-dimensional theory, while the full model contains a single vector-like generation. We carry out numerical simulations and reproduce all known Standard Model fermion masses and mixings in one of t

Zvi Bern, Abilio De Freitas, Lance Dixon

We present the two-loop helicity amplitudes for the scattering of two gluons into two gluons in QCD, which are relevant for next-to-next-to-leading order corrections to jet production at hadron colliders. We give the results in the `t Hooft-Veltman and four-dimensional helicity variants of dimensional regularization. Summing our expressions over helicities a

Amruta Mishra, Joachim Reinhardt, Horst Stoecker, Walter Greiner

The in-medium properties of the vector mesons are known to be modified significantly in hot and dense hadronic matter due to vacuum polarisation effects from the baryon sector in the Walecka model. The vector meson mass drops significantly in the medium due to the effects of the Dirac sea. In the variational approach adopted in the present paper, these effec

Amina Helmi, Simon D. M. White, Volker Springel

We study the phase-space structure of a dark-matter halo formed in a high resolution simulation of a Lambda CDM cosmology. Our goal is to quantify how much substructure is left over from the inhomogeneous growth of the halo, and how it may affect the signal in experiments aimed at detecting the dark matter particles directly. If we focus on the equivalent of

Rudy Wijnands, Q. Daniel Wang

We present a Chandra/ACIS-I observation of GRO J1744-28. We detected a source at a position of R.A = 17h 44m 33.09s and Dec. = -28degr 44&#39; 27.0&#39;&#39; (J2000.0; with a 1sigma error of ~0.8 arcseconds), consistent with both ROSAT and interplanetary network localizations of GRO J1744-28 when it was in outburst. This makes it likely that we have detected

Zheng Zheng, Jordi Miralda-Escude

We calculate the column density distribution of damped Lyman alpha systems, modeled as spherical isothermal gaseous halos ionized by the external cosmic background. The effects of self-shielding introduce a hump in this distribution, at a column density N_{HI} \sim 1.6x10^{17} X^{-1} cm^{-2}, where X is the neutral fraction at the radius where self-shielding

M. Widom, R. Mosseri, N. Destainville, F. Bailly

Three-dimensional integer partitions provide a convenient representation of codimension-one three-dimensional random rhombus tilings. Calculating the entropy for such a model is a notoriously difficult problem. We apply transition matrix Monte Carlo simulations to evaluate their entropy with high precision. We consider both free- and fixed-boundary tilings.

A. Ahmedov, G. V. Fedotovich, E. A. Kuraev, Z. K. Silagadze

We consider the $π^+π^-π_0γ$ final state in electron-positron annihilation at cms energies not far from the threshold. Both initial and final state radiations of the hard photon is considered but without interference between them. The amplitude for the final state radiation is obtained by using the effective Wess-Zumino-Witten Lagrangian for pion-photon inte

Valery A. Gritsenko, Viacheslav V. Nikulin

We discuss a general theory of Lorentzian Kac--Moody algebras which should be a hyperbolic analogy of the classical theories of finite-dimensional semi-simple and affine Kac-Moody algebras. First examples of Lorentzian Kac-Moody algebras were found by Borcherds. We consider general finiteness results about the set of Lorentzian Kac--Moody algebras and the pr

Kazumi Okuyama

We show analytically that the ratio of the norm of sliver states agrees with the ratio of D-brane tensions. We find that the correct ratio appears as a twist anomaly.

Yi Liao

A generalization of the standard electroweak model to noncommutative spacetime would involve a product gauge group which is spontaneously broken. Gauge interactions in terms of physical gauge bosons are canonical with respect to massless gauge bosons as required by the exact gauge symmetry, but not so with respect to massive ones; and furthermore they are ge

Mei-Rong Li, E. Orignac

We consider heat transport in a Luttinger liquid (LL) with weak disorder and study the Lorenz number for this system. We start at a high-$T$ regime, and calculate both the electrical and thermal conductivities using a memory function approach. The resulting Lorenz number $L$ is independent of $T$ but depends explicitly on the LL exponents. Lowering $T$, howe

Nicolao Fornengo

This report is a brief review of the efforts to explain the nature of non-baryonic dark matter and of the studies devoted to the search for relic particles. Among the different dark matter candidates, special attention is devoted to relic neutralinos, by giving an overview of the recent calculations of its relic abundance and detection rates in a wide variet

Brandon Carter, Robert H. Brandenberger, Anne-Christine Davis

We discuss various issues related to stabilized embedded strings in a thermal background. In particular, we demonstrate that such strings will generically become superconducting at moderately low temperatures, thus enhancing their stability. We then present a new class of defects - drum vortons - which arise when a small symmetry breaking term is added to th

Christian R. Kaiser, Garret Cotter

Radio relic sources in galaxy clusters are often described as the remnants of powerful radio galaxies. Here we develop a model for the evolution of such relics after the jets cease to supply energy to the lobes. This includes the treatment of a relic overpressured with respect to its gaseous surroundings even after the jets switch off. We also determine the

Jos Uffink

This letter presents quantum mechanical inequalities which distinguish, for systems of $N$ spin-$\half$ particles ($N>2$), between fully entangled states and states in which at most $N-1$ particles are entangled. These inequalities are stronger than those obtained by Gisin and Bechmann-Pasquinucci [Phys.\ Lett. A {\bf 246}, 1 (1998)] and by Seevinck and Svet

J. -M. Caillol, D. Levesque, J. -J. Weis

Reassessment of the critical temperature and density of the restricted primitive model of an ionic fluid by Monte Carlo simulations performed for system sizes with linear dimension up to $L/σ=34$ and sampling of $\sim 10^9$ trial moves leads to $T^*_c=0.04917 \pm 0.00002$ and $ρ_c^* =0.080 \pm 0.005$. Finite size scaling analysis based in the Bruce-Wilding p

J. V. Alvarez, Claudius Gros

We study the thermal transport properties of several quantum spin chains and ladders. We find indications for a diverging thermal conductivity at finite temperatures for the models examined. The temperature at which the non-diverging prefactor κ^{(th)}(T) peaks is in general substantially lower than the temperature at which the corresponding specific heat c_

Yvonne Choquet-Bruhat, Spiros Cotsakis

We prove global hyperbolicity of spacetimes under generic regularity conditions on the metric. We then show that these spacetimes are timelike and null geodesically complete if the gradient of the lapse and the extrinsic curvature $K$ are integrable. This last condition is required only for the tracefree part of $K$ if the universe is expanding.

B. Mohanty, D. P. Mahapatra, T. K. Nayak

We show that an event-by-event fluctuation of the ratio of neutral pions or resulting photons to charged pions can be used as an effective probe for the formation of disoriented chiral condensates. The fact that the neutral pion fraction produced in case of disoriented chiral condensate formation has a characteristic extended non gaussian shape, is shown to

Jinhyoung Lee, Hyegeun Min, Sung Dahm Oh

The scheme for entanglement teleportation is proposed to incorporate multipartite entanglement of four qubits as a quantum channel. Based on the invariance of entanglement teleportation under arbitrary two-qubit unitary transformation, we derive relations of separabilities for joint measurements at a sending station and for unitary operations at a receiving