arXiv papers from August 2001

M. Grayson, L. B. Rigal, D. C. Schmadel, H. D. Drew

We measure the temperature and frequency dependence of the complex Hall angle for normal state YBa$_2$Cu$_3$O$_7$ films from dc to far-infrared frequencies (20-250 cm$^{-1}$) using a new modulated polarization technique. We determine that the functional dependence of the Hall angle on scattering does not fit the expected Lorentzian response. We find spectral

Alex J. Levine, F. C. MacKintosh

We determine both the in-plane and out-of-plane dynamics of viscoelastic membranes separating two viscous fluids in order to understand microrheological studies of such membranes. We demonstrate the general viscoelastic signatures in the dynamics of shear, bending, and compression modes. We also find a screening of the otherwise two-dimensional character of

M. Markevitch, A. Vikhlinin, P. Mazzotta

Chandra data on A1795 reveal a mild edge-shaped discontinuity in the gas density and temperature in the southern sector of the cluster at r=60/h kpc. The gas inside the edge is 1.3-1.5 times denser and cooler than outside, while the pressure is continuous, indicating that this is a "cold front", the surface of contact between two moving gases. The continuity

M. Cvetic, G. W. Gibbons, H. Lu, C. N. Pope

In this paper, we look for metrics of cohomogeneity one in D=8 and D=7 dimensions with Spin(7) and G_2 holonomy respectively. In D=8, we first consider the case of principal orbits that are S^7, viewed as an S^3 bundle over S^4 with triaxial squashing of the S^3 fibres. This gives a more general system of first-order equations for Spin(7) holonomy than has b

Sung Joon Moon, M. D. Shattuck, C. Bizon, Daniel I. Goldman

We use inelastic hard sphere molecular dynamics simulations and laboratory experiments to study patterns in vertically oscillated granular layers. The simulations and experiments reveal that {\em phase bubbles} spontaneously nucleate in the patterns when the container acceleration amplitude exceeds a critical value, about $7g$, where the pattern is approxima

G. -S. Paraoanu, S. Kohler, F. Sols, A. J. Leggett

We study the Josephson effect in alkali atomic gases within the two-mode approximation and show that there is a correspondence between the Bogoliubov description and the harmonic limit of the phase representation. We demonstrate that the quanta of the Josephson plasmon can be identified with the Bogoliubov excitations of the two-site Bose fluid. We thus esta

Joel Giedt

General features of the spectra of matter states in all 175 models found in a previous work by the author are discussed. Only twenty patterns of representations are found to occur. Accomodation of the Minimal Supersymmetric Standard Model (MSSM) spectrum is addressed. States beyond those contained in the MSSM and nonstandard hypercharge normalization are sho

Sergio E. Jorás, Victor H. Cárdenas

We show evidence for a relationship between chaos and parametric resonance both in a classical system and in the semiclassical process of particle creation. We apply our considerations in a toy model for preheating after inflation.

T. R. Hurd

We propose a method for extending a given asset pricing formula to account for two additional sources of risk: the risk associated with future changes in market--calibrated parameters and the remaining risk associated with idiosyncratic variations in the individual assets described by the formula. The paper makes simple and natural assumptions for how these

T. E. Clark, S. T. Love, S. R. Nowling

The superspace Lagrangian formulation of N=1 supersymmetric quantum mechanics is presented. The general Lagrangian constructed out of chiral and antichiral supercoordinates containing up to two derivatives and with a canonically normalized kinetic energy term describes the motion of a nonrelativistic spin 1/2 particle with Land\'e g-factor 2 moving in two sp

R. Somma, G. Ortiz, J. E. Gubernatis, E. Knill

Physical systems, characterized by an ensemble of interacting elementary constituents, can be represented and studied by different algebras of observables or operators. For example, a fully polarized electronic system can be investigated by means of the algebra generated by the usual fermionic creation and annihilation operators, or by using the algebra of P

D0 collaboration, V. M. Abazov

The D0 Collaboration has studied for the first time the properties of hadron-collider jets reconstructed with a successive-combination algorithm based on relative transverse momenta ($k_{\perp}$) of energy clusters. Using the standard value D = 1.0 of the jet-separation parameter in the $k_{\perp}$ algorithm, we find that the $p_T$ of such jets is higher tha

Michael B. Smy

Super-Kamiokande uses neutrino-electron elastic scattering to measure the recoil electron spectrum and zenith-angle dependence of solar $^8$B neutrinos. SNO has measured the $^8$B neutrino--deuteron charged-current reaction rate. The elastic scattering rate, spectrum and zenith-angle dependence in conjunction with the charged-current reaction rate favors act

Kenji Fukushima, Koichi Ohta

The Casimir force has its origin in finite modification of the infinite zero-point energy induced by a specific boundary condition for the spatial configuration. In terms of the imaginary-time formalism at finite temperature, the root of Planck's law of radiation can be traced back to finite modification of the infinite vacuum energy induced by the periodic

Maarten Golterman, Elisabetta Pallante

We summarize some of the difficulties that confront lattice calculations of non-leptonic kaon decay matrix elements. We review some of the methods that have been proposed to overcome these difficulties, and discuss the importance of one-loop ChPT in this respect, including the role of O(p^4) operators.

Dirk Helbing, Davide Batic, Martin Schoenhof, Martin Treiber

Traffic flow at low densities (free traffic) is characterized by a quasi-one-dimensional relation between traffic flow and vehicle density, while no such fundamental diagram exists for `synchronized' congested traffic flow. Instead, a two-dimensional area of widely scattered flow-density data is observed as a consequence of a complex traffic dynamics. For an

Andrea Romanino, Alessandro Strumia

We study if a sizeable muon electric dipole can arise in supersymmetric frameworks able to account for the tight experimental bounds on sfermion masses, like an appropriate flavor symmetry, or like a flavor-blind mechanism of SUSY breaking (in presence of radiative corrections charchteristic of GUT models, or due to Yukawa couplings of neutrinos in see-saw m

Zbyszek P. Karkuszewski, Krzysztof Sacha, Augusto Smerzi

We study a Bose-Einstein condensate trapped in an asymmetric double well potential. Solutions of the time-independent Gross-Pitaevskii equation reveal intrinsic loops in the energy (or chemical potential) level behavior when the shape of the potential is varied. We investigate the corresponding behavior of the quantum (many-body) energy levels. Applying the

R. R. Landim

We show that the topological massive BF theories can be written as a pure BF term through field redefinitions. The fields are rewritten as power expansion series in the inverse of the mass parameter $m$. We also give a cohomological justification of this expansion through BRST framework. In this approach the BF term can be seen as a topological generator for

U. Baur, O. Brein, W. Hollik, C. Schappacher

We calculate the complete electroweak O(alpha) corrections to pp, pbar p -> l+l- X (l=e, mu) in the Standard Model of electroweak interactions. They comprise weak and photonic virtual one-loop corrections as well as real photon radiation to the parton-level processes q bar q -> gamma,Z -> l+l-. We study in detail the effect of the radiative corrections on th

M. E. J. Newman, I. Jensen, R. M. Ziff

Percolation on two-dimensional small-world networks has been proposed as a model for the spread of plant diseases. In this paper we give an analytic solution of this model using a combination of generating function methods and high-order series expansion. Our solution gives accurate predictions for quantities such as the position of the percolation threshold

Emilia La Nave, H. Eugene Stanley, Francesco Sciortino

We present a numerical analysis for SiO_2 of the fraction of diffusive direction f_diff for temperatures T on both sides of the fragile-to-strong crossover. The T-dependence of f_diff clearly reveals this change in dynamical behavior. We find that for T above the crossover (fragile region) the system is always close to ridges of the potential energy surface

Jose R. Ruiz, D. M. Crenshaw, S. B. Kraemer, G. A. Bower

We present measurements of radial velocities for the narrow-line region gas (NLR) in the Seyfert 2 galaxy Mrk 3 out to ~1 kpc from the nucleus. The observations consist of two datasets, both using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope: 1) An [O III] slitless spectrum with the G430M grating of the inner 3" around the nuc

Alex D Gottlieb

This article examines the relationship between classical and quantum propagation of chaos. (In this context, "chaos" refers to the Boltzmann's Ansatz of molecular disorder, not to chaotic dynamics.) Classical propagation of chaos is shown to occur when quantum systems that propagate quantum molecular chaos are suitably prepared, allowed to evolve without int

Bang-He Li, Tian-Jun Li

In this paper, the symplectic genus for any 2-dimensional class in a 4-manifold admitting a symplectic structure is introduced, and its relation with the minimal genus is studied. It is used to describe which classes in rational and irrational ruled manifolds are realized by connected symplectic surfaces. In particular, we completely determine which classes

C. M. Carballo, C. A. Morales, M. J. Pacifico

We prove that homoclinic classes for a residual set of C^1 vector fields X on closed n-manifolds are maximal transitive and depend continuously on periodic orbit data. In addition, X does not exhibit cycles formed by homoclinic classes. We also prove that a homoclinic class of X is isolated if and only if it is Omega-isolated, and that it is the intersection

D. de Florian, M. Grazzini

We consider the region of small transverse momenta in the production of high-mass systems in hadronic collisions. By using the current knowledge on the infrared behaviour of tree-level and one-loop QCD amplitudes at O(alpha_s^2), we analytically compute the general form of the logarithmically-enhanced contributions up to next-to-next-to-leading logarithmic a

John A. Skinta, Mun-Seog Kim, Thomas R. Lemberger, T. Greibe

We present measurements of the magnetic penetration depth, \lambda^{-2}(T), in Pr_{2-x}Ce_{x}CuO_{4-y} and La_{2-x}Ce_{x}CuO_{4-y} films at three Ce doping levels, x, near optimal. Optimal and overdoped films are qualitatively and quantitatively different from underdoped films. For example, \lambda^{-2}(0) decreases rapidly with underdoping but is roughly co

P. F. Kelly, Terry Pilling

We adopt a physically motivated empirical approach to the characterisation of the distributions of twin and triplet primes within the set of primes, rather than in the set of all natural numbers. Remarkably, the occurrences of twins or triplets in any finite sequence of primes are like fixed-probability random events. The respective probabilities are not con

I. V. Dobrovolska, R. S. Tutik

A new recursion procedure for deriving renormalized perturbation expansions for the one-dimensional anharmonic oscillator is offered. Based upon the $\hbar$-expansions and suitable quantization conditions, the recursion formulae obtained have the same simple form both for ground and excited states and can be easily applied to any renormalization scheme. As a

Elso Drigo Filho, M. A. Candido Ribeiro

A general form for ladder operators is used to construct a method to solve bound-state Schr\"odinger equations. The characteristics of supersymmetry and shape invariance of the system are the start point of the approach. To show the elegance and the utility of the method we use it to obtain energy spectra and eigenfunctions for the one-dimensional harmonic o

Helmut G. Katzgraber, A. P. Young

We present results of Monte Carlo simulations, using parallel tempering, on the three- and four-dimensional Edwards-Anderson Ising spin glass with Gaussian couplings at low temperatures with free boundary conditions. Our results suggest that large-scale low-energy excitations may be space filling. The data implies that the energy of these excitations increas

J. E. Gaustad, P. R. McCullough, W. Rosing, D. Van Buren

We have completed a robotic wide-angle imaging survey of the southern sky (declination less than +15 degrees) at 656.3 nm wavelength, the H-alpha emission line of hydrogen. Each image of the resulting Southern H-Alpha Sky Survey Atlas (SHASSA) covers an area of the sky 13 degrees square at an angular resolution of approximately 0.8 arcminute, and reaches a s

W. A. Hofer

We simulate correlation measurements of entangled photons numerically. The model employed is strictly local. In our model correlations arise from a phase, connecting the electromagnetic fields of the two photons at their separate points of measurement. We sum up coincidences for each pair individually and model the operation of a polarizer beam splitter nume

Valentina Petkova, Jean-Bernard Zuber

This article reviews some recent progress in our understanding of the structure of Rational Conformal Field Theories, based on ideas that originate for a large part in the work of A. Ocneanu. The consistency conditions that generalize modular invariance for a given RCFT in the presence of various types of boundary conditions --open, twisted-- are encoded in

Luiz C. de Albuquerque, R. M. Cavalcanti

We compute the leading radiative correction to the Casimir force between two parallel plates in the $\lambda\Phi^4$ theory. Dirichlet and periodic boundary conditions are considered. A heuristic approach, in which the Casimir energy is computed as the sum of one-loop corrected zero-point energies, is shown to yield incorrect results, but we show how to amend

S. Nussinov, M. V. Purohit

In this paper we discuss some aspects of inclusive decays of charmed mesons and also decays of the $\tau$ lepton into $\nu_\tau + 7\pi$. We find that phase space effects are likely to explain the observed lifetime ratio $\tau(D_s^+) / \tau(D^0)$ = 1.17. In particular one need not appeal to a large annihilation contribution in the inclusive $D^0$ decay which,

Jose Riera

We have performed finite temperature quantum Monte Carlo simulations on the t-Jz model on the square lattice. An on-site potential, representing the effect of external mechanisms, is used to stabilize a state of straight site-centered stripes. We show in the first place that various results of our simulations can be related to features observed in high-Tc su

Gregor Diezemann, Gerald Hinze, Hans Sillescu

Dynamic heterogeneity has often been modeled by assuming that a single-particle observable, fluctuating at a molecular scale, is influenced by its coupling to environmental variables fluctuating on a second, perhaps slower, time scale. Starting from the most simple Gaussian Markov process we model the exchange between 'slow' and 'fast' environments by treati

Steven S. Gubser, Indrajit Mitra

We demonstrate that AdS_5 x T^{pq} is unstable, in the sense of Breitenlohner and Freedman, for unequal p and q. This settles, negatively, the long-standing question of whether the T^{pq} manifolds for unequal p and q might correspond to non-supersymmetric fixed points of the renormalization group. We also show that the AdS_3 x S^7 vacuum of Sugimoto's USp(3

H. -J. Schmidt

For the minimally coupled scalar field in Einstein's theory of gravitation we look for the space of solutions within the class of closed Friedmann universe models. We prove that D = 1 or D > 1, where D is the (fractal) dimension of the set of solutions which can be integrated up to t to infinity. (D > 0 was conjectured by PAGE (1984)). We discuss concepts li

M. R. Gaberdiel, A. Recknagel

A family of conformal boundary states for a free boson on a circle is constructed. The family contains superpositions of conventional U(1)-preserving Neumann and Dirichlet branes, but for general parameter values the boundary states are fundamental and preserve only the conformal symmetry. The relative overlaps satisfy Cardy's condition, and each boundary st

M. M. Aggarwal

Event-by-event fluctuations in the multiplicities of charged particles and photons, and the total transverse energy in 158$\cdot A$ GeV Pb+Pb collisions are studied for a wide range of centralities. For narrow centrality bins the multiplicity and transverse energy distributions are found to be near perfect Gaussians. The effect of detector acceptance on the

Donam Youm

We study the brane world cosmology in the RS2 model where the electric charge varies with time in the manner described by the varying fine-structure constant theory of Bekenstein. We map such varying electric charge cosmology to the dual variable-speed-of-light cosmology by changing system of units. We comment on cosmological implications for such cosmologic

S. Boffi, L. Ya. Glozman, W. Klink, W. Plessas

Results for the proton and neutron electric and magnetic form factors as well asthe nucleon axial and induced pseudoscalar form factors are presented for the chiral constituent quark model based on Goldstone-boson-exchange dynamics. The calculations are performed in a covariant framework using the point-form approach to relativistic quantum mechanics. The di

J. Kroseberg

Recent results on open beauty production in positron-proton collisions at a centre-of-mass energy of 300 GeV are presented. The beauty photoproduction cross section is measured by ZEUS and H1 via the semileptonic decay. Both experiments use the transverse lepton momentum with respect to a jet as an observable. The H1 central silicon vertex detector makes it

Gregor Diezemann

Time-resolved optical lineshapes are calculated using a second-order inhomogeneous cumulant expansion. The calculation shows that in the inhomogeneous limit the optical spectra are determined solely by two-time correlation functions. Therefore, measurements of the Stokes-shift correlation function and the inhomogeneous linewidth cannot provide information ab

Haitham Zaraket

In vacuum, the world-line formalism is an efficient tool for calculating observables in the presence of arbitrary constant external fields. The natural frame of this formalism is the Euclidean space. At finite temperature the analytic continuation to Minkowski space is a subtle task. We study the two point function in scalar QED, and we figure out the proble

D. V. Bandourin, N. B. Skachkov

The artificial neural network approach is used for separation of signals from a single photon $\gamma$ and products of the $\pi^0,\eta, K^0_s$ meson neutral decay channels on the basis of the data from the CMS electromagnetic calorimeter alone. Rejection values for the three types of mesons as a function of single photon selection efficiencies are obtained f

D. V. Bandourin, V. F. Konoplyanikov, N. B. Skachkov

The possibility of separating the $\pi^0, \eta, \omega$ and $K^0_s$ meson background from the signal photons produced directly in $pp$ collisions is analyzed. The rejection factors for two pseudorapidity regions 0.4<\eta<1.0$ and 1.6<\eta<2.0$ and six Et values, 20, 40, 60, 80, 100 and 200 GeV, are calculated for a case when only the calorimeter information

Chiaki Yamaguchi, Yutaka Okabe

We apply a newly proposed Monte Carlo method, the Wang-Landau algorithm, to the study of the three-dimensional antiferromagnetic q-state Potts models on a simple cubic lattice. We systematically study the phase transition of the models with q=3, 4, 5 and 6. We obtain the finite-temperature phase transition for q= 3 and 4, whereas the transition temperature i

S. Baskal, Y. S. Kim

The Wigner rotation is a key word in many branches of physics, chemistry and engineering sciences. It is a group theoretical effect resulting from two Lorentz boosts. The net effect is one boost followed or preceded by a rotation. This rotation can therefore be formulated as a product of three boosts. In relativistic kinematics, it is a rotation in the Loren

Andrea Marini, Giovanni Onida, Rodolfo Del Sole

We present an accurate, first-principles study of the electronic structure and absorption spectrum of bulk copper within Density Functional Theory in the Local Density Approximation (DFT-LDA), including the study of intraband transitions. We construct norm-conserving pseudopotentials (PPs) including the 3d shell (and optionally the underlying 3s and 3p shell

Greg Huey, Reza Tavakol

We study the robustness of the quintessence tracking scenario in the context of more general cosmological models that derive from high-energy physics. We consider the effects of inclusion of multiple scalar fields, corrections to the Hubble expansion law (such as those that arise in brane cosmological models), and potentials that decay with expansion of the

Stefano Capitani

Using lattice overlap fermions, we have computed the 1-loop renormalization factors of several operators that measure DIS structure functions and weak amplitudes. Computer codes written in the algebraic manipulation language FORM have been used. The improvement of the operators is also discussed.

N. Mankoc Borstnik, H. B. Nielsen

We propose a possible answer to one of the most exciting open questions in physics and cosmology, that is the question why we seem to experience four- dimensional space-time with three ordinary and one time dimensions. We have known for more than 70 years that (elementary) particles have spin degrees of freedom, we also know that besides spin they also have

L. Gingras, A. Chernomoretz, Y. Larochelle, Z. Y. He

Investigation of intermediate-velocity particle production is performed on entrance channel mass asymmetric collisions of 58Ni+C and 58Ni+Au at 34.5 MeV/nucleon. Distinctions between prompt pre-equilibrium ejections, multiple neck ruptures and an alternative phenomenon of delayed aligned asymmetric breakup is achieved using source reconstructed correlation o

T. Prellberg

Motivated by recent claims of a proof that the length scale exponent for the end-to-end distance scaling of self-avoiding walks is precisely $7/12=0.5833...$, we present results of large-scale simulations of self-avoiding walks and self-avoiding trails with repulsive contact interactions on the hypercubic lattice. We find no evidence to support this claim; o

M. Signore, D. Puy

Over the last decade, cosmological observations have attained a level of precision which allows for very detailed comparison with theoretical predictions. We are beginning to learn the answers to some fundamental questions, using information contained in Cosmic Microwave Background Anisotropy (CMBA) data. In this talk, we briefly review some studies of the c

A. K. Avetissian, K. Z. Hatsagortsian, G. F. Mkrtchian, Kh. V. Sedrakian

A version for intense $\gamma $-ray radiation based on the multiphoton scattering of strong laser radiation on relativistic particle beam channeled in a crystal is proposed. The scheme is considered when the incident laser beam and charged paricles beam are counter-propagating and the laser radiation is resonant to the energy levels of transversal motion of

A. Baldi, S. Molendi, A. Comastri, F. Fiore

We present the first results from an XMM-Newton serendipitous medium-deep survey, which covers nearly three square degrees. We detect a total of 1022, 495 and 100 sources, down to minimum fluxes of about 5.9 x 10^-16, 2.8 x 10^-15 and 6.2 x 10^-15 erg cm^-2 s^-1, in the 0.5-2, 2-10 and 4.5-10 keV band, respectively. In the soft band this is one of the larges

J. Braine, P. -A. Duc, U. Lisenfeld, V. Charmandaris

[Abridged...] We investigate the process of galaxy formation as can be observed in the only currently forming galaxies -- the so-called Tidal Dwarf Galaxies, hereafter TDGs -- through observations of the molecular gas detected via its CO emission. These objects are formed of material torn off of the outer parts of a spiral disk due to tidal forces in a colli

P. J. Heslop

Representations of four dimensional superconformal groups are constructed as fields on many different superspaces, including super Minkowski space, chiral superspace, harmonic superspace and analytic superspace. Any unitary irreducible representation can be given as a field on any one of these spaces if we include fields which transform under supergroups. In

D. Puy, M. Signore

Chemistry plays a particular role in astrophysics. After atomic hydrogen, helium and their ions, the Universe probably contains more mass in molecules than in any other species. Molecule formation in the early, pre-galactic Universe may have had much to do with the formation of galaxies themselves. In this context the possible interaction between primordial

Akira Tomimatsu, Tomoya Matsuoka, Masaaki Takahashi

The screw instability of magnetic field is a mechanism for prohibiting a generation of strongly twisted field lines in large scales. If it can work in black hole magnetospheres, the global axisymmetric structure and the main process of energy release will be significantly influenced. In this paper, we study the instability condition in the framework of the v

A. Chernomoretz, L. Gingras, Y. Larochelle, L. Beaulieu

The particle emission at intermediate velocities in mass asymmetric reactions is studied within the framework of classical molecular dynamics. Two reactions in the Fermi energy domain were modelized, $^{58}$Ni+C and $^{58}$Ni+Au at 34.5 MeV/nucleon. The availability of microscopic correlations at all times allowed a detailed study of the fragment formation p

Stephen Godfrey, M. A. Doncheski

We study the effects of non-commutative QED (NCQED) in fermion pair production, gamma + gamma -> f + bar{f} and Compton scattering, e + gamma -> e + gamma. Non-commutative geometries appear naturally in the context of string/M-theory and gives rise to 3- and 4-point photon vertices and to momentum dependent phase factors in QED vertices which will have obser

S. -W. Lee, J. A. Irwin, R. -J. Dettmar, C. T. Cunningham

We present the first high-resolution study of the disk-halo interface in an edge-on galaxy (NGC 5775) in which every component of the interstellar medium is represented and resolved. New single-dish CO J=2-1 and CO J=1-0 data, ROSAT X-ray data, and HIRES IRAS data are presented along with HI data which emphasizes the high latitude features. In conjunction wi

Gautam Bhattacharyya

Here I briefly discuss why supersymmetry is considered a leading candidate of physics beyond the standard model. I also highlight the salient features of different supersymmetry breaking models. A few other symmetries, broken or intact, asscociated with any realistic supersymmetric model are also identified. This write-up is too simple-minded for an expert o

G. Matt, M. Guainazzi, G. C. Perola, F. Fiore

The bright Narrow Emission Line Galaxy, NGC 5506, has been observed simultaneously by XMM-Newton and BeppoSAX. The iron line is complex, with at least two components: one narrow and corresponding to neutral iron, the second one broad and corresponding to ionized iron. The latter line is equally well fitted by a truly broad line or by a blend of He- and H-lik

S. L. Li, H. H. Wen, Z. W. Zhao

We have measured the magnetic hysteresis loops and the magnetic relaxation for $Bi_2Sr_2CaCu_2O_{8+\delta}$ (Bi-2212) single crystals which exhibit the second magnetization peak effect. Although no second peak effect is observed below 20 K in the measurement with fast field sweeping rate, it is found that the second peak effect will appear again after long t

Jairo Sinova, John Schliemann, Alvaro S. Núñez, A. H. MacDonald

We present a simple tight-binding model for the two-dimensional energy bands of polyacene field-effect transistors and for the coupling of these bands to lattice vibrations of their host molecular crystal. We argue that the strongest electron-phonon interactions in these systems originate from the dependence of inter-molecule hopping amplitudes on collective

Luc Blanchet

We consider the two-body problem in post-Newtonian approximations of general relativity. We report the recent results concerning the equations of motion, and the associated Lagrangian formulation, of compact binary systems, at the third post-Newtonian order (1/c^6 beyond the Newtonian acceleration). These equations are necessary when constructing the theoret

Grigory Mikhalkin

The amoebas associated to algebraic varieties are certain concave regions in the Euclidean space whose shape reminds biological amoebas. This term was formally introduced to Mathematics in 1994 by Gelfand, Kapranov and Zelevinski. Some traces of amoebas were appearing from time to time, even before the formal introduction, as auxiliary tools in several probl

Michele Pavon

Given a positive energy solution of the Klein-Gordon equation, the motion of the free, spinless, relativistic particle is described in a fixed Lorentz frame by a Markov diffusion process with non-constant diffusion coefficient. Proper time is an increasing stochastic process and we derive a probabilistic generalization of the equation $(d\tau)^2=-\frac{1}{c^

C. Wetterich

We investigate if the fluctuations of the scalar field mediating quintessence -- the cosmon -- can play an important role in cosmology. Small fluctuations with short wavelength behave similar to a relativistic gas. In contrast, the contribution to the energy density from horizon size fluctuations may decrease less rapidly than radiation. We discuss the possi

G. L. Israel, T. Oosterbroek, L. Stella, S. Campana

We report on the results of a 50ks BeppoSAX observation of 1RXS J170849-400910, one of the five (plus a candidate) known anomalous X-ray pulsars. The BeppoSAX data are consistent with a power-law plus blackbody spectral decomposition, making 1RXS J170849-400910 the fourth source of this class for which such a spectral decomposition was found. The inferred po

Alberto Bressan, Giuseppe Maria Coclite

The paper is concerned with the boundary controllability of entropy weak solutions to hyperbolic systems of conservation laws. We prove a general result on the asymptotic stabilization of a system near a constant state. On the other hand, we give an example showing that exact controllability in finite time cannot be achieved, in general.

Maria Alberich-Carraminana, Joaquim Roe

We study adjacency of equisingularity types of planar curve singularities in terms of their Enriques diagrams. For linear adjacency a complete answer is obtained, whereas for arbitrary (analytic) adjacency a necessary condition and a sufficient condition are proved. We also show an example of singular curve of type D' that can be deformed to a curve of type

J. J. Binney, N. W. Evans

The microlensing optical depth to Baade's Window constrains the minimum total mass in baryonic matter within the Solar circle to be greater than 3.9 x 10^{10} solar masses, assuming the inner Galaxy is barred with viewing angle of roughly 20 degrees. From the kinematics of solar neighbourhood stars, the local surface density of dark matter is about 30 +/- 15

U. Leonhardt

Laboratory-based optical analogs of astronomical objects such as black holes rely on the creation of light with an extremely low or even vanishing group velocity (slow light). These brief notes represent a pedagogical attempt towards elucidating this extraordinary form of light. This paper is a contribution to the book Artificial Black Holes edited by Mario

M. Bellazzini, F. R. Ferraro, E. Pancino

We present wide field (33 X 34 arcmin^2) multiband (BVI) CCD photometry (down to I <= 20.5) of the very low surface brightness dwarf Spheroidal (dSph) galaxy Sextans. In the derived Color Magnitude Diagrams we have found evidences suggesting the presence of multiple stellar populations in this dSph. In particular we discovered: {\it (i)} a Blue Horizontal Br

Suresh Govindarajan, T. Jayaraman, Tapobrata Sarkar

We construct a linear sigma model for open-strings ending on special Lagrangian cycles of a Calabi-Yau manifold. We illustrate the construction for the cases considered by Aganagic and Vafa in hep-th/0012041. This leads naturally to concrete models for the moduli space of open-string instantons. These instanton moduli spaces can be seen to be intimately rela

C. Bhattacharya, M. Rousseau, C. Beck, V. Rauch

Velocity and energy spectra of the light charged particles (protons and $\alpha$-particles) emitted in the $^{28}$Si(E$_{lab}$ = 112 MeV) + $^{28}$Si reaction have been measured at the Strasbourg VIVITRON Tandem facility. The ICARE charged particle multidetector array was used to obtain exclusive spectra of the light particles in the angular range 15 - 150 d

Bernhard Köck

We give an elementary, self-contained and quick proof of Belyi's theorem. As a by-product of our proof we obtain an explicit bound for the degree of the defining number field of a Belyi surface.

M. E. Prokhorov, S. B. Popov, A. V. Khoperskov

In this paper we present calculations of period distribution for old accreting isolated neutron stars (INSs). After few billion years of evolution low velocity INSs come to the stage of accretion. At this stage INS's period evolution is governed by magnetic braking and angular momentum accreted. Since the interstellar medium is turbulized accreted momentum c

E. Levin, M. Lublinsky

The ratio of the diffractive production to the total cross section in DIS is computed as a function of the produced mass. The analysis is based on the solution to the non-linear evolution equation for the diffraction dissociation in DIS. The obtained ratios almost do not depend on the central mass energy in agreement with the HERA experimental data. This ind

J. N. De, X. Viñas, S. K. Patra, M. Centelles

In a Thomas-Fermi model, calculations are presented for nuclei beyond the nuclear drip line at zero temperature. These nuclei are in equilibrium by the presence of an external gas, as may be envisaged in the astrophysical scenario. We find that there is a limiting asymmetry beyond which these nuclei can no longer be made stable.

V. Sunil Kumar, B. A. Bambah, R. Jagannathan

Four classes of three dimensional quadratic algebras of the type $\lsb Q_0 , Q_\pm \rsb$ $=$ $\pm Q_\pm$, $\lsb Q_+ , Q_- \rsb$ $=$ $aQ_0^2 + bQ_0 + c$, where $(a,b,c)$ are constants or central elements of the algebra, are constructed using a generalization of the well known two-mode bosonic realizations of $su(2)$ and $su(1,1)$. The resulting matrix represe

Torbjörn Sjöstrand, Leif Lönnblad, Stephen Mrenna

The PYTHIA program can be used to generate high-energy-physics `events', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, with emphasis on those where strong interactions play a role, directly or i

E. Ragoucy

We construct embeddings of boundary algebras B into ZF algebras A. Since it is known that these algebras are the relevant ones for the study of quantum integrable systems (with boundaries for B and without for A), this connection allows to make the link between different approaches of the systems with boundaries. The construction uses the well-bred vertex op

Ewelina Lobodzinska

The recent results of the studies of Deeply Virtual Compton Scattering (DVCS) events at HERA are presented. The possibility offered by this process to gain information about skewed parton distributions (SPD) is emphasized.

Yang Chen, Patrick Slane

We present the results from ASCA observations of the centrally enhanced supernova remnant 3C 391 (G31.9+0.0). We use the ASCA SIS data to carry out an investigation of the spatial and spectral properties of the X-ray emission from this remnant. The collisional equilibrium ionization and non-equilibrium ionization spectral fits indicate that the hot gas withi

Satoshi Yamaguchi

We review the enhancon mechanism proposed by Johnson, Peet and Polchinski. If we consider the D6-brane wrapped on K3, then there appear a naked singularity called ``repulson'' in the supergravity solution. But this singularity is resolved by a shell structure called ``enhancon''. In the interior of the enhancon, the abelian gauge symmetry is enhanced to a no

George K. Savvidy

In my talk I shall consider the mechanism of self-expansion of a system of N D0-branes into high-dimensional non-commutative world-volume investigated by Harmark and Savvidy. Here D2-brane is formed due to the internal angular momentum of D0-brane system. The idea is that attractive force of tension should be cancelled by the centrifugal motion preventing a

Takashi Hotta, Elbio Dagotto

The key role of the orbital degree of freedom to understand the magnetic properties of layered ruthenates is here discussed. In the G-type antiferromagnetic phase of Ca$_2$RuO$_4$, recent X-ray experiments reported the presence of 0.5 hole per site in the $d_{xy}$ orbital, while the $d_{\rm yz}$ and $d_{zx}$ orbitals contain 1.5 holes. This unexpected $t_{2g

Jongil Park

In this short article we give a criterion whether a given minimal symplectic 4-manifold with $b_{2}^{+}=1$ having a torsion-free canonical class is rational or ruled. As a corollary, we confirm that most of homotopy elliptic surfaces $E(1}_{K}$, K is a fibered knot in $S^3$, constructed by R. Fintushel and R. Stern are minimal symplectic 4-manifolds with $b_

Dipankar Chattarji, Chiranjib Sur

The problem of angular correlation in the double photoionization (DPI) of rare gas atoms is considered in some depth. We refer particularly to the efficiency operator for the detection of an electron by a detector having cylindrical symmetry. The different factors in the efficiency operator are discussed in detail keeping in mind the fundamental epistemologi

Dario Benedetto, Emanuele Caglioti, Vittorio Loreto

In this letter we present a very general method to extract information from a generic string of characters, e.g. a text, a DNA sequence or a time series. Based on data-compression techniques, its key point is the computation of a suitable measure of the remoteness of two bodies of knowledge. We present the implementation of the method to linguistic motivated

Miyuki K. Shimamura, Tetsuo Deguchi

Anomalously strong finite-size effects have been observed for the mean square radius of gyration $R^2_K$ of Gaussian random polygons with a fixed knot $K$ as a function of the number $N$ of polygonal nodes. Through computer simulations with $N < 2000$, we find for several knots that the gyration radius $R^2_K$ can be approximated by a power law: $R^2_K \sim