April 1999 arXiv papers — page 7

CMD2 Collaboration

First results of the study of the process e+e- \to 4πby the CMD-2 collaboration at VEPP-2M are presented for the energy range 1.05--1.38 GeV. Using an integrated luminosity of 5.8 pb^{-1}, energy dependence of the processes e+e- \to π^+π^- 2π^0 and e+e- \to 2π^+ 2π^- has been measured. Analysis of the differential distributions demonstrates the dominance of

G. Lazarides

The nonsupersymmetric as well as the supersymmetric hybrid inflationary model is reviewed. The scenario of baryogenesis via a primordial leptogenesis is discussed and the role of the nonperturbative electroweak sphaleron effects is analyzed. A supersymmetric model based on a left-right symmetric gauge group, which `naturally' leads to hybrid inflation, i

Simon Portegies Zwart, Lev Yungelson

We discuss the formation of pulsars with massive companions in eccentric orbits. We demonstrate that the probability for a non-recycled radio pulsar to have a white dwarf as a companion is comparable to that of having an old neutron star as a companion. Special emphasis is given to PSR B1820-11 and PSR B2303+46. Based on population synthesis calculations we

Dirk Helbing, Illes Farkas, Tamas Vicsek

We investigate a simple model corresponding to particles driven in opposite directions and interacting via a repulsive potential. The particles move off-lattice on a periodic strip and are subject to random forces as well. We show that this model - which can be considered as a continuum version of some driven diffusive systems - exhibits a paradoxial, new ki

C. Hofman, J. -S. Park

We describe a class of supersymmetric gauged linear sigma-model, whose target space is the infinite dimensional space of bundles on a Calabi-Yau 3- or 2-fold. This target space can be considered the configuration space of D-branes wrapped around the Calabi-Yau. We propose that this model can be used to define matrix string theory compactifications. In the in

Ken Sekimoto, Fumiko Takagi, Tsuyoshi Hondou

We employ the recently developed framework of the energetics of stochastic processes (called `stochastic energetics'), to re-analyze the Carnot cycle in detail, taking account of fluctuations, without taking the thermodynamic limit. We find that both processes of connection to and disconnection from heat baths and adiabatic processes that cause distortio

E. Bedulev, E. Viehweg

For a non-isotrivial family of surfaces of general type over a complex projective curve, we give upper bounds for the degree of the direct images of powers of the relative dualizing sheaf. They imply that, fixing the curve and the possible degeneration locus, the induced morphisms to the moduli scheme of stable surfaces of general type are parameterized by a

P. Valageas

In this article we present an analytic calculation of the probability distribution of the magnification of distant sources due to weak gravitational lensing from non-linear scales. We use a realistic description of the non-linear density field, which has already been compared with numerical simulations. Then, we can directly express the p.d.f. $P(μ)$ of the

Maki Sekiguchi, Masataka Fukugita

We attempt to construct a B-V colour temperature relation for stars in the least model dependent way employing the best modern data. The fit we obtained with the form Teff = Teff((B-V)0,[Fe/H],log g) is well constrained and a number of tests show the consistency of the procedures for the fit. Our relation covers from F0 to K5 stars with metallicity [Fe/H] =

Eliot Fried, Shaun Sellers

A generalized continuum framework for the theory of solute transport in fluids is proposed and systematically developed. This framework rests on the introduction of a generic force balance for the solute, a balance distinct from the macroscopic momentum balance associated with the mixture. Special forms of such a force balance have been proposed and used goi

Angelica de Oliveira-Costa, Max Tegmark, Carlos M. Gutierrez, Aled W. Jones

The recent discovery of dust-correlated diffuse microwave emission has prompted two rival explanations: free-free emission and spinning dust grains. We present new detections of this component at 10 and 15 GHz by the switched-beam Tenerife experiment. The data show a turnover in the spectrum and thereby supports the spinning dust hypothesis. We also present

Elena Celledoni, Arieh Iserles

Discretization methods for ordinary differential equations based on the use of matrix exponentials have been known for decades. This set of ideas has come off age and acquired greater urgency recently, within the context of geometric integration and discretization methods on manifolds based on the use of Lie-group actions. In the present paper we study the a

Hans J. Wospakrik

We present an explicit path integral evaluation of the free Hamiltonian propagator on the (D-1)-dimensional pseudosphere, in the horicyclic coordinates, using the integral equation method. This method consists in deriving an integral equation for the propagator that turns out to be of Abel's type.

Hein Roehrig

Withdrawn by the author due to irreparable errors. We present a quantum algorithm that in the black-box model performs a search in an ordered list of N elements. Using 3/4 log N + O(1) queries, it achieves a success probability of at least 1/2, whereas classically, log N - O(1) queries are needed to obtain constant success probability. Moreover, our algorith

David A. Brown

One can access the space-time development of a heavy-ion reaction directly by imaging the source function from two particle correlation functions. In the case of like-charged pions, this imaging can be recast as a Fourier inversion problem. We will demonstrate how this inversion can be performed on full three-dimensional (i.e. in long, side and out coordinat

H. Kamada, D. Hueber, A. Nogga

In Faddeev calculations of ^3Hwe study the dependence of the binding on the three nucleon force. We adopt the 2 pi -exchange Tucson-Melbourne three-nucleon force and investigate phenomenologically the dependence on the strength of the individual three-body force operators (a -, b -, c - and d -terms). While the a -term provides a tiny contribution the b - an

Y. Nara, N. Otuka, A. Ohnishi, K. Niita

A hadronic cascade model based on resonances and strings is used to study mass dependence of relativistic nuclear collisions from p+Be to Au+Au at AGS energies ($\sim 10\AGeV$) systematically. Hadron transverse momentum and rapidity distributions obtained with both cascade calculations and Glauber type calculations are compared with experimental data to perf

Jerry Lodder

In this paper we study the variability and rigidity of secondary characteristic classes which arise from flat connections on a manifold. Considering the connection as a Lie-algebra valued one-form, we study the characteristic map from Lie algebra cohomology to de Rham cohomology of the manifold, and prove that if the Leibniz cohomology of the Lie algebra van

C. Binnenhei

The representations of a group of gauge automorphisms of the canonical commutation or anticommutation relations which appear on the Hilbert spaces of isometries H_ρimplementing quasi-free endomorphisms ρon Fock space are studied. Such a representation, which characterizes the "charge" of ρin local quantum field theory, is determined by the Fock space

Lev A. Borisov, Anatoly Libgober

The paper contains a proof that elliptic genus of a Calabi-Yau manifold is a Jacobi form, finds in which dimensions the elliptic genus is determined by the Hodge numbers and shows that elliptic genera of a Calabi-Yau hypersurface in a toric variety and its mirror coincide up to sign. The proof of the mirror property is based on the extension of elliptic genu

Mustafa Korkmaz

We prove that every endomorphism of the mapping class group of an orientable surface onto a subgroup of finite index is in fact an automorphism.

P. Bressler, R. Nest, B. Tsygan

We deduce the Riemann-Roch type formula expressing the microlocal Euler class of a perfect complex of D-modules in terms of the Chern character of the associated symbol complex and the Todd class of the manifold from the Riemann-Roch type theorem for periodic cyclic cocycles of a symplectic deformation quantization. The proof of the latter is contained in th

Andrew McLennan

Theorem 1 is a formula expressing the mean number of real roots of a random multihomogeneous system of polynomial equations as a multiple of the mean absolute value of the determinant of a random matrix. Theorem 2 derives closed form expressions for the mean in special cases that include earlier results of Shub and Smale (for the general homogeneous system)

A. J. da Silva

We study the non relativistic limit of a Model of Fermions interacting through a Chern-Simons Field, from a perspective that resembles the Wilson's Renormalization Group approach, instead of the more usual approach found in most texts of Field Theory. The solution of some difficulties, and a new understanding of non relativistic models is given.

Andrea Gregori, Costas Kounnas

We investigate the connections between four-dimensional, N=2 M-theory vacua constructed as orbifolds of type II, heterotic, and type I strings. All these models have the same massless spectrum, which contains an equal number of vector multiplets and hypermultiplets, with a gauge group of the maximal rank allowed in a perturbative heterotic string constructio

Yu. A. Simonov

The asymptotics of n-point Green's function at large external momenta is obtained in the exponentiated form using the Fock-Feynman-Schwinger representation for propagators in the external field. The method is applied to gauge theories such as QCD and QED, and the Sudakov form-factor is calculated as an example in QED and meson form-factor in QCD. Nonpert

G. Lopez Castro, G. Toledo Sanchez

We study the possibility that the magnetic dipole moment of light charged vector mesons could be measured from their effects in τ^- --> V^-ν_τγdecays. We conclude that the energy spectrum and angular distribution of photons emitted at small angles with respect to vector mesons is sensitive the effects of the magnetic dipole moment. Model-dependent contributi

A. Ali

We review the information on the CKM matrix elements, unitarity triangle and CP-violating phases $α, β$ and $γ$ in the standard model which will be measured in the forthcoming experiments at B factories, HERA-B and hadron colliders. We also discuss two-body non-leptonic decays $B \to h_1 h_2$, with $h_i$ being light mesons, which are interesting from the poi

K. -I. Izawa, T. Yanagida

We consider an inflationary scenario where the energy scale of inflation stems from gauge theory dynamics. We point out its generic implications on vacuum selection of our universe, in particular, on determination of spacetime symmetries including its dimensions.

B. K. Patra, V. J. Menon

We comment on the paper hep-ph/9701265.

B. K. Patra, V. J. Menon, C. P. Singh

We have examined the efficiency of baryon-number transport mechanism across the phase boundary in a cosmological quark-hadron phase transition through the proper estimate of baryon-number penetrability $<Σ_h>$. For this purpose we have derived first the double-pair creation probability $P_b$ in terms of single-pair creation probabilty per unit time and unit

S. Tkaczyk, The CDF Collaboration

The CDF Collaboration has adapted several heavy flavor tagging techniques and employed them in analyses of time-dependent flavor asymmetries using data from the Tevatron Run I. The tagging algorithms were calibrated using low-P_t inclusive lepton and dilepton trigger data samples. The tagging techniques were applied to a sample of \sim 400 B^0_d/B-bar^0_d ->

Thibault Damour

The confrontation between Einstein&#39;s gravitation theory and experimental results, notably binary pulsar data, is summarized and its significance discussed. Experiment and theory agree at the 10^{-3} level or better. All the basic structures of Einstein&#39;s theory (coupling of gravity to matter; propagation and self-interaction of the gravitational fiel

N. Kumar

As the mass-energy is universally self-gravitating, the gravitational binding energy must be subtracted self-consistently from its bare mass value so as to give the physical gravitational mass. Such a self-consistent gravitational self-energy correction can be made non-perturbatively by the use of a gravitational `charging&#39; technique, where we calculate

Stephen F. Bush, John Hershey, Kirby Vosburgh

The goal of this paper is to define and analyze systems which exhibit brittle behavior. This behavior is characterized by a sudden and steep decline in performance as the system approaches the limits of tolerance. This can be due to input parameters which exceed a specified input, or environmental conditions which exceed specified operating boundaries. An an

Stephen F. Bush, Sunil Jagannath, Joseph B. Evans, Victor Frost

This paper extends a stochastic theory for buffer fill distribution for multiple ``on&#39;&#39; and ``off&#39;&#39; sources to a mobile environment. Queue fill distribution is described by a set of differential equations assuming sources alternate asynchronously between exponentially distributed periods in ``on&#39;&#39; and ``off&#39;&#39; states. This pape

Stephen F. Bush, Sunil Jagannath, Joseph B. Evans, Victor Frost

This paper describes the design of a control and management network (orderwire) for a mobile wireless Asynchronous Transfer Mode (ATM) network. This mobile wireless ATM network is part of the Rapidly Deployable Radio Network (RDRN). The orderwire system consists of a packet radio network which overlays the mobile wireless ATM network, each network element in

L. Gutman, E. I. Shakhnovich

Phase separation of sequence-disordered liquid crystalline polymers, a promising class of technological and biological relevance, is studied by field theory, and thermodynamic mechanisms responsible for orientational ordering observed in experiments, are discussed. The theory developed predicts that chemical disorder marginally affects the nematic/isotropic

S. H. Chun, M. B. Salamon, P. D. Han, Y. Lyanda-Geller

As in conventional ferromagnets, the Hall resistivity rho_xy of a La_{2/3}(Ca,Pb)_{1/3}MnO_3 single crystal exhibits both ordinary and anomalous contributions at low temperature. However, these contributions, unexpectedly, have opposite signs. Near Tc, the ordinary contribution is no longer evident and rho_xy is solely determined by the sample magnetization,

Y. Lyanda-Geller, P. M. Goldbart, S. H. Chun, M. B. Salamon

A microscopic picture of charge transport in manganites is developed, with particular attention being paid to the neighborhood of the ferromagnet-to- paramagnet phase transition. The basic transport mechanism invoked is inelastically-assisted carrier hopping between states localized by magnetic disorder. In the context of the anomalous Hall effect, central r

M. E. Zhitomirsky, T. M. Rice, V. I. Anisimov

A ferromagnet with a small spontaneous moment but with a high Curie temperature can be obtained by doping an excitonic insulator made from a spin triplet exciton condensate. Such a condensate can occur in a semimetal with a small overlap or a semiconductor with a small bandgap. We propose that it is responsible for the unexpected ferromagnetism in the doped

W. Zippold, R. Kuehn, H. Horner

We investigate the non-equilibrium dynamics of spherical spin models with two-spin interactions. For the exactly solvable models of the d-dimensional spherical ferromagnet and the spherical Sherrington-Kirkpatrick model the asymptotic dynamics has for large times and for large waiting times the same formal structure. In the limit of large waiting times we fi

S. De Franceschi, F. Giazotto, F. Beltram, L. Sorba

Complete suppression of the native n-type Schottky barrier is demonstrated in Al/InGaAs(001) junctions grown by molecular-beam-epitaxy. This result was achieved by the insertion of Si bilayers at the metal-semiconductor interface allowing the realization of truly Ohmic non-alloyed contacts in low-doped and low-In content InGaAs/Si/Al junctions. It is shown t

R. Burioni, D. Cassi, L. Donetti

We study the distribution of the complex temperature zeros for the partition function of the Ising model on a Sierpinski gasket using an exact recursive relation. Although the zeros arrange on a curve pinching the real axis at T=0 in the thermodynamic limit, their density vanishes asymptotically along the curve approaching the origin. This phenomenon explain

Enzo Marinari, Giorgio Parisi, Juan J. Ruiz-Lorenzo

We show that the dynamical behavior of the 3D Ising spin glass with Gaussian couplings is not compatible with a droplet dynamics. We show that this is implied from the data of reference cond-mat/9904143, that, when analyzed in an accurate way, give multiple evidences of this fact. Our study is based on the analysis of the overlap-overlap correlation function

M. I. Marques, J. A. Gonzalo

Self-averaging of singular thermodynamic quantities at criticality for randomly and thermally diluted three dimensional Ising systems has been studied by the Monte Carlo approach. Substantially improved self-averaging is obtained for critically clustered (critically thermally diluted) vacancy distributions in comparison with the observed self-averaging for p

Michele Fabrizio, Alexander O. Gogolin, Alexander A. Nersesyan

We derive the phase diagram for the one-dimensional model of a ferroelectric perovskite recently introduced by Egami, Ishihara and Tachiki [Science, {\bf 261}, 1307 (1993)]. We show that the interplay between covalency, ionicity and strong correlations results in a spontaneously dimerized phase which separates the weak-coupling band insulator from the strong

G. Khaliullin, R. Kilian

The interplay between spin and orbital degrees of freedom in the Mott-Hubbard insulator is studied by considering an orbitally degenerate superexchange model. We argue that orbital order and the orbital excitation gap in this model are generated through the order-from-disorder mechanism known previously from frustrated spin models. We propose that the orbita

R. Kilian, G. Khaliullin

The metal-insulator transition in manganites is strongly influenced by the concentration of holes present in the system. Based upon an orbitally degenerate Mott-Hubbard model we analyze two possible localization scenarios to account for this doping dependence: First, we rule out that the transition is initiated by a disorder-order crossover in the orbital se

R. Kilian, S. Krivenko, G. Khaliullin, P. Fulde

We present a theory of magnetic (S=1) Ni and nonmagnetic Zn impurities in underdoped cuprates. Both types of impurities are shown to induce S=1/2 moments on Cu sites in the proximity of the impurity, a process which is intimately related to the spin gap phenomenon in cuprates. Below a characteristic Kondo temperature, the Ni spin is partially screened by the

R. Egger, A. Komnik, H. Saleur

We investigate consequences of adding irrelevant (or less relevant) boundary operators to a (1+1)-dimensional field theory, using the Ising and the boundary sine-Gordon model as examples. In the integrable case, irrelevant perturbations are shown to multiply reflection matrices by CDD factors: the low-energy behavior is not changed, while various high-energy

W. Li, X. Cai

Interaction strength is introduced in a model of evolution in d-dimension space. It is realized by imposing a constraint concerning 2d differences of fitnesses between that of any extremal site and those of its 2d nearest neighbours at each time step in the evolution of the model. For any given interaction strength between 0 and 1 the model can self-organize

Indrani Bose, Emily Chattopadhyay

Recent experiments on the quasi-1D antiferromagnets $R_{2}BaNiO_{5}$ (R = rare earth) have shown the existence of purely 1D Haldane gap excitations propagating on the Ni chains. Below an ordering temperature, the gap excitations survive and coexist with the conventional spin waves in the ordered phase. We construct a model mixed-spin system in 2D for which t

Yoshihiro ASAI

We have studied the ground state of the two-dimensional (2D) Hubbard model by using a quantum monte method paying special attention to the shell structure effect on finite size clusters. Our calculations show there is a gap for spin excitations in the ground state and incommensurate peaks at $(π\pm δ, π)$ and $(π, π\pm δ)$ in the spin correlation function fo

Congjun Wu, Bin Chen, Xi Dai, Yue Yu

The Schwinger boson mean field theory is applied to the quantum ferrimagnetic Heisenberg chain. There is a ferrimagnetic long range order in the ground state. We observe two branches of the low lying excitation and calculate the spin reduction, the gap of the antiferromagnetic branch, and the spin fluctuation at $T=0K$. These results agree with the establish

Vadim Gulyaev

In this paper, a technique for constructing quasiperiodic structures is suggested, which allows one by the assigned matching to restore the atoms density distribution formula of a corresponding quasicrystal. The algorithm to restore the atom density distribution has been considered on the example of the Penrose matching. The analytical record of a Penrose qu

A. M. F. Rivas, M. Saraceno, A. M. Ozorio de Almeida

In this work we study cat maps with many degrees of freedom. Classical cat maps are classified using the Cayley parametrization of symplectic matrices and the closely associated center and chord generating functions. Particular attention is dedicated to loxodromic behavior, which is a new feature of two-dimensional maps. The maps are then quantized using a r

J. Main, G. Wunner

Densities of states weighted with the diagonal matrix elements of two operators A and B, i.e., rho^(A,B)(E) = sum_n <n|A|n><n|B|n> delta(E-E_n) cannot, in general, be written as a trace formula, and therefore no simple extension of semiclassical trace formulas is known for this case. However, from the high resolution analysis of quantum spectra in the semicl

Eduardo G. Vergini, Gabriel Carlo

We apply a recently developed semiclassical theory of short peridic orbits to the stadium billiard. We give explicit expresions for the resonances of periodic orbits and for the application of the semiclassical Hamiltonian operator to them. Then, by using the 3 shortest periodic orbits and 2 more living in the bouncing ball region, we obtain the first 25 odd

Eduardo G. Vergini

We have developed a semiclassical theory of short periodic orbits to obtain all quantum information of a bounded chaotic Hamiltonian system. If T_1 is the period of the shortest periodic orbit, T_2 the period of the next one and so on, the number N_p.o. of periodic orbits required in the calculation is such that T_1+...+T_N_{p.o} is approximately T_H, with T

G. V. Vlasov

A particular example of chaos can be conceived in the interaction of non-linear oscillator with a harmonic gravitational wave. When we replace the linear potential forces by the therm SIN(x), the type of solution becomes subject to external perturbation. Although the perturbation produced by the gravitational wave is weak the standard estimations allow to pr

K. A. Weaver

The cores of active galactic nuclei (AGN) harbor some of the most extreme conditions of matter and energy in the Universe. One of the major goals of high-energy astrophysics is to probe these extreme environments in the vicinity of supermassive black holes, which are intimately linked to the mechanisms that produce the continuum emission in AGN. X-ray studie

Carl H. Gibson

Matter in the universe has become ``dark&#39;&#39; or ``missing&#39;&#39; through misconceptions about the fluid mechanics of gravitational structure formation. Gravitational condensation occurs on non-acoustic density nuclei at the largest Schwarz length scale L_{ST}, L_{SV}, L_{SM}, L_{SD} permitted by turbulence, viscous, or magnetic forces, or by the flu

Paul W. Hodge, Andrew E. Dolphin, Toby R. Smith, Mario Mateo

We have obtained V and I images of the lone globular cluster that belongs to the dwarf Local Group irregular galaxy known as WLM. The color-magnitude diagram of the cluster shows that it is a normal old globular cluster with a well-defined giant branch reaching to M_V=-2.5, a horizontal branch at M_V=+0.5, and a sub-giant branch extending to our photometry l

J. J. Blanco-Pillado, Ken D. Olum

The electromagnetic decay and final annihilation of magnetic monopole-antimonopole pairs formed in the early universe has been proposed as a possible mechanism to produce the highest energy cosmic rays. We show that for a monopole abundance saturating the Parker limit, the density of magnetic monopolonium formed is many orders of magnitude less than that req

R. Moderski, M. Sikora, T. Bulik

The most luminous GRBs can be explained in terms of models involving stellar mass central engines only if the ejecta are beamed. As was pointed out by Rhoads, the dynamics of the blast wave, formed by the beamed ejecta sweeping the external gas, can be significantly modified by the sideways expansion. This is because in this case the surface of the blast wav

E. J. Copeland, Anupam Mazumdar, N. J. Nunes

We obtain a new class of exact cosmological solutions for multi-scalar fields with exponential potentials. We generalize the assisted inflation solutions previously obtained, and demonstrate how they are modified when there exist cross-couplings between the fields, such as occur in supergravity inspired cosmological models.

M. Heydari-Malayeri, V. Charmandaris, L. Deharveng, M. R. Rosa

High-resolution Hubble Space Telescope images have allowed us for the first time to resolve the compact SMC ionized ``blob&#39;&#39; N88A (diameter 3.5 arcsec or 1 pc). This very young HII region, which is hatching from its natal molecular cloud, is heavily affected by absorbing dust associated with the cloud. The interstellar reddening towards N88A is on av

Alan F. Heavens, Ravi K. Sheth

We present accurate predictions of the correlation function of hotspots in the microwave background radiation for gaussian theories such as those predicted in most inflation models. The correlation function of peaks above a certain threshold depends only on the threshold and the power spectrum of temperature fluctuations. Since there are both potentially obs

D. L. Khokhlov

It is assumed that, in the primordial plasma, at the temperatures above the mass of electron, fermions are in the neutral state being the superposition of particle and antiparticle. There exists neutral proton-electron symmetry. Proton-electron equilibrium is defined by the proton-electron mass difference. At the temperature equal to the mass of electron, pa

P. Zycki, C. Done, D. Smith

We re-analyze archival Ginga data of the soft X-ray transient source GS 2023+338 covering the beginning of its May 1989 outburst. The source showed a number of rather unusual features: very high and apparently saturated luminosity, dramatic flux and spectral variability (often on ~1 sec time scale), generally very hard spectrum, with no obvious soft thermal

Kazuyuki Omukai, Ryoichi Nishi

We study the H2 photodissociation regions around OB stars in primordial gas clouds whose virial temperatures are between a few hundred and a few thousand Kelvin. In such small objects, a single O star can photodissociate a mass equal to that of the cloud itself. As a result, the clouds deplete their molecular coolant and cannot cool in a free-fall time, and

N. Neininger, M. Dumke

We have detected extraplanar cold dust at distances out to > 10 kpc, situated in the halo of the interacting galaxy NGC 4631. The dust emission disk is much thinner than the warped HI disk and new structures emerge. In particular, a giant arc has been found that is linked to anomalies in the kinematical structure of the atomic gas. Most of the extraplanar du

Sueli M. Viegas, Marcella Contini, Thierry Contini

The physical conditions in typical starburst galaxies are investigated through critical infrared (IR) line ratios, as previously suggested by Lutz et al. (1998, A&A, 333, L75). The calculations by a composite model which consistently accounts for the coupled effect of shock and photoionization by hot stars definitely fit the observed line ratios of single ob

P. Lanoix, G. Paturel, R. Garnier

After the first release of HIPPARCOS data, Feast & Catchpole gave a new value to the zero-point of the visual Cepheid Period-Luminosity relation based on trigonometric parallaxes. Because of the large uncertainties on these parallaxes, the way in which individual measurements are weighted bears a crucial importance, and the discrepancy they show leads to the

V. Bozza

The traditional perturbative method is applied to the case of gravitational lensing of planetary systems. A complete and detailed description of the structure of caustics for a system with an arbitrary number of planets can be obtained. I have also found precise analytical expressions for microlensing light curves perturbed by the presence of planets.

G. T. van Belle

Reliable prediction of stellar diameters, particularly angular diameters, is a useful and necessary tool for the increasing number of milliarcsecond resolution studies being carried out in the astronomical community. A new and accurate technique of predicting angular sizes is presented for main sequence stars, giant and supergiant stars, and for more evolved

Gui Lu Long, Wei Lin Zhang, Yan Song Li, Li Niu

A misunderstanding that an arbitrary phase rotation of the marked state together with the inversion about average operation in Grover's search algorithm can be used to construct a (less efficient) quantum search algorithm is cleared. The $\pi$ rotation of the phase of the marked state is not only the choice for efficiency, but also vital in Grover's quantum

D. Hinzke, U. Nowak, D. A. Garanin

We simulated the field-dependent magnetization m(H,T) and the uniform susceptibility χ(H,T) of classical Heisenberg antiferromagnets in the chain and square-lattice geometry using Monte Carlo methods. The results confirm the singular behavior of χ(H,T) at small T,H: \lim_{T \to 0}\lim_{H \to 0} χ(H,T)=1/(2J_0)(1-1/D) and \lim_{H \to 0}\lim_{T \to 0} χ(H,T)=1

R. Ehrlich

Recently we presented a model to fit the cosmic ray spectrum using the hypothesis that the electron neutrino is a tachyon. The model predicted the existence of a neutron flux in the cosmic rays in a narrow region centered on E = 4.5 +/- 2.2 PeV. The published literature on Cygnus X-3 reveals just such a $6σ$ spike of neutral particles centered on E = 4.5 PeV

Marcus Spradlin, Andrew Strominger

An AdS_2 black hole spacetime is an AdS_2 spacetime together with a preferred choice of time. The Boulware, Hartle-Hawking and SL(2,R) invariant vacua are constructed, together with their Green functions and stress tensors, for both massive and massless scalars in an AdS_2 black hole. The classical Bekenstein-Hawking entropy is found to be independent of the

E. Marinari, F. Zuliani

We present numerical results that allow a precise determination of the transition point and of the critical exponents of the 4D Edwards-Anderson Spin Glass with binary quenched random couplings. We show that the low T phase undergoes Replica Symmetry Breaking. We obtain results on large lattices, up to a volume $V=10^4$: we use finite size scaling to show th

Alex Kovner, J. Guilherme Milhano

We reconsider the evolution equations for multigluon correlators derived in hep-ph/9709432. We show how to derive these equations directly in terms of vector potentials (or colour field strength) avoiding the introduction of the concept of colour charge density in the intermediate steps. The two step procedure of deriving the evolution of the charge density

Satchidananda Naik

We improve the heavy quark potential, extracted from the Wilson loop average in the Ads/CFT approach by taking the quantum fluctuation of the only radial coordinate of $Ads_5$ which is transverse to the world-sheet of the classical Nambu-Goto string in the static gauge, and obtain the universal L{ü}scher-Symanzik-Weisz/L{ü}scher term.

George W. Collins, II, William P. Claspy, John C. Martin

In this paper we re-examine historical references to the supernova event of 1054 AD with a view to establishing a sequence astronomical events which minimizes apparent conflicts between the various sources. We find that the explosion of the supernova is likely to have occurred weeks to months before the commonly accepted date of July 4th 1054. This view is s

G. Bergqvist, J. M. M. Senovilla

By using geometric methods and superenergy tensors, we find new simple criteria for the causal propagation of physical fields in spacetimes of any dimension. The method can be applied easily to many different theories and to arbitrary fields (such as scalar or electromagnetic ones). In particular, it provides a conservation theorem of the free gravitational

Shin&#39;ichi Nojiri, Sergei D. Odintsov

The reduction of 4d matter-gravity theory to $S_2$, $H_2$ or $R_2$ leads to effective 2d dilatonic gravity with dilaton coupled matter. Spinors give the exceptional example of the theory which is conformally invariant in 4d as well as in 2d, after reduction. We find 4d and 2d conformal anomaly induced effective action (EA) for Majorana spinor. It is expected

A. Bodek, Q. Fan, M. Lancaster, K. S. McFarland

A surprisingly large charge symmetry violation of the sea quarks in the nucleon has been proposed in a recent article by Boros et al. as an explanation of the discrepancy between neutrino (CCFR) and muon (NMC) nucleon structure function data at low x. We show that these models are ruled out by the published CDF W charge asymmetry measurements, which strongly

Lauro Moscardini, Sabino Matarrese, Sabrina De Grandi, Francesco Lucchin

We analyse the spatial clustering properties of the RASS1 Bright Sample, an X-ray flux-limited catalogue of galaxy clusters selected from the southern part of the $ROSAT$ All-Sky Survey. The two-point correlation function $ξ(r)$ of the whole sample is well fitted (in an Einstein-de Sitter model) by the power-law $ξ=(r/r_0)^{-γ}$, with $r_0= 21.5^{+3.4}_{-4.4

G. Grispos, A. P. Contogouris, G. Veropoulos

Production of large-p_T hadron pairs by polarized photon on a longitudinally polarized proton towards probing the polarized gluon distribution is studied. Resolved photon contributions and the effect of changing the scales are taken into account, and predictions are presented. A very recent experimental result at c.m. energy 7.18 GeV is compared to our predi

Alexander K. Hartmann

Ground states of four-dimensional (d=4) EA Ising spin glasses are calculated for sizes up to 7x7x7x7 using a combination of a genetic algorithm and cluster-exact approximation. The ground-state energy of the infinite system is extrapolated as e_0=-2.095(1). The ground-state stiffness (or domain wall) energy D is calculated. A D~L^Θ behavior with Θ=0.65(4) is

Takeshi Chiba

We investigate the validity of Thorne&#39;s hoop conjecture in non-axisymmetric spacetimes by examining the formation of apparent horizons numerically. If spaces have a discrete symmetry about one axis, we can specify the boundary conditions to determine an apparent horizon even in non-axisymmetric spaces. We implement, for the first time, the ``hoop finder&

J. Böckenhauer, D. E. Evans, Y. Kawahigashi

We consider a type III subfactor $N\subset M$ of finite index with a finite system of braided $N$-$N$ morphisms which includes the irreducible constituents of the dual canonical endomorphism. We apply $α$-induction and, developing further some ideas of Ocneanu, we define chiral generators for the double triangle algebra. Using a new concept of intertwining b

Volodymyr Lyubashenko

We discuss an example of a triangulated Hopf category related to SL(2). It is an equivariant derived category equipped with multiplication and comultiplication functors and structure isomorphisms. We prove some coherence equations for structure isomorphisms. In particular, the Hopf category is monoidal.

Kedar Damle, Olexei Motrunich, David A. Huse

We present the first results on the low-frequency dynamical and transport properties of random antiferromagnetic spin chains at low temperature ($T$). We obtain the momentum and frequency dependent dynamic structure factor in the Random Singlet (RS) phases of both spin-1/2 and spin-1 chains, as well as in the Random Dimer phase of spin-1/2 chains. We also sh

A. V. Filippenko, D. C. Leonard, T. Matheson, W. Li

We have obtained 17 moderate-resolution (~2.5 A) optical spectra of the Galactic X-ray Nova Velorum 1993 in quiescence with the Keck-II telescope. The orbital period (P) is 0.285206 +/- 0.0000014 d, and the semiamplitude (K_2) is 475.4 +/- 5.9 km/s. Our derived mass function, f(M_1) = PK_2^3 /2 pi G = 3.17 +/- 0.12 M_sun, is close to the conventional absolut

S. Pascazio, P. Facchi

We study the temporal behavior of a three-level system (such as an atom or a molecule), initially prepared in an excited state, bathed in a laser field tuned at the transition frequency of the other level. We analyze the dependence of the lifetime of the initial state on the intensity of the laser field. The phenomenon we discuss is related to both electroma

Caroline H. Thompson

In some key Bell experiments, including two of the well-known ones by Alain Aspect, 1981-2, it is only after the subtraction of ``accidentals&#39;&#39; from the coincidence counts that we get violations of Bell tests. The data adjustment, producing increases of up to 60% in the test statistics, has never been adequately justified. Few published experiments g

Antonina N. Fedorova, Michael G. Zeitlin

In this series of eight papers we present the applications of methods from wavelet analysis to polynomial approximations for a number of accelerator physics problems. In this part we consider variational wavelet approach for loops, invariant bases on semidirect product, KAM calculation via FWT.

Antonina N. Fedorova, Michael G. Zeitlin

In this series of eight papers we present the applications of methods from wavelet analysis to polynomial approximations for a number of accelerator physics problems. In this paper we consider invariant formulation of nonlinear (Lagrangian or Hamiltonian) dynamics on semidirect structure (relativity or dynamical groups) and corresponding invariant calculatio