May 1999 arXiv papers — page 8

A. Sornette, D. Sornette

Together with the Gutenberg-Richter distribution of earthquake magnitudes, Omori's law is the best established empirical characterization of earthquake sequences and states that the number of smaller earthquakes per unit time triggered by a main shock decays approximately as the inverse of the time ($1/t^p$, with $p \approx 1$) since the main shock. Base

Shoji Yamamoto

Based on a symmetry argument, we study ground states of what we call MMX-chain compounds, which are the new class of halogen-bridged metal complexes. Commensurate density-wave solutions of a relevant multi-band Peierls-Hubbard model are systematically revealed within the Hartree-Fock approximation. We numerically draw ground-state phase diagrams, where vario

Shoji Yamamoto, Toru Sakai

We discuss the critical behavior of the spin-(1,1/2) Heisenberg ferrimagnetic chain in a magnetic field, whose magnetization curve exhibits a plateau at a third of the full magnetization. A bond alternation stabilizes the massive state, whereas an exchange anisotropy causes the breakdown of the plateau and the onset of a gapless spin-fluid state, where the t

K. Takenaka, K. Iida, Y. Sawaki, S. Sugai

Optical reflectivity spectra were measured on cleaved surfaces of La1-xSrxMnO3 single crystals (x=0.175, T_C=283 K) over a temperature range 10-295 K. The optical conductivity $sigma(ω)$ shows, keeping single-component nature, incoherent-to-coherent crossover with increase of electrical conductivity. The $σ(ω)$ spectrum of low-temperature ferromagnetic-metal

Sebastian M. Maurer, Bernardo A. Huberman

We recently presented a methodology for quantitatively reducing the risk and cost of executing electronic transactions in a bursty network environment such as the Internet. In the language of portfolio theory, time to complete a transaction and its variance replace the expected return and risk associated with a security, whereas restart times replace combina

Frank Varosi, Eli Dwek

A Monte Carlo model of radiative transfer in multi-phase dusty media is applied to the situation of stars and clumpy dust in a sphere or a disk. The distribution of escaping and absorbed photons are shown for various filling factors and densities. Analytical methods of approximating the escaping fraction of radiation, based on the Mega-Grains approach, are d

A. J. Barth, A. V. Filippenko, E. C. Moran

In order to determine whether unified models of active galactic nuclei apply to low-luminosity objects, we have undertaken a spectropolarimetric survey of of LINERs and Seyfert nuclei at the Keck Observatory. The 14 objects observed have a median H-alpha luminosity of 8x10^{39} erg/s, well below the typical value of ~10^{41} erg/s for Markarian Seyfert nucle

Kenneth Wood, Ron Reynolds

We present Monte Carlo simulations of the Diffuse H$α$ Galactic Background. Our models comprise direct and multiply scattered H$α$ radiation from the kpc scaleheight Warm Ionized Medium and midplane H II regions. The scattering is off dust that is assumed to be well mixed with the gas, with an axisymmetric density distribution taken from the literature. The

J. Gorosabel, A. J. Castro-Tirado, H. Pedersen, J. Greiner

We report on near-infrared and optical observations of the GRB 970616 error box and of the X-ray sources discovered by ASCA and ROSAT in the region. No optical transient was found either within the IPN band or in the X-ray error boxes, similarly to other bursts, and we suggest that either considerable intrinsic absorption was present (like GRB 970828) or tha

K. L. Luhman

I present new results from a continuing program to identify and characterize the low-mass stellar and substellar populations in the young cluster IC 348 (1-10~Myr). Optical spectroscopy has revealed young objects with spectral types as late as M8.25. The intrinsic J-H and H-K colors of these sources are dwarf-like, whereas the R-I and I-J colors appear inter

K. L. Luhman, G. H. Rieke

We have obtained moderate-resolution (R=800-1200) K-band spectra for ~100 stars within and surrounding the cloud core of rho Oph. We have measured spectral types and continuum veilings and have combined this information with results from new deep imaging. The IMF peaks at about 0.4 M_sun and slowly declines to the hydrogen burning limit with a slope of ~-0.5

Sueli M. Viegas, Amancio C. S. Friaca, Ruth Gruenwald

A hot gas halo is predicted by chemodynamical models during the early evolution of spheroidal galaxies. Cold condensations, arising from thermal instabilities in the hot gas, are expected to be embedded in the hot halo. In the early phases of the galaxy (t < 1 Gyr), a strong X-ray and EUV emission is produced by the extended hot gas distribution, ionizing th

B. E. McArthur, G. F. Benedict, J. Lee, C. -L. Lu

RW Triangulum (RW Tri) is a 13th magnitude Nova-like Cataclysmic Variable star with an orbital period of 0.2319 days (5.56 hours). Infrared observations of RW Tri indicate that its secondary is most likely a late K-dwarf. Past analyses predicted a distance of 270 parsec, derived from a black-body fit to spectrum of the central part of the disk. Recently comp

I. V. Moskalenko, A. W. Strong

We have made a calculation of the propagation of positrons from dark-matter particle annihilation in the Galactic halo in different models of the dark matter halo distribution using our 3D code, and present fits to our numerical propagation Green&#39;s functions. We show that the Green&#39;s functions are not very sensitive to the dark matter distribution fo

G. Leyshon, J. S. Dunlop, Stephen A. Eales

We present the results of K-band imaging polarimetry of three radio galaxies, including the very red and apparently old z=1.55 galaxy 53W091. We find weak evidence for polarization in components of 3C 441 and in the south-east companion of 53W091, but no evidence of significant polarization in 53W091 itself. We also find strong evidence that MRC 0156-252 is

A. Gardini, S. A. Bonometto, G. Murante

We study the cluster mass function in mixed dark matter (MDM) models, using two COBE normalized simulations with Omega_h = 0.26 and n=1.2, and Omega_h = 0.14 and n = 1.05, both with 2 massive nu&#39;s (MDM1 and MDM2, respectively). For the sake of comparison, we also simulate a CDM model with spectral index n=0.8 (TCDM), also COBE normalized. We argue that,

A. Ferrara, E. Tolstoy

Supernova and multiple supernova events regulate several structural properties of dwarf galaxies. In particular, they govern the metal enrichment and the energy budget of the ISM; they might induce partial (blowout) or total (blowaway) gas removal from the galaxy; the morphology of the galactic gaseous body. Significant amounts of dark matter may play an equ

S. Wanajo, M. Hashimoto, K. Nomoto

Nucleosynthesis in ONeMg novae has been investigated with the wide ranges of three parameters, i.e., the white dwarf mass, the envelope mass at ignition, and the initial composition. A quasi-analytic one-zone approach is used with an up-to-date nuclear reaction network. The nucleosynthesis results show correlation with the peak temperatures or the cooling ti

Tsunefumi Mizuno, Tomohisa Ohnishi, Aya Kubota, Kazuo Makishima

The edge-on spiral galaxy NGC 4565 was observed for $\sim$ 35 ks with ASCA in the 0.5-10 keV energy band. The X-ray emission was dominated by two bright sources, which can be identified with two point-like X-ray sources seen in the ROSAT HRI image. The observed 0.5-10 keV fluxes of these sources, $1.7 \times 10^{-12} erg/s cm^{-2}$ and $0.7 \times 10^{-12}er

Andrei Gruzinov

The optical afterglows of the gamma ray bursts can be strongly polarized, in principle up to tens of percents, if: (i) the afterglow is synchrotron radiation from an ultra-relativistic blast, (ii) the blast is beamed during the afterglow phase, i.e. the shock propagates within a narrow jet, (iii) we observe at the right time from the right viewing angle, (iv

E. P. Mazets, T. L. Cline, R. L. Aptekar, P. Butterworth

The results of observations of the giant 1998 August 27 outburst in SGR 1900+14 are presented. A comparison is made of the two extremely intense events on August 27, 1998 and March 5, 1979. The striking similarity between the outbursts strongly implies a common nature. The observation of two giant outbursts within 20 years from different sources suggests tha

Max Tegmark, Daniel J. Eisenstein, Wayne Hu, Angelica de Oliveira-Costa

One of the main challenges facing upcoming CMB experiments will be to distinguish the cosmological signal from foreground contamination. We present a comprehensive treatment of this problem and study how foregrounds degrade the accuracy with which the Boomerang, MAP and Planck experiments can measure cosmological parameters. Our foreground model includes not

M. J. Ramsey-Musolf

We consider the implications of experimental limits on the permanent electric dipole moment (EDM) of the electron and neutron for possible new parity-conserving (PC) time-reversal violating (TV) interactions. We show that the constraints derived from one-loop contributions to the EDM exceed previously reported two-loop limits by more than an order of magnitu

Paolo Piccione, Daniel Victor Tausk

The computation of the index of the Hessian of the action functional in semi-Riemannian geometry at geodesics with two variable endpoints is reduced to the case of a fixed final endpoint. Using this observation, we give an elementary proof of the Morse Index Theorem for Riemannian geodesics with two variable endpoints, in the spirit of the original Morse&#39

T. E. Browder, A. Datta, Patrick. J. O&#39;Donnell, S. Pakvasa

We consider the possibility of measuring both $\sin (2 β)$ and $\cos (2 β)$ in the KM unitarity triangle using the process $B^0 \to D^{*+}D^{*-}K_s$. This decay mode has a higher branching fraction (O(1%)) than the mode $B^0 \to D^{*+}D^{*-}$. We use the factorization assumption and heavy hadron chiral perturbation theory to estimate the branching fraction a

T. Han, D. Rainwater, D. Zeppenfeld

We explore the search sensitivity for signals of large extra dimensions at hadron colliders via the Drell-Yan process pp -> l+ l- + E_T(miss) X (l = e,mu) where the missing transverse energy is the result of escaping Kaluza-Klein gravitons. We find that one is able to place exclusion limits on the gravity scale up to 560 GeV at the Fermilab Tevatron, and to

Seth Lloyd, Jean-Jacques E. Slotine

The problem of feedback control of quantum systems by means of weak measurements is investigated in detail. When weak measurements are made on a set of identical quantum systems, the single-system density matrix can be determined to a high degree of accuracy while affecting each system only slightly. If this information is fed back into the systems by cohere

A. Kehagias, K. Sfetsos

We systematically examine corrections to the gravitational inverse square law, which are due to compactified extra dimensions. We find the induced Yukawa-type potentials for which we calculate the strength αand range. In general the range of the Yukawa correction is given by the wavelength of the lightest Kaluza-Klein state and its strength, relative to the

Sergei Klishevich, Mikhail Plyushchay

We show that the single-mode parafermionic type systems possess supersymmetry, which is based on the symmetry of characteristic functions of the parafermions related to the generalized deformed oscillator of Daskaloyannis et al. The supersymmetry is realized in both unbroken and spontaneously broken phases. As in the case of parabosonic supersymmetry observe

Anindya Datta, Amitava Raychaudhuri

The standard formulation of the Left-Right symmetric model involves scalars transforming as a triplet under SU(2)L. This multiplet contains particles which are uncharged, singly-charged, and doubly-charged. We derive a bound on the uncharged scalar mass of 55.4 GeV using results from LEP-II and find that a range upto 110 GeV may be explored at the NLC at the

G. D&#39;Ambrosio, G. Ecker, G. Isidori, H. Neufeld

We analyse the radiative decay $η\to π^+π^- π^0γ$ in the low--energy expansion of the Standard Model. We employ the notion of ``generalized bremsstrahlung&#39;&#39; to take full advantage of the theoretical and experimental information on the corresponding non-radiative $η\to 3 π$ decay. The direct emission amplitude of ${\cal O}(p^4)$ is due to one-loop dia

E. Ros, J. M. Marcaide, J. C. Guirado, M. I. Ratner

We determined the separations of the radio sources in the triangle formed by the BL Lac objects 1803+784 and 2007+777, and the QSO 1928+738 from intercontinental interferometric observations carried out in November 1991 at the frequencies of 2.3 and 8.4 GHz simultaneously. We successfully connected differenced phase delays over 7^o on the sky at 8.4 GHz at a

Andreas Brandhuber, Yaron Oz

We construct dual Type I&#39; string descriptions to five dimensional supersymmetric fixed points with $E_{N_f+1}$ global symmetry. The background is obtained as the near horizon geometry of the D4-D8 brane system in massive Type IIA supergravity. We use the dual description to deduce some properties of the fixed points.

Yoshio Koide

Stimulated by the phenomenological success of the universal seesaw mass matrix model, where the mass terms for quarks and leptons f_i (i=1,2,3) and hypothetical super-heavy fermions F_i are given by \bar{f}_L m_L F_R +\bar{F}_L m_R f_R + \bar{F}_L M_F F_R + h.c. and the form of M_F is democratic on the bases on which m_L and m_R are diagonal, the following m

R. Boeckmann, C. Hanhart, O. Krehl, S. Krewald

The piNN vertex function is calculated within a dispersion theoretical approach, including both pi-rho and pi-sigma intermediate states, where the sigma meson is an abbreviation for a correlated pion pair in a relative S-wave with isospin I=0. A strong coupling between the pi-sigma and the pi-rho states is found. This leads to a softening of the piNN form fa

B. Alles, J. J. Alonso, C. Criado, M. Pepe

We analyze the percolation properties of certain clusters defined on configurations of the 2--dimensional Heisenberg model. We find that, given any direction \vec{n} in O(3) space, the spins almost perpendicular to \vec{n} form a percolating cluster. This result gives indications of how the model can avoid a previously conjectured Kosterlitz-Thouless phase t

Bodo Geyer, Sergei D. Odintsov, Sergio Zerbini

The formulation of Brans-Dicke (BD) gravity with matter in the Einstein frame is realized as Einstein gravity with dilaton and dilaton coupled matter. We calculate the one-loop 4d anomaly-induced effective action due to N dilaton- coupled massless fermions on the time-dependent conformally flat background with non-trivial dilaton. Using that complete effecti

Joachim Stolze, Michael Vogel

Dynamic autocorrelations $<S_i^α(t) S_i^α>$ (α=x,z) of an isolated impurity spin in a S=1/2 XX chain are calculated. The impurity spin, defined by a local change in the nearest-neighbor coupling, is either in the bulk or at the boundary of the open-ended chain. The exact numerical calculation of the correlations employs the Jordan-Wigner mapping from spin op

C. Ikuta, N. Arimoto

An early history of metal enrichment in the Galactic halo is studied. We investigate chemical inhomogeneity by using a stochastic chemical evolution model. The model confronts with metallicity distribution function of long-lived halo stars which is found to be a clue to obtain the best model prescriptions. We find that the star formation in the halo virtuall

Xiangdong Shi, George M. Fuller, Kevork Abazajian

It has been proposed that an asymmetry in the electron neutrino sector may be generated by resonant active-sterile neutrino transformations during Big Bang Nucleosynthesis (BBN). We calculate the change in the primordial $^4$He yield $Y$ resulting from this asymmetry, taking into account both the time evolution of the $ν_e$ and $\barν_e$ distribution functio

Nalini Joshi, Johannes A. Petersen, Luke M. Schubert

We study characteristic Cauchy problems for the Korteweg-deVries (KdV) equation $u_t=uu_x+u_{xxx}$, and the Kadomtsev-Petviashvili (KP) equation $u_{yy}=\bigl(u_{xxx}+uu_x+u_t\bigr)_x$ with holomorphic initial data possessing nonnegative Taylor coefficients around the origin. For the KdV equation with initial value $u(0,x)=u_0(x)$, we show that there is no s

Rob Clifton, Bradley Monton

Peter Lewis ([1997]) has recently argued that the wavefunction collapse theory of GRW (Ghirardi, Rimini, and Weber [1986]) can only solve the problem of wavefunction tails at the expense of predicting that arithmetic does not apply to ordinary macroscopic objects. More specifically, Lewis argues that the GRW theory must violate the enumeration principle: tha

S. Bruce, J. Diaz-Valdes

The Dirac equation for the Coulomb problem is restated by incorporating a nonlinear effective interaction into the Dirac Hamiltonian: one keeps the $1/r$ dependence for the Coulomb field, but the coupling constant is modified by a factor depending on the n (principal quantum number) power of the mean value of the Hamiltonian. In this simple context we study

N. Gisin

A generalization of the CHSH-Bell inequality to arbitrary many settings is presented. The singlet state of two spin $\half$ violates this inequality for all numbers of setting. In the limit of arbitrarily large number of settings, the violation tends to the finite ratio $4/π\approx 1.27$.

I. M. Savukov, A. Derevianko, H. G. Berry, W. R. Johnson

The influence of negative-energy states (NES) on forbidden magnetic-dipole $ns_{1/2}-(n+1)s_{1/2}$ transitions in alkali-metal atoms is investigated. We find that the NES contributions are significant in almost all cases and for rubidium reduce the transition rate by a factor of 8. We tabulate magnetic-dipole (M_1) transition amplitudes for the alkalis. Our

Andrei N. Berlizov, Alexander A. Zhmudsky

It is shown that MS Fortran-77 compilers allow to construct recursive subroutines. The recursive one-dimensional adaptive quadrature subroutine is considered in particular. Despite its extremely short body (only eleven executable statements) the subroutine proved to be very effective and competitive. It was tested on various rather complex integrands. The po

J. A. Gonzalez, B. A. Mello, L. I. Reyes, L. E. Guerrero

We investigate the dynamics of a soliton that behaves as an extended particle. The soliton motion in an effective bistable potential can be chaotic in a similar way as the Duffing oscillator. We generalize the concept of geometrical resonance to spatiotemporal systems and apply it to design a nonfeedback mechanism of chaos control using localized perturbatio

D. V. Ahluwalia, D. J. Ernst

A pragmatic approach to constructing a covariant phenomenology of the interactions of composite, high-spin hadrons is proposed. Because there are no known wave equations without significant problems, we propose to construct the phenomenology without explicit reference to a wave equation. This is done by constructing the individual pieces of a perturbation th

E. Marco, E. Oset, H. Toki

We study the photoproduction of scalar mesons close to the threshold of f_0(980) and a_0(980) using a unitary chiral model. Peaks for both resonances show up in the invariant mass distributions of pairs of pseudoscalar mesons. A discussion is made on the photoproduction of these resonances in nuclei, which can shed light on their nature, a subject of continu

Alejandro Kievsky

In order to improve the description of the N-d vector analyzing powers Ay and iT11 (the so-called Ay puzzle) a spin-orbit three-body force has been introduced. The L.S term in the NN potential has been modified including a two-parameter three-body function depending on the hyperradius ρ. The modification has been performed in channels where the pair nucleons

Yongseok Oh, Alexander I. Titov, Shin Nan Yang, Toshiyuki Morii

We study the possibility to constrain the hidden strangeness content of the nucleon by means of the polarization observables in phi meson electroproduction. We consider the OZI evading direct knockout mechanism that arises from the non-vanishing s\bar{s} sea quark admixture of the nucleon as well as the background of the dominant diffractive and the one-boso

Il-Tong Cheon

The life-time of $^{133}Cs$ in the first excited state has been measured with the Mössbauer method by placing the absorber, CsCl, between two parallel flat plates and the gamma-ray source, Ba^*TiO_3, in the free space. The result is 9.37 \pm 0.19 ns, which is 49 percent larger than the standard value 6.27 \pm 0.02 ns.

Yuri A. Rylov

It is shown that in the two-dimensional space-time the dynamic system, described by the free Klein-Gordon equation, turns to the dynamic system, described by the free Dirac equation, provided the current and the energy-momentum tensor are redefined in a proper way.

J. Buitrago, Chus Martin

We show that the electromagnetic field tensor and the Lorentz Force are both a natural consequence of the geometric structure of Minkowskian space, being related to infinitesimal boosts and rotations in spacetime. The longstanding issue about the apparent empirical origin of the Lorentz Force is clarified.

J. F. Feinstein, Herbert Kamowitz

In this note we study the endomorphisms of certain Banach algebras of infinitely differentiable functions on compact plane sets, associated with weight sequences M. These algebras were originally studied by Dales, Davie and McClure. In a previous paper this problem was solved in the case of the unit interval for many weights M. Here we investigate the extent

Israel M. Gelfand, Mark I. Graev

We describe a new approach to the notion of general hypergeometric functions

K. Kokhas, A. Suvorov

Let H be the discrete 3-dimensional Heisenberg group with the standard generators x, y, z. The element Delta of the group algebra for H of the form Delta= (x+x^{-1}+y+y^{-1})/4 is called the Laplace operator. This operator can also be defined as transition operator for random walk on the group. The spectrum of Delta in the regular representation of H is the

Evarist Giné, Stanisław Kwapień, Rafał Latała, Joel Zinn

Let X,X_1,X_2,... be independent identically distributed random variables and let h(x,y)=h(y,x) be a measurable function of two variables. It is shown that the bounded law of the iterated logarithm, $\limsup_n (n\log\log n)^{-1}|\sum_{1<= i< j<= n}h(X_i,X_j)|<\infty$ a.s., holds if and only if the following three conditions are satisfied: h is canonical for

A. Boutet de Monvel, A. Khorunzhy

We describe the resolvent approach for the rigorous study of the mescoscopic regime of Hermitian matrix spectra. We present results reflecting the universal behavior of the smoothed density of eigenvalue distribution of large random matrices

Anton Alekseev, Eckhard Meinrenken, Chris Woodward

We prove a localization formula for group-valued equivariant de Rham cohomology of a compact G-manifold. This formula is a non-trivial generalization of the localization formula of Berline-Vergne and Atiyah-Bott for the usual equivariant de Rham cohomology. As an application, we obtain a version of the Duistermaat-Heckman formula for Hamiltonian spaces with

Vik. S. Kulikov, M. Teicher

In this manuscript we prove that if two cuspidal plane curves have equivalent braid monodromy factorizations, then they are smoothly isotopic in the plane. As a consequence of this and the Chisini conjecture, we obtain that if two discriminant curves (or branch curves in other terminology) of generic projections (to the plane) of surfaces of general type imb

A. Sevostyanov

In 1978 Kostant suggested the Whittaker model of the center of the universal enveloping algebra U(g) of a complex simple Lie algebra g. The main result is that the center of U(g) is isomorphic to a commutative subalgebra in U(b), where b is a Borel subalgebra in g. This observation is used in the theory of principal series representations of the correspondin

S. M. Gusein-Zade, I. Luengo, A. Melle-Hernandez

In a previous paper the authors elaborated notions and technique which could be applied to compute such invariants of polynomials as Euler characteristics of fibres and zeta-functions of monodromy transformations associated with a polynomial. Some crucial basic properties of the notions related to the topology of meromorphic germs were not discussed there. T

Konrad Schmuedgen

Let $f$ be a holomorphic function on the strip $\{z\in C: -α<Im z<α\}, α> 0$, belonging to the class $H(α,-α;ε)$ defined below. It is shown that there exist holomorphic functions $w_1$ on $\{z\in C: 0<Im z <2 α\}$ and $w_2$ on $\{z\in C: -2 α<Im z<2 α\}$ such that $w_1$ and $w_2$ have boundary values of modulus one on the real axis and satisfy the relation $

Sergey Yuzvinsky

We give a necessary and sufficient condition on a homogeneous polynomial ideal for its Taylor complex to be exact. Then we give a combinatorial construction of a minimal resolution for ideals satisfying the above condition (in particular for monomial ideals).

J. A. Espichan Carrillo, A. Maia, V. Mostepanenko

The general static solutions of the scalar field equation for the potential $V(ϕ)= -1/2 M^2ϕ^2 + λ/4 ϕ^4$ are determined for a finite domain in $(1+1)$ dimensional space-time. A family of real solutions is described in terms of Jacobi Elliptic Functions. We show that the vacuum-vacuum boundary conditions can be reached by elliptic cn-type solutions in a fini

Matthias Doerrzapf

We analyse the highest weight representations of the N=1 Ramond algebra and show that their structure is richer than previously suggested in the literature. In particular, we show that certain Verma modules over the N=1 Ramond algebra contain degenerate (2-dimensional) singular vector spaces and that in the supersymmetric case they can even contain subsingul

Edwin Langmann, Antti J. Niemi

We employ a heat kernel expansion to derive an effective action that describes four dimensional SU(2) Yang-Mills theory in the infrared limit. Our result supports the proposal that at large distances the theory is approximated by the dynamics of knotted string-like fluxtubes which appear as solitons in the effective theory.

Bihn Zhou, Chuan-Jie Zhu

In this paper, we use only the equation of motion for an interacting system of gravity, dilaton and antisymmetric tensor to study the black brane solutions. By making use of the property of Schwarzian derivative, we obtain the complete solution of this system of equations. For some special values we obtain the well-known BPS brane and black brane solutions.

Matthias Doerrzapf

The construction of Neveu-Schwarz superconformal field theories for any N is given via a superfield formalism. We also review some results and definitions of superconformal manifolds and we generalise contour integration and Taylor expansion to superconformal spaces. For arbitrary N we define (uncharged) primary fields and give their infinitesimal change und

Paul Langacker

Aspects of theoretical electroweak physics are summarized, including the status of electroweak radiative corrections, the hadronic contribution to the running of alpha, global fits to precision data and their implication for testing the standard model and constraining new physics, and electroweak baryogenesis.

M. Consoli, P. M. Stevenson

We discuss the phase transition in 3+1 dimensional lambda Phi^4 theory from a very physical perspective. The particles of the symmetric phase (`phions&#39;) interact via a hard-core repulsion and an induced, long-range -1/r^3 attraction. If the phion mass is sufficiently small, the lowest-energy state is not the `empty&#39; state with no phions, but is a sta

Stefano Catani, Michael H. Seymour

We calculate the second-order QCD corrections to the forward-backward asymmetry in $e^+e^-$ annihilation. Using the quark axis definition, we do not agree with either existing calculation, but the difference relative to one of them is small and understood. In particular, we point out that the forward-backward asymmetry of massive quarks is enhanced by logari

Marco Aurelio Diaz

We review some properties of Bilinear R-Parity Violating models: simple extensions of the Minimal Supersymmetric Standard Model motivated by spontaneous breaking of R-Parity. We concentrate on the relaxation of the bounds on the charged Higgs mass imposed by the measurement of B(b -> s gamma), the effect on the mass of the lightest neutral Higgs boson, the r

J. Bellandi, J. R. Fleitas

We calculate the inelastic proton-air cross section by means of the Glauber model. As input, we use accelerator experimental data on the total proton-proton cross section and compare with cosmic ray experimental data and Monte Carlo simulations. Contribution to the 26th International Cosmic Ray Conference, Salt Lake City, Utah. HE 1.3.13. August, 1999.

J. Bellandi, J. R. Fleitas, J. Dias de Deus

We present in this paper a calculation of the hadronic flux in the atmosphere. Using an iterative leading particle model and the Glauber model, we relate the moment of the leading particle distribution in nucleon-air collisions with the respective one in nucleon-proton collisions. In this way, we obtain a description of the nucleonic and hadronic fluxes in t

Pran Nath, Youichi Yamada, Masahiro Yamaguchi

It is shown that the nature of compactification of extra dimensions in theories of large radius compactification can be explored in several processes at the Large Hadron Collider (LHC). Specifically it is shown that the characteristics of the Kaluza-Klein (KK) excitations encode information on the nature of compactification, i.e., on the number of compactifi

A. W. Thomas, D. B. Leinweber, D. H. Lu

We explore the chiral aspects of extrapolation of observables calculated within lattice QCD, using the nucleon magnetic moments as an example. Our analysis shows that the biggest effects of chiral dynamics occur for quark masses corresponding to a pion mass below 600 MeV. In this limited range chiral perturbation theory is not rapidly convergent, but we can

G. Borisov, F. Richard

Assuming a SM or MSSM scenario, one expects a light Higgs boson which could be studied in great detail with a LC operating at \sqrt s>m_h+m_Z. In the TESLA scenario, with 500 fb^-1 accumulated at \sqrt s = 350 GeV, about 10^5 hZ events could be produced through the Higgstrahlung process. At a future LC with a \sim 1 cm beam-pipe radius and a thin Si detector

H. H. Asatryan, H. M. Asatrian, D. Wyler

We calculate the next-to-leading corrections to the branching ratio of exclusive $B\to K^* γ$ decay. The renormalization scale dependence is reduced compared to the leading logarithmic result but there remains a dependence on a cutoff parameter of the hadronic model. The calculated corrections increase the predicted branching ratio by about 10%, but it remai

C. A. Dominguez, K. Schilcher

A set of well known chiral sum rules, expected to be valid in QCD, is confronted with experimental data on the vector and axial-vector hadronic spectral functions, obtained from tau-lepton decay by the ALEPH collaboration. The Das-Mathur-Okubo sum rule, the first and second Weinberg sum rules, and the electromagnetic pion mass difference sum rule are not wel

Xiangdong Ji, Jonathan Osborne

The Drell-Hearn-Gerasimov and Bjorken sum rules are special examples of dispersive sum rules for the spin-dependent structure function G_1(ν, Q^2) at Q^2=0 and \infty. We generalize these sum rules through studying the virtual-photon Compton amplitudes S_1(ν, Q^2) and S_2(ν,Q^2). At small Q^2, we calculate the Compton amplitudes at leading-order in chiral pe

P. L. McGaughey, J. M. Moss, J. C. Peng

We review the production of high-mass lepton pairs in fixed-target experiments, including both Drell-Yan (DY) and heavy quarkonium (J/Psi and Upsilons) production.

Robert G. Edwards, Urs M. Heller, Rajamani Narayanan

The Overlap-Dirac operator provides a lattice regularization of massless vector gauge theories with an exact chiral symmetry. Practical implementations of this operator and recent results in quenched QCD using this Overlap-Dirac operator are reviewed.

Rajan Gupta

In this introductory article a brief description of Quantum Field Theories (QFT) is presented with emphasis on the distinction between strongly and weakly coupled theories. A case is made for using numerical simulations to solve QCD, the regnant theory describing the interactions between quarks and gluons. I present an overview of what these calculations inv

A. V. Sidorov

The isoscalar structure functions $xF_3$ and $F_2$ are measured as functions of $x$ averaged over all $Q^2$ permissible for the range of 6 to 28 GeV of incident neutrino (anti-neutrino) energy at the IHEP-JINR Neutrino Detector. The QCD analysis of $xF_3$ structure function provides $Λ_{\bar{MS}}^{(4)} = (411 \pm 200)$ MeV under the assumption of QCD validit

Luiz Americo de Carvalho, Carola Dobrigkeit

We explore the feasibility of estimating primary cosmic ray composition at ultra high energies from the sum of muon, electron and photon densities and the depth of maximum of extensive air showers detected by the Auger Observatory. From the information of the Fluorescence ($X_{max}$) and water Cerenkov detectors ($ρ(1000)$) we infere the most probable type o

The Soudan 2 Collaboration, J. H. Cobb et al

A shadow of the moon, with a statistical significance of 5 sigma, has been observed in the underground muon flux at a depth of 2090 mwe using the Soudan 2 detector. The angular resolution of the detector is well described by a Gaussian with a sigma of less than 0.3 degrees. The position of the shadow confirms that the alignment of the detector is known to be

Gaurav Khanna, John Baker, Reinaldo Gleiser, Pablo Laguna

Using several approximations, we calculate an estimate of the gravitational radiation emitted when two equal mass black holes coalesce at the end of their binary inspiral. We find that about 1% of the mass energy of the pair will emerge as gravitational waves during the final ringdown and a negligible fraction of the angular momentum will be radiated.

P. Teyssandier

We define a general class of superenergy tensors of even rank 2(n+1) for a real massive scalar field propagating in Minkowski spacetime. In the case where n=1, we establish that this class is a two-parameter family, which reduces to a unique tensor W(up to a constant factor) when the complete symmetry on the four indices is required. We show that the superen

Peter Diener, Nina Jansen, Alexei Khokhlov, Igor Novikov

The initial data for black hole collisions is constructed using a conformal-imaging approach and a new adaptive mesh refinement technique, a fully threaded tree (FTT). We developed a second-order accurate approach to the solution of the constraint equations on a non-uniformly refined high resolution Cartesian mesh including second-order accurate treatment of

Maciej Przanowski, Sebastian Formanski, Francisco J. Turrubiates

An example of a sequence of the sl(N;C) chiral fields, for N$\geq 2$, tending to the complex heavenly metric (nonlinear graviton) of the type [4]x[-] when N --> infinity is given.

Gaspare Carbone, Mauro Carfora, Annalisa Marzuoli

The search for classical or quantum combinatorial invariants of compact n-dimensional manifolds (n=3,4) plays a key role both in topological field theories and in lattice quantum gravity. We present here a generalization of the partition function proposed by Ponzano and Regge to the case of a compact 3-dimensional simplicial pair $(M^3, \partial M^3)$. The r

M. C. Bento, O. Bertolami

We study the possibility that the vacuum energy density of scalar and internal-space gauge fields arising from the process of dimensional reduction of higher dimensional gravity theories plays the role of quintessence. We show that, for the multidimensional Einstein-Yang-Mills system compactified on a $R \times S^3 \times S^d$ topology, there are classically

Danilo Babusci, Massimo Giovannini

There are no reasons why the energy spectra of the relic gravitons, amplified by the pumping action of the background geometry, should not increase at high frequencies. A typical example of this behavior are quintessential inflationary models where the slopes of the energy spectra can be either blue or mildly violet. In comparing the predictions of scenarios

Kagan Tumer, Joydeep Ghosh

Integrating the outputs of multiple classifiers via combiners or meta-learners has led to substantial improvements in several difficult pattern recognition problems. In the typical setting investigated till now, each classifier is trained on data taken or resampled from a common data set, or (almost) randomly selected subsets thereof, and thus experiences si

Kagan Tumer, Joydeep Ghosh

Several researchers have experimentally shown that substantial improvements can be obtained in difficult pattern recognition problems by combining or integrating the outputs of multiple classifiers. This chapter provides an analytical framework to quantify the improvements in classification results due to combining. The results apply to both linear combiners

Kagan Tumer, Nirmala Ramanujam, Joydeep Ghosh, Rebecca Richards-Kortum

The mortality related to cervical cancer can be substantially reduced through early detection and treatment. However, current detection techniques, such as Pap smear and colposcopy, fail to achieve a concurrently high sensitivity and specificity. In vivo fluorescence spectroscopy is a technique which quickly, non-invasively and quantitatively probes the bioc

D. Caroppo, M. Mannarelli, G. Nardulli, S. Stramaglia

Time evolution of diluted neural networks with a nonmonotonic transfer function is analitically described by flow equations for macroscopic variables. The macroscopic dynamics shows a rich variety of behaviours: fixed-point, periodicity and chaos. We examine in detail the structure of the strange attractor and in particular we study the main features of the

H. Blas, B. M. Pimentel, J. L. Tomazelli

In this work we study the behavior of relativistic ideal Bose and Fermi gases in two space dimensions. Making use of polylogarithm functions we derive a closed and unified expression for their densities. It is shown that both type of gases are essentially inequivalent, and only in the non-relativistic limit the spinless and equal mass Bose and Fermi gases ar