August 1998 arXiv papers — page 5

Rong-Gen Cai, Kwang-Sup Soh

We investigate the topological black holes in a special class of Lovelock gravity. In the odd dimensions, the action is the Chern-Simons form for the anti-de Sitter group. In the even dimensions, it is the Euler density constructed with the Lorentz part of the anti-de Sitter curvature tensor. The Lovelock coefficients are reduced to two independent parameter

Marco A. Diaz, E. Torrente-Lujan, J. W. F. Valle

The experimental measurement of $B(b \to sγ)$ imposes important constraints on the charged Higgs boson mass in the MSSM. If squarks are in the few TeV range, the charged Higgs boson mass in the MSSM must satisfy $m_{H^{\pm}} \gsim 440$ GeV. For lighter squarks, then light charged Higgs bosons can be reconciled with $B(b \to sγ)$ only if there is also a light

Junji Hisano, Mihoko M. Nojiri, Yasuhiro Shimizu, Minoru Tanaka

The Super-Kamiokande atmospheric neutrino data suggest existence of the large lepton-flavor violating (LFV) interaction in the higher energy scale. If the minimal supersymmetric standard model is extended to have right-handed neutrinos, the left-handed sleptons in the second and third generations are expected to have the LFV masses in the minimal supergravit

Luigi Foschini

The passage of particles through matter is one of the principal ways to investigate nature. In this article, we would like to outline the most important stages in the development of the theory about the stopping power.

Mauro Fortunato, Gershon Kurizki, Wolfgang P. Schleich

We propose a scheme which can effectively restore fixed points in the quantum dynamics of repeated Jaynes-Cummings interactions followed by atomic state measurements, when the interaction times fluctuate randomly. It is based on selection of superposed atomic states whose phase correlations tend to suppress the phase fluctuations of each separate state. One

Andrzej Roslanowski, Saharon Shelah

The present paper addresses the problem of attainment of the supremums in various equivalent definitions of hereditary density hd and hereditary Lindelof degree hL of Boolean algebras. We partially answer two problems of J. Donald Monk (Problems 50 and 54 in his book "Cardinal Invariants on Boolean Algebras), showing consistency of different attainment b

E. Ribeiro, R. Jaeggi, T. Heinzel, K. Ensslin

A metal-insulator transition in two-dimensional electron gases at B=0 is found in Ga(Al)As heterostructures, where a high density of self-assembled InAs quantum dots is incorporated just 3 nm below the heterointerface. The transition occurs at resistances around h/e^2 and critical carrier densities of 1.2 10^11cm^-2. Effects of electron-electron interactions

Daijiro Suematsu

Vacuum structure and related phenomenological features are investigated in $μ$-problem solvable supersymmetric extra U(1) models. We present a framework for the analysis of their vacuum structure taking account of an abelian gauge kinetic term mixing, which can potentially modify a scalar potential and $Z^0$ gauge interactions. Applying this to data of the p

G. P. Pronko, Yu. G. Stroganov

We analyse the famous Baxter's $T-Q$ equations for $XXX$ ($XXZ$) spin chain and show that apart from its usual polynomial (trigonometric) solution, which provides the solution of Bethe-Ansatz equations, there exists also the second solution which should corresponds to Bethe-Ansatz beyond $N/2$. This second solution of Baxter's equation plays essentia

Ji-Ho Jang, Jae Sik Lee

We study CP violating B decays in the minimal supersymmetric standard model with R-parity violation. We estimate how much R-parity violation modifies the SM predictions for CP asymmetries in B decays within the present bounds. The effects of R-parity- and lepton-number-violating couplings on the ratio of the decay amplitude due to R-parity violation to that

M. alimohammadi, A. Shariati

Using the Einstein-Cartan-Dirac theory, we study the effect of torsion on neutrino oscillation. We see that torsion cannot induce neutrino oscillation, but affects it whenever oscillation exists for other reasons. We show that the torsion effect on neutrino oscillation is as important as the neutrino mass effect, whenever the ratio of neutrino number density

Bruce A. Bassett, David I. Kaiser, Roy Maartens

General relativistic effects in the form of metric perturbations are usually neglected in the preheating era that follows inflation. We argue that in realistic multi-field models these effects are in fact crucial, and the fully coupled system of metric and quantum field fluctuations needs to be considered. Metric perturbations are resonantly amplified, break

Karl Glazebrook, Chris Blake, Frossie Economou, Simon Lilly

We report the results of J-band infrared spectroscopy of a sample of 13 z=1 field galaxies drawn from the Canada-France Redshift Survey, targeting galaxies whose redshifts place the rest frame H-alpha line emission from HII regions in between the bright night sky OH lines. As a result we detect emission down to a flux limit of ~10^{-16} ergs cm^{-2} s^{-1} c

V. M. Tkachuk

Using supersymmetric quantum mechanics we develop a new method for constructing quasi-exactly solvable (QES) potentials with two known eigenstates. This method is extended for constructing conditionally-exactly solvable potentials (CES). The considered QES potentials at certain values of parameters become exactly solvable and can be treated as CES ones.

Mauro Fortunato, Gershon Kurizki, Wolfgang P. Schleich

We propose a method which can effectively stabilize fixed points in the classical and quantum dynamics of a phase-sensitive chaotic system with feedback. It is based on feeding back a selected quantum sub-ensemble whose phase and amplitude stabilize the otherwise chaotic dynamics. Although the method is rather general, we apply it to realizations of the inhe

S. S. Sannikov, A. A. Stanislavsky

The purpose of this paper is to present the mathematical techniques of a new quantum scheme using a dual pair of reflexive topological vector spaces in terms of the non-Hermitian form. The scheme is shown to be a generalization of the well-known unitary quantum theory and to describe jointly quantum objects and physical vacuum.

S. S. Sannikov, A. A. Stanislavsky

The problem of ultraviolet divergences is analysed in the quantum field theory. It was found that it has common roots with the problem of cosmological singularity. In the context of fibre bundles the second quantization method is represented as a procedure of the quantization for vector bundle cross-section. It is shown to be quite a different quantization w

P. L. Colestock, L. K. Spentzouris, S. I. Tzenov

Nonlinear waves have been observed in synchrotrons for years but have received little attention in the literature. While pathological, these phenomena are worth studying on at least two accounts. First, the formation of solitary waves may lead to droplet formation that causes significant beam halo to develop. Secondly, a variety of nonlinear processes are li

Luigi Foschini

During the 80's, some experiments and the repetitions of old ones, lead to the hypothesis of a fifth force. Nevertheless, a more accurate research was not able to confirm this hypothesis. This article wants to go over again the most important steps of the event.

G. Ramalho, A. Arriaga, M. T. Peña

In this work improvements to the application of the Gross equation to nuclear systems are tested. In particular we evaluate the two pion exchange diagrams, including the crossed-box diagram, using models developed within the spectator-on-mass-shell covariant formalism. We found that the form factors used in these models induce spurious contributions that vio

S. Misicu, D. Protopopescu

We investigate the influence of the nuclear deformation on the decay rates of some cluster emission processes. The interaction between the daughter and the cluster is given by a double folding potential including quadrupole and hexadecupole deformed densities of both fragments. The nuclear part of the nucleus-nucleus interaction is density dependent and at s

P. Lubinski, J. Jastrzebski, A. Trzcinska, W. Kurcewicz

Thirteen targets with mass numbers from 58 to 238 were irradiated with the antiproton beam from the Low Energy Antiproton Ring facility at CERN leading to the formation of antiprotonic atoms of these heavy elements. The antiproton capture at the end of an atomic cascade results in the production of more or less excited residual nuclei. The targets were selec

Martin R. Zirnbauer

Gaussian random matrix ensembles defined over the tangent spaces of the large families of Cartan's symmetric spaces are considered. Such ensembles play a central role in mesoscopic physics since they describe the universal ergodic limit of disordered and chaotic single particle systems. The generating function for the spectral correlations of each ensemb

Martin Markl, Steve Shnider

The main results of our paper deal with the lifting problem for multilinear differential operators between complexes of horizontal de Rham forms on the infinite jet bundle. We answer the question when does an n-multilinear differential operator from the space of (N,0)-forms (where N is the dimension of the base) to the space of (N-s,0)-forms allow an n-multi

E. D'Hoker, D. H. Phong

The classical order parameters for the $\N=2$ supersymmetric SU(N) gauge theory with matter in the adjoint representation are exhibited explicitly as conservation laws for the elliptic Calogero-Moser system. Central to the construction are certain elliptic function identities, which arise from considering Feynman diagrams in a theory of free fermions with tw

L. Driesen, M. Stingl

We study the self-consistency problem of the generalized Feynman rule (nonperturbatively modified vertex of zeroth perturbative order) for the 4-gluon vertex function in the framework of an extended perturbation scheme accounting for non-analytic coupling dependence through the Lambda scale. Tensorial structure is restricted to a minimal dynamically closed b

L. Driesen, J. Fromm, J. Kuhrs, M. Stingl

In the framework of a generalized iterative scheme introduced previously to account for the non-analytic coupling dependence associated with the renormalization-group invariant mass scale Lambda, we establish the self-consistency equations of the extended Feynman rules (Lambda-modified vertices of zeroth perturbative order) for the three-gluon vertex, the tw

Norbert Duechting, Sergei V. Shabanov, Thomas Strobl

A global extension of the Batalin-Marnelius proposal for a BRST inner product to gauge theories with topologically nontrivial gauge orbits is discussed. It is shown that their (appropriately adapted) method is applicable to a large class of mechanical models with a semisimple gauge group in the adjoint and fundamental representation. This includes cases wher

Yi-Xin Chen, Xu-Dong Luo, Ke Wu

We study two-dimensional classically integrable field theory with independent boundary condition on each end, and obtain three possible generating functions for integrals of motion when this model is an ultralocal one. Classically integrable boundary condition can be found in solving boundary $K_{\pm}$ equations. In quantum case, we also find that unitarity

Dan Radu Grigore

We generalise a result of Aste and Scharf saying that, under some reasonable assumptions, consistent with renormalisation theory, the non-Abelian gauge theories describes the only possibility of coupling the gluons. The proof is done using Epstein-Glaser approach to renormalisation theory.

R. D. Peccei

In these lectures I examine some of the principal issues in cosmology from a particle physics point of view. I begin with nucleosynthesis and show how the primordial abundance of the light elements can help fix the number of (light) neutrino species and determine the ratio $η$ of baryons to photon in the universe now. The value of $η$ obtained highlights two

C. S. Lam

Energy dependence of $γ^*p$ total cross section is considered. It is known from the HERA data that the cross section grows with energy, and the rate of growth is an increasing function of the virtuality $Q^2$ of the photon $γ^*$. This dependence can be explained in a simple and generic way by the Froissart bound. To implement this mechanism quantitatively a

E. Shuryak

An overview of some issues discussed is given, including the following ones: (i) the mechanism of confinement, (ii) the structure of the string, (iii) non-perturbative glue in vacuum and hadrons, and (v) quark-hadron duality. In doing so I try to indicate issues important for JLab. Finally I discuss another issue debated during this conference, namely (vi) w

Deirdre Black, Amir H. Fariborz, Francesco Sannino, Joseph Schechter

We investigate the "family" relationship of a possible scalar nonet composed of the a_0(980), the f_0(980) and the σand κtype states found in recent treatments of ππand πK scattering. We work in the effective Lagrangian framework, starting from terms which yield "ideal mixing" according to Okubo's original formulation. It is noted that th

Yu. F. Pirogov, O. V. Zenin

The two-loop renormalization group global profile of the Standard Model (SM) in its full parameter space is investigated. Restrictions on the Higgs boson mass as a function of a cutoff scale are obtained from the stability of the electroweak vacuum and from the perturbative validity both in the Higgs and Yukawa sectors. The cutoff equal to the Planck scale r

B. Dion, L. Marleau, G. Simon

We perform a systematic analysis of scalar and vector leptoquark pair production at the Fermilab Tevatron and at the CERN LHC. We evaluate signal expectations and background levels for the processes pp (p ppar) -> 2 jets + e^{+} + e^{-} and 2 jets + e + missing p_T. The Monte Carlo event generator ISAJET is used to simulate the experimental conditions at the

Salvatore Mele

The LEP investigation of the Bd and Bs oscillations and of the Cabibbo-Kobayashi-Maskawa matrix element Vub improve the constraints on the other elements of this matrix. From a fit to the experimental data and the theory calculations it is possible to determine the vertex of the unitarity triangle as: rho = 0.155 -0.105 +0.115 eta = 0.383 -0.060 +0.063. The

Juerg Schacher

The DIRAC experiment, a magnetic double arm spectrometer, aims to measure the $π^+π^-$ atom lifetime with 10% precision, using the high intensity 24 GeV/c proton beam of the CERN Proton Synchrotron. Since the value of this lifetime of order $10^{-15}$~s is dictated by strong interaction at low energy, a precise measurement of this quantity enables to study c

C. Giunti

Several possible statistical interpretations of the null result of the KARMEN 2 neutrino oscillation experiment are discussed with the aim of clarifying the implications of the fact that KARMEN 2 did not observe any of the expected background events. The formalism that allows to take into account the error of the expected mean background in a Poisson process

Alex Krasnitz, Raju Venugopalan

We discuss real time simulations of high energy nuclear collisions in a classical effective theory of QCD at small x. At high transverse momenta, our results match the lowest order predictions of pQCD based mini-jet calculations. We discuss novel non-perturbative behaviour of the small x modes seen at small transverse momenta.

F. Araki, M. Musakhanov, H. Toki

The systematic investigations of the role of the virtual charm axial currents in the decay of $B$-mesons to $η'$ $K$ and the spin structure of the nucleon are performed. We reduce the divergence of the virtual charm axial current to a specific gluon operator. Since this operator receives the main contribution from topologically nontrivial components of t

P. H. Damgaard

Random matrix theory and chiral Lagrangians offer a convenient tool for the exact calculation of microscopic spectral correlators of the Dirac operator in a well-defined finite-volume scaling regime.

S. Ejiri, Y. Iwasaki, K. Kanaya

We propose a new non-perturbative method to compute derivatives of gauge coupling constants with respect to anisotropic lattice spacings (anisotropy coefficients). Our method is based on a precise measurement of the finite temperature deconfining transition curve in the lattice coupling parameter space extended to anisotropic lattices by applying the spectra

D. B. Leinweber, J. I. Skullerud, A. G. Williams

The gluon propagator in the Landau gauge is calculated in quenched QCD on a large lattice (32^3x64) at beta=6.0. In order to assess finite volume and finite lattice spacing artefacts, we also calculate the propagator on a smaller volume for two different values of the lattice spacing. New structure seen in the infrared region survives conservative cuts to th

Yamaguchi Azusa

An Algorithm is proposed for the simulation of pure SU(N) lattice gauge theories based on Genetic Algorithms(GAs). Main difference between GAs and Metropolis methods(MPs) is that GAs treat a population of points at once, while MPs treat only one point in the searching space. This provides GAs with information about the assortment as well as the fitness of th

The OPAL Collaboration, K. Ackerstaff et al

Searches for a scalar top quark and a scalar bottom quark have been performed using a total data sample of 56.8 pb-1 at a centre-of-mass energy of 183 GeV collected with the OPAL detector at LEP. No candidate events were observed. Combining this result with those obtained at lower centre-of-mass energies, the 95% C.L. lower limit on the scalar top quark mass

J. Bicak, A. Pravdova

Symmetries compatible with asymptotic flatness and admitting gravitational and electromagnetic radiation are studied by using the Bondi-Sachs-van der Burg formalism. It is shown that in axially symmetric electrovacuum spacetimes in which at least locally a smooth null infinity in the sense of Penrose exists, the only second allowable symmetry is either the t

D. V. Ahluwalia

The recently introduced mechanism of flavor-oscillation clocks has been used to emphasize observability of constant gravitational potentials and thereby to question completeness of the theory of general relativity. An inequality has been derived to experimentally test the thesis presented.

Jon Crowcroft, Philippe Oechslin

In this document we study the application of weighted proportional fairness to data flows in the Internet. We let the users set the weights of their connections in order to maximise the utility they get from the network. When combined with a pricing scheme where connections are billed by weight and time, such a system is known to maximise the total utility o

R. Zeyher, A. Greco

The feasibility of a perturbation expansion for Green's functions of the t-J model directly in terms of X-operators is demonstrated using the Baym- Kadanoff functional method. As an application we derive explicit expressions for the kernel of the linearized equation for the superconducting order parameter in leading order of a 1/N expansion. The lineariz

S. Sanvito, C. J. Lambert, J. H. Jefferson, A. M. Bratkovsky

A novel, general Green's function technique for elastic spin-dependent transport calculations is presented, which (i) scales linearly with system size and (ii) allows straightforward application to general tight-binding Hamiltonians (spd in the present work). The method is applied to studies of conductance and giant magnetoresistance (GMR) of magnetic mu

Seung Pyo Lee, Myung-Hoon Chung, Chul Koo Kim, Kyun Nahm

We study the fractional populations in chromosome inherited diseases. The governing equations for the fractional populations are found and solved in the presence of mutation and selection. The physical fixed points obtained are used to discuss the cases of color blindness and hemophilia.

Zs. Szabo, Zs. Gulacsi

Superconducting phase diagram of the extended Hubbard model supplemented with interaction and hopping terms exceeding nearest neighbour distance in range is analysed systematically at different band-filling and temperature values in a mean-field approximation. The obtained results clearly underline the importance of next-nearest neighbour terms in developing

Pierre-Antoine Rey, Michel Droz, Jaroslaw Piasecki

We consider a one-dimensional model consisting of an assembly of two-velocity particles moving freely between collisions. When two particles meet, they instantaneously annihilate each other and disappear from the system. Moreover each moving particle can spontaneously generate an offspring having the same velocity as its mother with probability 1-q. This mod

A. A. Fraerman, S. A. Gusev, L. A. Mazo, I. M. Nefedov

The work is devoted to investigation of the collective behavior of the regular rectangular lattices of the NiFe nanoparticles caused by the dipole-dipole interaction between them. The samples was prepared by the method of the electron lithography and consist of about 100000 particles of approximately 50 nm size. The magnetization curves were investigated by

Yong-Jihn Kim

We point out that the existing experimental data of most manganese oxides show the {\sl frustrated} p-wave superconducting condensation in the ferromagnetic phase in the sense that the superconducting coherence is not long enough to cover the whole system. The superconducting state is similar to the $A_{1}$ state in superfluid He-3. The sharp drop of resisti

Yukio Hirano, Yoshiyuki Ono

Dynamical process of the formation of a soliton pair from a photogenerated electron-hole pair in polyacetylene is studied numerically by adopting the SSH Hamiltonian. A weak local disorder is introduced in order to trigger the formation. Starting from an initial configuration with an electron at the bottom of the conduction band and a hole at the top of the

Peter Freche, Martin Janssen, Rainer Merkt

Scattering theoretical network models for general coherent wave mechanical systems with quenched disorder are investigated. We focus on universality classes for two dimensional systems with no preferred orientation: Systems of spinless waves undergoing scattering events with broken or unbroken time reversal symmetry and systems of spin 1/2 waves with time re

Sven Hartrumpf

Multiple default inheritance formalisms for lexicons have attracted much interest in recent years. I propose a new efficient method to access such lexicons. After showing two basic strategies for lookup in inheritance lexicons, a compromise is developed which combines to a large degree (from a practical point of view) the advantages of both strategies and av

Norbert Broeker

This paper proposes decoupling the dependency tree from word order, such that surface ordering is not determined by traversing the dependency tree. We develop the notion of a \emph{word order domain structure}, which is linked but structurally dissimilar to the syntactic dependency tree. The proposal results in a lexicalized, declarative, and formally precis

Philippe Marcq, Antoine Naert

Experimental data from a turbulent jet flow is analysed in terms of an additive, continuous stochastic process where the usual time variable is replaced by the scale. We show that the energy transfer through scales is well described by a linear Langevin equation, and discuss the statistical properties of the corresponding random force in detail. We find that

C A Jackson, J V Wall

Extragalactic radio sources are a unique cosmological probe in that they trace large-scale structure on scales inaccessible to other wavelengths. However as radio survey data is inherently 2D, the redshift distribution, N(z), is necessary to derive spatial information. To obtain this distribution either we measure thousands of radio source redshifts to direc

Amri Wandel

We derive a theoretical relation between $R_{BLR}$, the size of the broad-emission-line region of active galactic nuclei, and the observed soft X-ray luminosity and spectrum. We show that in addition to the well known $R_{BLR}\sim L^{1/2}$ scaling, $R_{BLR}$ should depend also on the spectral shape and derive the expected relation between $R_{BLR}$ and the X

Benjamin D. Wandelt, Eric Hivon, Krzysztof M. Gorski

As the era of high precision cosmology approaches, the empirically determined power spectrum of the microwave background anisotropy, $C_l$, will provide a crucial test for cosmological theories. We present a unified semi-analytic framework for the study of the statistical properties of the $C_l$ coefficients computed from the results of balloon, ground based

Mario Livio, Massimo Stiavelli

We discuss how laboratory experiments can be used to place constraints on possible variations of the fine structure constant alpha in the observationally relevant redshift interval z ~= 0 - 5, within a rather general theoretical framework. We find a worst case upper limit for Delta alpha / alpha of 8 x 10^-6 for z <= 5 and Delta alpha / alpha of 0.9 x 10^-6

Noam Soker

We examine the possibility of detecting signatures of surviving Uranus-Neptune-like planets inside planetary nebulae. Planets that are not too close to the stars, orbital separation larger than about 5 AU, are likely to survive the entire evolution of the star. As the star turns into a planetary nebula, it has a fast wind and a strong ionizing radiation. The

Noam Soker

I propose a mechanism for axisymmetrical mass loss on the asymptotic giant branch, that may account for the axially symmetric structure of elliptical planetary nebulae. The proposed model operates for slowly rotating AGB stars, having angular velocities of 0.0001 the Keplerian velocity. Such angular velocities could be gained from a planet companion of mass

Frank J. Masci

If the background universe is observed through a significant amount of diffusely distributed foreground dust, then studies at optical wavelengths may be severely biased. Previous studies investigating effects of foreground dust on background sources assumed the dust to be ``compactly&#39;&#39; distributed, ie. on scales comparable to the visible extent of no

D. Elizondo, G. Yepes, R. Kates, V. Müller

Using 3D hydrodynamical simulations of galaxy formation with supernova feedback and a multiphase medium, we derive theoretical relations analogous to the observed Tully-Fisher (TF) relations in various photometric bands. This paper examines the influence of self-regulation mechanisms including supernova feedback on galaxy luminosities and the TF relation in

Frank J. Masci, Michael J. Drinkwater, Rachel L. Webster

The Parkes Half-Jansky Flat Spectrum Sample contains a large number of sources with unusually red optical-to-near-infrared continua. If this is to be interpreted as extinction by dust in the line-of-sight, then associated material might also give rise to absorption in the soft X-ray regime. This hypothesis is tested using broadband (0.1-2.4 keV) data from th

Y. -Z. Qian, P. Vogel, G. J. Wasserburg

Using the data of Richter et al. (1998) on Te isotopes in diamond grains from a meteorite, we derive bounds on the neutrino fluence and the decay timescale of the neutrino flux relevant for the supernova r-process. Our new bound on the neutrino fluence F after freeze-out of the r-process peak at mass number A = 130 is more stringent than the previous bound F

Ehud Cohen, Tsvi Piran

We use general arguments to show that a continuously powered radiative blast wave can behave self similarly if the energy injection and radiation mechanisms are self similar. In that case, the power-law indices of the blast wave evolution are set by only one of the two constituent physical mechanisms. If the luminosity of the energy source drops fast enough,

T. Treu, M. Stiavelli, A. R. Walker, R. E. Williams

We report the serendipitous discovery of an extremely red object in the Hubble Deep Field South (HDFS) Test NICMOS (Near Infrared Camera and Multi Object Spectrograph) field of view. The object is resolved in the NICMOS image and has a light profile very well described by an r^{1/4} law with effective radius r_e=0.&#34;20+-0.&#34;05 and H_{AB}=21.7+-0.1 magn

Mariano Mendez, Michiel van der Klis, Jan van Paradijs

We have analyzed data obtained during two observations with the Rossi X-ray Timing Explorer on January 5 and 8, 1997, of the low-mass X-ray binary (LMXB) and atoll source 4U 1636-53. We measure the frequency separation of the two simultaneous kilohertz quasi-periodic oscillations (kHz QPOs) in this source to be 253.7 +/- 4.7 and 246.4 +/- 5.4 Hz, respectivel

A. Raga, A. Noriega-Crespo

Variable ejection velocity jet models can qualitatively explain the appearance of successive working surfaces in Herbig-Haro (HH) jets. This paper presents an attempt to explore which features of the HH-34 jet can indeed be reproduced by such a model. From previously published data on this object, we find evidence for the existence of a 3-mode ejection veloc

A. Muecke, J. P. Rachen, R. Engel, R. J. Protheroe

We discuss the first applications of our newly developed Monte Carlo event generator SOPHIA to multiparticle photoproduction of relativistic protons with thermal and power law radiation fields. The measured total cross section is reproduced in terms of excitation and decay of baryon resonances, direct pion production, diffractive scattering, and non-diffract

Andrei Gruzinov, Eliot Quataert

We calculate the proton distribution function due to heating by subsonic (Alfvenic) turbulence in a weakly magnetized collisionless plasma. The distribution function is nonthermal. For non-relativistic energies, it is an exponential of the magnitude of the proton velocity. For ultra-relativistic energies, it can be characterized as a power law with a momentu

Jordi Miralda-Escude

Gamma-ray bursts are now known to be a cosmological population of objects, which are often accompanied by X-ray and optical afterglows. The total energy emitted in the afterglow can be similar to the energy radiated in the gamma-ray burst itself. If a galaxy containing a large column density of dust is near the line of sight to a gamma-ray burst, small-angle

Ofer Aharony, Micha Berkooz, David Kutasov, Nathan Seiberg

We argue that vacua of string theory which asymptote at weak coupling to linear dilaton backgrounds are holographic. The full string theory in such vacua is ``dual&#39;&#39; to a theory without gravity in fewer dimensions. The dual theory is generically not a local quantum field theory. Excitations of the string vacuum, which can be studied in the weak coupl

J. Xu, A. P. S. Crotts

High resolution (10 km/s) [N II] echelle spectra, sampled every 13 arcsec in a 6 arcmin by 6 arcmin region around SN1987A were obtained on the CTIO 4m telescope. The map shows a complicated velocity structure consistent with that reported previously for the interstellar medium. Three components, heliocentric velocity V_hel=265, 277 and 285 km/s are identifie

Rafael Ferraro, Daniel M. Sforza

A generally covariant system can be deparametrized by means of an ``extrinsic&#39;&#39; time, provided that the metric has a conformal ``temporal&#39;&#39; Killing vector and the potential exhibits a suitable behavior with respect to it. The quantization of the system is performed by giving the well ordered constraint operators which satisfy the algebra. The

Alain Rochefort, Dennis R. Salahub, Phaedon Avouris

We calculated the effects of structural distortions on the electronic structure of carbon nanotubes. The key modification of the electronic structure brought about by bending a nanotube involves an increased mixing of $σ$ and $π$-states. This mixing leads to an enhanced density-of-states in the valence band near the Fermi energy region. While in a straight t

John J. Cowan, B. Pfeiffer, K. -L. Kratz, F. -K. Thielemann

Rapid neutron-capture (i.e., r-process) nucleosynthesis calculations, employing internally consistent and physically realistic nuclear physics input (QRPA beta-decay rates and the ETFSI-Q nuclear mass model), have been made. These calculations are compared with ground-based and HST observations of neutron-capture elements in the metal poor halo stars CS 2289

D. Bailin, G. V. Kraniotis, A. Love

Cosmological inflation is studied in the case where the inflaton is the overall modulus $T$ for an orbifold. General forms of the (non-perturbative) superpotential are considered to ensure that $G=K+{\rm ln}|W|^2$ is modular invariant. We find generically that these models do not produce a potential flat enough for slow roll to a supersymmetric minimum, alth

F. del Aguila, J. A. Aguilar-Saavedra, R. Miquel

The extension of the Standard Model with exotic quark singlets and doublets introduces large flavor changing neutral couplings between ordinary fermions. We derive inequalities which translate the precise determination of the diagonal Z couplings, in particular at LEP, into stringent bounds on the off-diagonal ones. The resulting limits can be saturated in m

Jochen Weller, Richard A. Battye, Andreas Albrecht

We investigate the possible effects of reionization by active sources on the cosmic microwave background. We concentrate on the sources themselves as the origin of reionization, rather than early object formation, introducing an extra period of heating motivated by the active character of the perturbations. Using reasonable parameters, this leads to four pos

J. B. Griffiths, J. Podolsky

A physical interpretation is presented of the general class of conformally flat pure radiation metrics that has recently been identified by Edgar and Ludwig. It is shown that, at least in the weak field limit, successive wave surfaces can be represented as null (half) hyperplanes rolled around a two-dimensional null cone. In the impulsive limit, the solution

Yu. F. Pirogov, O. V. Zenin

In the framework of the two-loop renormalization group, the global profile of the Standard Model (SM) in its full parameter space is investigated up to the scale of the gauge singularity. The critical Higgs masses bordering the strong coupling, unstable and the safe regions are explicitly found. Restrictions on the Higgs boson mass as a function of a cutoff

J. R. Bond, A. H. Jaffe, L. E. Knox

Powerful constraints on theories can already be inferred from existing CMB anisotropy data. But performing an exact analysis of available data is a complicated task and may become prohibitively so for upcoming experiments with \gtrsim10^4 pixels. We present a method for approximating the likelihood that takes power spectrum constraints, e.g., ``band-powers&#

Franz Gerl, Annette Zippelius

We calculate the coefficient of restitution, $ε$, starting from a microscopic model of elastic disks. The theory is shown to agree with the approach of Hertz in the quasistatic limit, but predicts inelastic collisions for finite relative velocities of two approaching disks. The velocity dependence of $ε$ is calculated numerically for a wide range of velociti

Hagen Kleinert

We develop a method for extracting accurate critical exponents from perturbation expansions of the O(n)-symmetric nonlinear sigma-model in D=2+ epsilon dimensions. This is possible by considering the epsilon-expansions in this model as strong-coupling expansions of functions of the variable tildevarepsilon = 2(4-D)/(D-2), whose first five weak-coupling expan

Igor Pesando

We show explicitly that the two recently proposed actions for the type IIB superstring propagating on AdS_{5} X S_{5} agree completely.

Stephen Serjeant, Carlotta Gruppioni, Seb Oliver

We present a new determination of the local volume-averaged star formation rate from the 1.4 GHz luminosity function of star forming galaxies. Our sample, taken from the B<=12 Revised Shapley-Ames catalogue (231 normal spiral galaxies over effective area 7.1 sr) has ~100% complete radio detections and is insensitive to dust obscuration and cirrus contaminati

J. R. Forshaw, J. Papavassiliou, C. Parrinello

We argue that the massive Yang-Mills model of Kunimasa and Goto, Slavnov, and Cornwall, in which massive gauge vector bosons are introduced in a gauge-invariant way without resorting to the Higgs mechanism, may be useful for studying diffractive scattering of strongly interacting particles. We perform in this model explicit calculations of S-matrix elements

Y. Blum, P. K. Coyle, S. Elitzur, E. Rabinovici

We investigate, through Monte-Carlo simulations, the nature of the second order point in a $Z_2$ (Bosonic) + $Z_2$ gauge theory in four dimensions. Detailed analysis of the critical exponents point to the Ising universality class. Relevancy to extended models and possible Non-Gaussian behavior is discussed.

V. Buzek, R. Derka, S. Massar

A quantum clock must satisfy two basic constraints. The first is a bound on the time resolution of the clock given by the difference between its maximum and minimum energy eigenvalues. The second follows from Holevo&#39;s bound on how much classical information can be encoded in a quantum system. We show that asymptotically, as the dimension of the Hilbert s

Changhyun Ahn, Kyungho Oh, Radu Tatar

We study AdS/CFT correspondence in four dimensional N=1 field theories realized on the worldvolume of D3 branes near the intersections between D7 and D7&#39; branes in F theory studied by Aharony et al. We consider the compactification of F theory on elliptically fibered Calabi-Yau threefolds corresponding to two sets of parallel D7 branes sharing six spacet

Harold Widom

In a 1977 paper of McCoy, Tracy and Wu there appeared for the first time the solution of a Painlevé equation in terms of Fredholm determinants of integral operators. This equation is $ψ&#39;&#39;(t)+t^{-1}ψ&#39;(t)=(1/2) \sinh 2ψ+2αt^{-1} \sinhψ$, a special case of the Painlevé III equation. The proof in the cited paper is complicated, and the purpose of thi

M. Haragus-Courcelle, D. H. Sattinger

Uniform estimates for the decay structure of the $n$-soliton solution of the Korteweg-deVries equation are obtained. The KdV equation, linearized at the $n$-soliton solution is investigated in a class $\WW$ consisting of sums of travelling waves plus an exponentially decaying residual term. An analog of the kernel of the time-independent equation is proposed

A. Lima-Santos

We discuss some algebraic setting of chiral $SU(N)_{k}$ models in terms of the statistical dimensions of their fields. In particular, the conformal dimensions and the central charge of the chiral $SU(N)_{k}$ models are calculated from their braid matrices. Futhermore, at level K=2, we present the characteristic polynomials of their fusion matrices in a facto