October 1999 arXiv papers — page 5

Francisco J. Herranz, Ramon Ortega, Mariano Santander

A new method to obtain trigonometry for the real spaces of constant curvature and metric of any (even degenerate) signature is presented. The method encapsulates trigonometry for all these spaces into a single basic trigonometric group equation. This brings to its logical end the idea of an absolute trigonometry, and provides equations which hold true for th

Omar Mustafa, Thabit Barakat

The shifted-l expansion technique (SLET) has been developed to get eigenvalues of Schrodinger equation in three (3D) and two dimensions (2D). SLET simply consists of 1/\bar{l} as a perturbation parameter, where \bar{l}=l-β, βis a suitable shift, l is the angular momentum quantum number for 3D-case, l=|m| for the 2D-case, and m is the magnetic quantum number.

Udriste Constantin, Bila Nicoleta

Using the symmetry group theory of second order PDEs, one finds the symmetry group associated to Tzitzeica surfaces partial differential equation. One studies the inverse problem and one shows that the Tzitzeica surfaces PDE is an Euler-Lagrange equation. One determines the variational symmetry group of the associated functional and one obtains the conservat

Zinovy Reichstein, Boris Youssin

Let G be an algebraic group defined over an algebraically closed field k of characteristic zero. We give a simple proof of the following result: if H^1(L, G) = {1} for some finitely generated field extension L/k of transcendence degree \ge 3 then H^1(K, G) = {1} for every field extension K/k.

Bila Nicoleta

One applies the symmetry group theory for study the partial differential equations of Tzitzeica surfaces theory. One finds infinitesimal symmetries, Lagrangians and a new solution of Titzeica equation.

Martin Schlichenmaier

For arbitrary compact quantizable Kaehler manifolds it is shown how a natural formal deformation quantization (star product) can be obtained via Berezin-Toeplitz operators. Results on their semi-classical behaviour (their asymptotic expansion) due to Bordemann, Meinrenken and Schlichenmaier are used in an essential manner. It is shown that the star product i

Shigeru Yamagami

A C*-tensor category with simple unit object is realized by von Neumann algebra bimodules of finite Jones index if and only if it is rigid.

David Auckly, Lev Kapitanski

In this paper we will discuss problems and techniques related to underactuated systems. We give a mathematical formulation of several problems arising from applications, review some standard and new techniques, and pose some interesting and challenging open questions.

Pere Ara, Gert K. Pedersen, Francesc Perera

Replacing invertibility with quasi-invertibility in Bass' first stable range condition we discover a new class of rings, the QB-rings. These constitute a considerable enlargement of the class of rings with stable rank one (B-rings), and include examples like the ring of endomorphisms of a vector space over a field F, and the ring of all row- and column-

Zinovy Reichstein, Boris Youssin

The following ``Key Lemma'' plays an important role in Parusinski's work on the existence of Lipschitz stratifications in the class of semianalytic sets: For any positive integer n, there is a finite set of homogeneous symmetric polynomials W_1,...,W_N in Z[x_1,...,x_n] and a constant M >0 such that |dx_i/x_i| \le M \max_{j = 1,..., N} |dW_j/W_j|

T. E. Clark, S. T. Love

Nontrivial twisted boundary conditions associated with extra compact dimensions produce an ambiguity in the value of the four dimensional coupling constants of the renormalizable interactions of the twisted fields' zero modes. Resolving this indeterminancy would require a knowledge of the exact form of the higher dimensional action including the coeffici

J. -S. Park

This paper is devoted to a general and self-contained approach to any cohomological field theory with Kähler structure.

B. de Carlos, J. M. Moreno

We consider domain walls that appear in supersymmetric SU(N) with one massive flavour. In particular, for N > 3 we explicitly construct the elementary domain wall that interpolates between two contiguous vacua. We show that these solutions are BPS saturated for any value of the mass of the matter fields. We also comment on their large N limit and their relev

W. Lerche

We review quantitative tests on the duality between the heterotic string on T^2 and F-theory on K3. On the heterotic side, certain threshold corrections to the effective action can be exactly computed at one-loop order, and the issue is to reproduce these from geometric quantities pertaining to the K3 surface. In doing so we learn about certain non-perturbat

M. Dubois-Violette, P. Furlan, L. K. Hadjiivanov, A. P. Isaev

The left and right zero modes of the level k SU(n) WZNW model give rise to a pair of isomorphic (left and right) mutually commuting quantum matrix algebras. For a deformation parameter q being an even (2h-th, h = k + n) root of unity each of these matrix algebras admits an ideal such that the corresponding factor algebra is finite dimensional. The structure

Louise Dolan, Edward Witten

In order to study vertex operators for the Type IIB superstring on AdS space, we derive supersymmetric constraint equations for the vertex operators in AdS3xS3 backgrounds with Ramond-Ramond flux, using Berkovits-Vafa-Witten variables. These constraints are solved to compute the vertex operators and show that they satisfy the linearized D=6, N=(2,0) equation

Yuly Billig

The goal of this paper is to give a representation-theoretic interpretation of the sine-Gordon equation. We consider a vertex operator representation of affine Kac-Moody algebra \hat{sl_2} on the space of differential operators. In this formulation, the tau-function becomes a function of non-commuting variables. Using the skew Casimir operators, we obtain a

S. Nagy, K. Sailer

It is shown that the vacuum of QED$_2$ in Minkowski spacetime does not favour a periodic electric mean field. The projected effective action exhibiting a genuine dependence on the non-vanishing background field has been introduced. The functional dependence of the energy density of the vacuum on the assumed periodic vacuum expectation value of the vector pot

Markus A. Luty, Raman Sundrum

We analyze in detail a specific 5-dimensional realization of a "brane-universe" scenario where the visible and hidden sectors are localized on spatially separated 3-branes coupled only by supergravity, with supersymmetry breaking originating in the hidden sector. Although general power counting allows order 1/M_{Planck}^2 contact terms between the tw

Glenn Barnich, Marc Henneaux, Tobias Hurth, Kostas Skenderis

The relation between the gauge-invariant local BRST cohomology involving the antifields and the gauge-fixed BRST cohomology is clarified. It is shown in particular that the cocycle conditions become equivalent once it is imposed, on the gauge-fixed side, that the BRST cocycles should yield deformations that preserve the nilpotency of the (gauge-fixed) BRST d

Yu. V. Gusev, A. I. Zelnikov

We revise the calculation of the one-loop effective action for scalar and spinor fields coupled to the dilaton in two dimensions. Applying the method of covariant perturbation theory for the heat kernel we derive the effective action in an explicitly covariant form that produces both the conformally invariant and the conformally anomalous terms.For scalar fi

Robert Harlander

Different viewpoints on the asymptotic expansion of Feynman diagrams are reviewed. The relations between the field theoretic and diagrammatic approaches are sketched. The focus is on problems with large masses or large external momenta. Several recent applications also for other limiting cases are touched upon. Finally, the pros and cons of the different app

Tao Han

We discuss the parameterization for electroweak gauge boson interactions without a light Higgs boson. We present the constraints on the anomalous gauge-boson couplings from the current experiments. We emphasize that the four-point couplings involving the longitudinal weak bosons are genuine to the underlying strong dynamics responsible for the electroweak sy

M. C. Gonzalez-Garcia

In this talk I review the present status of the atmospheric neutrino anomaly and discuss some solutions that have been presented in the literature to solve this problem. In particular I review the "standard" solution in terms of neutrino oscillations as well as alternative scenarios such as the possibility of flavour changing neutrino interactions with the E

Gavin P. Salam

Of late, the field of BFKL physics has been the subject of significant developments. The calculation of the NLL terms was recently completed, and they turned out to be very large. Techniques have been proposed to resum these corrections. These lectures provide an introduction to the BFKL equation and some of the recent developments, using DGLAP evolution as

Alekhin Sergey

We perform a NLO QCD analysis of the combined SLAC-BCDMS-NMC-E665-H1-ZEUS data on inclusive deep inelastic cross section. Particular attention was paid to the extraction of strong coupling constant $α_s$ and high twist (HT) contribution to the structure functions $F_2$ and $F_L$. It was shown that at small and moderate x there is a visible dependence of the

G. L. Gogiberidze, L. K. Gelovani, E. K. Sarkisyan

Features of dense groups, or spikes, of negative pions produced in Mg-Mg collisions at 4.3 GeV/c/nucleon are studied to search for a coherent, Cerenkov-like, mechanism of particle production process. We investigate the distributions of spike centers and, for the first time, the energy spectra of particles in spikes. The spike-center distributions are obtaine

A. A. Pankov

Fermion compositness, and other new physics which can be described by an exchange of very massive particles ($Z^\prime$ boson, leptoquarks, sparticles with R-parity violating couplings), can be manifest itself as the presence of a strong four-fermion contact interaction. For the processes $e^+e^-\to μ^+μ^-$, $τ^+τ^-$, $\bar{b}b$ and $\bar{c}c$ at a future $e

G. Ridolfi

We review the main results of next-to-leading order QCD analyses of polarized deep-inelastic scattering data, with special attention to the assessment of theoretical uncertainties.

J. Velasco, J. Perez-Peraza, A. Gallegos-Cruz, M. Alvarez-Madrigal

Proton-proton total cross sections are measured with present day high energy colliders up to 2 TeV in the centre-of-mass of the system (10^{15}) eV in the laboratory). Several parameterizations, very succesful at low energies, can then be used to extrapolate the measured values and get estimations of cross sections to higher energies (10^{17} eV). On the oth

Ambar Ghosal

It has been shown that unless the tri-linear R-parity violating coupling $λ_{i33}$ (i = 1, 2) is small enough ($λ_{i33}<$ ${10}^{-2}$ for MSSM and ${10}^{-3}$ for GMSB model),the partial decay width of photino decaying into &#39;photon + $ν_{e,μ}$&#39;, both in supergravity motivated (MSSM) and gauge mediated (GMSB) supersymmetric models are larger than the

K. Terasaki

Two body decays of B mesons are studied by decomposing their amplitude into a sum of factorizable and non-factorizable ones. The former is estimated by using a naive factorization while the latter is assumed to be dominated by dynamical contributions of various hadron states and is calculated by using a hard pion (or kaon) technique in the infinite momentum

L3 Collaboration

Extra spatial dimensions are proposed by recent theories that postulate the scale of gravity to be of the same order as the electroweak scale. A sizeable interaction between gravitons and Standard Model particles is then predicted. Effects of these new interactions in boson and fermion pair production are searched for in the data sample collected at centre-o

M. Artuso, R. Ayad, F. Azfar, A. Efimov

The CLEO III Ring Imaging Cherenkov detector uses LiF radiators to generate Cherenkov photons which are then detected by proportional wire chambers using a mixture of CH$_4$ and TEA gases. The first two photon detector modules which were constructed, were taken to Fermilab and tested in a beam dump that provided high momentum muons. We report on results usin

Ulrich H. Gerlach

The global Minkowski Bessel (M-B) modes, whose explicit form allows the identification and description of the condensed vacuum state resulting from the operation of a pair of accelerated refrigerators, are introduced. They span the representation space of the unitary representation of the Poincare group on 2-D Lorentz space-time. Their three essential proper

Gerard Clement

I present a new method to generate rotating solutions of the Einstein-Maxwell equations from static solutions, give several examples of its application, and discuss its general properties.

V. Dzhunushaliev, U. Kasper, D. Singleton

By studying multidimensional Kaluza-Klein theories, or gravity plus U(1) or SU(2) gauge fields it is shown that these theories possess similar flux tube solutions. The gauge field which fills the tube geometry of these solutions leads to a comparision with the flux tube structures in QCD. These solutions also carry a ``magnetic&#39;&#39; charge, Q, which for

Raul A. Enrique, Pascal Bellon

We study an alloy system where short-ranged, thermally-driven diffusion competes with externally imposed, finite-ranged, athermal atomic exchanges, as is the case in alloys under irradiation. Using a Cahn-Hilliard-type approach, we show that when the range of these exchanges exceeds a critical value, labyrinthine concentration patterns at a mesoscopic scale

N. A. Fromer, C. Schüller, D. S. Chemla, T. V. Shahbazyan

By means of degenerate four-wave mixing (FWM), we investigate the quantum coherence of electron-hole pairs in the presence of a two-dimensional electron gas in modulation-doped GaAs-AlGaAs quantum wells in the quantum Hall effect regime. With increasing magnetic field, we observe a crossover from Markovian to non-Markovian behavior, as well as large jumps in

A. Rosch

We present a theory of the magnetotransport in weakly disordered metals close to an antiferromagnetic quantum-critical point. The anisotropic scattering from critical spin fluctuations is strongly influenced by weak but isotropic scattering from small amounts of disorder. This leads to a large regime where the resistivity obeys a scaling form rho=rho_0+Delta

Estelle Pitard, Eugene I. Shakhnovich

We study the Langevin dynamics of a heteropolymer by means of a mode-coupling approximation scheme, giving rise to a set of coupled integro-differential equations relating the response and correlation functions. The analysis shows that there is a regime at low temperature characterized by out-of-equilibrium dynamics, with violation of time-translational inva

Shan-Ho Tsai, Alex Bunker, D. P. Landau

Spin-dynamics techniques have been used to perform large-scale simulations of the dynamic behavior of the classical Heisenberg antiferromagnet in simple cubic lattices with linear sizes $L\leq 60$. This system is widely recognized as an appropriate model for the magnetic properties of RbMnF$_3$. Time-evolutions of spin configurations were determined numerica

H. K. Janssen, O. Stenull

We study random networks of nonlinear resistors, which obey a generalized Ohm&#39;s law, $V\sim I^r$. Our renormalized field theory, which thrives on an interpretation of the involved Feynman Diagrams as being resistor networks themselves, is presented in detail. By considering distinct values of the nonlinearity r, we calculate several fractal dimensions ch

Andrea Gabrielli, Guido Caldarelli, Luciano Pietronero

We show that the introduction of thermal noise in Invasion Percolation (IP) brings the system outside the critical point. This result suggests a possible definition of SOC systems as ordinary critical systems where the critical point correspond to set to 0 one of the parameters. We recover both IP and EDEN model, for $T \to 0$, and $T \to \infty$ respectivel

T. Wegner, M. Potthoff, W. Nolting

We calculate the spin- and temperature-dependent local density of states for ferromagnetic Ni in the presence of a core hole at a distinguished site in the lattice. Correlations among the valence electrons and between valence and core electrons are described within a multi-band Hubbard model which is treated by means of second-order perturbation theory aroun

Bai-lin Hao

This is a review of a set of recent papers with some new data added. After a brief biological introduction a visualization scheme of the string composition of long DNA sequences, in particular, of bacterial complete genomes, will be described. This scheme leads to a class of self-similar and self-overlapping fractals in the limit of infinitely long constotue

T. Wegner, M. Potthoff, W. Nolting

CVV Auger electron spectra are calculated for a multi-band Hubbard model including correlations among the valence electrons as well as correlations between core and valence electrons. The interest is focused on the ferromagnetic 3d-transition metals. The Auger line shape is calculated from a three-particle Green function. A realistic one-particle input is ta

A. Ramsak, I. Sega, P. Prelovsek

We study the electron momentum distribution function (EMDF) for the two-dimensional t-t&#39;-J model doped with one hole on finite clusters by the method of twisted boundary conditions. The results quantitatively agree with our analytical results for a single hole in the antiferromagnetic background, based on the self-consistent Born approximation (SCBA). Mo

Kun Yang, S. L. Sondhi

We discuss the effects of a magnetic field applied parallel to the Cu-O ($ab$) plane of the high $T_c$ cuprate superconductors. After briefly reviewing the Zeeman effect of the field, we study the orbital effects, using the Lawrence-Doniach model for layered superconductors as a guide to the physics. We argue that the orbital effect is qualitatively differen

F. Molino, J. Appell, M. Filali, E. Michel

We study the structure and dynamics of a transient network composed of droplets of microemulsion connected by telechelic polymers. The polymer induces a bridging attraction between droplets without changing their shape. A viscoelastic behaviour is induced in the initially liquid solution, characterised in the linear regime by a stretched exponential stress r

Reginaldo A. Zara, Roberto N. Onody

A new kind of invasion percolation is introduced in order to take into account the inertia of the invader fluid. The inertia strength is controlled by the number N of pores (or steps) invaded after the perimeter rupture. The new model belongs to a different class of universality with the fractal dimensions of the percolating clusters depending on N. A blocki

V. V. Flambaum, M. Yu. Kuchiev

As it is well known there may arise situations when an interaction between electrons is attractive. A weak attraction should manifest itself strongly in 1D systems, since it can create two-electron bound states. This paper interprets the 0.7 $(2e^2/h)$ conductance structure, observed recently in a one-dimensional constriction, as a manifestation of two-elect

Koji Hukushima, Hajime Yoshino, Hajime Takayama

Aging phenomena of short-range Ising spin glass models have been investigated using Monte Carlo simulations. It is found that in the low-temperature spin-glass phase the mean domain size exhibits a crossover from a power-law growth associated with the critical fluctuation at the transition temperature to slower growth inherent in the low-temperature phase. T

L. Van Look, M. J. Van Bael, K. Temst, J. G. Rodrigo

We have studied flux pinning in thin superconducting Pb films covering a triangular array of submicron magnetic Au/Co/Au dots with in-plane magnetization. The rectangular dots can have two possible in-plane magnetic states: a single-domain state where the magnetization lies along the long axis of the dot and a multi-domain state. In this paper, we report on

Raphael Exartier, Luca Peliti

We introduce and solve a model of a thermometric measurement on a driven glassy system in a stationary state. We show that a thermometer with a sufficiently slow response measures a temperature higher than that of the environment, but that the measured temperature does not usually coincide with the effective temperature related to the violation of the Fluctu

Han-Jin Noh, Tschang-Uh Nahm, Jae-Young Kim, W. -G. Park

We have performed high resolution photoemission study of substitutionally disordered alloys Cu-Pt, Cu-Pd, Cu-Ni, and Pd-Pt. The ratios between alloy spectra and pure metal spectra are found to have dips at the Fermi level when the residual resistivity is high and when rather strong repulsive electron-electron interaction is expected. This is in accordance wi

S. -J. Oh, Wookje Kim, Wondong Kim, B. -H. Choi

We measured geometric and magnetic properties of Co films on the Pd(111) surface by x-ray photoelectron diffraction (XPD), x-ray magnetic circular dichroism (MCD) at the Co L_{2,3} edge, and the surface magneto-optical Kerr effect (SMOKE) measurements. Co thin films are found to grow incoherently with fcc island structure on the smooth Pd(111) substrate. Com

Domenico Giuliano, Arturo Tagliacozzo

An experiment is proposed of non perturbative tunneling in a Quantum dot connected to leads in a pillar configuration, which would shed light on the physics of the mesoscopic Kondo problem. We propose for the first time that what is coupled to the leads in the case of even number of electrons on the dot is not just the electrons on the QD, with their own spi

J. E. Hirsch

It is pointed out that in ferromagnetic metals a contribution to the Hall voltage arises when a non-zero spin current exists, which is generally the case in the presence of a charge current. This contribution is independent of any scattering effects and exists down to zero temperature. The sign of the resulting Hall coefficient may be either equal or opposit

Paolo Cermelli, Morton E. Gurtin, Giovanni Leoni

This note summarizes recent results in which modern techniques of the calculus of variations are used to obtain qualitative features of film-substrate interfaces for a broad class of interfacial energies. In particular, we show that the existence of a critical thickness for incoherency and the formation of interfacial dislocations depend strongly on the conv

E. Bogomolny

In many problems of quantum chaos the calculation of sums of products of periodic orbit contributions is required. A general method of computation of these sums is proposed for generic integrable models where the summation over periodic orbits is reduced to the summation over integer vectors uniquely associated with periodic orbits. It is demonstrated that i

Alessandro P. S. de Moura, Patricio S. Letelier

We investigate the occurrence chaos in the escape of test particles moving in the field of a Schwarzschild black hole surrounded by an external halo. The motion of both material particles and zero rest mass particles is considered. The chaos is characterized by the fractal dimension of boundary between the basins of the different escapes, which is a topologi

A. Lippi, R. Livi

The divergence of the heat conductivity in the thermodynamic limit is investigated in 2d-lattice models of anharmonic solids with nearest-neighbour interaction from single-well potentials. Two different numerical approaches based on nonequilibrium and equilibrium simulations provide consistent indications in favour of a logarithmic divergence in &#34;ergodic

J. Davoudi, A. R. Rastegar, M. R. Rahimi Tabar

We investigate non-perturbative results of inviscid forced Burgers equation supplemented to continuity equation in three-dimensions. The exact two-point correlation function of density is calculated in three-dimensions. The two-point correlator $<ρ(\bf x_1) ρ(\bf x_2)>$ behaves as $ |{\bf {x_1 - x_2}}|^{-α_3}$ and in the universal region $α_3 = 7/2$ while in

Paul B. Eskridge, Jay A. Frogel, Richard W. Pogge, Alice C. Quillen

We have determined the fraction of barred galaxies in the H-band for a statistically well-defined sample of 186 spirals drawn from the Ohio State University Bright Spiral Galaxy survey. We find 56% of our sample to be strongly barred at H, while another 16% is weakly barred. Only 27% of our sample is unbarred in the near-infrared. The RC3 and the Carnegie At

Xiaohu Wang, Abraham Loeb

Gamma-Ray Burst (GRB) afterglows are commonly interpreted as synchrotron emission from a relativistic blast wave produced by a point explosion in an ambient medium, plausibly the interstellar medium of galaxies. We calculate the amplitude of flux fluctuations in the lightcurve of afterglows due to inhomogeneities in the surrounding medium. Such inhomogeneiti

L. Drissen, J. -R. Roy, C. Robert, D. Devost

We present HST optical images and UV spectra, as well as ground-based near-infrared images of the high surface brightness giant HII region NGC 2363 (NGC 2366-I) and its surroundings. The massive star content of the southern end of the dwarf irregular galaxy NGC 2366 is investigated, with an emphasis on Wolf-Rayet and red supergiant stars, and we attempt the

Zeljko Ivezic, Maia Nenkova, Moshe Elitzur

DUSTY solves the problem of radiation transport in a dusty environment. The code can handle both spherical and planar geometries. The user specifies the properties of the radiation source and dusty region, and the code calculates the dust temperature distribution and the radiation field in it. The solution method is based on a self-consistent equation for th

John P. Hughes, Cara E. Rakowski, David N. Burrows, Patrick O. Slane

We present results from the first light observations of the Cassiopeia A (Cas A) supernova remnant (SNR) by the Chandra X-ray Observatory. The X-ray spectrum varies on all spatial scales down to the instrumental limit (0.02 pc at the SNR). Based on representative spectra from four selected regions we investigate the processes of nucleosynthesis and mixing in

Marc Postman

Our understanding of the cosmic history of galaxy clusters has recently been enhanced due to an extensive series of observations including faint spectroscopic data (especially those obtained at the Keck Observatory), deep optical and NIR imaging from the ground and in space, morphological data from HST, and new constraints on the evolution of the intracluste

Eli Livne

Delayed detonation in an exploding white dwarf, which propagates from an off-center transition point, rather than from a spherical transition shell, is described and simulated. The differences between the results of 2D simulations and the 1D case are presented and discussed. The two dimensional effects become significant in transition density below 3.e7 g/cm

A. Biviano, M. Ramella, W. Boschin, S. Bardelli

Using EFOSC2 at the 3.6m ESO telescope, we obtained redshifts for 68 galaxies in the field of six cluster candidates from the ESO Imaging Survey (EIS). The cluster candidates were selected in the EIS patches C and D and have estimated mean redshifts between z=0.5 and z=0.7. In the six candidate cluster fields, we identify possible systems of galaxies in the

F. Govoni, R. Falomo, G. Fasano, R. Scarpa

We present morphological and photometric properties of 79 low redshift (z<0.12) radio galaxies extracted from two radio flux limited samples of radio sources. All objects are imaged in the R band and for a subsample we have also obtained B band images. The sample includes sources of both FRI and FRII radio morphological type. Through the decomposition of the

T. Fukushige, D. C. Heggie

In this paper a cluster is modelled as a smooth potential (due to the cluster stars) plus the steady tidal field of the Galaxy. In this model there is a minimum energy below which stars cannot escape. Above this energy, however, the time scale on which stars escape varies with the orbital parameters of the star (mainly its energy) in a way which we attempt t

R. Pello, J-P. Kneib, J-F. Le Borgne, B. Fort

We discuss the first results obtained on the study of a sample of high-z galaxies (2 < z < 7), using the gravitational amplification effect in the core of lensing clusters. Sources are located close to the critical lines in clusters with well constrained mass distributions, and selected through photometric redshifts, computed on a large wavelength domain, an

Miguel A. Aloy, Ewald Mueller, Jose M. Ibanez, Jose M. Marti

We have studied the relativistic beamed outflow proposed to occur in the collapsar model of gamma-ray bursts. A jet forms as a consequence of an assumed energy deposition of $\sim 10^{50}- 10^{51}$ erg/s within a $30^{\circ}$ cone around the rotation axis of the progenitor star. The generated jet flow is strongly beamed ($\la$ few degrees) and reaches the su

Miguel A. Aloy, Jose M. Ibanez, Jose M. Marti, Jose L. Gomez

The multidimensional relativistic hydrodynamical code GENESIS has been used to obtain first results of {\it 3D} simulations of relativistic jets. We have studied the influence of a slight perturbation of the injection velocity field on the morphodynamics of otherwise axisymmetric relativistic jets.

J. Pons, J. Ma. Marti, E. Muller

We have generalised the exact solution of the Riemann problem in special relativistic hydrodynamics for arbitrary tangential flow velocities. The solution is obtained by solving the jump conditions across shocks plus an ordinary differential equation arising from the self-similarity condition along rarefaction waves, in a similar way as in purely normal flow

Hubert Lampeitl, Werner Hofmann

Observations of air showers with the stereoscopic HEGRA IACT system are usually carried out in a mode where all telescopes point in the same direction. Alternatively, one could take into account the finite distance to the shower maximum and orient the telescopes such that their optical axes intersect at the average height of the shower maximum. In this paper

J. E. Hibbard

HI spectral line mapping studies are a unique probe of morphologically peculiar systems. Not only does HI imaging often reveal peculiarities that are totally unsuspected at optical wavelengths, but it opens a kinematic window into the outer dynamics of these systems that is unmatched at any other wavelength. In this review I attempt to summarize what we have

R. P. Norris, A. Hopkins, R. J. Sault, R. D. Ekers

We present the first results from a series of radio observations of the Hubble Deep Field South and its flanking fields. Here we consider only those sources greater than 100 microJy at 20 cm, in an 8-arcmin square field that covers the WFPC field, the STIS and NICMOS field, and most of the HST flanking fields and complementary ground-based observations. We h

W. N. Brandt, S. C. Gallagher, A. Laor, Beverley J. Wills

Major flows of ionized gas are thought to be present in the nuclei of most luminous QSOs, and absorption by these flows often has a significant effect upon the observed X-ray continuum from the black hole region. We briefly discuss X-ray studies of this gas and attempts to determine its geometry, dynamics, and ionization physics. Our focus is on X-ray warm a

D. R. Phillips, I. R. Afnan, A. G. Henry-Edwards

Dimensional regularization is applied to the Lippmann-Schwinger equation for a separable potential which gives rise to logarithmic singularities in the Born series. For this potential a subtraction at a fixed energy can be used to renormalize the amplitude and produce a finite solution to the integral equation for all energies. This can be done either algebr

The SNO Collaboration

The Sudbury Neutrino Observatory is a second generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by compar

Ilya Shapiro, Joan Sola

A large value of the cosmological constant (CC) is induced in the Standard Model (SM) of Elementary Particle Physics because of Spontaneous Symmetry Breaking. To provide a small value of the observable CC one has to introduce the vacuum term which cancels the induced one at some point in the very far infrared cosmic scale. Starting from this point we investi

A. M. Egorov, A. E. Lobanov, A. I. Studenikin

Oscillations of neutrinos $\nu_L \leftrightarrow \nu_R$ in presence of an arbitrary electromagnetic field are considered. We introduce the Hamiltonian for the neutrino spin evolution equation that accounts for possible effects of interaction of neutrino magnetic $\mu$ and electric $\epsilon$ dipole moments with the transversal (in respect to the neutrino mom

Miloslav Dusek, Mika Jahma, Norbert Lütkenhaus

The use of linearly independent signal states in realistic implementations of quantum key distribution (QKD) enables an eavesdropper to perform unambiguous state discrimination. We explore quantitatively the limits for secure QKD imposed by this fact taking into account that the receiver can monitor to some extend the photon number statistics of the signals

R. N. Mohapatra, A. Perez-Lorenzana

If light sterile neutrinos are needed to understand the neutrino puzzles, as is currently indicated, a major theoretical challenge is to understand why its mass is so small. It is a more serious problem than understanding the small mass of the familiar neutrinos. We discuss a new way to solve this problem by identifying the sterile neutrino as gauge neutral

B. Linet

Without pretending to any rigour, we find a general expression of the electrostatic self-energy in static black holes with spherical symmetry. We determine the entropy bound of a charged object by assuming the existence of thermodynamics for these black holes. By combining these two results, we show that the entropy bound does not depend on the considered bl

Koji Hashimoto, Hiroyuki Hata, Sanefumi Moriyama

We study the structure of the monopole configuration in U(2) non-commutative super Yang-Mills theory. Our analysis consists of two steps: solving the BPS equation and then the eigenvalue equation in the non-commutative space. Calculation to the first non-trivial order in the non-commutativity parameter theta shows that the monopole exhibits a certain non-loc

S. Wakimoto, S. Ueki, Y. Endoh, K. Yamada

Systematic measurements of the magnetic susceptibility were performed on single crystals of lightly doped La2-xSrxCuO4 (x=0.03, 0.04 and 0.05). For all samples the temperature dependence of the in-plane magnetic susceptibility shows typical spin-glass features with spin-glass transition temperatures Tg of 6.3K, 5.5K and 5.0K for x=0.03, 0.04 and 0.05, respec

Richard J. Szabo, John F. Wheater

We describe a simple lattice model of higher-curvature quantum gravity in two dimensions and study the phase structure of the theory as a function of the curvature coupling. It is shown that the ensemble of flat graphs is entropically unstable to the formation of baby universes. In these simplified models the growth in graphs exhibits a branched polymer beha

Dario Grasso, Anna Rossi

We show that neutrino oscillations in matter are always accompanied by collective forces on the medium. This effect may produce interesting consequences for the background and the neutrino oscillations themselves. The force is maximal in the case of resonant neutrino conversion in the adiabatic regime. We study here the forces driven by $ν_e-ν_{μ,τ}$ and $ν_

D. Davidovic, M. Tinkham

We have studied tunneling into individual Au nanoparticles of estimated diameters 2-5 nm, at dilution refrigerator temperatures. The I-V curves indicate resonant tunneling via discrete energy levels of the particle. Unlike previously studied normal metal particles of Au and Al, in these samples we find that the lowest energy tunneling resonances are split in

F. Ricci-Tersenghi, F. Ritort

We study the non-equilibrium behavior of three-dimensional spin glasses in the Migdal-Kadanoff approximation, that is on a hierarchical lattice. In this approximation the model has an unique ground state and equilibrium properties correctly described by the droplet model. Extensive numerical simulations show that this model lacks aging in the remanent magnet

J. M. Carmona, N. Michel, J. Richert, P. Wagner

We discuss the implications of finite size effects on the determination of the order of a phase transition which may occur in infinite systems. We introduce a specific model to which we apply different tests. They are aimed to characterise the smoothed transition observed in a finite system. We show that the microcanonical ensemble may be a useful framework

G. Jackeli, N. B. Perkins, N. M. Plakida

Phase diagram of half-doped perovskite manganites is studied within the extended double-exchange model. To demonstrate the role of orbital degrees of freedom both one- and two-orbital models are examined. A rich phase diagram is obtained in the mean-field theory at zero temperature as a function of J (antiferromagnetic (AFM) superexchange interaction) and V

Atsushi Hosaka, Miho Takayama, Hiroshi Toki

We study electromagnetic transitions of excited baryons in a deformed oscillator quark model, where baryon excited states are described as rotational bands of deformed intrinsic states. We describe all necessary tools to compute transition amplitudes in multipole basis, which are then related to the commonly used helicity amplitudes. We pay a special attenti

G. Akemann, P. H. Damgaard

We prove a Mahoux-Mehta--type theorem for finite-volume partition functions of SU(N_c\geq 3) gauge theories coupled to fermions in the fundamental representation. The large-volume limit is taken with the constraint V << 1/m_π^4. The theorem allows one to express any k-point correlation function of the microscopic Dirac operator spectrum entirely in terms of

Boyu Hou, Kangjie Shi, Ruihong Yue, Shaoyou Zhao

By using algebraic Bethe ansatz method, we give the Hamitonian of the spin-1 XXX chain associated with $sl_2$ with two boundary impurities.