May 1998 arXiv papers — page 11

ZEUS Collaboration

The inclusive forward jet cross section in deep inelastic $e^+p$ scattering has been measured in the region of $x$--Bjorken, ~$4.5 \cdot 10^{-4}$~ to ~$4.5 \cdot 10^{-2}$. This measurement is motivated by the search for effects of BFKL--like parton shower evolution. The cross section at hadron level as a function of \xbj is compared to cross sections predict

M. Heusler, N. Straumann, M. Volkov

It is shown that Julia-Zee dyons do not admit slowly rotating excitations. This is achieved by investigating the complete set of stationary excitations which can give rise to non-vanishing angular momentum. The relevant zero modes are parametrized in a gauge invariant way and analyzed by means of a harmonic decomposition. Since general arguments show that th

M. Gasperini

I present two examples in which the curvature singularity of a radiation-dominated Universe is regularized by (a) the repulsive effects of spin interactions, and (b) the repulsive effects arising from a breaking of the local gravitational gauge symmetry. In both cases the collapse of an initial, asymptotically flat state is stopped, and the Universe bounces

Naomichi Hatano, David R. Nelson

Recent literature on delocalization in non-Hermitian systems has stressed criteria based on sensitivity of eigenvalues to boundary conditions and the existence of a non-zero current. We emphasize here that delocalization also shows up clearly in eigenfunctions, provided one studies the product of left- and right-eigenfunctions, as required on physical ground

Dirk Helbing

Related to an idea of Lewin, a mathematical model for behavioral changes under the influence of a social field is developed. The social field reflects public opinion, social norms and trends. It is not only given by external factors (the environment) but also by the interactions of individuals. Two important kinds of interaction processes are distinguished:

K. Pinn, M. Rehwald, C. Wieczerkowski

We compute renormalization group fixed points and their spectrum in an ultralocal approximation. We study a case of two competing non-trivial fixed points for a three-dimensional real $N$-component field: the O(N)-invariant fixed point vs.~the cubic-invariant fixed point. We compute the critical value $N_{c}$ of the cubic $ϕ^{4}$-perturbation at the O(N)-fix

P. A. Marchetti, Zhao-Bin Su, Lu Yu

The Chern-Simons bosonization with U(1)xSU(2) gauge field is applied to 2-D t-J model in the limit t >> J, to study the normal state properties of underdoped cuprate superconductors. We prove the existence of an upper bound on the partition function for holons in a spinon background, and we find the optimal spinon configuration saturating the upper bound on

S. Fujimoto, N. Kawakami

The effects of Umklapp scattering on the zero-temperature conductance in one-dimensional quantum wires are reexamined by taking into account both the screening of external potential and the non-uniform chemical potential shift due to electron-electron interaction. It is shown that in the case away from half-filling the conductance is given by the universal v

K. Oerding, H. K. Janssen

Using field theoretic renormalization group methods we study the critical behavior of a driven diffusive system near a boundary perpendicular to the driving force. The boundary acts as a particle reservoir which is necessary to maintain the critical particle density in the bulk. The scaling behavior of correlation and response functions is governed by a new

R. Myrzakulov

Gauge equivalence between the two-dimensional continuous classical Heisenberg ferromagnets(CCHF) of spin 1/2 - the M-I equation with single site anisotropy and the Zakharov equation(ZE) is established for the easy axis case. The anisotropic CCHF is shown to be gauge equivalent to the isotropic CCHF.

R. Myrzakulov

The gauge equivalence between the (2+1)-dimensional Zakharov equations and (2+1)-dimensional integrable continuous Heisenberg ferromagnetic model is established. Also their integrable reductions are shown explicitly.

Hitoshi Seo, Hidetoshi Fukuyama

A possible ground state of NaV_2O_5 is proposed based on the Hartree approximation for both on-site and intersite Coulomb interactions. The results indicate that the intersite Coulomb interaction induces a zigzag type of charge disproportionation (i.e. charge ordering) along the ladders of V-ions resulting in the localized spins between neighboring ladders t

Hitoshi Seo, Hidetoshi Fukuyama

The origin of the spin gap behavior in the low-temperature dimerized phase of theta-(BEDT-TTF)_2RbZn(SCN)_4 has been theoretically studied based on the Hartree-Fock approximation for the on-site Coulomb interaction at absolute zero. Calculations show that, in the parameter region considered to be relevant to this compound, antiferromagnetic ordering is stabi

Hitoshi Seo, Hidetoshi Fukuyama

The nature of the insulating ground state in quasi-two-dimensional organic conductor lambda-(BETS)_2GaX_zY_{4-z}, where the existence of a spin gap is suggested by susceptibility measurement, has been studied theoretically. Hartree-Fock calculations at absolute zero temperature show that if the on-site Coulomb interaction exceeds some critical value, then an

I. L. Aleiner, A. V. Andreev

We consider adiabatic charge transport through an almost open quantum dot. We show that the charge transmitted in one cycle is quantized in the limit of vanishing temperature and one-electron mean level spacing in the dot. The explicit analytic expression for the pumped charge at finite temperature is obtained for spinless electrons. The pumped charge is pro

A. Abada, A. H. Bougourzi, S. Seba, B. Si-Lakhal

We discuss some properties of the exact four-spinon dynamical correlation function $S_4$ in the antiferromagnetic spin 1/2 $XXX$-model, the expression of which we derived recently. We show that the region in which it is not identically zero is different from and larger than the spin-wave continuum. We describe its behavior as a function of the neutron moment

R. O. Marzke, L. N. da Costa, P. S. Pellegrini, C. N. A. Willmer

We investigate the dependence of the local galaxy luminosity function on morphology using 5,404 galaxies from the recently enlarged Second Southern Sky Redshift Survey (SSRS2). Over the range -22 \le M_B \le -14 ($H_0 = 100 km/s/Mpc), the luminosity function of early-type galaxies is well fitted by a Schechter function with parameters M_*=-19.37^{+0.10}_{-0.

C. S. Reynolds, K. Iwasawa, C. S. Crawford, A. C. Fabian

We present an ASCA observation of the broad line radio galaxy 3C111. The X-ray spectrum is well described by a model consisting of a photoelectrically-absorbed power-law form. The inferred absorbing column density is significantly greater than expected on the basis of 21-cm measurements of Galactic HI. Whilst this may be due intrinsic absorption from a circu

S. L. Morris, J. B. Hutchings, R. G. Carlberg, H. K. C. Yee

We discuss the galaxy population of the rich cluster MS1621.5+2640 at z=0.4274, based on spectra and imaging in a field of size 9 arcmin by 23 arcmin (~2 by 5 h**-1 Mpc). The sample comprises 277 galaxies, of which 112 are cluster members, 7 are `near-members&#39;, and 47 are field galaxies in the redshift range 0.37<=z<=0.50. The results are analyzed and co

X. Luri, A. E. Gomez, J. Torra, F. Figueras

The LM method, designed to exploit the Hipparcos data to obtain luminosity calibrations, is applied to derive luminosity calibrations for RR Lyrae and classical Cepheids. From these calibrations the distance to the Large Magellanic Cloud (LMC) is estimated. The distance moduli provided by the two calibrations are in good agreement, giving a value of 18.3m, w

A. M. Read, W. Pietsch

We report here the results of high-resolution and spectral imaging X-ray observations, with both the ROSAT HRI and PSPC, of the field surrounding the nearby Seyfert galaxy IC4329A. Many point sources are detected, the brightest being associated with IC4329A itself, having an extremely bright Lx of 6x10e43erg/s, and spectral properties compatible with a singl

M. Zboril, P. North

We present an abundance analysis of light elements in He-rich stars. The analysis is based on both low and high resolution observations collected at ESO, La Silla, Chile in the optical region and includes 6 standards and 21 He-rich stars. Light-element abundances display a diverse pattern: they range from under-solar up to above-solar values.

P. J. E. Peebles

A companion paper presents a worked model for evolution through inflation to initial conditions for an isocurvature model for structure formation. It is shown here that the model is consistent with the available observational constraints that can be applied without the help of numerical simulations. The model gives an acceptable fit to the second moments of

M. Ishida, J. Greiner, R. A. Remillard, C. Motch

We present X-ray data of RX J1802.1+1804 obtained by ASCA. Although it shows a clear orbital intensity modulation with an amplitude of nearly 100% below 0.5 keV in ROSAT data, the ASCA light curves are nearly flat except for a possible dip lasting about one-tenth of the orbital period. We discuss this within the model assumption of a stream-eclipsing geometr

G. M. Wahlgren

We describe the ultraviolet spectra of the Ap star alpha^2 CVn that have been acquired with the Hubble Space Telescope and the nature of the optical region analyses for its rotational velocity and elemental abundances that have been undertaken in support of the ultraviolet data.

A. V. Yushchenko, V. F. Gopka, V. L. Khokhlova, F. A. Musaev

We report the results of abundance determination for the components of the SB2 star 66 Eri (M_A/M_B=0.97) from high resolution CCD echelle spectra with S/N>=100 taken with the 1-m telescope of Special Astrophysical Observatory (Zelenchuck, Russia). The atmospheric parameters of the components were determined using all available photometric, spectrophotometri

J. A. Peacock

This paper reviews the measurements of galaxy correlations at high redshifts, and discusses how these may be understood in models of hierarchical gravitational collapse. The clustering of galaxies at redshift one is much weaker than at present, and this is consistent with the rate of growth of structure expected in an open universe. If $Ω=1$, this observatio

I. Stateva, T. Ryabchikova, I. Iliev

We carried out a detailed analysis of the helium lines at 4921, 5876 and 6678 A in the spectra of the HgMn stars HD 58661, HD 172044, HD 185330 and HD 186122. For the first of these lines, the isotopic shift reaches +0.33 A for pure 3He, while for the last one, the maximum shift is +0.50 A. The 5876 line does not show any significant isotopic shift and is ch

T. Ryabchikova, N. Piskunov, I. Savanov, F. Kupka

We report the first identification of the Eu III lambda 6666.317 line in optical spectra of CP stars. This line is clearly present in the spectra of HR 4816, 73 Dra, HR 7575, and beta CrB, while it is marginally present or absent in spectra of the roAp stars alpha Cir, gamma Equ, BI Mic, 33 Lib, and HD 24712.

T. Ryabchikova, V. Malanushenko, S. J. Adelman

We performed a spectroscopic study of the SB2 Mercury-Manganese star alpha And. Our measurements of the secondary&#39;s radial velocities result in improved orbital elements. The secondary shows abundances typical of the metallic-line stars: a Ca deficiency, small overabundances of the iron-peak elements, and 1.0 dex overabundances of Sr and Ba.

L. C. Popovic, M. S. Dimitrijevic

In order to provide atomic data needed for astrophysical investigations, a set of electron-impact broadening parameters for ionized rare-earth element lines should be calculated. We are going to calculate the electron-impact broadening parameters for more than 50 transitions of ionized rare-earth elements. Taking into account that the spectra of these elemen

Takashi Nakamura, Ryoichi Nishi

We propose to search for MACHOs by observing EAGLE (Extremely Amplified Gravitational LEnsing) events of a majority of dim stars. This search is independent of the usual one. For the detection limit of EAGLE (about 20 mag), about 100 f (τ^{LMC} / 3 \times 10^{-7}) (100 days / <t>) EAGLE events/y are expected to result from all the dim stars in LMC. Here τ^{L

Adam G. Riess, Alexei V. Filippenko, Peter Challis, Alejandro Clocchiattia

We present observations of 10 type Ia supernovae (SNe Ia) between 0.16 < z < 0.62. With previous data from our High-Z Supernova Search Team, this expanded set of 16 high-redshift supernovae and 34 nearby supernovae are used to place constraints on the Hubble constant (H_0), the mass density (Omega_M), the cosmological constant (Omega_Lambda), the deceleratio

Brian P. Schmidt, Nicholas B. Suntzeff, M. M. Phillips, Robert A. Schommer

The High-Z Supernova Search is an international collaboration to discover and monitor type Ia supernovae (SN Ia) at $z > 0.2$ with the aim of measuring cosmic deceleration and global curvature. Our collaboration has pursued a basic understanding of supernovae in the nearby Universe, discovering and observing a large sample of objects, and developing methods

Dumitru Baleanu

We present the conditions when a Killing-Yano tensor becomes a Nambu tensor. We have shown that in the flat space case all Killing-Yano tensors are Nambu tensors. In the case of Taub-NUT metric and Kerr-Newmann metric we found that a Killing-Yano tensor of order two generate a Nambu tensor of order three.

Eckehard Hess, Thomas Schick

The L^2-torsion is an invariant defined for compact L^2-acyclic manifolds of determinant class, for example odd dimensional hyperbolic manifolds. It was introduced by John Lott and Varghese Mathai and computed for hyperbolic manifolds in low dimensions. In this paper we show that the L^2-torsion of hyperbolic manifolds of arbitrary odd dimension does not van

D. Muenter, T. Doderer, H. Pressler, S. Keil

The statics and dynamics of magnetic flux quanta (fluxons) in long annular Josephson tunnel junctions have been investigated. Pinning by interaction of the fluxon field outside the junction with the superconducting wiring has been observed in spatially resolving measurements using low-temperature scanning electron microscopy. We were able to influence the ch

Brian P. Dolan

We explore the consequences of introducing a complex conductivity into the quantum Hall effect. This leads naturally to an action of the modular group on the upper-half complex conductivity plane. Assuming that the action of a certain subgroup, compatible with the law of corresponding states, commutes with the renormalisation group flow, we derive many prope

W. Melnitchouk, J. Speth, A. W. Thomas

We explore the feasibility of directly extracting the large-x valence d/u ratio through a measurement of pions in the current fragmentation region of semi-inclusive deep-inelastic scattering from protons.

S. S. Deshingkar, P. S. Joshi, I. H. Dwivedi

We examine here the nature of the central singularity forming in the spherically symmetric collapse of a dust cloud and it is shown that this is always a strong curvature singularity where gravitational tidal forces diverge powerfully. An important consequence is that the nature of the naked singularity forming in the dust collapse turns out to be stable aga

Igor Batalin, Robert Marnelius

A binary expression in terms of operators is given which satisfies all the quantum counterparts of the algebraic properties of the classical antibracket. This quantum antibracket has therefore the same relation to the classical antibracket as commutators to Poisson brackets. It is explained how this quantum antibracket is related to the classical antibracket

M. Brunetti, E. Coccia, V. Fafone, F. Fucito

In this paper we analyze the signal emitted by a compact binary system in the Jordan-Brans-Dicke theory. We compute the scalar and tensor components of the power radiated by the source and study the scalar waveform. Eventually we consider the detectability of the scalar component of the radiation by interferometers and resonant-mass detectors.

H. Aratyn

This note develops an explicit construction of the constrained KP hierarchy within the Sato Grassmannian framework. Useful relations are established between the kernel elements of the underlying ordinary differential operator and the eigenfunctions of the associated KP hierarchy as well as between the related bilinear concomitant and the squared eigenfunctio

Asim Gangopadhyaya, Jeffry V. Mallow, Uday P. Sukhatme

Exactly solvable potentials of nonrelativistic quantum mechanics are known to be shape invariant. For these potentials, eigenvalues and eigenvectors can be derived using well known methods of supersymmetric quantum mechanics. The majority of these potentials have also been shown to possess a potential algebra, and hence are also solvable by group theoretical

Jens Bolte, Stefan Keppeler

We investigate the Dirac equation in the semiclassical limit \hbar --> 0. A semiclassical propagator and a trace formula are derived and are shown to be determined by the classical orbits of a relativistic point particle. In addition, two phase factors enter, one of which can be calculated from the Thomas precession of a classical spin transported along the

G. Kurizki, A. E. Kozhekin, A. G. Kofman, M. Blaauboer

We show that optical tachyonic dispersion corresponding to superluminal (faster than-light) group velocities characterizes parametrically amplifying media. The turn-on of parametric amplification in finite media, followed by illumination by spectrally narrow probe wavepackets, can give rise to transient tachyonic wavepackets. In the stable (sub-threshold) op

David A. Meyer

Finite precision measurement factors the Hilbert space of a quantum system into a tensor product $H_{coarse} \otimes H_{fine}$. This is mathematically equivalent to the partition into system and environment which forms the arena for decoherence, so we describe the consequences of the inaccessibility of $H_{fine}$ as scale decoherence. Considering the experim

K. Jungmann

A new superferric magnetic storage ring with highly homogeneous field at 1.45 T and weak electrostatic focussing is described which has been set up at the Brookhaven National Laboratory (BNL), USA, for a precision measurement of the magnetic anomaly of the muon. The toroidal storage volume has a radius of 7 m and a diameter of 9 cm. Precision magnetic field

M1S2S-Collaboration

A new measurement of the 1S-2S energy splitting of muonium by Doppler-free two-photon spectroscopy has been performed at the Rutherford Appleton Laboratory in Chilton, Didcot, UK. Increased accuracy is expected compared to a previous experiment. Spectroscopy of this transistion promises an improvement of the muon mass value.

K. Jungmann

The hydrogen-like muonium atom ($μ^+e^-$) consists of a positive muon ($μ^+$) and an electron ($e^-$). Since it was first observed by Hughes et al. in 1960, a series of precision experiments could be carried out testing bound state Quantum Electrodynamics (QED) and the nature of the muon as a point-like leptonic particle. Precision values for fundamental con

J. J. Hope, G. M. Moy, C. M. Savage

This paper has been withdrawn, as further work has shown that an atom laser as described by the model herein does not have a steady state, so it doesn&#39;t matter much what it would look like.

V. Emel&#39;yanov, A. Khodinov, S. R. Klein, R. Vogt

We explore how nuclear modifications to the free nucleon structure functions (also known as shadowing) affect heavy quark production in collisions at different impact parameters. We assume that the nuclear modifications arise from a density dependent effect such as gluon recombination and are thus proportional to the local density. We calculate the dependenc

Yu. N. Uzikov

It is shown that owing to a dominance of $np-$pair transfer mechanism of backward elastic $p^3He$- scattering for incident proton kinetic energies $T_p>1$ GeV the cross section of this process is defined mainly by the values of the Faddeev component of the wave function of $^3He$ nucleus, $ϕ^{23}({\bf q}_{23}, {\bf p}_1)$, at high relative momenta $q_{23}> 0

G. G. Athanasiu, E. G. Floratos, S. Nicolis

We develop number theoretic tools that allow to perform computations relevant for the quantum mechanics over finite fields of arbitrary, odd size, with the same speedup that is enjoyed by the Fast Fourier Transform.

Martina Brueck

An equifocal submanifold M of a symmetric space N of compact type induces a foliation with singular leaves on N. In this paper we will show how to reconstruct the equifocal foliation starting from one of the singular leaves, the so-called focal manifolds. To be more concrete: The equifocal submanifold is equal to a partial tube B around the focal manifold an

Peter Magyar, Jerzy Weyman, Andrei Zelevinsky

We classify all products of flag varieties with finitely many orbits under the diagonal action of the general linear group. We also classify the orbits in each case and construct explicit representatives. This generalizes the classical Schubert decompostion, which states that the GL(n)-orbits on a product of two flag varieties correspond to permutations. Our

B. Enriquez, V. Rubtsov

This is a survey of our construction of current algebras, associated with complex curves and rational differentials. We also study in detail two classes of examples. The first is the case of a rational curve with differentials $z^n dz$; these algebras are ``building blocks&#39;&#39; for the quantum current algebras introduced in our earlier work. The second

Matthias Burkardt

Naively, helicity flip amplitudes for fermions seem to vanish in the chiral limit of light-front QCD, which would make it nearly impossible to generate a small pion mass in this framework. Using a simple model, it is illustrated how a large helicity flip amplitude is generated dynamically by summing over an infinite number of Fock space components. While the

Maximo Banados, Andres Gomberoff, Cristian Martinez

Anti-de Sitter space with identified points give rise to black-hole structures. This was first pointed out in three dimensions, and generalized to higher dimensions by Aminneborg et al. In this paper, we analyse several aspects of the five dimensional anti-de Sitter black hole including, its relation to thermal anti-de Sitter space, its embedding in a Chern-

A. Campos, K. Holland, U. -J. Wiese

As argued by Witten on the basis of M-theory, QCD strings can end on domain walls. We present an explanation of this effect in the framework of effective field theories for the Polyakov loop and the gluino condensate in N=1 supersymmetric QCD. The domain walls separating confined phases with different values of the gluino condensate are completely wet by a l

H. Grosse, P. Presnajder

A free spinor field on a noncommutative sphere is described starting from a canonical realization of the enveloping algebra U(u(2|1)). The gauge extension of the model - the Schwinger model on a noncommutative sphere is defined and the model is quantized. The model contains only finite number degrees of freedom and is nonperturbatively UV-regular. The chiral

B. L. Julia

Duality symmetries of supergravity theories are powerful tools to restrict the number of possible actions, to link different dimensions and number of supersymmetries and might help to control quantisation. (Hodge-Dirac-)Dualisation of gauge potentials exchanges Noether and topological charges, equations of motion and Bianchi identities, internal rigid symmet

Chung-I Tan

The most important consequence of Pomeron being a pole is the factorization property. However, due to Pomeron intercept being greater than 1, the extrapolated single diffraction dissociation cross section based on a classical triple-Pomeron formula is too large leading to a potential unitarity violation at Tevatron energies. It is our desire here to point ou

Alfonso R. Zerwekh, Rogerio Rosenfeld

We study the process $e^+ e^- \to γγν\barν$ in the context of a strong electroweak symmetry breaking model, which can be a source of events with two photons and missing energy at LEP2. We investigate bounds on the model assuming that no deviation is observed from the Standard Model within a given experimental error.

M. A. Doncheski, R. W. Robinett

Standard radiation zeros arise from the factorization properties of tree-level amplitudes involving a massless photon and can occur when all charged particles in the initial and final state have the same sign. We investigate how several different processes involving new scalar particles beyond the standard model may exhibit radiation zeros and how this struc

W. Beenakker, F. A. Berends, A. P. Chapovsky

In this letter it is shown how final-state QED corrections to the production of a pair of resonances can distort the line shape of such a resonance in a sizeable way. This effect depends on the definition of the line shape and can reach up to 30%, depending on the final state. The mechanism is first displayed for a particular case of ZZ production, for which

S. Munier

High energy factorization predictions for F2c are derived using BFKL resummations of leading logs for the proton structure functions at HERA. A theoretical non-perturbative uncertainty on the factorization scheme is taken into account by considering two different approaches for modelling the proton. The parameters are fixed by a fit of F2 at small x. The res

R. Peschanski

The Good-Walker mechanism for diffraction is shown to provide a link between total and diffractive structure functions and to be relevant for QCD calculations at small x_{Bj}. For Deep-Inelastic scattering on a small-size target (cf. an onium) the r\^ ole of Good-Walker ``diffractive eigenstates&#39;&#39; is played by the QCD dipoles appearing in the $1/N_C$

G. P. Salam

This talk discusses and explains the two-loop corrections, also known as the Milan factor, for power corrections to jet-shape observables.

G. P. Salam

Results are presented on structure functions and final state properties within the CCFM approach. Traditionally used forms of the CCFM equation have difficulty fitting the F_2 data, predicting too fast a growth at small x. A solution can be found in a particular treatment of formally subleading (1-z) terms, which dampens very considerably the small-x growth.

A. Hebecker, P. V. Landshoff

The factorisation of the hard amplitude for exclusive meson production in deep inelastic scattering is considered in the framework of a simple model. It is demonstrated explicitly how gauge invariance ensures the cancellation of non-factorising contributions.

Muneyuki Ishida, Shin Ishida, Taku Ishida

In a series of previous papers the present authors and collaborators have shown strong evidence for existence of the long-sought sigma-particle by analyzing the pi pi-scattering and pi pi-production processes, applying, respectively, the IA method and the VMW method. In this paper we examine the relation between the scattering amplitude T and the production

W. Bietenholz

We give a prescription how to include a chemical potential μinto a general lattice action. This inclusion does not cause any lattice artifacts. Hence its application to an improved - or even perfect - action at μ=0 yields an improved resp. perfect action at arbitrary μ. For short-ranged improved actions, a good scaling behavior holds over a wide region, and

K. Jungmann

Quantum Electrodynamics describes electromagnetic interactions of free muons and of muon and electron in the muonium atom to very high accuracy. Contributions of other and yet unknown interactions can be investigated in precision experiments, e.g. by searching for muonium-antimuonium conversion and by measuring the muon magnetic anomaly.

K. Jungmann

A positive muon ($μ^+$) and an electron ($e^-$) form the the hydrogen-like muonium atom ($M$=$μ^+ e^-$). Since it consists of two leptonic particles which are according to present knowledge point-like, accurate calculations of its level energies can be performed in the framework of standard theory. In particular, the theoretical description of this system is

L. Willmann, K. Jungmann

The observed interactions between particles are not fully explained in the successful theoretical description of the standard model to date. Due to the close confinement of the bound state muonium ($M = μ^+ e^-$) can be used as an ideal probe of quantum electrodynamics and weak interaction and also for a search for additional interactions between leptons. Of

V. Meyer, A. Grossmann, K. Jungmann, J. Merkel

A new experimental search for muonium-antimuonium conversion was conducted at the Paul Scherrer Institute, Villigen, Switzerland. The preliminary analysis yielded one event fulfilling all required criteria at an expected background of 1.7(2) events due to accidental coincidences. An upper limit for the conversion probability in 0.1 T magnetic field is extrac

Devis Iellici

One-loop effects for quantum fields living on manifolds containing conical singularities are investigated in the context of cosmic string background and of finite-temperature theory in the Rindler wedge or outside the horizon of a Schwarzschild black-hole.

Valerio Faraoni

The standard tenet that Brans-Dicke theory reduces to general relativity in the omega-tends-to-infinity limit has been shown to be false when the trace of the matter energy-momentum tensor vanishes. The issue is clarified in a new approach and the asymptotic behaviour of the Brans-Dicke scalar is rigorously derived.

Daniel ben-Avraham

Fisher waves have been studied recently in the specific case of diffusion-limited reversible coalescence, A+A<-->A, on the line. An exact analysis of the particles concentration showed that waves propagate from a stable region to an unstable region at constant speed, just as in Fisher&#39;s &#34;mean-field&#34; theory; but also that the wave front fails to r

Scott Wunsch

This paper presents a simple, one-dimensional model of a randomly advected passive scalar. The model exhibits anomalous inertial range scaling for the structure functions constructed from scalar differences. The model provides a simple computational test for recent ideas regarding closure and scaling for randomly advected passive scalars. Results suggest tha

Jane&#39; Kondev, Jesper L. Jacobsen

Exact results for the scaling properties of compact polymers on the square lattice are obtained from an effective field theory. The entropic exponent γ=117/112 is calculated, and a line of fixed points associated with interacting chains is identified; along this line γvaries continuously. Theoretical results are checked against detailed numerical transfer ma

B. A. Ivanov, H. J. Schnitzer, F. G. Mertens, G. M. Wysin

We calculate the magnon modes in the presence of a vortex in a circular system, combining analytical calculations in the continuum limit with a numerical diagonalization of the discrete system. The magnon modes are expressed by the S-matrix for magnon-vortex scattering, as a function of the parameters and the size of the system and for different boundary con

Ivanka Milosevic, B. Nikolic, M. Damnjanovic, Maja Krcmar

The irreducible representations of all of the 80 diperiodic groups, being the symmetries of the systems translationally periodical in two directions, are calculated. To this end, each of these groups is factorized as the product of a generalized translational group and an axial point group. The results are presented in the form of the tables, containing the

Osame Kinouchi, Suani T. R. Pinho, Carmen P. C. do Prado

We reconsider the treatment of Lise and Jensen (Phys. Rev. Lett. 76, 2326 (1996)) on the random neighbor Olami-Feder-Christensen stik-slip model, and examine the strong dependence of the results on the approximations used for the distribution of states p(E).

R. de Bruyn Ouboter, A. N. Omelyanchouk, E. D. Vol

We have analyzed the quantum interference effects in the macroscopic &#39;&#39;superconducting molecule&#39;&#39;. The composite system consists of two massive superconducting rings, each interrupted by a Josephson junction, which are at the same time weakly coupled with one another. The special case of coupling via the Josephson four-terminal junction is co

P. S. Swain, A. O. Parry

We consider an effective Hamiltonian description of critical wetting transitions in systems with short-range forces at a corrugated (periodic) wall. We are able to recover the results obtained previously from a `microscopic&#39; density-functional approach in which the system wets in a discontinuous manner when the amplitude of the corrugations reaches a cri

F. Igloi, H. Rieger

In a recent letter [PRL 80 (1998) 3539] Fisher, Le Doussal and Monthus report new predictions for the persistence properties of Sinai&#39;s model, which they obtain by using an approximate real space renormalization group scheme. In this comment we show that these predictions can be derived in a rigorous and more transparent way by reducing the quantities of

M. -P. Kuittu, M. Haataja, N. Provatas, T. Ala-Nissila

We consider the dynamics and kinetic roughening of interfaces embedded in uniformly random media near percolation treshold. In particular, we study simple discrete ``forest fire&#39;&#39; lattice models through Monte Carlo simulations in two and three spatial dimensions. An interface generated in the models is found to display complex behavior. Away from the

Dirk Helbing

A new representation of the exact time dependent solution of the discrete master equation is derived. This representation can be considered as contraction of the path integral solution of Haken. It allows the calculation of the probability distribution of the occurence time for each path and is suitable as basis of new computational solution methods.

M. Barthelemy, D. J. Bergman

In this article, we study the Faraday effect in a binary composite consisting of a dielectric matrix with metallic inclusions. We first use the replica trick together with a variational method in order to compute the effective permittivity tensor (in the quasi-static limit) of this composite in a static magnetic field. In order to find the scaling exponents

C. Riva, K. Varga, F. M. Peeters

A variational calculation of the ground state energy of a biexciton in a GaAs/AlGaAs quantum well is presented. The well width fluctuations leading to trapping of the biexcitons are modeled by a parabolic potential. The results obtained for different well widths are compared with recent experimental data. Good agreement is obtained both for the biexciton bin

Patrick Navez

We study the ground state of a uniform Bose gas at zero temperature in the Hartree-Fock-Bogoliubov (HFB) approximation. We find a solution of the HFB equations which obeys the Hugenholtz-Pines theorem. This solution imposes a macroscopic squeezing to the condensed state and as a consequence displays large particle number fluctuations. Particle number conserv

Guillermo Abramson, Damian H. Zanette

We analyze a system of globally coupled logistic maps with asynchronous updating. We show that its dynamics differs considerably from that of the synchronous case. For growing values of the coupling intensity, an inverse bifurcation cascade replaces the structure of clusters and ordering in the phase diagram. We present numerical simulations and an analytica

Chil-Min Kim, Geo-Su Yim, Jung-Wan Ryu, Young-Jai Park

It is reported that the characteristic relations of type-II and type-III intermittencies, with respective local Poincar$\acute{e}$ maps of $x_{n+1}= (1+ε)x_n + a x^3_n$ and $x_{n+1}= - (1+ε)x_n - a x^3_n$, are both $- ln (ε)$ under the assumption of uniform reinjection probability. However, the intermittencies have various characteristic relations such as $ε

J. C. Lee, A. C. Fabian, C. S. Reynolds, K. Iwasawa

We report on a 50 ks observation of the bright Seyfert 1 galaxy MCG--6-30-15 with the Rossi X-ray Timing Explorer. The data clearly show the broad fluorescent iron line (equivalent width ~ 250 eV), and the Compton reflection continuum at higher energies. A comparison of the iron line and the reflection continuum has enabled us to constrain reflective fractio

Benjamin C. Bromley, William H. Press, Huan Lin, Robert P. Kirshner

Galaxies in the Las Campanas Redshift Survey are classified according to their spectra, and the resulting spectral types are analyzed to determine if local environment affects their properties. We find that the luminosity function of early-type objects varies as a function of local density. Our results suggest that early-type galaxies (presumably ellipticals

A. G. Kim

Observations show that Type Ia Supernovae (SNe Ia) form a homogeneous class of objects. They share similar spectroscopic evolution, light-curve shapes, and peak absolute magnitudes. The slight departures from homogeneity that are observed can be used to produce a &#34;calibrated candle&#34; with corrected magnitudes with even smaller dispersion. The existenc

G. Vettolani, E. Zucca, R. Merighi, M. Mignoli

The ESO Slice Project (ESP) is a galaxy redshift survey extending over about 23 square degrees, in a region near the South Galactic Pole. The survey is ~85% complete to the limiting magnitude b_J=19.4 and consists of 3342 galaxies with redshift determination. The ESP survey is intermediate between shallow, wide angle samples and very deep, one-dimensional pe

P. J. E. Peebles

I present a specific worked example of evolution through inflation to the initial conditions for an isocurvature CDM model for structure formation. The model invokes three scalar fields, one that drives power law inflation, one that survives to become the present-day CDM, and one that gives the CDM field a mass that slowly decreases during inflation and so `