April 2001 arXiv papers — page 9

Boris Kastening

The partition function of the two-dimensional Ising model with zero magnetic field on a square lattice with m x n sites wrapped on a torus is computed within the transfer matrix formalism in an explicit step-by-step approach inspired by Kaufman's work. However, working with two commuting representations of the complex rotation group SO(2n,C) helps us avo

P. F. Kelly, Terry Pilling

We bring to bear an empirical model of the distribution of twin primes and produce two distinct results. The first is that we can make a quantitative probabilistic prediction of the occurrence of gaps in the sequence of twins within the primes. The second is that the ``high jumper'' i.e., the separation with greatest likelihood (in terms of primes) i

Massimo Di Pierro, Estia Eichten

A detailed study of orbital and radial excited states in D, Ds, B and B_s systems is performed. The chiral quark model provides the framework for the calculation of pseudoscalar meson (pi, K, ...) hadronic transitions among heavy-light excited and ground states. To calculate the excited states masses and wavefunctions, we must resort to a relativistic quark

A. Leksanov, J. Alster, G. Asryan, Y. Averichev

The transparency of carbon for (p,2p) quasi-elastic events was measured at beam energies ranging from 6 to 14.5 GeV at 90 degrees c.m. The four momentum transfer squared q*q ranged from 4.8 to 16.9 (GeV/c)**2. We present the observed energy dependence of the ratio of the carbon to hydrogen cross sections. We also apply a model for the nuclear momentum distri

K. Z. Stanek, P. M. Garnavich, S. Jha, R. E. Kilgard

(Abridged) We present the earliest optical observations of the optical counterpart to the GRB 010222, obtained with the FLWO 1.2-m telescope in UBVRI passbands, starting 3.64 hours after the burst. We also present late R-band observations of the afterglow obtained with the 1.8-m VATT ~25 days after the burst. The temporal analysis of our data joined with pub

S. Typel, R. Shyam

We investigate the breakup of the one-neutron halo nuclei 11Be and 19C within a dynamical model of the continuum excitation of the projectile. The time evolution of the projectile in coordinate space is described by solving the three-dimensional time dependent Schroedinger equation, treating the projectile-target (both Coulomb and nuclear) interaction as a t

V. Dupuis, E. Vincent, J. -P. Bouchaud, J. Hammann

We have compared aging phenomena in the Fe_{0.5}Mn_{0.5}TiO_3 Ising spin glass and in the CdCr_{1.7}In_{0.3}S_4 Heisenberg-like spin glass by means of low-frequency ac susceptibility measurements. At constant temperature, aging obeys the same `$ωt$ scaling' in both samples as in other systems. Investigating the effect of temperature variations, we find t

D. R. Ballantyne, A. C. Fabian

We present results from fitting ionized accretion disc models to three long ASCA observations of the Seyfert 1 galaxy MCG--6-30-15. All three datasets can be fit by a model consisting of ionized reflection from the inner region of the accretion disc (with twice solar Fe abundance) and a separate diskline component from farther out on the the disc. The diskli

Marc Dhalle, Pierre Toulemonde, Concetta Beneduce, Nicolas Musolino

The critical current density of four MgB2 samples was measured inductively and for one of them also by transport. Pure phased and dense bulk samples yield a critical current density which in value, as well as in its magnetic field and temperature dependence, is essentially the same as the intra-granular current density measured in a dispersed powder. Also th

R. A. Blythe, M. R. Evans

The Kardar-Parisi-Zhang (KPZ) equation is accepted as a generic description of interfacial growth. In several recent studies, however, values of the roughness exponent alpha have been reported that are significantly less than that associated with the KPZ equation. A feature common to these studies is the presence of holes (bubbles and overhangs) in the bulk

David Eisenbud, Gunnar Floystad, Frank-Olaf Schreyer

In this paper we study the Bernstein-Gel'fand-Gel'fand (BGG) correspondence linking sheaves on a projective space to graded modules over an exterior algebra. We give an explicit construction of a Beilinson monad for a sheaf on projective space. The explicitness allows us to to prove two conjectures about the morphisms in the monad. We also construct

J. Layssac, F. M. Renard

We compute the leading logarithms electroweak contributions to gamma gamma to f f(bar) processes in SM and MSSM. Several interesting properties are pointed out, such as the importance of the angular dependent terms, of the Yukawa terms, and especially of the $\tan^2β$ dependence in the SUSY contributions. These properties are complementary to those found in

Seiji Terashima, Tadaoki Uesugi

In this paper we extend the boundary string field theory action for a non-BPS D-brane to the one including the target space fermions and the nonlinear supersymmetry with 32 supercharges up to some order. This is based on the idea that the vacuum with a non-BPS D-brane belongs to the spontaneously broken phase of the supersymmetry. As a result, we find that t

D. Gurevich, R. Leclercq, P. Saponov

With any even Hecke symmetry R (that is a Hecke type solution of the Yang-Baxter equation) we associate a quasitensor category. We formulate a condition on R implying that the constructed category is rigid and its commutativity isomorphisms R_{U,V} are natural. We show that this condition leads to rescaling of the initial Hecke symmetry. We suggest a new way

Partha Ghose, Manoj K. Samal

Examples are worked out using a new equation proposed in the previous paper to show that it has new physical predictions for mesoscopic systems.

Naoki Yoshida, Ravi K. Sheth, Antonaldo Diaferio

We use numerical simulations of a (480 Mpc/h)^3 volume to show that the distribution of peak heights in maps of the temperature fluctuations from the kinematic and thermal Sunyaev-Zeldovich effects will be highly non-Gaussian, and very different from the peak height distribution of a Gaussian random field. We then show that it is a good approximation to assu

Partha Ghose

In spite of its popularity, it has not been possible to vindicate the conventional wisdom that classical mechanics is a limiting case of quantum mechanics. The purpose of the present paper is to offer an alternative formulation of classical mechanics which provides a continuous transition to quantum mechanics via environment-induced decoherence.

Oscar Loaiza-Brito, Angel M. Uranga

We describe the fate of the Type I non-BPS D7-brane, which is tachyonic but carries a non-trivial K-theory $\IZ_2$ charge. It decays to topologically non-trivial gauge field configurations on the background D9-branes. In the uncompactified theory the decay proceeds to infinity, while with a transverse torus the decay reaches a final state, a toron gauge conf

Michael Köhl, Theodor W. Hänsch, Tilman Esslinger

We report on the measurement of the temporal coherence of an atom laser beam extracted from a $^{87}$Rb Bose-Einstein condensate. Reflecting the beam from a potential barrier creates a standing matter wave structure. From the contrast of this interference pattern, observed by magnetic resonance imaging, we have deduced an energy width of the atom laser beam

Philippe Di Francesco, Emmanuel Guitter

We investigate models of (1+d)-D Lorentzian semi-random lattices with one random (space-like) direction and d regular (time-like) ones. We prove a general inversion formula expressing the partition function of these models as the inverse of that of hard objects in d dimensions. This allows for an exact solution of a variety of new models including critical a

M. Tohyama, A. S. Umar

The strength functions of isovector dipole resonances in the even oxygen isotopes $^{18\sim24}$O are calculated by using an extended version of the time-dependent Hartree-Fock theory known as the time-dependent density-matrix theory (TDDM). The results are compared with recent experimental data and also with a shell-model calculation. It is found that the ob

Nobuhiro Maekawa

We propose an attractive scenario of grand unified theories in which doublet-triplet splitting is beautifully realized in SO(10) unification using Dimopoulos-Wilczek mechanism. The anomalous U(1)_A gauge symmetry plays essential roles in the doublet-triplet splitting mechanism. It is interesting that the anomalous U(1)_A charges determine the unification sca

Hooman Davoudiasl, Thomas G. Rizzo

A general prediction of the 5-d Randall-Sundrum (RS) hierarchy model is the emergence of spin-2 Kaluza Klein (KK) gravitons with weak scale masses and couplings. The lowest order effective theory of the RS model is given by 5-d Einstein gravity which uniquely fixes the self-interactions of gravitons. We demonstrate that large numbers of light KK resonances c

Hubert de Guise, Barry C. Sanders, Stephen D. Bartlett, Weiping Zhang

An interferometric scheme to study Abelian geometric phase shift over the manifold SU(N)/SU(N-1) is presented.

Christian Kurtsiefer, Patrick Zarda, Sonja Mayer, Harald Weinfurter

Silicon avalanche photodiodes are the most sensitive photodetectors in the visible to near infrared region. However, when they are used for single photon detection in a Geiger mode, they are known to emit light on the controlled breakdown used to detect a photoelectron. This fluorescence light might have serious impacts on experimental applications like quan

Yan Song Li, Bei Zeng, Xiao Shu Liu, Gui Lu Long

The definition of entanglement in identical-particle system is introduced. The separability criterion in two-identical particle system is given. The physical meaning of the definition is analysed. Applications to two-boson and two-fermion systems are made. It is found new entanglement and correlation phenomena in identical-boson systems exist, and they may h

M. Ruzzi, D. Galetti

In this work we will advance farther along a line previously developed concerning our proposal of a time interval operator, on finite dimensional spaces. The time interval operator is Hermitian, and its eigenvalues are time values with a precise and interesting role on the dynamics. With the help of the Discrete Phase Space Formalism (DPSF) previously develo

V. P. Oleinik, Yu. C. Borimsky, Yu. D. Arepjev

The phenomenon of local dynamical inhomogeneity of time is predicted, which implies that the course of time along the trajectory of motion of a particle in the inertial reference frames moving relative to each other depends on the state of motion of the particle under the influence of a force field. As is seen from the results obtained, the ability to influe

Miroslav Sukenik, Jozef Sima

The present contribution documents the harmony of postulates and conclusions of Wheeler-Feynman absorber theory and the model of Expansive Nondecelerative Universe. A relationship connecting advanced electromagnetic waves and gravitational field quanta is rationalized.

Hong Qian

An analysis on the discrete versus continuous views of kinetics of macromolecules is presented. It is shown that the discrete approach traditional to biochemistry is insufficient for understanding the dynamics of protein molecules in aqueous solution. A continous view based on the Brownian dynamics in energy landscape offers a more comprehensive description

A. Loinger

Through an analysis and a generalization of a profound Fock's treatment, I make conspicuous the physically essential role of those functions of the polar radial coordinate for which the expressions of the spacetime interval are everywhere regular for all values of the above coordinate.

G. Nimtz, A. Haibel

The paper elucidates the physical basis of experimental results on superluminal signal velocity. It will be made plausible that superluminal signals do not violate the principle of causality but they can shorten the luminal vacuum time span between cause and effect. This amazing behaviour is based on the property that any physical signal has a finite duratio

Steven J. Ruuth, Seth Putterman, Barry Merriman

Sonoluminescence is the phenomena of light emission from a collapsing gas bubble in a liquid. Theoretical explanations of this extreme energy focusing are controversial and difficult to validate experimentally. We propose to use molecular dynamics simulations of the collapsing gas bubble to clarify the energy focusing mechanism, and provide insight into the

E. A. Curtis, C. W. Oates, L. Hollberg

We present a cooling method that should be generally applicable to atoms with narrow optical transitions. This technique uses velocity-selective pulses to drive atoms towards a zero-velocity dark state and then quenches the excited state to increase the cooling rate. We demonstrate this technique of quenched narrow-line cooling by reducing the 1-D temperatur

Claudio R. Mirasso, Miroslav Kolesik, Marcelo Matus, J. K. White

Dynamics of coupled semiconductor lasers is investigated by numerical simulations. A realistic laser simulation engine is used to study the synchronization and dynamical regime in two mutually coupled Fabry-Perot and/or DFB lasers. Both, single- and multi-mode operation regimes are studied with emphasis on the role of the multiple laser-cavity modes. Our fin

Norbert Feist

There is no aberration of terrestrial sources, because the lightvector has an inertial component. A new analysis of the Michelson Morley experiment shows: Light propagates anisotropically relative to a moving system, dependent on the velocity and the angle between the velocity and the direction of motion. The two way (back and forth) velocity is isotropic, b

Norbert Feist

There is no aberration of terrestrial sources, because the light-vector has an inertial component. A new analysis of the Michelson Morley experiment shows: Light propagates anisotropically relative to a moving system, dependent on the velocity and the angle between the velocity and the direction of motion. The two way (back and forth) velocity is isotropic,

V. A. Kuzmin, T. V. Tetereva, K. Junker, A. A. Ovchinnikova

Total Ordinary Muon Capture (OMC) rates are calculated on the basis of the Quasiparticle Random Phase Approximation for several spherical nuclei from 90^Zr to 208^Pb. It is shown that total OMC rates calculated with the free value of the axial-vector coupling constant g_A agree well with the experimental data for medium-size nuclei and exceed considerably th

Spencer Klein

We report the first observation of the reactions $Au + Au \to Au + Au + ρ^0$ and $Au + Au \to Au^* + Au^* + ρ^0$ with the STAR detector. The $ρ$ are produced at small perpendicular momentum, as expected if they couple coherently to both nuclei. We discuss models of vector meson production and the correlation with nuclear breakup, and present a fundamental te

V. Steinberg, R. Sütterlin, A. V. Ivlev, G. Morfill

It is shown experimentally that vertical pairing of two identical microspheres suspended in the sheath of a radio-frequency (rf) discharge at low gas pressures (a few Pa), appears at a well defined instability threshold of the rf power. The transition is reversible, but with significant hysteresis on the second stage. A simple model, which uses measured micr

J. M. Buldu, J. Garcia-Ojalvo, Claudio R. Mirasso, M. C. Torrent

Coherence resonance occurring in semiconductor lasers with optical feedback is studied via the Lang-Kobayashi model with external non-white noise in the pumping current. The temporal correlation and the amplitude of the noise have a highly relevant influence in the system, leading to an optimal coherent response for suitable values of both the noise amplitud

A. G. Ramm

A version of the projection method for solving the scattering problem for acoustic and electromagnetic waves is proposed and shown to be more efficient numerically than the earlier ones because the corresponding matrix is not ill-conditioned.

S. V. Koshkin, A. G. Ramm

The inverse problem of finding the coefficient $\g$ in the equation $\dot{u}=A(t)u+\g(t)u+f(t)$ from the extra data of the form $ϕ(t)=u(t),w$ is studied. The problem is reduced to a Volterra equation of the second kind. Applications are given to parabolic equations with second order differential operators.

Srilal Krishnan

The study of different types of ideals in non self-adjoint operator algebras has been a topic of recent research. This study focuses on principal ideals in subalgebras of groupoid C*-algebras. An ideal is said to be principal if it is generated by a single element of the algebra. We look at subalgebras of r-discrete principal groupoid C*-algebras and prove t

Sung Ho Wang

Let $Z \to Y^{2n+1}$ be the bundle of Legendrian $n$-planes over a contact manifold $Y$. We consider a foliation of $Z$ by canonical lifts of Legendrian submanifolds, called \emph{Legendrian submanifold path geometry}, whose flat model is \[ Sp(n+1, R) \to RP^{2n+1}. \] The equivalence problem provides an $sp(n+1, R)$ valued Cartan connection form that captu

Lay Nam Chang, Chopin Soo

Regularization of quantum field theories introduces a mass scale which breaks axial rotational and scaling invariances. We demonstrate from first principles that axial torsion and torsion trace modes have non-transverse vacuum polarization tensors, and become massive as a result. The underlying reasons are similar to those responsible for the Adler-Bell-Jack

Hsin-Chia Cheng, Christopher T. Hill, Stefan Pokorski, Jing Wang

We construct the manifestly gauge invariant effective Lagrangian in 3+1 dimensions describing the Standard Model in 4+1 dimensions, following the transverse lattice technique. We incorporate split generation fermions and we explore naturalness for two Higgs configurations: a universal Higgs VEV, common to each transverse brane, and a local Higgs VEV centered

S. Fedoruk, V. G. Zima

We construct the manifestly Lorentz-invariant twistorial formulation of N=1 D=4 superparticle with tensorial central charges which describes massive and massless cases in a uniform manner. The tensorial central charges are realized in terms of even spinor variables and central charge coordinates. The full analysis of the number of conserved supersymmetries h

Panagiota Kanti, Richard Madden, Keith A. Olive

We consider a 6D space-time which is periodic in one of the extra dimensions and compact in the other. The periodic direction is defined by two 4-brane boundaries. Both static and non-static exact solutions, in which the internal spacetime has constant radius of curvature, are derived. In the case of static solutions, the brane tensions must be tuned as in t

S. Mignemi

We show how the motion of a charged particle near the horizon of an extreme Reissner-Nordstrom black hole can lead to different forms of conformal mechanics, depending on the choice of the time coordinate.

Parampreet Singh, Naresh Dadhich

We show that for non-conformally flat bulk spacetime, there exist no bound modes for zero mass graviton on the 3-brane. The brane world model is therefore unstable for the bulk spacetime being different from the conformally flat anti - de Sitter space.

Andreas Gustavsson, Mans Henningson

We construct a BPS-saturated representation of the six-dimensional (2, 0) algebra with a certain non-zero value of the `central' charge. This representation is naturally carried by strings with internal degrees of freedom rather than by point particles. Upon compactification on a circle, it reduces to a massive vector multiplet in five dimensions. We also co

L. K. Hadjiivanov, Ya. S. Stanev, I. T. Todorov

Dynamical R-matrix relations are derived for the group-valued chiral vertex operators in the SU(n) WZNW model from the KZ equation for a general four-point function including two step operators. They fit the exchange relations for the U_q(sl_n) covariant quantum matrix derived previously by solving the dynamical Yang-Baxter equation. As a byproduct, we exten

D. S. Irvine, M. E. Carrington, G. Kunstatter, D. Pickering

We investigate the two-loop effective potential for both minimally and non-minimally coupled Maxwell-Chern-Simons theories. The non-minimal gauge interaction represents the magnetic moment interaction between a charged scalar and the electromagnetic field. In a previous paper we have shown that the two loop effective potential for this model is renormalizabl

M. Awramik, M. Jezabek

Longitudinal polarization of the top quark, averaged over the production angle, is discussed for the top quark produced in e+e- annihilation near its production threshold. It is demonstrated that Coulomb type corrections and rescattering corrections are important. They change considerably measurable quantities and should be taken into account in phenomenolog

Yu. S. Surovtsev, D. Krupa, M. Nagy

A simultaneous analysis (in the model-independent approach) of the $ππ$ scattering (from the threshold to 1.9 GeV) and of the $ππ\to K\overline{K}$ process (from the threshold to $\sim$ 1.46 GeV) is carried out in channel with $I^GJ^{PC}=0^+0^{++}$. The existence of the $f_0(665)$ state with properies of the $σ$-meson is proved. An indication for the gluebal

P. Grabmayr, A. J. Buchmann

Recent data allow a new parametrization of the neutron charge form factor G_En. A parameter-free quark model relation between G_En and the N->Delta quadrupole form factor is used to predict the latter from the G_En data. In particular, the neutron charge radius is related to N->Delta quadrupole moment, while the fourth moment of G_En connects to the N->Delta

Changhao Jin

We discuss an improved theoretical description of the semi-inclusive B meson decays $B\to K(K^*)X$. The decay distributions are calculated. Their branching ratios are found to be appreciable. The CP asymmetries in the neutral B modes $\bar{B^0}\to K^-(K^{*-})X$ are sizable. An observation of direct CP violation and a measurement of $γ$ may come from these ne

Yoshimasa Kurihara, Masaaki Kuroda, Dieter Schildknecht

The results on e+e- --> W+W- --> 4f(+gamma) obtained by different groups are compared with each other. Differences in the results for the total cross section of up to about 0.6% are traced back to different ways of implementing the double-pole approximation.

Hsin-Chia Cheng, David Elazzar Kaplan

The axion solution to the strong CP problem requires an anomalous global U(1) symmetry. We show that the existence of such a symmetry is a natural consequence of an extra dimension in which a gauged U(1) is spontaneously broken on one of two branes, leaving an accidental global symmetry on the other brane. Depending on where the standard model matter lives,

D. T. Son, M. A. Stephanov, A. R. Zhitnitsky

A Coulomb gas representation of dense-matter QCD is derived from a dual transformation of the low-energy effective Lagrangian. The point-like charges Q=+1,-1 of the gas are identified with the instantons and anti-instantons of such topological charges. An instanton repels another instanton with the same force as it attracts an anti-instanton, in contrast to

ALEPH Collaboration

The polarisation of $τ$'s produced in Z decay is measured using 160 pb$^{-1}$ of data accumulated at LEP by the ALEPH detector between 1990 and 1995. The variation of the polarisation with polar angle yields the two parameters ${\cal A}_e = 0.1504 \pm 0.0068 $ and ${\cal A}_τ = 0.1451 \pm 0.0059$ which are consistent with the hypothesis of $e$-$τ$ univer

Claus Lämmerzahl, Hansjörg Dittus, Achim Peters, Stephan Schiller

A new satellite based test of Special and General Relativity is proposed. For the Michelson-Morley experiment we expect an improvement of at least three orders of magnitude, and for the Kennedy-Thorndike experiment an improvement of more than one order of magnitude. Furthermore, an improvement by two orders of the test of the universality of the gravitationa

A. D. Alexeev, K. A. Bronnikov, N. I. Kolosnitsyn, M. Yu. Konstantinov

We describe some new estimates concerning the recently proposed SEE (Satellite Energy Exchange) experiment for measuring the gravitational interaction parameters in space. The experiment entails precision tracking of the relative motion of two test bodies (a heavy "Shepherd", and a light "Particle") on board a drag-free space capsule. The new

K. E. Nagaev

A cross-shaped diffusive system with two superconducting and two normal electrodes is considered. A voltage $eV < Δ$ is applied between the normal leads. Even in the absence of average current through the superconducting electrodes their presence increases the shot noise at the normal electrodes and doubles it in the case of a strong coupling to the supercon

J. M. Yanez, M. I. Molina, D. C. Mattis

We calculate thermodynamic properties of a disordered model insulator, starting from the ideal simple-cubic lattice ($g = 0$) and increasing the disorder parameter $g$ to $\gg 1/2$. As in the earlier Einstein- and Debye- approximations, the ground state energy is discontinuous at $g_{c} = 1/2$. For $g<g_{c}$ the low-T heat-capacity $C \sim T^{3}$ whereas for

Angel J. Garcia-Adeva, David L. Huber

The effect of site dilution by non magnetic impurities on the susceptibility of geometrically frustrated antiferromagnets (kagome and pyrochlore lattices) is discussed in the framework of the Generalized Constant Coupling model, for both classical and quantum Heisenberg spins. For the classical diluted pyrochlore lattice, excellent agreement is found when co

S. Gruss, G. Fuchs, G. Krabbes, P. Verges

Improved trapped fields are reported for bulk melt-textured YBa2Cu3O7-x (YBCO) material in the temperature range between 20 K and 50 K. Trapped fields up to 12.2 T were obtained at 22 K on the surface of single YBCO disks (with Ag and Zn additions). In YBCO mini-magnets, maximum trapped fields of 16 T (at 24 K) and of 11.2 T (at 47 K) were achieved using (Zn

Marc Ruhlander, Peter Markos, C. M. Soukoulis

The probability distribution of the conductance at the mobility edge, $p_c(g)$, in different universality classes and dimensions is investigated numerically for a variety of random systems. It is shown that $p_c(g)$ is universal for systems of given symmetry, dimensionality, and boundary conditions. An analytical form of $p_c(g)$ for small values of $g$ is d

Qing-Hu Chen, Lei-Han Tang, Peiqing Tong

We report large-scale simulations of the resistively-shunted Josephson junction array in strip geometry. As the strip width increases, the voltage first decreases following the dynamic scaling ansatz proposed by Minnhagen {\it et al.} [Phys. Rev. Lett. {\bf 74}, 3672 (1995)], and then rises towards the asymptotic value predicted by Ambegaokar {\it et al.} [P

E. del Barco, J. M. Hernandez, M. Duran, J. Tejada

In this paper we report magnetic relaxation data for antiferromagnetic alpha-Fe2O3 particles of 5 nm mean diameter in the temperature range 0.1 K to 25 K. The average spin value of these particles S=124 and the uniaxial anisotropy constant D=1.6x10^-2 K have been estimated from the experimental values of the blocking temperature and anisotropy field. The obs

J. -M. Caillol

We reconsider the density functional theory of nonuniform classical fluids from the point of view of convex analysis. From the observation that the logarithm of the grand-partition function $\log Ξ[ϕ]$ is a convex functional of the external potential $ϕ$ it is shown that the Kohn-Sham free energy ${\cal A}[ρ]$ is a convex functional of the density $ρ$. $\log

Gang Su, Masuo Suzuki

It can be shown that the bosonic degree of freedom of the tightly bound on-site electron pairs could be separated as Schwinger bosons. This is implemented by projecting the whole Hilbert space into the Hilbert subspace spanned by states of two kinds of Schwinger bosons (to be called binon and vacanon) subject to a constraint that these two kinds of bosonic q

Gang Su

Some issues concerning the question if the two-dimensional Hubbard model really show d-wave superconductivity are briefly discussed.

A. M. M. Pruisken, M. A. Baranov, I. S. Burmistrov

We report the consequences of a new interaction symmetry that protects the renormalization of the electron gas in low dimensions in general, and in the quantum Hall regime in particular. We introduce a generalized Thouless&#39; criterion for localization to include the effects of the Coulomb interaction and establish the quantization of the Hall conductance

R. Straub, S. Keil, R. Kleiner, D. Koelle

We used low-temperature scanning electron microscopy (LTSEM) for imaging quantized magnetic flux (vortices) in direct current (dc) superconducting quantum interference devices (SQUIDs) with approximately 1 micron spatial resolution at temperature T=77 K in a controllable magnetic field up to 20 microTesla. We demonstrate that LTSEM allows to image the spatia

Ute Löw, Erwin Müller-Hartmann

We discuss the phase diagram of the Shastry-Sutherland model for arbitrary spin S and derive rigorous lower and upper bounds on the phase boundaries of the dimer phase by using various versions of a variational ansatz in combination with the exact diagonalisation method.

Peter Scheidler, Walter Kob, Kurt Binder, Giorgio Parisi

We present the results of molecular dynamics computer simulations of a simple glass former close to an interface between the liquid and the frozen amorphous phase of the same material. By investigating F_s(q,z,t), the incoherent intermediate scattering function for particles that have a distance z from the wall, we show that the relaxation dynamics of the pa

A. M. Cuitino, L. Stainier, G. Wang, A. Strachan

In this paper we present a modeling approach to bridge the atomistic with macroscopic scales in crystalline materials. The methodology combines identification and modeling of the controlling unit processes at microscopic level with the direct atomistic determination of fundamental material properties. These properties are computed using a many body Force Fie

N. Ihara, S. Yoshida, K. Wada

The Cluster Variation Method (CVM) is applied to the Ishibashi model for ammonium dihydrogen phosphate ($\rm NH_{4}H_{2}PO_{4}$) of a typical hydrogen bonded anti-ferroelectric crystal. The staggered and the uniform susceptibility without hysteresis are calculated at equilibrium. On the other hand, by making use of the natural iteration method (NIM) for the

Karl E. Haisch, Elizabeth A. Lada, Charles J. Lada

We report the results of the first sensitive L-band (3.5 micron) survey of the intermediate age (2.5 - 30 Myr) clusters NGC 2264, NGC 2362 and NGC 1960. We use JHKL colors to obtain a census of the circumstellar disk fractions in each cluster. We find disk fractions of 52% +/- 10%, 12% +/- 4% and 3% +/- 3% for the three clusters respectively. Together with o

A. Misiriotis, C. C. Popescu, R. Tuffs, N. D. Kylafis

Using tools previously described and applied to the prototype galaxy NGC 891, we model the optical to far-infrared spectral energy distributions (SED) of four additional edge-on spiral galaxies, namely NGC 5907, NGC 4013, UGC 1082 and UGC 2048. Comparing the model predictions with IRAS and, where available, sub-millimeter and millimeter observations, we dete

A. J. Baker, D. Lutz, R. Genzel, L. J. Tacconi

We detect 1.2mm continuum emission from dust in the gravitationally lensed Lyman break galaxy MS 1512+36-cB58. Our detected flux is surprisingly low: relative to local starburst galaxies, cB58 appears to produce somewhat less far-IR emission than its UV reddening predicts. After comparing several different estimates of the source&#39;s dust content, we concl

K. J. Brooks, J. W. V. Storey, J. B. Whiteoak

We present results from observations of H110alpha recombination-line emission at 4.874 GHz and the related 4.8-GHz continuum emission towards the Carina Nebula using the Australia Telescope Compact Array. These data provide information on the velocity, morphology and excitation parameters of the ionized gas associated with the two bright HII regions within t

Jorge A. Combi, Gustavo E. Romero, Diego F. Torres, Brian Punsly

We present a study of the radio environment of the gamma-ray source 3EG J1828+0142. This source presents a very high variability index in its gamma emission and a steep high-energy spectral index $Γ\sim-2.8$. Large-scale radio maps at different frequencies show the presence of a shell-type non-thermal structure when the diffuse emission from the Galactic dis

Alexander E. Rosenbush

The well-known light minima of stars with the R Coronae Borealis variability are caused by the formation of an additional circumstellar dust shell, the screening shell, inside the permanent shell. Under the assumption of uniform distribution of matter in the circumstellar environment we estimated the optical thickness of the permanent gas-and-dust shell at 0

S. Silich, G. Tenorio-Tagle, C. Munoz-Tunon, L. M. Cairos

The recent history of star formation in VIIZw 403 is analyzed taking into account the dynamics of the starburst blown superbubble and the restrictions that follow from X-ray observations, and from our H$α$ data. Our results show that the starburst energizing VIIZw 403 is NOT coeval, but rather the star forming phase has lasted for more than 30Myr and at such

D. Konenkov, U. Geppert

We consider the expulsion of proton fluxoids along neutron vortices from the superfluid/superconductive core of neutron star with weak ($B<10^{10}$ G) magnetic field. The velocity of fluxoids is calculated from the balance of buoyancy, drag and crustal forces. We show, that the proton fluxoids can leave the superfluid core sliding {\it along} the neutron vor

P. Bauleo, C. Bonifazi, A. Filevich, A. Reguera

A new Air Shower Observatory has been constructed in Buenos Aires during 1999, and commissioned and set in operation in 2000. The observatory consists of an array of four water Čerenkov detectors, enclosing a geometrical area of $\sim$ 30.000 m$^{2}$, and is optimized for the observation of cosmic rays in the ``knee&#39;&#39; energy region. The array detects

Boris Dintrans

The problem of the long-period gravity modes of the Earth outer fluid core is investigated using either the subseismic or the anelastic approximation These two approximations aim at filtering out the uninteresting short-period seismic or acoustic oscillations while taking into account the density variations across the core However, they differ on the form of

Melvyn B. Davies, Steinn Sigurdsson

We consider the survivability of planetary systems in the globular cluster 47 Tucanae. We compute the cross sections for the breakup of planetary systems via encounters with single stars and binaries. We also compute the cross sections to leave planets on eccentric orbits. We find that wider planetary systems (d > 0.3 AU) are likely to be broken up in the ce

R. Toenjes, H. Schatz, K. -L. Kratz, B. Pfeiffer

We obtain age estimates for the progenitor(s) of the extremely metal-poor ([Fe/H = -2.9) halo star CS 31082-001, based on the recently reported first observation of a Uranium abundance in this (or any other) star. Age estimates are derived by application of the classical r-process model with updated nuclear physics inputs. The [U/Th] ratio yields an age of 1

S. A. Pustilnik, A. Y. Kniazev, V. A. Lipovetsky, A. V. Ugryumov

(abridged) The work studies active star formation (SF) and a possible trigger of SF bursts due to gravitational interaction. Following the study by Taylor et al. we extend the search for possible disturbing galaxies of various masses to a much larger sample of 86 BCGs from the sky region of Second Byurakan survey. The sample under study is separated by the c

A. R. King, M. B. Davies, M. J. Ward, G. Fabbiano

We investigate models for the class of ultraluminous non-nuclear X-ray sources (ULXs) seen in a number of galaxies and probably associated with star-forming regions. Models where the X-ray emission is assumed to be isotropic run into several difficulties. In particular formation of sufficient numbers of the required ultramassive black-hole X-ray binaries is

Jayaram N. Chengalur, R. Braun, M. Wieringa

We discuss Australia Telescope Compact Array (ATCA) HI 21cm data for the galaxy cluster A3128. Our observations are intentionally relatively shallow, and a blind search through our data cube yields (tentative) detections of only two galaxies, of which one is probably spurious. A3128 is part of the ESO Nearby Abell Cluster Survey (ENACS); redshifts are availa

J. R. Rizzo, J. Martin-Pintado, C. Henkel

We report the detection of the (1,1) and (2,2) metastable lines of ammonia (NH_3) in the molecular cloud associated with the Wolf--Rayet (WR) nebula NGC 2359. Besides the CO and H_2, this is the first molecule detected in the environs of a WR star. Width (3 km/s) and radial velocity (54 km/s) indicate that the NH$_3$ lines arises from the molecular cloud whi

B. C. Tiburzi, G. A. Miller

We explore skewed parton distributions for simple, model wave-functions in a truncated two-body Fock space. Consideration of non-Gaussian wave functions is our main emphasis, from which we observe the distributions are bimodal (there can be two distinct peaks) in the Fock-space diagonal overlap region (x > xi). We demonstrate that this behavior arises from c

John D. Anderson, Philip A. Laing, Eunice L. Lau, Anthony S. Liu

Our previous analyses of radio Doppler and ranging data from distant spacecraft in the solar system indicated that an apparent anomalous acceleration is acting on Pioneer 10 and 11, with a magnitude a_P ~ 8 x 10^{-8} cm/s^2, directed towards the Sun (anderson,moriond). Much effort has been expended looking for possible systematic origins of the residuals, bu

Marco A. C. Kneipp, Patrick Brockill

Starting from the bosonic part of N=2 Super QCD with a &#39;Seiberg-Witten&#39; N=2 breaking mass term, we obtain string BPS conditions for arbitrary semi-simple gauge groups. We show that the vacuum structure is compatible with a symmetry breaking scheme which allows the existence of Z_k-strings and which has Spin(10) -> SU(5) x Z_2 as a particular case. We

Walter D. Goldberger, Mark B. Wise

Field theories in the presence of branes encounter localized divergences that renormalize brane couplings. The sources of these brane-localized divergences are understood as arising either from broken translation invariance, or from short distance singularities as the brane thickness vanishes. While the former are generated only by quantum corrections, the l