June 2000 arXiv papers — page 17

A. Stolcke

A criterion for pruning parameters from N-gram backoff language models is developed, based on the relative entropy between the original and the pruned model. It is shown that the relative entropy resulting from pruning a single N-gram can be computed exactly and efficiently for backoff models. The relative entropy measure can be expressed as a relative chang

E. Shriberg, R. Bates, A. Stolcke, P. Taylor

Identifying whether an utterance is a statement, question, greeting, and so forth is integral to effective automatic understanding of natural dialog. Little is known, however, about how such dialog acts (DAs) can be automatically classified in truly natural conversation. This study asks whether current approaches, which use mainly word information, could be

M. E. Zhitomirsky, T. M. Rice, V. I. Anisimov

In this comment we point out several misleading conclusions reached by Rodriguez et al. [PRL 84, 3903 (2000) and cond-mat/0003201] about the details of the band structure in SrB_6 and their role in interpreting the high-temperature weak ferromagnetism, which develops in this material upon doping.

Aiman Al-Omari

Dimerization of a spin-half Heisenberg antiferromagnet on a square lattice is investigated for several possible dimerized configurations, some of which are shown to have lower ground state energies than the others. In particular, the lattice deformations resulting in alternate stronger and weaker couplings along both the principal axes of a square lattice ar

Matthias J. Graf, S. -K. Yip, J. A. Sauls

This paper summarizes the results of a comprehensive analysis of the thermodynamic and transport data for the superconducting phases of UPt_3. Calculations of the transverse sound attenuation as a function of temperature, frequency, polarization, and disorder are presented for the leading models of the superconducting order parameter. Measurements of the spe

Assa Auerbach, Ehud Altman

The projected SO(5) theory (pSO(5)) is used to resolve the puzzle of two distinct energy gaps in high T$_c$ Superconductor-Normal-Superconductor junctions. Counter to conventional theory of multiple Andreev reflections (MAR), the differential resistance peaks are associated with the antiferromagnetic resonance observed in neutron scattering, and not with Coo

Andrzej A. Zdziarski

Selected topics dealing with X-ray/soft gamma-ray emission from accreting black-hole sources are reviewed. The shape of soft gamma-ray spectra of Seyferts observed by OSSE can be well modelled by thermal Comptonization. A very strong correlation between the X-ray slope and the strength of Compton reflection in these sources can then be explained by thermal C

G. Alverson, L. A. Anchordoqui, G. Cooperman, V. Grinberg

{\sc top-c} (Task Oriented Parallel C) is a freely available package for parallel computing. It is designed to be easy to learn and to have good tolerance for the high latencies that are common in commodity networks of computers. It has been successfully used in a wide range of examples, providing linear speedup with the number of computers. A brief overview

D. L. Tucker, A. Oemler, Y. Hashimoto, S. A. Shectman

A ``friends-of-friends'' percolation algorithm has been used to extract a catalogue of dn/n = 80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalogue contains 1495 groups and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has been derived by culling groups from the full sample

F. N. Owen, M. J. Ledlow, J. A. Eilek, N. E. Kassim

Extended radio emission and its relation to parent galaxy properties is briefly reviewed. Our current understanding of the relation between absolute radio and optical luminosity, radio morphology and linear size is discussed. The impact of radio jets on dense cluster cores is discussed using M87 as an example. Finally, the relation of AGN's to star-burst

Andrzej A. Zdziarski, Juri Poutanen, W. Neil Johnson

We present a summary of spectra of Seyfert galaxies observed by the OSSE detector aboard Compton Gamma Ray Observatory. We obtain average spectra of Seyferts of type 1 and 2, and find they are well fitted by thermal Comptonization. We present detailed parameter ranges for the plasma temperature and the Compton parameter in the case of spherical and slab geom

D. Burstein

The Institute for Science Information (ISI) has generated two lists of citation information for astronomers that are uniquely restricted both as to the years surveyed for the cited papers, and the years surveyed for the citing papers. The main list gives citation data for 62,813 physicists and astronomers whose journal papers were cited 100 times or more fro

Andrzej A. Zdziarski

I review radiative processes responsible for X-ray emission in the hard (low) and soft (high) spectral states of black-hole binaries. The main process in the hard state appears to be thermal Comptonization (in a hot plasma) of blackbody photons emitted by a cold disk. This is supported by correlations between the spectral index, the strength of Compton refle

Ovidiu Lipan, Constantin Rasinariu

The Darboux transformation applied recurrently on a Schroedinger operator generates what is called a {\em dressing chain}, or from a different point of view, a set of supersymmetric shape invariant potentials. The finite-gap potential theory is a special case of the chain. For the finite-gap case, the equations of the chain can be expressed as a time evoluti

J. P. Rodriguez

The mixed phase of extremely type-II layered superconductors in perpendicular magnetic field is studied theoretically via the layered XY model with uniform frustration. A partial duality analysis is carried out in the weak-coupling limit. It consistently accounts for both intra-layer (pancake) and inter-layer (Josephson) vortex excitations. The main conclusi

W. Yuan, M. Matsuoka, T. Wang, S. Ueno

We report the discovery of an unambiguous, substantial low-energy cutoff in the broad band X-ray spectrum of the radio quasar RXJ1028.6-0844 at a redshift of 4.276 obtained with the ASCA satellite, which we preferably explained as indication of excess X-ray absorption. The equivalent hydrogen column density of the absorbing matter, depending on the redshift

N. Okamura, M. Tanimoto

We have studied implications of the generic lopsided mass matrix of the charged leptons by taking the SU(5) GUT relation in the nearest-neighbor interaction (NNI) basis. We have found four interesting relations among the lepton mixings and the quark ones, which are independent of details of the model. These relations are discussed by using the experimental d

G. Cvetic, R. Koegerler

A renormalization-scale-invariant generalization of the diagonal Padé approximants (dPA), developed previously, is extended so that it becomes renormalization-scheme-invariant as well. We do this explicitly when two terms beyond the leading order (NNLO, $\sim α_s^3$) are known in the truncated perturbation series (TPS). At first, the scheme dependence shows

H. Davoudiasl, J. L. Hewett, T. G. Rizzo

The (g-2) of the muon is well known to be an important model building constraint on theories beyond the Standard Model. In this paper, we examine the contributions to $(g-2)_μ$ arising in the Randall-Sundrum model of localized gravity for the case where the Standard Model gauge fields and fermions are both in the bulk. Using the current experimental world av

Arne Brataas, Yu. V. Nazarov, G. E. W. Bauer

A theory of spin-transport in hybrid normal metal - ferromagnetic electronic circuits is developed, taking into account non-collinear spin-accumulation. Spin-transport through resistive elements is described by 4 conductance parameters. Microscopic expression for these conductances are derived in terms of scattering matrices and explicitly calculated for sim

Antoine Suarez

It is argued that: 1) Quantum Mechanics implies the preferred frame also because of the collapse delayed at detection, 2) forthcoming experiments with moving beam-splitters will allow us to decide between Preferred Frame and Multisimultaneity, and 3) if the Preferred Frame prevails, superluminal communication is in principle possible.

Roberto Romo, Jorge Villavicencio

The buildup process of the probability density inside the quantum well of a double-barrier resonant structure is studied by considering the analytic solution of the time dependent Schrödinger equation with the initial condition of a cutoff plane wave. For one level systems at resonance condition we show that the buildup of the probability density obeys a sim

Yi-Xin Chen, Dong Yang

Entanglement shared between two seperated parties could not be increased without transmitting quantum system. We suggest the project to gain entanglement shared between Alice and Bob by transmitting quantum system and a nem scheme to achieve efficient rate of entanglement. It is proven that under any local operations and communicating classically, to transmi

A. Mary Selvam, A. S. R. Murty

A scale invariant, selfsimilar atmospheric eddy continuum exists in the planetary atmospheric boundary layer spanning several orders of magnitude in scales and gives rise to the observed fractal geometry for the global cloud cover pattern. The global weather systems are manifestations of the unified atmospheric eddy continuum with inherent mutual global-loca

Valerio Faraoni

Many pedagogical introductions of cosmological inflation are effective due to the simplicity of the relevant equations. Here an analytic solution of the cosmological equations is presented and used as an example to discuss fundamental aspects of the inflationary paradigm.

L. Ya. Kobelev

In the space and the time with a fractional dimensions the Lorents transformations fulfill only as a good approach and become exact only when dimensions are integer. So the principle of relativity (it is exact when dimensions are integer) may be treated also as a good approximation and may remain valid (but modified) in case of small fractional corrections t

N. F. Allard, J. Kielkopf, I. Drira, P. Schmelcher

We present a theoretical profile of the Lyman Beta line of atomic hydrogen perturbed by collisions with neutral hydrogen atoms and protons. We use a general unified theory in which the electric dipole moment varies during a collision. A collision-induced satellite appears on Lyman Beta, correlated to the B''\barB 1Sigma+u - X 1Sigma+g asymptotically

A. V. Avdeenkov, S. P. Kamerdzhiev

A system of equations is obtained for the Cooper gap in nuclei. The system takes two mechanisms of superfluidity into account in an approximation quadratic in the phonon- production amplitude : a Bardeen- Cooper- Schrieffer (BCS) type mechanism and a quasiparticle- phonon mechanism. These equations are solved for 120 Sn in a realistic approximation. If the s

T. Barnes, E. S. Swanson, C. Y. Wong

In this contribution we summarize experimental information and theoretical results for the dissociation cross sections of charmonium by light hadrons. Theoretical predictions for these RHIC-related processes differ by orders of magnitude over the physically relevant energy range. The results found by the author and collaborators using a constituent interchan

Vassil M. Vassilev, Peter A. Djondjorov

In the present paper, a class of partial differential equations related to various plate and rod problems is studied by Lie transformation group methods. A system of equations determining the generators of the admitted point Lie groups (symmetries) is derived. A general statement of the associated group-classification problem is given. A simple intrinsic rel

Jose F. Carinena, Arturo Ramos

The concept of partnership of potentials is studied in detail and in particular the non-uniqueness due to the ambiguity in the election of the factorization energy and in the choice of the solution of certain Riccati equation. We generate new factorizations from old ones using invariance under parameter transformations. The theory is illustrated with some ex

Vladimir Uspenskij

For every topological group G one can define the universal minimal compact G-space X=M_G characterized by the following properties: (1) X has no proper closed G-invariant subsets; (2) for every compact G-space Y there exists a G-map X-->Y. If G is the group of all orientation-preserving homeomorphisms of the circle S^1, then M_G can be identified with S^1 (V

N. C. A. da Costa, F. A. Doria

We formulate the $P<NP$ hypothesis in the case of the satisfiability problem as a $Π^0_2$ sentence, out of which we can construct a partial recursive function $f_{\neg A}$ so that $f_{\neg A}$ is total if and only if $P < NP$. We then show that if $f_{\neg A}$ is total, then it isn&#39;t ${\cal T}$--provably total (where ${\cal T}$ is a fragment of ZFC that

Dmitri Nikshych, Vladimir Turaev, Leonid Vainerman

We use categories of representations of finite dimensional quantum groupoids (weak Hopf algebras) to construct ribbon and modular categories that give rise to invariants of knots and 3-manifolds.

Dmitri Nikshych, Leonid Vainerman

We give a survey of the theory of finite quantum groupoids (weak Hopf algebras), including foundations of the theory and applications to finite depth subfactors, dynamical deformations of quantum groups, and invariants of knots and 3-manifolds.

T. Matsuki, M. Shiotani, R. W. Haymaker

Assuming dynamical spontaneous breakdown of chiral symmetry for massless gauge theory without scalar fields, we present a method how to construct an effective action of the dynamical Nambu-Goldstone bosons and elemetary fermions by using auxiliary fields. Here dynamical particles are asssumed to be composed of elementary fermions. Various quantities includin

E. Witten

It has been shown recently that by turning on a large noncommutativity parameter, the description of tachyon condensation in string theory can be drastically simplified. We reconsider these issues from the standpoint of string field theory, showing that, from this point of view, the key fact is that in the limit of a large B-field, the string field algebra f

Kevin Cahill

Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle x_nu characterizes the kind of the neutrinos, with x_nu = 0 for Dirac neutrinos and x_nu = pi/2 for Majorana neutrinos. If x_nu = 0, then baryon-minus-lepton number is conserved. When x_nu is

A. D. Dolgov

New nucleosynthesis bounds on the oscillation parameters of active neutrinos mixed with a sterile one are derived for the non-resonant case. The controversy in the literature whether to use the annihilation rate or the total reaction rate for the estimates of sterile neutrino production is resolved in favor of the annihilation rate. In contrast to previous p

I. P. Ivanov, N. N. Nikolaev

In the framework of the $κ$-factorization approach and on the basis of recently determined DGSF, we calculated the production rates of ground and excited (2S and D wave) states of vector mesons and investigated their various kinematical and spin dependencies. We also addressed the issue of S/D wave mixing in quarkonia.

I. P. Ivanov, N. N. Nikolaev

We present the first experiment-based parameterization of differential gluon structure function, which is called upon in many applications. We compare $κ$-factorization and DGLAP approaches and analyze properties of DGSF, with special emphasis on soft-to-hard/hard-to-soft diffusion.

Parvez Anandam

We analytically evaluate in the leading logarithm approximation the differential cross section for e^+ e^- -> e^+ ν_e \bar{u} d. We compare our order α^4 α_s^0 leading-log result to the order α^4 α_s^0 exact result obtained from the GRC4F Monte Carlo program. Finally we use the Gluck, Reya, Schienbien distribution of partons in a virtual photon, which incorp

A. Shariati, M. Khorrami

We address the old question of whether or not a uniformly accelerated charged particle radiates, and consequently, if weak equivalence principle is violated by electrodynamics. We show that radiation has different meanings; some absolute, some relative. Detecting photons or electromagnetic waves is NOT absolute, it depends both on the electromagnetic field a

Hans Ringstrom

We consider the asymptotic behaviour of spatially homogeneous spacetimes of Bianchi type IX close to the singularity (we also consider some of the other Bianchi types, e. g. Bianchi VIII in the stiff fluid case). The matter content is assumed to be an orthogonal perfect fluid with linear equation of state and zero cosmological constant. In terms of the varia

Piotr Bizoń, Arthur Wasserman

We investigate spherically symmetric continuously self-similar (CSS) solutions in the SU(2) sigma model coupled to gravity. Using mixed numerical and analytical methods, we provide evidence for the existence (for small coupling) of a countable family of regular CSS solutions. This fact is argued to have important implications for the ongoing studies of black

A. Loinger

The correct characterization of the concept of mass point in general relativity is a straightforward consequence of the original form of solution given by Schwarzschild to the problem of the Einstein field of a material point.

Ahmed Helmy

With the introduction of a newer generation of wireless devices and technologies, the need for an efficient architecture for IP mobility is becoming more apparent. Several architectures have been proposed to support IP mobility. Most studies, however, show that current architectures, in general, fall short from satisfying the performance requirements for wir

Alexei Vazquez

A population of heterogenous agents compeeting through a minority rule is investigated. Agents which frequently loose are selected for evolution by changing their strategies. The stationary composition of the population resulting for this self-organization process is computed analytically. Results are compared with numerical simulations of two different mino

A. A. Aligia

We study a Heisenberg chain with nearest-neighbor (NN) J1 and next-NN J2 exchange interactions with anisotropies Delta_1 and Delta_2 respectively. We investigate by analytical and numerical methods the region of parameters for which there is a jump in the magnetization M as a function of magnetic field B. Some materials with edge sharing CuO polihedra are ca

R. Saniz, S. P. Apell

We study the origin of the structure in the spin-polarized electron energy loss spectroscopy (SPEELS) spectra of ferromagnetic crystals. Our study is based on a 3d tight-binding Fe model, with constant onsite Coulomb repulsion U between electrons of opposite spin. We find it is not the total density of Stoner states as a function of energy loss which determi

J. Huang, N. Eradat, M. E. Raikh, Z. V. Vardeny

We studied coherent backscattering (CBS) of light from opal photonic crystals in air at different incident inclination angles, wavelengths and along various [hkl] directions inside the opals. Similar to previously obtained CBS cones from various random media, we found that when Bragg condition with the incident light beam is not met then the CBS cones from o

F. N. Owen, J. a Eilek, N. E. Kassim

We report new radio imaging of the large scale radio structure of M87 with the VLA at 90 cm. These new images show the complex structure of the radio emission more clearly than previous attempts, some of which date back to the 1940&#39;s. The images suggest that the outward flow from the M87 nucleus extends well beyond the 2 kpc jet. Two ``bubbles&#39;&#39;

K. J. Borkowski, J. Rho, S. P. Reynolds, K. K. Dyer

Supernova remnants may exhibit both thermal and nonthermal X-ray emission. Such remnants can be distinguished by the weakness of their X-ray lines, because of the presence of a strong nonthermal X-ray continuum. RCW 86 is a remnant with weak lines, resulting in low and peculiar abundances when thermal models alone are used to interpret its X-ray spectrum. Th

A. S. Wilson, P. L. Shopbell, Chris Simpson, T. Storchi-Bergmann

We present an HST imaging study of the nearby (4 Mpc distant) Circinus galaxy, which contains the nearest type 2 Seyfert nucleus and prominent circumnuclear star formation. Images have been obtained in the [OIII]$λ$5007, H$α$ and H$_2$ v=1--0 S(1) emission lines, and in the green (5470 Å), red (8140 Å) and near infrared (2.04 and 2.15 $μ$m) continua. An imag

E. García, A. Hernández-Galeana, D. Jaramillo, W. A. Ponce

In a model with a gauge group $G_{SM}\otimes U(1)_X$, where $G_{SM} \equiv SU(3)_C \otimes SU(2)_L \otimes U(1)_Y$ is the standard model gauge group and $U(1)_X$ is a horizontal local gauge symmetry, we propose a radiative generation of the spectrum of quark masses and mixing angles. The assignment of horizontal charges is such that at tree level only the th

Gaston Giribet, Carmen Nunez

The near boundary limit of string theory in AdS_3 is analysed using the Wakimoto free field representation of SL(2,R). The theory is considered as a direct product of the SL(2,R)/U(1) coset and a free boson. Correlation functions are constructed generalizing to the non-compact case the integral representation of conformal blocks introduced by Dotsenko in the

Semyon Pol&#39;shin

We construct a system of coherent states for the hydrogen atom that is expressed in terms of elementary functions. Unlike to the previous attempts in this direction, this system possesses the properties equivalent to the most of those for the harmonic oscillator, with modifications due to the character of the problem.

Jens G Jensen, Ruediger Schack

We describe an algorithm for converting one bipartite quantum state into another using only local operations and classical communication, which is much simpler than the original algorithm given by Nielsen [Phys. Rev. Lett. 83, 436 (1999)]. Our algorithm uses only a single measurement by one of the parties, followed by local unitary operations which are permu

Simon Portegies Zwart, Tomonori Totani

We present an internal shock model with external characteristics for explaining the complicated light curves of gamma-ray bursts. Shocks produce gamma-rays in the interaction between a precessing beam of relativistic particles and the interstellar medium. Each time the particle beam passes the same line of sight with the observer the inter stellar medium is

John F. Donoghue

One way that an anthropic selection mechanism may be manifest in a physical theory involves multiple domains in the universe with different values of the physical parameters. If this mechanism is to be relevant for understanding the small observed value of the cosmological constant, it may involve a mechanism by which some contributions to the cosmological c

U. D. Jentschura, G. Soff

The conformal mapping of the Borel plane can be utilized for the analytic continuation of the Borel transform to the entire positive real semi-axis and is thus helpful in the resummation of divergent perturbation series in quantum field theory. We observe that the rate of convergence can be improved by the application of Padé approximants to the Borel transf

Kenneth F. Nicholson

Given the dimensions (including thickness) of an axisymmetric galaxy, Newton&#39;s law is used in integral form to find the density distributions required to match a wide range of orbital speed profiles. Newton&#39;s law is not modified and no dark matter halos are required. The speed distributiions can have extreme shapes if they are reasonably smooth. Seve

D0 Collaboration

We present a quasi-model-independent search for the physics responsible for electroweak symmetry breaking. We define final states to be studied, and construct a rule that identifies a set of relevant variables for any particular final state. A new algorithm (&#34;Sleuth&#34;) searches for regions of excess in those variables and quantifies the significance o

A. Merloni, T. Di Matteo, A. C. Fabian

The simultaneous presence of a strong quasi periodic oscillation of period of about 10 seconds in the optical and X-ray lightcurves of the X-ray transient XTE J1118+480 suggests that a significant fraction of the optical flux originates from the inner part of the accretion flow, where most of the X-rays are produced. We present a model of magnetic flares in

A. A. Grib, Yu. V. Pavlov

The model of creation of observable particles and particles of the dark matter, considered to be superheavy particles, due to particle creation by the gravitational field of the Friedmann model of the early Universe is given. Estimates on the parameters of the model leading to observable values of the baryon number of the Universe and the dark matter density

R. Mélin

This preprint has been merged with cond-mat/0005361

Salah Hamieh, Jean Letessier, Johann Rafelski

Lattice-QCD results provide an opportunity to model, and extrapolate to finite baryon density, the properties of the quark-gluon plasma (QGP). Upon fixing the scale of the thermal coupling constant and vacuum energy to the lattice data, the properties of resulting QGP equations of state (EoS) are developed. We show that the physical properties of the dense m

T. Champel, V. P. Mineev

An analytical form of the quantum magnetization oscillations (de Haas-van Alphen effect) is derived for two- and quasi two-dimensional metals in normal and superconducting mixed states. The theory is developed under condition that the chemical potential is much greater than the cyclotron frequency, which is proved to be valid for using grand canonical ensemb

Naoki Yoshida, Volker Springel, Simon D. M. White, Giuseppe Tormen

We study the formation of dark halos in a $Λ$CDM universe under the assumption that Cold Dark Matter particles have a finite cross-section for elastic collisions. We compare evolution when CDM mean free paths are comparable to halo sizes with the collisionless and fluid limits. We show that a few collisions per particle per Hubble time at halo centre can sub

Marco Godina, Paolo Matteucci, James A. Vickers

In this paper we redefine the well-known metric-affine Hilbert Lagrangian in terms of a spin-connection and a spin-tetrad. On applying the Poincaré-Cartan method and using the geometry of gauge-natural bundles, a global gravitational superpotential is derived. On specializing to the case of the Kosmann lift, we recover the result originally found by Kijowski

Anita Mehta, G. C. Barker

We show that tilting a model sandpile that has dynamic disorder leads to bistability and hysteresis at the angle of repose. Also the distribution of {\it local slopes} shows an interesting dependence on the amount of tilt - weakly tilted sandpiles retain the quasi-continuous distributions of the steady state, while large tilt makes the distribution more disc

A. Refolli, N. Terzi, D. Zanon

We present a N=2 supersymmetric action for the Born Infeld theory in the non abelian case. We quantize the theory in N=1 superspace and compute divergences at one-loop. The result is discussed in the N=4 case.

Yoshio Koide, Ambar Ghosal

Based on the &#34;democratic&#34; universal seesaw model, where mass matrices $M_f$ of quarks and leptons f_i (f=u,d,ν,e; i=1,2,3) are given by a seesaw form M_f\simeq -m_L M_F^{-1} m_R, and m_L and m_R are universal for all the fermion sectors, and the mass matrices M_F of hypothetical heavy fermions F_i have a democratic structure, a possible neutrino mass

Tohsuke Urabe

This is the manuscript for Proceedings of International Conference and Workshop on Valuation Theory held at University of Saskachewan, Canada in 1999. I have succeeded in showing that any two-dimensional hypersurface singularities of germs of varieties in any characteristic can be resolved by iterated monoidal transformations with centers in smooth subvariet

Alexei Vazquez

A non conservative Abelian sandpile model with BTW toppling rule introduced in [Tsuchiya and Katori, Phys. Rev. E {\bf 61}, 1183 (2000)] is studied. Using a scaling analysis of the different energy scales involved in the model and numerical simulations it is shown that this model belong to a universality class different from that of previous models considere

S. Cristiani, V. D&#39;Odorico

We report on high-resolution observations ($\Re \simeq 45000$) of the Hubble Deep Field South QSO J2233-606 obtained with the VLT UV-Visual Echelle Spectrograph (UVES). We present spectral data for the wavelength region $3050 < λ< 10000$ Å. The $S/N$ ratio of the final spectrum is about 50 per resolution element at 4000 Å, 90 at 5000 Å, 80 at 6000 Å, 40 at 8

Chigak Itoi, Shaojin Qin

We study a spin 1/2 Heisenberg zigzag spin chain model near decoupled two chains. Taking into account a symmetry breaking perturbation, we discuss the existence of an energy gap in the ferromagnetic interchain coupling as well as the antiferromagnetic one. In the ferromagnetic model, a marginally relevant fixed line reduces the gap strongly, so that the corr

Y. Naveh, Vijay Patel, D. V. Averin, K. K. Likharev

We report the observation of the universal distribution of transparencies, predicted by Schep and Bauer [Phys. Rev. Lett. {\bf 78}, 3015 (1997)] for dirty sharp interfaces, in uniform Nb/AlO$_x$/Nb junctions with high specific conductance ($10^8$ Ohm$^{-1}$cm$^{-2}$). Experiments used the BCS density of states in superconducting niobium for transparency dist

Tim R. Morris

A manifestly gauge invariant and regularized renormalization group flow equation is constructed for pure SU(N) gauge theory in the large N limit. In this way we make precise and concrete the notion of a non-perturbative gauge invariant continuum Wilsonian effective action. Manifestly gauge invariant calculations may be performed, without gauge fixing, and re

Charles H. Bennett, David P. DiVincenzo, Peter W. Shor, John A. Smolin

Quantum teleportation uses prior entanglement and forward classical communication to transmit one instance of an unknown quantum state. Remote state preparation (RSP) has the same goal, but the sender knows classically what state is to be transmitted. We show that the asymptotic classical communication cost of RSP is one bit per qubit - half that of teleport

Vladimir Buzek, Peter L. Knight, Nobuyuki Imoto

How much information about the original state preparation can be extracted from a quantum system which already has been measured? That is, how many independent (non-communicating) observers can measure the quantum system sequentially and give a nontrivial estimation of the original unknown state? We investigate these questions and we show from a simple examp

Vladimir Buzek, Mark Hillery

It is not possible to disentangle a qubit in an unknown state $|ψ>$ from a set of (N-1) ancilla qubits prepared in a specific reference state $|0>$. That is, it is not possible to {\em perfectly} perform the transformation $(|ψ,0...,0\r +|0,ψ,...,0\r +...+ |0,0,...ψ\r) \to |0,...,0>\otimes |ψ>$. The question is then how well we can do? We consider a number o

Vladimir Buzek, Mark Hillery

We analyze various scenarios for entangling two initially unentangled qubits. In particular, we propose an optimal universal entangler which entangles a qubit in unknown state $|Ψ>$ with a qubit in a reference (known) state $|0>$. That is, our entangler generates the output state which is as close as possible to the pure (symmetrized) state $(|Ψ>|0> +|0>|Ψ>)

S. Kulin, T. C. Killian, S. D. Bergeson, S. L. Rolston

We report the observation of plasma oscillations in an ultracold neutral plasma. With this collective mode we probe the electron density distribution and study the expansion of the plasma as a function of time. For classical plasma conditions, i.e. weak Coulomb coupling, the expansion is dominated by the pressure of the electron gas and is described by a hyd

R. J. S. Lee, J. V. Mullan, J. F. McCann, D. S. F. Crothers

Results are presented for simulations of electron-positron pair production in relativistic heavy-ion collisions leading to electron capture and positron ejection. We apply a two-center relativistic continuum distorted-wave model to represent the electron/positron dynamics during the collision process. The results are compared with experimental cross-section

H. V. Klapdor-Kleingrothaus, H. Päs

This article provides a (semi-)popular introduction to the phenomenology of neutrino masses.

Alessandro B. Romeo

The workshop `Astrophysical Dynamics 1999/2000&#39; followed a homonymous advanced research course, and both activities were organized by me. In this opening paper of the proceedings book, I describe them and document their strong impact on the academic life of the local institutions. The advanced research course was open to graduate students, senior researc

K. Yu. Kazakov, S. Eh. Shirmovsky

In plane wave one-body approximation the reaction of deuteron photodisintegration is considered in the framework of the Bethe-Salpeter formalism for two-nucleon system. Results are obtained for deuteron vertex function, which is the solution of the homogeneous Bethe-Salpeter equation with a multi-rank separable interaction kernel, with a given analytical for

R. Machleidt

We present a charge-dependent nucleon-nucleon (NN) potential that fits the world proton-proton data below 350 MeV available in the year of 2000 with a chi^2 per datum of 1.01 for 2932 data and the corresponding neutron-proton data with chi^2/datum = 1.02 for 3058 data. This reproduction of the NN data is more accurate than by any phase-shift analysis and any

R. R. Rodriguez-Guzman, J. L. Egido, L. M. Robledo

Properties like the excitation energy with respect to the ground state, moments of inertia, B(E2) transition probabilities and stability against quadrupole fluctuations at low spin of the predicted superdeformed band of ^{32}S are studied with the Gogny force D1S using the angular momentum projected generator coordinate method for the axially symmetric quadr

M. T. Peña, H. Garcilazo, D. O. Riska

The $π$, $η$ and $ρ$ exchange contributions to the cross-section for the reaction $pp\to ppη$ near threshold are calculated with a phenomenological description of the intermediate S11 (N(1535)) resonance for all exchange mechanisms. The final state interaction in the $pp$ system is described by realistic nucleon-nucleon interaction models. The sensitivity of

M. Bhattacharya, C. D. Goodman, R. S. Raghavan, M. Palarczyk

We report a 0-degree 176Yb(p,n)176Lu measurement at IUCF where we used 120 and 160 MeV protons and the energy dependence method to determine GT matrix elements relative to the Fermi matrix element which can be calculated model independently. The data show that there is an isolated concentration of GT strength in the low lying 1+ states making the proposed Lo

P. Crochet, N. Herrmann, K. Wisniewski, Y. Leifels

Experimental data on K+ meson and proton sideward flow measured with the FOPI detector at SIS/GSI in the reactions Ru+Ru at 1.69 AGeV and Ni+Ni at 1.93 AGeV are presented. The K+ sideward flow is found to be anti-correlated (correlated) with the one of protons at low (high) transverse momenta. When compared to the predictions of a transport model, the data f

G. Boffetta, S. Musacchio

The predictability problem in the inverse energy cascade of two-dimensional turbulence is addressed by means of direct numerical simulations. The growth rate as a function of the error level is determined by means of a finite size extension of the Lyapunov exponent. For error within the inertial range, the linear growth of the error energy, predicted by dime

Boris Chirikov

The mechanism of the exponential transient statistics of Poincaré recurrences in the presence of chaos border with its critical structure is studied using two simple models: separatrix map and the kicked rotator (&#39;microtron&#39;). For the exponential transient to exist the two conditions have been shown to be crucial: fast (ballistic) relaxation, and a s

V. K. Kharchenko

We study the various term operations on the set of skew primitive elements of Hopf algebras, generated by skew primitive semi-invariants of an Abelian group of grouplike elements. All 1-linear binary operations are described and trilinear and quadrilinear operations are given a detailed treatment. Necessary and sufficient conditions for the existence of mult

James Allen Fill, Clyde H. Schoolfield,

We develop a method for analyzing the mixing times for a quite general class of Markov chains on the complete monomial group G \wr S_n (the wreath product of a group G with the permutation group S_n) and a quite general class of Markov chains on the homogeneous space (G \wr S_n) / (S_r \times S_{n - r}). We derive an exact formula for the L^2 distance in ter

Bernhard Kroetz, Karl-Hermann Neeb

In this paper we give a classification of the $H$-spherical unitary highest weight representations of a hermitian Lie group $G$.

G. Giachetta, L. Mangiarotti, G. Sardanashvily

We obtain the cohomology of the variational bicomplex on the infinite order jet space of a smooth fiber bundle in the class of exterior forms of finite jet order. This provides a solution of the global inverse problem of the calculus of variations of finite order on fiber bundles.

Gianni Dal Maso, Maria Giovanna Mora, Massimiliano Morini

Using a calibration method, we prove that, if $w$ is a function which satisfies all Euler conditions for the Mumford-Shah functional on a two-dimensional open set $Ω$, and the discontinuity set of $w$ is a segment connecting two boundary points, then for every point $(x_0, y_0)$ of $Ω$ there exists a neighbourhood $U$ of $(x_0, y_0)$ such that $w$ is a minim