August 2000 arXiv papers — page 13

G. Kälbermann

The phenomenon of wave packet diffraction in space and time is described. It consists in a diffraction pattern whose spatial location progresses with time. The pattern is produced by wave packet quantum scattering off an attractive or repulsive time independent potential. An analytical formula for the pattern at $t\to\infty$ is derived both in one dimension

W. I. Goldburg, J. R. Cressman, Z. Voros, B. Eckhardt

We report an experimental and numerical study of turbulent fluid motion in a free surface. The flow is realized experimentally on the surface of a tank filled with water stirred by a vertically oscillating grid positioned well below the surface. Particles floating on the surface are used to visualize the flow. The effect of surface waves appears to be neglig

W. Grimus, L. Lavoura

We develop a recipe which allows one to recursively and uniquely decouple the large scale from the small scale in mass matrices of the seesaw type, up to any order in the inverse of the large scale. Our method allows one to calculate the mass matrix of the light neutrinos with arbitrary precision. The same method can be applied in the case of quark mass matr

Nicole F. Bell, Raymond R. Volkas

We construct a model which provides maximal mixing between a pseudo-Dirac $ν_μ/ν_τ$ pair, based on a local $U(1)_{L_μ-L_τ}$ symmetry. Its strengths, weaknesses and phenomenological consequences are examined. The mass gap necessitated by the pseudo-Dirac structure is most naturally associated with the LSND anomaly. The solar neutrino problem then requires a l

Fulvio Melia, Siming Liu, Robert Coker

The recent detection of significant linear polarization at mm and sub-mm wavelengths in the spectrum of Sgr A* (if confirmed) will be a useful probe of the conditions within several Schwarzschild radii ($r_S$) of the event horizon at the Galactic Center. Hydrodynamic simulations of gas flowing in the vicinity of this object suggest that the infalling gas cir

F. B. J. Buchkremer, R. Dumke, H. Levsen, G. Birkl

We experimentally demonstrate and systematically study the stimulated revival (echo) of motional wave packet oscillations. For this purpose, we prepare wave packets in an optical lattice by non-adiabatically shifting the potential and stimulate their reoccurence by a second shift after a variable time delay. This technique, analogous to spin echoes, enables

David B. Johnson, W. C. Shieve

We present a general method for the derivation of various statistical quantities describing the detection of a beam of atoms emerging from a micromaser. The user of non-normalized conditioned density operators and a linear master equation for the dynamics between detection events is discussed as are the counting statistics, sequence statistics, and waiting t

Steven Leppard, Alice Rogers

Motivated by application to quantum physics, anticommuting analogues of Wiener measure and Brownian motion are constructed. The corresponding Ito integrals are defined and the existence and uniqueness of solutions to a class of stochastic differential equations is established. This machinery is used to provide a Feynman-Kac formula for a class of Hamiltonian

Oliver Cohen

Two objections have been raised to the arguments presented in O. Cohen, Phys. Rev. A 60, 80 (1999). It is pointed out that neither objection has anything whatsoever to do with the main subject matter of that paper, and shown that both objections are based on misunderstandings of the examples to which they relate.

J. Grondalski, P. M. Alsing, I. H. Deutsch

We study the stabilization of coherent suppression of tunneling in a driven double-well system subject to random periodic $δ-$function ``kicks''. We model dissipation due to this stochastic process as a phase diffusion process for an effective two-level system and derive a corresponding set of Bloch equations with phase damping terms that agree with

Mio Murao, Vlatko Vedral

Remote information concentration, the reverse process of quantum telecloning, is presented. In this scheme, quantum information originally from a single qubit, but now distributed into three spatially separated qubits, is remotely concentrated back to a single qubit via an initially shared entangled state without performing any global operations. This entang

S. Lidia, T. Houck, G. Westenskow

The successful operation of a Two-Beam accelerator based on extended relativistic klystrons hinges upon decreasing the cumulative dipole BBU growth from an exponential to a more manageable linear growth rate. We describe the theoretical scheme to achieve this, and a new experiment to test this concept. The experiment utilizes a 1-MeV, 600-Amp, 200-ns electro

William A. Reass, James D. Doss, Robert F. Gribble, Michael T. Lynch

This paper describes electrical design and operational characteristics of a zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metall

S. Lidia, J. Gardelle, T. Lefevre, J. T. Donohue

Recent experiments [1] have explored the use of a free-electron laser (FEL) as a buncher for a microwave two-beam accelerator, and the subsequent driving of a standing-wave rf output cavity. Here we present a deeper analysis of the longitudinal dynamics of the electron bunches as they are transported from the end of the FEL and through the output cavity. In

K. C. D. Chan, B. M. Campbell, D. C. Gautier, R. C. Gentzlinger

This paper describes the development progress of high current superconducting RF linacs in Los Alamos, performed to support a design of the linac for the APT (Accelerator Production of Tritium) Project. The APT linac design includes a CW superconducting RF high energy section, spanning an energy range of 211 to 1030 MeV, and operating at a frequency of 700 M

T. L. Smith, M. H. Cho, A. E. Grelick, G. Pile

The S-band linear accelerator, which was built to be the source of particles and the front end of the Advanced Photon Source injector, is now also being used to support a low-energy undulator test line (LEUTL) and to drive a free-electron laser (FEL). The more severe rf stability requirements of the FEL have resulted in an effort to identify sources of phase

R. Duperrier, R. Ferdinand, J. -M. Lagniel, N. Pichoff

A CW high power linear accelerator can only work with very low particles losses and structure activation. At low energy, the RFQ is a very sensitive element to losses. To design the RFQ, a good understanding of the beam dynamics is requested. Generally, the reference code PARMTEQM is enough to design the accelerator. TOUTATIS has been written with goals of c

M. G. Mazarakis, R. B. Spielman, K. W. Struve, F. W. Long

Saturn is a dual-purpose accelerator. It can be operated as a large-area flash x-ray source for simulation testing or as a Z-pinch driver especially for K-line x-ray production. In the first mode, the accelerator is fitted with three concentric-ring 2-MV electron diodes, while in the Z-pinch mode the current of all the modules is combined via a post-hole con

Yu-Jiuan Chen, Darwin D. -M. Ho, James F. Mccarrick, Arthur C. Paul

We have modified the single pulse target experimental facility[ ] on the Experimental Test Accelerator II (ETA-II) to perform the double pulse target experiments to validate the DARHT-II[, ] multi-pulse target concept. The 1.15 MeV, 2 kA Snowtron injector will provide the first electron pulse. The 6 MeV, 2 kA ETA-II beam will be used as the probe beam. Our m

Yu-Jiuan Chen, Arthur C. Paul

Diagnostic X (D-X) transport system would extract the beam from the downstream transport line of the second- axis of the Dual Axis Radiographic Hydrodynamic Test facility (DARHT-II) and transport this beam to the D-X firing point via four branches of the beamline in order to provide four lines of sight for x-ray radiography. The design goal is to generate fo

H. H. Braun, R. Corsini, L. Groening, F. Zhou

Bunches of high charge (up to 10 nC) are compressed in length in the CTF II magnetic chicane to less than 0.2 mm rms. The short bunches radiate coherently in the chicane magnetic field, and the horizontal and longitudinal phase space density distributions are affected. This paper reports the results of beam emittance and momentum measurements. Horizontal and

Nicholas Sereno, Michael Borland, Alex Lumpkin

We describe use of the Advanced Photon Source (APS) rf thermionic gun, alpha magnet beamline, and linac to produce a stable high-brightness beam in excess of 100 amperes peak current with normalized emittance of 10 pi mm-mrad. To obtain peak currents greater than 100 amperes, the rf gun system must be tuned to produce a FWHM bunch length on the order of 350

A. V. Feschenko, V. A. Moiseev

The operation and parameters of Bunch Shape Monitors using coherent transformation of time structure of an analyzed beam into a spatial one of low energy secondary electrons emitted from a wire target is influenced by the characteristics of a beam under study. The electromagnetic field of a bunch disturbs the trajectories of secondary electrons, thus resulti

Michael Borland, John Lewellen, Steve Milton

The LEUTL FEL at the APS has achieved gain at 530 nm with peak beam current \~100 A. In an effort to push to 120 nm and beyond, we have designed and are commissioning a bunch compressor to increase the peak current to 600 A or more. The bunch compressor uses a four-dipole chicane at an energy of 100 to 210 MeV. To provide options for control of emittance gro

Amy Regan, Sung-il Kwon, Tony S. Rohlev, Yi-Ming Wang

The Spallation Neutron Source (SNS) is being designed for operation in 2004. The SNS is a 1 GeV machine consisting of a combination normal-conducting and super-conducting linac as well as a ring and target area. The linac front end is a 402.5 MHz RFQ being developed by Lawrence Berkeley Lab. The DTL (at 402.5 MHz) and the CCL (at 805 MHz) stages are being de

Michael Borland

A magnetic bunch compressor has been designed and is being commissioned for the APS linac to provide higher peak current for the LEUTL FEL. Of primary concern is control of emittance growth due to coherent synchrotron radiation (CSR). In addition, tolerances must be carefully evaluated in order to choose the most stable operating conditions and ensure that t

J. Glatz, J. Klabunde, U. Scheeler, D. Wilms

With the new GSI High Current Injector, the beam pulse intensity will be increased by more than two orders of magnitude. The high beam power and the short stopping range at particle energies below 12 MeV/u can destroy accelerator components even during a single beam pulse. Therefore, the operation of the whole accelerator facility has required major changes

Anatoly Krasnykh

Analyze of experimental results shows that the energy discharge efficiency of the modern modulators is 0.92-0.93. The energy transfer efficiency can be reached up to 0.7 for 1.5 usec pulse width and up to 0.8 for 3.0 usec accordingly. The geometry and core material of the transformer is one element of modulator, which limits the efficiency due to limitation

M. Syphers, L. Michelotti

An alternative being considered for the Next Linear Collider (NLC) is not to tunnel in a straight line but to bend the Main Linac into an arc so as to follow an equipotential. We begin here an examination of the effects that this would have on vertical dispersion, with its attendant consequences on synchrotron radiation and emittance growth by looking at two

G. Spalek, D. W. Christiansen, P. D. Smith, P. T. Greninger

The cw CCL being designed for the Accelerator Production of Tritium (APT) project accelerates protons from 96MeV to 211MeV. It consists of 99 segments each containing up to seven accelerating cavities. Segments are coupled by intersegment coupling cavities and grouped into supermodules. The design method needs to address not only basic cavity sizing for a gi

M. Pabst, K. Bongardt, A. Letchford

Three alternative designs of the European Spallation Source (ESS) high energy linac are described. The most promising ones are either a normalconducting (nc) coupled cavity linac (CCL) up tofinal energy or a change at 407 MeV to only one group of 6 cell superconducting (sc) elliptical cavities. Fully 3d Monte Carlo simulations are presented for both options,

A. Sauer, H. Deitinghoff, H. Klein

Recent ion source developments resulted in the generation of high brilliance, high current beams of protons and light ions. After extraction and transport the beams with large internal space charge forces have to be captured, bunched and preaccelerated for the injection into the following driver part of a new generation of high intensity beam facilities for

N. Baboi, M. Ferrario, M. Liepe, J. Sekutowicz

A new cavity-chain layout has been proposed for the main linac of the TESLA linear collider. This superstructure-layout is based upon four 7-cell superconducting standing-wave cavities, coupled by short beam pipes. The main advantages of the superstructure are an increase in the active accelerating length in TESLA and a saving in rf components, especially po

P. Forck, F. Heymach, T. Hoffmann, A. Peters

For the characterization of the 10 mA ion beam delivered by the new High Current Linac at GSI, sophisticated, mainly non-intersepting diagnostic devices were developed. Besides the general set-up of a versatile test bench, we discuss in particular bunch shape and emittance measurements. A direct time-of-flight technique with a diamond particle detector is us

C. E. Hill, A. Lombardi, R. Scrivens, M. Vretenar

As the pre-injector of the LHC injector chain, the proton linac at CERN is required to provide a high-intensity (180mA) beam to the Proton Synchrotron Booster. The results of measurements at this intensity will be presented. Furthermore, the linac is now equipped with bunch shape monitors from INR, Moscow, which have allowed the comparison of the Alvarez tan

I. Wilson, W. Wuensch

This paper outlines the RF design of the CLIC (Compact Linear Collider) 30 GHz main linac accelerating structure and gives the resulting longitudinal and transverse mode properties. The critical requirement for multibunch operation, that transverse wakefields be suppressed by two orders of magnitude within 0.7 ns (twenty fundamental mode cycles), has been de

5 Team

Preinjector VEPP-5 electron linac consists of two linear accelerators on energy 300 MeV and 510 MeV and includes 14 accelerating structures [1]. First accelerating structures both linacs have increased average rate of acceleration 25-30 MeV/m, and other regular sections up to 17-20 MeV/m. This paper presents the results of basic test of 3-meter long accelera

S. Fukuda, A. Anami, C. Kubota, M. Kawamura

The construction of the 60-MeV proton linac has started as a low-energy front of the KEK/JAERI Joint Project for a high-intensity proton accelerator facility at KEK. The accelerating frequency is 324 MHz. Five UHF klystrons are used as an rf source; their ratings have a maximum power of 3 MW, a beam pulse width of a 700 micro-sec (an rf pulse width is 650 mi

C. P. Welsch, K. U. Kuehnel, A. Schempp

A focus of work at IAP has been the development and optimization of spiral loaded cavities since the 1970s [A. Schempp et al, NIM 135, 409 (1976)]. These cavities feature a high efficiency, a compact design and a big variety of possible fields of application. They find use both as bunchers and post accelerators to vary the final energy of the beam. In compar

A. Fix, H. Arenhoevel

A three-body calculation of the reaction $γd\toηnp$ in the energy region from threshold up to 30 MeV above has been performed. The primary goal of this study is to assess the importance of the three-body aspects in the hadronic sector of this reaction. Results are presented for the $η$-meson spectrum as well as for the total cross section. The three-body res

L. Ahle, E866, E917 Collaborations

Mid-rapidity spectra and yields of K$^-$ and K$^+$ have been measured for Au+Au collisions at 4, 6, 8, and 10.7 AGeV. The K$^-$ yield increases faster with beam energy than for K$^+$ and hence the K$^-$/K$^+$ ratio increases with beam energy. This ratio is studied as a function of both $\sqrt{s}$ and $\sqrt{s}$-$\sqrt{s_{th}}$ which allows the direct compari

Bruno Eckhardt, Imre Varga, Peter Pollner

We discuss the fluctuation properties of diagonal matrix elements in the semiclassical limit in chaotic systems. For extended observables, covering a phase space area of many times Planck's constant, both classical and quantal distributions are Gaussian. If the observable is a projection onto a single state or an incoherent projection onto several states

Bruno Eckhardt, Shmuel Fishman, Imre Varga

We calculate within a semiclassical approximation the autocorrelation function of cross sections. The starting point is the semiclassical expression for the diagonal matrix elements of an operator. For general operators with a smooth classical limit the autocorrelation function of such matrix elements has two contributions with relative weights determined by

C. Burdik, O. Navratil

Systems of nonlinear ordinary differential equations are constructed, for which the general solution is algebraically expressed in terms of a finite number of particular solutions. Expressions of that type are called the nonlinear superposition formulas. These systems are connected with local Lie groups tranformations on their homogeneous spaces. In the pres

Ali Mohammad-Djafari

A complete solution for an inverse problem needs five main steps: choice of basis functions for discretization, determination of the order of the model, estimation of the hyperparameters, estimation of the solution, and finally, caracterisation of the proposed solution. Many works have been done for the three last steps. The two first have been neglected for

Ali Mohammad-Djafari

Source separation is one of the signal processing's main emerging domain. Many techniques such as maximum likelihood (ML), Infomax, cumulant matching, estimating function, etc. have been used to address this difficult problem. Unfortunately, up to now, many of these methods could not account completely for noise on the data, for different number of sourc

Satyan L. Devadoss

We construct a new (cyclic) operad of `mosaics' defined by polygons with marked diagonals. Its underlying (aspherical) spaces are the sets of real points of the moduli space of punctured Riemann spheres, which are naturally tiled by Stasheff associahedra. We (combinatorially) describe them as iterated blow-ups and show that their fundamental groups form

Satyan L. Devadoss, Ronald C. Read

The polytope structure of the associahedron is decomposed into two categories, types and classes. The classification of types is related to integer partitions, whereas the classes present a new combinatorial problem. We solve this and incorporate the results into properties of the real moduli space of Riemann spheres. Connections are discussed with relation

Esteban Andruchow, Alejandro Varela

Let $B$ be a C$^*$-algebra and $X$ a C$^*$ Hilbert $B$-module. If $p\in B$ is a projection, denote by $S_p =\{x\in X : < x,x> =p\}$, the $p$-sphere of $X$. For $ϕ$ a state of $B$ with support $p$ in $B$ and $x\in S_p$, consider the state $ϕ_x$ of $L_B(X)$ given by $ϕ_x(t)= ϕ(< x,t(x)>)$. In this paper we study certain sets associated to these states, and exa

Maria Gorelik

In this article we prove that for a basic classical Lie superalgebra the annihilator of a strongly typical Verma module is a centrally generated ideal. For a basic classical Lie superalgebra of type I we prove that the localization of the enveloping algebra by a certain central element is free over its centre.

Tsit-Yuen Lam, André Leroy

A Wedderburn polynomial over a division ring K is a minimal polynomial of an algebraic subset of K. Special cases of such polynomials include, for instance, the minimal polynomials (over the center F=Z(K)) of elements of K that are algebraic over F. In this note, we give a survey on some of our ongoing work on the structure theory of Wedderburn polynomials.

Ken Ono

Ramanujan (and others) proved that the partition function satisfies a number of striking congruences modulo powers of 5, 7 and 11. A number of further congruences were shown by the works of Atkin, O&#39;Brien, and Newman. In this paper we prove that there are infinitely many such congruences for every prime modulus exceeding 3. In addition, we provide a simp

Kazuo Akutagawa, Boris Botvinnik

We study here compact manifolds with positive scalar curvature metrics. We use the relative Yamabe invariant from math.DG/0008138 to define the conformal cobordism relation on the category of such manifolds. We prove that corresponding conformal cobordism groups $\Pos_n^{\conf}(γ)$ are isomorphic to the cobordism groups $\Pos_n(γ)$ defined topologically by S

Kazuo Akutagawa, Boris Botvinnik

We define a relative Yamabe invariant of a smooth manifold with given conformal class on its boundary. In the case of empty boundary the invariant coincides with the classic Yamabe invariant. We develop approximation technique which leads to gluing theorems of two manifolds along their boundaries for the relative Yamabe invariant. We show that there are many

E. B. Davies

We define a class of pseudo-ergodic non-self-adjoint Schrödinger operators acting in spaces $l^2(X)$ and prove some general theorems about their spectral properties. We then apply these to study the spectrum of a non-self-adjoint Anderson model acting on $l^2(\Z)$, and find the precise condition for 0 to lie in the spectrum of the operator. We also introduce

G. Roepstorff

In a previous paper (hep-th/9801040), the superconnection formalism was used to fit the Higgs field into a U(n) gauge theory with particular emphasis on the n=2 case, aiming at the reconstruction of certain parts of the Standard Model. The approach provides an alternative to the one bases on non-commutative geometry. This work is continued by including matte

Alfredo T. Suzuki, Alexandre G. M. Schmidt

We apply negative dimensional integration method (NDIM) to three outstanding gauges: Feynman, light-cone and Coulomb gauges. Our aim is to show that NDIM is a very suitable technique to deal with loop integrals, being them originated from any gauge choice. In Feynman gauge we perform scalar two-loop four-point massless integrals; in the light-cone gauge we c

Gerald Dunne, Alex Kovner, Bayram Tekin

We study the locality properties of the vortex operators in compact U(1) Maxwell-Chern-Simons and SU(N) Yang-Mills-Chern-Simons theories in 2+1 dimensions. We find that these theories do admit local vortex operators and thus in the UV regularized versions should contain stable magnetic vortices. In the continuum limit however the energy of these vortex excit

M. Cataldo, N. Cruz, S. del Campo, A. Garcia

A (2+1)-static black hole solution with a nonlinear electric field is derived. The source to the Einstein equations is a nonlinear electrodynamics, satisfying the weak energy conditions, and it is such that the energy momentum tensor is traceless. The obtained solution is singular at the origin of coordinates. The derived electric field E(r) is given by $E(r

G. Cognola, S. Zerbini

The procedure of the dimensional reduction related to the partition function of a quantum field living in curved space-time which is the warp product of a symmetric space is investigated.

M. Caldarelli, L. Vanzo, S. Zerbini

The extreme limit of a class of D-dimensional black holes is revisited. In the static limit, it is shown that well defined extremal limiting procedure exists and it leads to new solutions of the type AdS2 times constant curvature symmetric spaces.

Ichiro Oda

We show how the spin 3/2 gravitino field can be localized on a brane in a general framework of supergravity theory. Provided that a scalar field coupled to the Rarita-Schwinger field develops an vacuum expectation value (VEV) whose phase depends on the &#39;radial&#39; coordinate in extra internal space, the gravitino is localized on a brane with the exponen

Keiichi Akama, Takashi Hattori

We show how the gravity, extrinsic curvature, and gauge field theories are induced on dynamically localized brane world. They should obey the Gauss-Codazzi-Ricci equation in addition to their own equations of motion. As an example, we derive the solitonic solution for curved domain wall in five dimensions in terms of gravity and extrinsic curvature fields of

G. Giachetta, L. Mangiarotti, G. Sardanashvily

The iterated BRST cohomology is studied by computing cohomology of the variational complex on the infinite order jet space of a smooth fibre bundle. This computation also provides a solution of the global inverse problem of the calculus of variations in Lagrangian field theory.

A. Bramon, R. Escribano, J. L. Lucio M., M. Napsuciale

The radiative $ϕ\toπ^0ηγ$ decay is discussed emphasizing the effects of the $a_0$(980) scalar resonance which dominates the high values of the $π^0η$ invariant mass spectrum. In its lowest part, the proposed amplitude coincides with the reliable and ChPT-inspired contribution coming from chiral loops. The $a_0$(980) resonance is then incorporated exploiting

M. V. Chizhov

All known elementary vector particles, the photon, Z, W and the gluons, are described by the gauge theory. They belong to the real representation (1/2,1/2) of the Lorentz group. On the other hand inequivalent representations (1,0) and (0,1) also correspond to particles with spin 1. It is natural to suppose that, along with the known vector particles, the new

M. Anselmino, D. Boer, U. D&#39;Alesio, F. Murgia

The longstanding problem of explaining the observed polarization of Lambda hyperons inclusively produced in the high energy collisions of unpolarized hadrons is tackled by considering spin and k_T dependent quark fragmentation functions. The data on Lambda&#39;s and Lambda-bar&#39;s produced in p-N processes are used to determine simple phenomenological expr

Sachiko Takeuchi

Effects of the $Σ$N channels on the spin-orbit force in $Λ$-hypernuclei are investigated. It is found that the cancellation between the symmetric and the antisymmetric $Λ$N spin-orbit force becomes more complete when the contribution from the $Σ$N channels is included. This may be the one of the reasons why the observed LS splitting of the $Λ$ single particl

H. Päs, M. Hirsch, H. V. Klapdor-Kleingrothaus, S. G. Kovalenko

A general Lorentz-invariant parameterization for the short-range part of the 0vBB decay rate is derived. Combined with the long range part already published this general parameterization in terms of effective B-L violating couplings allows one to extract the 0vBB limits on arbitrary lepton number violating theories.

Nadia Fettes, Ulf-G. Meißner

We investigate isospin breaking in low-energy pion-nucleon scattering in the framework of chiral perturbation theory. This work extends the systematic analysis of [1] to the energy range above threshold. Various relations, which identically vanish in the limit of isospin symmetry, are used to quantify isospin breaking effects. We study the energy dependence

Stefan Wolf

We investigate energy (momentum) distributions in J/Psi photoproduction and J/Psi production in B meson decay. In particular the upper endpoint region of the spectrum is examined where the effect of soft gluon emission from the ccbar pair becomes important. Constructing a model which is consistent with the so-called shape function formalism we consider these

Sachiko Takeuchi, Yoshihiro Tani, Makoto Oka

We investigate the symmetric and anti-symmetric spin-orbit forces (SLS and ALS) of the effective $Λ$N interaction derived from a quark cluster model with the instanton-induced interaction (\III), which can reproduce the observed YN cross sections as well as the observed NN scattering data. It is found that coupling to the $Σ$N channel enhances $Λ$N ALS, and

Wojciech Broniowski

We analyze experimental particle spectra and show that the Hagedorn temperature is significantly larger for mesons than for baryons. The effect can be explained within dual string models: excitations of three strings in the baryon produce ``faster&#39;&#39; combinatorics than a single string in the meson, hence lead to a more rapid growth of baryons than mes

J. Z. Bai

A sample of 3.95M $ψ(2S)$ decays registered in the BES detector are used to study final states containing pairs of octet and decuplet baryons. We report branching fractions for $ψ(2S)\to p\bar{p}$, $Λ\barΛ$, $Σ^0\barΣ{}^0$, $Ξ^-\barΞ{}^+$, $Δ^{++}\barΔ{}^{--}$, $Σ^+(1385)\barΣ{}^-(1385)$, $Ξ^0(1530)\barΞ{}^0(1530)$, and $Ω^-\barΩ{}^+$. These results are comp

Erik F. Tjong Kim Sang, Walter Daelemans, Herve Dejean, Rob Koeling

We use seven machine learning algorithms for one task: identifying base noun phrases. The results have been processed by different system combination methods and all of these outperformed the best individual result. We have applied the seven learners with the best combinator, a majority vote of the top five systems, to a standard data set and managed to impr

M. G. Moore, Pierre Meystre

We compare the efficiency of four-wave mixing in quantum degenerate gases of bosonic and fermionic atoms. It is shown that matter-wave gratings formed from either bosonic or fermionic atoms can in principle exhibit nearly identical Bragg-scattering, i.e. four-wave mixing, properties. This implies that effects such as coherent matter-wave amplification and su

S. G. Magalhaes, A. A. Schmidt

We have analyzed a fermionic infinite-ranged quantum Heisenberg spin glass with BCS coupling in real space in the presence of a magnetic field. It has been possible to locate the transition line between the normal paramagnetic phase (NP) and the phase where there is a long range order corresponding to pair formation in sites (PAIR). The nature of the transit

W. A. M. Morgado, M. M. Doria, G. Carneiro

The vortex state at the lower critical field, H_{c1}, in clean anisotropic superconductors placed in an external field tilted with respect to the axis of anisotropy (c-axis) is considered assuming two possible arrangements: dilute vortex-lines or dilute vortex-line chains. By minimizing the Gibbs free energies in the London limit for each possibility we obta

Ernst Helmut Brandt, Grigorii P. Mikitik

Exact analytic solutions are presented for the magnetic moment and screening currents in the Meissner state of superconductor strips with rectangular cross section in a perpendicular magnetic field and/or with transport current. The extension to finite London penetration is achieved by an elegant numerical method which works also for disks. The surface curre

S. G. Magalhaes, A. A. Schmidt

In the present paper we have analysed a fermionic infinite-ranged quantum Heisenberg spin glass (s=1/2) with a BCS coupling in real space in the presence of an applied magnetic field. This model has been obtained by tracing out the conducting fermions in a superconducting alloy. The magnetic field is applied in the resulting effective model. The problem is f

S. H. Curnoe, A. E. Jacobs

We study the statics and the dynamics of domain patterns in proper hexagonal-orthorhombic ferroelastics; these patterns are of particular interest because they provide a rare physical realization of disclinations in crystals. Both our static and dynamical theories are based entirely on classical, nonlinear elasticity theory; we use the minimal theory consist

I. Campillo, A. Rubio, J. M. Pitarke, A. Goldmann

We present a detailed analysis of hole dynamics in noble metals (Cu and Au), by means of first-principles many-body calculations. While holes in a free-electron gas are known to live shorter than electrons with the same excitation energy, our results indicate that d-holes in noble metals exhibit longer inelastic lifetimes than excited sp-electrons, in agreem

E. Lacaze, M. Alba, M. Goldmann, J. P. Michel

By combining X-ray diffraction studies under grazing incidence (GIXD) and Scanning Tunneling Microscopy (STM) measurements, we have precisely determined the structure of 8CB molecules adsorbed on MoS2, under the thick organic film. The commensurability of the adsorbed network and the intracell structure have been determined, revealing a complex structure cha

M. R. Evans, Y. Kafri, E. Levine, D. Mukamel

The coarsening process in a class of driven systems exhibiting striped structures is studied. The dynamics is governed by the motion of the driven interfaces between the stripes. When two interfaces meet they coalesce thus giving rise to a coarsening process in which l(t), the average width of a stripe, grows with time. This is a generalization of the reacti

Olga V. Kirillova

Topological and metric entropies of the DNA sequences from different organisms were calculated. Obtained results were compared each other and with ones of corresponding artificial sequences. For all envisaged DNA sequences there is a maximum of heterogeneity. It falls in the block length interval [5,7]. Maximum distinction between natural and artificial sequ

Y. Onishi, K. Miyake

Properties of an extended periodic Anderson model with the f-c Coulomb interaction $\Ufc$ is studied as a model for \Ge and related compounds which is cosidered to exhibit a sharp valence change under pressure. The problem is treated by extending the {\it slave-boson} and large-N expansion method to treat the present system. It is shown that, as the f-level

Yu. A. Genenko, A. Snezhko, H. C. Freyhardt

A current-carrying superconducting strip partly penetrated by magnetic flux and surrounded by a bulk magnet of high permeability is considered. Two types of samples are studied: those with critical current controlled by an edge barrier dominating over the pinning, and those with high pinning-mediated critical current masking the edge barrier.It is shown for

Yu. A. Genenko, A. Usoskin, H. C. Freyhardt

A transport current distribution over a wide superconducting sheet is shown to strongly change in a presence of bulk magnetic screens of a soft magnet with a high permeability. Depending on the geometry, the effect may drastically suppress or protect the Meissner state of the sheet through the enhancement or suppression of the edge barrier critical current.

A. N. Morozov, J. G. E. M. Fraaije

The Leibler theory [L. Leibler, Macromolecules, v.13, 1602 (1980)] for microphase separation in AB block copolymer melts is generalized for systems with arbitrary topology of molecules. A diagrammatic technique for calculation of the monomeric correlation functions is developed. The free energies of various mesophases are calculated within the second-harmoni

Kazushige Machida, Tetsuo Ohmi

It is argued that the pairing symmetry realized in a ferromagnetic superconductor UGe$_2$ must be a non-unitary triplet pairing. This particular state is free from the Pauli limitation and can survive under a huge internal molecular filed. To check our identification we examine its basic properties and several experiments are proposed. In particular, the ext

S. -W. Han, J. Farmer, H. Kaiser, P. F. Miceli

We present a quantitative comparison of the magnetization measured by spin-polarized neutron reflectivity (SPNR) and DC magnetometry on a 1370 Å -thick Nb superconducting film. As a function of magnetic field applied in the film plane, SPNR exhibits reversible behavior whereas the DC magnetization shows substantial hysteresis. The difference between these me

S. L. Lou, S. H. Wu

The use of a transfer matrix method to solve the 3D Ising model is straightforwardly generalized from the 2D case. We follow B.Kaufman&#39;s approach. No approximation is made, however the largest eigenvalue cannot be identified. This problem comes from the fact that we follow the choice of directions of 2-dimensional rotations in the direct product space of

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

We report the results of a sensitive near-infrared JHKL imaging survey of the Trapezium cluster in Orion. We use the JHKL colors to obtain a census of infrared excess stars in the cluster. Of (391) stars brighter than 12th magnitude in the K and L bands, 80 +/- 7% are found to exhibit detectable infrared excess on the J-H, K-L color-color diagram. Examinatio

M. E. van den Ancker

An analysis of solid-state features in infrared spectra of 46 Herbig Ae/Be stars is presented. The presence of solid-state emission bands is compared to other indicators of circumstellar material, such as Halpha emission, optical variability and sub-mm continuum fluxes. The correlation between these different indicators is weak, if present at all, in our sam

Roman Scoccimarro

We describe a new approach to gravitational instability in large-scale structure, where the equations of motion are written and solved as in field theory in terms of Feynman diagrams. The basic objects of interest are the propagator (which propagates solutions forward in time), the vertex (which describes non-linear interactions between waves) and a source w

Rodger I. Thompson, Ray J. Weymann, Lisa J. Storrie-Lombardi

This paper presents the star formation history in the NICMOS Northern Deep HDF. It uses the techniques of photometric redshifts and extinctions to correct for extinction of the ultra-violet flux. It presents a new method for correcting for surface brightness diming. It also predicts the 850 micron fluxes of the objects for comparison with SCUBA measurements

T. Narita, P. F. Bloser, J. E. Grindlay, J. A. Jenkins

We present initial results from our evaluation of a gold-contacted pixellated detector using cadmium zinc telluride substrate produced by IMARAD Imaging Systems. The Horizontal Bridgman (HB) grown crystals from IMARAD have been shown to produce high resolution photopeaks, but they are also seen to have large leakage current. Our previous tests with IMARAD CZ

T. Narita, J. E. Grindlay, D. Barret

We report on ASCA observations of the low mass X-ray binaries GX 354-0 and KS 1731-260. The spectrum of GX 354-0 is best described as a power-law or a Comptonized spectrum with tau ~ 5 and kT ~ 8 keV and a residual at ~6.5 keV. The residual may be a disk reflection or a Compton broadened Gaussian line from the hot inner ADAF-like coronal region. The absorpti

A. J. Barth, L. C. Ho, A. V. Filippenko, H. -W. Rix

We report the discovery of an extremely broad H-alpha emission line in the LINER nucleus of NGC 4579. From ground-based observations, the galaxy was previously known to contain a Type 1 nucleus with a broad H-alpha line of FWHM = 2300 km/s and FWZI ~ 5000 km/s. New spectra obtained with the Hubble Space Telescope and a 0.2 arcsec-wide slit reveal an H-alpha

S. Moehler, W. B. Landsman, B. Dorman

Atmospheric parameters (effective temperature, surface gravity) and radial velocities are derived for 12 candidate blue horizontal branch (HB) stars in the globular clusters 47 Tuc and NGC 362, which so far have been known to contain primarily red HB stars. The spectroscopic targets were selected from the catalog of hot stars detected in these clusters at 16