1,061 research outputs found

    Chiral perturbation theory vs. vector meson dominance in the decays ϕργγ\phi \to \rho \gamma \gamma and ϕωγγ\phi \to \omega \gamma \gamma

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    It is pointed out that the radiative decays of a ϕ\phi meson, \phirho and \phiom, receive dominant contributions from the pseudoscalar (P=η,ηP = \eta, \eta^{'}) exchanges. Using the vector meson dominance model, we find that B (\phirho) \approx 1.3 \times 10^{-4} and B (\phiom) \approx 1.5 \times 10^{-5}, which are mainly from the η\eta^{'} pole. Thus, these decays are well within the reach of the ϕ\phi factory. Our estimates are a few orders of magnitude larger than the chiral loop contributions in the heavy vector meson chiral lagrangian, which is about ( a few ) ×109\times 10^{-9}.Comment: 10 pages, 2 Encapsuled-Postscript figures, uses epsfig.st

    Color-octet mechanism in the inclusive D-wave charmonium productions in B decays

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    The inclusive D-wave charmonium production rates in B decays are considered in the Bodwin-Braaten-Lepage (BBL) approach. We find that the color-octet subprocesses B->cc_(^3S_1^(8) or ^3P_J^(8))+s,d, followed by the transition cc_(^3S_1^(8) or ^3P_J^(8)) -> ^3D_J, strongly dominate over any other subprocess, due to the large Wilson coefficient for the \Delta B = 1 effective lagrangian. Assuming that the numerical values of the matrix elements and are the same order of magnitudes with the , we find that the ^{1,3}D_{2} can be observed at future B-factories.Comment: 11 pages, LaTeX, Phys. Lett. B in pres

    Editorial – Special Issue on Collaboration Support Systems (CSS)

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    Recent and emerging advances in computer and information science and technology have realized a powerful computing and communication environment. It enables effective interactions and collaboration among groups of people and systems (and systems-of-systems) beyond traditional restrictions of time and space. The evolution in hardware (e.g., pervasive computing devices, wireless sensor networks, nano-electronics) and software (e.g., multi-agent systems, workflow and information integration, interaction models and protocols) technology, and their flexible teaming have further enabled diverse forms of collaboration approaches. It has been observed during the last few decades that numerous collaboration methodologies, tools and applications in various domains have emerged to provide better quality services, helping to solve domain-specific, highly complex problems. The development of collaboration tools and methodologies has increased the domain knowledge that can be discovered and shared by individuals, and the level and intensity of interactions and collaboration that can dramatically decrease problem complexity and increase solution quality. At the same time, inefficient interactions, task and information overloads, and ineffective collaboration are prevalent

    Single-filament Composite MgB2/SUS Ribbons by Powder-In-Tube Process

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    We report the successful fabrication of single-filament composite MgB2/SUS ribbons, as an ultra-robust conductor type, employing the powder-in-tube (PIT) process, by swaging and cold rolling only. The remarkable transport critical current (Ic) of the non-sintered MgB2/SUS ribbon has observed, as an unexpected result. Transport critical currents Ic ~ 316 A at T = 4.2 K and Ic ~ 82 A at T = 20 K were observed at self-field, for the non-sintered composite MgB2/SUS ribbon. In addition, the persistent current density Jp values, that were estimated by Bean formula, were more than ~ 7  105 A/cm2 at T = 5 K, and ~ 1.2  105 A/cm2 at T = 30 K, for the sintered composite MgB2/SUS ribbon, at H = 0 G.Comment: 10 pages, 4 figure

    The connection between computability of a nonlinear problem and its linearization: the Hartman-Grobman theorem revisited

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    As one of the seven open problems in the addendum to their 1989 book Computability in Analysis and Physics Pour-El and Richards (1989)[17], Pour-El and Richards asked, "What is the connection between the computability of the original nonlinear operator and the linear operator which results from it?" Yet at present, systematic studies of the issues raised by this question seem to be missing from the literature. In this paper, we study one problem in this direction: the Hartman-Grobman linearization theorem for ordinary differential equations (ODEs). We prove, roughly speaking, that near a hyperbolic equilibrium point x(0) of a nonlinear ODE (x) over dot = f(x), there is a computable homeomorphism H such that H circle phi = L circle H, where phi is the solution to the ODE and L is the solution to its linearization (x) over dot = Df (x(0)) x. (C) 2012 Elsevier B.V. All rights reserved.Fundacao para a Ciencia e a Tecnologia; EU FEDER POCTI/POCI via SQIG - Instituto de Telecomunicacoes through the FCT [PEst-OE/EEI/LA0008/2011

    Collective modes of asymmetric nuclear matter in Quantum HadroDynamics

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    We discuss a fully relativistic Landau Fermi liquid theory based on the Quantum Hadro-Dynamics (QHDQHD) effective field picture of Nuclear Matter ({\it NM}). From the linearized kinetic equations we get the dispersion relations of the propagating collective modes. We focus our attention on the dynamical effects of the interplay between scalar and vector channel contributions. A beautiful ``mirror'' structure in the form of the dynamical response in the isoscalar/isovector degree of freedom is revealed, with a complete parallelism in the role respectively played by the compressibility and the symmetry energy. All that strongly supports the introduction of an explicit coupling to the scalar-isovector channel of the nucleon-nucleon interaction. In particular we study the influence of this coupling (to a δ\delta-meson-like effective field) on the collective response of asymmetric nuclear matter (ANMANM). Interesting contributions are found on the propagation of isovector-like modes at normal density and on an expected smooth transition to isoscalar-like oscillations at high baryon density. Important ``chemical'' effects on the neutron-proton structure of the mode are shown. For dilute ANMANM we have the isospin distillation mechanism of the unstable isoscalar-like oscillations, while at high baryon density we predict an almost pure neutron wave structure of the propagating sounds.Comment: 18 pages (LATEX), 8 Postscript figures, uses "epsfig

    SUSY GUT Model Building

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    I discuss an evolution of SUSY GUT model building, starting with the construction of 4d GUTs, to orbifold GUTs and finally to orbifold GUTs within the heterotic string. This evolution is an attempt to obtain realistic string models, perhaps relevant for the LHC. This review is in memory of the sudden loss of Julius Wess, a leader in the field, who will be sorely missed.Comment: 24 pages, 14 figures, lectures given at PiTP 2008, Institute for Advanced Study, Princeton, to be published in the European Physical Journal

    The COSINE-100 liquid scintillator veto system

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    This paper describes the liquid scintillator veto system for the COSINE-100 dark matter experiment and its performance. The COSINE-100 detector consists of eight NaI(Tl) crystals immersed in 2200 L of linear alkylbenzene-based liquid scintillator. The liquid scintillator tags between 65 and 75% of the internal 40K background in the 2–6 keV energy region. We also describe the background model for the liquid scintillator, which is primarily used to assess its energy calibration and threshold

    Search for sterile neutrino oscillation using RENO and NEOS data

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    We present a reactor model independent search for sterile neutrino oscillation using 2\,509\,days of RENO near detector data and 180 days of NEOS data. The reactor related systematic uncertainties are significantly suppressed as both detectors are located at the same reactor complex of Hanbit Nuclear Power Plant. The search is performed by electron antineutrino\,(νe\overline{\nu}_e) disappearance between six reactors and two detectors with baselines of 294\,m\,(RENO) and 24\,m\,(NEOS). A spectral comparison of the NEOS prompt-energy spectrum with a no-oscillation prediction from the RENO measurement can explore reactor νe\overline{\nu}_e oscillations to sterile neutrino. Based on the comparison, we obtain a 95\% C.L. excluded region of 0.1<Δm412<70.1<|\Delta m_{41}^2|<7\,eV2^2. We also obtain a 68\% C.L. allowed region with the best fit of Δm412=2.41±0.03|\Delta m_{41}^2|=2.41\,\pm\,0.03\,\,eV2^2 and sin22θ14\sin^2 2\theta_{14}=0.08±\,\pm\,0.03 with a p-value of 8.2\%. Comparisons of obtained reactor antineutrino spectra at reactor sources are made among RENO, NEOS, and Daya Bay to find a possible spectral variation.Comment: 6 pages, 5 figures: This manuscript has been significantly revised by the joint reanalysis by RENO and NEOS Collaborations. (In the previous edition, the RENO collaboration used publicly available NEOS data to evaluate the expected neutrino spectrum at NEOS.

    Preparation and characterization of starch-poly-epsilon-caprolactone microparticles incorporating bioactive agents for drug delivery and tissue engineering applications

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    One limitation associated with the delivery of bioactive agents concerns the short half-life of these molecules when administered intravenously, which results in their loss from the desired site. Incorporation of bioactive agents into depot vehicles provides a means to increase their persistence at the disease site. Major issues are involved in the development of a proper carrier system able to deliver the correct drug, at the desired dose, place and time. In this work, starch-poly-e-caprolactone (SPCL) microparticles were developed for use in drug delivery and tissue engineering (TE) applications. SPCL microparticles were prepared by using an emulsion solvent extraction/evaporation technique, which was demonstrated to be a successful procedure to obtain particles with a spherical shape (particle size between 5 and 900 lm) and exhibiting different surface morphologies. Their chemical structure was confirmed by Fourier transform infrared spectroscopy. To evaluate the potential of the developed microparticles as a drug delivery system, dexamethasone (DEX) was used as model drug. DEX, a well-known component of osteogenic differentiation media, was entrapped into SPCL microparticles at different percentages up to 93%. The encapsulation efficiency was found to be dependent on the polymer concentration and drug-to-polymer ratio. The initial DEX release seems to be governed mainly by diffusion, and it is expected that the remaining DEX will be released when the polymeric matrix starts to degrade. In this work it was demonstrated that SPCL microparticles containing DEX can be successfully prepared and that these microparticular systems seem to be quite promising for controlled release applications, namely as carriers of important differentiation agents in TE.E.R.B. thanks the Marie Curie Host Fellowships for Early Stage Research Training (EST) "Alea Jacta EST" (MEST-CT-2004-008104) for providing her with a PhD Fellowship. This work was partially supported by the European NoE EXPERTISSUES (NMP3-CT-2004-500283)
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