11,657 research outputs found

    A Global Treatment Of VMD Physics Up To The ϕ\phi: I. e+ee^+e^- Annihilations, Anomalies And Vector Meson Partial Widths

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    The HLS Model, equipped with a mechanism providing the breaking of U(3)/SU(3) symmetry and an isospin symmetry breaking leading naturally to vector meson mixing, has been recently shown to successfully account for e^+ e^- \ra \pi^+\pi^- cross section and for the dipion spectrum in τ\tau decay. The present study shows that the full anomalous sector of the HLS model can be considered and is validated by the experimental data. Indeed, this extended model provides a successful simultaneous fit to the e^+ e^- \ra \pi^+\pi^- data together with the available data on e^+ e^- \ra \pi^0\gamma, e^+ e^- \ra \eta\gamma and e^+ e^- \ra \pi^0 \pi^+\pi^- cross sections. It is shown that the fit of these data sets also predicts an accurate description of the \eta/\eta^\prime \ra \pi^+ \pi^- \gamma decays fully consistent with the reported information on their branching fractions and spectra. Finally, one also derives from our global fits products of widths of the form \Gamma (V \ra f_1)\Gamma(V \ra e^+ e^-) and ratios of the form \Gamma (V \ra f_1)/\Gamma (V \ra f_2) describing decays of vector mesons to several non--leptonic final states.Comment: 58 pages, 10 figures Corrected a few misprints. Footnote 10 change

    Mars surface transportation options

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    As the number of scientific experiments for the surface of Mars grows, the need for effective surface transportation becomes critical. Because of the diversity of the experiments proposed, as well as the desire to explore Mars from the equator to the poles, the optimum surface vehicle configuration is not obvious. Five candidate vehicles are described, with an estimate of their size and performance. In order to maximize the success of a manned Mars mission, it appears that two vehicles should be designed for surface transportation: an advanced long-range rover, and a remotely-piloted airplane

    The Business Cycle in the Philippines

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    This paper provides an overall picture of the Philippine business cycles covering the period 1981 to 2003 by characterizing them in terms of volatility, co-movement and persistence. As a trend-cycle decomposition technique, the most frequently used Hodrick Prescott filter was applied. The period under investigation brought about three cycles: 1983-1989, 1989-1997 and 1997-2000 with initially very erratic but over time smoother fluctuations. In resemblance with industrialized countries, investment turns out to be the most volatile and consumption the least volatile national expenditure component, potentially pointing at Keynes assertion of animal spirits of investors as the source for the former phenomenon. Further, with the exception of prices, inflation and the terms of trade, all variables have strong and positive correlations with GDP. The strong negative price-output correlation, and the weak positive inflation-output correlation identify supply shocks as the triggering factor for observed business cycles, pointing at either technological change or drastic changes in the weather as possible spurring factors. Moreover, the investigation clearly reveals procyclical fiscal and monetary policy interventions, contradicting theoretical prescriptions of countercyclical stabilization policies to swiftly overcome economic recessions. Finally, all key macroeconomic variables show fairly low persistence, substantiating the Philippines popularity for its boom-bust cycles

    Neutrino-induced coherent pion production off nuclei reexamined

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    It is pointed out that so far all theoretical estimates of coherent pion production off nuclei induced by neutrinos rely on the 'local approximation' well known in photonuclear physics. The effects of dropping this approximation are discussed. It is found that in a plane wave approximation for the pion the local approximation overestimates the coherent neutrino-induced pion production on nuclei.Comment: v3: comments on pion FSI added, minor corrections; version as published in Phys. Rev.

    Reduced Density Matrix Approach to Phononic Dissipation in Friction

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    Understanding mechanisms for energy dissipation from nanoparticles in contact with large samples is a central problem in describing friction microscopically. Calculation of the reduced density matrix appears to be the most suitable metho to study such systems that are coupled to a large environment. In this paper the time evolution of the reduced density matrix has been evaluated for an arbitrary system coupled to a heat reservoir. The formalism is then applied to study the vibrational relaxation following the stick-slip motion of a small adsorbate on a surface. The frequency dependence of the relaxation time is also determined.Comment: 16 pages, 3 figures (included), revte

    Social marketing: Immunizing against unethical practice

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    A simple approach for the catalytic conversion of primary alcohols into their corresponding esters and amides, with evolution of H2 gas using in situ formed ruthenium PNP- and PNN-pincer catalysts, is presented. The evaluation showed conversions for the esterification with turnover numbers as high as 4300, and 4400 for the amidation
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