91,834 research outputs found

    Laboratory requirements for in-situ and remote sensing of suspended material

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    Recommendations for laboratory and in-situ measurements required for remote sensing of suspended material are presented. This study investigates the properties of the suspended materials, factors influencing the upwelling radiance, and the various types of remote sensing techniques. Calibration and correlation procedures are given to obtain the accuracy necessary to quantify the suspended materials by remote sensing. In addition, the report presents a survey of the national need for sediment data, the agencies that deal with and require the data of suspended sediment, and a summary of some recent findings of sediment measurements

    Possibly New Charmed Baryon States from Bˉ0ppˉD0\bar B^0\to p\bar p D^{0} Decay

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    We examine the invariant mass spectrum of D0pD^{0}p in Bˉ0ppˉD0\bar B^0\to p\bar p D^{0} decay measured by BABAR and find that through the 2-step processes of Bˉ0Bc+(D0p)pˉ\bar B^0\to {\bf B_c^+}(\to D^{0} p)\bar p, where Bc{\bf B_c} denotes a charmed baryon state, some of the peaks can be identified with the established Σc(2800)+\Sigma_c(2800)^+, Λc(2880)+\Lambda_c(2880)^+ and Λc(2940)+\Lambda_c(2940)^+. Moreover, in order to account for the measured spectrum, it is necessary to introduce a new charmed baryon resonance with (m,Γ)=(3212±20,167±34)(m,\,\Gamma)=(3212\pm 20,\,167\pm 34) MeV.Comment: 8 pages, 1 figure, title changed and discussions updated, version accepted for publication in Phys. Rev.

    Long-term X-ray emission from Swift J1644+57

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    The X-ray emission from Swift J1644+57 is not steadily decreasing instead it shows multiple pulses with declining amplitudes. We model the pulses as reverse shocks from collisions between the late ejected shells and the externally shocked material, which is decelerated while sweeping the ambient medium. The peak of each pulse is taken as the maximum emission of each reverse shock. With a proper set of parameters, the envelope of peaks in the light curve as well as the spectrum can be modelled nicely.Comment: 6 pages, 2 figures, accepted for publication in MNRA

    Interacting Individuals Leading to Zipf's Law

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    We present a general approach to explain the Zipf's law of city distribution. If the simplest interaction (pairwise) is assumed, individuals tend to form cities in agreement with the well-known statisticsComment: 4 pages 2 figure

    Inclusive Decays of Bottom Hadrons in New Formulation of Heavy Quark Effective Field Theory

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    We apply the new formulation of heavy quark effective field theory (HQEFT) to the inclusive decays of bottom hadrons. The long-term ambiguity of using heavy quark mass or heavy hadron mass for inclusive decays is clarified within the framework of the new formulation of HQEFT. The 1/mb1/m_b order corrections are absent and contributions from 1/mb21/m_b^2 terms are calculated in detail. This enables us to reliably extract the important CKM matrix element Vcb|V_{cb}| from the inclusive semileptonic decay rates. The resulting lifetime ratios τ(Bs0)/τ(B0)\tau(B^0_s)/\tau(B^0) and τ(Λb)/τ(B0)\tau(\Lambda_b)/\tau(B^0) are found to well agree with the experimental data. We also calculate in detail the inclusive semileptonic branching ratios and the ratios of the τ\tau and β\beta decay rates as well as the charm countings in the B0B^0, Bs0B^0_s and Λb\Lambda_b systems. For B0B^0 decays, all the observables are found to be consistent with the experimental data. More precise data for the B0B^0 decays and further experimental measurements for the Bs0B^0_s and Λb\Lambda_b systems will be very useful for testing the framework of new formulation of HQEFT at the level of higher order corrections.Comment: 20 pages, RevTex, 8 figures, 3 tables, revised version with `dressed heavy quark' being addressed, to be published in Int. J. Mod. Phys.
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