523 research outputs found

    Effect of neutrino trapping on the three flavor FFLO phase of QCD

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    We compute the effect of a non-zero lepton chemical potential on the structure of the three flavor Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase of QCD at finite temperature. We show that, as in the BCS case, the lepton chemical potential favors two-species color superconductivity and disfavors the three species pairing. We stress that this study could be relevant for the cooling of a proto-neutron star with a FFLO core, if the temperatures are higher than the un-trapping temperature.Comment: 12 pages, 2 figures, RevTeX4 class. Changed Fig. 2 (see text) and some reference adde

    Semileptonic decays in the limit of a heavy daughter quark

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    The rate of the semileptonic decay b to c l v is calculated with order alphas^2 accuracy, as an expansion around the limit of equal masses of the b and c quarks. Recent results obtained around the limit of the c-quark much lighter than b are confirmed. Details of the new expansion method are described.Comment: 7 pages, 5 figure

    Semi-Leptonic b-decay at Intermediate Recoil

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    We compute the O(\alpha_s^2) corrections to the differential rate of the semileptonic decay b -> clv at the "intermediate recoil" point, where the c-quark mass and the invariant mass of the leptons are equal. The calculation is based on an expansion around two opposite limits of the quark masses m_{b,c}: m_c ~ m_b and m_c << m_b. The former case was previously studied; we correct and extend that result. The latter case is new. The smooth matching of both expansions provides a check of both. We clarify the discrepancy between the recent determinations of the full NNLO QCD correction to the semileptonic b -> c rate, and its earlier estimate.Comment: 9 pages, 6 figures, Replaced figures, small format and typo corrections, added appendix and reference

    Electroweak Fermion-loop Contributions to the Muon Anomalous Magnetic Moment

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    The two-loop electroweak corrections to the anomalous magnetic moment of the muon, generated by fermionic loops, are calculated. An interesting role of the top quark in the anomaly cancellation is observed. New corrections, including terms of order Gμαmt2G_\mu \alpha m_t^2, are computed and a class of diagrams previously thought to vanish are found to be important. The total fermionic correction is −(23±3)×10−11-(23\pm 3) \times 10^{-11} which decreases the electroweak effects on g−2g-2, predicted from one-loop calculations, by 12\%. We give an updated theoretical prediction for g−2g-2 of the muon.Comment: Corrected versio

    Vibrationally resolved NO dissociative excitation cross sections by electron impact

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    A theoretical investigation of the dissociative excitation by electron impact on the NO molecule is presented, aiming to make up for the lack of data for this process in the literature. A full set of vibrationally-resolved cross sections and corresponding rate coefficients are calculated using the Local-Complex-Potential approach and five resonant states of NO^-.Comment: 5 pages, 3 figure
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