252 research outputs found

    Implications of the measurements of B_s - B_s bar mixing on SUSY models

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    We derive constraints on the mass insertion parameters from the recent measurements of B_s - B_s bar mixing, and discuss their implications on SUSY breaking mediation mechanisms and SUSY flavor models. Some SUSY flavor models are already excluded or disfavored by B_s - B_s bar mixing. We also discuss how to test the SM and SUSY models in the future experiments, by studying other CP violating observables related to b -> s transition, such as the time-dependent CP asymmetry in B -> phi K_S and the direct CP asymmetry in B -> X_s gamma.Comment: 29 page

    Sflavor mixing map viewed from a high scale in supersymmetric SU(5)

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    We study flavor violation in a supersymmetric SU(5) grand unification scenario in a model-independent way employing mass insertions. We examine how the quark and the lepton sector observables restrict sfermion mixings. With a low soft scalar mass, a lepton flavor violating process provides a stringent constraint on the flavor structure of right-handed down-type squarks. In particular, mu -> e gamma turns out to be highly susceptible to the 1-3 and 2-3 mixings thereof, due to the radiative correction from the top Yukawa coupling to the scalar mass terms of 10. With a higher scalar mass around the optimal value, in contrast, the quark sector inputs such as B-meson mixings and hadron electric dipole moment, essentially determine the room for sfermion mixing. We also discuss the recent deviation observed in B_s mixing phase, projected sensitivity of forthcoming experiments, and ways to maintain the power of leptonic restrictions even after incorporating a solution to fix the incorrect quark-lepton mass relations.Comment: 40 pages, updated using phi_s from HFAG, conclusion unchange

    B0 - B0 bar mixing, B -> J/psi K_S and B -> X_d gamma in general MSSM

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    We consider the gluino-mediated SUSY contributions to B0 - B0 bar mixing, B -> J/psi K_S and B -> X_d gamma in the mass insertion approximation. We find the LL mixing parameter can be as large as |delta_{13}^d_{LL}| < 2*10^-1, but the LR mixing is strongly constrained by the B -> X_d gamma branching ratio and we find |delta_{13}^d_{LR}| < 10^-2. The implications for the direct CP asymmetry in B -> X_d gamma and the dilepton charge asymmetry (A_{ll}) are also discussed, where substantial deviations from the standard model predictions are possible.Comment: 14 pages, 4 figure

    Chiral perturbation theory for pentaquark baryons and its applications

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    We construct a chiral lagrangian for pentaquark baryons assuming that the recently found Theta^+ (1540) state belongs to an antidecuplet of SU(3) flavor symmetry with J^P = (1/2)^(+-). We derive the Gell-Mann-Okubo formulae for the antidecuplet baryon masses, and a possible mixing between the antidecuplet and the pentaquark octet. Then we calculate the cross sections for pi^- p -> K^- Theta^+ and gamma n -> K^- Theta^+ using our chiral lagrangian. The resulting amplitudes respect the underlying chiral symmetry of QCD correctly. We also describe how to include the light vector mesons in the chiral lagrangian.Comment: 4 page

    Lepton masses and mixing angles from heterotic orbifold models

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    We systematically study the possibility for realizing realistic values of lepton mass ratios and mixing angles by using only renormalizable Yukawa couplings derived from heterotic Z6Z_6-I orbifold. We assume one pair of up and down sector Higgs fields. We consider both the Dirac neutrino mass scenario and the seesaw scenario with degenerate right-handed majorana neutrino masses. It is found that realistic values of the charged lepton mass ratios, me/mτm_e/m_\tau and mμ/mτm_\mu/m_\tau, the neutrino mass squared difference ratio, Δm312/Δm212\Delta m^2_{31}/\Delta m^2_{21}, and the lepton mixing angles can be obtained in certain cases.Comment: 22 pages, late

    Supernova Axion Emissivity with Δ(1232)\Delta(1232) Resonance in Heavy Baryon Chiral Perturbation Theory

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    In this paper, we evaluate the energy loss rate of supernovae induced by the axion emission process π+pn+a\pi^- + p \to n + a with the Δ(1232)\Delta(1232) resonance in the heavy baryon chiral perturbation theory for the first time. Given the axion-nucleon-Δ\Delta interactions, we include the previously ignored Δ\Delta-mediated graphs to the π+pn+a\pi^- + p \to n + a process. In particular, the Δ0\Delta^0-mediated diagram can give a resonance contribution to the supernova axion emission rate when the center-of-mass energy of the pion and proton approaches the Δ(1232)\Delta(1232) mass. With these new contributions, we find that for the typical supernova temperatures, compared with the earlier work with the axion-nucleon (and axion-pion-nucleon contact) interactions, the supernova axion emissivity can be enhanced by a factor of \sim4(2) in the Kim-Shifman-Vainshtein-Zakharov model and up to a factor of \sim5(2) in the Dine-Fischler-Srednicki-Zhitnitsky model with small tanβ\tan\beta values. Remarkably, we notice that the Δ(1232)\Delta(1232) resonance gives a destructive contribution to the supernova axion emission rate at high supernova temperatures, which is a nontrivial result in this study.Comment: 17 pages, 4 figures, typo is fixed, references updated. Matches version published in Physical Review
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