Exploring supersymmetry and its breaking with flavor physics

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The minimal supergravity model, the supersymmetric SU(5) grand unified model with right-handed neu- trinos, and a supersymmetric model with U(2) flavor symmetry were studied in order to explore flavor structure of supersymmetry breaking.Several processes relevant for the flavor physics were analyzed in these models. In the・quark sector, we examined the B_d-B_d mixing, the B_3-B_5, mixing, the CP violation in the K^0-K^0 mixing, B_d→φK_s, b→Sγ, and b→dγ. As for the lepton sector, we calculated branching ratios of decay processes such as μ→eγ, τ→μγ, and τ→eγ. We took into account recent experimental results like the neutrino oscillation in our study.Our research unveiled the following facts. The minimal supergravity model exhibits virtually no new flavor phenomena, and the allowed parameter region of this model is tightly constrained, employing the recent experimental result on the B^s-R^s mixing in addition to other experimental bounds. Substantial deviations from the standard model are possible in the supersymmetric SU(5) grand unified model. with right-handed neutrinos, if the right-handed neutrinos are not degenerated. Moreover, flavor signals in the lepton sector show several patterns in this model, depending on the mixing in the scalar lepton sector. As for the supersymmetric model with U(2) flavor symmetry, though flavor signals may significantly differ from the standard model, the prediction of the model is heavily contingent on details of the model.In addition to the above study, we carried out researches concerning effects of the charged Higgs boson on the semitauonic B decay and implications of the neutrino mixing on the interaction of the cosmic neutrino background with macroscopic matter.