Exploration of physics beyond the standard model through flavor physics

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1. Study of flavor physics in supersymmetric modelsSupersymmetry is considered to be a promising candidate of new physics at the TeV scale, and search for supersymmetric particles is a main target of LHC experiments. If supersymmetric particles are discovered there, flavor physics will play an important role in probing theory at the GUT and/or the seesaw neutrino scale. We have calculated various physical observable quantities in B decays, K decays and lepton flavor violation processes for several supersymmetric models, and have illustrated how we can distinguish different models by comparing flavor signals. We have also calculated branching ratios of tauonic decays and semi tauonic decays of B mesons in supersymmetric models and show synergy between measurements of these quantities and charged Higgs boson search at LHC.2. lepton flavor violation in the left-right symmetric modelSmall masses of neutrinos provide an important clue to possible physics beyond the standard model. In particular, if the origin of the neutrino mass generation exists at the ay scale, we can anticipate new particle discovery at the LHC as well as large enhancement of lepton flavor violation processes. As an example of such a scenario, we study relationship between tau and muon lepton flavor violation processes and neutrino mass generation mechanism in the left-right symmetric model.3. little Higgs model and dark matterIt is pointed out that the recently proposed little Higgs model can accommodate a dark matter particle if the model is extended with the T-parity. We have studied phenomenological constraints and dark matter relic abundance in this model, and have investigated a possibility of detecting cosmic positron signals from the pair annihilation of dark matter particles in our galaxy under these constraints.