Browsing by Author "Ota, Toshihiko"

Now showing 1 - 3 of 3
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    CP violation due to multi Froggatt-Nielsen fields
    (2007-05-15T12:00:46Z) Kanemura, Shinya; Matsuda, Koichi; Ota, Toshihiko; Petcov, Serguey T.; Shindou, Tetsuo; Takasugi, Eiichi; Physics; Elementary Particle Theory
    We study how to incorporate CP violation in the Froggatt--Nielsen (FN) mechanism. To this end, we introduce non-renormalizable interactions with a flavor democratic structure to the fermion mass generation sector. It is found that at least two iso-singlet scalar fields with imposed a discrete symmetry are necessary to generate CP violation due to the appearance of the relative phase between their vacuum expectation values.
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    Enhancement of lepton flavor violation in a model with bi-maximal mixing at the grand unification scale
    (2005) Kanemura, Shinya; Matsuda, Koichi; Ota, Toshihiko; Shindou, Tetsuo; Takasugi, Eiichi; Tsumura, Koji; Physics; Elementary Particle Theory
    We study phenomenological predictions in the scenario with the quasi-degenerate relation among neutrino Dirac masses, m_D1 simeq m_D2 < m_D3, assuming the bi-maximal mixing at the grand unification scale in supersymmetric standard models with right-handed neutrinos. A sufficient lepton number asymmetry can be produced for successful leptogenesis. The lepton flavor violating process mu to e gamma can be enhanced due to the Majorana phase, so that it can be detectable at forthcoming experiments. The processes tau to e gamma and tau to mu gamma are suppressed because of the structure of neutrino Dirac masses, and their branching ratios are smaller than that of mu to e gamma.
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    Phase effects from the general neutrino Yukawa matrix on lepton flavor violation
    (2005) Kanemura, Shinya; Matsuda, Koichi; Ota, Toshihiko; Shindou, Tetsuo; Takasugi, Eiichi; Tsumura, Koji; Physics; Elementary Particle Theory
    We examine contributions from Majorana phases to lepton flavor violating processes in the framework of the minimal supersymmetric standard model with heavy right-handed neutrinos. All phases in the complex neutrino Yukawa matrix are taken into account in our study.