A Model of Neutrino Masses and Mixings and Its Phenomenological Implications
Le, Trinh Thi Ngoc, Physics - Graduate School of Arts and Sciences, University of Virginia
Pham, Hung, Department of Physics, University of Virginia
We present a model of neutrino masses and mixings within the framework of the Electroweak-scale Right-handed neutrino model in which the experimentally desired form of the PMNS matrix is obtained by applying an A(4) symmetry to the Higgs singlet sector responsible for the neutrino Dirac mass matrix. This mechanism naturally avoids potential conflict with the LHC data which severely constrains the Higgs sector, in particular the Higgs doublets. Moreover, by making a simple ansatz we extract charged lepton mass matrix squared for the charged lepton sector. A similar ansatz is proposed for the quark sector in order to construct quark mass matrices. The sources of masses for the neutrinos are entirely different from those for the charged leptons and for the quarks and this might explain why PMNS matrix is very different from CKM matrix. Two interesting phenomenological implications on mu-to-e-gamma and mu-e conversion are investigated within the model. At the limit of zero momentum transfer and large mirror lepton masses, we derive a simple formula to relate the conversion rate with the on-shell radiative decay rate of muon into electron. The Yukawa couplings constrained by current limits and projected sensitivities of these processes are found to be small (of the order of 10e-5 to 10e-3), which give rise to distinct signatures in the search of mirror charged leptons and Majorana right-handed neutrinos at the LHC (or planned colliders).
PHD (Doctor of Philosophy)
Neutrino masses and mixings, Lepton flavor violation, Discrete symmetry, Theoretical particle physics