CP Symmetry And Lepton Flavor Mixing

The strategy of constraining the lepton flavor mixing from remnant CP symme-try is investigated in a rather general way.Phenomenological implications for neutrino oscillation experiments,neutrinoless double beta decay experiments as well as leptoge-nesis are discussedThe neutrino mass matrix generally admits four remnant CP transformations.The lepton mixing matrix can be reconstructed from the postulated remnant CP transforma-tions.When one or two remnant CP transformations are preserved,the resulting lepton mixing matrix would depend on three real parameters or one real parameter respec-tively.When all four remnant CP transformations are preserved.The lepton mixing matrix is completely fixed.The concrete form of the mixing matrix is presented.The phenomenological predictions for the mixing parameters are discussed.The conditions leading to vanishing or maximal Dirac CP violation are studied.A classification of generalized C.P symmetries preserved by the neutrino mass ma-trix according to the number of zero entities in the associated transformation matrix is given.We determine the corresponding constrained form of the lepton mixing matrix,characterized by correlations between the mixing angles and the CP violating phases.We compare with the corresponding restrictions from current neutrino oscillation glob-al fits and show that,in some cases,the Dirac CP phase characterizing oscillations is highly constrained.At last,we discuss flavour dependent leptogenesis in the framework of lepton flavour models based on discrete flavour and CP symmetries applied to the type-I see-saw model.Working in the flavour basis,we analyse the cases of one and two general residual CP symmetries in the neutrino sector.We systematically study and classify this two cases for all possible residual CP symmetries,and show that the R-matrix is tightly constrained,leading to possible connections between leptogenesis and PMNS parameters.The formalism is completely general in the sense that the residual CP sym-metries could result from any high energy discrete flavour theory which respects any CP symmetry.