Phenomenological Study On The Combination Of μ-τ Reflection Symmetry And Texture Zeros In Seesaw Model

Neutrinos are strictly massless in the standard Model.However,the neutrino oscillation experiment led by the Super Kamioka Experiment in Japan has shown that the mass of neutrinos is not zero,and the special properties of neutrino flavor mixing have been discovered along with the continuous development of the neutrino oscillation experiment,which show the incompleteness of the standard model.The advantage of the seesaw mechanism is not only that it can explain the tiny mass of neutrinos more naturally,but also that it provides a new mechanism to explain the asymmetry of matter-antimatter in the universe—Leptogenesis.With the further development of neutrino oscillation experiment and our Daya B ay experiment confirming that θ13 is close to 9° with high confidence,the TBM mixing and μ-τ interchange symmetries established on the basis of sin2 θ12=1/3,sin2 θ23=1/2 and sin2 θ13=0 need to be modified.Therefore,TM1,TM2 mixing and μ-τ reflection symmetries are obtained on the above basis.The above case has attracted wide attention because of its ability to give phenomenological results consistent with experiments and its good effect on reducing the degree of freedom of the neutrino mass model and improving the prediction ability of the model.In this thesis,we first thoroughly study the combination of μ-τ reflection symmetry and texture zeros under the complete seesaw model,so as to further improve the prediction ability of the neutrino mass model:in the basis of the right-handed neutrino mass matrix being diagonal,we impose some texture zeros on the Dirac neutrino mass matrix which respects theμ-τ reflection symmetry,and then study their phenomenological consequences for the neutrino observables and leptogenesis.We found that for MDⅠ,leptogenesis has chance to be successful only when N1 is the lightest right-handed neutrino in the NO case and m1（?）0.01 eV.For MDⅡ,we give the relevant cases in which leptogenesis can be successful for different combinations of（ρ,σ）in the NO（IO）case.Then,we have further performed the study in the scenario that the μ-τ reflection symmetry is combined with the TM1 and TM2 mixings,and fully discuss the phenomenological consequences for the neutrino observables and leptogenesis in this case.We found that leptogenesis has smaller chance to be successful when the μ-τ reflection symmetry is combined with TM2 mixing than when it is combined with TM1 mixing.In combination with TM2 mixing,leptogenesis has chance to be successful only if N1 is the lightest right-handed neutrino in the IO case with ρ=π/2 and for 0.01（?）m₃（?）0.06 eV.Because M_D is more constrained in these cases,it is more predictable.