Special Textures Of The Seesaw Model For The Second Trimaximal Neutrino Mixing And Their Phenomenological Implications

The Standard Model predicts that neutrinos have zero mass,but the discovery of neutrino oscillations suggests that they have non-zero mass.Based on this fact,a reasonable explanation of the neutrino’s mass source is needed.The seesaw mechanism stands out among other mechanisms to explain the origin of neutrino mass.The seesaw mechanism is popular for two reasons:First,it naturally explains the tiny mass of neutrinos.Secondly,it can explain the baryon asymmetry of the Universe through the leptogenesis mechanism.There are three neutrino mixing angles（θ12,θ13 and θ23）.Before the value of θ13 was determined,it was generally believed that it tended to zero.The ideal case of sin θ12=（?）,sin θ23=（?）and θ13=0 is referred to as the tribimaximal（TBM）mixing.However,the Daya Bay experiment finds that the value of θ13 is close to 9°,which means that some modifications must be made to the TBM mixing scheme.One modification is to leave the second column of the TBM mixing matrix intact and the other columns deviate from the value of TBM.Such a mixing matrix is called the second trimaximal neutrino（TM2）mixing.The TM2 mixing is well compatible with the existing experimental data,so it has attracted extensive attention.In this thesis,in the basis of Majorana mass matrix MR being diagonal,we explore the special textures of the Dirac neutrino mass matrix MD that can naturally yield TM2 mixing and check whether its parameters can be further reduced.Our analysis is restricted to the case of there being only one phase parameter which is responsible for both the CP violating effects at low energy and leptogenesis.Our attention is paid to the textures of MD that possess some vanishing or equal elements.On the basis of these results,we further examine if the phase parameter can also take a particular value.We predict the neutrino parameters at χmin2 when the phase also takes a special value,and study the effect of these special conditions on leptogenesis.Subsequently,we present a concrete flavor-symmetry model and realize a representative of them.Finally,the impacts of the renormalization group running effects on the texture of MD and leptogenesis have also been discussed.