Full three flavor oscillation analysis of atmospheric neutrino data observed in Super-Kamiokande

This thesis presents the first-time neutrino oscillation studies considering entire oscillation parameters, two mass differences ∆m 2 12, ∆m2 23, three mixing angles θ12, θ23, θ13, and one CP phase parameter (δcp), by the atmospheric neutrino data observed in Super-Kamiokande. The Super-Kamiokande, a 50 kt water Cherenkov detector, started taking data in 1996 and has been observed a large number of atmospheric neutrino events. About 3,000 day neutrino data is collected through the data taking phases, Super-Kamiokande-I, II and III. This analysis is performed using the amount of this data for the first time. The neutrino data selection and observed data quality for the analysis are summarized in this thesis. The analysis examines for both the normal and inverted mass hierarchy cases. In the normal (inverted) mass hierarchy case, ∆m 2 23, sin2 θ23 and sin 2 θ13 are constrained at 90 % C.L. to 1.88 (1.98) ×10 −3 < ∆m 2 23 < 2.75 (2.81) ×10−3 eV 2, 0.406 (0.426) < sin 2 θ23 < 0.629 (0.644), sin 2 θ31 < 0.066 (0.122). No significant constraint on CP phase at 90 % C.L. is obtained for both mass hierarchies and there is no clear preference of mass hierarchy. * * ACKNOWLEDGMENTS ** First of all, I would like to express my gratitude to Prof. Takaaki Kajita for giving me the excellent opportunity of studying atmospheric neutrino. I have learnt a lot of things and gained