Atmospheric neutrino oscillation analysis with solar terms in Super-Kamiokande

The atmospheric neutrino data have been well explained in the two-flavor νµ ↔ ντ oscillation scheme and the ∆m 2 23 and sin2 2θ23 parameters have been measured. No evidence of the atmospheric νe oscillation has been observed and the mixing angle θ13 is consistent with zero by the results of θ13 search experiments. On the other hand, thanks to the precise measurements by solar neutrino observations and the KamLAND experiment, the LMA-MSW solution of the solar neutrino problem is established and the mixing angle θ12 and mass difference ∆m 2 12 have been measured accurately. If these 1-2 parameters are considered into the atmospheric neutrino oscillation analysis, the oscillation of low energy atmospheric νe might be observed even in case of zero-θ13. The effect of the νe oscillation induced by the 1-2 parameters depends on the octant of θ23 (θ23> 45 ◦ or θ23 < 45 ◦). Therefore the atmospheric neutrino oscillation analysis including the 1-2 parameters has a possibility to determine the octant of θ23 for the non-maximal sin 2 2θ23. This information cannot be obtained by the standard νµ ↔ ντ two-flavor oscillation analysis because the oscillation probability in that framework depends on sin 2 2θ23, not on sin 2 θ23. We have observed large number of atmospheric neutrino events in Super-Kamiokande. In