Atmospheric neutrino oscillation analysis with sub-leading effects in Super-Kamiokande I, II, and III

TL;DR

This study analyzes atmospheric neutrino data from Super-Kamiokande I, II, and III to search for signs of non-zero theta_{13} and deviations in theta_{23}, finding no significant evidence but constraining the parameters within certain limits.

Contribution

First comprehensive analysis incorporating sub-leading effects in atmospheric neutrino oscillations across multiple Super-Kamiokande phases.

Findings

No evidence for non-zero theta_{13}

Constraints on sin^2 theta_{13} and Delta m^2

Atmospheric mixing angle within 0.407 to 0.583 at 90% C.L.

Abstract

We present a search for non-zero theta_{13} and deviations of sin^2 theta_{23} from 0.5 in the oscillations of atmospheric neutrino data from Super-Kamiokande -I, -II, and -III. No distortions of the neutrino flux consistent with non-zero theta_{13} are found and both neutrino mass hierarchy hypotheses are in agreement with the data. The data are best fit at Delta m^2 = 2.1 x 10^-3 eV^2, sin^2 theta_{13} = 0.0, and sin^2 theta_{23} =0.5. In the normal (inverted) hierarchy theta_{13} and Delta m^2 are constrained at the one-dimensional 90% C.L. to sin^2 theta_{13} < 0.04 (0.09) and 1.9 (1.7) x 10^-3 < Delta m^2 < 2.6 (2.7) x 10^-3 eV^2. The atmospheric mixing angle is within 0.407 <= sin^2 theta_{23} <= 0.583 at 90% C.L.