Active-active and active-sterile neutrino oscillation solutions to the atmospheric neutrino anomaly

Gonzalez-Garcia, M. C.; Nunokawa, H.; Peres, O. L. G.; Valle, J. W. F.

Active-active and active-sterile neutrino oscillation solutions to the atmospheric neutrino anomaly

Authors

Gonzalez-Garcia, M. C.

Nunokawa, H.

Peres, O. L. G.

Valle, J. W. F.

Description

We perform a fit to the full data set corresponding to 33.3 kt-yr of data of the Super-Kamiokande experiment as well as to all other experiments in order to compare the two most likely solutions to the atmospheric neutrino anomaly in terms of oscillations in the $ν_μ\to ν_τ$ and $ν_μ\to ν_s$ channels. Using state-of-the-art atmospheric neutrino fluxes we have determined the allowed regions of oscillation parameters for both channels. We find that the $Δm^2$ values for the active-sterile oscillations (both for positive and negative $Δm^2$) are higher than for the $ν_μ\to ν_τ$ case, and that the increased Super-Kamiokande sample slightly favours $ν_μ\to ν_τ$ oscillations over oscillations into a sterile species $ν_s$, $ν_μ\to ν_s$, and disfavours $ν_μ\to ν_e$. We also give the zenith angle distributions predicted for the best fit points in each of the possible oscillation channels. Finally we compare our determinations of the atmospheric neutrino oscillation parameters with the expected sensitivities of future long-baseline experiments K2K, MINOS, ICARUS, OPERA and NOE.
Updated to 535 days of Super-Kamiokande and corresponding modifications in the discussion and figures. Some References added