Status of Oscillation plus Decay of Atmospheric and Long-Baseline Neutrinos

We study the interplay of neutrino oscillation and invisible decay in atmospheric and long-baseline neutrinos experiments. We perform a global analysis of the full atmospheric data from Super-Kamiokande together with long-baseline K2K and MINOS in these scenarios. We find that the admixture of νμ → ντ oscillations with parameters ∆m232 = 2.6×10 −3 eV and θ23 ∼ 34 ◦ plus decay of the heavy neutrino, ν3, with lifetime of the order τ3/m3 ∼ 2.6× 10 −12 s/eV provides a reasonable fit to atmospheric neutrinos, although this solution becomes more disfavored (dropping to the 99% CL) once long-baseline data are included. Other than this local minimum, the analysis shows no evidence in favor of a non-vanishing neutrino decay width and an lower bound on the decay lifetime τ3/m3 ≥ 9.3 × 10 −11 s/eV is set at 99% CL. In the framework of Majoron models, this constraint can be translated into a bound on the Majoron coupling to ν3 and an unmixed very light sterile state, |gs3| ≤ 8.6 × 10 −3 (2.2 eV/m3).