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 ν_μ → ν_τ oscillations with parameters Δ m₃₂² = 2.6 × 10^-3 eV² 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, | g_{s 3} | ≤ 8.6 × 10^-3   (2.2 eV / m₃).