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

Understand

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 nu_mu -> nu_tau oscillations with parameters Delta_m32^2 = 2.6e-3 eV^2 and theta_23 ~ 34 degrees plus decay of the heavy neutrino, nu_3, with lifetime of the order tau_3/m_3 ~ 2.6e-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 tau_3/m_3 > 9.3e-11 s/eV is set at 99% CL.