Visible neutrino decay in the light of appearance long baseline experiments

Joel Jonas Perez

 

We investigate the present constraints from the T2K experiment for the neutrino decay scenario induced by non-diagonal couplings of Majorons to neutrinos. As novelty, on top of the typical invisible decay prescription, we add the contribution of visible decay, where final products can be observed. This new effect depends on the nature of the neutrino - Majoron coupling, which can be of scalar or pseudoscalar type. Using the combination of disappearance and appearance data from T2K we constrain the decay parameter for the heaviest neutrino, for normal ordering. We find that when considering visible decay within appearance data, one can improve current neutrino long baseline constraints by one order of magnitude compared to previous bounds.