Contributor info: Mr Ryan Barouki

Ryan Barouki, Giacomo Marocco, Subir Sarkar

SciPost Phys. 13, 118 (2022) · published 28 November 2022 | Toggle abstract · pdf

We revisit the search for heavy neutral leptons with the Big European Bubble Chamber in the 1982 proton beam dump experiment at CERN, focussing on those heavier than the kaon and mixing only with the tau neutrino, as these are far less constrained than their counterparts with smaller mass or other mixings. Recasting the previous search in terms of this model and including additional production and decay channels yields the strongest bounds to date, up to the tau mass. This applies also to our updated bounds on the mixing of heavy neutral leptons with the electron neutrino.