Annihilation signatures of neutron dark decay models in neutron oscillation and proton decay searches

A bstract We point out that two models that reconcile the neutron lifetime anomaly via dark decays of the neutron, also predict dark matter-neutron ( χ ¯ − n ) annihilation that may be observable in neutron-antineutron oscillation and proton decay searches at Super-Kamiokande, Hyper-Kamiokande and DUNE. We study signatures of χ ¯ n → γπ 0 (or multi- π 0 ) and χ ¯ n → ϕγπ 0 (or ϕ +multi- π 0 ), where ϕ is an almost massless boson in one of the two models.