Proton decay into light new particles

Light new particles could be emitted in nucleon decays if they have baryon-number-violating couplings. Even though they usually leave the detector as missing energy, interesting signatures can arise in such decays in underground detectors such as Super-Kamiokande and DUNE. In the particularly simple case of light sterile neutrinos, nucleon decays can even be an efficient production mechanism that leads to characteristic displaced decay signatures.