Search for Nucleon and Dinucleon Decays with an Invisible Particle and a Charged Lepton in the Final State at the Super-Kamiokande Experiment

Search results for nucleon decays p -> e(+)X, p -> mu X+, n -> nu gamma (where X is an invisible, massless particle) as well as dinucleon decays np -> e(+)nu, np -> mu(+)nu, and np -> tau(+)nu in the Super-Kamiokande experiment are presented. Using single-ring data from an exposure of 273.4 kton . yr, a search for these decays yields a result consistent with no signal. Accordingly, lower limits on the partial lifetimes of tau(p -> e+X) > 7.9 x 10(32) yr, tau(p ->mu+X) > 4.1 x 10(32) yr, tau(n ->nu gamma) > 5.5 x 10(32) yr, tau(np -> e+mu) > 2.6 x 10(32) yr, tau(np ->mu+nu) > 2.2 x 10(32) yr, and tau(np ->tau+nu) > 2.9 x 10(31) yr at a 90% confidence level are obtained. Some of these searches are novel.