Dinucleon and Nucleon Decay to Two-Body Final States with no Hadrons in Super-Kamiokande

Using 0.37 megaton$\cdot$years of exposure from the Super-Kamiokandedetector, we search for 10 dinucleon and nucleondecay modes that have a two-body final state with no hadrons. These baryon and lepton numberviolating modes have the potential to probe theories of unification and baryogenesis. For five of these modes the searches are novel, and for the other five modes we improve the limits by more than one order of magnitude. No significant evidence for dinucleon or nucleondecay is observed and we set lower limits on the partial lifetime of oxygen nuclei and on the nucleonpartial lifetime that are above $4\times 10^{33}$ years for oxygen via the dinucleon decay modes and up to about $4 \times 10^{34}$ years for nucleonsvia the single nucleondecay modes.