Search for Proton Decay via p -> e^+ pi^0 and p -> mu^+ pi^0 in a Large Water Cherenkov Detector

Understand

We have searched for proton decays via p -> e^+ pi^0 and p -> mu^+ pi^0 using data from a 91.7 kiloton year exposure of Super-Kamiokande-I and a 49.2 kiloton year exposure of Super-Kamiokande-II.

• No candidate events were observed with expected backgrounds induced by atmospheric neutrinos of 0.3 events for each decay mode.
• From these results, we set lower limits on the partial lifetime of 8.2$\times10^{33}$ and 6.6$\times10^{33}$ years at 90% confidence level for p -> e^+ pi^0 and p -> mu^+ pi^0 modes, respectively.