Abstract

We present the results of searches for nucleon decays via p\rightarrow\nu\pi^{+} and n\rightarrow\nu\pi^{0} using a 0.484 Mt\cdotyr exposure of Super-Kamiokande I-V data covering the entire pure water phase of the experiment. Various improvements on the previous 2014 nucleon decay search, which used an exposure of 0.173 Mt\cdotyr, are incorporated. The physics models related to pion production and nuclear interaction are refined with external data, and a more comprehensive set of systematic uncertainties, now including those associated with the atmospheric neutrino flux and pion production channels is considered. Also, the fiducial volume has been expanded by 21\%. No significant indication of a nucleon decay signal is found beyond the expected background. Lower bounds on the nucleon partial lifetimes are determined to be 3.5\times10^{32}~yr for p\rightarrow\nu\pi^{+} and 1.4\times10^{33}~yr for n\rightarrow\nu\pi^{0} at 90\% confidence level.