Search for proton decay via $p\to \hat{I}{¼}^{+}{K}^0$ in 0.37 megaton-years exposure of Super-Kamiokande

Abstract

We searched for proton decay via $p\to \hat{I}{¼}^{+}{K}^0$ in 0.37\,Mton$\cdot$years of data collected between 1996 and 2018 from the Super-Kamiokande water Cherenkov experiment. The selection criteria were defined separately for $K_S^0$ and $K_L^0$ channels. No significant event excess has been observed. As a result of this analysis, which extends the previous search by an additional 0.2\,Mton$\cdot$years of exposure and uses an improved event reconstruction, we set a lower limit of $3.6\times 10^{33}$ years on the proton lifetime.

13 pages, 11 figures