Search for proton decay through p->\barν K^+ in a large water Cherenkov detector

Abstract

We present results of a search for proton decays, $p \to \barν K^+$, using data from a 33 kton$\cdot$year exposure of the Super-Kamiokande detector. Two decay modes of the kaon, $K^+ \to μ^+ ν_μ$ and $K^+ \to π^+ π^0$, were studied. The data were consistent with the background expected from atmospheric neutrinos; therefore a lower limit on the partial lifetime of the proton $τ/ B(p \to \barν K^+)$ was found to be $6.7 \times 10^{32}$ years at 90% confidence level.