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

Abstract

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

5 pages, 5 eps figures, submitted to PRL