Search for proton decay via $p\rightarrow \mu^+K^0$ in 0.37 megaton-years exposure of Super-Kamiokande

TL;DR

This study conducted a comprehensive search for proton decay into a muon and neutral kaon using extensive data from Super-Kamiokande, setting new lower limits on proton lifetime with improved analysis techniques.

Contribution

The paper presents the first search for $p ooxed{ ext{μ}^+K^0}$ decay in 0.37 Mton·years of data, extending previous limits with enhanced event reconstruction.

Findings

No significant proton decay events observed.

Set a lower limit of 3.6×10^{33} years on proton lifetime.

Extended previous search by 0.2 Mton·years of data.

Abstract

We searched for proton decay via $p\to\mu^+K^0$ 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 $K^0_S$ and $K^0_L$ 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 $3.6\times10^{33}$ years on the proton lifetime.