Experimental study of the decay $K_L^0\to\pi^0\nu\bar{\nu}$

TL;DR

This paper reports the first dedicated experimental search for the rare decay of neutral kaons into a neutral pion and neutrinos, setting an upper limit on its branching ratio.

Contribution

It presents the first dedicated experimental upper limit on the decay $K_L^0 o ext{pi}^0 uar{ u}$, advancing the search for rare kaon decays.

Findings

Upper limit of 2.6 x 10^{-8} on the decay branching ratio

First dedicated search for this rare decay

Experimental constraints on new physics models

Abstract

The first dedicated search for the rare neutral-kaon decay $K_L^0\to\pi^0\nu\bar{\nu}$ has been carried out in the E391a experiment at the KEK 12-GeV proton synchrotron. The final upper limit of 2.6 $\times 10^{-8}$ at the 90% confidence level was set on the branching ratio for the decay.