Search forKL→π0γγ

Abstract

A search for the rare decay mode $K_L$→${\pi }^0$γγ was performed using a data set from Fermilab experiment E-731. The decay is of interest in the context of chiral perturbation theory and for its contribution to the decay $K_L$→${\pi }^0$ $e^{+}$ $e^{\mathrm{-}}$. The result is B($K_L$→${\pi }^0$γγ)<2.7 ×${10}^{\mathrm{-}6}$ (90% confidence level) which is nearly a two-order-of magnitude improvement over the previous best limit.