Search for the decay $K_S \to \pi^0\gamma\gamma$

TL;DR

This paper reports a search for the rare decay $K_S o \pi^0\gamma\gamma$ using CERN data, setting an upper limit on its branching ratio, which constrains theoretical models of kaon decays.

Contribution

First experimental search for the decay $K_S o \pi^0\gamma\gamma$ with an upper limit on its branching ratio at 90% confidence level.

Findings

Upper limit for $BR(K_S o\pi^0\gamma\gamma)$ is $3.3 imes 10^{-7}$

Data collected during a 40-hour run at CERN SPS

Constraints on theoretical models of kaon decay processes

Abstract

A search for the decay $K_S\to\pi^0\gamma\gamma$ has been made using the NA48 detector at the CERN SPS. Using data collected in 1999 during a 40-hour run with a high-intensity $K_S$ beam, an upper limit for the branching ratio $BR(K_S\to\pi^0\gamma\gamma, z\ge 0.2)<3.3\times\nolinebreak 10^{-7}$ has been obtained at 90% confidence level, where $z=m_{\gamma\gamma}^2/m_{K_0}^2$.