Measurement of the ratio Gamma(K_L -> gamma gamma)/Gamma(K_L -> pi^0 pi^0 pi^0) with the KLOE detector

TL;DR

This paper reports a precise measurement of the ratio of decay rates of K_L mesons into two photons versus three neutral pions, using the KLOE detector at the DAFNE phi-factory, providing improved data for understanding kaon decays.

Contribution

The study provides a new, highly precise measurement of the decay ratio of K_L mesons into gamma gamma and 3 pi^0, utilizing a large data sample and advanced tagging techniques.

Findings

Measured R = (2.79 ± 0.02_stat ± 0.02_syst) × 10^{-3}

Derived BR(K_L -> gamma gamma) = (5.89 ± 0.07 ± 0.08) × 10^{-4}

Enhanced accuracy in kaon decay measurements.

Abstract

We have measured the ratio R=Gamma(K_L -> gamma gamma)/ \Gamma(K_L -> 3 pi^0) using the KLOE detector. From a sample of ~ 10^9 phi-mesons produced at DAFNE, the Frascati phi-factory, we select ~ 1.6 10^8 K_L-mesons tagged by observing K_S -> pi^+ pi^- following the reaction e^+ e^- -> phi -> K_L K_S. From this sample we select 27,375 K_L -> gamma gamma events and obtain R = (2.79 \pm 0.02_{stat} \pm 0.02_{syst}) \times 10^{-3}. Using the world average value for BR(K_{L} -> 3 pi^0), we obtain BR(K_{L} -> gamma gamma) = (5.89 \pm 0.07 \pm 0.08) \times 10^{-4} where the second error is due to the uncertainty on the 3 pi^0 branching fraction.