Upper Limit on the eta to gamma gamma gamma Branching Ratio with the KLOE Detector

TL;DR

This study sets an upper limit on the rare, C-violating decay of eta mesons into three photons using data from the KLOE detector, with no signal observed.

Contribution

First experimental search for eta to gamma gamma gamma decay, establishing a new upper limit on its branching ratio.

Findings

No evidence of eta to gamma gamma gamma decay observed.

Upper limit on branching ratio set at 1.6 x 10^(-5).

Results constrain theoretical models of C-violation in eta decays.

Abstract

We have searched for the C-violating decay eta to gamma gamma gamma in a sample of ~ 18 million eta mesons produced in phi to eta gamma decays, collected with the KLOE detector at the Frascati phi-factory DAFNE. No signal is observed and we obtain the upper limit BR(eta to gamma gamma gamma) less equal than 1.6x10^(-5) at 90 % C.L.