Eta-Meson Branching Ratio intoπ0+γ+γ

Abstract

An upper limit of 0.50 (90% confidence level) is set for the branching ratio $\frac{(\eta \to {\pi }^0+\gamma +\gamma )}{(\eta \to \gamma +\gamma )}$ in a spark-chamber experiment measuring ${\pi }^{-}+p\to (n+4\mathrm{}\gamma \mathrm{and} n+2\mathrm{}\gamma )$ at 10 BeV/c. This disagrees with a recent measurement of 0.90±0.10 for the same ratio.