Study of the DecayJψ→γηππ

Abstract

The radiative decay $\frac{J}{\psi }\to \gamma \eta \pi \pi$ has been studied with data taken with the crystal-ball detector at the SPEAR $e^{+}{e}^{-}$ storage ring. In addition to the well-known ${\eta }^{\prime }$, the $\eta \pi \pi$ mass spectrum shows a broad enhancement centered at ∼ 1700 MeV. The authors have searched for the $\iota \mathrm{}\left(1440\right)\mathrm{}$ in the $\eta \pi \pi$ mass spectrum and find $\frac{R(\frac{J}{\psi }\to \gamma \iota )(\iota \to \eta \pi \pi )}{R(\frac{J}{\psi }\to \gamma \iota )(\iota \to K\overline{K}\pi )}<0.5\mathrm{}$ (90% confidence level).