New measurement of the rare decay φ→η′γ with CMD-2

Abstract

A new measurement of the rare decay φ → η ′ γ performed with the CMD-2 detector at Novosibirsk is described. Of the data sample corresponding to the integrated luminosity of 14.5 pb −1 , twenty one events have been selected in the mode η ′ → π + π − η, η → γγ. The following branching ratio was obtained:+2.1 −1.9 ± 1.1) · 10 −5 .