Search for the radiative decay η→π0γγ in the SND experiment at VEPP-2M

Abstract The η → π 0 γγ decay was investigated by the SND detector at VEPP-2M e + e − collider in the reaction e + e − → φ → ηγ . Here we present the results and some details of this study. We report an upper limit (90% c.l.) Br( η → π 0 γγ ) −4 as our final result. Our upper limit does not contradict the earlier measurement by GAMS spectrometer. To facilitate future studies a rather detailed review of the problem is also given.