Observation of the doubly radiative decay ${\eta }^{\prime }\to \gamma \gamma {\pi }^0$

BESIII Collaboration, M. Ablikim, M. N. Achasov +426

Based on a sample of $1.31$ billion $J/\psi$ events collected with the BESIII detector, we report the study of the doubly radiative decay ${\eta }^{\prime }\to \gamma \gamma {\pi }^0$ for the first time, where…