Measurement of branching fractions for $ψ(3686)\rightarrowγη',γη$ and $γπ^{0}$

Abstract

Using a data sample of $448\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII storage ring, the decays $ψ(3686)\rightarrowγη$ and $ψ(3686)\rightarrowγπ^{0}$ are observed with a statistical significance of $7.3σ$ and $ 6.7σ$, respectively. The branching fractions are measured to be $\mathcal{B}(ψ(3686)\rightarrowγη)=(0.85\pm0.18\pm0.05)\times10^{-6}$ and $\mathcal{B}(ψ(3686)\rightarrowγπ^{0})=(0.95\pm0.16\pm0.05)\times10^{-6}$. In addition, we measure the branching fraction of $ψ(3686)\rightarrowγη'$ to be $\mathcal{B}(ψ(3686)\rightarrowγη')=(125.1\pm2.2\pm6.2)\times 10^{-6}$, with improved precision compared to previous results.