Measurement of branching fractions for $\psi(3686)\rightarrow\gamma\eta',\gamma\eta$ and $\gamma\pi^{0}$

Abstract

Using a data sample of 448×106 ψ(3686) events collected with the BESIII detector operating at the BEPCII storage ring, the decays ψ(3686)→γη and ψ(3686)→γπ0 are observed with a statistical significance of 7.3σ and $ 6.7\sigma$, respectively. The branching fractions are measured to be B(ψ(3686)→γη)=(0.85±0.18±0.05)×10−6 and B(ψ(3686)→γπ0)=(0.95±0.16±0.05)×10−6. In addition, we measure the branching fraction of ψ(3686)→γη′ to be B(ψ(3686)→γη′)=(125.1±2.2±6.2)×10−6 with improved precision compared to previous results.