Measurement of the branching fraction for ψ (3770)→ γχ c 0

By analyzing a data set of 2.92 fb−1 of e+e− collision data taken at s=3.773 GeV and 106.41×106 ψ(3686) decays taken at s=3.686 GeV with the BESIII detector at the BEPCII collider, we measure the branching fraction and the partial decay width for ψ(3770)→γχc0 to be B(ψ(3770)→γχc0)=(6.88±0.28±0.67)×10−3 and Γ[ψ(3770)→γχc0]=(187±8±19) keV , respectively. These are the most precise measurements to date.