Observation of the doubly radiative decay η′→ γγπ0 后印本

摘要: Based on a sample of 1.31 billion J/ψ events collected with the BESIII detector, we report the study of the doubly radiative decay η′ → γγπ0 for the first time, where the η′ meson is produced via the J/ψ → γη′ decay. The branching fraction of η′ → γγπ0 inclusive decay is measured to be B(η′ → γγπ0)Incl. = (3.20 ± 0.07(stat) ± 0.23(sys)) × 10−3, while the branching fractions of the dominant process η′ → γω and the nonresonant component are determined to be B(η′ → γω) ×B(ω → γπ0) =(23.7 ± 1.4(stat) ± 1.8(sys)) × 10−4 and B(η′ → γγπ0)NR = (6.16 ± 0.64(stat) ± 0.67(sys)) × 10−4, respectively. In addition, the Mγ2γ -dependent partial widths of the inclusive decay are also presented.