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 Mγγ2-dependent partial widths of the inclusive decay are also presented.
Bibliographical noteFunding Information:
This work is supported in part by National Key Basic Research Program of China under Contract No. 2015CB856700; National Natural Science Foundation of China (NSFC) under Contracts No. 11125525, No. 11235011, No. 11322544, No. 11335008, No. 11335009, No. 11425524, No. 11505111, No. 11635010, No. 11675184; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; the CAS Center for Excellence in Particle Physics (CCEPP) the Collaborative Innovation Center for Particles and Interactions (CICPI) Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts No. U1232201, No. U1332201, No. U1532257, No. U1532258; CAS under Contracts No. KJCX2-YW-N29, No. KJCX2-YW-N45; 100 Talents Program of CAS; National 1000 Talents Program of China; INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology; German Research Foundation DFG under Contracts No. Collaborative Research Center CRC 1044, FOR 2359; Istituto Nazionale di Fisica Nucleare, Italy; Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) under Contract No. 530-4CDP03; Ministry of Development of Turkey under Contract No. DPT2006K-120470; The Swedish Research Council; U.S. Department of Energy under Contracts No. DE-FG02-05ER41374, No. DE-SC-0010118, No. DE-SC-0010504, No. DE-SC-0012069; U.S. National Science Foundation; University of Groningen (RuG) and the Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt; WCU Program of National Research Foundation of Korea under Contract No. R32-2008-000-10155-0.