Ablikim, M.Achasov, M. N.Adlarson, P.Ai, X. C.Aliberti, R.Amoroso, A.Çetin, Serkant Ali2024-05-192024-05-1920232470-00102470-0029https://doi.org10.1103/PhysRevD.108.092002https://hdl.handle.net/20.500.12713/5827Using a data sample of (1.0087 +/- 0.0044) x 10(10) J/psi events collected with the BESIII detector, the decays of J/psi -> gamma pi(0) (eta, eta ') -> gamma gamma gamma are studied. Newly measured branching fractions are B(J/psi -> gamma pi(0)) = (3.34 +/- 0.02 +/- 0.09) x 10(-5), B(J/psi -> gamma eta) = (1.096 +/- 0.001 +/- 0.019) x 10(-3), and B(J/psi -> gamma eta ') = (5.40 +/- 0.01 +/- 0.11) x 10(-3), where the first uncertainties are statistical and the second are systematic. These results are consistent with the world average values within two standard deviations. The ratio of partial widths Gamma(J/psi -> gamma eta ')/Gamma(J/psi -> gamma eta) is measured to be 4.93 +/- 0.13. The singlet-octet pseudoscalar mixing angle theta(P) is determined to be theta(P) = -(22.11 +/- 0.26)degrees or -(19.34 +/- 0.34)degrees with two different phenomenological models.eninfo:eu-repo/semantics/openAccessRadiative DecaysTofArticle1089WOS:0010968978000012-s2.0-85180970742N/A10.1103/PhysRevD.108.092002Q1