ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2012, vol. 86, p. -
Study of ψ(3686)→π0h c, h c→γη c via η c exclusive decays
The process ψ(3686)→π0h c, h c→γ η c has been studied with a data sample of 106±4 million ψ(3686) events collected with the BESIII detector at the BEPCII storage ring. The mass and width of the P-wave charmonium spin-singlet state h c(P11) are determined by simultaneously fitting distributions of the π0 recoil mass for 16 exclusive η c decay modes. The results, M(h c)=3525.31±0.11(stat)±0.14(syst)MeV/c2 and Γ(h c)=0.70±0.28±0.22MeV, are consistent with and more precise than previous measurements. We also determine the branching ratios for the 16 exclusive η c decay modes, five of which have not been measured previously. New measurements of the η c line-shape parameters in the E1 transition h c→γη c are made by selecting candidates in the h c signal sample and simultaneously fitting the hadronic mass spectra for the 16 η c decay channels. The resulting η c mass and width values are M(η c)=2984.49±1.16±0.52MeV/c2 and Γ(η c)=36.4±3.2±1.7MeV. © 2012 American Physical Society.