The hc(1P1) state of charmonium has been observed in the reaction ψ(2S)→π0hc→(γγ)(γηc) using 3.08×106 ψ(2S) decays recorded in the CLEO detector. Data have been analyzed both for the inclusive reaction, where the decay products of the ηc are not identified, and for exclusive reactions, in which ηc decays are reconstructed in seven hadronic decay channels. We find M(hc)=3524.4±0. 6±0.4MeV which corresponds to a hyperfine splitting ΔMhf(1P) M(3PJ)-M(1P1)=+1.0±0.6±0.4MeV, and B(ψ(2S)→π0hc) ×B(hc→γηc)=(4.0±0.8±0.7)×10-4.
ASJC Scopus subject areas
- Physics and Astronomy(all)