Search for ηc (2S) →p p ¯ K+K- and measurement of χcJ →p p ¯ K+K- in ψ (3686) radiative decays

A search for ηc(2S)→pp¯K+K-, together with measurement of branching fractions of χcJ(J=0,1,2)→pp¯K+K- in the ψ(3686)→γηc(2S) and the ψ(3686)→γχcJ radiative decays, is performed with (2712.4±14.3)×106 ψ(3686) events collected with the BESIII detector at the BEPCII collider. An evidence for ηc(2S)→pp¯K+K- is found, with a significance of 3.3σ. The product branching fraction of B[ψ(3686)→γηc(2S)]·B[ηc(2S)→pp¯K+K-] is determined to be (1.98±0.41stat±0.99syst)×10-7. The product branching fractions of B[ψ(3686)→γχcJ]·B[χcJ→pp¯K+K-] are measured to be (2.49±0.03stat±0.15syst)×10-5, (1.83±0.02stat±0.11syst)×10-5, and (2.43±0.02stat±0.15syst)×10-5, for J=0, 1, and 2, respectively.