First Evidence for eta_c(2S) Decays to p pbar K+ K-
A BESIII measurement using (2712.4 +/- 14.3) million psi(3686) events that finds the first evidence (3.3 sigma) for eta_c(2S) -> p pbar K+ K- in the radiative transition psi(3686) -> gamma eta_c(2S), measuring B[psi(3686) -> gamma eta_c(2S) -> gamma p pbar K+ K-] = (1.98 +/- 0.41 +/- 0.99) x 10^-7 (90% C.L. upper limit 4.1 x 10^-7), and reporting the first product branching fractions of psi(3686) -> gamma chi_cJ -> gamma p pbar K+ K- for chi_c0, chi_c1, chi_c2 with improved precision. Motivated by the poorly understood decay dynamics of pseudoscalar charmonia and the inconsistent predictions for the ratio Q_P of eta_c(2S) to eta_c hadronic branching fractions.
Search for ηc(2S) →p¯pK+K−and measurement of χcJ →p¯pK+K−in ψ(3686) radiative decays M. Ablikim1
Using (2712.4 +/- 14.3) x 10^6 psi(3686) events collected with the BESIII detector at BEPCII, the paper searches for the decay eta_c(2S) -> p pbar K+ K- in the radiative transition psi(3686) -> gamma…