Observation of χcJ(J=0,1,2)→ pp̄η η

A bstract Using (2712 . 4 ± 14 . 3) × 10 6 ψ (3686) candidates collected by the BESIII detector operating at the BEPCII storage ring, the decays χcJ(J=0,1,2)→ pp̄η η χ cJ J = 0 1 2 → p p ¯ ηη are observed for the first time through the radiative transition ψ (3686) → γχ cJ . The statistical significances for χ cJ signals are all larger than 5 σ . The branching fractions of χc0,1,2→ pp̄η η χ c 0 , 1 , 2 → p p ¯ ηη are determined to be (5 . 75 ± 0 . 59 ± 0 . 42) × 10 − 5 , (1 . 40 ± 0 . 33 ± 0 . 17) × 10 − 5 , and (2 . 64 ± 0 . 40 ± 0 . 27) × 10 − 5 , respectively, where the first uncertainties are statistical and the second systematic. No evident resonant structures are found in the pp̄ p p ¯ and pη /p̄η pη / p ¯ η systems.