Observation of χcJJ=012→pp ̄ηη

Using (2712.4 ± 14.3) × 10⁶ψ(3686) candidates collected by the BESIII detector operating at the BEPCII storage ring, the decays χcJJ=012→pp¯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 5σ. The branching fractions of χc0,1,2→pp¯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 pp¯ and pη/p¯η systems.