Search for new hadronic decays of h c and observation of h c → $p\overline{p}\eta $

A search for the hadronic decays of the h c meson to the final states $p\overline{p}$ π + π − π 0, $p\overline{p}\eta $ , and $p\overline{p}$ π 0 via the process ψ(3686) → π 0 h c is performed using (4.48 ± 0.03) × 108 ψ(3686) events collected with the BESIII detector. The decay channel h c → $p\overline{p}\eta $ is observed for the first time with a significance greater than 5σ and a branching fraction of (6.41 ± 1.74 ± 0.53 ± 1.00) × 10 −4, where the uncertainties are statistical, systematic, and that from the branching fraction of ψ(3686) → π 0 h c . Strong evidence for the decay h c → $p\overline{p}$ π + π − π 0 is found with a significance of 4.9σ and a branching fraction of (3.84 ± 0.83 ± 0.69 ± 0.58) × 10 −3. The significances include systematic uncertainties. No clear signal of the decay h c → $p\overline{p}$ π 0 is found, and an upper limit of 6.59 × 10 −4 on its branching fraction is set at the 90% confidence level.