Measurement of the branching fraction of the decay J/ψ →p p ̄ η

A high-precision measurement of the branching fraction of the decay J/ψ→pp¯η is performed using (10 087±44)×106 J/ψ events recorded by the BESIII detector at the BEPCII storage ring. The branching fractions of the two decays J/ψ→pp¯η(η→γγ) and J/ψ→pp¯η(η→π+π-π0) are measured individually to be B(J/ψ→pp¯η(η→γγ))=(1.480±0.001±0.024)×10-3 and B(J/ψ→pp¯η(η→π+π-π0))=(1.557±0.003±0.038)×10-3, where the first uncertainties are statistical and the second systematic. Both results are compatible within their uncorrelated systematic uncertainties. The combined result is B(J/ψ→pp¯η)=(1.495±0.001±0.023)×10-3, where the first uncertainty is the combined statistical uncertainty and the second one the combined systematic uncertainty of both analyses, incorporating correlations between them. In addition, the pp¯ threshold region is investigated for a potential threshold enhancement, and no evidence for one is observed.