Measurement of the branching fraction of the decay J/ p p

A high precision measurement of the branching fraction of the decay J/ p p is performed using (10 087 44) 10⁶ J/ events recorded by the BESIII detector at the BEPCII storage ring. The branching fractions of the two decays J/ p p () and J/ p p (^+ ^- ⁰) are measured individually to be B (J/ p p () ) = (1. 480 0. 001 0. 024) \, 10^-3 and B (J/ p p (^+ ^- ⁰) ) = (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/ p p) = (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 p p threshold region is investigated for a potential threshold enhancement, and no evidence for one is observed.