Photoproduction Cross Sections of Baryon—Antibaryon Pairs at GlueX.

The reaction mechanisms contributing to baryon—antibaryon photoproduction have not been clearly delineated in the past, in part because almost no data existed before now. At GlueX, total cross-sections and differential cross-sections of the reactions γp→BB̅p (where BB̅ includes p-p̅ and Λ-Λ̅) have been obtained from the reaction thresholds up to a beam photon energy of 11.4 GeV. The data encompass 30 million events from the GlueX Phase-I period (2017 - 2018). Phenomenological Monte Carlo models with physical interpretations have been developed to understand various aspects observed in the data, including the angular distributions of the final state particles and various invariant mass distributions of particle pairs. These include single-Regge mechanisms modeled by a single well-defined t-channel slope and a clustering parameter for the created baryon pairs. In addition, the data strongly suggest double-Regge mechanisms that involve different slopes. Preliminary cross sections results will be presented, including similarities and the differences seen when creating neutral versus charged or strange versus non-strange baryons using photoproduction.