On Exclusive Reactions in the Time-Like Region

Abstract

The electromagnetic form factors of the proton in the time-like region and two-photon annihilations into proton-antiproton are investigated. To calculate these processes at moderately large $s$ we use a variant of the Brodsky-Lepage hard-scattering formalism where diquarks are considered as quasi-elementary constituents of baryons. The proton wave function and the parameters controlling the diquark contributions are determined from fits to space-like data. We also comment on the decay ${\eta }_c\to p\bar{p}$.

Comments: 8 pages, CERN-TH.6869/93; WU-B 93-06, latex, 3 figures as tar-compressed and uuencoded files, replaced version because the figures have been corrupted,(manfred@wpts0.physik.uni-wuppertal.de)