On Exclusive Reactions in the Time-Like Region

Authors:
  • PKP. Kroll
    P. Kroll
  • TPTh. Pilsner
    Th. Pilsner
  • MSM. Schuermann
    M. Schuermann
  • WSW. Schweiger
    W. Schweiger

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 $\eta_c \to p\bar{p}$.