Hard exclusive baryon-antibaryon production in two-photon collisions

Abstract.

We study baryon pair production in two-photon collisions, $\gamma \gamma \rightarrow B \bar{B}$, within perturbative quantum chromodynamics, treating baryons as quark-diquark systems. We extend previous work within the same approach by treating constituent-mass effects systematically by means of an expansion in the small parameter (mass/photon energy). Our approach enables us to give a consistent description of the cross sections for all octet baryon channels. Adopting the model parameters from foregoing work, we are able to reproduce the most recent large-momentum-transfer data from LEP for the $p\bar{p}$, $\Lambda\bar{\Lambda}$, and $\Sigma^0\bar{\Sigma}^0$ channels in a quite satisfactory way. We also briefly address the crossed process for the proton channel, $\gamma p \rightarrow \gamma p$.