2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 26, 567-577 (2003)
DOI: 10.1140/epjc/s2002-01075-4

Two-photon annihilation into baryon-antibaryon pairs

M. Diehl1, P. Kroll2 and C. Vogt3

1  Institut für Theoretische Physik E, RWTH Aachen, 52056 Aachen, Germany
2  Fachbereich Physik, Universität Wuppertal, 42097 Wuppertal, Germany
3  Nordita, Blegdamsvej 17, 2100 Copenhagen, Denmark


(Received: 3 July 2002 / Revised version: 7 October 2002 / Published online: 20 November 2002 )

Abstract
We study the handbag contribution to two-photon annihilation into baryon-antibaryon pairs at large energy and momentum transfer. We derive factorization of the process amplitude into a hard $\gamma\gamma \to q\overline{q}$ subprocess and form factors describing the soft $q\overline{q}\to B\overline{B}$ transition, assuming that the process is dominated by configurations where the (anti)quark approximately carries the full momentum of the (anti)baryon. The form factors represent moments of time-like generalized parton distributions, so-called $B\overline{B}$ distribution amplitudes. A characteristic feature of the handbag mechanism is the absence of isospin-two components in the final state, which in combination with flavor symmetry provides relations among the form factors for the members of the lowest-lying baryon octet. Assuming dominance of the handbag contribution, we can describe current experimental data with form factors of plausible size, and predict the cross sections of presently unmeasured $B\overline{B}$ channels.



© Società Italiana di Fisica, Springer-Verlag 2003