DOI: 10.1140/epjc/s2002-01075-4
Two-photon annihilation into baryon-antibaryon pairs
M. Diehl1, P. Kroll2 and C. Vogt31 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
subprocess and form factors describing
the
soft
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
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
channels.
© Società Italiana di Fisica, Springer-Verlag 2003