Predictions for the eta_c-gamma transition form factor

Abstract

The eta_c-gamma transition form factor is calculated in a model based on a modified hard scattering approach to exclusive reactions, in which transverse degrees of freedom are taken into account. For the eta_c-meson a distribution amplitude of the Bauer-Stech-Wirbel type is used, where the two free parameters, namely the decay constant f(eta_c) and the transverse size of the wave function, are related to the Fock state probability and the width for the two-photon decay Gamma[eta_c -> gamma gamma].

5 pages, LaTeX (sprocl.sty, h-physrev.bst, 2 ps-figures incl.), Talk presented at Photon'97, Egmond (NL), May 97 (to appear in the proceedings, see also http://www.nikhef.nl/pub/conferences/photon97/), postscript file available at http://wptu38.physik.uni-wuppertal.de/~feldmann/pub/9706224.ps.gz (Ref. [1] completed)