Flavor symmetry breaking and mixing effects
in the and transition form factors
T. Feldmann - P. Kroll
Department of Theoretical Physics, University of Wuppertal,
D-42097 Wuppertal, Germany
Received: 13 November 1997 / Revised version: 13 January 1998 / Published online: 10 March 1998
We reanalyze the and transition form factors within the modified hard scattering approach on the basis of new experimental data from CLEO [CLEO97] and L3 [L397]. Our approach perfectly describes the experimental data over a wide range of the virtuality of the probing photon, 1 GeV GeV2. The analysis provides hints that the conventional flavor octet-singlet scheme for the -mixing is too simple. A more general mixing scheme on the other hand, involving two mixing angles, leads to a very good description of the transition form factors and also accounts for the two-photon decay widths of the and mesons as well as for the ratio of the widths for the and decays. We also investigate the questions of possible deviations of the and distribution amplitudes from the asymptotic form and of eventual intrinsic charm in the and mesons. We estimate the charm decay constant of the meson to lie within the range -65 MeV MeV.