Photon - gluon fusion analysis of charm photoproduction.

Results on the photoproduction of 10 000 fully reconstructed charmed particles from the 10{sup 8} recorded triggers of Fermilab experiment E691 have been analyzed in the photon-gluon-fusion model. We find that the total cross section, its rise with energy, and the {ital p}{sub {ital T}}{sup 2} and {ital x}{sub {ital F}} distributions can be explained by a high mass for the charm quark ({ital m}{sub {ital c}}=1.74{sub {minus}0.18}{sup +0.13} GeV/{ital c}{sup 2}) and a soft-gluon distribution ({ital G}({ital x}){approximately}(1{minus}{ital x}){sup {ital n}{sub {ital g}}}, where {ital n}{sub {ital g}}=7.1{plus minus}2.2).