Photon-gluon-fusion analysis of charm photoproduction

Results on the photoproduction of 10 000 fully reconstructed charmed particles from the ${10}^8$ 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 ${\mathit{p}}_{\mathit{T}}^2$ and ${\mathit{x}}_{\mathit{F}}$ distributions can be explained by a high mass for the charm quark (${\mathit{m}}_{\mathit{c}}$=1.${74}_{\mathrm{-}0.18}^{+0.13\mathrm{}}$ GeV/${\mathit{c}}^2$) and a soft-gluon distribution [G(x)∼(1-x${)}_{\mathit{g}}^{\mathit{n}}$, where ${\mathit{n}}_{\mathit{g}}$=7.1±2.2].