Upper bound on charmed quarks in nucleons from the cross section forψ(3100)photoproduction

A Drell-Yan-type calculation of $\psi \mathrm{}\left(3100\right)\mathrm{}$ photoproduction based on the recent data from SPEAR gives a surprisingly large cross section. If the results of the photoproduction experiment at Fermilab are similar to naive vector-meson-dominance expectations, a stringent upper bound on charmed quarks in nucleons is obtained. A consequence for $\nu W_2$ at high $\omega$ is also noted.