Mechanism ofJψproduction: Determining gluon distributions

Assuming a generalized Drell-Yan-type mechanism for hadronic $\psi$ production, the relative importance of the different possible contributions is estimated from the data. We find that about 80% of the $\mathrm{pp}\to \psi X$ cross section is due to gluons. Therefore, these data give some information on the gluon distribution $G\left(x\right)\mathrm{}$ in the proton. Assuming $\mathrm{xG}\left(x\right)\mathrm{}\propto {\mathrm{}(1-x)\mathrm{}}^n$, data restrict $n$ to the range 4-6, in agreement with dimensional-counting rules. The energy dependence of $\frac{\sigma (\overline{p}p\to \psi X)}{\sigma (pp\to \psi X)}$ is predicted.