Production ofJ/ψ at largexFin 800 GeV/cp-copper andp-beryllium collisions

The differential cross sections dσ/${\mathit{dx}}_{\mathit{F}}$ for J/ψ produced inclusively in 800 GeV/c p-Cu and p-Be collisions have been measured in the kinematic range 0.30≤${\mathit{x}}_{\mathit{F}}$≤0.95 through the decay mode J/ψ→${\mathrm{\mu }}^{+}$ ${\mathrm{\mu }}^{\mathrm{-}}$. They are compared with the predictions of the semilocal duality model for several sets of parton density functions. No evidence for a suggested intrinsic charm contribution to the cross section is observed. The ratio of the differential cross sections for Cu and Be targets confirms the suppression of J/ψ production in heavy nuclei at large ${\mathit{x}}_{\mathit{F}}$.