Production of<i>J</i>/ψ at large<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="italic">x</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="italic">F</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>in 800 GeV/<i>c</i><i>p</i>-copper and<i>p</i>-beryllium collisions

The differential cross sections d\ensuremath{\sigma}/${\mathit{dx}}_{\mathit{F}}$ for J/\ensuremath{\psi} produced inclusively in 800 GeV/c p-Cu and p-Be collisions have been measured in the kinematic range 0.30\ensuremath{\le}${\mathit{x}}_{\mathit{F}}$\ensuremath{\le}0.95 through the decay mode J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$. 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/\ensuremath{\psi} production in heavy nuclei at large ${\mathit{x}}_{\mathit{F}}$.