  We firstly re-examine hadroproduction of prompt J/psi's at the Fermilab
Tevatron finding that those colour-octet matrix elements presented in
literature are systematically overestimated due to the overlooking of the
effective primordial transverse momentum of partons (i.e. dynamically generated
via initial-state radiation). We estimate the size of these effects using
different parton distribution functions in a Monte Carlo framework. Finally, we
extrapolate up to LHC energies making a prediction on the expected pt
differential cross-section for charmonium.
