Charmonia production in hadron colliders and the extraction of colour-octet matrix elements
We present the results of our analysis on charmonia ($J/ψ$ and $ψ'$) hadroproduction taking into account higher-order QCD effects induced by initial-state radiation in a Monte Carlo framework, with the colour-octet mechanism implemented in the event generation. We find that those colour-octet matrix elements extracted so far from Fermilab Tevatron data for both $J/ψ$ and $ψ'$ production have to be lowered significantly. We finally make predictions for charmonia production at the LHC, presenting a code for a fast simulation with PYTHIA based on the colour-octet model.