J/psi production in association with a charm-quark pair at the Tevatron

I study the direct hadroproduction of J\psi associated with a charm-quark pair at leading order in alpha_S and v in NRQCD. This process provides an interesting signature that could be studied at the Tevatron. I consider both colour-singlet and colour-octet transitions. I compare our results to the fragmentation approximation and discuss the associated experimental signatures.