Reassessing the importance of the colour-singlet contributions to direct J/psi+W production at the LHC and the Tevatron

Understand

We show that the colour-singlet contributions to the hadroproduction of J/psi in association with a W boson are sizable, if not dominant over the colour-octet contributions.

• They are of two kinds, sg -> J/psi + c + W at alpha^3_S alpha and q q'-bar -> gamma*/Z* W -> J/psi W at order alpha^3.
• These have not been considered in the literature until now.
• Our conclusion is that the hadroproduction of a J/psi in association with a W boson cannot be claimed as a clean probe of the colour-octet mechanism.