Transverse correlation of charm pairs, ψψ and partons transverse momenta

Assuming the partons within the initial hadrons to have transverse momentum we have calculated in the framework of the fusion process the transverse angular distributions of the charm pairs and of the ψψ pairs produced in hadronic collisions. The transverse angle is defined as cosφ = P1'3× P1'4/(|P1'3||P1'4|) where p T3 and p T4 are the transverse momenta of the charm pairs/ ψψ pairs. By comparing with the data we find that the effective transverse momentum of the partons is ~0.6 GeV/c