Testing J/ψ production and decay properties in hadronic collisions

The polar and azimuthal angular distributions for the lepton pair arising from the decay of a J/ψ meson produced at transverse momentum pT balanced by a photon (or gluon) in hadronic collisions are calculated in the color singlet model (CSM). It is shown that the general structure of the decay lepton distribution is controlled by four invariant structure functions, which are functions of the transverse momentum and the rapidity of the J/ψ. We find that two of these structure functions (the longitudinal and transverse interference structure functions) are identical in the CSM. Analytical and numerical results are given in the Collins-Soper and in the Gottfried-Jackson frames. We present a Monte Carlo study of the effect of acceptance cuts applied to the leptons and the photon for J/ψ+γ production at the Fermilab Tevatron.