In a previous paper [Phys. Rev. D 68, 034017 (2003)], we investigated the inclus
ive production of prompt J/psi mesons in polarized hadron-hadron, photon-hadron,
and photon-photon collisions in the factorization formalism of nonrelativistic
quantum chromodynamics providing compact analytic results for the double longitu
dinal-spin asymmetry A_{LL}. For convenience, we adopted a simplified expression
for the tensor product of the gluon polarization four-vector with its charge co
njugate, at the expense of allowing for ghost and anti-ghosts to appear as exter
nal particles. While such ghost contributions cancel in the cross section asymme
try A_{LL} and thus were not listed in our previous paper, they do contribute to
the absolute cross sections. For completeness and the reader's convenience, the
y are provided in this addendum.
