Ghost contributions to charmonium production in polarized high-energy collisions

TL;DR

This paper discusses ghost contributions to charmonium production in polarized high-energy collisions, clarifying their role in absolute cross sections within the nonrelativistic QCD framework.

Contribution

It provides a detailed analysis of ghost contributions to absolute cross sections, complementing previous work on spin asymmetries in charmonium production.

Findings

Ghost contributions cancel in spin asymmetry calculations.

Ghosts contribute to the absolute cross sections.

Provides explicit formulas for ghost contributions.

Abstract

In a previous paper [Phys. Rev. D 68, 034017 (2003)], we investigated the inclusive 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 longitudinal-spin asymmetry A_{LL}. For convenience, we adopted a simplified expression for the tensor product of the gluon polarization four-vector with its charge conjugate, at the expense of allowing for ghost and anti-ghosts to appear as external particles. While such ghost contributions cancel in the cross section asymmetry 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, they are provided in this addendum.