Polarization as a probe to the production mechanisms of charmonium in (pi)N collisions

摘要

Measurements of the polarization of J/(psi) produced in pion-nucleus collisions are in disagreement with leading twist QCD prediction where J/(psi) is observed to have negligible polarization whereas theory predicts substantial polarization. The authors argue that this discrepancy cannot be due to poorly known structure functions nor the relative production rates of J/(psi) and (chi)(sub j). The disagreement between theory and experiment suggests important higher twist corrections, as has earlier been surmised from the anomalous non-factorized nuclear A-dependence of the J/(psi) cross section.