Polarization as a Probe to the Production Mechanisms of Charmonium in $\pi N$ Collisions

Abstract

Measurements of the polarization of $\text{jp}$ produced in pion-nucleus collisions are in disagreement with leading twist QCD prediction where $\text{jp}$ is observed to have negligible polarization whereas theory predicts substantial polarization. We argue that this discrepancy cannot be due to poorly known structure functions nor the relative production rates of $\text{jp}$ and ${\chi }_J$. 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 $\text{jp}$ cross section.

Comments: 8 pages