  We compute the helicity density matrix of $\rho$ vector mesons produced in
the two-body decays of polarized $\chi_{c2}$'s in the framework of massless
perturbative QCD. The $\chi_{c2}$'s are either exclusively or inclusively
produced in $p \, \bar p$ or $p \, p$ interactions, via quark-antiquark
annihilation or gluon fusion. Our results show unambiguous significant
differences depending on the choice of the $\rho$ distribution amplitudes and
allow to discriminate between different proposed models.
