Probing the polarized gluon content of the proton through chi₂ hadroproduction

Determining how much spin is carried by gluon in a polarized proton is a fundamental problem which cannot be resolved by completely inclusive deep inelastic measurements. Hadroproduction of heavy flavors is very sensitive to the gluon content of hadrons. We show that $\chi_2 (3555)$ production in polarized proton-proton collisions is a good candidate reaction to address this challenging question.