Observation of Xc and Xb nuclear suppression via dilepton polarization measurements

We demonstrate that it is possible to use the polarization of vector quarkonia, measured from dilepton event samples, as an instrument to study the suppression of chi(c) and chi(b) in heavy-ion collisions, where a direct determination of signal yields involving the identification of low-energy photons is essentially impossible. A change of the observed J/ psi and Y(1S) polarizations from proton-proton to central nucleus-nucleus collisions would directly reflect differences in the nuclear dissociation patterns of S and P states and may provide a strong indication for quarkonium sequential suppression in the quark-gluon plasma.