Study of the polarization of upsilons at D0

We present a study of the polarization of the γ(1S) and γ(2S) using a sample of 1.3 fb-1 of data collected by the DO experiment in 2002-2006 during Run II of the Fermilab Tevatron. The polarization parameter α = (σT - 2σT)/(σT + 2σT) where σT and σL are the transverse and longitudinal polarized components of the cross section is measured as a function of transverse momentum (pT) for the γ(1S) and γ(2S). Significant longitudinal polarization that is dependent on pT is observed for the γ(1S) that is inconsistent with QCD predictions. No contradictions to the NRQCD predictions for γ(2S) are observed