Measurement of Polarization of the Υ ( 1 S ) and Υ ( 2 S )

We present a study of the polarization of the Υ(1S) and Υ(2S) using a sample of 1.3 fb −1 of data collected by the D0 experiment in 20022006 during Run II of the Fermilab Tevatron. The polarization parameter α = (σ T − 2σ T)/(σ T + 2σ T) where σ T and σ L are the transverse and longitudinal polarized components of the cross section is measured as a function of transverse momentum (p T) for the Υ(1S) and Υ(2S). Signicant longitudinal polarization that is dependent on p T is observed for the Υ(1S) that is inconsistent with QCD predictions. No contradictions to the NRQCD predictions for Υ(2S) are observed.