Measurement of the polarization of the upsilon(1S) and upsilon(2S) states in pp collisions at square root[s]=1.96 TeV

Phys Rev Lett. 2008 Oct 31;101(18):182004. doi: 10.1103/PhysRevLett.101.182004. Epub 2008 Oct 31.

Abstract

We present a study of the polarization of the Upsilon(1S) and Upsilon(2S) states using a 1.3 fb;{-1} data sample collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron Collider. We measure the polarization parameter alpha=(sigma_{T}-2sigma_{L})/(sigma_{T}+2sigma_{L}), where sigma_{T} and sigma_{L} are the transversely and longitudinally polarized components of the production cross section, as a function of the transverse momentum (p_{T};{Upsilon}) for the Upsilon(1S) and Upsilon(2S). Significant p_{T};{Upsilon}-dependent longitudinal polarization is observed for the Upsilon(1S). A comparison with theoretical models is presented.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.