Observation of Polarization in Bottomonium Production at s=38.8 GeV

Phys. Rev. Lett. 86, 2529 – Published 19 March 2001
C. N. Brown et al. (FNAL E866/NuSea Collaboration)


We present a measurement of the polarization observed for bottomonium states produced in p-Cu collisions at s=38.8GeV. The angular distribution of the decay dimuons of the ϒ(1S) state shows no polarization at small values of the fractional longitudinal momentum xF and transverse momentum pT but significant positive transverse production polarization for either pT>1.8GeV/c or for xF>0.35. The ϒ(2S+3S) (unresolved) states show a large transverse production polarization at all values of xF and pT measured. These observations challenge NRQCD calculations of the polarization expected in the hadronic production of bottomonium states.

DOI: http://dx.doi.org/10.1103/PhysRevLett.86.2529

  • Received 7 November 2000
  • Published in the issue dated 19 March 2001

© 2001 The American Physical Society

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