APS » PROLA » Phys. Rev. Lett. » Volume 86 » Issue 12

Phys. Rev. Lett. 86, 2529 - 2532 (2001)

Observation of Polarization in Bottomonium Production at √s  =  38.8 GeV

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C. N. Brown et al. (FNAL E866/NuSea Collaboration)
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Received 7 November 2000

We present a measurement of the polarization observed for bottomonium states produced in p-Cu collisions at sqrt[s]  =  38.8  GeV. 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>1.8  GeV/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.


©2001 The American Physical Society

URL: http://link.aps.org/abstract/PRL/v86/p2529
DOI: 10.1103/PhysRevLett.86.2529
PACS: 13.88.+e, 14.40.Nd

* Present address: University of Illinois at Urbana–Champaign, Urbana, IL 61801.
† Present address: Florida State University, Tallahassee, FL 32306.
‡ Present address: University of Illinois at Urbana–Champaign, Urbana, IL 61801.
§ On leave from Kurchatov Institute, Moscow, 123182 Russia.

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