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Observation of polarization in bottomonium production at s**(1/2) = 38.8-GeV

The NuSea collaboration Brown, C.N. ; Awes, T.C. ; Beddo, M.E. ; et al.
Phys.Rev.Lett. 86 (2001) 2529-2532, 2001.
Inspire Record 536629 DOI 10.17182/hepdata.19423

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 Upsilon(1S) state show no polarization at small xF and pT but significant positive transverse production polarization for either pT > 1.8 GeV/c or for xF > 0.35. The Upsilon(2S+3S) unresolved states show a large transverse production polarization at all values of xF and pT measured. These observations are compared with an NRQCD calculation that predicts a transverse polarization in bottomonium production arising from quark-antiquark fusion and gluon-gluon fusion diagrams.

6 data tables
Table 1

The observed polarization in the Drell-Yan sideband region as a function of PT. There is an additional systematic uncertainty of 0.02 in the polarization measurements.

Table 2

The observed polarization in the Drell-Yan sideband region as a function of XL. There is an additional systematic uncertainty of 0.02 in the polarization measurements.

Table 3

The observed polarization in the UPSILON(1S) region as a function of PT. There is an additional systematic error of 0.06 in the polarization measurements.

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