The polarizations of the Υ(1S), Υ(2S), and Υ(3S) mesons are measured in proton-proton collisions at √s=7 TeV, using a data sample of Υ(nS)→μ+μ− decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb−1. The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters λϑ, λφ, and λϑφ, as well as the frame-invariant quantity ˜λ, are presented as a function of the Υ(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges |y|<0.6 and 0.6<|y|<1.2. No evidence of large transverse or longitudinal polarizations is seen in the explored kinematic region.
Measurement of the Υ(1S), Υ(2S), and Υ(3S) Polarizations in pp Collisions at √s 7 TeV
L. Bianchini;MARTINI, LUCA;MESSINEO, ALBERTO MARIA;RIZZI, ANDREA;TONELLI, GUIDO EMILIO;A. C. Marini;
2013-01-01
Abstract
The polarizations of the Υ(1S), Υ(2S), and Υ(3S) mesons are measured in proton-proton collisions at √s=7 TeV, using a data sample of Υ(nS)→μ+μ− decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb−1. The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters λϑ, λφ, and λϑφ, as well as the frame-invariant quantity ˜λ, are presented as a function of the Υ(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges |y|<0.6 and 0.6<|y|<1.2. No evidence of large transverse or longitudinal polarizations is seen in the explored kinematic region.File | Dimensione | Formato | |
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PhysRevLett.110.081802.pdf
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