Measurement of the prompt J/psi and psi(2S) polarizations in pp collisions at sqrt(s)=7 TeVстатья
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Дата последнего поиска статьи во внешних источниках: 4 февраля 2014 г.
Аннотация:The polarizations of prompt J/ψ and ψ(2S) mesons are measured in proton-proton collisions at s√ = 7 TeV, using a dimuon data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The prompt J/ψ and ψ(2S) polarization parameters λθ,λϕ, and λθ,ϕ, as well as the frame-invariant quantity λ˜, are measured from the dimuon decay angular distributions in three different polarization frames. The J/ψ results are obtained in the transverse momentum range 14 <pT< 70 GeV, in the rapidity intervals abs(y) <0.6 and 0.6<abs(y)<1.2. The corresponding ψ(2S) results cover 14 <pT< 50 GeV and include a third rapidity bin, 1.2 <abs(y)< 1.5. No evidence of large transverse or longitudinal polarizations is seen in these kinematic regions, which extend much beyond those previously explored.