Measurement of the prompt $J/\\psi$ and $\\psi$(2S) polarizations in $pp$ collisions at $\\sqrt{s}$ = 7 TeV
Journal
Physics Letters
Journal Volume
B727
Pages
381-402
Date Issued
2013-07
Author(s)
Abstract
The polarizations of prompt J / and (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 fb -1 . The prompt J / and (2S) polarization parameters , , and , as well as the frame-invariant quantity , are measured from the dimuon decay angular distributions in three different polarization frames. The J / results are obtained in the transverse momentum range 14 < p T < 70 GeV, in the rapidity intervals |y| < 0.6 and 0.6 < |y| < 1.2. The corresponding (2S) results cover 14 < p T < 50 GeV and include a third rapidity bin, 1.2 < |y| < 1.5. No evidence of large polarizations is seen in these kinematic regions, which extend much beyond those previously explored.
Type
journal article