Measurement of J/ψ polarization in pp collisions at √s =7 TeV

CERN-LHC. An angular analysis of the decay J/ψ→μ+μ− is performed to measure the polarization of prompt J/ψ mesons produced in pp collisions at √s=7 TeV. The dataset corresponds to an integrated luminosity of 0.37 fb-1 collected with the LHCb detector. The measurement is presented as a function of transverse momentum, pT, and rapidity, y, of the J/ψ meson, in the kinematic region 2 <pT<15 GeV/c and 2.0 <y< 4.5.