Measurement of ψ(2S) polarisation in pp collisions at √s = 7 TeV

The polarisation of prompt ψ(2S) mesons is measured by performing an angular analysis of ψ(2S) → μ[superscript +]μ[superscript −] decays using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb[superscript −1], collected by the LHCb detector at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse momentum p[subscript T] and rapidity y in the kinematic region 3.5 < p[subscript T] < 15 GeV/c and \(2.0 , and is compared to theoretical models. No significant polarisation is observed.National Science Foundation (U.S.