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

CERN-LHC. The polarisation of prompt PSI(2S) mesons is measured by performing an angular analysis of PSI(2S) --> MU+ MU- decays using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb^{-1}, collected by the LHCb detector in 2011 at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse momentum, PT, and rapidity, YRAP, in the kinematic region 3.5 < PT < 15 GeV and 2.0 < YRAP < 4.5.