Measurement of the Y(nS) polarizations in pp collisions at s = 7 $$ \sqrt{s}=7 $$ and 8 TeV

The polarization of the (1S), (2S) and (3S) mesons, produced in pp collisions at centre-of-mass energies s = 7 and 8 TeV, is measured using data samples collected by the LHCb experiment, corresponding to integrated luminosities of 1 and 2 fb -1 , respectively. The measurements are performed in three polarization frames, using decays in the kinematic region of the transverse momentum p T < 30 GeV/c and rapidity 2.2 < y < 4.5. No large polarization is observed.