ϒ(nS) polarizations in pp collisions at $\sqrt{s}=7$ and 8 TeV by the LHCb collaboration

A polarization measurement carried out for the ϒ(1S), ϒ(2S) and ϒ(3S) mesons produced in pp collisions at $\sqrt{s}=7$ and 8 TeV is presented. Data samples used for the polarization measurement were collected by the LHCb experiment during the 2011 and 2012 data taking runs with integrated luminosities of 1 and 2fb⁻¹, respectively. The measurement has been performed in three polarization frames, using an angular distribution analysis of the ϒ → μ⁺ μ⁻ decays in the kinematic region of the ϒ transverse momentum $p_T^{{\rm Y}}<30GeV/c$ and rapidity 2.2 < y ^ϒ < 4.5. No large polarization is observed. (paper)