Prompt psi(2S) polarization in pp collisions at 7 TeV

The polarization of prompt $\psi$(2S) mesons is measured in proton-proton collisions at $\sqrt{s} = 7\,$TeV, using a data sample of $\psi\mathrm{(2S)} \rightarrow \mu^+\mu^-$ decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9$\,$fb$^{-1}$. The dimuon decay angular distributions are analysed in three different polarization frames. The prompt $\psi$(2S) polarization parameters $\lambda_\vartheta$, $\lambda_\varphi$, and $\lambda_{\vartheta\varphi}$, as well as the frame-invariant $\tilde{\lambda}$, are measured as a function of the $\psi$(2S) transverse momentum, $p_{\rm T}$, between 14 and 50$\,$GeV, in the rapidity ranges $|y|<0.6$ and $0.6<|y|<1.2$. No evidence of large transverse or longitudinal polarizations is seen in the explored kinematic region.