Measurement of $\psi(2S)$ production in proton-lead and proton-proton collisions at $\sqrt{s_{NN}} = 5.02~\mathrm{TeV}$

This note reports the measurement of prompt $\psi$(2S) production in proton-lead (pPb) and proton-proton (pp) collisions at $\sqrt{s_{NN}} = 5.02~\mathrm{TeV}$. The results are based on pPb and pp data samples collected by CMS at the LHC corresponding to an integrated luminosity of 34.6 nb$^{-1}$ and 28.0 pb$^{-1}$ respectively. The nuclear modification factor, $R_{\rm pPb}$, is calculated for prompt $\psi$(2S) in the kinematic interval $4 < p_{T} < 30~\mathrm{GeV}/c$ and $-2.4 < y_{\rm CM} < 1.93$, and compared to the $R_{\rm pPb}$ of prompt $J/\psi$. The $R_{\rm pPb}$ of the excited state is found to be smaller than the $R_{\rm pPb}$ of the ground state, over the whole kinematic range studied. The suppression is more pronounced in the region of negative rapidity and $p_{T} < 10~\mathrm{GeV}/c$.