Constraints on nuclear parton distributions from W boson production in pPb collisions at $\sqrt{s_{\mathrm{NN}}} = 8.16~\mathrm{TeV}$

The production of W bosons has been measured in proton-lead collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\mathrm{NN}}} = 8.16~\mathrm{TeV}$. The measurement of W bosons is performed in the $\mathrm{W}\rightarrow\mu\nu_{\mu}$ channel, using a data sample with integrated luminosity of $173.4 \pm 8.7~\mathrm{nb}^{-1}$ collected by the CMS experiment at the CERN LHC. The number of positive and negative W bosons is determined in the muon pseudorapidity region $|\eta_{\mathrm{lab}}|<2.4$ and transverse momentum $p_{\mathrm{T}}^{\mu}>25$ GeV/$c$. The W boson differential cross sections, muon charge asymmetry, and the ratios of W boson yields on the p-going over the Pb-going directions are reported as a function of the muon pseudorapidity in the center-of-mass frame. The measurements are compared to the predictions from theoretical calculations based on parton distribution functions (PDF). The results of this analysis favor PDF calculations including nuclear modifications and provide constraints on the nuclear PDF global fits.