Observation of nuclear modifications in W-+/- boson production in pPb collisions at root s(NN)=8.16 TeV

Abstract

The production of bosons is studied in proton-lead (pPb) collisions at a nucleon-nucleon centre-of-mass energy of . Measurements are performed in the channel using a data sample corresponding to an integrated luminosity of , collected by the CMS Collaboration at the LHC. The number of positively and negatively charged W bosons is determined separately in the muon pseudorapidity region in the laboratory frame and transverse momentum . The boson differential cross sections, muon charge asymmetry, and the ratios of boson yields for the proton-going over the Pb-going beam directions are reported as a function of the muon pseudorapidity in the nucleon-nucleon centre-of-mass frame. The measurements are compared to the predictions from theoretical calculations based on parton distribution functions (PDFs) at next-to-leading-order. The results favour PDF calculations that include nuclear modifications and provide constraints on the nuclear PDF global fits.