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

Sirunyan A. M. , Tumasyan A., Adam W., Ambrogi F., Asilar E., Bergauer T., ...More

PHYSICS LETTERS B, vol.800, 2020 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 800
  • Publication Date: 2020
  • Doi Number: 10.1016/j.physletb.2019.135048
  • Title of Journal : PHYSICS LETTERS B
  • Keywords: CMS, Heavy ions, Electroweak, W boson, pPb, nPDF


The production of W-+/- bosons is studied in proton-lead (pPb) collisions at a nucleon-nucleon centre-of-mass energy of root s(NN) = 8.16 TeV. Measurements are performed in the W-+/- -> mu(+/-)nu(mu) channel using a data sample corresponding to an integrated luminosity of 173.4 +/- 6.1 nb(-1), 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 vertical bar eta(mu)(lab)vertical bar < 2.4 and transverse momentum p(T)(mu) > 25 GeV/c. The W-+/- boson differential cross sections, muon charge asymmetry, and the ratios of W-+/- 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. (C) 2019 The Author(s). Published by Elsevier B.V.