Abstract:
Differential cross sections for the Drell-Yan process, including Z boson production,
using the dimuon decay channel are measured in proton-lead (pPb) collisions at a
nucleon-nucleon centre-of-mass energy of 8.16TeV. A data sample recorded with the CMS
detector at the LHC is used, corresponding to an integrated luminosity of 173 nb−1. The
differential cross section as a function of the dimuon mass is measured in the range 15–
600 GeV, for the first time in proton-nucleus collisions. It is also reported as a function
of dimuon rapidity over the mass ranges 15–60 GeV and 60–120 GeV, and ratios for the
p-going over the Pb-going beam directions are built. In both mass ranges, the differential
cross sections as functions of the dimuon transverse momentum pT and of a geometric variable
are measured, where highly correlates with pT but is determined with higher
precision. In the Z mass region, the rapidity dependence of the data indicate a modification
of the distribution of partons within a lead nucleus as compared to the proton case. The
data are more precise than predictions based upon current models of parton distributions.
