Measurement of the Drell-Yan forward-backward asymmetry at high dilepton masses in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A measurement of the forward-backward asymmetry of pairs of oppositely
charged leptons (dimuons and dielectrons) produced by the Drell-Yan process in protonproton collisions is presented. The data sample corresponds to an integrated luminosity of
138 fb−1
collected with the CMS detector at the LHC at a center-of-mass energy of 13 TeV.
The asymmetry is measured as a function of lepton pair mass for masses larger than 170 GeV
and compared with standard model predictions. An inclusive measurement across both
channels and the full mass range yields an asymmetry of 0.612±0.005 (stat)±0.007 (syst).
As a test of lepton flavor universality, the difference between the dimuon and dielectron
asymmetries is measured as well. No statistically significant deviations from standard
model predictions are observed. The measurements are used to set limits on the presence
of additional gauge bosons. For a Z
0
boson in the sequential standard model the observed
(expected) 95% confidence level lower limit on the Z
0 mass is 4.4 TeV (3.7 TeV).