Fig. 9.

Measured cross section ratio $R_{\text{c}}^{\pm }$ as a function of the absolute value of ${\eta }^{\ell }$ (upper) and $p_{\text{T}}^{\ell }$ (lower), compared with the NLO QCD $\mathrm{M}\mathrm{C}\mathrm{F}\mathrm{M}$ calculations using different NLO PDF sets. Error bars on data points include statistical and systematic uncertainties. Symbols showing the theoretical expectations are slightly displaced in the horizontal axis for better visibility. The ratios of data to predictions are shown in the lower panels. The uncertainty in the ratio includes the uncertainties in both data and prediction