Ratio of the W$^+$ to W$^-$ production cross section as a function of $p_{\textrm{T}}$ at midrapidity in pp collisions at $\sqrt{s}=$ 13 TeV. The symbols are placed at the centre of the $p_{\rm T}$ interval. The statistical uncertainties are represented by vertical bars The curves with different colours are POWHEG calculations with the CT14NNLO , CT18NLO  and NNPDF4.0  PDF sets. Uncertainties on the calculations are assumed to cancel in the ratio.