Trend of η_2p (upper panel) and ϵ_2p (lower panel) coefficients as function of the baselines of the first measurement (differently coloured curves) and of the second measurement (x-axis). We show as dashed black curves the trends of η_1p and ϵ_1p (already shown in Fig. 3) for comparison. The redder curves in the plots correspond to the trends of η_ZBC and ϵ_ZBC, when the ZBC value is directly measured.