Width of (a) $R_2^{\rm CI}(\Deta)$ (blue markers) and $P_2^{\rm CI}(\Deta)$ (red markers) and (b) $R_2^{\rm CD}(\Deta)$ (blue markers) and $P_2^{\rm CD}(\Deta)$ (red markers) correlation functions along $\Deta$ measured within $|\Dphi| < \pi$ in pp collisions and compared with results from p$-$Pb and Pb$-$Pb collisions as a function of $\langle {\rm d}N/{\rm d}\eta \rangle_{|\eta|< 0.5}$. Vertical bars and boxes represent statistical and systematic uncertainties, respectively.