$\pt$ broadening, $\Delta\langle p^2_{\rm T}\rangle$, as a function of $\langle N^{\rm mult}_{\rm coll}\rangle$ at backward (blue circles) and forward (red squares) rapidity. The boxes centered at $\Delta\langle p^2_{\rm T}\rangle=0$ represent the total uncertainties of $\langle p^2_{\rm T}\rangle_{pp}$ interpolated to $\sqrt{s}=5.02$ TeV. The theoretical calculations are from Refs.[72-74].