Top panel: Measurements of $[ (v_{2}\{2\}^{2}-v_{2}\{4\}^{2})/(v_{2}\{2\}^{2}+v_{2}\{4\}^{2})]^{1/2}$ in p-Pb and Pb-Pb collisions. The measurements of $v_{2}\{2\}$ are obtained with a $|\Delta \eta| > 1.4$ gap. Only statistical errors are shown as these dominate the uncertainty.
Bottom panel: $\sigma_{v2} / \langle v_{2} \rangle$ obtained from the same $v_{2}\{2\}$ and $v_{2}\{4\}$ measurements assuming a Bessel-Gaussian distribution.