Lower-bound estimate of the energy density times the formation time $\tau$ in pp, \pPb, and \PbPb\ collisions at $\sqrtSnn = 5.02$ \TeV as a function of the number of participating nucleons . The transverse area is calculated as the total area of overlap between participating nucleons using Eq. ???. The open circles are from \PbPb{} collisions at $\sqrtSnn = 2.76$ \TeV and calculated via direct measurements of $\ET$ . A fit to a power law $a\Npart^p$ is shown with best-fit parameter values $a=0.8\pm0.2$ GeV/(fm$^2$$c$) and $p=0.44\pm0.07$, and $\chi^2/dof = 1.2/16$. |  |