Speaker
Description
In relativistic heavy ion collisions, the event-by-event mean transverse momentum ($\langle{p_{T}}\rangle$) fluctuations are sensitive to fluctuations in overlap area and reflect the nature of initial-state fluctuations in energy density. We present a cumulant framework to measure the event-by-event $\langle{p_{T}}\rangle$ fluctuations up-to $4^{\mathrm{th}}$ order which is then validated using HIJING, which is an independent source model. We observe a power law dependence for the measured cumulants of all orders as a function of charged particle multiplicity as expected from an independent source scenario. For a given $N_{\mathrm{ch}}$, the measured fluctuations show a larger magnitude for $pp$ collisions than for $p+$Pb, Pb+Pb and Xe+Xe collisions due to a bias in number of contributing sources for a given $N_{\mathrm{ch}}$. In addition, a suppression of short-range correlation was observed upon using two-subevent method in comparison to the standard method. This study provides a baseline for higher order $\langle{p_{T}}\rangle$ fluctuations arising from independent superposition of nucleon-nucleon collisions and consisting only of short-range correlations.
