Higher-order transverse momentum fluctuations in heavy-ion collisions
S. Bhatta, C. Zhang, J. Jia
Abstract
In relativistic heavy-ion collisions, the event-by-event mean transverse momentum fluctuations are sensitive to overlap area and energy density fluctuations in the initial state. We present a framework to calculate ${p}_{\mathrm{T}}$ fluctuations up to fourth order using standard and subevent methods, which is validated using the HIJING model. We observe a power-law dependence for cumulants of all orders as a function of charged particle multiplicity ${N}_{\mathrm{ch}}$, consistent with a simple independent source picture. The fluctuation in $pp$ collisions is observed to be larger than for $p+\mathrm{Pb}$, Pb $+$ Pb, and Xe $+$ Xe collisions at the same ${N}_{\mathrm{ch}}$ due to bias in the number of contributing sources. The short-range correlations are greatly suppressed in the subevent method in comparison to calculations based on the standard method. This paper provides a baseline for transverse momentum fluctuations without the presence of final-state effects.