Higher-order transverse momentum fluctuations in heavy-ion collisions

Abstract

In relativistic heavy-ion collisions, the event-by-event mean transverse momentum fluctuations are sensitive to overlap area and energy density fluctuations in initial state. We present a framework to calculate $p_{\mathrm{T}}$ fluctuations up to $4^{\mathrm{th}}$-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 $p+$Pb, Pb+Pb and Xe+Xe collisions at the same $N_{\mathrm{ch}}$ due to bias in number of contributing sources. The short-range correlations are greatly suppressed in subevent method in comparison to calculations based on the standard method. This study provides a baseline for transverse momentum fluctuations without the presence of final state effects.

arXiv comment5 pages, 4 figures, replace with published version

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• System size and energy dependence of the mean transverse momentum fluctuations at the LHC
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• An overview of new measurements of flow, chirality, and vorticity from STAR experiment
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