Effect of centrality selection on higher-order cumulants of net-proton multiplicity distributions in relativistic heavy-ion collisions

摘要

We studied the centrality selection effect on cumulants (up to fourth order) and the cumulants' ratios of net-proton multiplicity distributions in Au + Au collisions at s (root)s(NN )= 7.7, 19.6, and 200 GeV from the ultrarelativistic quantum molecular dynamic model. The net-proton cumulants were calculated with collision centralities by using charged-particle multiplicity from different pesudorapidity (eta) regions. By comparing the results from various collision centralities, we found that the autocorrelation effects are not significant in the results with the collision centralities "refmult-3" and "refmult-2," which use midrapidity charged particles but exclude (anti)protons and the analysis region, respectively. Furthermore, due to the contributions of spectator protons, we observed poor centrality resolution when using charged particles at forward eta regions at low energies. This work can serve as a baseline for centrality selection of future fluctuations analysis in relativistic heavy-ion collisions.