UrQMD Study of the Effects of Centrality Definitions on Higher Moments of Net Protons at RHIC

Abstract

A study using UrQMD is presented concerning the higher moments of net protons from Au+Au collisions at 7.7, 11.5, 14.6, 19.6, 27, 39, 62.4, and 200 GeV, concentrating on $C_4/C_2=\kappa {\sigma }^2$. Higher moments of net protons are predicted to be a sensitive probe of the critical point of QCD. At the QCD critical point, particular ratios of the moments of net protons are predicted to differ from the Poisson baseline. Recently STAR has published the higher moments of net protons for Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV. UrQMD quantitatively reproduces STAR's measured $C_4/C_2=\kappa {\sigma }^2$ for net protons for all Au+Au collisions more central than 30\% and at all centralities for $\sqrt{s_{\mathrm{NN}}}$ = 7.7 and 11.5 GeV. The effects are investigated of three different centrality definitions on the values of $C_4/C_2=\kappa {\sigma }^2$ from UrQMD calculations including the impact parameter given by UrQMD. It is shown that using a centrality definition based on multiplicity to calculate the higher moments of net protons gives a biased answer for $C_4/C_2=\kappa {\sigma }^2$, except in the most central bin (0-5\%).

7 pages, 7 figures

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Cited by in corpus (14)

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• Resonance decay effect on conserved number fluctuations in a hadron resonance gas model
• Rapidity dependence of proton cumulants and correlation functions
• Centrality selection effect on higher-order cumulants of net-proton multiplicity distributions in relativistic heavy-ion collisions
• Effects of centrality fluctuation and deuteron formation on proton number cumulant in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV from JAM model
• Effect of correlations on cumulants in heavy-ion collisions
• Fluctuations of identified particle yields using the ν dyn variable at energies available at the BNL Relativistic Heavy Ion Collider
• Experimental results on charge fluctuations in heavy-ion collisions
• Beam energy dependence of cumulants of the net-baryon, net-charge and deuteron multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}=3.0-5.0$ GeV
• Understanding the negative binomial multiplicity fluctuations in relativistic heavy ion collisions
• Efficiency corrections for mutually inclusive variables and particle identification effect for mixed-cumulants in heavy-ion collisions
• Statistical method in quark combination model
• Energy and system size dependence of strongly intensive fluctuation measures in heavy-ion collisions at FAIR energies
• Study of diffusion coefficients of identified particles at energies available at BNL Relativistic Heavy Ion Collider