Several problems on the measured hyperorder cumulants of net-proton distributions in heavy-ion collisions

Abstract

Hyperorder cumulants $C_5/C_1$ and $C_6/C_2$ are recommended as sensitive observables to explore the QCD phase transition in heavy-ion collisions. Precisely measuring their results remains a difficult task in experiments, when employing the Centrality Bin Width Correction (CBWC) to suppress the initial volume fluctuations. Various techniques within the CBWC formula can lead to notable differences in the results. We will systematically investigate the application of the CBWC method to the measured net-proton $C_5/C_1$ and $C_6/C_2$ using the UrQMD model and Skellam-based simulations at $\sqrt{s_{NN}}$ = 11.5 GeV in Au + Au collisions. A recommended approach is proposed to calculate $C_5/C_1$ and $C_6/C_2$ in 0-40\% centrality. With statistics comparable to the RHIC Beam Energy Scan phase II (BES-II), our studies provide a baseline for analyzing net-proton $C_5/C_1$ and $C_6/C_2$ in relativistic heavy-ion collisions.