Multiplicity fluctuations of net protons on the hydrodynamic freeze-out surface

This proceeding briefly summarizes our recent work on calculating the correlated fluctuations of net protons on the hydrodynamic freeze-out surface near the QCD critical point. For both Poisson and Binomial baselines, our calculations could roughly reproduce the energy dependent cumulant C4 and κσ2 of net protons, but always over-predict C2 and C3 due to the positive contributions from the static critical fluctuations.