Speaker
Description
We explore the validity of finite-size scaling of net-proton number cumulants as a tool to search for evidence of a critical point in the QCD phase diagram. We show that in central Au+Au collisions at $\sqrt{s_{\rm{NN}}} = 7.7$ GeV and above, the second cumulant C2 as a function of rapidity bin width follows a power-law consistent with scale invariance. We then show that for any bin width, C2 increases as a power-law with baryon chemical potential $\mu_B$. This behavior is consistent with scaling near a critical point, and our analysis identifies a range of plausible critical exponents, including mean field and 3-D Ising model critical exponents, as well as critical $\mu_{B}$ values, ranging between 500 MeV and 615 MeV which is consistent with recent theoretical expectations. To understand the origin of this apparent scale-free, power-law behavior, we perform the same analysis on simulation data from SMASH hadronic transport in the cascade mode.
