Net-Proton Number Cumulants in Strongly and Weakly Coupled QGP

We provide a unified description of the QCD phase diagram across different energy regimes. Without any adjustable free parameters fitted to lattice or experimental data, we demonstrate that the net-proton number cumulant ratios from the Beam Energy Scan-I (BES-I) central ($0-5%$) Au+Au collision experiments at RHIC, for center-of-mass energies √s ≥ 39\,GeV, are well described by the dynamical soft-wall AdS black hole model, indicating the formation of a strongly coupled quark-gluon plasma (sQGP). We identify a critical point at \(μ_B = 247\,MeV\) or \(√s=16\,GeV\) in this model, where net-proton cumulant ratios show non-monotonic variation. However, for √s < 39\,GeV, the recent BES-II data does not exhibit the expected variation due to the critical point, suggesting instead a transition to a nearly-cold (μB T) weakly coupled QGP (wQGP) for √s < 7.7\,GeV. This prediction can be tested by the upcoming STAR Fixed-Target experimental data.