Speaker
Description
Net-proton cumulants in the Beam Energy Scan (BES) region of heavy-ion collisions are widely used to probe critical fluctuations associated with the conjectured critical endpoint of Quantum Chromodynamics (QCD). Most existing studies, however, concentrate on the initial-state or phase-transition contributions, while the impact of hadronic rescattering on these observables has not been fully quantified. To address this gap, we construct event-by-event proton and antiproton distributions from functional renormalization group (FRG) cumulants using the maximum entropy principle, and propagate the resulting particles through the hadronic transport model SMASH. We systematically investigate how the hadronic cascade modifies net-proton cumulants at collision energies $\sqrt{s_{NN}} = 3.0,\; 3.9,\; 4.9,\; 7.2,\; \text{and}\; 7.7\ \text{GeV}$. In the canonical-ensemble framework, which enforces exact net-baryon number conservation, the higher-order cumulant signal---in particular the ratio $C_4/C_2$ at $\sqrt{s_{NN}} = 4.9\ \text{GeV}$---is strongly reduced during the early stage of the cascade; the suppression of $C_4/C_2$ reaches approximately (20%). The non-monotonic energy dependence inherited from the FRG input survives the hadronic evolution, but its magnitude is substantially modified. These results demonstrate that hadronic rescattering provides a non-negligible background effect that must be accounted for when extracting QCD critical-point signals from experimental data.
