Understanding the intermittency signal in RHIC-STAR data through modeling

Intermittency analysis provides a promising probe of scale-invariant density fluctuations near the QCD critical point. The intermittency measurements reported in the STAR BES-I data call for a quantitative assessment of the signal strength and a clearer physical understanding of its collision-energy dependence. In this work, we perform such a study for the STAR measurements using an improved hybrid UrQMD+CMC model, in which critical-like fluctuations are embedded into a realistic non-critical background through event-level, particle-level, and combined replacement schemes. By directly comparing the second-order factorial moment $ΔF_{2}(M)$ between model calculations and experimental data on a point-by-point basis, we constrain the effective critical-like contribution compatible with the STAR measurements without relying on scaling exponents. The STAR data at $\sqrt{s_{\mathrm{NN}}}=7.7$--$27~\mathrm{GeV}$ used for model comparison can be consistently described only by small and nearly energy-independent effective critical-like fractions. These results indicate that the current BES-I intermittency signal is weak and exhibits little collision-energy dependence, thereby favoring only a limited critical-like contribution rather than a strong critical-point-induced enhancement localized near a specific collision energy.