Chemical freeze-out parameters via a nonperturbative QCD approach

By analyzing the calculated baryon number susceptibility ratios ${\chi_{1}^{B}}/{\chi_{2}^{B}}$ and ${\chi_{3}^{B}}/{\chi_{1}^{B}}$ in two-flavor system via Dyson-Schwinger equation approach of QCD, we determine chemical freeze-out temperature potential cases both thermodynamic limit finite size. We calculate center-of-mass energy dependence ${\chi_{4}^{B}}/{\chi_{2}^{B}}\, (\kappa \sigma^{2})$ at line find an excellent agreement with experimental data when taking into account size effect. Our calculations indicate that $\kappa \sigma^{2}$ exhibits a nonmonotonic behavior lower collision region. also predict ${\chi_{6}^{B}}/{\chi_{2}^{B}}$ is nonmonotonic.