Chemical freeze-out parameters via functional renormalization group approach
We study the freeze-out parameters in a QCD-assisted effective theory that accurately captures the quantum and in-medium effects of QCD at low energies. Functional renormalization group approach is implemented in our work to incorporate the non-perturbative quantum, thermal and density fluctuations. By analyzing the calculated baryon number susceptibility ratios $χ_{2}^{B}/χ_{1}^{B}$ and $χ_{3}^{B}/χ_{2}^{B}$, we determine the chemical freeze-out temperatures and baryon chemical potentials in cases of hard thermal or dense loop improved $μ$-dependent glue potential and $μ$-independent glue potential. We calculate the ${χ_{4}^{B}}/{χ_{2}^{B}}\, (κσ^{2})$ and ${χ_{6}^{B}}/{χ_{2}^{B}}$ along the freeze-out line for both cases. It's found that $κσ^{2}$ exhibits a nonmonotonic behavior in low collision energy region and approach to one for lower collision energy. ${χ_{6}^{B}}/{χ_{2}^{B}}$ shows a similar complicated behavior in our calculation.