  Correlations of conserved charges, i.e., the baryon number, electric charge
and the strangeness, have been calculated at finite temperature and chemical
potential up to the fourth order. The calculations are done in a 2+1 flavor low
energy effective theory, where quantum and thermal fluctuations are encoded
through the evolution of flow equations within the functional renormalization
group approach. Strangeness neutrality and a fixed ratio of the electric charge
to the baryon number density are implemented throughout the computation. We
find that higher-order correlations carry more sensitive critical dynamics in
comparison to the quadratic ones, and a non-monotonic dependence of the
fourth-order correlations between the baryon number and strangeness,
$-\chi^{BS}_{31}/\chi^{S}_{2}$ and $\chi^{BS}_{22}/\chi^{S}_{2}$, on the
collision energy is found.
