Fourth order correlation of baryon number and electric charge as a better magnetometer of QCD

This work focuses on the fourth order correlations $\chi^{BQ}_{31}$, $\chi^{QB}_{31}$, $\chi^{BQ}_{22}$, $\chi^{BS}_{31}$, $\chi^{SB}_{31}$, $\chi^{BS}_{22}$, $\chi^{QS}_{31}$, $\chi^{SQ}_{31}$, $\chi^{QS}_{22}$, $\chi^{BQS}_{211}$, $\chi^{QBS}_{211}$, $\chi^{SBQ}_{211}$ of baryon number $B$, electric charge $Q$ and strangeness $S$ at finite temperature, magnetic field and vanishing quark chemical potential. The study is carried out in the framework of a three-flavor PNJL model, considering both cases with and without inverse magnetic catalysis effect. We find that, fourth order correlations $\chi^{BQ}_{31}$ at chiral restoration phase transition is more sensitive to the magnetic field than other second order and fourth order correlations and fluctuations, and can be served as a more effective magnetometer of QCD.