Weak magnetic effect in quark-gluon plasma and local spin polarization*

Abstract We propose the weak magnetic effect, which emerges as the dissipative correction to the quark phase space distribution function in quark-gluon plasma close to local thermal equilibrium, as a novel contribution to the observed Lambda hyperon local spin polarization. A finite field strength that is consistent with previous estimates of the magnetic field in heavy-ion collisions can be used to xplain the experimentally observed Lambda local spin polarization through all centrality classes. Moreover, the weak magnetic effect plays an unambiguous role in the ordering between the second-order and third-order modulations of experimental Lambda local spin polarization.