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

TL;DR

This paper introduces the weak magnetic effect as a dissipative correction in quark-gluon plasma, explaining the observed Lambda hyperon spin polarization and its modulation patterns in heavy-ion collisions.

Contribution

It proposes a new weak magnetic effect in quark-gluon plasma that accounts for Lambda hyperon polarization, aligning with experimental observations.

Findings

Explains Lambda spin polarization across all centrality classes.

Highlights the role of weak magnetic effect in polarization modulation.

Consistent with previous magnetic field estimates in heavy-ion collisions.

Abstract

We propose the weak magnetic effect, which emerges in quark-gluon plasma close to local thermal equilibrium as the dissipative correction to the quark phase space distribution function, as a novel contribution to the observed Lambda hyperon local spin polarization. With a finite field strength, which is consistent with previous estimate of the magnetic field in heavy-ion collisions, one is able to explain 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 the third-order modulations of the Lambda local spin polarization in experiments.