Clarify the anomalous origin of spin–vorticity coupling in the quark–gluon plasma

Determine whether the observed coupling of particle spin to fluid vorticity in quark–gluon plasma, exemplified by Λ-hyperon polarization, can be derived from the mixed gauge–gravitational chiral anomaly, thereby establishing an anomaly-based origin for the spin–vorticity coupling.

Background

Spin polarization of Λ hyperons has revealed strong vorticity effects in heavy-ion collisions. An axial current can be generated by the chiral separation effect at finite baryon chemical potential, suggesting a link between anomaly-induced transport and spin polarization.

The authors explicitly state that it is not yet clear if the coupling of spin to vorticity can be attributed to the mixed gauge–gravitational chiral anomaly, identifying a key theoretical gap in the microscopic origin of the effect.