Chiral phase transition in rotating quark matter with chiral imbalance: a medium separation scheme regularized NJL model study

Abstract We investigate the chiral phase transition in rotating quark matter with chiral imbalance using the two-flavor Nambu–Jona–Lasinio (NJL) model regularized by the Medium Separation Scheme (MSS). Our numerical calculations demonstrate that the chiral chemical potential $$\mu _5$$ μ 5 and angular velocity $$\omega $$ ω exert opposite effects on chiral symmetry breaking: $$\mu _5$$ μ 5 enhances the breaking, raising the pseudocritical temperature $$T_{pc}$$ T pc and sharpening the phase transition, while $$\omega $$ ω suppresses the breaking, lowering $$T_{pc}$$ T pc and smearing the transition. Notably, chiral imbalance buffers the rotation-induced softening of the phase transition – the suppression of $$T_{pc}$$ T pc by $$\omega $$ ω weakens progressively as $$\mu _5$$ μ 5 increases. The MSS predicts a monotonic increase of $$T_{pc}$$ T pc with $$\mu _5$$ μ 5 , in qualitative agreement with LQCD, resolving the discrepancy found in traditional regularization. Furthermore, the rotational suppression of $$T_{pc}$$ T pc exhibits strong radius dependence: larger rotation radii amplify the suppression due to enhanced spacetime curvature and centrifugal effects, and can even induce an abrupt drop in $$T_{pc}$$ T pc in the high-rotation region. These extended studies clarify the interplay between rotation and chiral imbalance in modulating the QCD chiral phase transition and validate the MSS as a reliable regularization framework for such extreme systems.