Revisiting In-medium QCD Effects on Spin-polarized Strange-quark Stars

We investigate the properties of exotic Strange Quark Matter (SQM) with spin polarization and the complex configuration of Strange Quark Stars (SQSs) using a phenomenological MIT Bag Model, enhanced by incorporating a QCD-informed running strange-quark mass dependent on the chemical potential. The effective mass using quasiparticle approach is utilized to understand the framework of SQM. The resulting Equation of State (EoS) is constructed for two distinct parameter sets, yielding an energy per baryon below the iron limit for stable configurations and thus supporting the Bodmer–Witten–Terazawa hypothesis that SQM could be the actual ground state of exotic matter. This framework is then used to address the Tolman–Oppenheimer–Volkoff (TOV) equations to study the effect of spin polarization on stellar properties. The model predicts that the maximum stellar mass increases with the degree of spin polarization, a result that diverges from previous constant-mass models. Furthermore, the model’s predictions for mass, radius, and surface redshift are in excellent agreement with observational constraints for the compact object Vela X-1. This agreement validates our theoretical approach and strengthens the candidacy of Vela X-1 as a Strange Quark Star. Overall, the model results highlight the importance of in-medium QCD effects in describing dense matter. Abstract Published by the Jagiellonian University 2026 authors