Ξ− collective flow and equation of state of dense nuclear matter in heavy-ion collisions

The collective flow of double-strangeness ^- baryons and its sensitivity to the equation of state (EoS) of dense nuclear matter are investigated in Au+Au collisions at s₍₍=4--10 GeV using a pure hadronic transport model (AMPT-HC). By simulating semicentral collisions (b=4--8. 5 fm) with soft (K₀=230 MeV) and stiff (K₀=380 MeV) EoS parameterizations, we analyze the central evolution of compression density, ^- production mechanisms, and collective flow observables. The results demonstrate that ^- production, concentrated in the midrapidity region, exhibits stronger sensitivity to the EoS stiffness than single-strangeness hadrons, owing to its dependence on multistep strangeness-exchange processes in high-density regions. The directed flow (v₁) and elliptic flow (v₂) of ^- further reveal distinctive EoS-driven dynamics: a stiff EoS generates stronger anisotropic pressure gradients during compression, leading to a pronounced v₁ slope at midrapidity and enhanced v₂ at high transverse momenta (pₓ>1. 00. 16em{0ex}GeV/c). These observables, complementary in probing cumulative yields and intensive kinematics, highlight ^- as a unique probe of the high-density EoS near the QCD phase boundary. The findings underscore the critical role of ^- collective flow in constraining the nuclear matter EoS at suprasaturation densities.