Generalized relativistic second-order spin hydrodynamics from Zubarev’s nonequilibrium statistical operator

Following the approach of Harutyunyan et al. [Generalized relativistic second-order dissipative hydrodynamics: Coupling different rank tensors, Ann. Phys. (Amsterdam) 481, 170159 (2025)], where additional second-order contributions from nonlocal corrections due to two-point correlation functions of tensors of different ranks at distinct spacetime points were first derived, we similarly employ the nonequilibrium statistical operator method to extend this framework to include spin degrees of freedom. In addition to obtaining analogous extra second-order terms in the shear stress tensor, bulk viscous pressure, and charge diffusion currents resulting from such contributions, we further derive additional second-order terms originating from the same mechanism in the charge diffusion currents, rotational stress tensor, and the boost heat vector. Furthermore, we express all transport coefficients represented by two-point or three-point correlations in terms of retarded Green's functions.