Causality Constraints in Anisotropic Hydrodynamics

This paper explores the impact of anisotropy on relativistic hydrodynamics, focusing on dispersion relations and convergence. It highlights the existence of mode collisions in complex wavevector space for anisotropic systems and establishes a criterion for when these collisions impact the convergence of the hydrodynamic expansion. The paper's significance lies in its investigation of how causality, a fundamental principle, constrains the behavior of hydrodynamic models in anisotropic environments, potentially affecting their predictive power.