2023/09/25 by Jean-Paul Blaizot, Blaizot, Jean-Paul
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #FOS: Physical sciences #High-Energy Particle Collisions Research #Nuclear Theory (nucl-th)
paper · pdf · doi:10.48550/arxiv.2309.14124
openalex publication_date 2023/09/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
I consider a simple set of equations that govern the expansion of boost-invariant plasmas of massless particles. These equations describe the transition from a collisionless regime at early time to hydrodynamics at late time. Their mathematical structure encompasses all versions of second order hydrodynamics. We emphasize that the apparent success of Israel-Stewart hydrodynamics at early time has little to do with ``hydrodynamics'' proper, but rather with a particular feature of Israel-Stewart equations that allows them to effectively mimic the collisionless regime.