Relativistic Hydrodynamic Attractors with Broken Symmetries: Non-Conformal and Non-Homogeneous

TL;DR

This paper demonstrates the existence of out-of-equilibrium hydrodynamic attractor solutions in non-conformal, non-homogeneous systems, expanding the applicability of hydrodynamics beyond near-equilibrium conditions.

Contribution

It shows that hydrodynamic attractors are present in more general settings, including non-conformal and spatially non-homogeneous systems, which was not established before.

Findings

Attractor solutions exist in non-conformal kinetic theory.

Attractors are found in spatially non-homogeneous systems.

Implications for interpreting experimental data in high-energy collisions.

Abstract

Standard textbooks will state that hydrodynamics requires near-equilibrium to be applicable. Recently, however, out-of-equilibrium attractor solutions for hydrodynamics have been found in kinetic theory and holography in systems with a high degree of symmetry, suggesting the possibility of a genuine out-of-equilibrium formulation of hydrodynamics. This work demonstrates that attractor solutions also occur in non-conformal kinetic theory and spatially non-homogeneous systems, potentially having important implications for the interpretation of experimental data in heavy-ion and proton-proton collisions and relativistic fluid dynamics as a whole.