Equilibrium partition function for nonrelativistic fluids

Understand

We construct an equilibrium partition function for a non-relativistic fluid and use it to constrain the dynamics of the system.

• The construction is based on light cone reduction, which is known to reduce the Poincare symmetry to Galilean in one lower dimension.
• We modify the constitutive relations of a relativistic fluid, and find that its symmetry broken phase - `null fluid' is equivalent to the non-relativistic fluid.
• In particular, their symmetries, thermodynamics, constitutive relations, and equilibrium partition function match exactly to all orders in derivative expansion.