Null Fluids - A New Viewpoint of Galilean Fluids

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This article is a detailed version of our short letter `On equilibrium partition function for non-relativistic fluid' [arXiv:1505.05677] extended to include an anomalous $U(1)$ symmetry.

• We construct a relativistic system, which we call null fluid and show that it is in one-to-one correspondence with a Galilean fluid living in one lower dimension.
• The correspondence is based on light cone reduction, which is known to reduce the Poincare symmetry of a theory to Galilean in one lower dimension.
• We show that the proposed null fluid and the corresponding Galilean fluid have exactly same symmetries, thermodynamics, constitutive relations, and equilibrium partition to all orders in derivative expansion.