Title: Thermodynamic constraints on polar active matter hydrodynamics

Abstract: In this letter we use the thermodynamics of a passive fluid to constrain transport in the corresponding active fluid which is subsequently described by the Toner-Tu equations. Acknowledging that the system fundamentally breaks boost symmetry we compel what were previously entirely phenomenological parameters in the Toner-Tu model to satisfy precise relationships among themselves. Consequently, we determine exact scalings for the transport coefficients under dynamical renormalisation group flow that reproduce the results of recent simulations.