title: Towards hydrodynamics without an entropy current.
abstract: We present a generating functional which describes the equilibrium thermodynamic response of a relativistic system to external sources. A variational principle gives rise to constraints on the response parameters of relativistic hydrodynamics without making use of an entropy current. Our method reproduces and extends results available in the literature. It also provides a technique for efficiently computing n-point zero-frequency correlation functions within the hydrodynamic derivative expansion without the need to explicitly solve the equations of hydrodynamics.
authors.affiliation: Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada.
authors.forename: Kristan
authors.initials: K
authors.lastname: Jensen
authors.forename: Matthias
authors.initials: M
authors.lastname: Kaminski
authors.forename: Pavel
authors.initials: P
authors.lastname: Kovtun
authors.forename: René
authors.initials: R
authors.lastname: Meyer
authors.forename: Adam
authors.initials: A
authors.lastname: Ritz
authors.forename: Amos
authors.initials: A
authors.lastname: Yarom