https://hal-cea.archives-ouvertes.fr/cea-01318791Ballesteros, GuillermoGuillermoBallesterosIPHT - Institut de Physique Théorique - UMR CNRS 3681 - CEA - Commissariat à l'énergie atomique et aux énergies alternatives - Université Paris-Saclay - CNRS - Centre National de la Recherche ScientifiqueLuigi, PiloPiloLuigiDenis, ComelliComelliDenis Thermodynamics of perfect fluids from scalar field theoryHAL CCSD2016[PHYS.HTHE] Physics [physics]/High Energy Physics - Theory [hep-th][PHYS.GRQC] Physics [physics]/General Relativity and Quantum Cosmology [gr-qc][PHYS.HPHE] Physics [physics]/High Energy Physics - Phenomenology [hep-ph][PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]Ballesteros, GuillermoDark energy, non-linearites and effective theories - DEFT - - H20202015-10-01 - 2017-09-30 - 656794 - VALID - 2016-05-20 00:39:222021-12-13 09:16:042016-05-20 00:39:22enPreprints, Working Papers, ...1The low-energy dynamics of relativistic continuous media is given by a shift-symmetric effective theory of four scalar fields. These scalars describe the embedding in spacetime of the medium and play the role of Stuckelberg fields for spontaneously broken spatial and time translations. Perfect fluids are selected imposing a stronger symmetry group or reducing the field content to a single scalar. We explore the relation between the field theory description of perfect fluids to thermodynamics. By drawing the correspondence between the allowed operators at leading order in derivatives and the thermodynamic variables, we find that a complete thermodynamic picture requires the four Stuckelberg fields. We show that thermodynamic stability plus the null energy condition imply dynamical stability. We also argue that a consistent thermodynamic interpretation is not possible if any of the shift symmetries is explicitly broken.