Forms of action for perfect fluid in General Relativity and mimetic gravity

Abstract

We consider various forms of action allowing us to describe a perfect fluid in the framework of General Relativity. First we consider a potential motion without pressure. Starting from an action in terms of the current density vector built similarly to the action of a single particle, we build a series of equivalent actions through various changes of variables. The results are then generalized to the cases of motion with vorticity and the presence of pressure. The obtained forms of action are compared to the previously known variants. We discuss the possibilities to use the obtained results to formulate the theories containing a description of a perfect fluid. A new form of action is proposed for mimetic gravity, which allows a motion with vorticity for mimetic matter as a perfect fluid.

LaTeX, 14 pages. Some discussions and references were added in this version

References in corpus (6)

• Mimetic gravity: a review of recent developments and applications to cosmology and astrophysics
• Cosmology with Mimetic Matter
• Mimetic dark matter, ghost instability and a mimetic tensor-vector-scalar gravity
• Imperfect Dark Matter
• General Relativity à la string: a progress report
• Clebsch Potentials in the Variational Principle for a Perfect Fluid

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