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arXiv · 0806.4434

Nonminimal coupling of perfect fluids to curvature

Orfeu Bertolami·Francisco S. N. Lobo·Jorge Páramos
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Abstract

In this work, we consider different forms of relativistic perfect fluid Lagrangian densities, that yield the same gravitational field equations in General Relativity. A particularly intriguing example is the case with couplings of the form $[1+f_2(R)]{\cal L}_m$, where $R$ is the scalar curvature, which induces an extra force that depends on the form of the Lagrangian density. It has been found that, considering the Lagrangian density ${\cal L}_m = p$, where $p$ is the pressure, the extra-force vanishes. We argue that this is not the unique choice for the matter Lagrangian density, and that more natural forms for ${\cal L}_m$ do not imply the vanishing of the extra-force. Particular attention is paid to the impact on the classical equivalence between different Lagrangian descriptions of a perfect fluid.

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Orfeu Bertolami, Francisco S. N. Lobo, Jorge Páramos. 2008-09-12. Nonminimal coupling of perfect fluids to curvature. https://doi.org/10.1103/physrevd.78.064036

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