Abstract
We revisit the issue of the correct Lagrangian description of a perfect fluid ( versus ) in relation with modified gravity theories in which galactic luminous matter couples nonminimally to the Ricci scalar. These Lagrangians are only equivalent when the fluid couples minimally to gravity and not otherwise; in the presence of nonminimal coupling they give rise to two distinct theories with different predictions.
- Received 13 November 2009
DOI:https://doi.org/10.1103/PhysRevD.80.124040
©2009 American Physical Society