Abstract
Corrections to Einstein’s equations that become important at small curvatures are considered. The field equations are derived using a Palatini variation in which the connection and metric are varied independently. In contrast with the Einstein-Hilbert variation, which yields fourth order equations, the Palatini approach produces second order equations in the metric. The Lagrangian is examined and it is shown that it leads to equations whose solutions approach a de Sitter universe at late times. Thus, the inclusion of curvature terms in the gravitational action offers an alternative explanation for the cosmological acceleration.
- Received 1 July 2003
DOI:https://doi.org/10.1103/PhysRevD.68.063510
©2003 American Physical Society