Dynamics of Nonlocal Cosmology
arXiv:0803.3399 · doi:10.1103/PhysRevD.77.123513
Abstract
Nonlocal quantum corrections to gravity have been recently proposed as a possible solution to the cosmological fine tuning problems. We study the dynamics of a class of nonlocal actions defined by a function of the inverse d'Alembertian of the Ricci scalar. Power-law and expnential functions are considered in detail, but we also show a method to reconstruct a nonlocal correction that generates a given background expansion. We find that even the simplest terms can, while involving only Planck scale constants, drive the late time acceleration without changing early cosmology. This leads to a sudden future singularity, which however may be avoided by regularizing the d'Alembertian. We also consider the Einstein frame versions of these models.
14 pages, 3 figures. V2: minor corrections