Dynamics of Nonlocal Cosmology

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 function of the inverse d'Alembertian of the Ricci scalar. Power-law and exponential 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.

Note:

14 pages, 3 figures

95.36.+x
98.80.-k
04.50.-h
correction: quantum
correction: nonlocal
expansion: acceleration
boundary condition
singularity
scaling
gravitation: scalar tensor

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Figures(6)

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