Cosmological perturbations in nonlocal higherderivative gravity
Abstract
We study cosmological perturbations in a nonlocal higherderivative model of gravity introduced by Biswas, Mazumdar and Siegel. We extend previous work, which had focused on classical scalar perturbations around a cosine hyperbolic bounce solution, in three ways. First, we point out the existence of a Starobinsky solution in this model, which is more attractive from a phenomenological point of view (even though it has no bounce). Second, we study classical vector and tensor pertuxsxrbations. Third, we show how to quantize scalar and tensor perturbations in a de Sitter phase (for choices of parameters such that the model is ghostfree). Our results show that the model is wellbehaved at this level, and are very similar to corresponding results in local f(R) models. In particular, for the Starobinsky solution of nonlocal higherderivative gravity, we find the same tensortoscalar ratio as for the conventional Starobinsky model.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 November 2014
 DOI:
 10.1088/14757516/2014/11/022
 arXiv:
 arXiv:1407.4982
 Bibcode:
 2014JCAP...11..022C
 Keywords:

 High Energy Physics  Theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 28 pages