Cosmological perturbations in nonlocal gravity
After discovery of accelerating expansion of the Universe, there has been a renewed interest in gravity modification. One of promising approaches is nonlocal modification with the scalar curvature R in the action replaced by a suitable function F (R, \Box), where \Box is the Laplace-Beltrami operator. In particular we analyze the modification with nonlocal term H(R) F(\Box) G(R) where F(\Box) is an analytic function. Also we will discuss perturbations of this model with several backgrounds.
This is joint work with Branko Dragovich, Jelena Stankovic and Zoran Rakic.
 T. Biswas, T. Koivisto, A. Mazumdar, "Towards a resolution of the cosmological singularity in non-local higher derivative theories of gravity", JCAP 1011 (2010) 008,
 I. Dimitrijevic, B. Dragovich, J. Grujic and Z. Rakic, "On modified gravity", in Lie Theory and Its Applications in Physics ed. V. Dobrev, Springer Proc. Math. 36 (2013) 251 arXiv:1202.2352.