Variations of Infinite Derivative Modified Gravity. (arXiv:1902.08820v1 [hep-th])

Variations of Infinite Derivative Modified Gravity. (arXiv:1902.08820v1 [hep-th])
<a href="http://arxiv.org/find/hep-th/1/au:+Dimitrijevic_I/0/1/0/all/0/1">Ivan Dimitrijevic</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Dragovich_B/0/1/0/all/0/1">Branko Dragovich</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Rakic_Z/0/1/0/all/0/1">Zoran Rakic</a>, <a href="http://arxiv.org/find/hep-th/1/au:+Stankovic_J/0/1/0/all/0/1">Jelena Stankovic</a>

We consider nonlocal modified Einstein gravity without matter, where nonlocal
term has the form $P(R) F(Box) Q(R)$. For this model, in this paper we give
the derivation of the equations of motion in detail. This is not an easy task
and presented derivation should be useful to a researcher who wants to
investigate nonlocal gravity. Also, we present the second variation of the
related Einstein-Hilbert modified action and basics of gravity perturbations.

We consider nonlocal modified Einstein gravity without matter, where nonlocal
term has the form $P(R) F(Box) Q(R)$. For this model, in this paper we give
the derivation of the equations of motion in detail. This is not an easy task
and presented derivation should be useful to a researcher who wants to
investigate nonlocal gravity. Also, we present the second variation of the
related Einstein-Hilbert modified action and basics of gravity perturbations.

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