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arXiv · 2001.00772

Revisiting scalar and tensor perturbations in a nonlocal gravity

S. X. Tian·Zong-Hong Zhu
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Abstract

Nonlocal RT gravity is a successful modified gravity theory, which not only explains the late-time cosmic acceleration but also behaves well in the solar system. Previous analysis generally assumes the auxiliary field $S_i$ vanishes at the cosmic background. However, we find the background $S_i$ is proportional to $a^2$ with the expansion of the universe. Then we discuss the influence of the nonzero background $S_i$ on the cosmic background evolution, the scalar and tensor perturbations. We find the cosmic background evolution is independent of $S_i$, and the influence of the nonzero background $S_i$ on the weak field limit at solar system scales is negligible. For the tensor perturbation, we find the only possible observable effect is the influence of nonzero background $S_i$ on the LIGO gravitational wave amplitude and also luminosity distance. Future high redshift gravitational wave observations could be used to constrain the background value of $S_i$.

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S. X. Tian, Zong-Hong Zhu. 2020-01-03. Revisiting scalar and tensor perturbations in a nonlocal gravity. https://doi.org/10.1103/physrevd.100.124059

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