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arXiv · 1612.05553

Dark Matter Relics and the Expansion Rate in Scalar-Tensor Theories

Bhaskar Dutta·Esteban Jimenez·Ivonne Zavala
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Abstract

We study the impact of a modified expansion rate on the dark matter relic abundance in a class of scalar-tensor theories. The scalar-tensor theories we consider are motivated from string theory constructions, which have conformal as well as disformally coupled matter to the scalar. We investigate the effects of such a conformal coupling to the dark matter relic abundance for a wide range of initial conditions, masses and cross-sections. We find that exploiting all possible initial conditions, the annihilation cross-section required to satisfy the dark matter content can differ from the thermal average cross-section in the standard case. We also study the expansion rate in the disformal case and find that physically relevant solutions require a nontrivial relation between the conformal and disformal functions. We study the effects of the disformal coupling in an explicit example where the disformal function is quadratic.

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Bhaskar Dutta, Esteban Jimenez, Ivonne Zavala. 2017-06-03. Dark Matter Relics and the Expansion Rate in Scalar-Tensor Theories. https://doi.org/10.1088/1475-7516%2F2017%2F06%2F032

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