Dark matter relic density in scalar-tensor gravity revisited
  We revisit the calculation of dark matter relic abundances in scalar-tensor
gravity using a generic form $A(\varphi_*) = e^{\beta\varphi_*^2/2}$ for the
coupling between the scalar field $\varphi_*$ and the metric, for which
detailed Big Bang Nucleosynthesis constraints are available. We find that BBN
constraints restrict the modified expansion rate in these models to be almost
degenerate with the standard expansion history at the time of dark matter
decoupling. In this case the maximum level of enhancement of the dark matter
relic density was found to be a factor of $\sim 3$, several orders of magnitude
below that found in previous investigations.
