http://arxiv.org/abs/1803.00014
Starting from the Gleyzes-Langlois-Piazza-Vernizzi action, we derive the most general effective theory that is invariant under internal shifts and a $\mathbb{Z}_2$ mirror symmetry in the scalar sector. Contrary to the common wisdom, this model presents a dark matter tracker previous to the dark energy domination. We show that, in an empty universe and to linear order in perturbations, the scalar mode clusters in exactly the same way as standard non-relativistic cold dark matter. This also holds for the subsector of the theory where the speed of propagation of gravitational waves equals that of light, in agreement with the recent multi-messenger observation. However, the inclusion of standard model particles introduces non-trivial couplings of the gravitational scalar mode to baryons, modifying the clustering properties. We argue that no arrange of the parameters of the model can reduce the extra scalar to precisely behave as cold dark matter.
A. Diez-Tejedor, F. Flores and G. Niz
Fri, 2 Mar 18
18/61
Comments: 11 pages, no figures
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