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arXiv · 0811.4292

Matter density perturbations in modified gravity models with arbitrary coupling between matter and geometry

Savvas Nesseris
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Abstract

We consider theories with an arbitrary coupling between matter and gravity and obtain the perturbation equation of matter on subhorizon scales. Also, we derive the effective gravitational constant $G_{eff}$ and two parameters $Σ$ and $η$, which along with the perturbation equation of the matter density are useful to constrain the theory from growth factor and weak lensing observations. Finally, we use a completely solvable toy model which exhibits nontrivial phenomenology to investigate specific features of the theory. We obtain the analytic solution of the modified Friedmann equation for the scale factor $a$ in terms of time $t$ and use the age of the oldest star clusters and the primordial nucleosynthesis bounds in order to constrain the parameters of our toy model.

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Savvas Nesseris. 2009-02-10. Matter density perturbations in modified gravity models with arbitrary coupling between matter and geometry. https://doi.org/10.1103/physrevd.79.044015

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