Dark Energy and Modified Gravity in the Effective Field Theory of Large-Scale Structure

Understand

We develop an approach to compute observables beyond the linear regime of dark matter perturbations for general dark energy and modified gravity models.

• We do so by combining the Effective Field Theory of Dark Energy and Effective Field Theory of Large-Scale Structure approaches.
• In particular, we parametrize the linear and nonlinear effects of dark energy on dark matter clustering in terms of the Lagrangian terms introduced in a companion paper, focusing on Horndeski theories and assuming the quasi-static approximation.
• The Euler equation for dark matter is sourced, via the Newtonian potential, by new nonlinear vertices due to modified gravity and, as in the pure dark matter case, by the effects of short-scale physics in the form of the divergence of an effective stress tensor.