Lagrangian perturbation theory for modified gravity
The authors developed a Lagrangian Perturbation Theory (LPT) up to third order to compute displacement fields in modified gravity theories, especially those with scale-dependent gravity like chameleons. The work reveals key non-linear features such as force screening and frame-lagging terms. These terms are crucial for recovering General Relativity at large scales and allow for the accurate calculation of cosmological statistics using various resummation schemes.