Gravity beyond linear perturbations in the braneworld

TL;DR

This paper reviews second-order gravitational perturbations in braneworld models, analyzing their behavior and the recovery of 4D Einstein gravity, highlighting differences across models and potential pathological issues.

Contribution

It provides a comparative analysis of second-order perturbations in various Randall-Sundrum braneworld models, emphasizing the conditions for Einstein gravity recovery.

Findings

4D Einstein gravity approximately recovered at second order

Differences in mass spectra affect perturbation behavior

Exceptional cases in two-brane models

Abstract

In the present paper, we briefly review recent studies of second-order gravitational perturbations in braneworld models. After we consider the possibility of pathological behavior of gravity at higher orders of perturbation, second-order perturbations are discussed in Randall-Sundrum braneworld models. Because the mass spectra in these braneworld models are different, we analyze them using different approaches. In the respective models, it is discussed that 4D Einstein gravity is approximately recovered at level of second-order perturbation, although there are some exceptional cases in the two-brane model.