# Dynamical heredity from f(R)-bulk to braneworld: curvature dynamical constraint and f(R)-unimodular gravity

## TL;DR

This paper explores the relationship between f(R) gravity theories in bulk and brane worlds, introducing a curvature dynamical constraint to connect them, and applies this to cosmological models with dark radiation.

## Contribution

It develops the concept of curvature dynamical constraint to relate f(R)-brane and bulk theories, and derives a specific case of f(R)-unimodular gravity with cosmological applications.

## Key findings

- f(R)-brane/bulk theories can be related via curvature dynamical constraint
- Derived a dynamical version of the Gauss equation trace for f(R) theories
- Applied to cosmology, showing dark radiation effects in f(R)-unimodular gravity

## Abstract

Recently, Borzou et al. (BSSY) generalized the Shiromizu-Maeda-Sasaki (SMS) formulation to f(R)-bulks. BSSY brane projected equation carries an additional stress tensor, besides SMS correction for Einstein's theory on the brane. If we change this perspective, by requiring BSSY tensor in the geometrical side acting as f(R)-brane generator, it is possible to relate f(R)-brane/bulk theories, by using curvature dynamical constraint (CDC), a concept that we developed. Since that brane and bulk are f(R), 5/4D scalar curvatures also play a dynamical role and, thus, a dynamical version to Gauss equation trace, or CDC, must be offered. We will work yet in a specific case to obtain f(R)-unimodular gravity, formally identical with obtained by Nojiri et al. (NOO). Therefore, two applications which consider cosmological scenarios in f(R)-unimodular gravity with dark radiation correction will be offered.