# f(R) and Brans-Dicke Theories and the Swampland

## TL;DR

This paper examines the constraints imposed by the Swampland conjectures on $f(R)$ and Brans-Dicke theories, identifying allowed parameter ranges and implications for inflation and dark energy models.

## Contribution

It derives the Swampland conjecture conditions within $f(R)$ and Brans-Dicke frameworks and analyzes their impact on model viability and parameter space.

## Key findings

- Large portion of parameter space is excluded by Swampland constraints.
- Allowed ranges for $R$ are identified for inflation and dark energy models.
- Perfect fluid domination can satisfy Swampland conditions more easily.

## Abstract

We discuss the viability of $f(R)$ and Brans-Dicke theories of gravity in light of the recent Swampland conjectures. We show that in the case of perfect fluid domination the swampland conjecture conditions may be easily satisfied and therefore we focus on the constraints in the vacuum theory. We derive the conditions for the swampland conjectures in $f(R)$ and Brans-Dicke framework, and find that a large portion of the parameter space is not allowed. Furthermore, we analyze particular $f(R)$ models of inflation and dark energy and in their case we set the allowed range of $R$.