# Dark energy beyond quintessence: Constraints from the swampland

## TL;DR

This paper explores how higher derivative self-interactions, like the cubic Galileon term, can reconcile dark energy models with swampland criteria, challenging the constraints on standard cosmology.

## Contribution

It introduces higher derivative interactions into dark energy models, showing they can satisfy both observational data and swampland constraints, especially with cubic Galileon terms.

## Key findings

- Cubic Galileon models can meet observational and swampland criteria.
- Certain Horndeski parameter spaces remain viable under these constraints.
- Higher derivative terms expand the landscape of consistent dark energy theories.

## Abstract

The string theory swampland proposes that there is no UV-completion for an effective field theory with an exact (metastable) de Sitter vacua, thereby ruling out standard $\Lambda$CDM cosmology if the conjecture is taken seriously. The swampland criteria have also been shown to be in sharp tension with quintessence models under current and forthcoming observational bounds. As a logical next step, we introduce higher derivative self-interactions in the low-energy effective Lagrangian and show that one can satisfy observational constraints as well as the swampland criteria for some specific models. In particular, the cubic Galileon term, in the presence of an exponential potential, is examined to demonstrate that parts of the Horndeski parameter space survives the swampland and leads to viable cosmological histories.