Dark energy beyond quintessence: Constraints from the swampland
  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.
