Forays into the dark side of the swamp
Motivated by the swampland conjectures, we study the cosmological signatures of a quintessence potential which induces time variation in the low-energy effective field theory. After deriving the evolution of the quintessence field, we illustrate its possible ramifications by exploring putative imprints in a number of directions of particle phenomenology. We first show that a dark matter self-interaction rate increasing with time gives a novel way of reconciling the large self-interactions required to address small-scale structure issues with the constraint coming from clusters. Next, we study the effects of kinetic mixing variation during the radiation-dominated era on freeze-in dark matter production. Last, we elucidate quintessence effects on the restoration of the electroweak symmetry at finite temperature and the lifetime of the electroweak vacuum through a modification of the effective Higgs mass and quartic coupling.