Dark energy in the swampland
By Lavinia Heisenberg, M. Bartelmann, Robert Brandenberger, Alexandre Refregier. Physical Review D, 2018
157 citations recorded by the source corpus.
In this article, we study the implications of string swampland criteria for dark energy in view of ongoing and future cosmological observations. If string theory should be the ultimate quantum gravity theory, there is evidence that exact de Sitter solutions with a positive cosmological constant cannot describe the fate of the late-time universe. Even though cosmological models with dark energy given by a scalar field $\ensuremath{\pi}$ evolving in time are not in direct tension with string theory, they have to satisfy the swampland criteria $|\mathrm{\ensuremath{\Delta}}\ensuremath{\pi}|ld\ensuremath{\sim}\mathcal{O}(1)$ and $|{V}^{\ensuremath{'}}|/Vgc\ensuremath{\sim}\mathcal{O}(1)$, where $V$ is the scalar field potential. In view of the restrictive implications that the swampland criteria have on dark energy, we investigate the accuracy needed for future observations to tightly constrain standard dark-energy models. We find that current $3\text{\ensuremath{-}}\ensuremath{\sigma}$ constraints with $c\ensuremath{\lesssim}1.35$ are still well in agreement with the string swampland criteria. However, stage-4 surveys such as Euclid, LSST, and DESI, tightly constraining the equation of state $w(z)$, will start putting surviving quintessence models into tensions with the string swampland criteria by demanding $cl0.4$. We further investigate whether any idealized futuristic survey will ever be able to give a decisive answer to the question whether the cosmological constant would be preferred over a time-evolving dark-energy model within the swampland criteria. Hypothetical surveys with a reduction in the uncertainties by a factor of $\ensuremath{\sim}20$ compared to Euclid would be necessary to reveal strong tension between quintessence models obeying the string swampland criteria and observations by pushing the allowed values down to $cl0.1$. In view of such perspectives, there will be fundamental observational limitations with future surveys.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/540fe241a422562a125aa96b10a2300ffadf65ac
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Citations in the corpus
- The Swampland: Introduction and Review (2019, background): “The cosmological bounds from dark energy on the de Sitter conjecture were further developed in [562–567], and on the refined de Sitter conjecture in [171,568–571].”