Dark Energy in String Theory
S. Parameswaran*, B.V. Bento, D. Chakraborty and I. Zavala
Published on:
August 18, 2020
Abstract
We consider various candidates for Dark Energy, motivated by string theory. Several no-go theorems push de Sitter string vacua, with $w=-1$, to the limits of theoretical control, and all known examples depend on a delicate interplay between different string theoretic ingredients. On the other hand, runaway moduli directions are ubiquitous in string theory, and could plausibly source slow-roll quintessence. We consider various candidate supergravity potentials, motivated by string theory, including single-field Kaehler potentials for bulk and local moduli, and leading superpotentials of the form $W = W_0 + A e^{-a \Phi}$ or $W = W_0 + A \Phi^p$. Conditions on the scalar potential imposed by supergravity are very restrictive, ruling out e.g. quintessence with $K=-n\ln(\Phi+\bar{\Phi})$ and $W = W_0+A \Phi^p$. Out of the examples considered, one can simultaneously satisfy $V>0$ and $\epsilon_V<1$ only for a deformation-like modulus with $K = k_0 + \frac{|\Phi|^{2n}}{k1}$ and a blow-up like modulus with $K=k_0 +\frac{(\Phi+\bar{\Phi})^{2n}}{k_1}$ when the leading order in the perturbative superpotential, $p$, is equal to $n$. We also review the scenario of Thermal Dark Energy, where thermal effects in a light hidden sector hold a scalar field up away from the minimum of its zero-temperature potential. This provides a viable model of Dark Energy with $w=-1$, consistent with known swampland conjectures, and motivates further early Thermal Dark Energy epochs with potentially observable consequences.
DOI: https://doi.org/10.22323/1.376.0123
How to cite
Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating
very compact bibliographies which can be beneficial to authors and
readers, and in "proceeding" format
which is more detailed and complete.