Quintessence and the Swampland: tales of parametric and numerical control

Abstract: We provide a detailed discussion of the main theoretical and phenomenological challenges of quintessence model building in any parametric or numerically controlled regime of the moduli space of string theory. We argue that a working quintessence model requires a leading order non-supersymmetric (near) Minkowski vacuum with an axionic flat direction away from the boundary of moduli space. This axion, when lifted by subdominant non-perturbative effects, could drive hilltop quintessence only for very tuned initial conditions and a very low inflationary scale. Our analysis has a twofold implication: (1) Scenarios which are in agreement with the swampland dS conjecture, like AdS and supersymmetric Minkowski vacua, as well as runaways, cannot allow for phenomenologically viable quintessence with full computational control. This raises doubts on the validity of the swampland dS conjecture since it would imply a strong tension between quantum gravity and observations. (2) If data will prefer dynamical dark energy, axion models based on misalignment mechanisms look more promising than hilltop scenarios which are very contrived.

cosmology and nongalactic astrophysicsgeneral relativity and quantum cosmologyHEP - phenomenologyHEP - theorymathematical physics

Audience: researchers in the discipline

AnLy Strings and Fields online seminars