A geometrical upper bound on the inflaton range

Abstract

We argue that in type IIB LVS string models, after including the leading order moduli stabilisation effects, the moduli space for the remaining flat directions is compact due the Calabi-Yau Kähler cone conditions. In cosmological applications, this gives an inflaton field range which is bounded from above, in analogy with recent results from the weak gravity and swampland conjectures. We support our claim by explicitly showing that it holds for all LVS vacua with h 1,1 = 3 obtained from 4-dimensional reflexive polytopes. In particular, we first search for all Calabi-Yau threefolds from the Kreuzer-Skarke list with h 1,1 = 2, 3 and 4 which allow for LVS vacua, finding several new LVS geometries which were so far unknown. We then focus on the h 1,1 = 3 cases and show that the Kähler cones of all toric hypersurface threefolds force the effective 1-dimensional LVS moduli space to be compact. We find that the moduli space size can generically be trans-Planckian only for K3 fibred examples.

De Sitter vs Quintessence in String Theory

“…If it is a pseudo‐scalar like an axion, it can avoid fifth‐force constraints, but a typical axion potential is flat enough to drive a period of accelerated expansion only if its decay constant is trans‐Planckian . This is in disagreement with recent studies of axion field ranges from string theory . On the other hand, if the quintessence field is a scalar, it is not clear how to avoid the existing stringent bounds from fifth‐forces .…”

“…In order to perform a proper study of the implications for quintessence, they have to be considered within a full moduli stabilisation mechanism. However, as mentioned above, one generically needs trans‐Planckian axionic decay constants to drive a period of accelerated expansion while recent studies of axion field ranges in string theory showed that this is very hard to achieve …”

The Swampland: Introduction and Review

“…See also []. for a review related to the distance conjecture, and [] for (an incomplete list of) an analysis of specific inflation models with respect to the distance conjecture.…”

The Asymptotic dS Swampland Conjecture ‐ a Simplified Derivation and a Potential Loophole

“…In [] the authors also point out an interesting connection between their refined dS swampland conjecture and the swampland distance conjecture . They do so by using Bousso's covariant entropy bound and thereby provide support for their refined dS swampland conjecture in the asymptotic regime, which is parametrically controlled in a strict, mathematical sense.…”