Large Field Inflation/Quintessence and the Refined Swampland Distance Conjecture

TL;DR

The paper surveys whether large-field inflation can be realized in string theory in light of the Weak Gravity Conjecture and the Refined Swampland Distance Conjecture. It analyzes natural inflation, axion monodromy, and moduli backreaction, showing that EFT control deteriorates for trans-Planckian or axionic excursions and that an axionic version of the RSDC constrains viable field ranges. The results suggest that trans-Planckian axionic excursions are difficult to realize in UV-complete setups, with potential implications such as $r \lesssim 10^{-3}$ if the axionic RSDC holds. Quintessence faces similar challenges, indicating strong swampland pressure against axionic models of late-time acceleration as well.

Abstract

Attempts to construct string derived effective field theory models realizing large field inflation are plagued by control issues. Targeted at a broader audience, in this article we review recent progress in isolating the underlying conceptual reasons for this failure. Special emphasis is given to models of axion monodromy inflation and their relation to the Swampland Distance Conjecture. This discriminates effective actions that admit a UV completion, the landscape, from those that do not, the swampland. Since they are conceptually very similar, we also comment on implied challenges for axionic quintessence models.

Figures (7)

• Figure 1: Sketch of the Kähler moduli space of the quintic.
• Figure 2: Expected relation between proper field distance $\Theta$ and ${\rm Im} \, t$.
• Figure 3: Kähler metric for the quintic.
• Figure 4: A backreacted trajectory that destabilizes at $\Theta_c$. $\tau$ denotes a saxionic field.
• Figure 5: Large field inflation EFTs derived from UV completion.