Two-field axion inflation and the swampland constraint in the flux-scaling scenario

Abstract

Based on the flux-scaling scenario we study a model consisting on Type IIB string theory compactified on a Calabi-Yau manifold with a frozen complex structure in the presence of generic fluxes. The model contains (meta)stable Minkowski and de Sitter vacua as well as inflationary directions driven by two independent linear combination of axions. Due to a numerical control by fluxes, we show that cosmological parameters as the spectral index, tensor-to-scalar ratio and non-Gaussianities can be kept within observed bounds while preserving the desired hierarchies on physical scales. Moreover we compute the deviation of the inflationary trajectories from geodesics on field space in terms of the fluxes showing that for some regions, they fulfill the recent proposed swampland criterion for multi-field scenarios.

Figures (7)

• Figure 1: Plot of a) scalar potential and b) stable inflationary trajectories for $f = 1/40$, $h = 1/50$, $q = -1/17$ and $\lambda = 1/50$.
• Figure 2: Slow--roll parameters $\epsilon$(solid line) and $\eta$ (dashed line) for a) trajectory I, b) trajectory II and c) trajectory III.
• Figure 3: Plot of spectral index $n_s$ for a) trajectory I, b) trajectory II and c) trajectory III.
• Figure 4: Plot of the tensor to scalar ratio $r$ for a) trajectory I, b) trajectory II and c) trajectory III.
• Figure 5: Plot of non-Gaussianities for a) trajectory I, b) trajectory II and c) trajectory III.