Moduli backreaction and supersymmetry breaking in string-inspired inflation models

TL;DR

The paper investigates how heavy stabilizer fields and geometric moduli backreact on string-inspired inflation models, showing that decoupling is not guaranteed even when these fields are much heavier than the inflaton. It derives inflaton-dependent corrections to the potential and applies them to Starobinsky-like and natural inflation scenarios, finding that plateau potentials are particularly vulnerable to backreaction, while natural inflation can remain viable in some cases due to potential periodicity. It further analyzes how different moduli-stabilization schemes—no-scale, KKLT, LVS, and strong moduli stabilization—affect these backreactions, often arguing that high-scale SUSY breaking is in tension with stable plateau inflation unless strong stabilization is employed. The work highlights significant constraints on realizing consistent string-inspired inflation with heavy moduli, and it clarifies when uplift sectors can compensate backreaction, guiding future model-building in this domain.

Abstract

We emphasize the importance of effects from heavy fields on supergravity models of inflation. We study, in particular, the backreaction of stabilizer fields and geometric moduli in the presence of supersymmetry breaking. Many effects do not decouple even if those fields are much heavier than the inflaton field. We apply our results to successful models of Starobinsky-like inflation and natural inflation. In most scenarios producing a plateau potential it proves difficult to retain the flatness of the potential after backreactions are taken into account. Some of them are incompatible with non-perturbative moduli stabilization. In natural inflation there exist a number of models which are not constrained by backreactions at all. In those cases the correction terms from heavy fields have the same inflaton-dependence as the uncorrected potential, so that inflation may be possible even for very large gravitino masses.

Figures (1)

• Figure 1: Effective inflaton potential for $M = 10^{-5}$, $\xi = 1$, and $W_0$ ranging from $10^{-10}$ to $10^{-7}$. Evidently, the inflationary plateau is always destroyed for large field values, i.e., $V \to -\frac{3}{4} M^2$ as $\varphi \to \infty$.