Large tensor mode, field range bound and consistency in generalized G-inflation

TL;DR

This paper demonstrates that generalized G-inflation models can produce observable tensor modes without quantum corrections from new physics, maintaining internal consistency despite sub-Planckian field excursions and higher-derivative kinetic terms.

Contribution

It shows that potential-driven generalized G-inflation models avoid quantum corrections from new physics while generating observable tensor modes, ensuring consistency with sub-strong coupling scales.

Findings

Quantum corrections can be avoided in these models.

Observable tensor modes are produced with sub-strong coupling scale field excursions.

Higher-derivative kinetic terms prevent strong coupling during inflation.

Abstract

We systematically show that in potential driven generalized G-inflation models, quantum corrections coming from new physics at the strong coupling scale can be avoided, while producing observable tensor modes. The effective action can be approximated by the tree level action, and as a result, these models are internally consistent, despite the fact that we introduced new mass scales below the energy scale of inflation. Although observable tensor modes are produced with sub-strong coupling scale field excursions, this is not an evasion of the Lyth bound, since the models include higher-derivative non-canonical kinetic terms, and effective rescaling of the field would result in super-Planckian field excursions. We argue that the enhanced kinetic term of the inflaton screens the interactions with other fields, keeping the system weakly coupled during inflation.