Open Inflation With Scalar-tensor Gravity

TL;DR

This paper investigates open inflation models within scalar-tensor gravity, highlighting the limitations of singular instantons without potential and suggesting the need for additional matter or potential to achieve successful inflation.

Contribution

It analyzes the Hawking-Turok open inflation model in scalar-tensor gravity and identifies the necessity of matter fields or potential for successful inflation.

Findings

Singular instantons have finite action in this model.

Gibbons-Hawking surface term vanishes, limiting its use.

Additional matter or potential is needed for successful open inflation.

Abstract

The open inflation model recently proposed by Hawking and Turok is investigated in scalar-tensor gravity context. If the dilaton-like field has no potential, the instanton of our model is singular but has a finite action. The Gibbons-Hawking surface term vanishes and hence, can not be used to make $\Omega_0$ nonzero. To obtain a successful open inflation one should introduce other matter fields or a potential for the dilaton-like fields.