(No) Eternal Inflation in the Starobinsky Inflation Corrected by Higher Curvature Invariants

Round 1

Reviewer 1 Report

 

 

Comments for author File: Comments.pdf

Author Response

We referee thank you for your insights. 

"According to Ref. [24 (...)"

1) The Fig.2a actually corresponds to the model with R^{3/2}, where the delta can be large instead of the model R^4, which we guess the referee had in mind. We have introduced two different deltas to make the presentation clearer: \delta_{3/2} and \delta_4. We have also changed the plots accordingly.

 

We have also corrected all the typos.

"

Furthermore, it is not clear what is the role played by the swampland criteria in the article."

2) In [13] Tom Rudelius discusses the criteria for inflation to be non-eternal as a requirement stemming from the swampland criteria. Therefore, we have investigated a couple of possible models (possibly stemming from e.g. supergravity) checking whether they have the regions of eternal inflation and whether those regions align with the regions where the correct tensor-to-scalar ratio and scalar tilt are predicted.

I hope that this clarifies our work.

Reviewer 2 Report

In this paper, the authors study different mechanisms for achieving eternal inflation in the presence of quantum corrections. The main conclusion of this work is that several Starobinsky models require trans-Planckian inflaton masses in order for eternal inflation to be possible, concluding that the classical theory is not sufficient in these scenarios. I have found the paper to the point and, well written, and easy to read, and I think it is fit for publication once a few small points (outlined below) are addressed:

 

* It is important to specify that it is 'primordial' gravitational waves which have not yet been seen, not just gravitational waves, as the authors write in the introduction

* Below Eq.17: \phi_0 is undefined.

* There are some typos scattered throughout the paper, which should be addressed.

 

Author Response

Dear referee, we have addressed all of your comments. We have added the changes in the red colour.

Round 2

Reviewer 1 Report

I still have a question concerning the Author's reply:

The caption of fig. 2 clearly writes "the R^4 model effective potential", but it actually corresponds to the model with R^{3/2}?

Author Response

Dear referee, 

 

thank you for your quick reply. On Fig. 2 there is the effective potential for the R^4 model, while on Fig. 1 there is the potential for the R^{3/2}. You can cross-check our plots with the figures from [24], where R^4 is depicted on Fig. 3 while the R^{3/2} is depicted on Fig. 5.

 

I hope that this will be helpful for you.