• DOI:10.1088/1475-7516/2022/02/030
• Corpus ID: 239050545

Inflation with $0 \leq c_{\rm s} \leq 1$

@inproceedings{Gorji2021InflationW,
  title={Inflation with \$0 \leq c\_\{\rm s\} \leq 1\$},
  author={Mohammad Ali Gorji and Hayato Motohashi and Shinji Mukohyama},
  year={2021}
}

• M. Gorji, H. Motohashi, S. Mukohyama
• Published 20 October 2021
• Computer Science

We investigate a novel single field inflationary scenario which allows a transition between a slow-roll k-inflation with cs of order unity and a ghost inflation with cs ' 0, where cs is the sound speed for the curvature perturbations. We unify the two phases smoothly by appropriately taking into account a higher derivative scordatura term, which is always there from the effective field theory point of view but which becomes important only in the cs ' 0 regime. The model achieves the whole range of 0 ≤ cs ≤ 1 avoiding strong coupling and gradient instability, and allows us to access the cs ' 0 regime in a self-consistent manner. We also discuss implications to the formation of primordial black holes. 1 ar X iv :2 11 0. 10 73 1v 2 [ he pth ] 8 F eb 2 02 2