Let Effective Field Theory of inflation flow: stochastic generation of models with red/blue tensor tilt
Abstract
We extend the method of Flow Equations to the Effective Field Theory framework of inflation, in order to investigate the observable predictions of a very broad class of inflationary models. Focusing our attention on the gravitationalwave sector, we derive a general expression for the consistency relation for effective models and provide a numerical implementation which allows to study how the generated models populate the (r,n_{t}) plane. We analyse 5 × 10^{4} realizations of inflationary scenarios that respect the NullEnergy Condition (epsilon > 0) and 5 × 10^{4} realizations that violate it (epsilon < 0). In both cases, 90 % of the viable models are below the most recent upper bound on the tensortoscalar ratio from Planck and BICEP2/Keck Array BK15 data: r_{0.002} < 0.056 at 95 % CL . We find that general EFT inflationary models with epsilon > 0 are typically characterized by n_{t} < 0, whereas the vast majority of NECviolating models presents a bluetilted spectrum (n_{t} > 0). Since a blue tensor spectral index implies more power on small scales, this result is of considerable interest in view of a possible direct detection of the primordial gravitationalwave background.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 November 2020
 DOI:
 10.1088/14757516/2020/11/037
 arXiv:
 arXiv:2006.10781
 Bibcode:
 2020JCAP...11..037C
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 24 pages, 5 figures. Replaced to match the version to appear in JCAP