Let Effective Field Theory of Inflation flow: stochastic generation of models with red/blue tensor tilt

Giulia Capurri; Nicola Bartolo; Davide Maino; Sabino Matarrese

doi:10.1088/1475-7516/2020/11/037

paper

Let Effective Field Theory of Inflation flow: stochastic generation of models with red/blue tensor tilt

arXiv:2006.10781 · doi:10.1088/1475-7516/2020/11/037

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 gravitational-wave 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 $5 \times 1 0^{4}$ realizations of inflationary scenarios that respect the Null-Energy Condition ( $ε > 0$ ) and $5 \times 1 0^{4}$ realizations that violate it ( $ε > 0$ ). In both cases, 90% of the viable models are below the most recent upper bound on the tensor-to-scalar 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 $ε > 0$ are typically characterized by $n_{t} < 0$ , whereas the vast majority of NEC-violating models presents a blue-tilted 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 gravitational-wave background.

arXiv comment24 pages, 5 figures. Replaced to match the version to appear in JCAP

Let Effective Field Theory of Inflation flow: stochastic generation of models with red/blue tensor tilt

Abstract

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