# Reconstructing the EFT of Inflation from Cosmological Data

### Submission summary

 As Contributors: Subodh Patil · Subir Sarkar Arxiv Link: https://arxiv.org/abs/1904.00991v2 (pdf) Date accepted: 2019-09-26 Date submitted: 2019-07-16 02:00 Submitted by: Patil, Subodh Submitted to: SciPost Physics Academic field: Physics Specialties: High-Energy Physics - Theory High-Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics Approach: Theoretical

### Abstract

Reconstructions of the primordial power spectrum (PPS) of curvature perturbations from cosmic microwave background anisotropies and large-scale structure data suggest that the usually assumed power-law PPS has localised features (up to $\sim 10\%$ in amplitude), although of only marginal significance in the framework of $\Lambda$CDM cosmology. On the other hand if the underlying cosmology is assumed to be Einstein-de Sitter, larger features in the PPS (up to $\sim 20\%$) are required to accurately fit the observed acoustic peaks. Within the context of single clock inflation, we show that any given reconstruction of the PPS can be mapped on to functional parameters of the underlying effective theory of the adiabatic mode within a 2nd-order formalism, provided the best fit fractional change of the PPS, $\Delta\mathcal{P}_\mathcal{R}/\mathcal{P}_\mathcal{R}$ is such that $(\Delta\mathcal{P}_\mathcal{R}/\mathcal{P}_\mathcal{R})^3$ falls within the $1\,\sigma$ confidence interval of the reconstruction for features induced by variations of either the sound speed $c_\mathrm{s}$ or the slow-roll parameter $\epsilon$. Although there is a degeneracy amongst these functional parameters (and the models that project onto them), we can identify simple representative inflationary models that yield such features in the PPS. Thus we provide a dictionary (more accurately, a thesaurus) to go from observational data, via the reconstructed PPS, to models that reproduce them to per cent level precision.

### Ontology / Topics

See full Ontology or Topics database.

Published as SciPost Phys. 7, 049 (2019)

We have responded to the referee's queries as a comment to this article. We thank the referee for their helpful comments and questions.

### List of changes

We have added to the discussion of the results section for Lambda-CDM, as well as the Einstein- de Sitter case in addition to expanding the discussion section which elaborates on how the required small corrections to the potential that would reproduce the requisite features arise as an effective action. We have also added some references.