Inflation in string theory confronts data/Les mod\`eles d'inflation en th\'eorie des cordes face aux observations

TL;DR

This paper reviews how recent CMB data constrains inflation models within string theory, highlighting the interplay between observational bounds and theoretical developments in understanding primordial inflation.

Contribution

It discusses the impact of Planck data on string-inspired inflation models and explores how observational constraints inform theoretical frameworks.

Findings

Constraints in the r-ns plane favor string-theory motivated couplings.

Data allows for searches of model-dependent features like oscillatory spectra.

Null results help bound contributions from additional sectors and couplings.

Abstract

Following the 2015 Planck release, we briefly comment on the status and some ongoing opportunities in the interface between inflationary cosmology, string theory, and CMB data. The constraints in the $r$-$n_s$ plane introduce a new parameter into inflationary cosmology relative to the simplest quadratic inflation model, in a direction which fits well with couplings to heavy fields as occurs in string theory. The precision of the data permits further searches for and constraints on additional model-dependent features, such as oscillatory $N$-spectra, a program requiring specific theoretically motivated shapes. Since the perturbations can easily be affected by additional sectors and couplings, null results can usefully bound such contributions. We also review the broader lessons string theory has contributed to our understanding of primordial inflation, and close with some approaches to a more complete framework. Published in a special volume of Comptes Rendus on Inflation: Theoretical and Observational Status.