Flat tree-level inflationary potentials in the light of cosmic microwave background and largescale structure data

Abstract

We use cosmic microwave background (CMB) and large scale structure (LSS) data to test abroad and physically well-motivated class of inflationary models: those with flat tree-levelpotentials (typical in supersymmetry). The non-trivial features of the potential arisefrom radiative corrections which give a simple logarithmic dependence on theinflaton field, making the models very predictive. We also consider a modifiedscenario with new physics beyond a certain high energy cut-off showing up asnon-renormalizable operators (NRO) in the inflaton field. We find that both kinds ofmodels fit CMB and LSS data remarkably well, with very few free parameters. Besides,many of these models naturally predict a reasonable number of e-folds. A robustfeature of these scenarios is the smallness of tensor perturbations (). The NRO case can give a sizable running of the spectral index while achieving asufficient number of e-folds. We use Bayesian model comparison tools to assess the relativeperformance of the models. We believe that these scenarios can be considered as a standardphysical class of inflationary models, on a similar footing to monomial potentials.