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

We use cosmic microwave background (CMB) and large scale structure (LSS) data to test a broad and physically well-motivated class of inflationary models: those with. at tree-level potentials ( typical in supersymmetry). The non-trivial features of the potential arise from radiative corrections which give a simple logarithmic dependence on the inflaton field, making the models very predictive. We also consider a modified scenario with new physics beyond a certain high energy cut-off showing up as non-renormalizable operators (NRO) in the inflaton field. We. find that both kinds of models 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 robust feature of these scenarios is the smallness of tensor perturbations (r less than or similar to 10(-3)). The NRO case can give a sizable running of the spectral index while achieving a suffcient number of e-folds. We use Bayesian model comparison tools to assess the relative performance of the models. We believe that these scenarios can be considered as a standard physical class of inflationary models, on a similar footing to monomial potentials.