Reconstructing the local potential of inflation with BICEP2 data

Abstract

We locally reconstruct the inflationary potential by using the current constraints on r and ns from BICEP2 data. Assuming small and negligible αs, the inflationary potential is approximately linear in Δϕ∼ Mpl range but becomes non-linear in Δϕ∼ 10 Mpl range. However if we vary the value of αs within the range given by constraints from Planck measurement, the local reconstruction is only valid in the range of Δϕ∼ 0.4 Mpl, which challenges the inflationary background from the point of view of effective field theory. We show that, within the range of Δ ϕ ∼ 0.4 Mpl, the inflation potential can be precisely reconstructed. With the current reconstruction, we show that V(ϕ) ∼ ϕ2 and ϕ3 are consistent, while ϕ model is ruled out by 95% confidence level of the reconstructed range of potential. This sets up a strong limit of large-field inflation models.