Constraining Monodromy Inflation

Abstract

We use cosmic microwave background (CMB) data from the 9-year WMAP release to derive constraints on monodromy inflation, which is characterized by a linear inflaton potential with a periodic modulation. We identify two possible periodic modulations that significantly improve the fit, but it is unclear whether this improvement is associated with a "signal" or with the scatter in the measured angular power spectrum. The unmodulated potential is mildly favored by standard model selection criteria. A modulated inflationary potential can generate substantial primordial non-Gaussianity, of a specific and characteristic form. For the best-fit parameters to the WMAP angular power spectrum, the corresponding non-Gaussianity might be detectable in upcoming CMB data, allowing nontrivial consistency checks on the predictions of a modulated inflationary potential.

Version 3 -- minor editorial corrections. Version 2 -- significant revision from v1 (Overall amplitude of the potential added as a free parameter; still see two localized peaks in modulation frequency, but the best fit has significantly improved, to -2 Δlog(L) ~ -20 with respect to reference model)