Power spectrum oscillations from Planck-suppressed operators in effective field theory motivated monodromy inflation

We consider a phenomenological model of inflation where the inflaton is the phase of a complex scalar field Φ. Planck-suppressed operators of O(f⁵/Mₚₗ) modify the geometry of the vev ⟨Φ⟩ at first order in the decay constant f, which adds a first-order periodic term to the definition of the canonically normalized inflaton φ. This correction to the inflaton induces a fixed number of extra oscillatory terms in the potential V~θᵖ. We derive the same result in a toy scenario where the vacuum ⟨Φ⟩ is an ellipse with an arbitrarily large eccentricity. These extra oscillations change the form of the power spectrum as a function of scale k and provide a possible mechanism for differentiating effective field theory motivated inflation from models where the angular shift symmetry is a gauge symmetry.