Natural millicharged inflation

We construct a natural inflation model with the inflaton as a linear combination of the fifth components of Abelian gauge fields in a five-dimensional theory. A seesaw mechanism is introduced to provide a natural millicharge for matter fields under one combination of the gauge symmetries. As a result, the effective decay constant of the inflaton field can be above the Planck scale with all scales in the model below the Planck scale. Our model predicts a tensor-to-scalar ratio r between 0.033 and 0.125 for 60 e-folds and a reheating temperature of a few 10(11) GeV.