Features in the primordial power spectrum from coherent scalar-field oscillations
Saito, Ryo (Yukawa Institute for Theoretical Physics, Kyoto University)

We investigate a possible effect of a heavy scalar field on primordial fluctuations. A scalar field whose mass exceeds the Hubble scale can oscillate even in the inflationary era, and could modulate a dispersion relation of the inflaton field through derivative couplings. This modification leads to parametric resonance and generates a feature in the primordial power spectrum.