Probing inflation at small scales with the stochastic gravitational wave background

Departures of inflation from the single-field slow-roll paradigm, also known as “features”, are common in ultraviolet completions of inflation. These departures can be significant at small scales where Cosmic Microwave Background data is not constraining. I will explain how such features during inflation can be tested through their gravitational wave signal. In particular, I will show that features lead to a characteristic oscillation in the stochastic gravitational wave background. The properties of these oscillations encode information about the feature, thus giving hints about the mechanism of inflation. I will also comment on the observational prospects of observing this oscillatory signal with upcoming gravitational wave observatories such as LISA.