Transients in finite inflation

We test a model of inflation with a fast-rolling kinetic-dominated initial condition against data from Planck using Markov chain Monte Carlo parameter estimation. We test both an $m^2 \phi^2$ potential and the $R+R^2$ gravity model and perform a full numerical calculation of both the scalar and tensor primordial power spectra. We find a slight (though not significant) improvement in fit for this model over the standard eternal slow-roll case.