On degenerate models of cosmic inflation
  In this article we discuss the role of current and future CMB measurements in
pinning down the model of inflation responsible for the generation of
primordial curvature perturbations. By considering a parameterization of the
effective field theory of inflation with a modified dispersion relation arising
from heavy fields, we derive the dependence of cosmological observables on the
scale of heavy physics $\Lambda_{\rm UV}$. Specifically, we show how the
$f_{\rm NL}$ non-linearity parameters are related to the phase velocity of
curvature perturbations at horizon exit, which is parameterized by
$\Lambda_{\rm UV}$. Bicep2 and Planck findings are shown to be consistent with
a value $\Lambda_{\rm UV} \sim \Lambda_{\rm GUT}$. However, we find a
degeneracy in the parameter space of inflationary models that can only be
resolved with a detailed knowledge of the shape of the non-Gaussian bispectrum.
