Testing kinetically coupled inflation models with CMB distortions
  Inflation scenarios kinetically coupled with the Einstein tensor have been
widely studied. They can be consistent with current observational data. Future
experiments on the measurement on CMB distortions will potentially extend
information about the scalar spectrum to small scales $1 \Mpc^{-1} \lesssim k
\lesssim 2 \times 10^4 \Mpc^{-1}$. By taking the sensitivity of the PIXIE
experiment as the criterion, we perform a model-oriented analysis of the
observational prospects of spectral distortions for kinetically coupled
inflation. There are five models that possibly generate a detectable level of
distortions, among the 49 single-field inflation models listed in Ref.
\cite{Martin2013a}. These models are: hybrid inflation in the valley (VHI),
non-canonical K\"{a}hler inflation (NCKI), generalized MSSM inflation (GMSSMI),
generalized renormalization point inflation (GRIPI), and running-mass inflation
(RMI). Each of these models can satisfy the Planck constraints on spectral tilt
and lead to increase power on scales relevant for CMB distortions in a tuned
region of their parameter space. The existence of kinetic coupling suppresses
the value of the model parameters with mass dimension for VHI, GMSSMI, and
GRIPI, such that these three models can be in agreement with their theoretical
considerations. However, the tuned regions for all these models fail to satisfy
the constraints on tensor modes.
