Optimizing future experimental probes of inflation
  The discovery of many novel realizations of the inflationary universe
paradigm has led to a degeneracy problem: many different inflationary
Lagrangians generate the same perturbation spectra. Resolving this problem
requires the future discovery of additional observables, beyond the scalar
adiabatic and tensor two-point functions on CMB scales. One important source of
degeneracy arises in models where the density perturbation is generated by a
non-inflationary degree of freedom, for example, through curvatons or modulated
reheating. We consider the curvaton scenario as representative of this class,
and analyze the degeneracy with single field, canonical inflation that results
if the curvaton goes undetected by future observations. We perform Monte Carlo
potential reconstructions in the absence of distinguishing observables, such as
non-Gaussiantities or isocurvature modes. The resulting degeneracy is
considerable and the improved measurements of spectral parameters from future
probes like CMBPol, offer little to better the situation. Given a
degeneracy-breaking observation, the observables must still be inverted to
obtain the inflationary potential, with different observations resulting in
reconstructions of varying quality. We find that a future detection of
isocurvature modes or a precision measurement of the tensor spectral index will
enable the most successful reconstructions in the presence of curvatons.
