The Degeneracy Problem in Non-Canonical Inflation
  While attempting to connect inflationary theories to observational physics, a
potential difficulty is the degeneracy problem: a single set of observables
maps to a range of different inflaton potentials. Two important classes of
models affected by the degeneracy problem are canonical and non-canonical
models, the latter marked by the presence of a non-standard kinetic term that
generates observables beyond the scalar and tensor two-point functions on CMB
scales. The degeneracy problem is manifest when these distinguishing
observables go undetected. We quantify the size of the resulting degeneracy in
this case by studying the most well-motivated non-canonical theory having
Dirac-Born-Infeld Lagrangian. Beyond the scalar and tensor two-point functions
on CMB scales, we then consider the possible detection of equilateral
non-Gaussianity at Planck-precision and a measurement of primordial
gravitational waves from prospective space-based laser interferometers. The
former detection breaks the degeneracy with canonical inflation but results in
poor reconstruction prospects, while the latter measurement enables a
determination of $n_T$ which, while not breaking the degeneracy, can be shown
to greatly improve the non-canonical reconstruction.
