Identifying the inflaton with primordial gravitational waves
  We explore the ability of experimental physics to uncover the underlying
structure of the gravitational Lagrangian describing inflation. While the
observable degeneracy of the inflationary parameter space is large, future
measurements of observables beyond the adiabatic and tensor two-point
functions, such as non-Gaussianity or isocurvature modes, might reduce this
degeneracy. We show that even in the absence of such observables, the range of
possible inflaton potentials can be reduced with a precision measurement of the
tensor spectral index, as might be possible with a direct detection of
primordial gravitational waves.
