UV-Protected Inflation
  In Natural Inflation, the Inflaton is a pseudo-Nambu-Goldstone boson which
acquires a mass by explicit breaking of a global shift symmetry at scale f. In
this case, for small field values, the potential is flat and stable under
radiative corrections. Nevertheless, slow roll conditions enforce f>>M_p making
the validity of the whole scenario questionable. In this letter, we show that a
coupling of the Inflaton kinetic term to the Einstein tensor allows f<<M_p by
enhancing the gravitational friction acting on the Inflaton during inflation.
This new unique interaction, a) keeps the theory perturbative in the whole
inflationary trajectory, b) preserves the tree-level shift invariance of the
pseudo-Nambu-Goldstone Boson and c) avoids the introduction of any new degrees
of freedom with respect the standard Natural Inflation.
