Effective field theory from modified gravity with massive modes
  Massive gravitational modes in effective field theories can be recovered by
extending General Relativity and taking into account generic functions of the
curvature invariants, not necessarily linear in the Ricci scalar R. In
particular, adopting the minimal extension of f(R) gravity, an effective field
theory with massive modes is straightforwardly recovered. This approach allows
to evade shortcomings like ghosts and discontinuities if a suitable choice of
expansion parameters is performed.
