Breaking discrete symmetries in the effective field theory of inflation
  We study the phenomenon of discrete symmetry breaking during the inflationary
epoch, using a model-independent approach based on the effective field theory
of inflation. We work in a context where both time reparameterization symmetry
and spatial diffeomorphism invariance can be broken during inflation. We
determine the leading derivative operators in the quadratic action for
fluctuations that break parity and time-reversal. Within suitable
approximations, we study their consequences for the dynamics of linearized
fluctuations. Both in the scalar and tensor sectors, we show that such
operators can lead to new direction-dependent phases for the modes involved.
They do not affect the power spectra, but can have consequences for higher
correlation functions. Moreover, a small quadrupole contribution to the sound
speed can be generated.
