On primordial equation of state transitions
  We revisit the physics of transitions from a general equation of state
parameter to the final stage of slow-roll inflation. We show that it is
unlikely for the modes comprising the cosmic microwave background to contain
imprints from a pre-inflationary equation of state transition and still be
consistent with observations. We accomplish this by considering observational
consistency bounds on the amplitude of excitations resulting from such a
transition. As a result, the physics which initially led to inflation likely
cannot be probed with observations of the cosmic microwave background.
Furthermore, we show that it is unlikely that equation of state transitions may
explain the observed low multipole power suppression anomaly.
