Large Scale Power Suppression in a Multifield Landscape
  Power suppression of the cosmic microwave background on the largest
observable scales could provide valuable clues about the particle physics
underlying inflation. Here we consider the prospect of power suppression in the
context of the multifield landscape. Based on the assumption that our
observable universe emerges from a tunnelling event and that the relevant
features originate purely from inflationary dynamics, we find that the power
spectrum not only contains information on single-field dynamics, but also
places strong con- straints on all scalar fields present in the theory. We find
that the simplest single-field models giving rise to power suppression do not
generalise to multifield models in a straightforward way, as the resulting
superhorizon evolution of the curvature perturbation tends to erase any power
suppression present at horizon crossing. On the other hand, multifield effects
do present a means of generating power suppression which to our knowledge has
so far not been considered. We propose a mechanism to illustrate this, which we
dub flume inflation.
