Primordial quantum nonequilibrium and large-scale cosmic anomalies
  We study incomplete relaxation to quantum equilibrium at long wavelengths,
during a pre-inflationary phase, as a possible explanation for the reported
large-scale anomalies in the cosmic microwave background (CMB). Our scenario
makes use of the de Broglie-Bohm pilot-wave formulation of quantum theory, in
which the Born probability rule has a dynamical origin. The large-scale power
deficit could arise from incomplete relaxation for the amplitudes of the
primordial perturbations. We show, by numerical simulations for a spectator
scalar field, that if the pre-inflationary era is radiation dominated then the
deficit in the emerging power spectrum will have a characteristic shape (an
inverse-tangent dependence on wavenumber k, with oscillations). It is found
that our scenario is able to produce a power deficit in the observed region and
of the observed (approximate) magnitude for an appropriate choice of
cosmological parameters. We also discuss the large-scale anisotropy, which
might arise from incomplete relaxation for the phases of the primordial
perturbations. We present numerical simulations for phase relaxation, and we
show how to define characteristic scales for amplitude and phase
nonequilibrium. The extent to which the data might support our scenario is left
as a question for future work. Our results suggest that we have a potentially
viable model that might explain two apparently independent cosmic anomalies by
means of a single mechanism.
