Inflationary power asymmetry from primordial domain walls
  We study the asymmetric primordial fluctuations in a model of inflation in
which translational invariance is broken by a domain wall. We calculate the
corrections to the power spectrum of curvature perturbations; they are
anisotropic and contain dipole, quadrupole, and higher multipoles with
non-trivial scale-dependent amplitudes. Inspired by observations of these
multipole asymmetries in terms of two-point correlations and variance in real
space, we demonstrate that this model can explain the observed anomalous power
asymmetry of the cosmic microwave background (CMB) sky, including its
characteristic feature that the dipole dominates over higher multipoles. We
test the viability of the model and place approximate constraints on its
parameters by using observational values of dipole, quadrupole, and octopole
amplitudes of the asymmetry measured by a local-variance estimator. We find
that a configuration of the model in which the CMB sphere does not intersect
the domain wall during inflation provides a good fit to the data. We further
derive analytic expressions for the corrections to the CMB temperature
covariance matrix, or angular power spectra, which can be used in future
statistical analysis of the model in spherical harmonic space.
