Polarization Predictions for Inflationary CMB Power Spectrum Features
  We conduct a model-independent analysis of temporal features during inflation
in the large-scale CMB temperature power spectrum allowing for the possibility
of non-negligible tensor contributions. Of 20 principal components of the
inflationary history, the suppression of power at low multipoles beginning with
a glitch at multipoles $\ell \sim 20-40$ implies deviations in 2-3 of them with
2-3$\sigma$ deviations in each, with larger values reflecting cases where
tensors are allowed.If tensors are absent, the corresponding $E$-mode
polarization features follow a similar pattern but are predicted to be up to
twice as large. They offer the opportunity to soon double the significance of
inflationary features or eliminate them as an explanation of temperature
features. The tensor degeneracy with features in the temperature power spectrum
is broken not only by $B$ but also by $E$-polarization. A precision measurement
of $E$-mode polarization at multipoles from $\ell\sim 20-60$ can potentially
provide an independent constraint on tensors that is less subject to dust
foreground uncertainties.
