Generalized Slow Roll for Tensors
  The recent BICEP2 detection of degree scale CMB B-mode polarization, coupled
with a deficit of observed power in large angle temperature anisotropy, suggest
that the slow-roll parameter $\epsilon_H$, the fractional variation in the
Hubble rate per efold, is both relatively large and may evolve from an even
larger value on scales greater than the horizon at recombination. The
relatively large tensor contribution implied also requires finite matching
features in the tensor power spectrum for any scalar power spectrum feature
proposed to explain anomalies in the temperature data. We extend the
generalized slow-roll approach for computing power spectra, appropriate for
such models where the slow-roll parameters vary, to tensor features where
scalar features are large. This approach also generalizes the tensor-scalar
consistency relation to be between the ratio of tensor and scalar sources and
features in the two power spectra. Features in the tensor spectrum are
generically suppressed by $\epsilon_H$ relative those in the scalar spectrum
and by the smoothness of the Hubble rate, which must obey covariant
conservation of energy, versus its derivatives. Their detection in near future
CMB data would indicate a fast roll period of inflation where $\epsilon_H$
approaches order unity, allowed but not required by inflationary explanations
of temperature anomalies.
