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For the simplest inflation models, the recent detection of a large primordialB-mode polarization signal by the BICEP2 experiment indicates a slight tensionwith the upper limit on the tensor-to-scalar ratio, $r$, from the Plancksatellite. Here, we discuss spatially varying $r$ as a possible explanation forthis discrepancy. This idea seems attractive since it may also explain part ofthe hemispherical temperature power asymmetry seen by WMAP and Planck at largeangular scales. If these two aspects are indeed connected, the model suggeststhat in the Northern hemisphere $r$ should be much smaller, a hypothesis thatcould be confirmed with future B-mode experiments, providing a test for thestationarity of primordial tensor contributions across the sky. The BICEP2measurement furthermore rules out that a simple dipolar modulation of $r$ alonecan be responsible for the full hemispherical power asymmetry.

Linking the BICEP2 result and the hemispherical power asymmetry through spatial variation of $r$