  Selection rules and interference effects in angle resolved photoemission
spectra from twisted graphene bilayers are studied within a long wavelength
theory for the electronic structure. Using a generic model for the interlayer
coupling, we identify features in the calculated ARPES momentum distributions
that are controlled by the singularities and topological character of its long
wavelength spectrum. We distinguish spectral features that are controlled by
single-layer singularities in the spectrum, their modification by gauge
potentials in each layer generated by the interlayer coupling, and new
energy-dependent interference effects that directly probe the interlayer
coherence. The results demonstrate how the energy- and polarization- dependence
of ARPES spectra can be used to characterize the interlayer coupling in twisted
bilayer graphenes.
