The bulk-edge correspondence for continuous honeycomb lattices

We study bulk/edge aspects of continuous honeycomb lattices in a magnetic field. We compute the bulk index of Bloch eigenbundles: it equals $2$ or $-2$, with sign depending on nearby Dirac points and on the magnetic field. We then prove the existence of two topologically protected waves propagating along line defects. This shows the bulk/edge correspondence for our class of Hamiltonians.