  We study the chirally symmetric continuum model (CS-CM) of the twisted
bilayer graphene. The equation on a flat band could be interpreted as a Dirac
equation on a torus in the external non-abelian magnetic field. We prove that
the existence of the flat band implies that the wave-function has a zero and
vice verse. We found a hidden solution in the CS-CM model that has a pole
instead of a zero. Our main result is that in the basis of the flat band and
hidden wave functions the flat band could be interpreted as Landau level in the
external magnetic field. From that interpretation we show the existence of
extra flat bands in the magnetic field.
