  Interactions in Landau levels can stabilize new phases of matter, such as
fractionally quantized Hall states. Numerical studies of these systems mostly
require compact manifolds like the sphere or a torus. For massive dispersions,
a formalism for the lowest Landau level on the sphere was introduced by Haldane
[F.D.M. Haldane, PRL 51, 605 (1983)]. Graphene and surfaces of 3D topological
insulators, however, display massless (Dirac) dispersions, and hence require a
different description. We generalize a formalism previously developed for Dirac
electrons on the sphere in zero field to include the effect of an external,
uniform magnetic field.
