Chiral edge states on spheres for lattice domain wall fermions

Recently Weyl edge states on manifolds in dimension d + 1 with a connected d-dimensional boundary were proposed as candidates for lattice regularization of chiral gauge theories, for even d. The examples considered to date include solid cylinders in any odd dimension, and the 3 ball with boundary S2. Here we consider the general case of a (d + 1)-dimensional ball for any even d and show that the theory for the edge states on Sd describe a conventional Weyl fermion on a sphere with half-integer momenta. A possible advantage of such theories is that they can be discretized by a square lattice without breaking the underlying discrete hypercubic symmetry.