Boundary Conditions of Weyl Semimetals
  We find that generic boundary conditions of Weyl semimetal is dictated by only a single real parameter, in the continuum limit. We determine how the energy dispersions (the Fermi arcs) and the wave functions of edge states depend on this parameter. Lattice models are found to be consistent with our generic observation. Furthermore, the enhanced parameter space of the boundary condition is shown to support a novel topological number. 
Koji Hashimoto, Taro Kimura, Xi Wu
cond-mat.mes-hall hep-th