Fig. 3: Causality of the surface states.
From: Causal structure of interacting Weyl fermions in condensed matter systems
a A path away from the Weyl node with the surface chiral mode connecting the conduction and valence bands. b An illustration of how the surface chiral modes do not cross each other in the momentum-like case. The red (blue) curves in (b, c) represent the left (right) surface chiral mode. c An illustration of how the surface chiral modes cross each other (top panel) and become trivial surface states including the CDW (bottom panel) in the energy-like case. d The [010] surface state of Fig. 1e. The topological surface states (yellow bright curves) connect the bulk (blur regions) conduction bands to the valance bands. e The [010] surface state of Fig. 1h. The surface states become topologically trivial and open a global gap in the surface band structure.
