For a Weyl semimetal with a pair of Weyl points along $z$ axis, let's consider a slab geometry that is only finite in, say, $x$ direction (infinite in $y,z$). Will the surface state still be gapless?
It is claimed without further explanation in some paper (Fig. 2b and 1st paragraph of Sec.III in PhysRevB.95.195306).
But I know for sure that the edge state is gapped in 2D quantum spin Hall insulator in a strip geometry because of the hybridization between the edges. I suppose something similar will happen in Weyl semimetal as well.
Is that gaplessness true and why?