Weyl nodes, Fermi arcs, and negative longitudinal magnetoresistance from B·E pumping
Weyl semimetals host chiral (±1) band crossings (Weyl nodes). The chiral anomaly: parallel E and B pump charge between nodes at rate ∂_t(n_R − n_L) = e²E·B/(2π²ℏ²). This creates a negative longitudinal magnetoresistance — conductivity σ ∝ B² at low T. Fermi arcs connect projected Weyl nodes on the surface Brillouin zone — they're topologically protected open arcs, unlike closed Fermi surfaces.