  Weyl semimetals are phases of matter with excitations effectively described
by massless Dirac fermions. Their critical nature makes unclear the persistence
of such phase in presence of disorder. We present a theorem ensuring the
stability of the semimetallic phase in presence of weak quasiperiodic disorder.
The proof relies on the subtle interplay of the relativistic Quantum Field
Theory description combined with number theoretical properties used in KAM
theory.
