  Weyl semimetal with Weyl fermions at Fermi energy is one of the topological
materials, and is a condensed-matter realization of the relativistic fermions.
However, there are several crucial differences such as the shift of Fermi
energy, which can hinder the expected interesting physics. Chiral anomaly is a
representative nontrivial phenomenon associated with Weyl fermions, which
dictates the transfer of fermions between the Weyl fermions with opposite
chirality; it is manifested as the negative magnetoresistance. Here we
demonstrate that the magnetoresistance is robust against the deviation from the
ideal Weyl Hamiltonian such as the shifted Fermi energy and nonlinear
dispersions. We study a model with the energy dispersion containing two Weyl
nodes, and find that the magnetoresistance persists even when the Fermi level
is far away from the node, even above the saddle point that separates the two
nodes. Surprisingly, the magnetoresistance remains even after the pair
annihilation of the nodes.
