Fermi point

The term Fermi point has two applications but refers to the same phenomena (special relativity):[1] For both applications count that the symmetry between particles and anti-particles in weak interactions is violated: At this point the particle energy E = cp is zero.

[3] An electron as a single particle is a fermion obeying the Pauli exclusion principle.

Fermionic systems that have a Fermi surface (FS) belong to a universality class in quantum field theory.

Any collection of fermions with weak repulsive interactions belongs to this class.

At the Fermi point, the break of symmetry can be explained by assuming a vortex or singularity will appear as a result of the spin of a fermi particle (quasiparticle, fermion) in one dimension of the three-dimensional momentum space.