Fractional fermion charges induced by vector-axial and vector gauge potentials in planar graphene-like structures

We show that fermion charge fractionalization can take place in a recently proposed chiral gauge model for graphene even in the absence of Kekul\'e distortion of the graphene honeycomb lattice. We extend the model by adding the coupling of fermions to an external magnetic field and show that the fermion charge can be fractionalized by means of only gauge potentials. It is shown that the chiral fermion charge can also have fractional value. We also relate the fractionalization of the fermion charge to the parity anomaly in an extended Quantum Electrodynamics which involves vector and vector-axial gauge fields.