Radiative corrections to chiral separation effect in QED

We calculate the leading radiative corrections to the axial current in the chiral separation effect in dense QED in a magnetic field. Contrary to the conventional wisdom suggesting that the axial current should be exactly fixed by the chiral anomaly relation and is described by the topological contribution on the lowest Landau level in the free theory, we find in fact that the axial current receives nontrivial radiative corrections. The direct calculations performed to the linear order in the external magnetic field show that the nontrivial radiative corrections to the axial current are provided by the Fermi surface singularity in the fermion propagator at nonzero fermion density.

Figure 1

The leading radiative corrections to the axial current in the linear in magnetic field approximation. Solid and wavy lines correspond to the fermion and photon propagators, respectively. Double solid lines describe the axial current insertions and the external wavy lines attached to the fermion loops indicate the insertions of the external gauge field.