Anatomy of the chiral magnetic effect in and out of equilibrium

We identify a new contribution to the chiral magnetic conductivity at finite frequencies—the magnetization current. This allows us to quantitatively reproduce the known field-theoretic time-dependent (AC) chiral magnetic response in terms of kinetic theory. We evaluate the corresponding AC chiral magnetic conductivity in two-flavor QCD plasma at weak coupling. The magnetization current results from the spin response of chiral quasiparticles to magnetic field, and is thus proportional to the quasiparticle’s $g$-factor. In condensed matter systems, where the chiral quasiparticles are emergent and the $g$-factor can significantly differ from 2, this opens up the possibility of tuning the AC chiral magnetic response.

Figure 1

The real (blue) and imaginary (red) parts of $\sigma (\omega )$ in two-flavor pQCD with ${\alpha }_s=0.2$ and ${\mu }_A/T=0.1$ (solid lines). The dotted curves are the results in the $\mathrm{AdS}/\mathrm{CFT}$ correspondence [16].