Helical magnetic effect and the chiral anomaly

In the presence of the fluid helicity $boldsymbol{v} cdot boldsymbol{omega}$, the magnetic field induces an electric current of the form $boldsymbol{j} = C_{rm HME} (boldsymbol{v} cdot boldsymbol{omega}) boldsymbol{B}$. This is the helical magnetic effect (HME). We show that for massless Dirac fermions with charge $e=1$, the transport coefficient $C_{rm HME}$ is fixed by the chiral anomaly coefficient $C=1/(2pi^2)$ as $C_{rm HME} = C/2$ independently of interactions. We show the conjecture that the coefficient of the magnetovorticity coupling for the local vector charge, $n = C_{B omega} boldsymbol{B} cdot boldsymbol{omega}$, is related to the chiral anomaly coefficient as $C_{B omega} = C/2$. We also discuss the condition for the emergence of the helical plasma instability that originates from the HME.