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 $C=1/(2\pi^2)$ 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.
Categories: hep-th astro-ph.HE cond-mat.mes-hall hep-ph