Anatomy of the chiral magnetic effect in and out of equilibrium

Abstract

We identify a new contribution to the chiral magnetic conductivity at finite frequencies -the magnetization current. This allows 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 quasi-particles are emergent and the g-factor can significantly differ from 2, this opens the possibility to tune the AC chiral magnetic response. Introduction and summary -The Chiral Magnetic Effect (CME) [1] (see [2][3][4][5][6] for reviews and additional references) is the generation of electric current along an external magnetic field induced by the imbalance in the densities of right-and left-handed chiral fermions. It has been observed recently in Dirac [7,8] and Weyl [9, 10] semimetals. An evidence for CME in the quark-gluon plasma has been previously reported by high-energy heavy ion experiments at RHIC [11][12][13] and LHC [14].In the limit of a constant external magnetic field, the CME conductivity σ

Covariant chiral kinetic equation in the Wigner function approach

“…In comparison to the result of Ref. [64,66], the 1/3 contribution corresponds to that from the spin-vorticity coupling energy, while the rest 2/3 contribution corresponds to that from the magnetization current. We can show that the sQ(Ω · B) term in dx 0 /dτ in Eq.…”

“…But once including the energy corrections into the distribution functions, dx/dτ has to be modified in order to reproduce the CME and CVE, which has been done in Ref. [64,66].…”

“…An effective way of describing the kinematics of chiral fermions in phase space in the presence of chiral anomaly is the chiral kinetic equation [56,58,[61][62][63][64][65][66][67][68], which is closely related to the Berry phase and monopole in momentum space. The covariant chiral kinetic equation (CCKE) can be derived in the 4-dimensional (4D) Wigner function approach [56], from which one can derive the 3-dimensional (3D) version of the chiral kinetic equation by integration over the time component of the 4-momentum.…”

Kinetic orbital moments and nonlocal transport in disordered metals with nontrivial band geometry

“…(27), during the collision. These considerations lead to modifications 48 in the energy-conserving δ-function in Eq.…”

“…One variety of it -the dynamic Chiral Magnetic Effect (dCME) [21][22][23][24][25][26][27] -is defined as the electric current response to a slowly oscillating magnetic field, j cme (ω) = γ(ω)B(ω), where the chiral magnetic conductivity γ(ω) is the response coefficient. One can easily see that the dCME is a particular case of Eq.…”