Collective Modes of Chiral Kinetic Theory in Magnetic Field

TL;DR

This paper investigates collective excitations in chiral kinetic systems under magnetic fields, revealing how chiral magnetic waves behave across different regimes and how they relate to known modes like zero sound.

Contribution

It demonstrates the emergence of chiral magnetic waves in hydrodynamic regimes and their transformation into other modes in different physical conditions.

Findings

Chiral magnetic wave exists in hydrodynamic regime with velocity set by thermodynamics.

In opposite chirality plasma, CMW becomes a diffusion mode below chirality-flipping rate.

In Fermi liquids, CMW transitions into Landau zero sound in collisionless regime.

Abstract

We study collective excitations in systems described by chiral kinetic theory in external magnetic field. We consider high-temperature weak-coupling plasma, as well as high-density Landau Fermi liquid with interaction not restricted to be weak. We show that chiral magnetic wave (CMW) emerges in hydrodynamic regime (at frequencies smaller than collision relaxation rate) and the CMW velocity is determined by thermodynamic properties only. We find that in a plasma of opposite chiralities, at frequencies smaller than the chirality-flipping rate, the CMW excitation turns into a vector-like diffusion mode. In the interacting Fermi liquid, the CMW turns into the Landau zero sound mode in the high-frequency collisionless regime.