TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.17.2.042
TI  - Hydrodynamic fluctuations and topological susceptibility in chiral magnetohydrodynamics
PY  - 2024/08/09
UR  - https://scipost.org/SciPostPhys.17.2.042
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 17
IS  - 2
SP  - 042
A1  - Das, Arpit
AU  - Iqbal, Nabil
AU  - Poovuttikul, Napat
AB  - Chiral magnetohydrodynamics is devoted to understanding the late-time and long-distance behavior of a system with an Adler-Bell-Jackiw anomaly at finite temperatures. The non-conservation of the axial charge is determined by the topological density $\vec{E} \cdot \vec{B}$; in a classical hydrodynamic description this decay rate can be suppressed by tuning the background magnetic field to zero. However it is in principle possible for thermal fluctuations of $\vec{E} \cdot \vec{B}$ to result in a non-conservation of the charge even at vanishing $B$-field; this would invalidate the classical hydrodynamic effective theory. We investigate this by computing the real-time susceptibility of the topological density at one-loop level in magnetohydrodynamic fluctuations, relating its low-frequency limit to the decay rate of the axial charge. We find that the frequency-dependence of this susceptibility is sufficiently soft as to leave the axial decay rate unaffected, validating the classical hydrodynamic description. We show that the susceptibility contains non-analytic frequency-dependence which is universally determined by hydrodynamic data. We comment briefly on possible connections to the recent formulation of the ABJ anomaly in terms of non-invertible symmetry.
ER  -

@Article{10.21468/SciPostPhys.17.2.042,
	title={{Hydrodynamic fluctuations and topological susceptibility in chiral magnetohydrodynamics}},
	author={Arpit Das and Nabil Iqbal and Napat Poovuttikul},
	journal={SciPost Phys.},
	volume={17},
	pages={042},
	year={2024},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.17.2.042},
	url={https://scipost.org/10.21468/SciPostPhys.17.2.042},
}