Hydrodynamic fluctuations and topological susceptibility in chiral magnetohydrodynamics
Arpit Das, Nabil Iqbal, Napat Poovuttikul
SciPost Phys. 17, 042 (2024) · published 9 August 2024
- doi: 10.21468/SciPostPhys.17.2.042
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Abstract
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.
Authors / Affiliations: mappings to Contributors and Organizations
See all Organizations.- 1 Arpit Das,
- 2 Nabil Iqbal,
- 3 Napat Poovuttikul
- 1 University of Edinburgh
- 2 Durham University
- 3 จุฬาลงกรณ์มหาวิทยาลัย / Chulalongkorn University [CU]