Quenching the Chiral Magnetic Effect via the Gravitational Anomaly and Holography

Abstract

In the presence of a gravitational contribution to the chiral anomaly, the chiral magnetic effect induces an energy current proportional to the square of the temperature in equilibrium. In holography the thermal state corresponds to a black hole. We numerically study holographic quenches in which a planar shell of scalar matter falls into a black hole and raises its temperature. During the process the momentum density (energy current) is conserved. The energy current has two components, a nondissipative one induced by the anomaly and a dissipative flow component. The dissipative component can be measured via the drag it asserts on an additional auxiliary color charge. Our results indicate strong suppression very far from equilibrium.

Out-of-equilibrium chiral magnetic effect and momentum relaxation in holography

“…This means the current does need some time to build up and it even stays at its original equilibrium value for a rather long time. Qualitatively this is very similar to what has been observed in the previous study [21] based on gravitational anomaly induced chiral transport. Therefore one might speculate that it is a universal feature of anomalous transport.…”

“…The transition between both regimes appears at around τ ≈ 1. We note that this is significantly simpler than the behavior observed in [21] in the case of the gravitational anomaly induced CME, where three different regimes of fast, intermediate and slow quenches could be distinguished.…”

“…In holography out of equilibrium anomaly induced transport has been studied before in [19][20][21]. Let us briefly compare these to our approach.…”

“…[20] studied the effects of parallel magnetic and electric fields to simulate the negative magneto-resistivity out of equilibrium. Finally [21] focused on the out of equilibrium behavior of the effects induced by the gravitational anomaly. We focus on directly computing the time evolution of the response in the Vaidya background by solving partial differential equations and introduce momentum relaxation as an essentially new ingredient.…”

Membrane paradigm and RG flows for anomalous holographic theories

“…Finally, holographic systems have long been used in the study of non-equilibrium processes and the first studies regarding the gravitational anomaly have been recently published [39]. It would be interesting to see if the membrane currents we have defined, which precisely account for these anomalous hydrodynamic fluctuations at the horizon, could be used to get analytical insight over such phenomena.…”