Enhancement of Anomalous Boundary Current by High Temperature

TL;DR

This paper investigates how high temperatures can significantly enhance anomalous boundary currents caused by Weyl anomaly, potentially improving their experimental detectability, with different behaviors observed under various boundary conditions.

Contribution

It reveals that high temperature can amplify anomalous boundary currents, providing a new mechanism to facilitate their measurement, and clarifies the boundary-related origin of these currents.

Findings

Anomalous current scales with temperature at high temperatures.

Currents under different boundary conditions show distinct temperature dependence.

Thermal effects can enhance boundary currents without involving Weyl anomaly.

Abstract

Recently it is found that Weyl anomaly leads to novel anomalous currents in the spacetime with a boundary. However, the anomalous current is suppressed by the mass of charge carriers and the distance to the boundary, which makes it difficult to be measured. In this paper, we explore the possible mechanisms for the enhancement of anomalous currents. Interestingly, we find that the anomalous current can be significantly enhanced by the high temperature, which makes easier the experimental detection. For free theories, the anomalous current is proportional to the temperature in the high temperature limit. Note that the currents can be enhanced by thermal effects only at high temperatures. In general, this is not the case at low temperatures. For general temperatures, the absolute value of the current of Neumann boundary condition first decreases and then increases with the temperature, while the current of Dirichlet boundary condition always increases with the temperature. It should be mentioned that the enhancement does not have an anomalous nature. In fact, the so-called anomalous current in this paper is not always related to Weyl anomaly. Instead, it is an anomalous effect due to the boundary.