Anomalous transport independent of gauge fields

TL;DR

This paper uncovers new universal anomalous transport effects caused by three-dimensional trace anomalies on conformally-flat spacetimes, independent of gauge fields, with potential experimental detection via background scalar fields.

Contribution

It demonstrates that trace anomalies induce gauge-field-independent anomalous transport effects, expanding understanding of anomaly-related phenomena in curved spacetime.

Findings

Anomalous currents are independent of background gauge fields.

Transport effects can be localized at interfaces by manipulating scalar fields.

The three-dimensional Hubble parameter appears in the current in cosmological settings.

Abstract

We show that three-dimensional trace anomalies lead to new universal anomalous transport effects on a conformally-flat spacetime with background scalar fields. In contrast to conventional anomalous transports in quantum chromodynamics (QCD) or quantum electrodynamics (QED), our current is independent of background gauge fields. Therefore, our anomalous transport survives even in the absence of vector-like external sources. By manipulating background fields, we suggest a setup to detect our anomalous transport. If one turns on scalar couplings in a finite interval and considers a conformal factor depending just on (conformal) time, we find anomalous transport localized at the interfaces of the interval flows perpendicularly to the interval. The magnitude of the currents is the same on the two interfaces but with opposite directions. Without the assumption on scalar couplings, and only assuming the conformal factor depending solely on (conformal) time as usually done in cosmology, one also finds the three-dimensional Hubble parameter naturally appears in our current.