Quantum Hair in Electrodynamics and Gravity

TL;DR

This paper demonstrates the existence of quantum hair in electrodynamics and gravity, showing how quantum corrections can encode information about sources that classical physics cannot detect, with implications for black hole physics.

Contribution

It introduces a general formulation of quantum hair effects in electrodynamics and gravity using effective action techniques, highlighting their similarities and differences.

Findings

Quantum corrections violate classical Gauss law constraints.

Analog of black hole evaporation in QED via pair production.

Quantum hair encodes information about sources beyond classical predictions.

Abstract

We demonstrate the existence of quantum hair in electrodynamics and gravity using effective action techniques. In the case of electrodynamics we use the Euler-Heisenberg effective action while in the case of quantum gravity we use the unique effective action. We give a general formulation of these effects which applies to both theories and discuss analogies and differences between them. Furthermore, we present a QED analog to black hole evaporation. Spontaneous pair production in the external field of a ball of charge is analogous to Hawking radiation from black holes. Assuming spherical symmetry, the Gauss law prevents the external field from depending on the density profile of the ball. Quantum corrections violate these expectations, showing that quantum radiation can encode classically forbidden information about the source.