Abstract
The source-free Maxwell action is invariant under electric-magnetic duality rotations in arbitrary spacetimes. This leads to a conserved classical Noether charge. We show that this conservation law is broken at the quantum level in the presence of a background classical gravitational field with a nontrivial Chern-Pontryagin invariant, in parallel with the chiral anomaly for massless Dirac fermions. Among the physical consequences, the net polarization of the quantum electromagnetic field is not conserved.
- Received 3 August 2016
DOI:https://doi.org/10.1103/PhysRevLett.118.111301
© 2017 American Physical Society
Physics Subject Headings (PhySH)
General Physics