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Electromagnetic duality anomaly in curved spacetimes (1607.08879v2)
Published 29 Jul 2016 in gr-qc, hep-th, math-ph, math.MP, and quant-ph
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 presence of a background classical gravitational field with a non-trivial Chern-Pontryagin invariant, in a parallel way to the chiral anomaly for massless Dirac fermions. Among the physical consequences, the net polarization of the quantum electromagnetic field is not conserved.
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