Electromagnetic instantons and asymmetric Hawking radiation of black holes

Speaker: Elden Loomes (University of Sydney)
Date/Time: Wednesday 27 May 2026, 15:00
Room: MPP, Garching - A.1.01 (Alps)

Title: Electromagnetic instantons and asymmetric Hawking radiation of black holes

Abstract: The thermodynamics of semiclassical black holes is described by the Wick rotated path integral in imaginary time—the partition function on the Euclidean Schwarzschild manifold. In this talk, I will argue that the non-trivial topology of this manifold leads to additional contributions to the partition function supporting CP violation and a physical θ-term even in the simplest case of pure electromagnetism. I will show how these configurations, consisting of integer charge dyons, can be understood as windings around two independent 2-spheres in the single point compactification of the spacetime. This analysis allows us to find the complete family of classical solutions contributing to the electromagnetic partition function in the saddle-point approximation. I interpret the resulting thermal correlators, Wick rotated back into Lorentzian spacetime, as measuring an asymmetric flux between left- and right-handed polarisations in Hawking photons. I will briefly speculate as to consequences in cosmology and axion physics.