Black holes and θ-vacua

by Prof. Archil Kobakhidze (The University of Sydney)

Friday 14 Jun 2024, 14:00 → 15:00 Europe/Berlin

A.1.01/03 - Alps (New)

The existence of the θ−vacuum structure of Yang-Mills theories in 4-dimensional flat Minkowski spacetime is an inescapable consequence of the appearance of topologically inequivalent vacuum states connected via quantum tunnelling and the requirement of causal correlations of local operators. In this talk, I will discuss θ-vacua in the background of black hole geometry, which exhibits different (from flat Minkowski spacetime) topological as well as causal structures. In particular, I will argue that in the presence of fermion zero modes, the θ-parameter can be rotated away from the black hole's outer region, but remain non-zero on the (stretched) horizon. The horizon then can be interpreted as carrying an anomalous chiral charge and sources the 3-form gauge field. This field is capable of maintaining long-range correlations,  hence serving as a 'black hole hair'. As a result,  the (quasi)equilibrium  Hawking radiation is CP asymmetric, carrying information about the global charge accumulated on the black hole horizon.