Superrotations and Black Hole Pair Creation

Understand

Recent work has shown that the symmetries of classical gravitational scattering in asymptotically flat spacetimes include, at the linearized level, infinitesimal superrotations.

• These act like Virasoro generators on the celestial sphere at null infinity.
• However, due to the singularities in these generators, the physical status of finite superrotations has remained unclear.
• Here we address this issue in the context of the breaking of a cosmic string via quantum black hole pair nucleation.