The effective action of superrotation modes

PIRSA ID: 21060126
Series: Quantum Gravity
Event Type: Seminar
Scientific Area(s):
Quantum Gravity
End date:
  • Jakob Salzer, Harvard University

Asymptotically flat spacetimes are invariant under an infinite-dimensional symmetry group comprised of superrotations and supertranslations. These symmetries are spontaneously broken, leading to an infinite degeneracy of gravitational vacua in asymptotically flat spacetimes. Starting from an analysis of four-dimensional asymptotically flat gravity in first order formulation, I will describe how superrotation parametrization modes labelling distinct superrotation vacua are governed by an Alekseev–Shatashvili action on the celestial sphere. I will also comment on a recent construction of a two-dimensional effective action for the Goldstone modes of broken supertranslation invariance.