Lectures on Celestial Holography

Abstract

These notes consist of 3 lectures on celestial holography given at the Pre-Strings school 2021. We start by reviewing how semiclassically, the subleading soft graviton theorem implies an enhancement of the Lorentz symmetry of scattering in four-dimensional asymptotically flat gravity to Virasoro. This leads to the construction of celestial amplitudes as $\mathcal{S}$-matrices computed in a basis of boost eigenstates. Both massless and massive asymptotic states are recast as insertions on the celestial sphere transforming as global conformal primaries under the Lorentz SL$(2,\mathbb{C})$. We conclude with an overview of celestial symmetries and the constraints they impose on celestial scattering.

35 pages, 5 figures

References in corpus (7)

• Evidence for a New Soft Graviton Theorem
• Gluon Amplitudes as 2d Conformal Correlators
• Loop Corrections to Soft Theorems in Gauge Theories and Gravity
• Symmetries of Celestial Amplitudes
• Notes on Conformal Soft Theorems and Recursion Relations in Gravity
• Celestial superamplitude in $\mathcal{N}=4$ SYM theory
• Gauge and Gravity Amplitudes on the Celestial Sphere

Cited by in corpus (2)

• Celestial OPE blocks
• Celestial Feynman Rules for Scalars