A Holographic Construction of MHV Graviton Amplitudes in Celestial CFT

In this note, we show that tree-level MHV $n$-graviton amplitudes, when analytically continued to Klein space, can be holographically generated as the correlators of a two-dimensional conformal field theory ($2d$ CFT) in the large-$N$ semiclassical $b\to 0$ limit. This $2d$ CFT is composed of a Liouville field theory, coupled to a level-one $SO\left(N\right)$ Kac-Moody current, and a doublet of free fermions residing on ${\mathbf{C}\mathbf{P}}^1$.