Flat Space Amplitudes and Conformal Symmetry of the Celestial Sphere

Sabrina Pasterski, Shu-Heng Shao, Andrew Strominger

The four-dimensional (4D) Lorentz group $SL(2,\mathbb{C})$ acts as the two-dimensional (2D) global conformal group on the celestial sphere at infinity where asymptotic 4D scatterin…