On loop celestial amplitudes for gauge theory and gravity

Understand

Scattering amplitudes of massless particles in Minkowski space can be expressed in a conformal basis by Mellin transforming the momentum space amplitudes to correlation functions on the celestial sphere at null infinity.

• In this paper, we study celestial amplitudes of loop level gluons and gravitons.
• We focus on the rational amplitudes that carry all-plus and single-minus external helicities.
• Because these amplitudes are finite, they provide a concrete example of celestial amplitudes of Yang- Mills and gravity theory beyond tree level.