Celestial amplitudes and BMS algebra (Angelos Fotopoulos; QG webinar)

Zoom seminar by Angelos Fotopoulos (Northeastern University and Wentworth Institute of Technology).
Title: "Celestial amplitudes and BMS algebra"

I will discuss celestial amplitudes in Yang-Mills and gravity. A Mellin transform of 4D amplitudes recasts them in the form of conformal correlators in 2D. The proposed holographic correspondence between the 4D theory and its 2D Celestial CFT dual is explored using field theoretical methods. I will show how to use soft and collinear theorems of the  Einstein-Yang- Mills theory to derive the OPEs of the operators associated to massless particles. The symmetry underlying the CCFT is expected to be the extended BMS symmetry of (asymptotically) flat space­ time. I will discuss the realization of the extended BMS symmetry in the CCFT picture for both the purely bosonic and its N=1 supersymmetric extension. The algebra of the supersymmetric BMS generators agrees with expectations based on earlier work on the asymptotic symmetry group of supergravity.  Time permitting, I will discuss recent progress in the double-copy/KLT relations in CCFT.