He, TempleMitra, PraharStrominger, Andrew2019-09-262016He, Temple, Prahar Mitra, and Andrew Strominger. 2016. “2D Kac-Moody Symmetry of 4D Yang-Mills Theory.” Journal of High Energy Physics 2016 (10). https://doi.org/10.1007/jhep10(2016)137.1029-84791126-6708http://nrs.harvard.edu/urn-3:HUL.InstRepos:41412214Scattering amplitudes of any four-dimensional theory with nonabelian gauge group G may be recast as two-dimensional correlation functions on the asymptotic two-sphere at null in finity. The soft gluon theorem is shown, for massless theories at the semiclassical level, to be the Ward identity of a holomorphic two-dimensional G-Kac-Moody symmetry acting on these correlation functions. Holomorphic Kac-Moody current insertions are positive helicity soft gluon insertions. The Kac-Moody transformations are a CPT invariant subgroup of gauge transformations which act nontrivially at null in finity and comprise the four-dimensional asymptotic symmetry group.en-USJournal Article2019-09-2610.1007/JHEP10(2016)137