Form factors of self-dual gauge theory are equal to correlators of an (extended) celestial chiral algebra. This suggests that these form factors can be computed using the "bootstrap" method familiar from 2d CFTs. The method can also be applied to certain QCD amplitudes, which are built from form-factors of self-dual gauge theory.
In this paper this bootstrap method is applied to compute two-loop all-plus QCD amplitudes, for SU(N) gauge theory with certain special matter content. A closed formula is presented for all single-trace amplitudes.