Celestial amplitudes dual to the O(N) nonlinear sigma model

Abstract: We compute celestial amplitudes corresponding to the exact S-matrix of the 2d O(N)-symmetric nonlinear sigma model. Celestial amplitudes for two-dimensional integrable S-matrices simplify to Fourier transforms. Due to the connection between Fourier and Mellin transforms, celestial amplitudes for O(N) model are Mejer G-functions. We also prove crossing symmetry for obtained results and review simplifications for O(3) symmetry case.