We prove scattering for a massless wave equation which is critical in two space dimensions. Our method combines conformal inversion with decay estimates from Struwe’s previous work on global existence of a similar equation.
"Scattering for a massless critical nonlinear wave equation in two space dimensions." Anal. PDE 7 (3) 701 - 715, 2014. https://doi.org/10.2140/apde.2014.7.701