The factorization property of graviton scattering amplitudes is reviewed and show to be valid only if the "natural" value of the gyromagnetic ratio $g_S=2$ is employed -- independent of spin.
Holstein, BR, "Factorization in Graviton Scattering and the “Natural” Value of the g-factor" (2006). Physics Department Faculty Publication Series. 534.
Retrieved from https://scholarworks.umass.edu/physics_faculty_pubs/534