Orbital angular momentum coupling in elastic photon-photon scattering

In this letter, we investigate the effect of orbital angular momentum (OAM) on elastic photon-photon scattering in vacuum for the first time. We define exact solutions to the vacuum electro-magnetic wave equation which carry OAM. Using those, the expected coupling between three initialwaves is derived in the framework of an effective field theory based on the Euler-Heisenberg La-grangian and shows that OAM adds a signature to the generated photons thereby greatly improvingthe signal-to-noise ratio. This forms the basis for a proposed high-power laser experiment utilizingquantum optics techniques to filter the generated photons based on their OAM state