Quantum field theory (QFT):
Compton scattering, discovered by Arthur Holly Compton, is the scattering of a high
frequency photon after an interaction with a stationary charged particle, usually
an electron. If it results in a decrease in energy (increase in wavelength) of the
photon (which may be an X-ray or gamma ray photon), it is called the Compton effect.
Part of the energy of the photon is transferred to the recoiling electron. Inverse
Compton scattering occurs when a charged particle transfers part of its energy to a
photon.