I am not sure this is the right topic for these questions. They are for the people who are familiar with Compton scattering. Let [tex]\Theta[/tex] be the angle that the trajectory of the scattered photon makes with the trajectory of the incident photon. Suppose [tex]\Theta[/tex] is zero. Does that mean that the incident photon misses the electron (or some target charged particle) altogether or it hits the electron but does not interact with the electron at all? I can imagine the incident photon usually misses the electron, but surely there should be some hits now and then. Therefore, Compton forward transmission (CFT - not really scattering) as I shall term it should happen. The formula predicts in this case that there shall be no redshift. I find this hard to believe. It's though the cue ball goes right through the 8 ball into the pool pocket without changing the position of the 8 ball at all. Has anyone done any detailed QFT analysis of CFT? If so, what were the results? As for experiments, I suppose it would be very hard to measure any redshift in CFT.