1) [10 points] Compton scattering. You might recall that when a photon scatters off a free electron, its wavelength is shifted. Derive the Compton formula. The invariants s, t and u from last week are quite useful. You are working in a frame where the photon comes in along the z direction, so p1 = (E,0,0, E/c), the electron has ps = (mc?,0,0,0) and the outgoing photon is p3 = (E',0,(E'/c)sinf, (E'/c) cos ). Recall the relation between photon en- ergy and wavelength, = he/A. I think I have the 's right in the momenta, but I put them in by hand at the end