= The momentum transfer is q = ph - Ph, where p is the hadron momentum after the collision. This relationship holds for the time as well as the space components, i.e., for the 4-vectors. Thus, we have q = p + p - 2ph. Ph 2mc 2ph Ph, where m is the mass of the hadron. Since ph = Ph - q, we have q 2m - 2ph (Ph-9) = 2ph q. - = Show that q2=-2ph q for elastic scattering. Here p and q are 4-vectors with phq Engo/c2 - Ph q and ph is the initial momentum of the hadron. (See Section 6.10).