1. The problem statement, all variables and given/known data Suppose that a certain accelerator can give protons a kinetic energy of 200 GeV. The rest mass of a proton is 0.938 Gev/c^2. Calculate the largest possible rest mass M0 of a particle that could be produced by the impact of one of the high-energy protons on a stationary proton in the following process: p+p --> p+p+x 2. Relevant equations Ek = γmc^2 p=γmv E^2 - (pc)^2=(mc^2)^2 Energy before = energy after P before = P after 3. The attempt at a solution Ok, I am almost positive this has to do with conservation of energy and momentum, and that is how I would end up finding the rest mass of the particle, I am just unsure of how I would know when this is at a maximum. My initial thought is that it would be when both the protons after the collision are stationary, but I have no way of proving that. Energy before = 200 Gev +0.938 + 0.938 = 201.876 GeV Energy before = γmc^2 = 0.938 GeV / √(1-v^2/c^2) I solved for v and got 0.999989c, which I can use for momentum, so P before = (0.938 GeV * 0.999c)/ √(1-(0.999989)^2) = 199.998 GeV/c After that, I could just find equations for the energy and momentum after, but I want to know first when it would be at a maximum. My professor said it had something to do with the center of mass reference frame, but I'm not sure how that would come in to play. Help?