2) [15 points] A particle originally at rest and with initial rest energy m; = m + AFE emits a photon and decays to a particle of rest energy m. What is the energy of the photon? Check explicitly the limiting cases m >> AFE, and m = 0. ( = 1 here). Analogs of these cases are the decay of the 2P state of hydrogen to the 1S state, and the decay Higgs ~~