Assignment:
A pion of mass m moves with a speed u in the positive y direction in frame S with parametrs BETAu = u/c and GAMMAu = (1 - BETAu^2)^-1/2. The pion decays into two gammay rays. An observer S' moves in the positive x direction with speed v = (BETA)(c) [this is a different BETA and GAMMA than before] and detects the two photons.
A. Compute the sum of the x components of momentum in S' for the photons.
B. Compute the combined energy of the two photons in S'.
Provide complete and step by step solution for the question, use formulas.