When a proton and an antiproton annihilate, the annihilation products are usually pions.
(a) Suppose three pions are produced. What combination(s) of π+, π−, and π0 are possible?
(b) Suppose five pions are produced. What combination(s) of π+, π−, and π0 are possible?
(c) What is the maximum number of pions that could be produced if the kinetic energies of the proton and antiproton are negligibly small? The mass of a charged pion is 0.140 GeV/ c2 and the mass of a neutral pion is 0.135 GeV/ c2.