A large number of stopped K (494) mesons are observed to decay to the 0 final state Calculate the mean distance travel led by the mesons before they decay, in the approximations that both pions have a mass of 140 MeV c 2 The mean lifetime at rest of the is 0 2 6 10 8 s ...

The finalstate pions have equal energies E ...

A large number of stopped K + (494) mesons are observed to decay to the +

Question:

A large number of stopped K⁺(494) mesons are observed to decay to the π⁺π⁰ final state. Calculate the mean distance travel-led by the π⁺ mesons before they decay, in the approximations that both pions have a mass of 140 MeV/c². The mean lifetime at rest of the π⁺ is τ₀ = 2.6 × 10⁻⁸ s.