Helicity Amplitudes for Generic Multibody Particle Decays Featuring Multiple Decay Chains

Figure 1

Graphical summary of the spin state definitions associated with the decay amplitude for final particle 1 and intermediate state . The solid lines indicate the Lorentz transformation sequence involved in the writing of the helicity amplitude. Once a conventional choice for initial particle spin states is set, all the other spin states are completely specified by their Lorentz transformation sequence. Momentum labels of spin states have been suppressed to avoid cluttering the notation.