  We present a derivation of coherent helicity amplitudes for a particle
decaying into multifinal states with nonzero spins. The results show that the
coherent amplitudes introduce additional rotations to transform the helicities
into a consistent helicity system, which allows us to add helicity amplitudes
for different decay chains coherently. These rotations may have significant
effects on the interference between the decay chains in the partial wave
analysis.
