  An algorithm is developed for efficiently constructing the Lorentz covariant
effective three-point vertices of the decay of a particle into two daughter
particles in which all the masses and spins of the three particles can be
arbitrary. The closely-related one-to-one correspondence between the helicity
formalism and the covariant formulation is exploited for counting the number of
independent terms and identifying the basic covariant three-point vertices.
Assembling the basic operators according to the developed algorithm enables us
to construct all the covariant three-point vertices systematically.

High Energy Physics - Phenomenology;High Energy Physics - Experiment