General tests for t→W+b couplings at hadron colliders

The modularity property of the helicity formalism is used to provide amplitude expressions and stage-two spin-correlation functions which can easily be used in direct experimental searches for electroweak symmetries and dynamics in the decay processes t→W+b and bar t→W-bar b. The formalism is used to describe the decay sequences t→W+b→(l+ν)b and t→W+b→(jbardju)b. Helicity amplitudes for t→W+b are obtained for the most general Jbarbt current. Thereby, the most general Lorentz-invariant decay density matrix for t→W+b→(l+ν)b or for t→W+b→(jbardju)b is expressed in terms of eight helicity parameters and, equivalently, in terms of the structures of the Jbarbt current. The parameters are physically defined in terms of partial-width intensities for polarized final states in t→W+b decay. The full angular distribution for the reactions q bar q and gg→t bar t→(W+b)(W-bar b)→ hor-ellipsis can be used to measure these parameters. Since this adds on spin-correlation information from the next stage of decays in the decay sequence, such an energy-angular distribution is called a stage-two spin-correlation function. copyright 1997 The American Physical Society