Importance of tests for the complete Lorentz structure of the t→W+b vertex at hadron colliders

In a separate paper, the most general Lorentz-invariant decay-density matrix for t-->W(+)b-->(l(+)nu)b, or for t-->W+ b-->(j((d) over bar)j(u))b, is expressed in terms of eight helicity parameters. The parameters can be used to test for a variety of sources of new physics in t-->W(+)b decay. By stage-two spin-correlation techniques, percent level statistical uncertainties are typical for W-polarimetry measurements of these helicity parameters at the Fermilab Tevatron, and several mill level uncertainties are typical for W-polarimetry measurements at the CERN LHC. Lambda(b) polarimetry could be used to measure the relative phase of the b(L) and b(R) amplitudes.