Importance of Tests for the Complete Lorentz Structure of the t --> W+ b vertex at Hadron Colliders

Abstract

The most general Lorentz-invariant decay-density-matrix for $t\to W^{+}b\to (l^{+}ν)b$, or for $t\to W^{+}b\to (j_{\bar d}j_u)b$, is expressed in terms of eight helicity parameters. The parameters are physically defined in terms of partial-width-intensities for polarized-final-states in $t\to W^{+}b$ decay. The parameters are the partial width, the $b$ quark's chirality parameter $ξ$, the $W^+$ polarimetry parameter $σ$, a "pre-SSB" test parameter $ζ$, and four $W_{L}$-$W_{T}$ interference parameters $η$, $η^{'}$, $ω$, $ω^{'}$ which test for $\tilde T_{FS}$ violation. They can be used to test for non-CKM-type CP violation, anomalous $Γ_{L,T}$'s, top weak magnetism, weak electricity, and second-class currents. By stage-two spin-correlation techniques, percent level statistical uncertainites are typical for measurements at the Tevatron, and several mill level uncertainites are typical at the LHC.