Measurement of Helicity Parameters in Top Quark Decay

Abstract

The standard model(SM) predicts only a $g_{V-A}$ coupling in $t\to W^{+}b$ decay. However, if additional Lorentz structures exist, they can manifest themselves in high energy processes such as this via non-SM values of the helicity parameters describing $t\to W^{+}b$. Plots and tables of the values of these helicity parameters are obtained for various coupling strengths. Three phase-type ambiguities are uncovered: $g_{V-A}+g_{S+P}$ with effective-mass scale ${\Lambda }_{S+P}\sim -35GeV,g_{V-A}+g_{f_M+f_E}$ with ${\Lambda }_{f_M+f_E}\sim 53GeV$, and an arbitrary sign-flip in the $b_L$ amplitudes $A_X({\lambda }_b=-1/2)=-A_{V-A}({\lambda }_b=-1/2)$. These ambiguities are analyzed so that they might be partially resolved when experiments resume at the Fermilab Tevatron.

Comments: LateX file plus 6 tables and 9 figures; no macros