The fully differential top decay distribution

Abstract

Abstract We write down the four-dimensional fully differential decay distribution for the top quark decay $$t \rightarrow Wb \rightarrow \ell \nu b$$ t → W b → ℓ ν b . We discuss how its eight physical parameters can be measured, either with a global fit or with the use of selected one-dimensional distributions and asymmetries. We give expressions for the top decay amplitudes for a general tbW interaction, and show how the untangled measurement of the two components of the fraction of longitudinal W bosons – those with b quark helicities of 1 / 2 and $$-1/2$$ - 1 / 2 , respectively – could improve the precision of a global fit to the tbW vertex.

Keywords

• Charged Lepton
• Angular Momentum Conservation
• Spin Observable
• Helicity Fraction
• Boson Spin