Top-quark decay before hadronization ($\Gamma (t\to bW)=G_F{m}_t^3|V_{tb}{|}^2(1-x{)}^2(1+2x)/(8\pi \sqrt{2})$)

Here $x=m_W^2/m_t^2$, and the tree-level decay width neglects the bottom quark mass. The open two-body W channel gives a top quark lifetime of a few $10^{-25}\mathrm{s}$, shorter than the hadronization time. A fifth-power Sargent's rule extrapolation misses this physical regime.^[ref]