 W boson decay to a quark pair

Ignoring accessible quark masses and strong corrections, the W boson flavor width is $\Gamma (W^{+}\to q{\bar{q}}^{\prime })=N_c{G}_F{M}_W^3|V_{q{q}^{\prime }}{|}^2/(6\pi \sqrt{2})$. The CKM matrix fixes the flavor factor, while the color multiplicity in a decay width supplies $N_c=3$. Only the up and charm rows are accessible for an on-shell W boson, giving a total hadronic width $G_F{M}_W^3/(\pi \sqrt{2})$ by row unitarity.