# Quark

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The one exception to the confinement rule is the instance when a top quark decays with a lifetime less than ${\displaystyle 5\times 10^{-25}{\textrm {s}}}$. This decay is so rapid that there is insufficient time for the quark to hadronize, i.e., form bound hadronic states. Thus top quarks are unique in decaying as free quarks and so offer a unique opportunity to measure the properties of free quarks directly.
${\displaystyle V=\left({\begin{matrix}V_{ud}&V_{us}&V_{ub}\\V_{cd}&V_{cs}&V_{cb}\\V_{td}&V_{ts}&V_{tb}\end{matrix}}\right)=\left({\begin{matrix}1-\lambda ^{2}/2&\lambda &A\lambda ^{3}(\rho -i\eta )\\-\lambda &1-\lambda ^{2}/2&A\lambda ^{2}\\A\lambda ^{3}(1-\rho -i\eta )&-A\lambda ^{2}&1\end{matrix}}\right)}$