Measurement of the top quark width at CDF

We present a measurement of the top quark width using 4.3/fb of data collected with the CDF detector at Fermilab. We use a two dimensional template method in the lepton+jet decay topology. The observables are the reconstructed top quark mass from the minimization of a $\chi^2$ for the overconstrained system, and the invariant mass of the two jets from the W decays, which provides an in situ improvement in the determination of the jet energy scale. We build a Feldman-Counsin (FC) confidence belt using Monte Carlo pseudo experiments to extract the top quark width from data at the $95\%$ confidence level.