The measurement uses a matrix element integration method to calculate a tt likelihood, employing a Quasi-Monte Carlo integration, which enables us to take into account effects due to finite detector angular resolution and quark mass effects.We calculate a tt likelihood as a 2-D function of the top pole mass m t and ∆ JES , where ∆ JES parameterizes the uncertainty in our knowledge of the jet energy scale;it is a shift applied to all jet energies in units of the jet-dependent systematic error.By introducing ∆ JES into the likelihood, we can use the information contained in W boson decays to constrain ∆ JES and reduce error due to this uncertainty. We use a neural network discriminant to identify events likely to be background, and apply a cut on the peak value of individual event likelihoods to reduce the effect of badly reconstructed events. This measurement uses a total of 4.3 fb −1 of integrated luminosity, requiring events with a lepton, large E T , and exactly four high-energy jets in the pseudorapidity range |η| < 2.0, of which at least one must be tagged as coming from a b quark. In total, we observe 738 events before and 630 events after 1 applying the likelihood cut, and measure m t = 172.6 ± 0.9 (stat.) ± 0.7 (JES) ± 1.1 (syst.) GeV/c 2 , or m t = 172.6 ± 1.6 (tot.) GeV/c 2 .