Measurement of the differential top cross section ($d\sigma$/$dM_{t\bar t}$) at CDF

We present a measurement of the $t\overline{t}$ differential cross section, $d\sigma/dM_{t\overline{t}}$, at $\sqrt{s}= 1.96$~TeV using approximately $1.9~fb^{-1}$ of data collected with the CDF II Detector at the Fermilab Tevatron. We select events in the $W+\geq4$~jets sample with displaced secondary vertices from jets with heavy-flavor decays. We use a regularized unfolding technique to correct the reconstructed invariant mass distribution back to the true distribution. We see no evidence of inconsistency with the standard model, with an observed p-value of 0.45.