Combination of measurements of the top-quark pair production cross section from the Tevatron Collider

We combine six measurements of the inclusive top-quark pair ($t\overline{t}$) production cross section (${\sigma }_{t\overline{t}}$) from data collected with the CDF and D0 detectors at the Fermilab Tevatron with proton-antiproton collisions at $\sqrt{s}=1.96\mathrm{TeV}$. The data correspond to integrated luminosities of up to $8.8{\mathrm{fb}}^{-1}$. We obtain a value of ${\sigma }_{t\overline{t}}=7.60\pm 0.41\mathrm{pb}$ for a top-quark mass of $m_t=172.5\mathrm{GeV}$. The contributions to the uncertainty are 0.20 pb from statistical sources, 0.29 pb from systematic sources, and 0.21 pb from the uncertainty on the integrated luminosity. The result is in good agreement with the standard model expectation of $7.35_{-0.33}^{+0.28}\mathrm{pb}$ at next-to-next-to-leading order and next-to-next-to leading logarithms in perturbative QCD.

Figure 1

The six input ${\sigma }_{t\overline{t}}$ measurements from the CDF and D0 experiments, along with the CDF-only and D0-only combination results, and their combination for the Tevatron result. The total uncertainty, as well as the statistical and systematic uncertainties are shown. The D0 dilepton and $\ell +\text{jets}$ measurements using constrained nuisance parameters are presented in their published form indicating only their total uncertainties. The inner (red) bars reflect statistical uncertainties while the outer (blue) bars show the total uncertainties on each measurement.

Figure 2

The combined ${\sigma }_{t\overline{t}}$ at the Tevatron as a function of $m_t$ (black line), as expressed by Eq. (1), compared to the prediction (narrower red line) at $\mathrm{NNLO}+\mathrm{NNLL}$ in perturbative QCD [24]. The dashed lines show the total uncertainty on the result (black dashed lines enclosing shaded region) and the prediction (narrower red dashed lines).