Measurement of the $t\overline{t}$ Production Cross Section in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We measure the $t\overline{t}$ production cross section in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ in the $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ channel. Two complementary methods discriminate between signal and background: $b$ tagging and a kinematic likelihood discriminant. Based on $0.9{\mathrm{fb}}^{-1}$ of data collected by the D0 detector at the Fermilab Tevatron Collider, we measure ${\sigma }_{t\overline{t}}=7.62\pm 0.85\mathrm{pb}$, assuming the current world average $m_t=172.6\mathrm{GeV}$. We compare our cross section measurement with theory predictions to determine a value for the top-quark mass of $170\pm 7\mathrm{GeV}$.

Figure 1

Jet multiplicity spectra for $e+\mathrm{\text{jets}}$ and $\mu +\mathrm{\text{jets}}$ events (a) with one $b$-tagged jet and (b) with at least two $b$-tagged jets. The histograms show (from top to bottom) the contributions from $t\overline{t}$ production and from backgrounds with prompt leptons and without prompt leptons.

Figure 2

Likelihood discriminant distributions for $e+\mathrm{\text{jets}}$ and $\mu +\mathrm{\text{jets}}$ events (a) with 3 jets and (b) with at least 4 jets. The histograms show (from top to bottom) the contributions from $t\overline{t}$ production and from backgrounds with prompt leptons and without prompt leptons.

Figure 3

Comparison of measured cross section and theory prediction versus top-quark mass.