Measurement of the $t\overline{t}$ production cross section in $2{\mathrm{fb}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using lepton plus jets events with soft muon $b$ tagging

We present a measurement of the $t\overline{t}$ production cross section in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using events containing a high transverse momentum electron or muon, three or more jets, and missing transverse energy. Events consistent with $t\overline{t}$ decay are found by identifying jets containing candidate heavy-flavor semileptonic decays to muons. The measurement uses a CDF run II data sample corresponding to $2{\mathrm{fb}}^{-1}$ of integrated luminosity. Based on 248 candidate events with three or more jets and an expected background of $79.5\pm 5.3$ events, we measure a production cross section of $9.1\pm 1.6\mathrm{pb}$.

Figure 1

Elevation view of the CDF II detector.

Figure 2

The distribution of $H_T$ for simulated $t\overline{t}$ and $W+\mathrm{\text{jets}}$ events with at least three jets.

Figure 3

The $\mathrm{SLT}\mu$ efficiency for CMU/CMP as a function of $P_T$ measured from $J/\psi$ and $Z$ data for $\mid L\mid <3.5$. The solid line is the fit to the data and the dashed lines indicate the uncertainty on the fit.

Figure 4

The $\mathrm{SLT}\mu$ efficiency for CMX arches (circles) and miniskirt/keystone (triangles) as a function of $P_T$ measured from $J/\psi$ and $Z$ data for $\mid L\mid <3.5$. The solid curves are the fits to the data and the dashed lines indicate the uncertainties on the fits.

Figure 5

The $m(K\pi \pi )-m(K\pi )$ distribution for $D^{*\pm }\to D^0{\pi }^{\pm }$, $D^0\to K^{\mp }{\pi }^{\pm }$ candidates in different $\mathrm{SLT}\mu$-track-$P_T$ bins. The line in each plot represents the fit to the sideband regions.

Figure 6

The $m(p\pi )$ distribution for ${\Lambda }^0\to p\pi$ candidates in different $\mathrm{SLT}\mu$-track-$P_T$ bins. The line in each plot represents the fit to the sideband regions.

Figure 7

The measured (triangles) and sideband-subtracted (circles) tag probabilities as a function of track $P_T$ for (a) pions, (b) kaons, and (c) protons. The uncertainties shown are statistical only.

Figure 8

The mistag probability per track as a function of track $P_T$ and detector $\eta$. The histogram binning matches that of the matrix. The uncertainties shown are statistical only. The structure in the $\eta$ distribution is an artifact of the profile of the absorber and geometrical coverage of the muon system.

Figure 9

A diagram illustrating the regions defined in the ${\mathrm{E̸}}_T$ vs I plane.

Figure 10

The ratio of observed to predicted tags as a function of ${\mathrm{E̸}}_T$ in data with a nonisolated primary lepton ($I\ge 0.2$).

Figure 11

The expected background and observed tags in $W+1$, 2, 3, and 4-or-more jets events. The expected $t\overline{t}$ contribution is normalized to the measured cross section.

Figure 12

Comparison of the jet $E_T$ distributions for tagged jets and for expectations from mistags, $W+\mathrm{\text{heavy-flavor}}$, QCD and $t\overline{t}$ events. The upper plot is for $W+1$- and 2-jet events and the lower plot for $W+3$-or-more-jets events.

Figure 13

$P_T$ of the $\mathrm{SLT}\mu$ tags compared with expectations from backgrounds and $t\overline{t}$. The upper plot is for $W+1$- and 2-jet events and the lower plot for $W+\ge 3$-jet events.

Figure 14

The distribution of $P_T$ relative to the jet axis ($P_T{}^{\mathrm{rel}}$) for tags in data, compared with expectations from backgrounds plus $t\overline{t}$. The upper plot is for 1- and 2-jet events and the lower plot for $\ge 3$-jet events.