Top quark physics at the Tevatron using $t\overline{t}$ events

The field of top-quark physics is reviewed using $t\overline{t}$ events with an emphasis on experimental techniques. The role of the top quark in the standard model of particle physics is summarized and the basic phenomenology of top-quark production and decay is introduced. Contributions from physics beyond the standard model could affect the top-quark properties or event samples. The many measurements made at the Fermilab Tevatron, which test the standard model predictions or probe for direct evidence of new physics using the top-quark event samples, are reviewed here.

Figure 1

Example of Feynman diagrams depicting SM interactions for the strong (left), electromagnetic (middle), and weak (right) forces.

Figure 2

Feynman diagrams of $p\overline{p}\to t\overline{t}$ for the $q\overline{q}$ annihilation process (left) and the gluon-gluon fusion process (middle and right).

Figure 3

Feynman diagrams of $p\overline{p}\to t\overline{t}$ production with the $t\overline{t}$ decaying to the dilepton (left), $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ (middle), and all hadronic (right) final states.

Figure 4

A cut away view of the CDF (top) and D0 (bottom) detectors.

Figure 5

Output of the NN used by CDF (left) and the BDT used by D0 (right) to determine the $t\overline{t}$ cross section in the $ljt$ channel using topological information. From 24; 72.

Figure 6

The predicted and observed number of events as a function of jet multiplicity for CDF (left) and as a function of the number of identified $b$ jets for D0 (right) both from a $t\overline{t}$ cross section analysis in the $ljt$ channel using $b$ jet identification. From 24; 72.

Figure 7

The observed ${\mathrm{E̸}}_T$ distribution compared to the SM expectations for the $t\overline{t}$ cross section measurement using CDF $dil$ events (left) and using D0 $\ell \ell$ and $\ell \tau$ events combined (right). From 11; 62.

Figure 8

The NN output distribution for QCD data (solid) and $t\overline{t}$ MC events (dashed) from CDF (left). A comparison of the likelihood distribution between data and MC using the signal purity fit from the data from D0 (right). Fits to these distributions are used to measure the $t\overline{t}$ cross section in the all-hadronic channel. From 26; 70.

Figure 9

The measured $d\sigma /d{m}_{t\overline{t}}$ from CDF (left) compared to the SM expectation. The measured $d\sigma /d{p}_T$ from D0 (right) compared to QCD calculations and various MC generators. From 13; 67.

Figure 10

The CDF determined $A_{\mathrm{fb}}$ in the $t\overline{t}$ frame, corrected to the parton level, compared to NLO predictions in bins of the $t\overline{t}$ invariant mass (left). The 95% confidence level limits on the fraction of $t\overline{t}$ produced via a $Z^{\prime }$ resonance as a function of the $Z^{\prime }$ mass (right) obtained from the D0 $A_{fb}^{t\overline{t}\mathrm{obs}}$ measurement. From 55; 36.

Figure 11

The $m_t^{\mathrm{reco}}$ distribution (left) in the CDF $ljt$ channel with the signal and background template estimates overlaid using $m_t=172\mathrm{GeV}/c^2$ and the nominal jet energy corrections for events with 1 identified $b$ jet (15). The likelihood curve from the data fit (right) in the $ljt$ channel using $L_T$ and lepton $E_T$ as top-quark mass estimators. From 29.

Figure 12

Results from $m_t$ measurements in the $ljt$ channel using the matrix element method. The two-dimensional likelihood (left) from CDF data and the data likelihood projected onto the $m_t$ axis (right) from D0. From 56; 22.

Figure 13

D0 measurement of the top-quark mass determined by comparing the measured and the SM predicted $t\overline{t}$ cross section as a function of $m_t$. From 60.

Figure 14

The $m_t^{\mathrm{reco}}$ distribution (left) for CDF events with identified $b$ jets overlaid with signal and background distributions and the posterior probability density (right) for the expected and measured ${\Gamma }_t$ determination from D0. From 12; 74.

Figure 15

The CDF $\cos {\theta }_{\ell }\cos {\theta }_d$ distribution (left) in $ljt$ events using the beam basis. The D0 $cos{\theta }_{{\ell }^{-}}\cos {\theta }_{{\ell }^{+}}$ distribution (right) in $dil$ events using the beam basis.

Figure 16

A comparison of the observed $m_{t\overline{t}}$ distribution (points) to that expected from SM sources (stacked histograms) for CDF (left) and D0 (right). From 57; 31.