Measurement of the asymmetry in angular distributions of leptons produced in dilepton $t\overline{t}$ final states in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We present measurements of asymmetries in angular distributions of leptons produced in $t\overline{t}$ events in proton-antiproton collisions at the Fermilab Tevatron Collider. We consider final states where the $W^{\pm }$ bosons from top quark and antiquark decays both decay into $\ell \nu$ ($\ell =e$, $\mu$) resulting in oppositely charged dilepton final states with accompanying jets. Using $9.7{\mathrm{fb}}^{-1}$ of integrated luminosity collected with the D0 detector, we find the asymmetries in lepton pseudorapidity compatible with predictions based on the standard model.

Figure 1

Distributions in (a) $q\times \eta$ and (b) $\Delta \eta ={\eta }_{{\ell }^{+}}-{\eta }_{{\ell }^{-}}$, for the sum of $ee$, $e\mu$ and $\mu \mu$ channels, along with predictions of the backgrounds and $t\overline{t}$ signal. The black points show data events and the error bars indicate the statistical uncertainty on the data. Predicted events in the distributions are ordered in the same way as in the legend.

Figure 2

Distributions in (a) $q\times \eta$ and (b) $\Delta \eta$, for the combined $ee$, $e\mu$, and $\mu \mu$ channels after subtraction of background and correction for selection efficiency within the acceptance. The error bars indicate the statistical uncertainty on data. The dashed lines show the predictions from mc@nlo outside the analysis acceptance.

Figure 3

Asymmetry distributions in (a) $|q\times \eta |$ and (b) $|\Delta \eta |=|{\eta }_{{\ell }^{+}}-{\eta }_{{\ell }^{-}}|$, for the combined $ee$, $e\mu$, and $\mu \mu$ channels after background subtraction and after corrections for selection efficiency. The error bars indicate statistical uncertainties on the data. The data are compared with expectations from mc@nlo and axigluon Model 1 and Model 2 as defined in the text.

Figure 4

Extrapolated $A_{\mathrm{FB}}^{\ell }$ versus $A^{\ell \ell }$ asymmetries in $t\overline{t}$ data, the predictions from mc@nlo, axigluon models, and from the latest SM NLO prediction [41]. The ellipses represent contours of total uncertainty at 1, 2, and 3 SDs on the measured result. All values are given in %. Predicted asymmetries are shown with their statistical uncertainties.