Next-to-Next-to-Leading Order Event Generation for Top-Quark Pair Production

The production of top-quark pairs in hadronic collisions is among the most important reactions in modern particle physics phenomenology and constitutes an instrumental avenue to study the properties of the heaviest quark observed in nature. The analysis of this process at the Large Hadron Collider relies heavily on Monte Carlo simulations of the final state events, whose accuracy is challenged by the outstanding precision of experimental measurements. In this Letter we present the first matched computation of top-quark pair production at next-to-next-to-leading order in QCD with all-order radiative corrections as implemented via parton-shower simulations. Besides its intrinsic relevance for LHC phenomenology, this work also establishes an important step towards the simulation of other hadronic processes with color charges in the final state.

Figure 1

Distribution in the rapidity difference between the $t\overline{t}$ pair and the leading jet ($\mathrm{\Delta }{y}_{t\overline{t},j_1}$), in the rapidity ($y_{t_{\mathrm{av}}}$) and the average transverse-momentum ($p_{T,t_{\mathrm{av}}}$) of the top and the antitop, as well as in the rapidity ($y_{t\overline{t}}$), in the invariant mass ($m_{t\overline{t}}$) and in the transverse momentum ($p_{T,t\overline{t}}$) of the $t\overline{t}$ system. Predictions are shown for ${\mathrm{MINNLO}}_{\mathrm{PS}}$ (blue, solid), ${\mathrm{MINLO}}^{\prime }$ (black, dashed), and at NNLO (red, dashed). The black data points represent the CMS measurement at 13 TeV of Ref. [99], where the $y_{t_{\mathrm{av}}}$ and $p_{T,t_{\mathrm{av}}}$ distributions have been obtained with leptonically decaying top quarks.