Top-quark pair production at the LHC: Fully differential QCD predictions at NNLO

TL;DR

The paper develops a fully differential NNLO QCD calculation for top-quark pair production at hadron colliders using the $q_T$ subtraction method in the Matrix framework. It delivers NNLO predictions for a range of single- and double-differential distributions at 13 TeV and validates them against CMS data, exploring different scale choices including dynamical scales. The NNLO results reduce theoretical uncertainties and generally improve agreement with experiment, while electroweak corrections remain subdominant. The work provides a fast, flexible tool for precise fiducial cross sections and multi-differential observables, with future plans to include top decays and EW corrections and to release the code publicly.

Abstract

We report on a new fully differential calculation of the next-to-next-to-leading-order (NNLO) QCD radiative corrections to the production of top-quark pairs at hadron colliders. The calculation is performed by using the $q_T$ subtraction formalism to handle and cancel infrared singularities in real and virtual contributions. The computation is implemented in the Matrix framework, thereby allowing us to efficiently compute arbitrary infrared-safe observables for stable top quarks. We present NNLO predictions for several single- and double-differential kinematical distributions in $pp$ collisions at the centre-of-mass energy $\sqrt{s}=13$ TeV, and we compare them with recent LHC data by the CMS collaboration.

Figures (9)

• Figure 1: Single-differential cross sections as a function of $p_{T,t_\text{high}}$. CMS data Sirunyan:2018wem and LO, NLO and NNLO results for central scales equal to $H_{T}/2$ (left), $m_{T,t_\text{high}}$ (central) and $m_{T,t_\text{high}}/2$ (right).
• Figure 2: Single-differential cross sections as a function of $p_{T,t_\text{low}}$. CMS data Sirunyan:2018wem and LO, NLO and NNLO results for central scales equal to $H_{T}/2$ (left), $m_{T,t_\text{low}}$ (central) and $m_{T,t_\text{low}}/2$ (right).
• Figure 3: Single-differential cross sections as a function of $p_{T,t_\text{had}}$. CMS data Sirunyan:2018wem and LO, NLO and NNLO results for central scales equal to $H_{T}/2$ (left), $m_{T,t_{\rm av}}$ (central) and $m_{T,t_{\rm av}}/2$ (right).
• Figure 4: Single-differential cross sections as a function of $m_{t{\bar{t}}}$. CMS data Sirunyan:2018wem and LO, NLO and NNLO results for central scales equal to $H_{T}/2$ (left), $m_{t{\bar{t}}}/2$ (central) and $H_{T}/4$ (right).
• Figure 5: Single-differential cross sections as a function of $y_{t{\bar{t}}}$. CMS data Sirunyan:2018wem and LO, NLO and NNLO results for central scales equal to $H_{T}/2$ (left), ${m_{t}}$ (central) and $H_{T}/4$ (right).