Higher-order corrections for $t{\bar t}Z$ production

TL;DR

This paper calculates higher-order QCD and electroweak corrections to $t\bar{t}Z$ production, showing that soft-gluon effects are dominant, and provides improved theoretical cross sections and distributions compared to LHC data.

Contribution

It introduces approximate NNLO and N$^3$LO QCD corrections with electroweak effects for $t\bar{t}Z$ production, enhancing the precision of theoretical predictions.

Findings

Soft-gluon corrections are numerically dominant.

Approximate N$^3$LO cross sections are provided.

Theoretical results agree well with LHC measurements.

Abstract

We present calculations of higher-order QCD and electroweak (EW) corrections to the associated production of a top-antitop quark pair and a $Z$ boson, i.e. $t{\bar t}Z$ production, in proton collisions. We find that the contributions from soft-gluon corrections are numerically dominant and large. We present approximate NNLO (aNNLO) and approximate N$^3$LO (aN$^3$LO) cross sections that include soft corrections on top of the exact NLO QCD result. We also add electroweak corrections through NLO. We compare our aN$^3$LO QCD + NLO EW theoretical results to measurements of total cross sections from the LHC, and we also calculate top-quark differential distributions in transverse momentum and rapidity.