Next-to-leading order QCD corrections to t-tbar-Z production at the LHC

TL;DR

This paper calculates the full next-to-leading order QCD corrections to the pp → t tbar Z process at the LHC, improving the precision of electroweak coupling measurements and introducing a novel numerical approach.

Contribution

It provides the first complete NLO QCD correction calculation for the t tbar Z production process using a new numerical method.

Findings

QCD corrections increase the leading order result by 35%.

Theoretical uncertainty is reduced to about 10%.

Results aid in precise measurement of electroweak couplings.

Abstract

We present a calculation of the full next-to-leading order QCD corrections to the scattering process pp \to t tbar Z. This channel will be used to measure the t tbar Z electroweak couplings at the Large Hadron Collider. These couplings cannot be directly measured in current experiments. To obtain these results, we utilize a novel, completely numerical approach to performing higher order QCD calculations. We find that for reasonable values of the renormalization and factorization scales the QCD corrections increase the leading order result by 35 percent, while reducing the theoretical error arising from uncalculated higher order corrections to approximately 10 percent.