Multi-jet merged top-pair production including electroweak corrections

TL;DR

This paper provides advanced theoretical predictions for top-quark pair production with jets at the LHC, including electroweak corrections, and demonstrates improved agreement with experimental data.

Contribution

It introduces a method to incorporate electroweak corrections into multi-jet merged predictions for top-pair production, enhancing modeling accuracy.

Findings

Electroweak corrections significantly affect top transverse momentum distributions.

The proposed approximation of EW corrections is accurate at the percent level.

Predictions with EW corrections show excellent agreement with ATLAS data.

Abstract

We present theoretical predictions for the production of top-quark pairs in association with jets at the LHC including electroweak (EW) corrections. First, we present and compare differential predictions at the fixed-order level for $t \bar t$ and $t \bar t+$jet production at the LHC considering the dominant NLO EW corrections of order $\mathcal{O}(\alpha_S^2 \alpha)$ and $\mathcal{O}(\alpha_S^3 \alpha)$ respectively together with all additional subleading Born and one-loop contributions. The NLO EW corrections are enhanced at large energies and in particular alter the shape of the top transverse momentum distribution, whose reliable modelling is crucial for many searches for new physics at the energy frontier. Based on the fixed-order results we motivate an approximation of the EW corrections valid at the percent level, that allows us to readily incorporate the EW corrections in the MEPS@NLO framework of Sherpa combined with OpenLoops. Subsequently, we present multi-jet merged parton-level predictions for inclusive top-pair production incorporating NLO QCD+EW corrections to $t \bar t$ and $t \bar t+$jet. Finally, we compare at the particle-level against a recent 8 TeV measurement of the top transverse momentum distribution performed by ATLAS in the lepton+jet channel. We find very good agreement between the Monte Carlo prediction and the data when the EW corrections are included.