Automated EW corrections with isolated photons: $t \bar t \gamma$, $t \bar t \gamma\gamma$ and $t \gamma j$ as case studies

TL;DR

This paper presents the first automated Complete-NLO predictions for top-quark pair production with isolated photons, extending computational tools to include electroweak corrections for these processes.

Contribution

It introduces an automated approach within MadGraph5_aMC@NLO for calculating Complete-NLO predictions involving isolated photons in top-quark processes, including technical implementation details.

Findings

First Complete-NLO predictions for $t\bar{t}\gamma$ production.

NLO QCD+EW predictions for $t\bar{t}\gamma\gamma$ and single-top with photons.

Extension of MadGraph5_aMC@NLO capabilities to processes with isolated photons.

Abstract

In this work we compute for the first time the so-called Complete-NLO predictions for top-quark pair hadroproduction in association with at least one isolated photon ($ t \bar t \gamma$). We also compute NLO QCD+EW predictions for the similar case with at least two isolated photons ($ t \bar t \gamma\gamma$) and for single-top hadroproduction in association with at least one isolated photon. In addition, we complement our results with NLO QCD+EW predictions of the hadronic and leptonic decays of top-quark including an isolated photon. All these results have been obtained in a completely automated approach, by extending the capabilities of the MadGraph5_aMC@NLO framework and enabling the Complete-NLO predictions for processes with isolated photons in the final state. We discuss the technical details of the implementation, which involves a mixed EW renormalisation scheme for such processes.