Modelling of top quark decays in $t\bar{t}\gamma$ production at the LHC

TL;DR

This paper presents a state-of-the-art NLO QCD calculation for top quark pair production with an associated photon at the LHC, including off-shell effects and interference, providing detailed cross section predictions.

Contribution

It introduces a comprehensive NLO QCD computation for $tar{t}\gamma$ production at the LHC, incorporating off-shell and interference effects at the matrix element level.

Findings

NLO QCD corrections significantly affect cross section predictions.

Off-shell and interference effects are crucial for accurate modeling.

Comparison with narrow-width approximation highlights modeling differences.

Abstract

In this proceedings we briefly report on the state-of-the-art NLO QCD computation for the $pp\to t\bar{t}\gamma$ process in the di-lepton channel. We describe higher-order corrections to the $e^+\nu_e \, \mu^- \bar{\nu}_\mu \, b\bar{b}\gamma$ final state at the LHC with $\sqrt{s}=13$ TeV. Off-shell top quarks, double-, single- as well as non-resonant top-quark contributions along with all interference effects are consistently incorporated at the matrix element level. Results are presented in the form of fiducial integrated and differential cross sections. The impact of top quark modelling is scrutinised by an explicit comparison with the results in the narrow-width approximation. Both types of predictions are now available in the HELAC-NLO framework.