# The top quark charge asymmetry in $t\bar{t}\gamma$ production at the LHC

## TL;DR

This paper analyzes the top quark charge asymmetry in $tar{t}+ ext{photon}$ production at the 13 TeV LHC, examining theoretical predictions and experimental prospects for observing the asymmetry amidst various effects.

## Contribution

It provides a next-to-leading order QCD analysis of the top quark charge asymmetry in $tar{t}+ ext{photon}$ production and explores strategies to enhance and measure this asymmetry.

## Key findings

- Genuine asymmetry in $qar{q}$ channel is about -12%.
- Higher order corrections significantly affect the asymmetry.
- Dedicated cuts can improve the observability of the asymmetry.

## Abstract

We consider the top quark charge asymmetry in the process $pp \to t\bar{t}+\gamma$ at the 13 TeV LHC. The genuine tree level asymmetry in the $q\bar{q}$ channel is large with about -12%. However, the symmetric $gg$ channel, photon radiation off top quark decay products, and higher order corrections wash out the asymmetry and obscure its observability. In this work, we investigate these effects at next-to-leading order QCD and check the robustness of theoretical predictions. We find a sizable perturbative correction and discuss its origins and implications. We also study dedicated cuts for enhancing the asymmetry and show that a measurement is possible with an integrated luminosity of 150 fb$^{-1}$.