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Measurements of top quark asymmetries

Nils Faltermann

TL;DR

Top quark asymmetries at the LHC offer a precision probe of SM higher-order QCD and EFT effects, leveraging cancellations of systematics in asymmetry observables. The paper aggregates the latest ATLAS and CMS measurements across inclusive ttbar production, ttbar associated with vector bosons, and ttbar plus jet, including differential and leptonic final states. The results broadly agree with SM predictions, with no strong evidence for new physics, though several jet-associated asymmetries show mild tensions in specific bins that warrant more data. Overall, these observables validate SM expectations and set constraints on EFT scenarios, while highlighting the continued potential for future measurements as lumi increases.

Abstract

The study of top quark asymmetries at the LHC provides an excellent opportunity to probe subtle differences in the production of top quarks and antiquarks made by the standard model of particle physics. In this contribution, the latest experimental results on this topic by the ATLAS and CMS Collaborations are summarized.

Measurements of top quark asymmetries

TL;DR

Top quark asymmetries at the LHC offer a precision probe of SM higher-order QCD and EFT effects, leveraging cancellations of systematics in asymmetry observables. The paper aggregates the latest ATLAS and CMS measurements across inclusive ttbar production, ttbar associated with vector bosons, and ttbar plus jet, including differential and leptonic final states. The results broadly agree with SM predictions, with no strong evidence for new physics, though several jet-associated asymmetries show mild tensions in specific bins that warrant more data. Overall, these observables validate SM expectations and set constraints on EFT scenarios, while highlighting the continued potential for future measurements as lumi increases.

Abstract

The study of top quark asymmetries at the LHC provides an excellent opportunity to probe subtle differences in the production of top quarks and antiquarks made by the standard model of particle physics. In this contribution, the latest experimental results on this topic by the ATLAS and CMS Collaborations are summarized.
Paper Structure (5 sections, 4 equations, 4 figures)

This paper contains 5 sections, 4 equations, 4 figures.

Table of Contents

  1. Introduction
  2. Asymmetry in top quark pair production
  3. Top quark pair production in association with vector bosons
  4. Energy and incline asymmetry in top quark pair plus jet production
  5. Summary

Figures (4)

  • Figure 1: Results of the differential measurement of the top quark charge asymmetry from the ATLAS (left) and CMS (right) Collaborations ATLAS:2022waaCMS:2022ged.
  • Figure 2: Results for the top quark charge asymmetry in $\mathrm{t}\overline{\mathrm{t}}\gamma$ production by the ATLAS (left) and CMS (right) experiments ATLAS:2022wecCMS:2025oki.
  • Figure 3: Lepton charge asymmetry results obtained by the ATLAS ATLAS:2023xay (left) and CMS CMS:2025iwa (right) Collaborations in associated $\mathrm{t}\overline{\mathrm{t}}\mathrm{W}$ production.
  • Figure 4: Exemplary results for the energy asymmetry in $\mathrm{t}\overline{\mathrm{t}} j$ production by the ATLAS Collaboration ATLAS:2021dqb (left) and for the incline asymmetry by the CMS Collaboration CMS:2025qmd (right).