Top-quark pair production and decay

Higher-order corrections to top-quark production and their decays

NNLO QCD corrections to top-quark pair production and decay

Since their discovery in high energy collisions at the Tevatron collider more than twenty years ago, top quarks constitute an essential pillar of modern particle physics. As the heaviest particles of the Standard Model of particle physics (SM), they are crucial in many phenomenological applications. Their large mass relates them tightly to various other components of the SM. Examples of importance are parameters of the electroweak sector, which are influenced by corrections originating from top-quark loops. This property enables essential consistency checks of the SM itself. For such checks, precisely known parameters estimated from measurements at colliders like the LHC are crucial. By carefully comparing data and theoretical predictions, parameters of the theory, e.g. the top-quark mass, can be extracted.

To do so, accurate predictions in perturbation theory are necessary. Quantum Chromo Dynamics (QCD) describe the strong interaction between coloured particles and most of the dynamics of top quarks produced in high energy collisions of hadronic bound states. State-of-the-art calculations evaluate the partonic cross section at next-to-next-to-leading order (NNLO). Thus, perturbative QCD is used to obtain predictions of fully inclusive or differential cross sections of top quarks, which show excellent agreement with the measurements, while minor uncertainties on the theoretical and experimental side allow for precise parameter extractions. These measurements rely on well-understood modelling of the top quarks in hard scattering processes.

A remarkable feature of top quarks is their short lifetime, below even the typical hadronisation time of coloured particles. Top-quark decays thus present a unique opportunity for studying a bare quark. The central goal of this work is to include the decay in the evaluation of top-quark pair production through NNLO in QCD. The narrow-width approximation (NWA) reduces the computational burden by factorising production and decay. It is possible to keep information about the polarisation state of the top quarks, which affects the decay through the computation of polarised amplitudes.

Related publications

2022

  1. Precision comparisons between theory and data in t\bart-production at the LHC
    Rene Poncelet
    In 15th International Workshop on Top Quark Physics , Dec 2022
    Arxiv:2212.06019

2023

  1. NNLO B-fragmentation fits and their application to t\overlinet production and decay at the LHC
    Michał Czakon ,  Terry Generet ,  Alexander Mitov ,  and  Rene Poncelet
    JHEP 03 251, 2023
    Arxiv:2210.06078

2021

  1. B-hadron production in NNLO QCD: application to LHC t \overlinet events with leptonic decays
    Micha L. Czakon ,  Terry Generet ,  Alexander Mitov ,  and  Rene Poncelet
    JHEP 10 216, 2021
    Arxiv:2102.08267

2021

  1. NNLO QCD corrections to leptonic observables in top-quark pair production and decay
    Michal Czakon ,  Alexander Mitov ,  and  Rene Poncelet
    JHEP 05 212, 2021
    Arxiv:2008.11133

2019

  1. Higher order corrections to spin correlations in top quark pair production at the LHC
    Arnd Behring ,  Michal Czakon ,  Alexander Mitov ,  Andrew S. Papanastasiou ,  and  Rene Poncelet
    Phys. Rev. Lett. 123 8 082001, 2019
    Arxiv:1901.05407

2018

  1. Polarized double-virtual amplitudes for heavy-quark pair production
    L. Chen ,  M. Czakon ,  and  R. Poncelet
    JHEP 03 085, 2018
    Arxiv:1712.08075