Heavy flavour production
Precision predictions for heavy flavour production
The production of massive quarks (charm and bottom quarks) in high-energy collisions is an essential probe of Standard Model physics, particularly Quantum Chromodynamics. These quarks typically form bound states, i.e. heavy hadrons (D and B mesons, or Lambda-Baryons, for example), with a comparatively long lifetime before they decay via the weak interaction to lighter states. This property gives them a unique experimental signature in the form of displaced vertices, as these particles live long enough to travel macroscopic distances in the detectors. Therefore, heavy quarks/hadrons are essential for experimentally identifying specific final-state particles, such as top-quarks (which predominantly decay into b-quarks) and Higgs bosons or associated production with an electroweak boson.
The theoretical descriptions of such processes face various (technical) challenges depending on the energy regime under consideration. Heavy flavour quarks are typically studied at high energy scales in association with other heavy particles, such as electroweak bosons, or after top-quark pair production. The direct QCD production of bottom/charm quarks is more relevant at low energies.
If heavy-flavour quarks are produced in association with particles such as electroweak bosons, they typically have high transverse momentum. This energy is radiated as a spray of particles before the bound state formation begins and forms a jet. For many phenomenological applications, measuring the properties of this heavy-flavour jet is more beneficial than the individual reconstructed hadrons, as these jets can be better calibrated and are in closer correspondence to the 'hard-scattering' process. Higher-order QCD corrections are of substantial importance to describe these processes accurately. Treating the mass of the quarks comes, however, with technical difficulties; first, as these masses are much smaller than the transverse momentum, they lead to potentially large logarithms spoiling the stability of the predictions if not resumed, and second, keeping the mass in loop calculations makes these considerably harder to perform. Therefore, treating the heavy flavour jets in massless QCD can be particularly advantageous for purely perturbative calculations. However, this comes at the cost of the need for so-called flavoured-jet algorithms specially designed to avoid subtle infra-red safety issues when working with massless quarks. A crucial aspect of my work on heavy-flavour jets is to develop the flavour-anti-kT, or CMP, jet algorithm and apply it to LHC phenomenology.
The transverse momenta are typically small in the QCD production of bottom/charm quark pairs (open-bottom/open-charm). In this regime, it is crucial to consider the effects of the quark masses and the non-perturbative effects describing the hadron formation.
Related publications
2024
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Measurement of the production cross section for a W boson in association with a charm quark in proton–proton collisions at \sqrts = 13\,\hbox TeVEur. Phys. J. C 84 27, 2024Arxiv:2308.02285
2022
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Precision comparisons between theory and data in t\bart-production at the LHCIn 15th International Workshop on Top Quark Physics , Dec 2022Arxiv:2212.06019
2023
2023
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NNLO B-fragmentation fits and their application to t\overlinet production and decay at the LHCJHEP 03 251, 2023Arxiv:2210.06078
2022
2023
2022
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Next-to-next-to-leading order QCD corrections to Wbb\textasciimacron production at the LHCPhys. Rev. D 106 7 074016, 2022Arxiv:2205.01687
2022
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W+c-jet production at the LHC with NNLO QCD accuracySciPost Phys. Proc. 7 035, 2022Arxiv:2110.05104