Quark mass effects in form factors and hadronic Higgs production
Nov 3, 2023Supervisors:
Thesis: PhD - ,
- RWTH Aachen University,
- RWTH Aachen U.
- Published: 2023
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Abstract: (RWTH Aachen U.)
The announcement of the experimental evidence for the Higgs boson in 2012 by the two collaborations ATLAS and CMS at the Large Hadron Collider (LHC) at CERN marks the discovery of the last missing elementary particle of the Standard Model and the continuation of the success story of the model that has so far withstood the most precise tests and whose boundaries must be pushed to the limit. The Higgs boson plays a special role in the Standard Model in the sense that it is the only particle that interacts with all massive particles and thus represents one of the most promising candidates to validate the Standard Model and to explore its limitations at the same time. In the present work we devote ourselves to the perturbative calculation of the total cross section for the production of a Higgs boson in gluon-gluon fusion at proton-proton colliders. This process is characterized by its special production mechanism, which requires a closed quark loop as a mediator between the gluons and the Higgs boson at the leading order. Although the total cross section for gluon-gluon fusion with exact quark mass dependence is known to next-to-leading order (NLO) in perturbation theory and an approximation for top quarks assumed to be infinitely heavy seems to work very well, an exact calculation retaining the full quark mass dependence is desirable. Due to the lack of knowledge of mass effects, two percent of relative uncertainty are imposed on the theoretical prediction of the total cross section. Removing this uncertainty would reduce the sum of all theoretical uncertainties by about a third. We present the most important concepts and methods indispensable for calculating the total cross section for gluon-gluon fusion to next-to-next-to-leading order (NNLO) with exact quark mass dependence. We focus on the double-virtual three-loop corrections required for the calculation and the real-virtual two-loop corrections. In order to be able to cope with the complexity of the calculation, we develop new and partly improve existing methods, whereby we mainly rely on semi-numerical methods for efficiently solving occurring integrals. Furthermore, using these methods allows us to determine three form factors at the three-loop level with exact quark mass dependence. These results constitute important tools to study the infrared behavior of scattering amplitudes and can be used to extract universal quantities.- info:eu-repo/classification/ddc/530
- Higgs boson
- LHC
- QCD
- higher-order calculations
- particle phenomenology
- quark: mass dependence
- gluon gluon: fusion
- mass: effect
- higher-order: 2
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