Precision calculations for loop-induced Higgs-boson production and decay processes

• Applicant: Dr. Christian Sturm
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2020 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 436076086

One of the most important achievements of particle physics in the last decade was the discovery of a Higgs boson at the Large Hadron Collider(LHC) experiments. This new particle is now central object of intense investigations, both in theory and experiment, in order to precisely determine its properties. In particular, it is interesting to understand whether this Higgs boson is just the Standard Model(SM) Higgs boson or whether it is part of a more general theory. In order to give answers to this question precise theory predictions are necessary, both within the SM as well as within extensions of the SM. These precise theory predictions are addressed in this project.Loop-induced processes play a special key role in the context of Higgs physics. Since the Higgs boson only couples to massive particles, Higgs-boson production and decay processes which involve massless particles in the initial or final state, like gluons or photons, proceed via a massive particle loop. These loop-induced processes are important on the one hand since they contributed substantially to the discovery of a Higgs-boson at the LHC, on the other hand they are sensitive to new physics beyond the SM.One of the simplest extensions of the Higgs sector of the SM is the one with an extra spin-zero gauge singlet added to the SM fieldcontent. This model has a rich collider phenomenology which can be tested at the LHC. This model can also give answers to still open questions, which remain unanswered within the SM, like for example, the question of the nature of dark matter or the question of the origin of the matter-antimatter asymmetry of the Universe. Within this project the impact of electroweak correction in perturbation theory to loop-induced processes shall be analyzed. Since the leading-order process for loop-induced processes is already at the one-loop level, the computation of next-to-leading order corrections involves here already the computation of challenging two-loop diagrams.

• DFG Programme: Research Grants