%0 Thesis
%A Rogner, Victor
%T On Higher-Order Contributions to the Trilinear Higgs Self-Coupling in the SM and Beyond
%I University of Hamburg
%V Masterarbeit
%M PUBDB-2025-02532
%P 83
%D 2025
%Z Masterarbeit, University of Hamburg, 2025
%X We present a precision computation of the trilinear Higgs boson self-coupling λ<sub>hhh</sub> in the Standard Model (SM) and the Type-II Two-Higgs-Doublet-Model () in the alignment limit, both with vanishing external momenta for the vertex, employing a fully on-shell renormalization scheme. Our analysis includes all one-loop corrections and, for the first time to our knowledge, the dominant two-loop top- and bottom-Yukawa contributions of <i>O</i>(N<sub>c</sub><sup>2</sup>). Analytic results consisting of the leading contributions for a heavy top quark are also derived.We evaluate the results in both the α- and G<sub>F</sub>-parametrizations. In the SM, λ<sub>hhh</sub> is reduced from its tree-level value of 187.3 GeV (α) and 190.7 GeV (G<sub>F</sub>) to 175.479 GeV and 175.715 GeV, respectively, when including the full one-loop and the two-loop top- and bottom-Yukawa corrections of <i>O</i>(N<sub>c</sub><sup>2</sup>).In the , the phenomenologically viable parameter space is investigated. In the alignment limit, heavy scalar masses in the 600-1000 GeV range can enhance λ<sub>hhh</sub> substantially, with values up to  ∼ 980 GeV being consistent with current constraints.We further analyze the sensitivity of λ<sub>hhh</sub> to beyond-the-Standard-Model (BSM) effects by parametrizing deviations with respect to the one-loop contributions in the Standard Model. The current experimental bounds κ<sub>λ</sub>  ∈ [−1, 7] allow sizeable modifications to the trilinear Higgs coupling, which is investigated with respect to the new two-loop contributions in the Standard Model.
%F PUB:(DE-HGF)19
%9 Master Thesis
%U https://bib-pubdb1.desy.de/record/634618