RESUMO
The trilinear Higgs coupling λ_{hhh} is crucial for determining the structure of the Higgs potential and for probing possible effects of physics beyond the standard model. Focusing on the two-Higgs-doublet model as a concrete example, we identify parameter regions in which λ_{hhh} is significantly enhanced with respect to the standard model. Taking into account all relevant corrections up to the two-loop level, we show that already current experimental bounds on λ_{hhh} rule out significant parts of the parameter space that would otherwise be unconstrained. We illustrate the interpretation of the results on λ_{hhh} for a benchmark scenario. Similar results are expected for wide classes of models with extended Higgs sectors.
RESUMO
The calculation of the Higgs mass in general renormalisable field theories has been plagued by the so-called "Goldstone Boson Catastrophe," where light (would-be) Goldstone bosons give infra-red divergent loop integrals. In supersymmetric models, previous approaches included a workaround that ameliorated the problem for most, but not all, parameter space regions; while giving divergent results everywhere for non-supersymmetric models! We present an implementation of a general solution to the problem in the public code SARAH, along with new calculations of some necessary loop integrals and generic expressions. We discuss the validation of our code in the Standard Model, where we find remarkable agreement with the known results. We then show new applications in Split SUSY, the NMSSM, the Two-Higgs-Doublet Model, and the Georgi-Machacek model. In particular, we take some first steps to exploring where the habit of using tree-level mass relations in non-supersymmetric models breaks down, and show that the loop corrections usually become very large well before naive perturbativity bounds are reached.