An EFT approach to the study of multi-phase criticality scenarios

Abstract: Multi-phase critical scenarios explain the observed Higgs boson mass scale by the almost simultaneous occurrence of two smoothly connected phases of the theory, which differ by the selected vacuum configuration. A generic prediction of the framework is the presence of a further light scalar state, the dilaton, which naturally couples weakly to the Higgs boson. The implementation of the framework usually requires the presence of a third, heavier state, which plays the role of dark matter and ensures the couplings run so that the multi-phase criticality condition is met. In this paper we consider the multi-phase criticality limit of an extension of the Standard Model including two extra scalar singlets, addressing the scenario with effective field theory methods that are particularly suited for treating the hierarchical mass spectrum that this construction yields. The analysis improves on the approximated results available in the Literature and explores the phenomenology of the model at collider and dark matter experiments. We find that the running of scalar couplings in the EFT between the two scales cannot be ignored, but the quantum corrections from the dark matter candidate are not noticeably modified.