Discovering Heavy Neutral Leptons with the Higgs Boson

Abstract: We study the dominant signatures that arise in Higgs physics at colliders when extending the Standard Model (SM) with a Yukawa interaction to heavy neutral leptons (HNL), while suppressing their mixing to active neutrinos. We focus on the production of HNLs from Higgs bosons that subsequently decay via the Higgs to SM fermions to determine the experimental reach at the LHC detectors and far detectors such as FASER and MATHUSLA. We also determine the impact of precision Higgs constraints on beyond-SM parameters in this scenario.