HET-Discovery seminar by Ken Mimasu – University of Copenhagen

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HET-Discovery seminar by Ken Mimasu

Title: The hierarchical two-Higgs-doublet model: probing the electroweak phase transition at the LHC

Abstract: I motivate the two-Higgs-doublet model (2HDM) as a candidate for the realisation of a strongly first order electroweak (EW) phase transition in the early universe, paving the way towards successful EW baryogenesis. A detailed study of the viable parameter space points to an interesting and oft-overlooked scenario in which significant mass splittings occur between the new scalars i.e. a 'hierarchical 2HDM’. I discuss the ‘smoking-gun’ signature of a pseudoscalar decaying to a heavy Higgs and Z boson that is favoured by the requirement of a strongly first order EW phase transition. Finally I present a  review of the experimental status of general hierarchical 2HDM scenarios after LHC run 1, showing that the picture of constraints is dramatically changed with respect to the degenerate case, and look ahead to LHC run 2.