Two Higgs doublets, effective interactions and a strong first-order electroweak phase transition

Abstract

It is well-known that type II two Higgs doublet models (2HDMs) can struggle to facilitate a strong first-order electroweak phase transition in the early universe whilst remaining theoretically appealing scenarios for many reasons. We analyse this apparent shortfall from the perspective of additional new physics. Starting from a consistent dimension-6 effective field theory Higgs potential extension, we identify the Higgs potential extensions that provide the necessary additional contributions required to achieve a strong first-order electroweak phase transition and trace their phenomenological implications for the Large Hadron Collider. In passing, we critically assess the reliability of the dimension-6 approximation depending on the expected 2HDM phenomenology. In particular, we focus on the role of Higgs pair production (resonant and non-resonant) and interference effects expected in top final states, which are the prime candidates of 2HDM exotics discoveries.

MUonE, muon $g-2$ and electroweak precision constraints within 2HDMs

“…Particularly interesting in this context is the two Higgs doublet model, which continues to have appealing phenomenological properties with regards to the UV completion of the SM [22][23][24][25][26][27][28][29][30][31][32][33][34]. For Z 2 symmetry assignments of the two Higgs doublet models (2HDMs) that avoid treelevel neutral current flavour violation [35], we will show that there are parameter regions that can explain the a µ anomaly whilst avoiding Large Electron Positron (LEP), LHC and flavour constraints (see also [31,33,36]).…”