Two Higgs doublets, effective interactions and a strong first-order electroweak phase transition
Anisha (Department of Physics, Indian Institute of Technology, Kanpur, 208016, India, School of Physics & Astronomy, University of Glasgow, Glasgow, G12 8QQ, U.K.); Lisa Biermann (Institute for Theoretical Physics, Karlsruhe Institute of Technology, Karlsruhe, 76128, Germany); Christoph Englert (School of Physics & Astronomy, University of Glasgow, Glasgow, G12 8QQ, U.K.); Margarete Mühlleitner (Institute for Theoretical Physics, Karlsruhe Institute of Technology, Karlsruhe, 76128, Germany)
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.
