A Comprehensive Analysis of the R2HDM Vacuum Evolution and the Induced GW and Collider Phenomenology

Abstract: Extended Higgs sectors beyond the Standard Model (BSM) allow to dynamically generate the observed baryon asymmetry of the Universe through electroweak baryogenesis and thereby solve one of the most prominent open problems of the SM. The strong first-order phase transitions (PTs), required to preserve the generated asymmetry in the electroweak vacuum, source gravitational waves (GW) that can be tested at future experiments like LISA. Gravitational waves hence provide the exciting possibility to probe BSM physics through cosmological processes. In order to be able to eventually pin down the specific underlying physics, a good understanding of the evolution of the vacuum of the model under investigation is indispensable as well as of the uncertainties that are involved in the derivation of the GW spectrum. We use our code BSMPTv3 that allows to reliably derive the finite temperature vacuum structure of extended Higgs sectors with multiple vacuum directions and calculates the GW spectrum of the found (multiple) strong first-order PTs, and we apply it to the real, i.e. CP-conserving, 2-Higgs-Doublet Model. Taking into account all relevant theoretical and experimental constraints, we perform a thorough analysis of its vacuum evolution, the related collider and GW phenomenology and complement it by an uncertainty discussion.