Dark matter and electroweak phase transition in the Z2 symmetric Georgi-Machacek model

A bstract We present a comprehensive investigation of the Z 2 symmetric Georgi-Machacek (GM) model, focusing on the dark matter (DM) in the model and the electroweak phase transition (EWPT). Our analysis encompasses multiple detections for the DM candidates, including collider searches at the LHC and LEP, the direct detection and indirect detection. Furthermore, we also explore the possibility of a first-order EWPT in this framework. The gravitational wave (GW) generated from the first-order EWPT also provides a detection method for the parameter space in the Z 2 symmetric GM model providing viable DM candidate. It is found that the current DM searches, especially the direct detection, provide strong constraints on the parameter space. Among the parameter space that can provide observed DM relic density, only the region around the Higgs resonance can satisfy the current constraints. However, with even higher mass, much lager parameter space exists providing sub-dominant DM relic density. On the other hand, the complementarity of gravitational-wave detection with other experimental searches is especially pronounced near the Higgs resonance, a key benchmark for integrated analysis.