An extended scalar sector often emerges in models motivated by the electroweak hierarchy problem. In particular, a SM triplet is interesting because its decay is very constrained at the renormalizable level. Therefore, effective operators with a low cutoff make the triplet components decay promptly. In this talk, I will focus on the phenomenology of such triplet. I will discuss the reach of ongoing searches at the LHC, as well as projected bounds for the LHC-HL. The extended scalar sector also modifies the electroweak phase transition which can be strongly first-order and produce sizable gravitational
waves. Therefore, I will also discuss the possibility of electroweak baryogenesis in this model and constraints from gravitational waves observatories.
[Based on: epjc/s10052-019-6655-1]