Strongly first-order electroweak phase transition by relatively heavy additional Higgs bosons

We discuss first-order electroweak phase transition in models with extended Higgs sectors for the case relatively heavy additional scalar bosons. first show that, by combination of sphaleron decoupling condition, perturbative unitarity and vacuum stability, mass upper bounds on bosons can be obtained at TeV scale even alignment limit where lightest boson behaves exactly like SM tree level. then phenomenological impacts near 1 TeV. Even when they are too to directly detected current future experiments hadron colliders, large deviation triple coupling a signature due quantum effects such On other hand, gravitational waves from found weaker this as compared that lower masses