Constraining the real singlet extension of the Standard Model: implications for vacuum stability

Abstract

Amongst the simplest extensions of the Standard Model is the addition of a real singlet scalar field with profound phenomenological consequences. The singlet can catalyze a strong first-order electroweak phase transition, necessary for successful electroweak baryogenesis. Furthermore, the current prediction of a metastable Higgs vacuum can be lifted towards absolute stability. While current data mainly constrain the scalar mixing angle, future measurements of the Higgs self-coupling and direct searches for additional scalar states will probe much larger parts of the viable parameter space. We report on a combined study of theoretical and experimental constraints on the real singlet extension, highlighting here in particular its implications for vacuum stability.

Comments: Contribution to the 2026 Electroweak session of the 60th Rencontres de Moriond