Dimensional reduction of the Standard Model coupled to a new singlet scalar field

Understand

We derive an effective dimensionally reduced theory for the Standard Model augmented by a real singlet scalar.

• We treat the singlet as a superheavy field and integrate it out, leaving an effective theory involving only the Higgs and $\mathrm{SU}(2)_\mathrm{L} \times \mathrm{U}(1)_Y$ gauge fields, identical to the one studied previously for the Standard Model.
• This opens up the possibility of efficiently computing the order and strength of the electroweak phase transition, numerically and nonperturbatively, in this extension of the Standard Model.
• Understanding the phase diagram is crucial for models of electroweak baryogenesis and for studying the production of gravitational waves at thermal phase transitions.