Controlling the fine-tuning problem with singlet scalar dark matter

Understand

Assuming that no other conventional new physics is found immediately at the LHC, we investigate how just the consistent solution of the scalar mass hierarchy problem points towards the minimal necessary field content.

• We show that to ameliorate the fine-tuning problem, one needs to introduce more scalar degrees of freedom.
• The simplest solution is one or more real singlets (with the possibility of combining two of them in a complex singlet), which may act as viable cold dark matter candidates, because the constraints on the scalar potential disfavor any mixing between the new scalar(s) with the SM doublet.
• Furthermore, the fine-tuning problem of the new scalars necessitates the introduction of vector-like fermions.