Two-loop stability of a complex singlet extended Standard Model

TL;DR

This paper investigates the stability and phenomenology of a complex singlet extension of the Standard Model, incorporating two-loop calculations, experimental constraints, and implications for dark matter and scalar masses.

Contribution

It provides a detailed two-loop renormalization group analysis of the model's stability and derives new bounds on scalar and dark matter particle masses considering experimental data.

Findings

Scalar mixing mass must be >140 GeV for stability.

Dark matter particle must be heavier than 50 GeV.

Stability up to the GUT scale requires scalar mass >170 GeV.

Abstract

Motivated by the dark matter and the baryon asymmetry problems, we analyse a complex singlet extension of the Standard Model (SM) with a Z2 symmetry (which provides a dark matter candidate). After a detailed two-loop calculation of the renormalization group equations for the new scalar sector, we study the radiative stability of the model up to a high energy scale (with the constraint that the 126 GeV Higgs boson found at the LHC is in the spectrum) and find it requires the existence of a new scalar state mixing with the Higgs with a mass larger than 140 GeV. This bound is not very sensitive to the cut-off scale as long as the latter is larger than 10^10 GeV. We then include all experimental and observational constraints/measurements from collider data, dark matter direct detection experiments and from the Planck satellite and in addition force stability at least up to the GUT scale, to find that the lower bound is raised to about 170 GeV, while the dark matter particle must be heavier than about 50 GeV.