Scalar dark matter in the conformally invariant extension of the standard model

Dong-Won Jung,Jungil Lee,Soo-Hyeon Nam

doi:10.1016/j.physletb.2019.134823

Abstract

We study a classically scale-invariant model with an electroweak singlet scalar mediator together with a scalar dark matter multiplet of global O(N) symmetry. Our most general conformally invariant scalar potential generates the electroweak symmetry breaking via the Coleman-Weinberg mechanism, and the new scalar singlet acquires its mass through radiative corrections of the SM particles and the scalar dark matter. Taking into account the collider bounds, we present the allowed region of new physics parameters satisfying the recent measurement of relic abundance. With the obtained parameter sets, we predict the elastic scattering cross section of the new scalar multiplet into target nuclei for a direct detection of the dark matter. We also perform a full analysis with arbitrary set of parameters for N≥2, and discuss the implication of the constraints from the on-going direct and indirect detections of dark matter.

Highlights

Since the discovery of the Higgs boson at the Large Hadron Collider (LHC) [1, 2], the Standard Model (SM) has been remaining quite successful in spite of many experimental pursuits of physics beyond the SM (BSM)
The SM Higgs h1 and the dark matter (DM) scalars φ have the tree-level masses while the new scalar singlet h2 acquires its mass through radiative corrections, which is similar to the cases considered in Refs. [52, 67]
The model extends the Higgs sector to have an additional electroweak singlet scalar mediator, scalon, together with a scalar multiplet of global O(N ) symmetry, and the electroweak symmetry is broken via the CW mechanism

Summary

INTRODUCTION

Since the discovery of the Higgs boson at the Large Hadron Collider (LHC) [1, 2], the Standard Model (SM) has been remaining quite successful in spite of many experimental pursuits of physics beyond the SM (BSM). With the most general conformally invariant Lagrangian, we employ the framework of Gildener-Weinberg (GW) [84], where a flat direction at tree-level is lifted by radiative corrections. In this way, the vacuum structure is determined and a light pseudo Nambu-Goldstone boson, called ‘scalon’, appears as a result of conformal symmetry breaking. The SM Higgs h1 and the DM scalars φ have the tree-level masses while the new scalar singlet h2 acquires its mass through radiative corrections, which is similar to the cases considered in Refs. Even if the radiatively generated h2 mass is less than a half of the h1 mass, the partial decay width Γ (h1 → h2h2) is negligible and our model is not constrained by the invisible Higgs decay measurements

EFFECTIVE POTENTIAL

RESULTS

SUMMARY AND CONCLUSION