LHC Phenomenology of an Extended Standard Model with a Real Scalar Singlet

TL;DR

This paper explores how extending the Standard Model with a real scalar singlet affects Higgs physics and dark matter, analyzing collider constraints, relic density, and detection prospects.

Contribution

It provides a comprehensive analysis of a minimal singlet extension, covering Higgs phenomenology, dark matter viability, and experimental signatures at the LHC.

Findings

Constraints on Higgs mixing from electroweak precision tests

Conditions for singlet dark matter to match relic density

Predicted collider signatures and direct detection cross sections

Abstract

Gauge singlet extensions of the Standard Model (SM) scalar sector may help remedy its theoretical and phenomenological shortcomings while solving outstanding problems in cosmology. Depending on the symmetries of the scalar potential, such extensions may provide a viable candidate for the observed relic density of cold dark matter or a strong first order electroweak phase transition needed for electroweak baryogenesis. Using the simplest extension of the SM scalar sector with one real singlet field, we analyze the generic implications of a singlet-extended scalar sector for Higgs boson phenomenology at the Large Hadron Collider (LHC). We consider two broad scenarios: one in which the neutral SM Higgs and singlet mix and the other in which no mixing occurs and the singlet can be a dark matter particle. For the first scenario, we analyze constraints from electroweak precision observables and their implications for LHC Higgs phenomenology. For models in which the singlet is stable, we determine the conditions under which it can yield the observed relic density, compute the cross sections for direct detection in recoil experiments, and discuss the corresponding signatures at the LHC.