Natural Electroweak Symmetry Breaking from Scale Invariant Higgs Mechanism

TL;DR

This paper proposes a minimal extension of the Standard Model with scale invariance, introducing new Higgs and dark matter candidates, and demonstrates its consistency with experimental constraints while addressing the hierarchy problem.

Contribution

It presents a novel scale-invariant Higgs mechanism model that naturally explains electroweak symmetry breaking and predicts new particles relevant for dark matter.

Findings

Predicts a new CP-even Higgs as a pseudo-Nambu-Goldstone boson

Identifies a CP-odd scalar as a dark matter candidate

Shows viable parameter space consistent with current experimental constraints

Abstract

We construct a minimal viable extension of the standard model (SM) with classical scale symmetry. Its scalar sector contains a complex singlet in addition to the SM Higgs doublet. The scale-invariant and CP-symmetric Higgs potential generates radiative electroweak symmetry breaking a la Coleman-Weinberg, and gives a natural solution to the hierarchy problem, free from fine-tuning. Besides the 125GeV SM-like Higgs particle, it predicts a new CP-even Higgs (serving as the pseudo-Nambu-Goldstone boson of scale symmetry breaking) and a CP-odd scalar singlet (providing the dark matter candidate) at weak scale. We systematically analyze experimental constraints from direct LHC Higgs searches and electroweak precision tests, as well as theoretical bounds from unitarity, triviality and vacuum stability. We demonstrate the viable parameter space, and discuss implications for new Higgs and dark matter (DM) searches at the upcoming LHC runs and for the on-going direct detections of DM.