Higgs partner searches and dark matter phynomenology in a classically scale invariant Higgs boson sector

Abstract

In a previous work, a classically scale invariant extension of the standard model was proposed, as a potential candidate for resolving the hierarchy problem, by minimally introducing a complex gauge singlet scalar and generating radiative electroweak symmetry breaking by means of the Coleman- Weinberg mechanism. Postulating the singlet sector to respect the CP symmetry, the existence of a stable pseudoscalar dark matter candidate with a mass in the TeV range was demonstrated. Moreover, the model predicted the presence of another physical CP-even Higgs boson (with suppressed tree-level couplings), in addition to the 125 GeV scalar discovered by the LHC. The viable region of the parameter space was determined by various theoretical and experimental considerations. In this work, we continue to examine the phenomenological implications of the proposed minimal scenario by considering the constraints from the dark matter relic density, as determined by the Planck Collaboration, as well as the direct detection bounds from the LUX experiment. Furthermore, we investigate the implications of the collider Higgs searches for the additional Higgs boson. Our results are comprehensively demonstrated in unified exclusion plots, which analyze the viable region of the parameter space from all relevant angles, demonstrating the testability of the proposed scenario.