Minimal conformal extensions of the Higgs sector

Abstract

In this work we find the minimal extension of the Standard Model's Higgs sector which can lead to a light Higgs boson via radiative symmetry breaking and is consistent with the phenomenological requirements for a low-energy realization of a conformal theory. The model which turns out to be stable under renormalization group translations is an extension of the Standard Model by two scalar fields, one of which acquires a finite vacuum expectation value and therefore mixes into the physical Higgs. We find that the minimal model predicts a sizable amount of mixing which makes it testable at a collider. In addition to the physical Higgs, the theory's scalar spectrum contains one light and one heavy boson. The heavy scalar's properties render it a potential dark matter candidate.

The scale-invariant scotogenic model

“…Earlier works investigating SI extensions of the SM appear in refs. [66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81] and, in particular, studies of SI models for neutrino mass can be found in refs. [82][83][84][85][86][87][88][89][90][91][92].…”

Aspects of a nonminimal conformal extension of the standard model

“…Also, the possibility that neither χ nor Σ 0 acquires a nonzero vacuum expectation value is ruled out due to the appearing of Landau poles below the Planck scale [29]. Thus, we are left with the following two cases 2 :…”

“…In [29], it has already been pointed out that replacing a real gauge singlet by a higher-dimensional real SU(2) L multiplet will cause possible Landau poles to appear at higher scales, and hence we will not analyze the stability of the running coupling constants any further. Instead, we restrict our attention on other theoretical and phenomenological consequences of the model.…”

“…A recent analysis in [29] has shown that without changing the gauge sector of the SM, the minimal conformal extension of the SM that enables radiative symmetry breaking and generates no Landau poles or vacuum instabilities below the Planck scale in the renormalization-group evolution needs two real scale gauge singlets to enlarge the scalar sector of the SM, and at least one of them should develop a nonzero vacuum expectation value.…”

Probing a classically conformal B−L model with gravitational waves

“…In such cases, all the mass scales must be generated by dimensional transmutation such as Coleman-Weinberg mechanism [21]. Though it was found that this mechanism cannot be applied directly to the SM Higgs sector since the predicted Higgs mass ∼ 10 GeV is experimentally excluded, phenomenologically viable models still exist if one includes an additional scalar to the model so that the mass scale comes from the breaking of the conformal invariance of that field [22][23][24][25][26][27] (see also [28] for [25]). In Ref.…”