Light Higgs scenario based on the TeV-scale supersymmetric strong dynamics

Abstract

We consider a model based on the supersymmetric QCD theory with N c = 2 and N f = 3. The theory is strongly coupled at the infrared scale Λ H . Its low energy effective theory below Λ H is described by the supersymmetric standard model with the Higgs sector that contains four iso-spin doublets, two neutral iso-spin singlets and two charged iso-spin singlets. If Λ H is at the multi-TeV to 10 TeV, coupling constants for the F-terms of these composite fields are relatively large at the electroweak scale. Nevertheless, the SM-like Higgs boson is predicted to be as light as 125 GeV because these F-terms contribute to the mass of the SM-like Higgs boson not at the tree level but at the one-loop level. A large non-decoupling effect due to these F-terms appears in the one-loop correction to the triple Higgs boson coupling, which amounts to a few tens percent. Such a non-decoupling property in the Higgs potential realizes the strong first order phase transition, which is required for a successful scenario of electroweak baryogenesis.Recently, the ATLAS and CMS experiments at the LHC [1] have reported an excess in the gamma-gamma mode at about 125 GeV, which may be a signal of the Higgs boson. In the Standard Model (SM), a light Higgs boson is the evidence of the weakly coupled Higgs sector. In models for physics beyond the SM, however, the light Higgs boson does not always correspond to a weakly coupled theory. The scenario based on little Higgs models [2] is an example of a strongly coupled theory with a light Higgs boson, where the Higgs boson arises as a pseudo Nambu-Goldstone boson originating from the breaking of some strongly interacting global symmetry at the TeV scale, and the Higgs boson mass is kept to be light. Supersymmetry (SUSY) is one of the most attractive candidates for the physics beyond the SM. SUSY can solve the gauge hierarchy problem, as the quadratic divergence in the radiative correction to the Higgs boson mass is cancelled owing to the non-renormalization theorem.In addition, elementary scalar fields are automatically introduced in the SUSY theory. The Higgs sector of the minimal SUSY extension of the SM (MSSM) necessarily contains two Higgs doublets. In the MSSM, the coupling constants in the Higgs potential are determined by the electroweak gauge couplings, and the mass of the SM-like Higgs boson is less than the Z boson mass at the tree level. With significant radiative corrections due to the large top Yukawa coupling [3], the Higgs mass can be pushed up to around 125 GeV in the case of very large stop masses or very large left-right stop mixing.Even within the framework based on SUSY, models with strongly coupled light Higgs boson can be constructed. A possible way is to introduce additional R-parity-even chiral superfields which strongly couple to the Higgs sector but the F-terms of which do not contribute to the Higgs boson four-point coupling. In this case, the SM-like Higgs boson is kept to be light. The strong couplings have rich phenomenological implications. First, radiative corrections...

Electroweak phase transition and Higgs boson couplings in the model based on supersymmetric strong dynamics

“…By developing the model in ref. [12], we may be able to build a fundamental UV complete model whose low-energy effective theory can explain baryogenesis, dark matter and tiny neutrino mass simultaneously below its confinement scale.…”

“…In this case, the model must be replaced by a more fundamental theory at the Landau pole. Recently, an ultraviolet (UV) complete framework has been proposed for an extended Higgs sector incorporating such large coupling constants [12], which is based on the SUSY SU(2) H gauge theory with six doublets, T 1 , ..., T 6 (N f = 3), and one singlet as a UV theory. This simple gauge structure was originally applied to the minimal supersymmetric fat Higgs model [13].…”

“…In ref. [12], the SU(2) H doublets T 1 , ..., T 6 are confined to give mesonic superfields [14], which are identified with the MSSM Higgs superfields and other exotic superfields in the extended Higgs sector. The Landau pole at which the coupling constants in the extended Higgs sector blow up is nothing but the confinement scale of the SU(2) H gauge theory.…”

“…[12]. First we evaluate the strength of EWPT and seek for parameter regions where strongly first order EWPT occurs, as is necessary for successful EWBG.…”

“…[12] contains four Higgs doublet, a pair of charged singlet and a pair of neutral singlet chiral superfields. In order to avoid flavor-changing neutral current, additional discrete Z 2 symmetry is imposed on the model, under which extra two doublets and all the singlets are odd.…”