Abstract
The discovery of a relatively heavy Standard Model (SM) -like Higgs boson challenges naturalness of the minimal supersymmetric standard model (MSSM) from both Higgs and dark matter (DM) sectors. We study these two aspects in the MSSM extended by the low-scale inverse seesaw mechanism. Firstly, it admits a sizable radiative correction on the Higgs boson mass m_h, up to \sim 4 GeV in the case of an IR-fixed point of the coupling Y_\nu LH_u\nu^c and a large sneutrino mixing. Secondly, the lightest sneutrino, highly complex as expected, is a viable thermal DM candidate. Owing to the correct relic density and XENON100, two cases survive: a Higgs-portal complex DM with mass lying around the Higgs pole or above $W$ threshold, and a coannihilating DM with slim prospect of detection. Given an extra family of sneutrinos, both scenarios naturally work when we attempt to suppress the DM left-handed sneutrino component, confronting with enhancing m_h.
Highlights
To demonstrate the consequence of this property, we consider that the new Yukawa coupling develops an IR-fixed point, which predicts Yν ≃ 0.75
Specified to the low scale supersymmetric ISS, the sneutrino LSP is expected to be complex. This restricts the sneutrino dark matter (DM) into two possibilities: (I) Essentially it belongs to the Higgs-portal complex DM, and its mass has to be around mh/2 or above the W boson mass mW ; (II) It is a coannihilating DM, for example, the sneutrino LSP and Higgsino coannihilation
The discovery of a relatively heavy Standard Model (SM)-like Higgs boson is a good news to SUSY but not to the minimal supersymmetric standard model (MSSM), whose little hierarchy problem is exacerbated
Summary
The models equipped with a low scale seesaw mechanism receive special attentions, by virtue of its potential to be tested within our near future experiments. In the type-II and inverse seesaw mechanisms the smallness of mν has other origins, and the Higgs doublets are allowed to have large neutrino Yukawa couplings. The supersymmetric type-II seesaw mechanism can even enhance mh at the tree level [22] (it can simultaneously enhance the di-photon rate [22]). Such models are difficult to be embedded into a pertubative Grand Unified Theory (GUT) picture. We will first briefly review the minimal supersymmetric ISS mechanism, and discuss one of the new Yukawa couplings with the IR-fixed point behavior and its implication to the correction on the SM-like Higgs boson mass
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