Light stops, heavy Higgs, and heavy gluinos in supersymmetric standard models with extra matters

Abstract

We have explored the possibilities of scenarios with heavy gluinos and light stops in supersymmetric (SUSY) standard models with extra vector-like multiplets. If we assume the hierarchical structure for soft masses of the minimal supersymmetric standard model (MSSM) scalar fields and extra scalars, the light stop and the observed Higgs boson can be realized. While the stau is the lightest SUSY particle (LSP) in broad parameter space, we have found that the neutralino LSP is realized in the case that the non-zero soft parameters for the MSSM Higgs doublets or the non-universal gaugino masses are assumed. arXiv:1611.07670v2 [hep-ph] 5 Apr 2017Supersymmetry (SUSY) is one of the promising extensions of the standard model (SM). New particles, with opposite spin statistics to the SM particles, are naturally introduced by extending spacetime to one with Grassmann coordinates. If these new particles, called sparticles, lie around the TeV scale, SUSY provides us with some phenomenological implications. The lightest supersymmetric particle (LSP) may explain the dark matter abundance in the universe. The gauge coupling unification also works well, and is compatible with grand unification theories (GUTs).The ATLAS and CMS collaborations found a scalar boson consistent with the SM Higgs boson [1,2], and reported that its mass is around 125 GeV [3]. In the minimal supersymmetric standard model (MSSM), the light Higgs boson mass is bounded from above at tree level. To explain the observed Higgs boson mass, several ideas have been proposed: the introduction of large quantum corrections to the light Higgs mass, adding vector-like extra matters [4,5], pushing up the SUSY breaking scale [6,7], realizing large A-term or next-to-MSSM [8], and so on.There is also no signal of sparticles and no significant deviation from the SM predictions at the LHC experiments (e.g., see Refs. [9,10]). In particular, the masses of new colored particles are severely constrained; for instance, gluinos should be heavier than about 1.9 TeV in a simplified mass spectrum [11].Heavy gluinos naïvely indicate heavy squarks at the low-energy scale. In fact, in order to obtain the heavy gluinos at the low-energy scale, we require a large value for the gluino mass at an initial scale (such as the GUT scale ∼ 10 16 GeV or the Planck scale ∼ 10 18 GeV). According to renormalization group equation (RGE) analysis, heavy gluinos at the input scale lead to heavy squarks and a large A-term at the one-loop order in the MSSM. The heavy stop is unfavorable from the naturalness point of view since it requires fine-tuning between the soft mass and the supersymmetric mass for the up-type MSSM Higgs doublet.There are other things to be considered in the supersymmetric extended models: SUSY flavor problems. To suppress the flavor-changing neutral current (FCNC) processes, it is required that the sfermion masses for the first two generations are degenerate, decoupled, and/or aligned. Many models have been constructed assuming that SUSY breaking is mediated by gauge interactions...