Extra vectorlike matter and the lightest Higgs scalar boson mass in low-energy supersymmetry

Physical review D: Particles and fields (Impact Factor: 4.86). 02/2010; 81(3):035004-035004. DOI: 10.1103/PHYSREVD.81.035004
Source: arXiv


The lightest Higgs scalar boson mass in supersymmetry can be raised significantly by extra vectorlike quark and lepton supermultiplets with large Yukawa couplings but dominantly electroweak-singlet masses. I consider models of this type that maintain perturbative gauge coupling unification. The impact of the new particles on precision electroweak observables is found to be moderate, with the fit to Z-pole data as good or better than that of the standard model even if the new Yukawa couplings are as large as their fixed-point values and the extra vectorlike quark masses are as light as 400 GeV. I study the size of corrections to the lightest Higgs boson mass, taking into account the fixed-point behavior of the scalar trilinear couplings. I also discuss the decay branching ratios of the lightest new quarks and leptons and general features of the resulting collider signatures.

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    • "Both the charged-current [17] and the flavor changing neutral current (FCNC) [18] [19] decay processes are allowed. The ratio of the predicted rates depends on the model: in some models the FCNC process dominates [20]; in others the two modes are comparable in rate. "
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    • "The results of the search are interpreted in the context of vector-like lepton [16] and type-III seesaw [17] scenarios in which the new heavy leptons decay through mixing with electrons or muons () induced by off-diagonal Yukawa couplings. In the type-III seesaw model, the masses of the three heavy leptons are assumed to be identical. "
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