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

ABSTRACT 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.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this article we propose a new strategy to address the Little Hierarchy problem. We show that the addition of a fourth generation with vector-like quarks to the minimal supersymmetric standard model (MSSM) can raise the predicted value of the physical Higgs mass by mixing with the top sector. The mixing requires a larger top quark Yukawa coupling (by up to $\sim 6 %$) to produce the same top mass. Since loop corrections to $m_h$ go as $y_{top}^4$, this will in turn increase the predicted value of the physical Higgs mass, a point not previously emphasized in the literature. In the presence of mixing, for A-terms and soft masses around 900 GeV, a Higgs mass of 125 GeV can be generated while retaining perturbativity of the gauge couplings, evading constraints from electroweak precision measurements (EWPM) and recent LHC searches, and pushing the Landau pole for the top Yukawa above the GUT scale. Soft masses can be as low as 800 GeV in parts of parameter space with a Landau pole at $\sim 10^{10}$ GeV. However, the Landau pole can still be pushed above the GUT scale if one sacrifices perturbative unification by adding fields in a $\mathbf{5}$+$\mathbf{\bar{5}}$ representation. With a ratio of weak-scale vector masses $\neq 1$, soft masses may be slightly below $800$ GeV. The model predicts new quarks and squarks with masses $\gtrapprox 750$ GeV. We briefly discuss potential paths for discovery or exclusion at the LHC.
    Physical Review D 05/2014; 90(3). DOI:10.1103/PhysRevD.90.035024 · 4.86 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The nucleon decay is a significant phenomenon to verify grand unified theories (GUTs). For the precise prediction of the nucleon lifetime induced by the gauge bosons associated with the unified gauge group, it is important to include the renormalization effects on the Wilson coefficients of the dimension-six baryon number violating operators. In this study, we have derived the threshold corrections to these coefficients at the one-loop level in the minimal supersymmetric SU(5) GUT and the extended one with additional $SU(5)$ vector-like pairs. As a result, it is found that the nucleon decay rate is suppressed about 5% in the minimal setup, and then the suppression could be $O(10)$% in the vector-like matter extensions.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We compute the one loop corrections to the CP even Higgs mass matrix in the supersymmetric inverse seesaw model to single out the different cases where the radiative corrections from the neutrino sector could become important. It is found that there could be a significant enhancement in the Higgs mass even for Dirac neutrino masses of $\mathcal{O}$(30) GeV if the left-handed sneutrino soft mass is comparable or larger than the right-handed neutrino mass. In the case where right-handed neutrino masses are significantly larger than the supersymmety breaking scale, the corrections can utmost account to an upward shift of 3 GeV. For very heavy multi TeV sneutrinos, the corrections replicate the stop corrections at 1-loop. We further show that general gauge mediation with inverse seesaw model naturally accommodates a 125 GeV Higgs with TeV scale stops.
    Physics Letters B 05/2014; 736. DOI:10.1016/j.physletb.2014.08.002 · 6.02 Impact Factor


Available from