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Register a new userHiggs boson decays in the Complex MSSM
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The analysis of the Higgs search results at LEP showed that a part of the MSSM parameter space with non-zero complex phases could not be excluded, where the lightest neutral Higgs boson, h_1, has a mass of only about 45 GeV and the second lightest neutral Higgs boson, h_2, has a sizable branching fraction into a pair of h_1 states. Full one-loop results for the Higgs cascade decay h_2 --> h_1 h_1 are presented and combined with two-loop Higgs propagator corrections taken from the program FeynHiggs. Using the improved theoretical prediction to analyse the limits on topological cross sections obtained at LEP, the existence of an unexcluded region at low Higgs mass is confirmed. The effect of the genuine vertex corrections on the size and shape of this region is discussed.
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We discuss various improvements of the prediction for the light MSSM Higgs boson mass in the hybrid framework of the public code FeynHiggs, which combines fixed-order and effective field theory results. First, we discuss the resummation of logarithmic contributions proportional to the bottom-Yukawa coupling including two-loop $Delta_b$ resummation. For large $tanbeta$, these improvements can lead to large upward shifts of the Higgs mass compared to the existing fixed-order calculations. Second, we improve the implemented EFT calculation by fully taking into account the effect of $mathcal{CP}$-violating phases. As a third improvement, we discuss the inclusion of partial N$^3$LL resummation. The presented improvements will be implemented into FeynHiggs.
Recently, the Higgs boson masses in the Minimal Supersymmetric Standard Model (MSSM) and their mixing have been calculated using the complex Two-Higgs-DoubletModel (cTHDM) as an effective field theory (EFT) of the MSSM. Here, we discuss the implementation of this calculation, which we improve in several aspects, into the hybrid framework of FeynHiggs by combing the cTHDM-EFT calculation with the existing fixed-order calculation. This combination allows accurate predictions also in the intermediate regime where some SUSY particles are relatively light, some relatively heavy and some in between. Moreover, the implementation provides precise predictions for the Higgs decay rates and production cross-sections.
The remaining theoretical uncertainties from unknown higher-order corrections in the prediction for the light Higgs-boson mass of the MSSM are estimated. The uncertainties associated with three different approaches that are implemented in the publicly available code FeynHiggs are compared: the fixed-order diagrammatic approach, suitable for low SUSY scales, the effective field theory (EFT) approach, suitable for high SUSY scales, and the hybrid approach which combines the fixed-order and the EFT approaches. It is demonstrated for a simple single-scale scenario that the result based on the hybrid approach yields a precise prediction for low, intermediate and high SUSY scales with a theoretical uncertainty of up to $sim 1.5$ GeV for large stop mixing and $sim 0.5$ GeV for small stop mixing. The uncertainty estimate of the hybrid calculation approaches the uncertainty estimate of the fixed-order result for low SUSY scales and the uncertainty estimate of the EFT approach for high SUSY scales, while for intermediate scales it is reduced compared to both of the individual results. The estimate of the theoretical uncertainty is also investigated in scenarios with more than one mass scale. A significantly enhanced uncertainty is found in scenarios where the gluino is substantially heavier than the scalar top quarks. The uncertainty estimate presented in this paper will be part of the public code FeynHiggs.
We present the full next-to-leading order (NLO) supersymmetric (SUSY) electroweak and SUSY-QCD corrections to the decay widths of the charged Higgs boson decays into on-shell final states in the framework of the CP-conserving and CP-violating Next-to-Minimal Supersymmetric Model (NMSSM). The newly calculated corrections have been implemented in the code NMSSMCALCEW. In these proceedings, we discuss the impact of the NLO corrections on the charged Higgs boson branching ratios in a wide range of the parameter space that is still compatible with the experimental constraints. We also investigate the effect of CP violation in these corrections.
In the MSSM with complex parameters loop corrections to the decays $H^+ to t bar{b}$ and $H^- to bar{t} b$ with $t to b W$ and $W to l u$ lead to CP-violating asymmetries: a decay rate asymmetry, a forward-backward asymmetry and an energy asymmetry. We derive explicit formulas for them and perform a detailed numerical analysis. We study the dependence on the parameters and the phases involved. In particular, the influence of the running Yukawa coupling is taken into account. The decay rate asymmetry can go up to 25%, the forward-backward and the energy asymmetry up to 10%.
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