Abstract
Precision measurements of the 125 GeV Higgs resonance recently discovered at the LHC have determined that its properties are similar to the ones of the Standard Model (SM) Higgs boson. However, the current uncertainties in the determination of the Higgs boson couplings leave room for significant deviations from the SM expectations. In fact, if one assumes no correlation between the top-quark and gluon couplings to the Higgs, the current global fit to the Higgs data lead to central values of the Higgs couplings to the bottom-quark and the top-quark that are about 2 σ away from the SM predictions. In a previous work, we showed that such a scenario could be realized in the Next to Minimal Supersymmetric extension of the SM (NMSSM), for heavy singlets and light MSSM-like Higgs bosons and scalar top quarks, but for couplings that ruined the perturbative consistency of the theory up to the GUT scale. In this work we show that a perturbative consistent scenario, for somewhat heavier stops, may be obtained in the presence of light singlets. An interesting bonus of this scenario is the possibility of explaining an excess of events observed in CP-even Higgs searches at LEP2.
Highlights
Higgs decay into bottom quarks, and to a subsequent enhancement of the branching ratios of the Higgs decay into vector gauge bosons
We showed that such a scenario could be realized in the Next to Minimal Supersymmetric extension of the Standard Model (SM) (NMSSM), for heavy singlets and light MSSM-like Higgs bosons and scalar top quarks, but for couplings that ruined the perturbative consistency of the theory up to the Grand Unification (GUT) scale
This solution cannot be realized in the Minimal Supersymmetric extension of the SM (MSSM) since it is difficult to obtain the right Higgs mass for such small values of tan β and the stop masses and, in addition, the Higgs mixing effects in this model lead to an enhancement of the Higgs bottom coupling and a suppression of the top one, that is the opposite as the tendency indicated by data
Summary
In order to enhance the associated production of h with a top quark pair (which we shall denote tth) in a model with two Higgs doublets the 125 GeV Higgs eigenstate must have a non-negligible component in the non-SM-like doublet. In a pure 2HDM, in which the coupling of the Higgs bosons to gluons is induced by loops of third generation quarks, enhanced tth is inevitably correlated with enhanced Higgs production in the gluon fusion channel, which is phenomenologically unacceptable One can avoid this correlation if there exist additional light colored states, such as stops, that give negative contribution to the effective Higgs coupling to gluons [9]. 260 GeV is allowed if the stop-LSP mass splitting is above about 20 GeV (but not large enough to make the stop decays to charm and neutralino subdominant) [29,30,31,32] Another important requirement to induce a large tth enhancement in the NMSSM with heavy singlets is that the value of λ 0.8 [9]. It is interesting to note that in principle large cot (β − α) may be obtained for very heavy non-SM Higgs doublet if |M H2 s| is large enough
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