Is Natural SUSY Natural?

Journal of High Energy Physics (Impact Factor: 5.62). 06/2013; 2013(10). DOI: 10.1007/JHEP10(2013)133
Source: arXiv

ABSTRACT We study the fine tuning associated to a `Natural Supersymmetry' spectrum
with stops, after RG running, significantly lighter than the first two
generation sfermions and the gluino. In particular, we emphasise that this
tuning should be measured with respect to the UV parameters of the theory, and
improve the accuracy of previous approximate expressions. It is found that, if
running begins at 10^16 GeV (10^5 GeV), decreasing the UV stop mass below 0.75
(0.4) of the weak scale Majorana gluino mass does not improve the overall fine
tuning of the theory. In contrast, it is possible to raise the first two
generation sfermion masses out of LHC reach without introducing additional
tuning. After running, regions of parameter space favoured by naturalness and
consistent with LHC bounds typically have IR stop masses of order 1.5 TeV (0.75
TeV), and fine tuning of at least 400 (50) for high (low) scale mediation. We
also study the fine tuning of theories with Dirac gluinos. These allow for
substantial separation of the gluino and sfermion masses and, regardless of the
scale of mediation, lead to relatively low fine tuning of order 50. Hence
viable models can still favour light stops, but this requires extra structure
beyond the MSSM field content.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In the NMSSM it is well possible to find an additional Higgs boson with a mass below 125 GeV which remains invisible in standard Higgs boson search channels. We study the Higgs pair production cross sections times branching fractions in this scenario, focusing on gluon fusion and the bb+tautau and bb+gammagamma final states. Summing over the SM-like and the lighter Higgs states, the production cross sections times branching fractions are never below the ones for SM Higgs pair production. Sizable enhancements of the signal rates are also possible, notably if a lighter Higgs state is produced. However, the rates involving at least one lighter Higgs boson are not always sufficiently large to guarantee its discovery.
    Journal of High Energy Physics 06/2013; · 5.62 Impact Factor


Available from