Abstract
We address the question how light the lightest MSSM neutralino can be as dark matter candidate in a scenario where all supersymmetric scalar particles are heavy. The hypothesis that the neutralino accounts for the observed dark matter density sets strong requirements on the supersymmetric spectrum, thus providing an handle for collider tests. In particular for a lightest neutralino below 100 GeV the relic density constraint translates into an upper bound on the Higgsino mass parameter μ in case all supersymmetric scalar particles are heavy. One can define a simplified model that highlights only the necessary features of the spectrum and their observable consequences at the LHC. Reinterpreting recent searches at the LHC we derive limits on the mass of the lightest neutralino that, in many cases, prove to be more constraining than dark matter experiments themselves.
Highlights
The above sketched procedure has been recently employed by us to answer the question on how light the MSSM neutralino is still allowed to be by direct searches for electroweaklyinteracting supersymmetric particles at the LHC [4, 5]
We address the question how light the lightest MSSM neutralino can be as dark matter candidate in a scenario where all supersymmetric scalar particles are heavy
In particular for a lightest neutralino below 100 GeV the relic density constraint translates into an upper bound on the Higgsino mass parameter μ in case all supersymmetric scalar particles are heavy
Summary
As anticipated in the introduction, we are interested to study the phenomenology of the MSSM neutralino as a Dark Matter candidate in the low-mass regime, i.e. with mχ 100 GeV, in the case that only neutralinos and charginos are possibly light, while the rest of the spectrum, in particular the sfermions, might be decoupled. Let us comment about the possible role of the extra Higgses It is well known, that an s-channel exchange of the CP-odd Higgs A can provide an efficient annihilation mechanism for neutralino DM, especially close to the resonant condition mχ01 ≈ mA/2 and/or for a sizeable Higgsino component in χ01 [31]. [37]), and by rare decays such as Bs → μ+μ− [38] For these reasons, here we do not consider the possibility that the extended Higgs sector of the MSSM plays a role in the neutralino annihilation and we assume for simplicity that the heavy Higgses are decoupled. Gray points are excluded by one of the constraints listed in the text
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