Abstract
A highly bino-like Dark Matter (DM), which is the Lightest Supersymmetric Particle (LSP), could be motivated by the stringent upper bounds on the DM direct detection rates. This is especially so when its mass is around or below 100 GeV for which such a bound tends to get most severe. Requiring not so large a higgsino mass parameter, that would render the scenario reasonably ‘natural’, prompts such a bino-like state to be relatively light. In the Minimal Supersymmetric Standard Model (MSSM), in the absence of comparably light scalars, such an excitation, if it has to be a thermal relic, is unable to meet the stringent experimental upper bound on its abundance unless its self-annihilation hits a funnel involving either the Z-boson or the Standard Model (SM)-like Higgs boson. We demonstrate that, in such a realistic situation, a highly bino-like DM of the popular Z3-symmetric Next-to-Minimal Supersymmetric Standard Model (NMSSM) is viable over an extended range of its mass, from our targeted maximum in the vicinity of the mass of the top quark down to about 30 GeV. This is facilitated by the presence of comparably light singlet-like states that could serve as funnel (scalars) and/or coannihilating (singlino) states even as the bino-like LSP receives a minimal (but optimal) tempering triggered by suitably light higgsino states that, in the first place, evade stringent lower bounds on their masses that can be derived from the Large Hadron Collider (LHC) experiments only in the presence of a lighter singlino-like state. An involved set of blind spot conditions is derived for the DM direct detection rates by considering for the very first time the augmented system of neutralinos comprising of the bino, the higgsinos and the singlino which highlights the important roles played by the NMSSM parameters ‘λ’ and tan β in delivering a richer phenomenology.
Highlights
Of Dark Matter (DM) states mediated by such sfermions are optimally efficient [1,2,3,4] and/or (ii) if there is an efficient coannihilation of such a DM state with slepton(s)
An involved set of blind spot conditions is derived for the DM direct detection rates by considering for the very first time the augmented system of neutralinos comprising of the bino, the higgsinos and the singlino which highlights the important roles played by the Next-to-Minimal Supersymmetric Standard Model (NMSSM) parameters ‘λ’ and tan β in delivering a richer phenomenology
A highly bino-like DM can be motivated from an ever diminishing upper bound on the DM Direct Detection (DMDD) cross sections
Summary
Where WMSSM|μ=0 is the MSSM superpotential without the higgsino mass term (the socalled μ-term), Hu, Hd are the SU(2) Higgs doublet superfields of the MSSM while S is the gauge singlet superfield of the NMSSM. ‘λ’ and ‘κ’ are dimensionless coupling constants for the interaction among the doublet and the singlet fields and the self-interaction of the singlet field, respectively. The symmetric squared mass matrix for the CP -even scalars in the basis HjR = {HdR, HuR, SR} is given by [39]. The symmetric squared mass matrix for the CP -odd scalars in the basis HjI = {HdI , HuI , SI } is given by [39]. The first and the second terms stand for the tree-level MSSM and NMSSM contributions, respectively, while ∆mix stems from a possible singlet-doublet mixing and, in the weak mixing limit (as is favored by the LHC data), is given by [109]. Where mt stands for the mass of the SM top quark, MS = √mt1mt, mt1(t2) being the mass of the lighter (heavier) physical top squark state and Xt = At − μeff cot β, At being the soft trilinear coupling for the top sector. As we will find, such correlations (or, for that matter, their absence) could crucially govern their collective phenomenology
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