Probing mild-tempered neutralino dark matter through top-squark production at the LHC

Abstract

The lightest neutralino, assumed to be the lightest supersymmetric particle, is proposed to be a dark matter (DM) candidate for the mass $\mathcal{O}(100)\text{ }\text{ }\mathrm{GeV}$. Constraints from various direct dark matter detection experiments and Planck measurements exclude a substantial region of parameter space of minimal supersymmetric standard model. However, a ``mild-tempered'' neutralino with dominant bino composition and a little admixture of Higgsino is found to be a viable candidate for DM. Within the minimal supersymmetric standard model framework, we revisit the allowed region of parameter space that is consistent with all existing constraints. Regions of parameters that are not sensitive to direct detection experiments, known as ``blind spots,'' are also revisited. Complimentary to the direct detection of DM particles, a mild-tempered neutralino scenario is explored at the LHC with the center of mass energy $\sqrt{\mathrm{s}}=13\text{ }\text{ }\mathrm{TeV}$ through the top-squark pair production, and its subsequent decays with the standard-model-like Higgs boson in the final state. Our considered channel is found to be very sensitive also to the blind spot scenario. Detectable signal sensitivities are achieved using the cut-based method for the high luminosity options 300 and $3000\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, which are further improved by applying the multivariate analysis technique.