Search for the decay of the Higgs boson into two nMSSM pseudo-scalar particles

The next-to-minimal supersymmetric Standard Model (nMSSM) predicts the existence of a light pseudo-scalar boson "$a$" and the decay of the Higgs boson into a pair of such particles. This particle is searched for in several final states sensitive to different decay modes and mass ranges of the hypothetical pseudo-scalar, using ATLAS data amounting to either $20.3$ fb$^{-1}$ of $p$-$p$ collisions at $\sqrt{s} = 8 \,$ TeV or between $3.2$ fb$^{-1}$ and $36.1$ fb$^{-1}$ at $\sqrt{s} = 13 \,$ TeV.