Search for exotic decays of the Higgs boson into b¯b and missing transverse momentum in pp collisions at √s = 13 TeV with the ATLAS detector

A search for the exotic decay of the Higgs boson (H) into a b¯b resonance
plus missing transverse momentum is described. The search is performed with the ATLAS detector at the Large Hadron Collider using 139 fb−1 of pp collisions at √s = 13 TeV. The search targets events from ZH production in an NMSSM scenario where H → ˜χ02 ˜χ01, with ˜χ02 → a ˜χ01, where a is a light pseudoscalar Higgs boson and ˜χ01,2 are the two lightest neutralinos. The decay of the a boson into a pair of b-quarks results in a peak in the
dijet invariant mass distribution. The final-state signature consists of two leptons, two or more jets, at least one of which is identified as originating from a b-quark, and missing transverse momentum. Observations are consistent with Standard Model expectations and upper limits are set on the product of cross section times branching ratio for a three-dimensional scan of the masses of the ˜χ02, ˜χ01 and a boson.