Search for Dark Matter Produced in Association with a Dark Higgs Boson Decaying to two b-quarks Using full Run-2 data set from the ATLAS detector

A hypothetical dark Higgs boson was proposed in a dark matter (DM) model to explain the origin of mass in dark sector as well as to open up a new annihilation channel relaxing the DM relic density constraint from cosmological observation. The search focusing on Majorana DM produced with a low mass dark Higgs boson decaying to two b-quarks is proposed and working in progress using the 139 fb^-1 of proton-proton collision data collected with the ATLAS detector at √s=13 TeV.

The event selection and categorization are optimized based on the varying dark Higgs mass. Advanced jet clustering and boosted tagging techniques are applied to achieve higher efficiency and better signal over background ratio. The analysis method and model interpretation strategy together with the result of expected sensitivity will be presented.