Search for Dark Matter in association with a SM Higgs boson decaying to bb using 79.8/fb of pp collisions with the ATLAS detector

The search for events with large missing transverse momentum (MET) recoiling against a Standard Model (SM) particle is a probe for detecting Dark Matter (DM) at the LHC. The discovery of the Higgs boson h opens a new opportunity through the h+MET signature, with the highest probability for the Higgs boson to decay to bottom quarks. In this context, mono-Hbb is one of the most competitive channels, as it allows to probe a substantial region of the phase space, being complementary to many other “mono-X” searches. Over the last year, new techniques have been studied in order to overcome the current limitations due to jet merging in the boosted regime. The usage of Variable-Radius track jets for the reconstruction of the Higgs candidate in very dense environments has showed to strongly improve the sensitivity of the search and significantly outperform the previous results. The results are interpreted in the context of a simplified model Z’-2HDM which describes the interaction between DM and SM particles through new heavy mediator particles. The analysis of the data collected by the ATLAS detector from 2015 until 2017, corresponding to a total integrated luminosity of 79.8/fb, will then be presented in this talk.