Search for a Higgs Boson in Association with a Pair of Top Quarks with the ATLAS Detector

The production of a Higgs boson in association with a pair of top quarks ($t \bar tH$) is one of the main Higgs production channels at the LHC which is yet unobserved. In the recent publications, the ATLAS Collaboration claims evidence for the process using the data collected in 2015 and 2016 at the LHC. The process offers direct sensitivity to the top-Yukawa coupling which is the largest fermion coupling to the Higgs. Any deviation of the top-Yukawa coupling measured directly and compared to indirect constraints would provide a hint towards new physics. In the context of $t \bar tH$, the $H \rightarrow b \bar b$ decay is of particular interest due to the large branching ratio and it is, therefore, potentially offering high sensitivity to the top-Yukawa coupling. The goal of this paper is to summarize the recent progress in $t \bar tH(b \bar b)$ analysis contrasting the strategy employed by ATLAS in 2016 with the new publication in 2017.