Search for the Standard Model Higgs boson produced in association with top quarks and decaying into a $b\bar{b}$-pair in pp collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector at the LHC

A search for the Standard Model Higgs boson produced in association with a pair of top quarks ($t\bar{t}H$) and decaying into a pair of bottom quarks ($H \to b \bar{b}$) is presented. The search is focused on the semileptonic decay of the $t\bar{t}$ system and exploits different topologies given by the jet and b-tagged jet multiplicities of the event. A neural network is used to discriminate between signal and background events, the latter being dominated by $t\bar{t}$ + jets production. Using 20.3/fb of data at $\sqrt{s}$ = 8 TeV collected with the ATLAS detector during Run 1 of the Large Hadron Collider, we obtain an observed (expected) 95% confidence-level upper limit of 3.6 (2.6) times the Standard Model cross section for a Higgs boson with a mass of 125 GeV.