Abstract

After the discovery of the Higgs boson in 2012, data collected by ATLAS at LHC at a centre-of-mass energy of 7 and 8 TeV have been used to search for its coupling to fermions and bosons in the various production modes. The coupling with top quarks is of particular relevance to probe the Standard Model (SM) predictions against new physics contributions both at production (direct measurement) and at decay, for example into two photons. After describing the experimental strategy, optimization of selections and main backgrounds to the process under study, results will be shown for the search of a Higgs boson with a ttbar pair in various final states (bbbar, with many leptons, di-photon). While no signal observation can be claimed with the data set at hand, a sensitivity to cross-section values close to the SM expectation is attained: which makes this a ‘hot topic’ for the first phase of the LHC second data taking, starting now.