Seminario di Fenomenologia delle Particelle Elementari
With the discovery of the Higgs boson in 2012, an extensive physics program has been carried out by the ATLAS experiment to characterize its properties. Among them, one of the most important is the coupling between the Higgs boson and the fermion, known as Yukawa coupling. Of particular interest is the coupling with the b-quark, the heaviest lepton accessible in the direct decay of the Higgs boson and therefore the one with highest branching ratio. Due to the overwhelming QCD background, an inclusive search for H- >bbar has tought to be impossible. However, with the development of theoretical and experimental techniques for boosted object, it was possible to find a strategy to probe the Higgs boson at high transverse momentum. During the seminar, I will discuss an inclusive search for the standard model Higgs boson produced with high transverse momentum decaying to a bottom-antibottom quark pair using a data-set of pp collisions at a center-ofmass energy of 13 TeV collected with the ATLAS experiment at the LHC. The data sample corresponds to an integrated luminosity of 80.5 fb−1. This is the first time the analysis is ever been performed within the ATLAS experiment. The analysis also provided a measurement of W/Z+jets processes in boosted regime with b-quarks final states observed at a significance of 5 standard deviation. A small excess, compatible at 1.6 sigma with the background-only hypothesis, is observed at 125 GeV. In addition, exclusions limits for dark matter resonant model are placed. The seminar will give an overview of the analysis along with its future perspective.