The ATLAS Experiment at CERN laboratory observed direct interaction of Higgs boson and top quark

The observation of associated production of the top quark pair and the Higgs Boson is a process where direct interaction of these two heaviest particles of the Standard model of elementary particles comes into play. The production of the Higgs boson is accompanied with the top quark pair creation only in about 1% of events and for the observation of this process data from several decay channels have been combined. Statistical analysis included multivariety technique called Boosted Decision Trees that helped to discover the signal and mass peak of the Higgs boson. The observation of this interaction represents one of the precise tests of the Higgs mechanism that gives mass to the particles. The peculiarity is the observed frequency of teh process that is by one standard deviaton larger than predicted by the Standard model. The study of the interaction of the Higgs boson and top quark is the key to understand the violation of electroweka symmetry in the microworld, the test of the possible special role the heaviest quark and an open door for searching of new interactions and particles beyond the Standard model. The current observation included data from 2015-2017 while the LHC accelerator delivers proton collisions at 13 TeV energy also this year, before the planned temporary shutdown in 2019-2020.

Links:
http://atlas.cern/updates/physics-briefing/observation-tth-production
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2018-13/