New results from the ATLAS and CMS experiments at the Large Hadron Collider (LHC) revealed how strongly the Higgs boson interacts with the heaviest known elementary particle, the top quark. Research team from The Center for Particle Science and Technology of University and Science and Technology of China of Chinese Academy of Sciences and the State Key Laboratory of Particle Detection and Electronics contributed much to the results.
It is the most important goal for the LHC to study the properties of Higgs boson following the discovery of Higgs particle in 2012. At the sixth LHC Physics Conference, ATLAS and CMS collaborations simultaneously announced their independent discoveries of "ttH production", a rare process where a pair of top quarks emits a Higgs boson. Both results were published on Physical Review D and Physical Review Letters, respectively.
As a significant part of this discovery, USTC-ATLAS research team led by Academician ZHAO Zhengguo conducted research work including detector operation, data reconstruction, physical research and detector upgrades during the ATLAS experiment.
In the study, WANG Rongkun and Dr. Rustem Ospanov of the team directly participated in the data analysis work. WANG made important contributions to the research of ZZ* decay channel and Rustem Ospanov used multivariate data analysis to suppress backgrounds from nonprompt and fake leptons, which played a decisive role in the discovery of multi-lepton decay channel.
Results provided direct evidence of the Yukama coupling between Higgs boson and top quarks by demonstrating significances exceeding 5 standard deviations, which will help scientist know more about the properties of the Higgs boson and reveal where to look for new physics.