Higgs boson decaying to a pair of bottom-quark is crucial for the validation of the Standard Model. The Higgs associated production with vector-boson (VH) channel provides leptonic signature, which can significantly suppress huge background from proton-proton collision. In this talk, observation of Higgs decays to bottom-quark pair (H->bbbar) using data collected by the ATLAS detector during 2015-2017 will be presented. As an important support to the VH and H->bbbar analysis, b-tagging efficiency calibration using Tag&Probe method will be discussed as well.

Dr. Changqiao Li obtained doctoral degree from Sorbonne University (Paris, France) and University of Science and Technology of China in 2018.12. He is postdoctoral Researcher in USTC. He has been actively involved in Higgs analysis and b-tagging performance studies in ATLAS experiment, such as observation of VH and H->bbbar and measurement of its differential cross sections, perspective studies for Higgs cross section measurement at the high-luminosity LHC, as well as calibration of the algorithm of b-jet identification.