Higgs boson decay is a research area within particle physics that focuses on the study of the decay process of the Higgs boson particle. The Higgs boson is a fundamental particle that was discovered in 2012 by the Large Hadron Collider (LHC) at CERN. Understanding how the Higgs boson decays is crucial for verifying the predictions of the Standard Model of particle physics and for gaining insights into the mechanism by which particles acquire mass. Researchers study the various possible decay modes of the Higgs boson, such as decay into pairs of photons, pairs of Z bosons, pairs of W bosons, or pairs of fermions. By analyzing the decay products and their properties, scientists can infer information about the properties and interactions of the Higgs boson. This research area is important for testing the validity of the Standard Model and for searching for new physics beyond the Standard Model.