2012 Higgs Boson Observation

On 4 July 2012, the ATLAS and CMS collaborations at the Large Hadron Collider independently announced they had each observed a new particle, in the mass region around 125 GeV, consistent with the long-predicted Higgs boson: no electric charge, short-lived, and decaying in the ways the theory forecast. The Higgs boson appears in roughly one collision in a billion, so the finding rested on combing enormous volumes of collision data for a statistically significant excess rather than seeing any single event directly. By March 2013, further analysis of spin and other properties confirmed the particle was a Higgs boson, completing the last unconfirmed piece of the Standard Model of particle physics and experimentally validating the mechanism Brout, Englert and Higgs had proposed 48 years earlier.