In 2012, the final missing particle of the SM, the Higgs boson, was observed by the ATLAS 1 and CMS 2, 3 collaborations at CERN. The SM has been very successful in providing accurate predictions for essentially all particle physics experiments carried out so far. These vector bosons are the massless photons (gluons) for the electromagnetic (strong) interaction, and the heavy W and Z bosons for the weak interaction. (In quantum mechanics, spin is an intrinsic form of angular momentum carried by elementary particles). The established theory of elementary particle physics, commonly referred to as the standard model (SM), provides a complete description of the electromagnetic, weak and strong interactions of matter particles, which are spin-1/2 fermions, through three different sets of mediators, which are spin-1 bosons. An order of magnitude larger number of Higgs bosons, expected to be examined over the next 15 years, will help deepen our understanding of this crucial sector. Several of the standard model issues originate in the sector of Higgs boson physics. Much evidence points to the fact that the standard model is a low-energy approximation of a more comprehensive theory. Within the uncertainties, all these observations are compatible with the predictions of the standard model of elementary particle physics. Here the CMS Collaboration reports the most up-to-date combination of results on the properties of the Higgs boson, including the most stringent limit on the cross-section for the production of a pair of Higgs bosons, on the basis of data from proton–proton collisions at a centre-of-mass energy of 13 teraelectronvolts. The CMS experiment has observed the Higgs boson in numerous fermionic and bosonic decay channels, established its spin–parity quantum numbers, determined its mass and measured its production cross-sections in various modes. Ten years later, and with the data corresponding to the production of a 30-times larger number of Higgs bosons, we have learnt much more about the properties of the Higgs boson.
In July 2012, the ATLAS and CMS collaborations at the CERN Large Hadron Collider announced the observation of a Higgs boson at a mass of around 125 gigaelectronvolts.
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