HiggsBoson

The Higgs boson is a fundamental particle within the Standard Model of particle physics. It is the quantum excitation of the Higgs field, a scalar field that permeates all space. Through the Higgs mechanism, interactions with this field give mass to the W and Z bosons and, via Yukawa couplings, to the fermions. The Higgs boson itself is the elementary excitation of the field around its vacuum expectation value.

The particle was proposed in 1964 by Peter Higgs and independently by others as part of the mechanism that breaks electroweak symmetry. Experimental confirmation came in 2012 from the Large Hadron Collider at CERN, with the ATLAS and CMS experiments observing a new boson with a mass around 125 GeV. Subsequent analyses established its properties as consistent with those expected for the Standard Model Higgs boson.

The Higgs is a neutral, spin-0 particle. Its couplings to other particles increase with their mass. It decays through several channels, including two photons, four leptons from ZZ decays, WW decays, bottom quark pairs, and tau lepton pairs; branching ratios depend on the Higgs mass. At the LHC, dominant production occurs via gluon-gluon fusion, with additional contributions from vector boson fusion, associated production with a W or Z boson, and production in association with top quarks (ttH).

Significance and status: The discovery completed the Standard Model’s description of electroweak symmetry breaking and mass generation. Measurements of the Higgs mass and couplings continue to test the model, and so far results are compatible within experimental uncertainties. Open questions remain regarding naturalness and possible physics beyond the Standard Model.