The Higgs boson is an elementary boson in the Standard Model of particle physics. It is the quantum excitation of the Higgs field, which has a nonzero value even in empty space and enables many fundamental particles to acquire mass. Its discovery by the ATLAS and CMS experiments at CERN in 2012 provided experimental confirmation of a central element of electroweak theory. The particle has a mass of approximately 125 GeV/c² and is distinguished from other known elementary particles by its zero spin. (home.cern)
Field and mass generation
In quantum field theory, particles are excitations of underlying fields. The Higgs field is therefore not a collection of Higgs bosons distributed through space: its persistent background value and the short-lived particles produced by exciting it are distinct aspects of the same field. Discovering the particle made it possible to test the field’s interactions experimentally. (home.cern)
The Higgs mechanism, also called the Brout–Englert–Higgs mechanism, explains how the W and Z bosons acquire mass within the electroweak interaction. Through spontaneous symmetry breaking, the field’s lowest-energy configuration does not exhibit the full symmetry of the underlying equations. Interactions with this background produce the masses of the W and Z particles without abandoning the theory’s gauge structure. The photon remains massless. (home.cern)
Matter particles, or fermions, acquire mass through another type of interaction with the Higgs field, known as a Yukawa interaction. In the Standard Model, stronger Yukawa coupling corresponds to greater particle mass. Measurements involving the top and bottom quarks and the tau lepton have experimentally established this relationship for these heavy matter particles. The theory does not, however, predict why their individual coupling strengths have the values observed. (home.cern)
The Higgs field is not responsible for all mass. Most of the mass of a proton or neutron arises from the dynamics of the strong interaction, rather than directly from the masses of its constituent quarks. Consequently, saying that the Higgs boson “gives everything its mass” confuses both the particle with its field and elementary-particle mass with the mass of composite matter. (home.web.cern.ch)
Theoretical origins
In 1964, François Englert and Robert Brout, Peter Higgs, and Gerald Guralnik, Carl Richard Hagen and Tom Kibble developed related proposals explaining how particles could acquire mass in gauge theories. These contributions supplied the mechanism that became central to the electroweak Standard Model. The associated particle became known as the Higgs boson. (indico.cern.ch)
The mechanism predicted an experimentally accessible scalar particle, but did not determine its mass. Searches therefore had to examine a range of possible masses and decay signatures. Following the eventual discovery, Englert and Higgs jointly received the 2013 Nobel Prize in Physics for their theoretical contribution to understanding the origin of subatomic-particle mass. (home.cern)
Experimental discovery
On July 4, 2012, the ATLAS and CMS collaborations announced independent observations of a new particle near 125–126 GeV at CERN’s Large Hadron Collider (LHC). Both reported signals at approximately the five-standard-deviation discovery threshold. The announcement initially described a particle consistent with the predicted Higgs boson, rather than claiming that all its properties had already been established. (home.cern)
The Higgs boson decays too rapidly to leave a directly observable detector track. Experiments instead measure its decay products and reconstruct their combined invariant mass. A concentration of events near the same mass, above the expected background, provides evidence for production of the parent particle. Two especially important discovery signatures were decay into two photons and decay through Z bosons into four leptons. (home.web.cern.ch)
The significance of an excess is assessed using statistics. Five sigma corresponds to a background-fluctuation probability of roughly one in 3.5 million under the specified statistical assumptions; it is not the probability that the entire theory is false. Further analysis of decay-product directions established the particle’s spin-zero character, and by March 2013 the accumulated evidence supported its identification as a Higgs boson. (home.web.cern.ch)
Properties, production and decay
The observed Higgs boson has zero electric charge and zero intrinsic angular momentum, or spin. Its lifetime is of order 10⁻²² seconds. Unlike its mass, which must be measured, its production and decay properties can be calculated within the Standard Model once the mass and other model parameters are specified. (home.web.cern.ch)
At the LHC, the dominant production process is gluon fusion, mediated principally by a top-quark loop. Other important processes include fusion of W or Z bosons and production alongside a W or Z boson or top quarks. Studying these different processes helps separate and measure the Higgs particle’s interactions. (atlas.cern)
For a mass near 125 GeV/c², the Standard Model predicts that approximately 58% of Higgs bosons decay into bottom-quark–antiquark pairs. Other channels include W and Z bosons, tau leptons, gluons and photons. A common decay is not necessarily easy to detect: bottom quarks are produced abundantly through unrelated processes, whereas rarer photon and four-lepton signatures offer cleaner experimental identification. (home.cern)
Research questions
Precision measurements test whether the particle’s couplings match Standard Model predictions or reveal additional interactions. Searches also examine possible invisible decays and connections to dark matter, without any established Higgs–dark-matter interaction. (home.cern)
A major target is the Higgs self-coupling, which describes its interaction with itself and probes the shape of the field’s potential. Higgs-pair production is particularly sensitive to this quantity. An ATLAS result published in April 2026 placed tighter limits on the self-coupling using a channel in which one Higgs decays into photons and the other into bottom quarks; it constrained the interaction rather than precisely determining its value. (home.cern)