Higgs boson

In quantum field theory, particles are associated with fields; the Higgs boson is an excitation of the Higgs field, which is understood to exist throughout space. Unlike a stable object that can be seen directly, a Higgs boson decays extremely quickly. Experiments identify it from the characteristic patterns of particles produced in its decays. Measurements show that it has zero spin and no electric charge, consistent with the Standard Model Higgs boson.

The Higgs field helps explain why some fundamental particles have mass. In the Standard Model, interactions with the field account for the masses of the W and Z bosons and of elementary matter particles such as electrons and quarks; the photon does not interact with the field and remains massless. This is the Brout–Englert–Higgs mechanism. The Higgs boson is the field’s associated particle, not a little object that gives all ordinary matter its mass by sticking to it. In particular, most of the mass of protons and neutrons comes from the energy of the strong interaction binding their quarks and gluons, rather than directly from the Higgs mechanism.

In 1964, several groups of physicists independently proposed related mechanisms to reconcile the theory of the weak interaction with the observed masses of the W and Z bosons. The Nobel Prize in Physics 2013 recognized François Englert and Peter Higgs for the theoretical discovery of a mechanism that contributes to understanding the origin of mass of subatomic particles; Englert's work was done with Robert Brout. On 4 July 2012, the ATLAS and CMS collaborations at CERN announced that they had each observed a new particle with a mass near 125 giga-electronvolts, consistent with the predicted Higgs boson. Further measurements established that the new particle's properties matched key predictions of the Standard Model Higgs boson.

Because the Higgs boson decays almost immediately, experiments cannot observe it as a track crossing a detector. Instead, they search for combinations of decay products and compare the patterns with the expected backgrounds from other processes. The particle can decay in several ways, including into pairs of photons or into other heavy particles. The Particle Data Group's 2024 review gives a Higgs-boson mass of 125.20 ± 0.11 giga-electronvolts. The precise rate of its production and its interactions with other particles are measured to test whether it behaves as the Standard Model predicts.

The discovery confirmed an important part of the Standard Model, but it did not explain every question about mass or complete the description of nature. Researchers continue to test the Higgs boson's interactions and search for its self-interaction, as well as for deviations from the Standard Model or additional Higgs-like particles. These measurements may reveal where a more complete theory is needed; no such discovery follows automatically from the Higgs boson's existence.