One possible signature of a Higgs boson from a simulated collision between two protons. It decays almost immediately into two jets ofhadrons and two electrons, visible as lines.[Note 1]
|Status||Tentatively observed – a boson"consistent with" the Higgs boson has been observed, but as of July 2012, scientists have not conclusively identified it as the Higgs boson.|
|Theorised||R. Brout, F. Englert, P. Higgs,G. S. Guralnik, C. R. Hagen, and T. W. B. Kibble (1964)|
|Discovered||tentatively announced July 4, 2012 (see above), by theATLAS and CMS teams at theLarge Hadron Collider|
|Types||1 in the Standard Model;
5 or more in supersymmetricmodels
|Mass||125.3±0.6 GeV/c2,∼126 GeV/c2|
|Mean lifetime||1 zeptosecond (10-21 s)
The Higgs boson or Higgs particle is a proposed elementary particle in the Standard Model of particle physics. The Higgs boson's existence would have profound importance in particle physics because it would prove the existence of the hypothetical Higgs field—the simplest of several proposed explanations for the origin of the symmetry-breaking mechanism by which elementary particles acquire mass.[Note 2] The leading explanation is that a field exists that has non-zero strength everywhere—even in otherwise empty space—and that particles acquire mass by interacting with this so-called Higgs field. If this theory is true, a matching particle—the smallest possible excitation of the Higgs field—should also exist and be detectable, providing a crucial test of the theory. Consequently, it has been the target of a long search in particle physics. One of the primary goals of the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland—the most powerful particle accelerator and one of the most complicated scientific instruments ever built—is to test the existence of the Higgs boson and measure its properties which would allow physicists to confirm this cornerstone of modern theory.
The Higgs boson is named for Peter Higgs who, along with two other teams, proposed the mechanism that suggested such a particle in 1964 and was the only one to explicitly predict the massive particle and identify some of its theoretical properties. In mainstream media it is often referred to as "the God particle", after the title of Leon Lederman's book on the topic (1993). Although the proposed particle is both important and elusive, the epithet is strongly disliked by physicists, who regard it as inappropriate sensationalism since the particle has nothing to do with God nor any mystical associations, and because the term is misleading: the crucial focus of study is to learn how the symmetry breaking mechanism takes place in nature - the search for the boson is part of, and a key step towards, this goal.
According to the Standard Model, the Higgs particle is a boson, a type of particle that allows multiple identical particles to exist in the same place in the samequantum state. It has no spin, electric charge, or colour charge. It is also very unstable, decaying into other particles almost immediately. If the Higgs boson were shown not to exist, other "Higgsless" models would be considered. In some extensions of the Standard Model there can be multiple Higgs bosons.
Proof of the Higgs field (by confirming its boson), and evidence of its properties, are seen as likely to greatly affect human understanding of the universe, validate the final unconfirmed part of the Standard Model as essentially correct, indicate which of several current particle physics theories are more likely correct, and open up "new" physics beyond current theories. On 4 July 2012, the CMS and the ATLAS experimental teams at the LHC independently announced that they each confirmed the formal discovery of a previously unknown boson of mass between 125–127 GeV/c2, whose behaviour so far was "consistent with" a Higgs boson, while adding a cautious note that further data and analysis were needed before positively identifying the new particle as being a Higgs boson of some type.