Editing Weak interaction (section)

== Electroweak theory ==
{{main article|Electroweak interaction}}
The [[Standard Model]] of particle physics describes the [[electromagnetic interaction]] and the weak interaction as two different aspects of a single electroweak interaction. This theory was developed around 1968 by [[Sheldon Glashow]], [[Abdus Salam]], and [[Steven Weinberg]], and they were awarded the [[Nobel Prize in Physics#1970s|1979 Nobel Prize in Physics]] for their work.<ref>{{cite web |publisher=Nobel Media |work=NobelPrize.org |title=The Nobel Prize in Physics 1979 |url=http://nobelprize.org/nobel_prizes/physics/laureates/1979/ |access-date=26 February 2011}}</ref> The [[Higgs mechanism]] provides an explanation for the presence of [[W and Z bosons|three massive gauge bosons]] ({{math|{{SubatomicParticle|W boson+}}}}, {{math|{{SubatomicParticle|W boson-}}}}, {{math|{{SubatomicParticle|Z boson0}}}}, the three carriers of the weak interaction), and the [[photon]] ({{math|γ}}, the massless gauge boson that carries the electromagnetic interaction).<ref name="PDGHiggs">
{{cite journal
 |author=C. Amsler ''et al.'' ([[Particle Data Group]])
 |year=2008
 |title=Review of Particle Physics – Higgs Bosons: Theory and Searches
 |url=http://pdg.lbl.gov/2008/reviews/higgs_s055.pdf
 |journal=[[Physics Letters B]]
 |volume=667 |issue= 1|pages=1–6
 |doi= 10.1016/j.physletb.2008.07.018
 |bibcode = 2008PhLB..667....1A
 |hdl=1854/LU-685594
 |s2cid=227119789
 |hdl-access=free
}}
</ref>

According to the electroweak theory, at very high energies, the universe has four components of the [[Higgs field]] whose interactions are carried by four massless scalar [[boson]]s forming a complex scalar Higgs field doublet. Likewise, there are four massless electroweak vector bosons, each similar to the [[photon]]. However, at low energies, this gauge symmetry is [[spontaneous symmetry breaking|spontaneously broken]] down to the {{math|U(1)}} symmetry of electromagnetism, since one of the Higgs fields acquires a [[vacuum expectation value]]. Naïvely, the symmetry-breaking would be expected to produce three massless [[Goldstone boson|bosons]], but instead those "extra" three Higgs bosons become incorporated into the three weak bosons, which then acquire mass through the [[Higgs mechanism]]. These three composite bosons are the {{math|{{SubatomicParticle|W boson+}}}}, {{math|{{SubatomicParticle|W boson-}}}}, and {{math|{{SubatomicParticle|Z boson0}}}}&nbsp;bosons actually observed in the weak interaction. The fourth electroweak gauge boson is the photon ({{mvar|γ}}) of electromagnetism, which does not couple to any of the Higgs fields and so remains massless.<ref name="PDGHiggs"/>

This theory has made a number of predictions, including a prediction of the masses of the {{math|{{SubatomicParticle|Z boson}}}} and {{math|{{SubatomicParticle|W boson}}}}&nbsp;bosons before their discovery and detection in 1983.

On 4&nbsp;July 2012, the CMS and the ATLAS experimental teams at the [[Large Hadron Collider]] independently announced that they had confirmed the formal discovery of a previously unknown boson of mass between 125 and {{val|127|u=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 boson as being a Higgs boson of some type. By 14&nbsp;March 2013, a Higgs boson was tentatively confirmed to exist.<ref>{{cite web |url=http://home.web.cern.ch/about/updates/2013/03/new-results-indicate-new-particle-higgs-boson |title=New results indicate that new particle is a Higgs boson |date=March 2013 |publisher=[[CERN]] |website=home.web.cern.ch |access-date=20 September 2013}}</ref>

In a speculative case where the [[Higgs mechanism|electroweak symmetry breaking]] [[Electroweak scale|scale]] were lowered, the unbroken {{math|SU(2)}} interaction would eventually become [[Color confinement|confining]]. Alternative models where {{math|SU(2)}} becomes confining above that scale appear quantitatively similar to the [[Standard Model]] at lower energies, but dramatically different above symmetry breaking.<ref>{{cite journal |last1=Claudson |first1=M. |last2=Farhi |first2=E. |last3=Jaffe |first3=R. L. |title=Strongly coupled standard model |journal=Physical Review D |date=1 August 1986 |volume=34 |issue=3 |pages=873–887 |doi=10.1103/PhysRevD.34.873 |pmid=9957220 |bibcode=1986PhRvD..34..873C }}</ref>