Sunday, October 6, 2013


The Higgs boson or Higgs particle is an elementary particle believed to exist in the Standard Model of physics. It may have finally been detected in July 2012, almost 50 years after being predicted, but it will take further testing to be certain. Its discovery, or confirmation of its existence, would be monumental because it would finally prove the existence of the Higgs field, the simplest and longest standing explanation of why some fundamental particles have mass when 'naive' theory says they should be massless, and - linked to this - why the weak force has a very short range while the electromagnetic force has an unlimited range. Its discovery would profoundly influence human understanding of the universe, validate the final unconfirmed part of the Standard Model, guide other theories and discoveries in particle physics, and – as with other fundamental discoveries of the past – potentially over time lead to developments in "new" physics, new technology, and enhancements to society.
This unanswered question in fundamental physics is of such importance that it led to a decades-long search for the Higgs boson and finally the construction of one of the most expensive and complex experimental facilities to date, the Large Hadron Collider
See full size image able to create and study Higgs bosons and related questions. On 4 July 2012, two separate experimental teams at the Large Hadron Collider announced that they had each independently confirmed the existence of a previously unknown boson of mass between 125 and 127 GeV/c2 which physicists suspected eventually will be agreed to be a Higgs boson, and whose known behaviour (up to December 2012) closely matches a Standard Model Higgs boson.
The Higgs boson is named after Peter Higgs, who—along with Brout and Englert, and with Guralnik, Hagen, and Kibble ("GHK")—proposed the mechanism that suggested such a particle in 1964. Higgs was the only one who emphasised the existence of the particle and calculated some of its properties. Although Higgs' name has become ubiquitous in this theory, the resulting electroweak model (the final outcome) involved several researchers between about 1960 and 1972, who each independently developed different parts. In mainstream media the Higgs boson is often referred to as the "God particle," from a 1993 book on the topic; the sobriquet is strongly disliked by many physicists, who regard it as inappropriate sensationalism.
In the Standard Model, the Higgs particle is a boson with no spin, electric charge, or color charge. It is also very unstable, decaying into other particles almost immediately. The Higgs particle is a quantum excitation of one component of the four component Higgs field, a scalar field with two neutral and two electrically charged components, forming a complex doublet of the weak isospin SU(2) symmetry, and with U(1) weak hypercharge of +½ (or +1 depending on convention). The field has a "Mexican hat" shaped potential and takes on a nonzero strength everywhere (including otherwise empty space) which breaks the weak isospin symmetry in its vacuum state. When this happens, three of the four Higgs field components are "absorbed" by the originally massless SU(2) and U(1) gauge bosons (the "Higgs mechanism") to become the longitudinal components of the now-massive W and Z bosons. The fourth electrically neutral component separately couples to other particles known as fermions (via Yukawa couplings), causing these to acquire mass as well. The fourth component's quantum excitations manifest as the Higgs boson. Some versions of the theory predict more than one kind of Higgs fields and bosons. Alternative "Higgsless" models would be considered if the Higgs boson is not discovered.

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