Search for the Higgs boson

The search for the Higgs boson was a 40-year effort by physicists to prove the existence or non-existence of the Higgs boson, first theorised in the 1960s. The Higgs boson was the last unobserved fundamental particle in the Standard Model of particle physics, and its discovery was described as being the "ultimate verification" of the Standard Model. In March 2013, the Higgs boson was officially confirmed to exist.

One confirmed answer would additionally prove or disprove the existence of the hypothetical Higgs field—a field of immense significance that is hypothesised as the source of electroweak symmetry breaking and the means by which elementary particles acquire mass. Symmetry breaking is considered proven but confirming exactly how this occurs in nature is a major unanswered question in physics. Proof of the Higgs field (by observing the associated particle), and evidence of its properties, is 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. If the Higgs boson were shown not to exist, other alternative sources for the Higgs mechanism would need to be considered and the same experimental equipment would be used for that purpose.

Despite their importance, the search and any proof have been extremely difficult and taken decades, because direct production, detection and verification of the Higgs boson on the scale needed to confirm the discovery and learn its properties requires a very large experimental project and huge computing resources. For this reason, most experiments until around 2011 aimed to exclude ranges of masses that the Higgs could not have. Ultimately the search led to the construction of the Large Hadron Collider (LHC) in Geneva, Switzerland, the largest particle accelerator in the world, designed especially for this and other high-energy tests of the Standard Model.

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