A prototypical effective ‘Mexican hat’ potential that leads to ‘spontaneous’ symmetry breaking. The vacuum, i.e., the lowest-energy state, is described by a randomly-chosen point around the bottom of the brim of the hat. In a ‘global’ symmetry, movements around the bottom of the hat corresponds to a massless spin-zero ‘Nambu-Goldstone’ boson. In the case of a local (gauge) symmetry, as was pointed out by Englert and Brout, by Higgs and by Guralnik, Hagen and Kibble, this boson combines with a massless spin one boson to yield a massive spin-one particle. The Higgs boson is a massive spin-zero particle corresponding to quantum fluctuations in the radial direction, oscillating between the centre and the side of the hat.
John Ellis, Mary K. Gaillard, Dimitri V. Nanopoulos
The Higgs boson was postulated in 1964, and phenomenological studies of its possible production and decays started in the early 1970s, followed by studies of its possible production in e+ e-, pbar p and pp collisions, in particular.
Until recently, the most sensitive searches for the Higgs boson were at LEP between 1989 and 2000, which have been complemented by searches at the Fermilab Tevatron.
The LHC has recently entered the hunt, excluding a Higgs boson over a large range of masses and revealing a tantalizing hint in the range 119 to 125 GeV, and there are good prospects that the existence or otherwise of the Higgs boson will soon be established. One of the most attractive possibilities is that the Higgs boson is accompanied by supersymmetry, though composite options have yet to be excluded.
This article reviews some of the key historical developments in Higgs physics over the past half-century.
Read more: http://arxiv.org/pdf
Posted on January 31, 2012
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