Editing Zero-point energy (section)

=== Higgs field ===
{{Main|Higgs mechanism}}

[[File:Mecanismo de Higgs PH.png|thumb|The potential for the Higgs field, plotted as function of {{math|''ϕ''<sup>0</sup>}} and {{math|''ϕ''<sup>3</sup>}}. It has a ''Mexican-hat'' or ''champagne-bottle profile'' at the ground.]]
The Standard Model hypothesises a field called the Higgs field (symbol: {{mvar|ϕ}}), which has the unusual property of a non-zero amplitude in its ground state (zero-point) energy after renormalization; i.e., a non-zero vacuum expectation value. It can have this effect because of its unusual "Mexican hat" shaped potential whose lowest "point" is not at its "centre". Below a certain extremely high energy level the existence of this non-zero vacuum expectation [[Spontaneous symmetry breaking|spontaneously breaks]] [[electroweak]] [[gauge symmetry]] which in turn gives rise to the Higgs mechanism and triggers the acquisition of mass by those particles interacting with the field. The Higgs mechanism occurs whenever a charged field has a vacuum expectation value. This effect occurs because scalar field components of the Higgs field are "absorbed" by the massive bosons as degrees of freedom, and couple to the fermions via Yukawa coupling, thereby producing the expected mass terms. The expectation value of {{math|''ϕ''<sup>0</sup>}} in the ground state (the vacuum expectation value or VEV) is then {{math|⟨''ϕ''<sup>0</sup>⟩ {{=}} {{sfrac|''v''|{{sqrt|2}}}}}}, where {{math|''v'' {{=}} {{sfrac|{{abs|''μ''}}|{{sqrt|''λ''}}}}}}. The measured value of this parameter is approximately {{val|246|u=GeV/c2}}.<ref name="PDGreview2012">
{{cite web
 |title=Higgs bosons: theory and searches
 |url=http://pdg.lbl.gov/2012/reviews/rpp2012-rev-higgs-boson.pdf
 |website=PDGLive
 |publisher=Particle Data Group
 |date=12 July 2012
 |access-date=15 August 2012
}}</ref> It has units of mass, and is the only free parameter of the Standard Model that is not a dimensionless number.

The Higgs mechanism is a type of [[superconductivity]] which occurs in the vacuum. It occurs when all of space is filled with a sea of particles which are charged and thus the field has a nonzero vacuum expectation value. Interaction with the vacuum energy filling the space prevents certain forces from propagating over long distances (as it does in a superconducting medium; e.g., in the [[Ginzburg–Landau theory]]).