Science · Physics

The Higgs boson

Predicted 1964; discovered 2012

Physics — particle physics

The Higgs boson is the quantum of the Higgs field, the all-pervading field that gives mass to the elementary particles. It was predicted in 1964 by three independent groups — Robert Brout and François Englert; Peter Higgs; and Gerald Guralnik, C. R. Hagen and Tom Kibble — as a by-product of the mechanism that lets the W and Z bosons of the weak force be heavy while the photon stays massless. Finding it was the headline job of the Large Hadron Collider, and on 4 July 2012 the ATLAS and CMS experiments at CERN announced a new particle of about 125 GeV that matched. It is the only fundamental scalar particle known: spin zero, no electric charge, no colour charge. Englert and Higgs shared the 2013 Nobel Prize in Physics; Brout had died in 2011.

How to spot them

▸The only elementary particle with spin zero — the Standard Model's one fundamental scalar
▸Announced at CERN on 4 July 2012 by two experiments at once, to a standing ovation
▸Nicknamed 'the God particle' by a book title its author never wanted
▸Its field is what makes the W and Z heavy while the photon stays massless
▸Its discovery completed the Standard Model and won the 2013 Nobel Prize in Physics

Key facts

The particle whose discovery on 4 July 2012 was announced in a Comic Sans slide at CERN (2012)

The CMS presentation's typeface became almost as famous as the result.

The 'God particle' of Leon Lederman's 1993 book (1993)

Lederman said he wanted a ruder title; his publisher would not have it.

The quantum of the field that gives the W and Z their mass

Without it the electroweak symmetry stays unbroken and the weak force has infinite range.

Spin 0, charge 0, mass about 125 GeV — the Standard Model's only fundamental scalar

Every other elementary particle is a spin-1/2 fermion or a spin-1 (or spin-2) boson.

The subject of a 1964 paper rejected by Physics Letters as 'of no obvious relevance to physics' (1964)

The Edinburgh theorist added a paragraph about a new massive particle and published elsewhere.

Found by ATLAS and CMS in its decays to two photons and to four leptons (2012)

Both channels give a sharp mass peak, which is why they led the discovery.

Key ideas

The Higgs field has a non-zero value everywhere, even in empty space; particles that interact with it strongly behave as though heavy, and those that ignore it, like the photon, stay massless.
The mechanism is spontaneous symmetry breaking: the laws stay symmetric but the vacuum picks a direction, like a pencil balanced on its point falling one way.
Only about 1% of the mass of ordinary matter comes from the Higgs field; the rest is the binding energy of quarks and gluons inside protons and neutrons.

Quick-fire facts

•Named after Peter Higgs (1929–2024), the Edinburgh physicist whose 1964 paper explicitly predicted a new massive particle
•The mechanism is more fairly called the Brout–Englert–Higgs mechanism; six physicists published it in 1964
•Announced at CERN on 4 July 2012; Peter Higgs was in the audience and was seen wiping his eyes
•Mass about 125 GeV/c², roughly 133 times the mass of a proton
•The 2013 Nobel Prize in Physics went to François Englert and Peter Higgs; Robert Brout had died in 2011
•Leon Lederman's nickname 'the God particle' came from a 1993 book; he had wanted 'the Goddamn Particle' for how hard it was to find
•David Miller won a UK science-minister competition by explaining the Higgs field as a crowded cocktail party that clusters around a celebrity
•It lives about 10⁻²² seconds; it is never seen directly, only inferred from its decay products
•Higgs was famously hard to reach: he had no mobile phone or email, and learned of his Nobel from a neighbour in the street

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Sources

CERN — The Higgs boson
The Nobel Foundation — The Nobel Prize in Physics 2013