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The Higgs boson

The origins of the Brout-Englert-Higgs mechanism

In the 1970s, physicists realized that there are very close ties between two of the four fundamental forces – the weak force and the electromagnetic force. The two forces can be described within the same theory, which forms the basis of the Standard Model. This “unification” implies that electricity, magnetism, light and some types of radioactivity are all manifestations of a single underlying force known as the electroweak force.

The basic equations of the unified theory correctly describe the electroweak force and its associated force-carrying particles, namely the photon, and the W and Z bosons, except for a major glitch. All of these particles emerge without a mass. While this is true for the photon, we know that the W and Z have mass, nearly 100 times that of a proton. Fortunately, theorists Robert Brout, François Englert and Peter Higgs made a proposal that was to solve this problem. What we now call the Brout-Englert-Higgs mechanism gives a mass to the W and Z when they interact with an invisible field, now called the “Higgs field”, which pervades the universe.

Just after the big bang, the Higgs field was zero, but as the universe cooled and the temperature fell below a critical value, the field grew spontaneously so that any particle interacting with it acquired a mass. The more a particle interacts with this field, the heavier it is. Particles like the photon that do not interact with it are left with no mass at all. Like all fundamental fields, the Higgs field has an associated particle – the Higgs boson. The Higgs boson is the visible manifestation of the Higgs field, rather like a wave at the surface of the sea.

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Featured updates on this topic

28 Aug 2018 – The ATLAS and CMS experiments have finally observed the Higgs boson decaying to bottom quarks

4 Jun 2018 – New results from CMS and ATLAS experiments reveal how strongly the Higgs boson interacts with the heaviest known elementary particle, the top quark

Updates

7 Sep 2018 – ATLAS searches for vector-like top quarks that could explain the Higgs boson’s small mass

4 Jul 2018 – It is six years ago that the discovery of the Higgs boson was announced, to great fanfare in the world’s media, as a crowning success of CERN’s LHC

19 Mar 2018 – ATLAS and CMS present new measurements of the properties of the Higgs boson

18 Jan 2018 – The CMS collaboration closes in on exotic long-lived particles that could get trapped in its detector layers

20 Nov 2017 – Steven Weinberg’s iconic paper, A Model of Leptons, was published in 1967 and determined the direction for high-energy particle physics research

10 Aug 2017 – With the LHC now back smashing protons together at an energy of 13 TeV, what exotic beasts do physicists hope to find?

4 Jul 2017 – Five years ago, the ATLAS and CMS collaborations announced the discovery of the Higgs boson

5 Jul 2016 – To celebrate the fourth birthday of the Higgs boson announcement CERN invites you to make your own particle-based pizza

4 Jul 2016 – A new citizen science project gives sofa-scientists the chance to search for previously undiscovered particles

18 May 2016 – Do recent discoveries mean there’s nothing left? Find out what the future holds for theoretical physics in our final In Theory series installment