Topic

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.

Featured updates on this topic

19 Dec 2013 – Higgs boson decays, a Nobel prize for Higgs and Englert and a huge Open Days event were among the big stories at CERN this year

27 Nov 2013 – The ATLAS experiment at CERN has found evidence for the Higgs boson decaying to two tau particles

8 Oct 2013 – The 2013 Nobel prize in physics has been awarded to François Englert and Peter Higgs for their theoretical work on the Higgs boson

7 May 2013 – Physicists from the ATLAS and CMS collaborations explain how they came to identify the new particle of 2012 as "a Higgs boson"

14 Mar 2013 – With two and a half times more data analysed than in July last year, ATLAS and CMS find that the new particle looks more and more like a Higgs boson

Updates

7 Jul 2014 – At ICHEP in Valencia, Spain, all four LHC experiments presented new results from the LHC’s first run. Run 2 physics holds much promise

23 Jun 2014 – Results reported by ATLAS and CMS discuss the decay of Higgs bosons directly to fermions, the particles that make up matter

19 May 2014 – Teach the machines: CERN launches competition to develop machine-learning analysis techniques for Higgs data

31 Mar 2014 – At the Moriond conference CMS presented the best constraint yet of the Higgs boson “width”, a parameter that determines the particle’s lifetime

10 Mar 2014 – On his first trip to CERN since sharing the Nobel prize in physics last year with Peter Higgs, François Englert talks Higgs bosons and supersymmetry

26 Feb 2014 – Watch François Englert explain the equations for the Brout-Englert-Higgs mechanism that gives particles mass, with the help of a blackboard

3 Dec 2013 – The CMS collaboration have measured the decay of the Higgs boson to pairs of bottom quarks and to pairs of tau leptons

25 Oct 2013 – CERN, along with Peter Higgs and François Englert, today receives the Prince of Asturias Award during a ceremony in Spain

9 Oct 2013 – Cameras were rolling in CERN's building 40 when members of the ATLAS and CMS collaborations heard the news from Stockholm live yesterday

4 Jul 2013 – In the first year after the discovery of the Higgs boson, physicists from ATLAS and CMS have been busy studying the properties of the new particle