Nobel Prize in Physics 2013: The Higgs Mechanism and the Higgs Particle

This note covers the Nobel Prize in Physics 2013: who won it, what the Higgs mechanism is and why particles have mass, how the theory was confirmed at CERN's Large Hadron Collider, how the discovery unfolded across five decades, why it matters for physics today, and a quick-facts summary for exams.

What was the Nobel Prize in Physics 2013 awarded for?

The Royal Swedish Academy of Sciences gave the award jointly to François Englert and Peter Higgs

"for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider"

In plain words: Englert and Higgs worked out, in 1964, a mathematical trick that lets particles in a theory have mass without wrecking the symmetry the theory depends on.

Their idea relies on an invisible field that fills all of space. Particles that interact with this field gain mass; particles that ignore it stay massless.

In 2012, two giant experiments at CERN found the particle this theory predicted, nicknamed the Higgs particle, and that discovery is what finally confirmed the 1964 theory and triggered the prize.

The official name of the award is the Nobel Prize in Physics.

Who are the laureates?

François Englert

François Englert was born on 6 November 1932 in Etterbeek, Belgium. At the time of the award he was affiliated with the Université Libre de Bruxelles in Brussels, Belgium, where he was Professor Emeritus.

He received one half of the prize. During the German occupation of Belgium in the Second World War, Englert hid his Jewish origins and stayed at different orphanages.

He trained first as an electrical-mechanical engineer and earned his physics PhD from the Université Libre de Bruxelles in 1959, later spending two years at Cornell University before returning to Brussels.

Working with his colleague Robert Brout, who died before the prize was announced, Englert proposed in 1964 the mechanism by which particles acquire mass. He died on 18 June 2026 in Uccle, Belgium.

Peter Higgs

Peter W. Higgs was born on 29 May 1929 in Newcastle upon Tyne, United Kingdom. At the time of the award he was affiliated with the University of Edinburgh in the United Kingdom, as Professor Emeritus.

He received one half of the prize. Higgs suffered from asthma as a child and was partly home-schooled in Bristol before moving to London at 17 to study maths and physics.

He completed his PhD at King's College, University of London, in 1954, then moved to Edinburgh, where he spent most of his career.

Independently of Englert and Brout, Higgs worked out the same mass-generating mechanism in 1964 and went further by explicitly writing down an expression for the mass of the new particle that the mechanism implies, even though the theory itself could not predict its numerical value, which is why the particle later came to be called the Higgs particle. He died on 8 April 2024 in Edinburgh, Scotland.

What problem were Englert and Higgs trying to solve?

By the early 1960s physicists had a very successful theory for how charged particles interact through light, called quantum electrodynamics. It described the electromagnetic force, carried by massless photons, with great precision.

Physicists wanted similar theories, called gauge theories, for the other two forces that act inside the nucleus: the strong force and the weak force.

The trouble was that the weak force is carried by particles that must be heavy (what became known as the W and Z particles), while the clean mathematics of a gauge theory, as the popular information page explained, normally demands that the force-carrying particles be massless, like the photon.

If physicists simply inserted mass by hand, the theory's equations stopped making consistent sense. The Standard Model of particle physics, which aims to describe matter particles such as electrons and quarks together with the forces between them, was threatened at its foundation by this clash.

A deeper feature was at stake too: the Standard Model's equations have a built-in symmetry, in the same way that a ball looks identical from any angle.

According to the scientific background paper, a mathematical result called Goldstone's theorem seemed to say that spontaneously breaking such a symmetry should always produce an unwanted new massless particle, for which there was no experimental evidence.

Finding a way around this obstacle, while still giving the W and Z particles their mass, was the open problem that Englert, Brout and Higgs tackled in 1964.

How does the Higgs mechanism give particles mass?

The core idea, as the popular information page describes it, is that space is not truly empty. It is filled everywhere by an invisible field, now called the Higgs field, which does not switch off even in a vacuum.

Particles acquire mass by interacting with this field: particles that interact strongly with it become heavy, particles that interact weakly become light, and particles that do not interact with it at all, such as the photon, stay massless.

A useful picture used in the popular explanation is the bowl and the Mexican hat. Early on, the Higgs field's lowest-energy point sat exactly at the centre of a symmetric bowl, like a ball resting at the bottom.

If a hump then grows at the centre of that bowl, turning it into the shape of a sombrero, the centre point stays symmetrical but becomes unstable, and the ball rolls away to settle at some point around the rim, away from the centre.

The field has moved to a new stable level that is not at the symmetric middle: the underlying symmetry is still present in the equations, but it is hidden from view once the ball has rolled downhill. Physicists call this spontaneous symmetry breaking.

1. Start with a theory whose equations are symmetric, including a field that could in principle sit at a single, symmetric minimum.
2. Arrange, as Englert, Brout and Higgs did, for that minimum to shift away from the symmetric point, so the field settles into a non-zero value everywhere in space, the vacuum expectation value.
3. Because the field no longer sits at zero, the force-carrying particles that interact with it, the W and Z particles, pick up mass from that interaction, while the symmetry of the underlying equations is preserved, only hidden.
4. Three of the four possible disturbances of the field get absorbed into the W and Z particles, giving them their mass and extra directions of motion; one disturbance survives as an independent, massive particle: the Higgs particle itself.

Draw a bowl-shaped curve with a bump raised in its centre, so the cross-section looks like a hat with a brim.

Mark the unstable symmetric point at the centre top, and mark a stable point partway down the brim where a ball has rolled to rest, showing that the field's lowest-energy value has moved away from the symmetric centre.

Both routes to the same physics, Englert and Brout's paper and Higgs's first paper, were submitted about a month apart, in the summer of 1964.

The scientific background paper records that Englert worked with his colleague Robert Brout, who had died before the prize was announced, while Higgs worked alone and was the one who explicitly worked out the mass of the leftover scalar particle, which is why that particle is commonly called the Higgs particle even though the mechanism as a whole is shared.

How was the Higgs particle actually found?

Confirming a 1964 theory required building a machine that could recreate, for a fleeting instant, conditions dense enough in energy to produce a very heavy, short-lived particle.

That machine is the Large Hadron Collider (LHC) at CERN, the European particle-physics laboratory outside Geneva, Switzerland, described by the committee as "probably the largest and the most complex machine ever constructed by humans".

Protons were injected into the ring every ten hours, travelling in opposite directions around the tunnel, and smashed into each other at the four interaction points.

Each useful collision released a burst of roughly a thousand particles, out of which the Higgs particle, at an eventual measured mass of about 125 GeV, more than 100 times the mass of a proton, appeared only very rarely, which is part of why it took so long and so many collisions to find it.

On 4 July 2012, CERN announced that both the ATLAS and CMS teams had independently seen a new particle matching the properties expected of the Higgs particle, mainly by observing it decaying into two photons or into four leptons.

Englert and Higgs were both present in the audience that day. The scientific background paper notes that the finding was made "with significance at the level of five standard deviations," meaning the chance that it was a random fluctuation in the background data was extremely small.

How did the discovery unfold?

Why does this discovery matter?

The Higgs particle was, in the committee's words, "the missing piece in the Standard Model puzzle", the theory that describes almost everything physicists know about how matter and forces fit together.

Confirming its existence showed that the 1964 mechanism Englert and Higgs proposed is the way Nature actually generates mass for the W and Z particles, and for other particles that interact with the Higgs field.

But the discovery did not close the book on physics. The press release points out two open problems the Standard Model still cannot explain.

First, the model treats neutrinos as essentially massless, while studies show they do in fact have a small mass.

Second, the visible matter the Standard Model describes accounts for only about one fifth of all the matter in the universe; the rest is dark matter, of a kind not yet identified, known mainly through its gravitational pull on galaxies.

Scientists at CERN continue to search the LHC's particle collisions for clues to these unanswered questions, including whether the Higgs particle itself has any hidden connection to dark matter.

How does this connect to what you study?

In school physics, you meet the idea that mass is a measure of how much an object resists a push, and that forces act between objects.

The Higgs mechanism takes this further: it explains, at the level of fundamental particles, where that resistance to being pushed, that mass, actually comes from in the first place.

The same chapters that introduce atoms being made of electrons, protons and neutrons connect upward to this story, since protons and neutrons are themselves built from quarks, and both quarks and electrons get their mass from interacting with the Higgs field.

The idea of symmetry in physical laws, familiar from simple examples such as a ball looking the same from any angle, also appears here in a much deeper form: the mathematics behind forces and particle masses depends on symmetries that can be hidden, or "spontaneously broken," without actually disappearing from the underlying equations.

Quick facts for exams

The Nobel Prize in Physics 2013 was awarded jointly to François Englert (Belgium) and Peter Higgs (United Kingdom) for the theoretical discovery of the mechanism by which subatomic particles acquire mass, a mechanism confirmed through the 2012 discovery of the Higgs particle by the ATLAS and CMS experiments at CERN's Large Hadron Collider.

The award was announced on 8 October 2013 by the Royal Swedish Academy of Sciences, with each laureate receiving one half of the 8,000,000 Swedish kronor prize. Englert proposed the idea with his colleague Robert Brout in 1964;

Higgs proposed it independently the same year and also worked out an explicit expression for the mass of the resulting particle, though the theory could not predict its numerical value.

Note: Source. The prize facts in this note are from the Nobel Prize's official site, nobelprize.org.

Glossary

• Standard Model — the theory describing the known fundamental matter particles and the forces, except gravity, that act between them.
• Higgs field — an invisible field that the theory says fills all of space and does not switch off even in a vacuum.
• Higgs particle (Higgs boson) — the particle predicted to exist as a vibration of the Higgs field, discovered at CERN in 2012.
• Spontaneous symmetry breaking — a process in which a theory's equations stay symmetric but the system settles into a state that is not symmetric.
• Gauge theory — a type of theory, such as electromagnetism, built from a symmetry that is preserved even when certain quantities are changed locally.
• W and Z particles — the massive particles that carry the weak force, which causes radioactive decay.
• Quark — one of the small particles that make up protons and neutrons inside an atomic nucleus.
• Dark matter — an unidentified kind of matter, detected through its gravitational pull, that makes up most of the matter in the universe.
• Large Hadron Collider (LHC) — CERN's 27 kilometre circular particle accelerator used to collide protons at very high energy.
• ATLAS and CMS — the two independent experimental teams at the LHC, each of about 3,000 scientists, that detected the Higgs particle.
• Electroweak force — the unified description of the electromagnetic force and the weak force at high energy.
• Vacuum expectation value — the non-zero value the Higgs field settles into everywhere in space, even in a vacuum.
• Renormalisable theory — a quantum field theory in which only a limited number of quantities need adjusting to get finite, sensible predictions.
• TeV (teraelectronvolt) — a unit of energy equal to a thousand billion electronvolts, used to describe particle collision energies.

Common errors and misconceptions

• Misconception: The Higgs particle itself causes all mass directly, like a substance stuck onto particles. Correct: Mass comes from a particle's interaction with the surrounding Higgs field; the Higgs particle is a separate, detectable vibration of that same field.
• Misconception: Peter Higgs discovered the Higgs mechanism alone. Correct: François Englert, working with Robert Brout, proposed essentially the same mechanism independently and at the same time, in 1964.
• Misconception: The Higgs particle was found the same year the prize was given. Correct: It was found on 4 July 2012, and the prize was announced over a year later, on 8 October 2013.
• Misconception: The Standard Model, now that the Higgs particle is found, explains everything in physics. Correct: It still treats neutrinos as essentially massless, even though they are known to have a small mass, and it does not explain dark matter, which makes up most of the matter in the universe.
• Misconception: The Large Hadron Collider is a simple straight-line machine. Correct: It is a 27 kilometre circular underground tunnel where beams of protons travel in opposite directions and collide at several points.
• Misconception: Every particle gets mass from the Higgs field in the same amount. Correct: Particles that interact weakly with the field become light, those that interact strongly become heavy, and some, like the photon, stay massless.
• Misconception: The prize was awarded only for the theoretical idea. Correct: The citation explicitly credits the theory and its experimental confirmation by the ATLAS and CMS experiments.

Exam-style questions with model answers

Q1. In which year was the Nobel Prize in Physics 2013 announced? [1 mark]

1. It was announced on 8 October 2013.

Q2. Name the two laureates of the Nobel Prize in Physics 2013. [2 marks]

1. The prize went jointly to François Englert of Belgium and Peter Higgs of the United Kingdom, who each received one half of the award for their theoretical work on how particles acquire mass.

Q3. State the official citation for the Nobel Prize in Physics 2013. [3 marks]

1. The citation reads: "for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider." It credits both the 1964 theory and its 2012 experimental confirmation.

Q4. Explain, in your own words, how the Higgs field is supposed to give particles mass. [4 marks]

1. According to the theory, space is filled everywhere by an invisible Higgs field that never switches off, even in a vacuum. Particles gain mass by interacting with this field: those that interact strongly become heavy, those that interact weakly become light, and particles such as the photon, which do not interact with it at all, stay massless. The field's own lowest-energy state shifted away from the symmetric centre of its potential early in the universe's history, a process called spontaneous symmetry breaking, and it is this shift that lets the W and Z force-carrying particles acquire mass while keeping the underlying equations of the theory symmetric.

Q5. Describe how the Large Hadron Collider was used to confirm the Higgs mechanism. [5 marks]

1. The Large Hadron Collider is a 27 kilometre circular accelerator at CERN, built about 100 metres underground, in which beams of protons travelling at 99.99999 per cent of the speed of light are made to collide head on at several points, up to 40 million times per second. Two independent teams of about 3,000 scientists each, called ATLAS and CMS, built huge detectors to sift through the billions of collisions for signs of a new, very heavy particle. Each useful collision produced a burst of roughly a thousand particles, among which the predicted Higgs particle, at about 125 GeV, appeared only extremely rarely, mainly showing up as decays into two photons or into four leptons. On 4 July 2012, both teams independently announced they had found a particle matching the predicted properties, with a statistical significance high enough that the chance of a background fluctuation was judged extremely small, confirming the 1964 theory of Englert and Higgs.

Q6. Why is the discovery still considered incomplete by physicists, according to the Nobel committee's own statement? [3 marks]

1. The committee noted that the Standard Model, even with the Higgs particle confirmed, treats neutrinos as nearly massless although they are known to have mass, and that it only describes visible matter, which accounts for about one fifth of all matter in the universe, leaving the nature of dark matter unexplained.

Q7. Who worked with François Englert on the original 1964 theory, and what happened to that collaborator? [2 marks]

1. Englert worked with his colleague Robert Brout, who had died before the Nobel Prize was announced in 2013 and so could not share in the award.

Key takeaways

• The Nobel Prize in Physics 2013 honoured François Englert and Peter Higgs for explaining how subatomic particles get mass.
• Their 1964 theory proposes an invisible Higgs field filling all space, whose interaction with particles gives them mass.
• The mechanism allowed the weak force's carrier particles to be massive while keeping the theory's symmetry intact, just hidden.
• CERN's ATLAS and CMS experiments confirmed the predicted Higgs particle on 4 July 2012.
• The Large Hadron Collider, a 27 kilometre underground accelerator, made the discovery possible.
• The Standard Model, now completed by the Higgs particle, still treats neutrinos as massless and cannot explain dark matter.
• Robert Brout, Englert's collaborator, died before the prize could be shared with him.
• The prize was announced on 8 October 2013, with each laureate receiving one half of the award.

Test yourself

Where was Peter Higgs affiliated at the time of the award?

Peter Higgs was affiliated with the University of Edinburgh in the United Kingdom when the prize was awarded in 2013.

What date was the Higgs particle discovery announced at CERN?

CERN announced the discovery on 4 July 2012, after both the ATLAS and CMS experiments found a matching new particle.

What keeps the photon massless according to the theory?

The photon does not interact with the Higgs field at all, so it gains no mass and travels at the speed of light.

How much of the universe's matter does the Standard Model actually describe?

The Standard Model describes only visible matter, which the committee said accounts for about one fifth of all matter in the universe.

What shape is used to picture spontaneous symmetry breaking in the popular explanation?

The popular explanation uses a bowl that develops a central hump, becoming shaped like a Mexican hat, with the ball rolling away from the unstable centre.

How large is the Large Hadron Collider's tunnel?

The Large Hadron Collider sits in a circular tunnel that is 27 kilometres long, located about 100 metres underground at CERN.

Who submitted the first paper proposing the mass-generating mechanism, and when?

François Englert, working with Robert Brout, submitted the first paper in 1964, shortly before Peter Higgs submitted his own independent papers.