The Higgs boson or Higgs particle is an elementary particle initially theorised in 1964, and tentatively confirmed to exist on 14 March 2013. The discovery has been called “monumental” because it appears to confirm the existence of the Higgs field, which is pivotal to the Standard Model and other theories within particle physics. It would explain why some fundamental particles have mass when the symmetries controlling their interactions should require them to be massless, and—linked to this—why the weak force has a much shorter range than the electromagnetic force. Its existence and knowledge of its exact properties are expected to impact scientific knowledge across a range of fields. It should allow physicists to finally validate the last untested area of the Standard Model’s approach to fundamental particles and forces, guide other theories and discoveries in particle physics, and—as with other fundamental discoveries of the past—potentially over time lead to developments in “new” physics, and new technologies.
This unanswered question in fundamental physics is of such importance that it led to a search of more than 40 years for the Higgs boson and finally the construction of one of the world’s most expensive and complex experimental facilities to date, the Large Hadron Collider, able to create Higgs bosons and other particles for observation and study. On 4 July 2012, it was announced that a previously unknown particle with a mass between 125 and 127 GeV/c2 (134.2 and 136.3 amu) had been detected; physicists suspected at the time that it was the Higgs boson. By March 2013, the particle had been proven to behave, interact and decay in many of the ways predicted by the Standard Model, and was also tentatively confirmed to have + parity and zero spin, two fundamental attributes of a Higgs boson–making it also the first known scalar particle to be discovered in nature,–although a number of other properties were not fully proven, and some partial results do not yet precisely match those expected, and some data are still being awaited or analyzed. As of March 2013, it was still uncertain whether its properties (when eventually known) will exactly match the predictions of the Standard Model, or whether, as predicted by some theories, multiple Higgs bosons exist.
The Higgs boson is named after Peter Higgs, one of six physicists who, in 1964, proposed the mechanism that suggested the existence of such particle. Although Higgs’s name has come to be associated with this theory, several researchers between about 1960 and 1972 each independently developed different parts of it. In mainstream media the Higgs boson has often been called the “God particle,” from a 1993 book on the topic; the nickname is strongly disliked by many physicists, including Higgs, who regard it as inappropriate sensationalism.
In the Standard Model, the Higgs particle is a boson with no spin, electric charge, or color charge. It is also very unstable, decaying into other particles almost immediately. It is a quantum excitation of one of the four components of the Higgs field, constituting a scalar field, with two neutral and two electrically charged components, and forms a complex doublet of the weak isospin SU(2) symmetry. The field has a “Mexican hat” shaped potential with nonzero strength everywhere (including otherwise empty space) which in its vacuum state breaks the weak isospin symmetry of the electroweak interaction. When this happens, three components of the Higgs field are “absorbed” by the SU(2) and U(1) gauge bosons (the “Higgs mechanism”) to become the longitudinal components of the now-massive W and Z bosons of the weak force. The remaining electrically neutral component separately couples to other particles known as fermions (via Yukawa couplings), causing these to acquire mass as well. Some versions of the theory predict more than one kind of Higgs fields and bosons. Alternative “Higgsless” models would have been considered if the Higgs boson were not discovered.
What is the God particle?
The term ‘The God particle’ was coined by the physicist Leon Lederman in his 1993 popular science book, The God Particle: If the Universe Is the Answer, What Is the Question? The particle that the book title refers to is the ‘Higgs boson’.
The particle we now call the Higgs boson has never been observed. First hypothesised in 1964, the Higgs boson, if discovered, would be a vital missing piece of the model that physicists use to describe elementary particles and their interactions: the Standard Model.
What is the Higgs boson?
The Standard Model of particle physics lays out the basics of how elementary particles and forces interact in the universe. But the theory crucially fails to explain how particles actually get their mass.
Particles, or bits of matter, range in size and can be larger or smaller than atoms. Electrons, protons and neutrons, for instance, are the subatomic particles that make up an atom.
Scientists believe that the Higgs boson is the particle that gives all matter its mass.
Experts know that elementary particles like quarks and electrons are the foundation upon which all matter in the universe is built. They believe the elusive Higgs boson gives the particles mass and fills in one of the key holes in modern physics.
How does the Higgs boson work?
The Higgs boson is part of a theory first proposed by Higgs and others in the 1960s to explain how particles obtain mass.
The theory proposes that a so-called Higgs energy field exists everywhere in the universe. As particles zoom around in this field, they interact with and attract Higgs bosons, which cluster around the particles in varying numbers.
Imagine the universe like a party. Relatively unknown guests at the party can pass quickly through the room unnoticed; more popular guests will attract groups of people (the Higgs bosons) who will then slow their movement through the room.
The speed of particles moving through the Higgs field works much in the same way. Certain particles will attract larger clusters of Higgs bosons — and the more Higgs bosons a particle attracts, the greater its mass will be.
What does the Higgs boson have to do with God?
The Higgs boson has nothing to do with God. It was simply a snappy term to illustrate the ubiquitous effect of the Higgs field, and its importance in determining mass.
Why is finding the Higgs boson so important?
While finding the Higgs boson won’t tell us everything we need to know about how the universe works, it will fill in a huge hole in the Standard Model that has existed for more than 50 years, according to experts.
How are scientists searching for the Higgs boson?
For the past 18 months scientists have searched for the Higgs boson by smashing protons together at high energy in the $10 billion Large Hadron Collider (LHC) at CERN in Geneva, Switzerland.
Inside the LHC, which is located 328 feet underground in a 17-mile tunnel and is the most powerful particle accelerator ever built, high speed proton collisions generate a range of even smaller particles that scientists sift through in search of a signal in the data suggesting the existence of the Higgs boson.
Recognition and awards:
There has been considerable discussion of how to allocate the credit if the Higgs boson is proven, made more pointed as a Nobel prize had been expected, and the very wide basis of people entitled to consideration. These include a range of theoreticians who made the Higgs mechanism theory possible, the theoreticians of the 1964 PRL papers (including Higgs himself), the theoreticians who derived from these, a working electroweak theory and the Standard Model itself, and also the experimentalists at CERN and other institutions who made possible the proof of the Higgs field and boson in reality. The Nobel prize has a limit of 3 persons to share an award, and some possible winners are already prize holders for other work, or are deceased (the prize is only awarded to persons in their lifetime). Existing prizes for works relating to the Higgs field, boson, or mechanism include:
- Nobel Prize in Physics (1979) – Weinberg and Salam (and a co-creator), for contributions to the theory of the unified weak and electromagnetic interaction between elementary particles
- Nobel Prize in Physics (1999) – ‘t Hooft and Veltman, for elucidating the quantum structure of electroweak interactions in physics
- Nobel Prize in Physics (2008) – Nambu (shared), for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics
- J. J. Sakurai Prize for Theoretical Particle Physics (2010) – Hagen, Englert, Guralnik, Higgs, Brout, and Kibble, for elucidation of the properties of spontaneous symmetry breaking in four-dimensional relativistic gauge theory and of the mechanism for the consistent generation of vector boson masses
- Wolf Prize (2004) – Englert, Brout, and Higgs
- Nobel Prize in Physics (2013) – Peter Higgs and François Englert, “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”