In particle physics, a gauge boson is a force carrier, a bosonic particle that carries any of the fundamental interactions of nature.^[1][2] Elementary particles, whose interactions are described by a gauge theory, interact with each other by the exchange of gauge bosons—usually as virtual particles.

Gauge bosons in the Standard Model[link]

The Standard Model of particle physics recognizes three kinds of gauge bosons: Photons, which carry the electromagnetic interaction; W and Z bosons, which carry the weak interaction; and gluons, which carry the strong interaction.^[3]

Isolated gluons do not occur at low energies because they are color-charged, and subject to color confinement.

Multiplicity of gauge bosons[link]

In a quantized gauge theory, gauge bosons are quanta of the gauge fields. Consequently, there are as many gauge bosons as there are generators of the gauge field. In quantum electrodynamics, the gauge group is U(1); in this simple case, there is only one gauge boson. In quantum chromodynamics, the more complicated group SU(3) has eight generators, corresponding to the eight gluons. The three W and Z bosons correspond (roughly) to the three generators of SU(2) in GWS theory.

Massive gauge bosons[link]

For technical reasons involving gauge invariance, gauge bosons are described mathematically by field equations for massless particles. Therefore, at a naïve theoretical level all gauge bosons are required to be massless, and the forces that they describe are required to be long-ranged. The conflict between this idea and experimental evidence that the weak interaction has a very short range requires further theoretical insight.

According to the Standard Model, the W and Z bosons gain mass via the Higgs mechanism. In the Higgs mechanism, the four gauge bosons (of SU(2)×U(1) symmetry) of the unified electroweak interaction couple to a Higgs field. This field undergoes spontaneous symmetry breaking due to the shape of its interaction potential. As a result, the universe is permeated by a nonzero Higgs vacuum expectation value (VEV). This VEV couples to three of the electroweak gauge bosons (the Ws and Z), giving them mass; the remaining gauge boson remains massless (the photon). This theory also predicts the existence of a scalar Higgs boson, which has not yet been observed.

Beyond the Standard Model[link]

Grand unification theories[link]

A grand unified theory predicts additional gauge bosons named X and Y bosons. The hypothetical X and Y bosons direct interactions between quarks and leptons, hence violating conservation of baryon number and causing proton decay. Such bosons would be even more massive than W and Z bosons due to symmetry breaking. Analysis of data collected from such sources as the Super-Kamiokande neutrino detector has yielded no evidence of X and Y bosons.^{[citation needed]}

Gravitons[link]

The fourth fundamental interaction, gravity, may also be carried by a boson, called the graviton. In the absence of experimental evidence and a mathematically coherent theory of quantum gravity, it is unknown whether this would be a gauge boson or not. The role of gauge invariance in general relativity is played by a similar symmetry: diffeomorphism invariance.

W' and Z' bosons[link]

W' and Z' bosons refer to hypothetical new gauge bosons (named in analogy with the Standard Model W and Z bosons).

See also[link]

	Book: Particles of the Standard Model
Wikipedia books are collections of articles that can be downloaded or ordered in print.

• 1964 PRL symmetry breaking papers
• Boson
• Glueball
• Quantum chromodynamics
• Quantum electrodynamics

References[link]

External links[link]

• Explanation of gauge boson and gauge fields by Christopher T. Hill

Peter Higgs
Peter Higgs at 80th birthday celebrations for Michael Atiyah, April 2009
Born	(1929-05-29) 29 May 1929 (age 83) Newcastle upon Tyne, England
Nationality	British
Fields	Physics
Institutions	University of Edinburgh Imperial College London University College London
Alma mater	King's College London
Doctoral advisor	Charles Coulson
Doctoral students	Christopher Bishop Lewis Ryder David Wallace
Known for	Broken symmetry in electroweak theory
Notable awards	Wolf Prize in Physics (2004) Sakurai Prize (2010) Dirac Medal (1997)

Peter Ware Higgs, FRS, FRSE, FKC (born 29 May 1929), is a British theoretical physicist and an emeritus professor at the University of Edinburgh.^[1]

He is best known for his 1960s proposal of broken symmetry in electroweak theory, explaining the origin of mass of elementary particles in general and of the W and Z bosons in particular. This so-called Higgs mechanism, which had several inventors besides Higgs at about the same time, predicts the existence of a new particle, the Higgs boson (often described as "the most sought-after particle in modern physics"^[2][3]). Although this particle has not turned up in accelerator experiments so far, the Higgs mechanism is generally accepted as an important ingredient in the Standard Model of particle physics, without which particles would have no mass.^[4]

Prof. Higgs has been honoured with a number of awards in recognition of his work, including the 1997 Dirac Medal and Prize for outstanding contributions to theoretical physics from the Institute of Physics, the 1997 High Energy and Particle Physics Prize by the European Physical Society, the 2004 Wolf Prize in Physics, and the 2010 J. J. Sakurai Prize for Theoretical Particle Physics.

Early life, education and career[link]

Higgs was born in Wallsend, North Tyneside, England.^[5] His father worked as a sound engineer for the BBC, and as a result of childhood asthma, together with the family moving around because of his father's job, and later the Second World War, Higgs missed some early schooling and was taught at home. When his father relocated to Bedford, Higgs stayed behind with his mother in Bristol, and was largely raised there. He attended that city's Cotham Grammar School,^[6] where he was inspired by the work of one of the school's alumni, Paul Dirac, a founder of the field of quantum mechanics.^[5]

At the age of 17 Higgs moved to City of London School, where he specialized in mathematics, then to King's College London where he graduated with a first class honours degree in Physics, and later achieved a masters degree, and Ph.D.^[1] He became a Senior Research Fellow at the University of Edinburgh, then held various posts at University College London and Imperial College London before becoming a temporary lecturer in Mathematics at University College London. He returned to the University of Edinburgh in 1960 to take up the post of Lecturer at the Tait Institute of Mathematical Physics, allowing him to settle in the city he had fallen in love with after hitch-hiking to the Edinburgh Fringe festival as a student.^[1]

Dr. Higgs was promoted to a personal chair of Theoretical Physics at Edinburgh in 1980. He became a fellow of the Royal Society in 1983, was awarded the Rutherford Medal and Prize in 1984, and became a fellow of the Institute of Physics in 1991. He retired in 1996 and became Emeritus professor at the University of Edinburgh.^[1] In 2008 he received an Honorary Fellowship from Swansea University for his work in particle physics.^[7]

Work in theoretical physics[link]

At Edinburgh Higgs first became interested in mass, developing the idea that particles were massless when the universe began, acquiring mass a fraction of a second later as a result of interacting with a theoretical field (which became known as the Higgs field). Higgs postulated that this field permeates space, giving all elementary subatomic particles that interact with it their mass.^[5][8] While the Higgs field is postulated to confer mass on quarks and leptons, it causes only a tiny portion of the masses of other subatomic particles, such as protons and neutrons. In these, gluons that bind quarks together confer most of the particle mass.

The original basis of Higgs' work came from the Japanese-born theorist and Nobel Prize winner Yoichiro Nambu from the University of Chicago. Professor Nambu had proposed a theory known as spontaneous symmetry breaking based on what was known to happen in superconductivity in condensed matter. However, the theory predicted massless particles (the Goldstone's theorem), a clearly incorrect prediction.^[1]

Higgs wrote a short paper exploiting a loophole in Goldstone's theorem and published it in Physics Letters, a European physics journal edited at CERN, in Switzerland, in 1964.^[9]

Higgs wrote a second paper describing a theoretical model (now called the Higgs mechanism) but the paper was rejected (the editors of Physics Letters judged it "of no obvious relevance to physics"^[5]). Higgs wrote an extra paragraph and sent his paper to Physical Review Letters, another leading physics-journal, which published it later that year.^[10] Other physicists, Robert Brout and Francois Englert^[11] and Gerald Guralnik, C. R. Hagen, and Tom Kibble^[12] had reached the same conclusion independently about the same time. The three papers written on this boson discovery by Higgs, Guralnik, Hagen, Kibble, Brout, and Englert were each recognized as milestone papers by Physical Review Letters 50th anniversary celebration.^[13] While each of these famous papers took similar approaches, the contributions and differences between the 1964 PRL symmetry breaking papers are noteworthy. Nobelist Philip Anderson also claims to have "invented" the "Higgs" boson as far back as 1962.

As an atheist, Higgs is reported^{[by whom?]} to be displeased that the particle is nicknamed the "God particle". Higgs is afraid the term "might offend people who are religious".^[14][15] This nickname for the Higgs boson is usually attributed to Leon Lederman, but it is actually the result of Lederman's publisher's censoring. Originally Lederman intended to call it "the goddamn particle", because of its elusiveness.^[16]

In December 2011 CERN reported that two independent experiments at the Large Hadron Collider had seen "tantalising hints" of the existence of the Higgs boson.^[17] If the Higgs boson is found at CERN, Higgs and the others who contributed to the Brout-Englert-Higgs-Guralnik-Hagen-Kibble mechanism may receive a Nobel Prize.^[1]

Political views[link]

Higgs was a CND activist while in London and later in Edinburgh, but resigned his membership when the group extended its remit from campaigning against nuclear weapons to campaigning against nuclear power too.^{[5] [18]} He was a Greenpeace member until the group opposed genetically modified organisms.^[18]

Higgs was awarded the 2004 Wolf Prize in Physics (sharing it with Brout and Englert), but he refused to fly to Jerusalem to receive the award because it was a state occasion attended by the then President of Israel, Moshe Katsav, and Higgs is opposed to Israel's actions in Palestine.^[19]

Family[link]

Higgs has two sons: Chris, a computer scientist, and Jonny, a jazz musician.^[14]

Cultural references[link]

A portrait of Peter Higgs was painted by Ken Currie in 2008.^[20] Commissioned by the University of Edinburgh,^[21](Subscription required) it was unveiled on 3 April 2009^[22] and hangs in the entrance of the James Clerk Maxwell Building of the School of Physics and Astronomy.^[20]

Notes and references[link]

External links[link]

• Peter Higgs at the Mathematics Genealogy Project
• Google Scholar List of Papers by PW Higgs
• BBC profile of Peter Higgs
• A photograph of Peter Higgs, Photographs of Peter Higgs, June 2008
• The god of small things - An interview with Peter Higgs in The Guardian
• Peter Higgs: the man behind the boson - An article in the PhysicsWeb about Peter Higgs
• Higgs v Hawking: a battle of the heavyweights that has shaken the world of theoretical physics - An article on the debate between Peter Higgs and Stephen Hawking about the existence of the Higgs boson
• My Life as a Boson - A Lecture by Peter Higgs available in various formats
• blog of an interview
• Physical Review Letters - 50th Anniversary Milestone Papers
• In CERN Courier, Steven Weinberg reflects on spontaneous symmetry breaking
• Physics World, Introducing the little Higgs
• Englert-Brout-Higgs-Guralnik-Hagen-Kibble Mechanism on Scholarpedia
• History of Englert-Brout-Higgs-Guralnik-Hagen-Kibble Mechanism on Scholarpedia
• Sakurai Prize Videos

Lisa Randall
At a conference in 2006
Born	(1962-06-18) June 18, 1962 (age 50) Queens, New York City, New York, United States
Residence	United States
Nationality	American
Fields	Physics
Institutions	Lawrence Berkeley Laboratory University of California, Berkeley Princeton University Massachusetts Institute of Technology Harvard University
Alma mater	Stuyvesant High School Harvard University
Doctoral advisor	Howard Georgi
Doctoral students	Csaba Csáki, Eric Sather, Witold Skiba, Shu-fang Su, Emanuel Katz, Matthew Schwartz, Shiyamala Thambyahpillai, Liam Fitzpatrick
Known for	Randall–Sundrum model Warped Passages
Notable awards	Klopsteg Memorial Award, 2006. Lilienfeld Prize, 2007

Lisa Randall (born June 18, 1962) is an American theoretical physicist and a leading expert on particle physics and cosmology. She works on several of the competing models of string theory in the quest to explain the fabric of the universe. Her best known contribution to the field is the Randall-Sundrum model, first published in 1999 with Raman Sundrum.^[1] She was the first tenured woman in the Princeton University physics department and the first tenured female theoretical physicist at both MIT and Harvard University. She has also written three popular science books and the libretto of an opera.

Early life and education[link]

Randall was born in Queens in New York City to a Jewish family. She is an alumna of Hampshire College Summer Studies in Mathematics and graduated from Stuyvesant High School in 1980,^[2] where she was a classmate of fellow physicist and science popularizer Brian Greene. She won first place in the 1980 Westinghouse Science Talent Search at the age of 18. Randall earned an A.B. at Harvard in 1983, and obtained her Ph.D. in particle physics in 1987 under the direction of Howard Georgi. She was made a fellow of the American Academy of Arts and Sciences in 2004. Randall was featured in Newsweek magazine's "Who's Next" issue of January 2, 2006, as "one of the most promising theoretical physicists of her generation."

Academia[link]

Lisa Randall at CERN

Randall studies particle physics and cosmology at Harvard University, where she is a professor of theoretical physics. Her research concerns elementary particles and fundamental forces, and has involved the study of a wide variety of models, the most recent involving extra dimensions of space. She has also worked on supersymmetry, Standard Model observables, cosmic inflation, baryogenesis, grand unified theories, general relativity. Randall's book Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions was included in the New York Times' 100 notable books of 2005.

Randall earned her PhD from Harvard University and held professorships at MIT and Princeton University before returning to Harvard in 2001. She is a member of the American Academy of Arts and Sciences and the National Academy of Sciences, a fellow of the American Physical Society, and is a past winner of an Alfred P. Sloan Foundation Research Fellowship, a National Science Foundation Young Investigator Award, a DOE Outstanding Junior Investigator Award, and the Westinghouse Science Talent Search. In 2003, she received the Premio Caterina Tomassoni e Felice Pietro Chisesi Award, from the University of Rome, La Sapienza. In autumn, 2004, she was the most cited theoretical physicist of the previous five years. In 2006, she received the Klopsted Award from the American Association of Physics Teachers (AAPT). Professor Randall was featured in Seed Magazine's “2005 Year in Science Icons ” and in Newsweek's “Who's Next in 2006”. She has helped organize numerous conferences and has been on the editorial board of several major theoretical physics journals.

Randall at TED 2006

Personal[link]

Randall's sister, Dana Randall, is a professor of computer science at Georgia Tech.

In 2007, Randall was named one of Time Magazine's 100 Most Influential People (Time 100) under the section for "Scientists & Thinkers." Randall was given this honor for her work regarding the evidence of a higher dimension.^[3]

Randall has written the libretto for an opera, Hypermusic Prologue: A Projective Opera in Seven Planes, in collaboration with the composer Hèctor Parra and IRCAM.

Bibliography[link]

• Warped Passages: Unraveling the Universe's Hidden Dimensions. Ecco. 2005. ISBN 0-06-053108-8. 
• Knocking on Heaven’s Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World. Ecco. 2011. ISBN 0-06-172372-X. 

References[link]

External links[link]

Wikiquote has a collection of quotations related to: Lisa Randall

Wikimedia Commons has media related to: Lisa Randall

• Professor Randall's website at Harvard
• Reprinted Op-Ed from The New York Times of Sunday, September 18, 2005
• Lisa Randall's Edge Bio Page
• On Gravity, Oreos and a Theory of Everything (New York Times, November 1, 2005)
• Radio Interview from This Week in Science May 9, 2006 Broadcast
• Profile in Scientific American October 2005
• Lisa Randall discusses "Warped Passages" on Thoughtcast
• Lisa Randall is interviewed by Charlie Rose