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John Ellis (physicist)
Encyclopedia
Jonathan Richard Ellis FRS (born July 1, 1946) is a British
theoretical physicist
who is currently Clerk Maxwell Professor of Theoretical Physics at King's College London
. After completing his secondary education at Highgate School
, he attended Cambridge University
, earning his Ph.D. in theoretical (high-energy) particle physics in 1971. After brief post-doc positions at SLAC and Caltech, he went to CERN
and has held an indefinite contract there since 1978. He was awarded the Maxwell Medal
and the Paul Dirac Prize by the Institute of Physics
in 1982 and 2005 respectively, and is an Elected Fellow of the Royal Society of London since 1985 and of the Institute of Physics since 1991. He was awarded an Honorary Doctorate from the University of Southampton
, and twice won the First Award in the Gravity Research Foundation
essay competition (in 1999 and 2005). He is also Honorary Doctor at Uppsala University.
Ellis' activities at CERN are wide-ranging. He was twice Deputy Division Leader for the theory ("TH") division, and served as Division Leader for 1988–1994. He was a founding member of the LEPC and of the LHCC; currently he is chair of the committee to investigate physics opportunities for future proton accelerators, and is a member of the extended CLIC
(Compact Linear Collider) Steering Committee.
Ellis' early research accomplishments are centered on the phenomenology of gauge theories. Working with Dimitri Nanopoulos
and Mary Gaillard, he proposed in 1976 the so-called Higgs-strahlung process in which a Higgs boson
is radiated from a Z-boson (this proved to be the best way to search for the Higgs boson at LEP), and in the same year estimated the direct CP-violation contribution to rare neutral kaon decays (which led to the success of the NA31 and NA48 experiments at CERN). Also in 1976, he published two papers suggesting techniques for finding the gluon
in annihilations. The following year he predicted the mass of the bottom quark
on the basis of Grand Unified Theory, before this quark was observed in experiment. In 1978 he published a frequently cited general paper on such theories, with Andrzej J. Buras, Gaillard and Nanopoulos.
In the 1980s, Ellis became a leading advocate of models of supersymmetry
. In one of his earliest works, he showed that the lightest supersymmetric particle is a natural Dark Matter
candidate. In 1991, he showed that radiative corrections to the mass of the lightest Higgs boson
in minimal supersymmetric models increased that mass beyond the reach of the LEP searches. The search for the Higgs boson remains one of the most important topics in particle physics, motivating researchers at both the Fermilab
Tevatron
and at the CERN
LHC
. More generally, Ellis and collaborators pioneered the analysis of so-called benchmark scenarios meant to illustrate the range of phenomenology to be expected from supersymmetric models; such analyses have played a major role in evaluating the promise of various future accelerator options.
In parallel to his investigations of supersymmetric phenomenology, Ellis has also advocated phenomenological probes of quantum gravity
and string theory
. These probes include direct tests of quantum mechanics with the CPLEAR Collaboration and the derivation of Grand Unified Theories from string theory. In this vein, his work on tests of the constancy of the velocity of light and models of string cosmology received separate prizes from the Gravity Research Foundation
.
An impression of the impact of Ellis' research can be obtained from the SPIRES
reference system for scientific papers in particle physics and related fields. As of 2008, this data base lists over 850 scientific papers of which he is an author; altogether the sum of citations is above 40,000. In 2004 a SPIRES survey ranked him as the second most-cited theoretical physicist. His publications include one paper with over 1000 citations, six more with over 500 citations, and 104 other papers with at least 100 citations each.
, and extending to CLIC
, photon colliders, and future proton accelerators. Naturally his theoretical work reflected these connections, as when he showed that data from the SLC and from LEP could be used to predict the masses of the top quark and the Higgs boson. Such predictions are now a main stream activity within particle physics, and constitute one of the most important bridges between the experimental and theoretical communities.
Concerning the LHC
, Ellis played a leading role in the seminal 1984 workshop on physics to be done with such an accelerator. Since then he has written many articles on searches for Higgs bosons and supersymmetric particles at the LHC, both for the pariticle physics community and at a more popular level. His most recent LHC physics review appeared in a Nature
Insight supplement on July 19, 2007.
John Ellis has been a strong supporter of the CLIC
option for a future high-energy linear collider; this option is pursued most strongly at CERN. He was convenor of the CLIC Physics Study Group the produced the main report on this option, in 2004.
Ellis is frequently invited to give public lectures on particle physics and related topics. For example, in the two-year period 2004–5, he gave public lectures in Geneva (in French), in Granada and Barcelona (in Spanish), in Rome (in Italian) and in Warsaw (in English).
While at CERN he often gives introductory talks to visitors, ranging from official delegations from the United Kingdom to physics teachers at the high-school level.
Ellis is well known for his efforts to involve non-European nations in CERN scientific activities. In the context of the LHC, he has interacted frequently with physicists, administrators at universities and institutes and ministers of funding agencies and diplomatic corps from a wide variety of countries, ranging from major CERN partners like the United States, Russia, Japan, Canada, India, Israel, Armenia and China, to states with nascent physics programs such as Azerbaijan, the Baltic republics, Bolivia, Colombia, Croatia, Cyprus, Iran, Madagascar, New Zealand, Pakistan, Romania, Sri Lanka, Vietnam, and lately in Palestine, and many others. These interactions have fostered the international character of CERN and opened the pathways of scientific discourse all around the world.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
theoretical physicist
Theoretical physics
Theoretical physics is a branch of physics which employs mathematical models and abstractions of physics to rationalize, explain and predict natural phenomena...
who is currently Clerk Maxwell Professor of Theoretical Physics at King's College London
King's College London
King's College London is a public research university located in London, United Kingdom and a constituent college of the federal University of London. King's has a claim to being the third oldest university in England, having been founded by King George IV and the Duke of Wellington in 1829, and...
. After completing his secondary education at Highgate School
Highgate School
-Notable members of staff and governing body:* John Ireton, brother of Henry Ireton, Cromwellian General* 1st Earl of Mansfield, Lord Chief Justice, owner of Kenwood, noted for judgment finding contracts for slavery unenforceable in English law* T. S...
, he attended Cambridge University
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
, earning his Ph.D. in theoretical (high-energy) particle physics in 1971. After brief post-doc positions at SLAC and Caltech, he went to CERN
CERN
The European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
and has held an indefinite contract there since 1978. He was awarded the Maxwell Medal
Maxwell Medal and Prize
The Maxwell Medal and Prize is one of the principal awards made annually by the Institute of Physics. The award is made for outstanding contributions to theoretical physics and is intended to recognize theoretical physicists early in their careers....
and the Paul Dirac Prize by the Institute of Physics
Institute of Physics
The Institute of Physics is a scientific charity devoted to increasing the practice, understanding and application of physics. It has a worldwide membership of around 40,000....
in 1982 and 2005 respectively, and is an Elected Fellow of the Royal Society of London since 1985 and of the Institute of Physics since 1991. He was awarded an Honorary Doctorate from the University of Southampton
University of Southampton
The University of Southampton is a British public university located in the city of Southampton, England, a member of the Russell Group. The origins of the university can be dated back to the founding of the Hartley Institution in 1862 by Henry Robertson Hartley. In 1902, the Institution developed...
, and twice won the First Award in the Gravity Research Foundation
Gravity Research Foundation
The Gravity Research Foundation, established in 1948 by businessman Roger Babson , was an organization designed to find ways to implement gravitational shielding...
essay competition (in 1999 and 2005). He is also Honorary Doctor at Uppsala University.
Ellis' activities at CERN are wide-ranging. He was twice Deputy Division Leader for the theory ("TH") division, and served as Division Leader for 1988–1994. He was a founding member of the LEPC and of the LHCC; currently he is chair of the committee to investigate physics opportunities for future proton accelerators, and is a member of the extended CLIC
Compact Linear Collider
The Compact Linear Collider is a proposed linear particle accelerator under design at CERN. CLIC is separate from the International Linear Collider project, and differs from it using normal conducting cavities to achieve a higher planned energy of several TeV.Currently research is in progress to...
(Compact Linear Collider) Steering Committee.
Scientific research
Ellis' research interests focus on the phenomenological aspects of particle physics, though he has also made important contributions to astrophysics, cosmology and quantum gravity. Most of his publications relate directly to experiment, from interpreting measurements and the results of searches for new particles, to exploring the physics that could be done with future accelerators. He was one of the pioneers of research at the interface between particle physics and cosmology, which has since become a sub-specialty of its own: particle astrophysics.Ellis' early research accomplishments are centered on the phenomenology of gauge theories. Working with Dimitri Nanopoulos
Dimitri Nanopoulos
Dimitri Nanopoulos is a Greek physicist. He is one of the most regularly cited researchers in the world, cited more than 35,800 times over across a number of separate branches of science....
and Mary Gaillard, he proposed in 1976 the so-called Higgs-strahlung process in which a Higgs boson
Higgs boson
The Higgs boson is a hypothetical massive elementary particle that is predicted to exist by the Standard Model of particle physics. Its existence is postulated as a means of resolving inconsistencies in the Standard Model...
is radiated from a Z-boson (this proved to be the best way to search for the Higgs boson at LEP), and in the same year estimated the direct CP-violation contribution to rare neutral kaon decays (which led to the success of the NA31 and NA48 experiments at CERN). Also in 1976, he published two papers suggesting techniques for finding the gluon
Gluon
Gluons are elementary particles which act as the exchange particles for the color force between quarks, analogous to the exchange of photons in the electromagnetic force between two charged particles....
in annihilations. The following year he predicted the mass of the bottom quark
Bottom quark
The bottom quark, also known as the beauty quark, is a third-generation quark with a charge of − e. Although all quarks are described in a similar way by the quantum chromodynamics, the bottom quark's large bare mass , combined with low values of the CKM matrix elements Vub and Vcb, gives it a...
on the basis of Grand Unified Theory, before this quark was observed in experiment. In 1978 he published a frequently cited general paper on such theories, with Andrzej J. Buras, Gaillard and Nanopoulos.
In the 1980s, Ellis became a leading advocate of models of supersymmetry
Supersymmetry
In particle physics, supersymmetry is a symmetry that relates elementary particles of one spin to other particles that differ by half a unit of spin and are known as superpartners...
. In one of his earliest works, he showed that the lightest supersymmetric particle is a natural Dark Matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
candidate. In 1991, he showed that radiative corrections to the mass of the lightest Higgs boson
Higgs boson
The Higgs boson is a hypothetical massive elementary particle that is predicted to exist by the Standard Model of particle physics. Its existence is postulated as a means of resolving inconsistencies in the Standard Model...
in minimal supersymmetric models increased that mass beyond the reach of the LEP searches. The search for the Higgs boson remains one of the most important topics in particle physics, motivating researchers at both the Fermilab
Fermilab
Fermi National Accelerator Laboratory , located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics...
Tevatron
Tevatron
The Tevatron is a circular particle accelerator in the United States, at the Fermi National Accelerator Laboratory , just east of Batavia, Illinois, and is the second highest energy particle collider in the world after the Large Hadron Collider...
and at the CERN
CERN
The European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
LHC
LHC
LHC may refer to:* Large Hadron Collider, a particle accelerator and collider located on the Franco-Swiss border near Geneva, SwitzerlandLHC also may refer to:* La hora Chanante, a Spanish comedy television show...
. More generally, Ellis and collaborators pioneered the analysis of so-called benchmark scenarios meant to illustrate the range of phenomenology to be expected from supersymmetric models; such analyses have played a major role in evaluating the promise of various future accelerator options.
In parallel to his investigations of supersymmetric phenomenology, Ellis has also advocated phenomenological probes of quantum gravity
Quantum gravity
Quantum gravity is the field of theoretical physics which attempts to develop scientific models that unify quantum mechanics with general relativity...
and string theory
String theory
String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything , a manner of describing the known fundamental forces and matter in a mathematically complete system...
. These probes include direct tests of quantum mechanics with the CPLEAR Collaboration and the derivation of Grand Unified Theories from string theory. In this vein, his work on tests of the constancy of the velocity of light and models of string cosmology received separate prizes from the Gravity Research Foundation
Gravity Research Foundation
The Gravity Research Foundation, established in 1948 by businessman Roger Babson , was an organization designed to find ways to implement gravitational shielding...
.
An impression of the impact of Ellis' research can be obtained from the SPIRES
Spires
Spires may refer to:* SPIRES, a database for publications in High-Energy Physics* Speyer , a city in Germany* The Spires, a commercial conference centre, operated out of Church House, Belfast by the Presbyterian Church in Ireland...
reference system for scientific papers in particle physics and related fields. As of 2008, this data base lists over 850 scientific papers of which he is an author; altogether the sum of citations is above 40,000. In 2004 a SPIRES survey ranked him as the second most-cited theoretical physicist. His publications include one paper with over 1000 citations, six more with over 500 citations, and 104 other papers with at least 100 citations each.
Support of particle accelerator projects
In addition to his theoretical research, John Ellis has been an advocate and supporter of future accelerators, beginning with LEP and the LHCLHC
LHC may refer to:* Large Hadron Collider, a particle accelerator and collider located on the Franco-Swiss border near Geneva, SwitzerlandLHC also may refer to:* La hora Chanante, a Spanish comedy television show...
, and extending to CLIC
Compact Linear Collider
The Compact Linear Collider is a proposed linear particle accelerator under design at CERN. CLIC is separate from the International Linear Collider project, and differs from it using normal conducting cavities to achieve a higher planned energy of several TeV.Currently research is in progress to...
, photon colliders, and future proton accelerators. Naturally his theoretical work reflected these connections, as when he showed that data from the SLC and from LEP could be used to predict the masses of the top quark and the Higgs boson. Such predictions are now a main stream activity within particle physics, and constitute one of the most important bridges between the experimental and theoretical communities.
Concerning the LHC
LHC
LHC may refer to:* Large Hadron Collider, a particle accelerator and collider located on the Franco-Swiss border near Geneva, SwitzerlandLHC also may refer to:* La hora Chanante, a Spanish comedy television show...
, Ellis played a leading role in the seminal 1984 workshop on physics to be done with such an accelerator. Since then he has written many articles on searches for Higgs bosons and supersymmetric particles at the LHC, both for the pariticle physics community and at a more popular level. His most recent LHC physics review appeared in a Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
Insight supplement on July 19, 2007.
John Ellis has been a strong supporter of the CLIC
Compact Linear Collider
The Compact Linear Collider is a proposed linear particle accelerator under design at CERN. CLIC is separate from the International Linear Collider project, and differs from it using normal conducting cavities to achieve a higher planned energy of several TeV.Currently research is in progress to...
option for a future high-energy linear collider; this option is pursued most strongly at CERN. He was convenor of the CLIC Physics Study Group the produced the main report on this option, in 2004.
Outreach and spreading physics around the world
While at CERN he often gives introductory talks to visitors, ranging from official delegations from the United Kingdom to physics teachers at the high-school level.
Ellis is well known for his efforts to involve non-European nations in CERN scientific activities. In the context of the LHC, he has interacted frequently with physicists, administrators at universities and institutes and ministers of funding agencies and diplomatic corps from a wide variety of countries, ranging from major CERN partners like the United States, Russia, Japan, Canada, India, Israel, Armenia and China, to states with nascent physics programs such as Azerbaijan, the Baltic republics, Bolivia, Colombia, Croatia, Cyprus, Iran, Madagascar, New Zealand, Pakistan, Romania, Sri Lanka, Vietnam, and lately in Palestine, and many others. These interactions have fostered the international character of CERN and opened the pathways of scientific discourse all around the world.