John Michael Cornwall (born 19 August 1934 in Denver, Colorado) is an American theoretical physicist who does research on elementary particle physics and quantum field theory as well as geophysics and physics of near-space. He is known for the Pinch Technique. [1] [2]
Cornwall graduated from Harvard University with a bachelor's degree in 1956 and from the University of Denver with a master's degree in 1959. He graduated in 1962 from the University of California, Berkeley with a doctorate under the supervision of Malvin Ruderman. [3] Cornwall was a postdoctoral fellow at the California Institute of Technology (Caltech) and from 1963 to 1965 at the Institute for Advanced Study. [4] At the University of California, Los Angeles (UCLA) he became in 1965 an assistant professor and in 1974 a full professor.
Cornwall invented the Pinch Technique for calculating gauge-invariant off-shell Green's functions for QCD and other Yang-Mills theories, showing how a dynamical gauge-invariant mass arises for QCD gluons and how such gluons, with the long-range pure-gauge fields that necessarily accompany gauge-invariant mass generation, lead to confinement and other non-perturbative phenomena. He has also written some 40 papers on space plasmas such as the aurora, the ionosphere, and the magnetospheric ring current, leading among other things to a detailed understanding of the dynamical role of electromagnetic cyclotron instabilities in the magnetosphere.
Cornwall published with Richard E. Norton in 1973 one of the earliest papers on dynamic symmetry breaking in Yang-Mills theories. [5] In the later part of his career he has worked on non-perturbative quantum chromodynamics. [4]
He was an advisor to the Space Sciences Laboratory of the Aerospace Corporation in El Segundo (1962–1993) and to the Institute for Defense Analyses in Alexandria (2002–2015), as well as to the National Aeronautics and Space Administration (NASA). He was a faculty member of the Pardee RAND Graduate School of Public Policy (1999–2005) and a member of the Defense Science Board (1992–1994). For some years he has been a member and now chairman of an advisory board at Livermore National Laboratory (1989–present), and is a long-term member of the JASON Advisory Group.
He was from 1967 to 1969 a Sloan Fellow and from 1968 to 1969 a visiting scientist at the Niels Bohr Institute in Copenhagen. He was a visiting professor for the academic year 1987–1988 at the Massachusetts Institute of Technology and in 1989 at Rockefeller University.
He is a Fellow of the American Physical Society (2005), [6] the New York Academy of Sciences, the American Geophysical Union, and the American Association for the Advancement of Science.
In theoretical physics, quantum chromodynamics (QCD) is the study of the strong interaction between quarks mediated by gluons. Quarks are fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD is a type of quantum field theory called a non-abelian gauge theory, with symmetry group SU(3). The QCD analog of electric charge is a property called color. Gluons are the force carriers of the theory, just as photons are for the electromagnetic force in quantum electrodynamics. The theory is an important part of the Standard Model of particle physics. A large body of experimental evidence for QCD has been gathered over the years.
The Standard Model of particle physics is the theory describing three of the four known fundamental forces in the universe and classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists worldwide, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, proof of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.
Technicolor theories are models of physics beyond the Standard Model that address electroweak gauge symmetry breaking, the mechanism through which W and Z bosons acquire masses. Early technicolor theories were modelled on quantum chromodynamics (QCD), the "color" theory of the strong nuclear force, which inspired their name.
In quantum physics an anomaly or quantum anomaly is the failure of a symmetry of a theory's classical action to be a symmetry of any regularization of the full quantum theory. In classical physics, a classical anomaly is the failure of a symmetry to be restored in the limit in which the symmetry-breaking parameter goes to zero. Perhaps the first known anomaly was the dissipative anomaly in turbulence: time-reversibility remains broken at the limit of vanishing viscosity.
In particle and condensed matter physics, Goldstone bosons or Nambu–Goldstone bosons (NGBs) are bosons that appear necessarily in models exhibiting spontaneous breakdown of continuous symmetries. They were discovered by Yoichiro Nambu in particle physics within the context of the BCS superconductivity mechanism, and subsequently elucidated by Jeffrey Goldstone, and systematically generalized in the context of quantum field theory. In condensed matter physics such bosons are quasiparticles and are known as Anderson–Bogoliubov modes.
In quantum field theory, asymptotic freedom is a property of some gauge theories that causes interactions between particles to become asymptotically weaker as the energy scale increases and the corresponding length scale decreases.
In physics, an infrared fixed point is a set of coupling constants, or other parameters, that evolve from arbitrary initial values at very high energies to fixed, stable values, usually predictable, at low energies. This usually involves the use of the renormalization group, which specifically details the way parameters in a physical system depend on the energy scale being probed.
Alternative models to the Standard Higgs Model are models which are considered by many particle physicists to solve some of the Higgs boson's existing problems. Two of the most currently researched models are quantum triviality, and Higgs hierarchy problem.
A conformal anomaly, scale anomaly, trace anomaly or Weyl anomaly is an anomaly, i.e. a quantum phenomenon that breaks the conformal symmetry of the classical theory.
In particle physics, the history of quantum field theory starts with its creation by Paul Dirac, when he attempted to quantize the electromagnetic field in the late 1920s. Major advances in the theory were made in the 1940s and 1950s, leading to the introduction of renormalized quantum electrodynamics (QED). The field theory behind QED was so accurate and successful in predictions that efforts were made to apply the same basic concepts for the other forces of nature. Beginning in 1954, the parallel was found by way of gauge theory, leading by the late 1970s, to quantum field models of strong nuclear force and weak nuclear force, united in the modern Standard Model of particle physics.
Benjamin Whisoh Lee, or Ben Lee, was a South Korean and American theoretical physicist. His work in theoretical particle physics exerted great influence on the development of the standard model in the late 20th century, especially on the renormalization of the electro-weak model and gauge theory.
In physics, topological order is a kind of order in the zero-temperature phase of matter. Macroscopically, topological order is defined and described by robust ground state degeneracy and quantized non-abelian geometric phases of degenerate ground states. Microscopically, topological orders correspond to patterns of long-range quantum entanglement. States with different topological orders cannot change into each other without a phase transition.
Erick J. Weinberg is a theoretical physicist and professor of physics at Columbia University.
In theoretical physics, the unitarity gauge or unitary gauge is a particular choice of a gauge fixing in a gauge theory with a spontaneous symmetry breaking. In this gauge, the scalar fields responsible for the Higgs mechanism are transformed into a basis in which their Goldstone boson components are set to zero. In other words, the unitarity gauge makes the manifest number of scalar degrees of freedom minimal.
In strong interaction physics, light front holography or light front holographic QCD is an approximate version of the theory of quantum chromodynamics (QCD) which results from mapping the gauge theory of QCD to a higher-dimensional anti-de Sitter space (AdS) inspired by the AdS/CFT correspondence proposed for string theory. This procedure makes it possible to find analytic solutions in situations where strong coupling occurs, improving predictions of the masses of hadrons and their internal structure revealed by high-energy accelerator experiments. The most widely used approach to finding approximate solutions to the QCD equations, lattice QCD, has had many successful applications; It is a numerical approach formulated in Euclidean space rather than physical Minkowski space-time.
In theoretical physics, a mass generation mechanism is a theory that describes the origin of mass from the most fundamental laws of physics. Physicists have proposed a number of models that advocate different views of the origin of mass. The problem is complicated because the primary role of mass is to mediate gravitational interaction between bodies, and no theory of gravitational interaction reconciles with the currently popular Standard Model of particle physics.
Kameshwar C. Wali was an Indian-born American theoretical physicist who was the Distinguished Research Professor of Physics Emeritus at Syracuse University's College of Arts and Sciences. He was a specialist in high energy physics, particularly symmetries and dynamics of elementary particles, and the author of Chandra: A Biography of S. Chandrasekhar and Cremona Violins: a physicist's quest for the secrets of Stradivari.
Ramamurti Rajaraman is an emeritus professor of theoretical physics at the School of Physical Sciences at Jawaharlal Nehru University. He was also the co-Chairman of the International Panel on Fissile Materials and a member of the Bulletin of the Atomic Scientists' Science and Security Board. He has taught and conducted research in physics at the Indian Institute of Science, the Institute for Advanced Study at Princeton, and as a visiting professor at Stanford, Harvard, MIT, and elsewhere. He received his doctorate in theoretical physics in 1963 from Cornell University. In addition to his physics publications, Rajaraman has written widely on topics including fissile material production in India and Pakistan and the radiological effects of nuclear weapon accidents.
Daya Shankar Kulshreshtha is an Indian theoretical physicist, specializing in formal aspects of quantum field theory, string theory, supersymmetry, supergravity and superstring theory, Dirac's instant-form and light-front quantization of field theories and D-brane actions. His work on the models of gravity focuses on the studies of charged compact boson stars and boson shells.
Kenneth Alan Johnson was an American theoretical physicist. He was professor of physics at MIT, a leader in the study of quantum field theories and the quark substructure of matter. Johnson contributed to the understanding of symmetry and anomalies in quantum field theories and to models of quark confinement and dynamics in quantum chromodynamics.