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Gell-Mann
Murray Gell-Mann (; September 15, 1929 – May 24, 2019) was an American physicist who received the 1969 Nobel Prize in Physics for his work on the theory of elementary particles. He was the Robert Andrews Millikan Professor of Theoretical Physics Emeritus at the California Institute of Technology, a distinguished fellow and one of the co-founders of the Santa Fe Institute, a professor of physics at the University of New Mexico, and the Presidential Professor of Physics and Medicine at the University of Southern California. Gell-Mann spent several periods at CERN, a nuclear research facility in Switzerland, among others as a John Simon Guggenheim Memorial Foundation fellow in 1972. Early life and education Gell-Mann was born in Lower Manhattan to a family of Jewish immigrants from the Austro-Hungarian Empire, specifically from Czernowitz in present-day Ukraine. His parents were Pauline (née Reichstein) and Arthur Isidore Gell-Mann, who taught English as a second language. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Chromodynamics
In theoretical physics, quantum chromodynamics (QCD) is the theory 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. QCD exhibits three salient properties: * Color confinement. Due to the force between two color charges remaining constant as they are separated, the energy grows until a quark–antiquark pair is spontaneously produced, turning the initial hadron into a pair of hadrons instead of isolating a color charge. Although ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quark
A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly observable matter is composed of up quarks, down quarks and electrons. Owing to a phenomenon known as ''color confinement'', quarks are never found in isolation; they can be found only within hadrons, which include baryons (such as protons and neutrons) and mesons, or in quark–gluon plasmas. There is also the theoretical possibility of more exotic phases of quark matter. For this reason, much of what is known about quarks has been drawn from observations of hadrons. Quarks have various intrinsic properties, including electric charge, mass, color charge, and spin. They are the only elementary particles in the Standard Model of particle physics to experience all four fundamental interactions, also known as ''fundamental forces'' (electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gell-Mann–Okubo Mass Formula
In physics, the Gell-Mann–Okubo mass formula provides a sum rule for the masses of hadrons within a specific multiplet, determined by their isospin (''I'') and strangeness (or alternatively, hypercharge) :M = a_0 + a_1 Y + a_2 \left I \left( I + 1 \right)-\frac Y^2 \right, where ''a''0, ''a''1, and ''a''2 are free parameters. The rule was first formulated by Murray Gell-Mann in 1961 and independently proposed by Susumu Okubo in 1962. Isospin and hypercharge are generated by SU(3), which can be represented by eight hermitian and traceless matrices corresponding to the "components" of isospin and hypercharge. Six of the matrices correspond to flavor change, and the final two correspond to the third-component of isospin projection, and hypercharge. Theory The mass formula was obtained by considering the representations of the Lie algebra su(3). In particular, the meson octet corresponds to the root system of the adjoint representation. However, the simplest, lowest-dimensional r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quark Model
In particle physics, the quark model is a classification scheme for hadrons in terms of their valence quarks—the quarks and antiquarks which give rise to the quantum numbers of the hadrons. The quark model underlies "flavor SU(3)", or the Eightfold Way, the successful classification scheme organizing the large number of lighter hadrons that were being discovered starting in the 1950s and continuing through the 1960s. It received experimental verification beginning in the late 1960s and is a valid effective classification of them to date. The model was independently proposed by physicists Murray Gell-Mann, who dubbed them "quarks" in a concise paper, and George Zweig, who suggested "aces" in a longer manuscript. André Petermann also touched upon the central ideas from 1963 to 1965, without as much quantitative substantiation. Today, the model has essentially been absorbed as a component of the established quantum field theory of strong and electroweak particle interactions, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gell-Mann Matrices
The Gell-Mann matrices, developed by Murray Gell-Mann, are a set of eight linearly independent 3×3 traceless Hermitian matrices used in the study of the strong interaction in particle physics. They span the Lie algebra of the SU(3) group in the defining representation. Matrices : Properties These matrices are traceless, Hermitian, and obey the extra trace orthonormality relation (so they can generate unitary matrix group elements of SU(3) through exponentiation). These properties were chosen by Gell-Mann because they then naturally generalize the Pauli matrices for SU(2) to SU(3), which formed the basis for Gell-Mann's quark model. Gell-Mann's generalization further extends to general SU(''n''). For their connection to the standard basis of Lie algebras, see the Weyl–Cartan basis. Trace orthonormality In mathematics, orthonormality typically implies a norm which has a value of unity (1). Gell-Mann matrices, however, are normalized to a value of 2. Thus, the trace o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Renormalization Group
In theoretical physics, the term renormalization group (RG) refers to a formal apparatus that allows systematic investigation of the changes of a physical system as viewed at different scales. In particle physics, it reflects the changes in the underlying force laws (codified in a quantum field theory) as the energy scale at which physical processes occur varies, energy/momentum and resolution distance scales being effectively conjugate under the uncertainty principle. A change in scale is called a scale transformation. The renormalization group is intimately related to ''scale invariance'' and ''conformal invariance'', symmetries in which a system appears the same at all scales (so-called self-similarity). As the scale varies, it is as if one is changing the magnifying power of a notional microscope viewing the system. In so-called renormalizable theories, the system at one scale will generally be seen to consist of self-similar copies of itself when viewed at a smaller sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gell-Mann And Low Theorem
The Gell-Mann and Low theorem is a theorem in quantum field theory that allows one to relate the ground (or vacuum) state of an interacting system to the ground state of the corresponding non-interacting theory. It was proved in 1951 by Murray Gell-Mann and Francis E. Low. The theorem is useful because, among other things, by relating the ground state of the interacting theory to its non-interacting ground state, it allows one to express Green's functions (which are defined as expectation values of Heisenberg-picture fields in the interacting vacuum) as expectation values of interaction picture fields in the non-interacting vacuum. While typically applied to the ground state, the Gell-Mann and Low theorem applies to any eigenstate of the Hamiltonian. Its proof relies on the concept of starting with a non-interacting Hamiltonian and adiabatically switching on the interactions. History The theorem was proved first by Gell-Mann and Low in 1951, making use of the Dyson series. In 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gell-Mann–Nishijima Formula
The Gell-Mann–Nishijima formula (sometimes known as the NNG formula) relates the baryon number ''B'', the strangeness ''S'', the isospin ''I3'' of quarks and hadrons to the electric charge ''Q''. It was originally given by Kazuhiko Nishijima and Tadao Nakano in 1953, and led to the proposal of strangeness as a concept, which Nishijima originally called "eta-charge" after the eta meson. Murray Gell-Mann proposed the formula independently in 1956. The modern version of the formula relates all flavour quantum numbers (isospin up and down, strangeness, charm, bottomness, and topness) with the baryon number and the electric charge. Formula The original form of the Gell-Mann–Nishijima formula is: :Q = I_3 + \frac (B+S)\ This equation was originally based on empirical experiments. It is now understood as a result of the quark model. In particular, the electric charge ''Q'' of a quark or hadron particle is related to its isospin ''I3'' and its hypercharge ''Y'' via the relation: : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santa Fe Institute
The Santa Fe Institute (SFI) is an independent, nonprofit theoretical research institute located in Santa Fe, New Mexico, United States and dedicated to the multidisciplinary study of the fundamental principles of complex adaptive systems, including physical, computational, biological, and social systems. The institute is ranked 24th among the world's "Top Science and Technology Think Tanks" and 24th among the world's "Best Transdisciplinary Research Think Tanks" according to the 2020 edition of the ''Global Go To Think Tank Index Reports'', published annually by the University of Pennsylvania. The institute consists of a small number of resident faculty and postdoctoral researchers, a large group of external faculty whose primary appointments are at other institutions, and a number of visiting scholars. The institute is advised by a group of eminent scholars, including several Nobel Prize-winning scientists. Although theoretical scientific research is the institute's primary focu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rod Crewther
Rodney James Crewther (23 September 1945 – 17 December 2020) was a physicist, notable in the field of gauge field theories. Education After gaining his MSc at Melbourne University, Crewther was awarded a Fulbright scholarship to the California Institute of Technology. He studied under the tutelage of Nobel prizewinner Murray Gell-Mann and completed his doctorate, in 1971, after successfully defending his dissertation against the renowned theorist Richard Feynman. His thesis was entitled ''Spontaneous Breakdown of Conformal and Chiral Invariance.'' Career After his PhD, he held postdoctoral appointments at Cornell University in Ithaca, New York and the Fermi National Accelerator Laboratory in Batavia, Illinois. Subsequently, he spent twelve years in Europe, six of them as a Staff Member of the European Laboratory for Particle Physics (CERN) in Geneva, and the remainder as a research associate at the University of Berne, University of Dortmund, and at the Max Planck Institute i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barton Zwiebach
Barton Zwiebach (born ''Barton Zwiebach Cantor'', October 4, 1954) is a Peruvian string theorist and professor at the Massachusetts Institute of Technology. Work Zwiebach's undergraduate work was in Electrical Engineering at the Universidad Nacional de Ingeniería in Peru, from which he graduated in 1977. His graduate work was in physics at the California Institute of Technology. Zwiebach obtained his Ph.D. in 1983, working under the supervision of Murray Gell-Mann. He has held postdoctoral positions at the University of California, Berkeley, and at the Massachusetts Institute of Technology, where he became an assistant professor of physics in 1987, and a permanent member of the faculty in 1994. He is one of the world's leading experts in string field theory String or strings may refer to: *String (structure), a long flexible structure made from threads twisted together, which is used to tie, bind, or hang other objects Arts, entertainment, and media Films * Strings (1991 f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sidney Coleman
Sidney Richard Coleman (7 March 1937 – 18 November 2007) was an American theoretical physics, theoretical physicist noted for his research in high-energy theoretical physics. Life and work Sidney Coleman grew up on the Far North Side of Chicago. In 1957, he received his undergraduate degree from the Illinois Institute of Technology IIT Physics Department, physics department. Coleman received his Doctor of Philosophy, Ph.D. from the California Institute of Technology in 1962, where he was advised by Murray Gell-Mann. He moved to Harvard University that year, where he spent his entire career, meeting his wife Diana there in the late 1970s. They were married in 1982. "He was a giant in a peculiar sense, because he's not known to the general populace," Nobel laureate Sheldon Glashow told the Boston Globe. "He's not a Stephen Hawking; he has virtually no visibility outside. But within the community of theoretical physicists, he's kind of a major god. He is the physicist's p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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