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Dual Resonance Model
In theoretical physics, a dual resonance model arose during the early investigation (1968–1973) of string theory as an S-matrix theory of the strong interaction. Overview The dual resonance model was based upon the observation that the amplitudes for the s-channel scatterings matched exactly with the amplitudes for the t-channel scatterings among mesons and also the Regge trajectory. It began with the Euler beta function model of Gabriele Veneziano in 1968 for a 4-particle amplitude which has the property that it is explicitly s–t crossing symmetric, exhibits duality between the description in terms of Regge poles or of resonances, and provides a closed-form solution to non-linear finite-energy sum rules relating s- and t- channels. The Veneziano formula was quickly generalized to an equally consistent ''N''-particle amplitude for which Yoichiro Nambu, Holger Bech Nielsen, and Leonard Susskind provided a physical interpretation in terms of an infinite number of simple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Physics
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict List of natural phenomena, natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena. The advancement of science generally depends on the interplay between experimental studies and theory. In some cases, theoretical physics adheres to standards of mathematical rigour while giving little weight to experiments and observations.There is some debate as to whether or not theoretical physics uses mathematics to build intuition and illustrativeness to extract physical insight (especially when normal experience fails), rather than as a tool in formalizing theories. This links to the question of it using mathematics in a less formally rigorous, and more intuitive or heuristic way than, say, mathematical physics. For example, while developing special relativity, Albert E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holger Bech Nielsen
Holger Bech Nielsen (born 25 August 1941) is a Danish theoretical physicist and professor emeritus at the Niels Bohr Institute, at the University of Copenhagen, where he started studying physics in 1961. Work Nielsen has made original contributions to theoretical particle physics, specifically in the field of string theory. Independently of Yoichiro Nambu and Leonard Susskind, he was the first to propose that the Veneziano model was actually a theory of strings, leading him to be considered among the fathers of string theory. He was awarded the Humboldt Prize in 2001 for his research. Several physics concepts are named after him, e.g. Nielsen–Olesen vortex and the Nielsen-Ninomiya no-go theorem for representing chiral fermions on the lattice. In the original dual-models, which later would be recognized as the origins of string theory, the Koba–Nielsen variables are also named after him and his collaborator Ziro Koba. Nielsen is known in Denmark for his enthusiastic p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lund String Model
In particle physics, the Lund string model is a phenomenological model of hadronization. It treats all but the highest-energy gluons as field lines, which are attracted to each other due to the gluon self-interaction and so form a narrow tube (or string) of strong color field. ( Electromagnetic field lines do not stringify, but instead spread out, because the photon, carrier of the electromagnetic force, does not self-interact.) The model is named after the particle theory group of Lund University who developed it. It derived from the 1977 PhD thesis of Carsten Peterson, supervised by Bo Andersson and Gösta Gustafson. The model was refined by the contributions by researchers of the group like Torbjörn Sjöstrand, Bo Söderberg, Gunnar Ingelman, Hans-Uno Bengtsson and Ulf Pettersson. In 1979, the model was able to describe gluon jet fragmentation by considered the force field to be similar to a massless relativistic string. The model successfully predicted a specific asymmet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QCD String
In quantum chromodynamics (QCD), color confinement, often simply called confinement, is the phenomenon that color-charged particles (such as quarks and gluons) cannot be isolated, and therefore cannot be directly observed in normal conditions below the Hagedorn temperature of approximately 2 terakelvin (corresponding to energies of approximately 130–140 M eV per particle). Quarks and gluons must clump together to form hadrons. The two main types of hadron are the mesons (one quark, one antiquark) and the baryons (three quarks). In addition, colorless glueballs formed only of gluons are also consistent with confinement, though difficult to identify experimentally. Quarks and gluons cannot be separated from their parent hadron without producing new hadrons. Origin There is not yet an analytic proof of color confinement in any non-abelian gauge theory. The phenomenon can be understood qualitatively by noting that the force-carrying gluons of QCD have color charge, unlike t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymptotic Freedom
In quantum field theory, asymptotic freedom is a property of some gauge theory, gauge theories that causes interactions between particles to become asymptotically weaker as the energy scale increases and the corresponding length scale decreases. (Alternatively, and perhaps contrarily, in applying an S-matrix, asymptotically free refers to free particles states in the distant past or the distant future.) Asymptotic freedom is a feature of quantum chromodynamics (QCD), the quantum field theory of the strong interaction between quarks and gluons, the fundamental constituents of nuclear matter. Quarks interact weakly at high energies, allowing Perturbation theory (quantum mechanics), perturbative calculations. At low energies, the interaction becomes strong, leading to the color confinement, confinement of quarks and gluons within composite hadrons. The asymptotic freedom of QCD was discovered in 1973 by David Gross and Frank Wilczek, and independently by David Politzer in the sam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Chromodynamics
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 special unitary 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 Quantum chromodynamics#Experimental tests, 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 mass–energy equivalence, spontaneously produced, turning ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sergio Fubini
Sergio Fubini (31 December 1928 – 6 January 2005) was an Italian theoretical physicist. He was one of the pioneers of string theory. He was engaged in peace activism in the Middle East. Biography Fubini was born in Turin. In 1938, he fled the country as a politically persecuted Jew to Switzerland. In 1945, he attended the Lycée in Turin, where he studied physics and in 1950 graduated "cum laude." Afterwards, he was an assistant in Turin. From 1954 to 1957, he was in the USA. From 1958 to 1967, he was at CERN in Geneva Geneva ( , ; ) ; ; . is the List of cities in Switzerland, second-most populous city in Switzerland and the most populous in French-speaking Romandy. Situated in the southwest of the country, where the Rhône exits Lake Geneva, it is the ca .... In 1959, he became a professor of nuclear physics at University of Padua. In 1961, he became a professor of theoretical physics at University of Turin. From 1968 to 1973, he was at MIT, but taught summer co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String Theory
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string acts like a particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries the gravitational force. Thus, string theory is a theory of quantum gravity. String theory is a broad and varied subject that attempts to address a number of deep questions of fundamental physics. String theory has contributed a number of advances to mathematical physics, which have been applied to a variety of problems in black hole physics, early universe cosmology, nuclear physics, and condensed matter ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simple Harmonic Oscillator
In mechanics and physics, simple harmonic motion (sometimes abbreviated as ) is a special type of periodic function, periodic motion an object experiences by means of a restoring force whose magnitude is directly proportionality (mathematics), proportional to the distance of the object from an equilibrium position and acts towards the equilibrium position. It results in an oscillation that is described by a sinusoid which continues indefinitely (if uninhibited by friction or any other dissipation of energy). Simple harmonic motion can serve as a mathematical model for a variety of motions, but is typified by the oscillation of a mass on a spring (device), spring when it is subject to the linear elasticity (physics), elastic restoring force given by Hooke's law. The motion is sinusoidal in time and demonstrates a single resonance, resonant frequency. Other phenomena can be modeled by simple harmonic motion, including the motion of a pendulum, simple pendulum, although for it to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leonard Susskind
Leonard Susskind (; born June 16, 1940)his 60th birth anniversary was celebrated with a special symposium at Stanford University.in Geoffrey West's introduction, he gives Suskind's current age as 74 and says his birthday was recent. is an American theoretical physicist, professor of theoretical physics at Stanford University and founding director of the Stanford Institute for Theoretical Physics. His research interests are string theory, quantum field theory, quantum statistical mechanics and quantum cosmology. He is a member of the US National Academy of Sciences, and the American Academy of Arts and Sciences, an associate member of the faculty of Canada's Perimeter Institute for Theoretical Physics, and a distinguished professor of the Korea Institute for Advanced Study. Susskind is widely regarded as one of the fathers of string theory. He was the first to give a precise string-theoretic interpretation of the holographic principle in 1995 and the first to introduce the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nordita
The Nordic Institute for Theoretical Physics, or NORDITA, or Nordita (), is an international organisation for research in theoretical physics. It was established as Nordisk Institut for Teoretisk Atomfysik in 1957 by Niels Bohr and the Swedish physicist Torsten Gustafson. Nordita was originally located at the Niels Bohr Institute in Copenhagen (Denmark), but moved to the AlbaNova University Centre in Stockholm (Sweden) on 1 January 2007. The main research areas at Nordita are astrophysics, hard and soft condensed matter physics, and high-energy physics. Research Since Nordita's establishment in 1957 the original focus on research in atomic and nuclear physics has been broadened. Research carried out by Nordita's academic staff presently includes astrophysics, biological physics, hard condensed matter physics and materials physics, soft condensed matter physics, cosmology, statistical physics and complex systems, high-energy physics, and gravitational physics and cos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yoichiro Nambu
was a Japanese-American physicist and professor at the University of Chicago. Known for his groundbreaking contributions to theoretical physics, Nambu was the originator of the theory of spontaneous symmetry breaking, a concept that revolutionized particle physics. He was also a pioneer of quantum chromodynamics (QCD), one of the founding figures of string theory, and the proposer of Nambu mechanics. In addition, he co-created the Nambu–Jona-Lasinio model, which explained the dynamical origin of mass in nucleons. He was awarded half of the Nobel Prize in Physics in 2008 for the discovery in 1960 of the mechanism of spontaneous broken symmetry in subatomic physics, related at first to the strong interaction's chiral symmetry and later to the electroweak interaction and Higgs mechanism. The other half was split equally between Makoto Kobayashi and Toshihide Maskawa "for the discovery of the origin of the broken symmetry which predicts the existence of at least three ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
