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Axions
An axion () is a hypothetical elementary particle originally theorized in 1978 independently by Frank Wilczek and Steven Weinberg as the Goldstone boson of Peccei–Quinn theory, which had been proposed in 1977 to solve the strong CP problem in quantum chromodynamics (QCD). If axions exist and have low mass within a specific range, they are of interest as a possible component of cold dark matter. History Strong CP problem As shown by Gerard 't Hooft, strong interactions of the Standard Model, QCD, possess a non-trivial vacuum structure that in principle permits violation of the combined symmetries of charge conjugation and parity, collectively known as CP. Together with effects generated by weak interactions, the effective periodic strong CP-violating term, , appears as a Standard Model input – its value is not predicted by the theory, but must be measured. However, large CP-violating interactions originating from QCD would induce a large electric dipole moment (EDM) for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frank Wilczek
Frank Anthony Wilczek ( or ; born May 15, 1951) is an American theoretical physicist, mathematician and Nobel laureate. He is the Herman Feshbach Professor of Physics at the Massachusetts Institute of Technology (MIT), Founding Director of T. D. Lee Institute and Chief Scientist at the Wilczek Quantum Center, Shanghai Jiao Tong University (SJTU), distinguished professor at Arizona State University (ASU) during February and March and full professor at Stockholm University. Wilczek, along with David Gross and H. David Politzer, was awarded the Nobel Prize in Physics in 2004 "for the discovery of asymptotic freedom in the theory of the strong interaction". In May 2022, he was awarded the Templeton Prize for his "investigations into the fundamental laws of nature, that has transformed our understanding of the forces that govern our universe and revealed an inspiring vision of a world that embodies mathematical beauty." Early life and education Born in Mineola, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peccei–Quinn Theory
In particle physics, the Peccei–Quinn theory is a well-known, long-standing proposal for the resolution of the strong CP problem formulated by Roberto Peccei and Helen Quinn Helen Rhoda Arnold Quinn (born 19 May 1943) is an Australian-born particle physicist and educator who has made major contributions to both fields. Her contributions to theoretical physics include the Peccei–Quinn theory which implies a corre ... in 1977. The theory introduces a new Anomaly (physics), anomalous symmetry to the Standard Model along with a new scalar field theory, scalar field which spontaneous symmetry breaking, spontaneously breaks the symmetry at low energies, giving rise to an axion that suppresses the problematic CP violation. This model has long since been ruled out by experiments and has instead been replaced by similar invisible axion models which utilize the same mechanism to solve the strong CP problem. Overview Quantum chromodynamics (QCD) has a complicated theta vacuum, vac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold Dark Matter
In cosmology and physics, cold dark matter (CDM) is a hypothetical type of dark matter. According to the current standard model of cosmology, Lambda-CDM model, approximately 27% of the universe is dark matter and 68% is dark energy, with only a small fraction being the ordinary baryonic matter that composes stars, planets, and living organisms. ''Cold'' refers to the fact that the dark matter moves slowly compared to the speed of light, giving it a vanishing equation of state. ''Dark'' indicates that it interacts very weakly with ordinary matter and electromagnetic radiation. Proposed candidates for CDM include weakly interacting massive particles, primordial black holes, and axions, as well as most flavors of neutrinos. History The theory of cold dark matter was originally published in 1982 by James Peebles; while the warm dark matter picture was proposed independently at the same time by J. Richard Bond, Alex Szalay, and Michael Turner; and George Blumenthal, H. Pagel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helen Quinn
Helen Rhoda Arnold Quinn (born 19 May 1943) is an Australian-born particle physicist and educator who has made major contributions to both fields. Her contributions to theoretical physics include the Peccei–Quinn theory which implies a corresponding symmetry of nature(related to matter-antimatter symmetry and the possible source of the dark matter that pervades the universe) and contributions to the search for a unified theory for the three types of particle interactions (strong, electromagnetic, and weak). As Chair of the Board on Science Education of the National Academy of Sciences, Quinn led the effort that produced ''A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas''—the basis for the Next Generation Science Standards adopted by many states. Her honours include the Dirac Medal of the International Center for Theoretical Physics, the Oskar Klein Medal from the Royal Swedish Academy of Sciences, appointment as an Honorary Offic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational
In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force between objects and the Earth. This force is dominated by the combined gravitational interactions of particles but also includes effect of the Earth's rotation. Gravity gives weight to physical objects and is essential to understanding the mechanisms responsible for surface water waves and lunar tides. Gravity also has many important biological functions, helping to guide the growth of plants through the process of gravitropism and influencing the circulation of fluids in multicellular organisms. The gravitational attraction between primordial hydrogen and clumps of dark matter in the early universe caused the hydrogen gas to coalesce, eventually condensing and fusing to form stars. At larger scales this results in galaxies and clusters, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Model
The Standard Model of particle physics is the Scientific theory, theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions – excluding gravity) 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. Although the Standard Model is believed to be theoretically self-consistent and has demonstrated some success in providing experimental predictions, it leaves some physics be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Electric Dipole Moment
The neutron electric dipole moment (nEDM), denoted ''d''n, is a measure for the distribution of positive and negative charge inside the neutron. A nonzero electric dipole moment can only exist if the centers of the negative and positive charge distribution inside the particle do not coincide. So far, no neutron EDM has been found. The current best measured limit for ''d''n is . Theory A permanent electric dipole moment of a fundamental particle violates both Parity (physics), parity (P) and T-symmetry, time reversal symmetry (T). These violations can be understood by examining the neutron's Nucleon magnetic moment, magnetic dipole moment and hypothetical electric dipole moment. Under time reversal, the Magnetic moment, magnetic dipole moment changes its direction, whereas the electric dipole moment stays unchanged. Under parity, the electric dipole moment changes its direction but not the magnetic dipole moment. As the resulting system under P and T is not symmetric with respect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quarks
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'' (electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roberto Peccei
Roberto Daniele Peccei (; January 6, 1942 – June 1, 2020) was a theoretical particle physicist whose principal interests lay in the area of electroweak interactions and in the interface between particle physics and physical cosmology. He was most known for formulating the Peccei–Quinn theory (with Helen Quinn), which attempts to resolve the strong CP problem in particle physics. Peccei was a vice chancellor for research at the University of California, Los Angeles between 2000 and 2010. Early life and education The son of Aurelio Peccei (founder of the Club of Rome), Roberto Peccei was born in 1942 in Torino, Italy. He completed his secondary school in Argentina, and came to the United States in 1958 to pursue his university studies in physics. He obtained a B.S. from MIT in 1962, and M.S. from New York University (NYU) in 1964 and a Ph.D. from the MIT Center for Theoretical Physics in 1969. Career After a brief period of postdoctoral work at the University of Washington ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parity (physics)
In physics, a parity transformation (also called parity inversion) is the flip in the sign of ''one'' spatial coordinate. In three dimensions, it can also refer to the simultaneous flip in the sign of all three spatial coordinates (a point reflection): \mathbf: \beginx\\y\\z\end \mapsto \begin-x\\-y\\-z\end. It can also be thought of as a test for chirality of a physical phenomenon, in that a parity inversion transforms a phenomenon into its mirror image. All fundamental interactions of elementary particles, with the exception of the weak interaction, are symmetric under parity transformation. As established by the Wu experiment conducted at the US National Bureau of Standards by Chinese-American scientist Chien-Shiung Wu, the weak interaction is chiral and thus provides a means for probing chirality in physics. In her experiment, Wu took advantage of the controlling role of weak interactions in radioactive decay of atomic isotopes to establish the chirality of the weak f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axion (brand)
Axion is an American brand of dishwashing liquid product marketed by Colgate-Palmolive. It is available in Asia and Latin America. History Originally, Colgate's ''Axion'' brand was the name of an enzyme pre-soak, to be used before laundering clothes. It was introduced on March 18, 1968. See also * Palmolive - a similar dishwashing liquid produced by C-P for the U.S., Canada and other markets. * Axion An axion () is a hypothetical elementary particle originally theorized in 1978 independently by Frank Wilczek and Steven Weinberg as the Goldstone boson of Peccei–Quinn theory, which had been proposed in 1977 to solve the strong CP problem ... - a hypothetical fundamental particle whose name was inspired by the detergent. References {{Colgate-Palmolive Colgate-Palmolive brands Cleaning products ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
