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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 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) 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] |
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] |
C-symmetry
In physics, charge conjugation is a transformation that switches all particles with their corresponding antiparticles, thus changing the sign of all charges: not only electric charge but also the charges relevant to other forces. The term C-symmetry is an abbreviation of the phrase "charge conjugation symmetry", and is used in discussions of the symmetry of physical laws under charge-conjugation. Other important discrete symmetries are P-symmetry (parity) and T-symmetry (time reversal). These discrete symmetries, C, P and T, are symmetries of the equations that describe the known fundamental forces of nature: electromagnetism, gravity, the strong and the weak interactions. Verifying whether some given mathematical equation correctly models nature requires giving physical interpretation not only to continuous symmetries, such as motion in time, but also to its discrete symmetries, and then determining whether nature adheres to these symmetries. Unlike the continuous symmetri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudo-Nambu–Goldstone Boson
In particle physics, chiral symmetry breaking generally refers to the dynamical spontaneous breaking of a chiral symmetry associated with massless fermions. This is usually associated with a gauge theory such as quantum chromodynamics, the quantum field theory of the strong interaction, and it also occurs through the Brout-Englert-Higgs mechanism in the electroweak interactions of the standard model. This phenomenon is analogous to magnetization and superconductivity in condensed matter physics - where, for example, chiral symmetry breaking is the mechanism by which disordered 3D magnetic systems have a finite transition temperature. The basic idea was introduced to particle physics by Yoichiro Nambu, in particular, in the Nambu–Jona-Lasinio model, which is a solvable theory of composite bosons that exhibits dynamical spontaneous chiral symmetry when a 4-fermion coupling constant becomes sufficiently large. Nambu was awarded the 2008 Nobel prize in physics "for the discovery of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quanta Magazine
''Quanta Magazine'' is an editorially independent online publication of the Simons Foundation covering developments in physics, mathematics, biology and computer science. History ''Quanta Magazine'' was initially launched as ''Simons Science News'' in October 2012, but it was renamed to its current title in July 2013. It was founded by the former ''New York Times'' journalist Thomas Lin, who was the magazine's editor-in-chief until 2024. The two deputy editors are John Rennie and Michael Moyer, formerly of ''Scientific American'', and the art director is Samuel Velasco. In 2024, Samir Patel became the magazine's second editor in chief. Content The articles in the magazine are freely available to read online. ''Scientific American'', ''Wired'', ''The Atlantic'', and ''The Washington Post'', as well as international science publications like '' Spektrum der Wissenschaft'', have reprinted articles from the magazine. In November 2018, MIT Press The MIT Press is the uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The New York Times
''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of the longest-running newspapers in the United States, the ''Times'' serves as one of the country's Newspaper of record, newspapers of record. , ''The New York Times'' had 9.13 million total and 8.83 million online subscribers, both by significant margins the List of newspapers in the United States, highest numbers for any newspaper in the United States; the total also included 296,330 print subscribers, making the ''Times'' the second-largest newspaper by print circulation in the United States, following ''The Wall Street Journal'', also based in New York City. ''The New York Times'' is published by the New York Times Company; since 1896, the company has been chaired by the Ochs-Sulzberger family, whose current chairman and the paper's publ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axial Current
In particle physics, the axial current, also denoted the ''pseudo-vector'' or ''chiral'' current, is the conserved current associated to the chiral symmetry or axial symmetry of a system. Origin According to Noether's theorem, each symmetry of a system is associated a conserved quantity. For example, the rotational invariance of a system implies the conservation of its angular momentum, or spacetime invariance implies the conservation of energy–momentum. In quantum field theory, internal symmetries also result in conserved quantities. For example, the U(1) gauge transformation of QED implies the conservation of the electric charge. Likewise, if a theory possesses an internal chiral or axial symmetry, there will be a conserved quantity, which is called the ''axial charge''. Further, just as the motion of an electrically charged particle produces an electric current, a moving axial charge constitutes an axial current. Definition The axial current resulting from the motion of ... [...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] |
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] |
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] |
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] |
