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Vertex Function
In quantum electrodynamics, the vertex function describes the coupling between a photon and an electron beyond the leading order of perturbation theory (quantum mechanics), perturbation theory. In particular, it is the one particle irreducible correlation function involving the fermion \psi, the antifermion \bar, and the vector potential A. Definition The vertex function \Gamma^\mu can be defined in terms of a functional derivative of the effective action Seff as :\Gamma^\mu = - The dominant (and classical) contribution to \Gamma^\mu is the gamma matrix \gamma^\mu, which explains the choice of the letter. The vertex function is constrained by the symmetries of quantum electrodynamics — Lorentz invariance; gauge invariance or the Photon polarization, transversality of the photon, as expressed by the Ward identity; and invariance under Parity (physics), parity — to take the following form: : \Gamma^\mu = \gamma^\mu F_1(q^2) + \frac F_2(q^2) where \sigma^ = (i/2) [\gamma^, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Electrodynamics
In particle physics, quantum electrodynamics (QED) is the Theory of relativity, relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. QED mathematically describes all phenomenon, phenomena involving electric charge, electrically charged particles interacting by means of exchange of photons and represents the quantum mechanics, quantum counterpart of classical electromagnetism giving a complete account of matter and light interaction. In technical terms, QED can be described as a perturbation theory (quantum mechanics), perturbation theory of the electromagnetic Quantum vacuum state, quantum vacuum. Richard Feynman called it "the jewel of physics" for its precision tests of QED, extremely accurate predictions of quantities like the anomalous magnetic moment of the electron and the Lamb shift of the energy levels of hydrogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ward Identity
Ward may refer to: Division or unit * Hospital ward, a hospital division, floor, or room set aside for a particular class or group of patients, for example the psychiatric ward * Prison ward, a division of a penal institution such as a prison * Ward (electoral subdivision), electoral district or unit of local government * Ward (fortification), part of a castle * Ward (LDS Church), a local congregation of The Church of Jesus Christ of Latter-day Saints * Ward (Vietnam), a type of third-tier subdivision of Vietnam * Wards of Japan, a subdivision of a large city Businesses and organizations * WARD (FM), a radio station (91.9 FM) licensed to serve New Paris, Ohio, United States; see List of radio stations in Ohio * WOUF (AM), a radio station (750 AM) licensed to serve Petoskey, Michigan, United States, which held the call sign WARD from 2008 to 2021 * Warring Adolescents Revenge Division (WARD), organization in ''The Hardy Boys'' graphic novels * Ward Body Works, a school bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridge University Press
Cambridge University Press was the university press of the University of Cambridge. Granted a letters patent by King Henry VIII in 1534, it was the oldest university press in the world. Cambridge University Press merged with Cambridge Assessment to form Cambridge University Press and Assessment under Queen Elizabeth II's approval in August 2021. With a global sales presence, publishing hubs, and offices in more than 40 countries, it published over 50,000 titles by authors from over 100 countries. Its publications include more than 420 academic journals, monographs, reference works, school and university textbooks, and English language teaching and learning publications. It also published Bibles, runs a bookshop in Cambridge, sells through Amazon, and has a conference venues business in Cambridge at the Pitt Building and the Sir Geoffrey Cass Sports and Social Centre. It also served as the King's Printer. Cambridge University Press, as part of the University of Cambridge, was a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wiley-VCH
Wiley-VCH is a German publisher owned by John Wiley & Sons. It was founded in 1921 as Verlag Chemie (meaning "Chemistry Press": VCH stands for ''Verlag Chemie'') by two German learned societies A learned society ( ; also scholarly, intellectual, or academic society) is an organization that exists to promote an academic discipline, profession, or a group of related disciplines such as the arts and sciences. Membership may be open to al .... Later, it was merged into the German Chemical Society (GDCh). In 1991, VCH acquired Akademie Verlag. It has been owned by John Wiley & Sons since 1996. The humanities section of Akademie Verlag and the Akademie brand were sold in 1997 to R. Oldenbourg Verlag, while VCH retained the natural sciences catalog. References External links * Wiley (publisher) Publishing companies of Germany Publishing companies established in 1921 Weinheim German companies established in 1921 {{publish-company-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonoblique Correction
In four-fermion scattering processes of particle physics, a nonoblique correction, also called a direct correction, refers to a radiative correction of type + → + in the electroweak sector of the Standard Model. These corrections are being studied at the CERN LEP collider. Together with the oblique corrections, ''nonoblique corrections'' can be used to constrain models of physics beyond the Standard Model. Classes There are three classes of radiative corrections to these processes: * vacuum polarization corrections, * vertex corrections, and * box corrections. The vertex and box corrections, which depend on the identity of the initial and final state fermions, are referred to as the non-oblique corrections. The vacuum polarization corrections are referred to as oblique corrections, since they only affect the mixing and propagation of the gauge bosons and they do not depend on which type of fermions appear in the initial or final states. Exam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fine-structure Constant
In physics, the fine-structure constant, also known as the Sommerfeld constant, commonly denoted by (the Alpha, Greek letter ''alpha''), is a Dimensionless physical constant, fundamental physical constant that quantifies the strength of the electromagnetic interaction between elementary charged particles. It is a dimensionless quantity (dimensionless physical constant), independent of the system of units used, which is related to the strength of the coupling of an elementary charge ''e'' with the electromagnetic field, by the formula . Its numerical value is approximately , with a relative uncertainty of The constant was named by Arnold Sommerfeld, who introduced it in 1916 Equation 12a, ''"rund 7·" (about ...)'' when extending the Bohr model of the atom. quantified the gap in the fine structure of the spectral lines of the hydrogen atom, which had been measured precisely by Albert A. Michelson, Michelson and Edward W. Morley, Morley in 1887. Why the constant should have t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Julian Schwinger
Julian Seymour Schwinger (; February 12, 1918 – July 16, 1994) was a Nobel Prize-winning American theoretical physicist. He is best known for his work on quantum electrodynamics (QED), in particular for developing a relativistically invariant perturbation theory, and for renormalizing QED to one loop order. Schwinger was a physics professor at several universities. Schwinger is recognized as an important physicist, responsible for much of modern quantum field theory, including a variational approach, and the equations of motion for quantum fields. He developed the first electroweak model, and the first example of confinement in 1+1 dimensions. He is responsible for the theory of multiple neutrinos, Schwinger terms, and the theory of the spin-3/2 field. Biography Early life and career Julian Seymour Schwinger was born in New York City, to Ashkenazi Jewish parents, Belle (née Rosenfeld) and Benjamin Schwinger, a garment manufacturer, who had emigrated from Poland to the Unite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landé G-factor
In physics, the Landé ''g''-factor is a particular example of a ''g''-factor, namely for an electron with both spin and orbital angular momenta. It is named after Alfred Landé, who first described it in 1921. In atomic physics, the Landé ''g''-factor is a multiplicative term appearing in the expression for the energy levels of an atom in a weak magnetic field. The quantum states of electrons in atomic orbitals are normally degenerate in energy, with these degenerate states all sharing the same angular momentum. When the atom is placed in a weak magnetic field, however, the degeneracy is lifted. Description The factor comes about during the calculation of the first-order perturbation in the energy of an atom when a weak uniform magnetic field (that is, weak in comparison to the system's internal magnetic field) is applied to the system. Formally we can write the factor as, :g_J= g_L\frac+g_S\frac. The orbital g_L is equal to 1, and under the approximation g_S = 2 , th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anomalous Magnetic Moment
In quantum electrodynamics, the anomalous magnetic moment of a particle is a contribution of effects of quantum mechanics, expressed by Feynman diagrams with loops, to the magnetic moment of that particle. The ''magnetic moment'', also called ''magnetic dipole moment'', is a measure of the strength of a magnetic source. The "Dirac" magnetic moment, corresponding to tree-level Feynman diagrams (which can be thought of as the classical result), can be calculated from the Dirac equation. It is usually expressed in terms of the g-factor (physics), ''g''-factor; the Dirac equation predicts g = 2. For particles such as the electron, this classical result differs from the observed value by a small fraction of a percent. The difference is the anomalous magnetic moment, denoted a and defined as a = \frac Electron The one-loop contribution to the anomalous magnetic moment—corresponding to the first and largest quantum mechanical correction—of the electron is found by calculating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Strength Renormalization
Field may refer to: Expanses of open ground * Field (agriculture), an area of land used for agricultural purposes * Airfield, an aerodrome that lacks the infrastructure of an airport * Battlefield * Lawn, an area of mowed grass * Meadow, a grassland that is either natural or allowed to grow unmowed and ungrazed * Playing field, used for sports or games Arts and media * In decorative art, the main area of a decorated zone, often contained within a border, often the background for motifs ** Field (heraldry), the background of a shield ** In flag terminology, the background of a flag * ''FIELD'' (magazine), a literary magazine published by Oberlin College in Oberlin, Ohio * ''Field'' (sculpture), by Anthony Gormley Organizations * Field department, the division of a political campaign tasked with organizing local volunteers and directly contacting voters * Field Enterprises, a defunct private holding company ** Field Communications, a division of Field Enterprises * Field Museum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Form Factor (quantum Field Theory)
In elementary particle physics and mathematical physics, in particular in effective field theory, a form factor is a function that encapsulates the properties of a certain particle interaction without including all of the underlying physics, but instead, providing the momentum dependence of suitable matrix elements. It is further measured experimentally in confirmation or specification of a theory—see experimental particle physics. Photon–nucleon example For example, at low energies the interaction of a photon with a nucleon is a very complicated calculation involving interactions between the photon and a sea of quarks and gluons, and often the calculation cannot be fully performed from first principles. Often in this context, form factors are also called " structure functions", since they can be used to describe the structure of the nucleon. However, the generic Lorentz-invariant form of the matrix element for the electromagnetic current interaction is known, : \varepsilon ... [...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] |
