|
Georgi–Jarlskog Mass Relation
In grand unified theories of the SU(5) or SO(10) type, there is a mass relation predicted between the electron and the down quark, the muon and the strange quark and the tau lepton and the bottom quark called the Georgi–Jarlskog mass relations. The relations were formulated by Howard Georgi and Cecilia Jarlskog Cecilia Jarlskog (born in 1941) is a Swedish theoretical physicist, working mainly on elementary particle physics. Jarlskog obtained her doctorate in 1970 in theoretical particle physics at the Technical University of Lund. She is known for her .... At GUT scale, these are sometimes quoted as: :m_ \approx \frac m_ :m_ \approx 3 m_ :m_ \approx m_ In the same paper it is written that: :m_ \approx \frac m_d :m_ \approx \frac m_s :m_ \approx \frac m_b Meaning that: :m_d \approx 9 m_e error = 5\% :m_s \approx m_ error = 21\% :m_b \approx 3 m_ error = 26\% References Grand Unified Theory {{particle-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grand Unification Theory
A Grand Unified Theory (GUT) is a model in particle physics in which, at high energies, the three gauge interactions of the Standard Model comprising the electromagnetic, weak, and strong forces are merged into a single force. Although this unified force has not been directly observed, many GUT models theorize its existence. If unification of these three interactions is possible, it raises the possibility that there was a grand unification epoch in the very early universe in which these three fundamental interactions were not yet distinct. Experiments have confirmed that at high energy the electromagnetic interaction and weak interaction unify into a single electroweak interaction. GUT models predict that at even higher energy, the strong interaction and the electroweak interaction will unify into a single electronuclear interaction. This interaction is characterized by one larger gauge symmetry and thus several force carriers, but one unified coupling constant. Unifying ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron's mass is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum ( spin) of a half-integer value, expressed in units of the reduced Planck constant, . Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: They can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Down Quark
The down quark or d quark (symbol: d) is the second-lightest of all quarks, a type of elementary particle, and a major constituent of matter. Together with the up quark, it forms the neutrons (one up quark, two down quarks) and protons (two up quarks, one down quark) of atomic nuclei. It is part of the first generation of matter, has an electric charge of − ''e'' and a bare mass of . Like all quarks, the down quark is an elementary fermion with spin , and experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and strong interactions. The antiparticle of the down quark is the down antiquark (sometimes called ''antidown quark'' or simply ''antidown''), which differs from it only in that some of its properties have equal magnitude but opposite sign. Its existence (along with that of the up and strange quarks) was postulated in 1964 by Murray Gell-Mann and George Zweig to explain the Eightfold Way classification scheme of hadro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muon
A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of , but with a much greater mass. It is classified as a lepton. As with other leptons, the muon is not thought to be composed of any simpler particles; that is, it is a fundamental particle. The muon is an unstable subatomic particle with a mean lifetime of , much longer than many other subatomic particles. As with the decay of the non-elementary neutron (with a lifetime around 15 minutes), muon decay is slow (by subatomic standards) because the decay is mediated only by the weak interaction (rather than the more powerful strong interaction or electromagnetic interaction), and because the mass difference between the muon and the set of its decay products is small, providing few kinetic degrees of freedom for decay. Muon decay almost always produces at least three particles, which must include an electron o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strange Quark
The strange quark or s quark (from its symbol, s) is the third lightest of all quarks, a type of elementary particle. Strange quarks are found in subatomic particles called hadrons. Examples of hadrons containing strange quarks include kaons (), strange D mesons (), Sigma baryons (), and other strange particles. According to the IUPAP, the symbol s is the official name, while "strange" is to be considered only as a mnemonic. The name sideways has also been used because the s quark has an I value of 0 while the u ("up") and d ("down") quarks have values of + and − respectively. Along with the charm quark, it is part of the second generation of matter. It has an electric charge of − ''e'' and a bare mass of . Like all quarks, the strange quark is an elementary fermion with spin , and experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and strong interactions. The antiparticle of the strange quark is the strange ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Lepton
The tau (), also called the tau lepton, tau particle, tauon or tau electron, is an elementary particle similar to the electron, with negative electric charge and a spin of . Like the electron, the muon, and the three neutrinos, the tau is a lepton, and like all elementary particles with half-integer spin, the tau has a corresponding antiparticle of opposite charge but equal mass and spin. In the tau's case, this is the "antitau" (also called the ''positive tau''). Tau particles are denoted by the symbol and the antitaus by . Tau leptons have a lifetime of and a mass of (compared to for muons and for electrons). Since their interactions are very similar to those of the electron, a tau can be thought of as a ''much'' heavier version of the electron. Because of their greater mass, tau particles do not emit as much bremsstrahlung radiation as electrons; consequently they are potentially much more highly penetrating than electrons. Because of its short lifetime, the range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bottom Quark
The bottom quark or b quark, also known as the beauty quark, is a third-generation heavy quark with a charge of − ''e''. All quarks are described in a similar way by electroweak and quantum chromodynamics, but the bottom quark has exceptionally low rates of transition to lower-mass quarks. The bottom quark is also notable because it is a product in almost all top quark decays, and is a frequent decay product of the Higgs boson. Name and history The bottom quark was first described theoretically in 1973 by physicists Makoto Kobayashi and Toshihide Maskawa to explain CP violation. The name "bottom" was introduced in 1975 by Haim Harari. The bottom quark was discovered in 1977 by the Fermilab E288 experiment team led by Leon M. Lederman, when collisions produced bottomonium. Kobayashi and Maskawa won the 2008 Nobel Prize in Physics for their explanation of CP-violation. While the name "beauty" is sometimes used, "bottom" became the predominant usage by analogy of "to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Howard Georgi
Howard Mason Georgi III (born January 6, 1947) is an American theoretical physicist and the Mallinckrodt Professor of Physics and Harvard College Professor at Harvard University. He is also Director of Undergraduate Studies in Physics. He was Co-Master and then Faculty Dean of Leverett House with his wife, Ann Blake Georgi, from 1998 to 2018. His early work was in Grand Unification and gauge coupling unification within SU(5) and SO(10) groups (see Georgi–Glashow model). Education Georgi graduated from Pingry School in 1964, graduated from Harvard College in 1967 and obtained his Ph.D. from Yale University in 1971. He was Junior Fellow in the Harvard Society of Fellows from 1973–76 and a Senior Fellow from 1982-1998. Career In early 1974 Georgi (with Sheldon Glashow) published the first grand unified theory (GUT), the Minimal SU(5) Georgi–Glashow model. Georgi independently (alongside Harald Fritzsch and Peter Minkowski) published a minimal SO(10) GUT model in 1974. Geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cecilia Jarlskog
Cecilia Jarlskog (born in 1941) is a Swedish theoretical physicist, working mainly on elementary particle physics. Jarlskog obtained her doctorate in 1970 in theoretical particle physics at the Technical University of Lund. She is known for her work on CP violation in the electroweak sector of the Standard Model, introducing what is known as the Jarlskog invariant, and for her work on grand unified theories (see Georgi–Jarlskog mass relation). Research interests Cecilia Jarlskog is mainly known for her study and expertise in theoretical particle physics. Her studies include research on the ways that sub-atomic and electronic constituents of matter cohere or lose their symmetry, matter and antimatter asymmetry, mathematical physics, neutrino physics, and grand unification. The Jarlskog invariant or rephasing-invariant CP violation parameter, is an invariant quantity in particle physics, which is in the order of ±2.8 x 10−5. This parameter is related to the unitarity condi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physics Letters B
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." Physics is one of the most fundamental scientific disciplines, with its main goal being to understand how the universe behaves. "Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MSbar Scheme
In quantum field theory, the minimal subtraction scheme, or MS scheme, is a particular renormalization scheme used to absorb the infinities that arise in perturbative calculations beyond leading order, introduced independently by Gerard 't Hooft and Steven Weinberg in 1973. The MS scheme consists of absorbing only the divergent part of the radiative corrections into the counterterms. In the similar and more widely used modified minimal subtraction, or MS-bar scheme (\overline), one absorbs the divergent part plus a universal constant that always arises along with the divergence in Feynman diagram calculations into the counterterms. When using dimensional regularization __NOTOC__ In theoretical physics, dimensional regularization is a method introduced by Giambiagi and Bollini as well as – independently and more comprehensively – by 't Hooft and Veltman for regularizing integrals in the evaluation of Fe ..., i.e. d^4 p \to \mu^ d^d p, it is implemented by rescalin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
On-shell Scheme
In quantum field theory, and especially in quantum electrodynamics, the interacting theory leads to infinite quantities that have to be absorbed in a renormalization procedure, in order to be able to predict measurable quantities. The renormalization scheme can depend on the type of particles that are being considered. For particles that can travel asymptotically large distances, or for low energy processes, the on-shell scheme, also known as the physical scheme, is appropriate. If these conditions are not fulfilled, one can turn to other schemes, like the minimal subtraction scheme (MS scheme). Fermion propagator in the interacting theory Knowing the different propagators is the basis for being able to calculate Feynman diagrams which are useful tools to predict, for example, the result of scattering experiments. In a theory where the only field is the Dirac field, the Feynman propagator reads : \langle 0 , T(\psi(x)\bar(0)), 0 \rangle =iS_F(x) = \int \frac\frac where T is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_representation_of_fermions.png "Click for more on -> Grand Unification Theory")
