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Little Higgs
In particle physics, little Higgs models are based on the idea that the Higgs boson is a pseudo-Goldstone boson arising from some global symmetry breaking at a TeV energy scale. The goal of little Higgs models is to use the spontaneous breaking of such approximate global symmetries to stabilize the mass of the Higgs boson(s) responsible for electroweak symmetry breaking. The little Higgs models predict a naturally-light Higgs particle. Loop cancellation The main idea behind the little Higgs models is that the one-loop contribution to the tachyonic Higgs boson mass coming from the top quark cancels.Other one-loop contributions are small enough that they don't really matter: The Yukawa coupling of the top quark is enormous because of its huge mass, and all the other fermions' Yukawa couplings and gauge couplings are negligible by comparison. The simplified reason for that cancellation is that a loop's contribution is proportional to the coupling constant of one of the SU(2) groups ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Physics
Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons, while the study of combinations of protons and neutrons is called nuclear physics. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) and bosons (force-carrying particles). There are three Generation (particle physics), generations of fermions, although ordinary matter is made only from the first fermion generation. The first generation consists of Up quark, up and down quarks which form protons and neutrons, and electrons and electron neutrinos. The three fundamental interactions known to be mediated by bosons are electromagnetism, the weak interaction, and the strong interaction. Quark, Quarks cannot exist on their own but form hadrons. Hadrons that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Product Of Groups
In mathematics, specifically in group theory, the direct product is an operation that takes two groups and and constructs a new group, usually denoted . This operation is the group-theoretic analogue of the Cartesian product of sets and is one of several important notions of direct product in mathematics. In the context of abelian groups, the direct product is sometimes referred to as the direct sum, and is denoted G \oplus H. Direct sums play an important role in the classification of abelian groups: according to the fundamental theorem of finite abelian groups, every finite abelian group can be expressed as the direct sum of cyclic groups. Definition Given groups (with operation ) and (with operation ), the direct product is defined as follows: The resulting algebraic object satisfies the axioms for a group. Specifically: ;Associativity: The binary operation on is associative. ;Identity: The direct product has an identity element, namely , where is the identi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Composite Higgs Models
In particle physics, composite Higgs models (CHM) are speculative extensions of the Standard Model (SM) where the Higgs boson is a bound state of new strong interactions. These scenarios are models for physics beyond the SM presently tested at the Large Hadron Collider (LHC) in Geneva. In all composite Higgs models the Higgs boson is not an elementary particle (or point-like) but has finite size, perhaps around 10−18 meters. This dimension may be related to the Fermi scale (100 GeV) that determines the strength of the weak interactions such as in β-decay, but it could be significantly smaller. Microscopically the composite Higgs will be made of smaller constituents in the same way as nuclei are made of protons and neutrons. History Often referred to as "natural" composite Higgs models, CHMs are constructions that attempt to alleviate fine-tuning or "naturalness" problem of the Standard Model. These typically engineer the Higgs boson as a naturally light pseudo-Goldstone boso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ann Nelson
Ann Elizabeth Nelson (April 29, 1958 – August 4, 2019) was an American particle physicist and professor of physics in the Particle Theory Group at the University of Washington from 1994 until her death. Nelson received a Guggenheim Fellowship in 2004, and she was elected to the American Academy of Arts and Sciences in 2011 and the National Academy of Sciences in 2012. She was a recipient of the 2018 J. J. Sakurai Prize for Theoretical Particle Physics, presented annually by the American Physical Society and considered one of the most prestigious prizes in physics. Education Born in Baton Rouge, Louisiana, Nelson earned her Bachelor of Science degree at Stanford University in 1980, and her Ph.D. degree at Harvard University under the supervision of Howard Georgi in 1984. Career After a post doctoral fellowship at the Harvard Society of Fellows from 1984-1987, Nelson became an assistant professor at Stanford University in 1987. In 1990 Nelson moved to UC San Diego, and then ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Howard Georgi
Howard Mason Georgi III (born January 6, 1947 in San Bernardino) 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 (1973–1976) 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nima Arkani-Hamed
Nima Arkani-Hamed (; born April 5, 1972) is an Iranian-American-Canadian"Curriculum Vita, updated 4-17-15" sns.ias.edu; accessed December 4, 2015. , with interests in , |
Extra Dimensions
In physics, extra dimensions or extra-dimensional spaces are proposed as additional space or time dimensions beyond the (3 + 1) typical of observed spacetime — meaning 5-dimensional or higher. such as the first attempts based on the Kaluza–Klein theory. Among theories proposing extra dimensions are: * Large extra dimension, mostly motivated by the ADD model, by Nima Arkani-Hamed, Savas Dimopoulos, and Gia Dvali in 1998, in an attempt to solve the hierarchy problem. This theory requires that the fields of the Standard Model are confined to a four-dimensional membrane, while gravity propagates in several additional spatial dimensions that are large compared to the Planck scale.For a pedagogical introduction, see * Warped extra dimensions, such as those proposed by the Randall–Sundrum model (RS), based on warped geometry where the universe is a five-dimensional anti-de Sitter space and the elementary particles except for the graviton are localized on a (3&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimension
In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coordinate is needed to specify a point on itfor example, the point at 5 on a number line. A surface, such as the boundary of a cylinder or sphere, has a dimension of two (2D) because two coordinates are needed to specify a point on itfor example, both a latitude and longitude are required to locate a point on the surface of a sphere. A two-dimensional Euclidean space is a two-dimensional space on the plane. The inside of a cube, a cylinder or a sphere is three-dimensional (3D) because three coordinates are needed to locate a point within these spaces. In classical mechanics, space and time are different categories and refer to absolute space and time. That conception of the world is a four-dimensional space but not the one that w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gauge Group
A gauge group is a group of gauge symmetries of the Yang–Mills gauge theory of principal connections on a principal bundle. Given a principal bundle P\to X with a structure Lie group G, a gauge group is defined to be a group of its vertical automorphisms, that is, its group of bundle automorphisms. This group is isomorphic to the group G(X) of global sections of the associated group bundle \widetilde P\to X whose typical fiber is a group G which acts on itself by the adjoint representation. The unit element of G(X) is a constant unit-valued section g(x)=1 of \widetilde P\to X. At the same time, gauge gravitation theory exemplifies field theory on a principal frame bundle whose gauge symmetries are general covariant transformations which are not elements of a gauge group. In the physical literature on gauge theory, a structure group of a principal bundle often is called the gauge group. In quantum gauge theory, one considers a normal subgroup G^0(X) of a gauge group ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Higgs Boson
The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the excited state, quantum excitation of the Higgs field, one of the field (physics), fields in particle physics theory. In the Standard Model, the Higgs particle is a massive scalar boson that Coupling (physics), couples to (interacts with) particles whose mass arises from their interactions with the Higgs Field, has zero Spin (physics), spin, even (positive) Parity (physics), parity, no electric charge, and no color charge, colour charge. It is also very unstable, particle decay, decaying into other particles almost immediately upon generation. The Higgs field is a scalar field with two neutral and two electrically charged components that form a complex doublet (physics), doublet of the weak isospin SU(2) symmetry. Its "Spontaneous symmetry breaking#Sombrero potential, sombrero potential" leads it to take a nonzero value everywhere (inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimensional Deconstruction
In theoretical physics, dimensional deconstruction is a method to construct ''4''-dimensional theories that behave as higher-dimensional theories in a certain range of higher energies. The resulting theory is a gauge theory whose gauge group is a direct product of many copies of the same group; each copy may be interpreted as the gauge group located at a particular point along a new, discrete, "deconstructed" ''(d+1)''st dimension. The spectrum of matter fields is a set of bifundamental representations expressed by a quiver diagram that is analogous to lattices in lattice gauge theory. "Deconstruction" in physics was introduced by Nima Arkani-Hamed, Andy Cohen and Howard Georgi, and independently by Christopher T. Hill, Stefan Pokorski and Jing Wang. Deconstruction is a lattice approximation to the real space of extra dimensions, while maintaining the full gauge symmetries and yields the low energy effective description of the physics. This leads to a rationale for extensions o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
