|
Soft SUSY Breaking
In theoretical physics, soft SUSY breaking is type of supersymmetry breaking that does not cause ultraviolet divergences to appear in scalar masses. Overview These terms are relevant operators—i.e. operators whose coefficients have a positive dimension of mass—though there are some exceptions. A model with soft SUSY breaking was proposed in 1981 by Howard Georgi and Savas Dimopoulos. Before this, dynamical models of supersymmetry breaking were being used that suffered from giving rise to color and charge breaking vacua. Soft SUSY breaking decouples the origin of supersymmetry breaking from its phenomenological consequences. In effect, soft SUSY breaking adds explicit symmetry breaking to the supersymmetric Standard Model Lagrangian. The source of SUSY breaking results from a different sector where supersymmetry is broken spontaneously. Divorcing the spontaneous supersymmetry breaking from the supersymmetric Standard Model leads to the notion of mediated supersymmetry bre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Physics
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena. The advancement of science generally depends on the interplay between experimental studies and theory. In some cases, theoretical physics adheres to standards of mathematical rigour while giving little weight to experiments and observations.There is some debate as to whether or not theoretical physics uses mathematics to build intuition and illustrativeness to extract physical insight (especially when normal experience fails), rather than as a tool in formalizing theories. This links to the question of it using mathematics in a less formally rigorous, and more intuitive or heuristic way than, say, mathematical physics. For example, while developing special relativity, Albert Einstein was concerned wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minimal Supersymmetric Standard Model
The Minimal Supersymmetric Standard Model (MSSM) is an extension to the Standard Model that realizes supersymmetry. MSSM is the minimal supersymmetrical model as it considers only "the inimumnumber of new particle states and new interactions consistent with "Reality". Supersymmetry pairs bosons with fermions, so every Standard Model particle has a superpartner yet undiscovered. If discovered, such superparticles could be candidates for dark matter, and could provide evidence for grand unification or the viability of string theory. The failure to find evidence for MSSM using the Large Hadron Collider has strengthened an inclination to abandon it. Background The MSSM was originally proposed in 1981 to stabilize the weak scale, solving the hierarchy problem. The Higgs boson mass of the Standard Model is unstable to quantum corrections and the theory predicts that weak scale should be much weaker than what is observed to be. In the MSSM, the Higgs boson has a fermionic superpartne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auxiliary Field
In physics, and especially quantum field theory, an auxiliary field is one whose equations of motion admit a single solution. Therefore, the Lagrangian describing such a field A contains an algebraic quadratic term and an arbitrary linear term, while it contains no kinetic terms (derivatives of the field): :\mathcal_\text = \frac(A, A) + (f(\varphi), A). The equation of motion for A is :A(\varphi) = -f(\varphi), and the Lagrangian becomes :\mathcal_\text = -\frac(f(\varphi), f(\varphi)). Auxiliary fields generally do not propagate, and hence the content of any theory can remain unchanged in many circumstances by adding such fields by hand. If we have an initial Lagrangian \mathcal_0 describing a field \varphi, then the Lagrangian describing both fields is :\mathcal = \mathcal_0(\varphi) + \mathcal_\text = \mathcal_0(\varphi) - \frac\big(f(\varphi), f(\varphi)\big). Therefore, auxiliary fields can be employed to cancel quadratic terms in \varphi in \mathcal_0 and linearize the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Higgsino
In particle physics, for models with N=1 supersymmetry a higgsino, symbol , is the superpartner of the Higgs field. A higgsino is a Dirac fermionic field with spin and it refers to a weak isodoublet with hypercharge half under the Standard Model gauge symmetries. After electroweak symmetry breaking higgsino fields linearly mix with U(1) and SU(2) gauginos leading to four neutralinos and two charginos that refer to physical particles. While the two charginos are charged Dirac fermions (plus and minus each), the neutralinos are electrically neutral Majorana fermions. In an R-parity-conserving version of the Minimal Supersymmetric Standard Model, the lightest neutralino typically becomes the lightest supersymmetric particle (LSP). The LSP is a particle physics candidate for the dark matter of the universe since it cannot decay to particles with lighter mass. A neutralino LSP, depending on its composition can be bino, wino or higgsino dominated in nature and can have different zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D-term
In theoretical physics, one often analyzes theories with supersymmetry in which D-terms play an important role. In four dimensions, the minimal N=1 supersymmetry may be written using a superspace. This superspace involves four extra fermionic coordinates \theta^1,\theta^2,\bar\theta^1,\bar\theta^2, transforming as a two-component spinor and its conjugate. Every superfield, i.e. a field that depends on all coordinates of the superspace, may be expanded with respect to the new fermionic coordinates. The generic kind of superfields, typically a vector superfield, indeed depend on all these coordinates. The last term in the corresponding expansion, namely D \theta^1\theta^2\bar\theta^1\bar\theta^2, is called the D-term. Manifestly supersymmetric Lagrangians may also be written as integrals over the whole superspace. Some special terms, such as the superpotential, may be written as integrals over \thetas only, which are known as F-terms, and should be contrasted with the present D-term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supermultiplet
In theoretical physics, a supermultiplet is a representation of a supersymmetry algebra. Then a superfield is a field on superspace which is valued in such a representation. Naïvely, or when considering flat superspace, a superfield can simply be viewed as a function on superspace. Formally, it is a section of an associated supermultiplet bundle. Phenomenologically, superfields are used to describe particles. It is a feature of supersymmetric field theories that particles form pairs, called superpartners where bosons are paired with fermions. These supersymmetric fields are used to build supersymmetric quantum field theories, where the fields are promoted to operators. History Superfields were introduced by Abdus Salam and J. A. Strathdee in their 1974 articlSupergauge Transformations Operations on superfields and a partial classification were presented a few months later by Sergio Ferrara, Julius Wess and Bruno Zumino iSupergauge Multiplets and Superfields Naming and class ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hidden Sector
In particle physics, the hidden sector, also known as the dark sector, is a hypothetical collection of yet-unobserved quantum fields and their corresponding hypothetical particles. The interactions between the hidden sector particles and the Standard Model particles are weak, indirect, and typically mediated through gravity or other new particles. Examples of new hypothetical mediating particles in this class of theories include the dark photon, sterile neutrino, and axion. In many cases, hidden sectors include a new gauge group that is independent from the Standard Model gauge group. The hidden sectors are commonly predicted by the models from string theory. They may be relevant as a source of dark matter and supersymmetry breaking, solving the Muon g-2 anomaly and beryllium-8 decay anomaly. } See also * Fifth force * Dark energy * Dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holomorphic Function
In mathematics, a holomorphic function is a complex-valued function of one or more complex variables that is complex differentiable in a neighbourhood of each point in a domain in complex coordinate space . The existence of a complex derivative in a neighbourhood is a very strong condition: it implies that a holomorphic function is infinitely differentiable and locally equal to its own Taylor series (''analytic''). Holomorphic functions are the central objects of study in complex analysis. Though the term ''analytic function'' is often used interchangeably with "holomorphic function", the word "analytic" is defined in a broader sense to denote any function (real, complex, or of more general type) that can be written as a convergent power series in a neighbourhood of each point in its domain. That all holomorphic functions are complex analytic functions, and vice versa, is a major theorem in complex analysis. Holomorphic functions are also sometimes referred to as ''regular fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superpotential
In theoretical physics, the superpotential is a function in supersymmetric quantum mechanics. Given a superpotential, two "partner potentials" are derived that can each serve as a potential in the Schrödinger equation. The partner potentials have the same spectrum, apart from a possible eigenvalue of zero, meaning that the physical systems represented by the two potentials have the same characteristic energies, apart from a possible zero-energy ground state. One-dimensional example Consider a one-dimensional, non-relativistic particle with a two state internal degree of freedom called "spin". (This is not quite the usual notion of spin encountered in nonrelativistic quantum mechanics, because "real" spin applies only to particles in three-dimensional space.) Let ''b'' and its Hermitian adjoint ''b''† signify operators which transform a "spin up" particle into a "spin down" particle and vice versa, respectively. Furthermore, take ''b'' and ''b''† to be normalized such that the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersymmetry Breaking
In particle physics, supersymmetry breaking is the process to obtain a seemingly non-supersymmetric physics from a supersymmetric theory which is a necessary step to reconcile supersymmetry with actual experiments. It is an example of spontaneous symmetry breaking. In supergravity, this results in a slightly modified counterpart of the Higgs mechanism where the gravitinos become massive. Supersymmetry breaking occurs at supersymmetry breaking scale. The superpartners, whose mass would otherwise be equal to the mass of the regular particles in the absence of the SUSY breaking, become much heavier. In the domain of applicability of stochastic differential equations including, e.g, classical physics, spontaneous supersymmetry breaking encompasses such nonlinear dynamical phenomena as chaos theory, chaos, turbulence, pink noise, etc. Supersymmetry breaking scale In particle physics, supersymmetry breaking scale is the energy scale where supersymmetry breaking takes place. If sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersymmetry
In a supersymmetric theory the equations for force and the equations for matter are identical. In theoretical and mathematical physics, any theory with this property has the principle of supersymmetry (SUSY). Dozens of supersymmetric theories exist. Supersymmetry is a spacetime symmetry between two basic classes of particles: bosons, which have an integer-valued spin and follow Bose–Einstein statistics, and fermions, which have a half-integer-valued spin and follow Fermi–Dirac statistics. In supersymmetry, each particle from one class would have an associated particle in the other, known as its superpartner, the spin of which differs by a half-integer. For example, if the electron exists in a supersymmetric theory, then there would be a particle called a ''"selectron"'' (superpartner electron), a bosonic partner of the electron. In the simplest supersymmetry theories, with perfectly " unbroken" supersymmetry, each pair of superpartners would share the same mass and intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explicit Symmetry Breaking
In theoretical physics, explicit symmetry breaking is the breaking of a symmetry of a theory by terms in its defining equations of motion (most typically, to the Lagrangian or the Hamiltonian) that do not respect the symmetry. Usually this term is used in situations where these symmetry-breaking terms are small, so that the symmetry is approximately respected by the theory. An example is the spectral line splitting in the Zeeman effect, due to a magnetic interaction perturbation in the Hamiltonian of the atoms involved. Explicit symmetry breaking differs from spontaneous symmetry breaking. In the latter, the defining equations respect the symmetry but the ground state (vacuum) of the theory breaks it. Explicit symmetry breaking is also associated with electromagnetic radiation. A system of accelerated charges results in electromagnetic radiation when the geometric symmetry of the electric field in free space is explicitly broken by the associated electrodynamic structure under tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
