Category:Symmetry

From Eurêka

Contents 1 Symmetry 2 Broken Symmetry 3 Supersymmetry 4 Supersymmetric Research

Symmetry

Symmetry State of a system such that it has a significant quantity that remains invariant after a transformation. More generally, an apt or pleasing proposition based upon such a state.

1. Global symmetry Symmetry that applies everywhere.
2. Local symmetry Symmetry that applies to a given system at a given place and time.

Symmetry group Mathematical group with a common property that unites its members and evinces a symmetry.

1. Group Ensemble of mathematical entities linked by symmetry.

Isospin Symmetry first noted in the 1930s in that the strong force is invariant under transformation of electrical charge.

1. Eightfold way Symmetrical arrangement of hadrons (particles that respond to a strong force). It has achieved experimental verification when a previously undetected baryon, the existence of which it predicted, the omega minus, was identified experimentally.
2. Special unitary group (SU(3)) One of a set of symmetry groups identified by the French mathematician Elie-Joseph Cartan.

Note : The number (3) means that the symmetry operates in three-dimensional internal space.

Symmetry breaking Loss of symmetry in a transformation.

1. Higgs field Mechanism operating in symmetry-breaking events. In electroweak theory, the Higgs field is said to have imparted mass to the W and Z particles.

Broken Symmetry

Broken symmetry In particle physics, a state in which traces of earlier symmetry may be discerned. A broken symmetry condition differs from chaos in that its parts can in theory be united in a symmetrical whole.

Asymmetry Violation of symmetry.

Gauge field theory Account of forces that views them as arising from broken symmetry. The theory has been described as a revolution in the same class as relativity and quantum physics.

Conservation of parity (Parity conservation) If the wave function describing the initial state of a system has even/odd parity, the wave function describing the final state has even/odd parity. It is violated by the weak interactions.

Symmetry in parity Physics in the mirror world would be identical to our own.

1. Parity violation Symmetry in parity collapsed when Tsung-Dao Lee and Chen N. Ning Yang discovered the assumed symmetry of parity in particles did not exist, that when short-lived particles called K mesons (kaons) decayed their transformations violate parity symmetry. The were awarded the Nobel Prize in Physics, 1957.
2. CPT Total package of charge, parity and time, a combination of interlocking components.
3. Time reverse symmetry Compensation of time to accommodate changes in charge and parity.
4. Backward in time Particle moving from one place to another forward in time which involves 3 fundamental transformations: the reversal of electrical charge (C), which changes particles into antiparticles and vice versa; parity reversal (P), the mirror reversal of every dimension in the particle (turning it inside out); and time reversal (T).
5. Time reversal experiment Detectors at CERN, near Geneva, measured the oscillations of kaons into antikaons, and vice versa, as the fleeting particles flew away from their point of origin. If time were perfectly symmetrical, the rates at which kaons and antikaons are transformed into each other should be precisely equal. The experiment showed that the rate of antikaons turn into kaons is higher than the time-reverse process in which kaons become antikaons.
6. Left-handed bias Universe is classified as left-handed. Experiments show particles react differently in a mirror world with left, right, up and down reversed.

Wu Chinese-American physicist Chien-Shiung Wu (1912-?), who had moved from China to US 1936, confirmed experimentally that parity is not conserved by the weak nuclear force 1963.

Charge-parity violation (CP violation) Difference in the decay rates of matter and antimatter subatomic particles, phenomenon detected in 1964.

1. “K” meson CP violation Discovery of CP violation while experimenting with the “K” meson (kaon) and its antimatter equivalent by researchers based at Brookhaven NL in New York, for which they were awarded the Nobel Prize.
2. “B” meson CP violation Differences in decay rates of the B mesons subatomic particles and its antimatter counterparts, discovered by an international team at Stanford University announced July 2001.

Supersymmetry

Supersymmetry Class of theories that seek to identify symmetrical relationships linking fermions and bosons, i.e. particles of half-spin life. These theories, which invoke a plethora of new particles and new terms, are based on the idea that there is an underlying similarity between force-carrying bosoms and material fermions. It may help to provide a grand unified theory, for example, helping astrophysicists looking for dark matter which fills the empty universe. Supersymmetry has yet to be found in nature, but theorists frequently invoke its powers.

(1) Symmetry relating fermions and bosons. If supersymmetry is a true symmetry of nature, then every “ordinary” particle has a corresponding superpartner which differs in spin by half a unit.

(2) Symmetry principle that relates the properties of particles with a whole number amount of spin (bosons) to those with half a whole (odd) number amount of spin (fermions).

(3) Symmetry that relates the fermions (fractional spin particles) to the bosons (elementary particles with integral spin).

(4) Class of theories that seek to identify symmetrical relationships linking fermions and bosons - i.e., particles of half integer spin, like electrons, protons, and neutrinos, with those of integral spin, like photons and gluons. If attainable, a fully realized supersymmetry theory would provide a unified account of all four fundamental forces, and might well shed light on the very early evolution of the Universe as well.

(5) Mathematical property of some theories of physics proposing that every particle of integer spin (intrinsic angular momentum) has a partner of half integer spin. For example, the photon, which is the particle of light, has a spin of 1 unit. Its hypothesized super symmetric partner is called the photino, which would have a spin of 1/2 units.

(6) Invariance principle that aspires to place fermions and bosons on an equal footing.

(7) Hypothetical symmetry that describes nature and says that even though fermions and bosons seem to us to be very different in their properties and their roles, in the theory itself they appear in a symmetric way. If supersymmetry is indeed realized in nature, then every particle has a superpartner.

1. Superpartners Particles whose spins differ by 1/2 unit and that are paired by supersymmetry.

Supersymmetric particles New particles posited by supersymmetry that solve many of the problems of the Standard Model which theorists believe has logical and aesthetic flaws and that its complicated structure is unlikely to represent natural law at its most fundamental level.

1. Gravitino Hypothetical force-carry particle predicted by supersymmetry theories. The gravitino’s spin would be 1/2. Its mass is unknown.
2. Photino Supersymmetric partner of the photon.
3. Slepton Supersymmetric partner of any of the lepton.
4. Wino Supersymmetric partner of the W boson.
5. Zino Supersymmetric partner of the Z boson.

Unified supersymmetric theory Theory that may gather all particles and all fields under the umbrella of a single set of equations.

Superunified theory Hypothetical theory that presumably would show how all four fundamental forces of nature functioned as a single force in the extremely early Universe. The best current candidates for such a potential achievement are thought to be supersymmetry and string theory.

Supersymmetric Research

E821 Brookhaven experiment Muons created by the Alternating Gradient Synchroton were injected into a powerful magnetic field and the frequency of their wobble was measured to great precision.

1. Wobble frequency Scientists have known for decades that this frequency is affected by the properties of space itself which is a sea of virtual particles. The Standard Model shows how to calculate the effect that all known particles in that sea should have on the wobble frequency. But E821 experiment measurements differ from the predictions, suggesting that previously unknown particles are also lurking in the subatomic sea.
   1. Precesses Wobbles caused by spin, a quantum-mechanical property, that is shared by muons and other particles.
   2. Wobble frequency measurement To make the measurements, researchers relied on the fact that if the spin axis is not vertical, it precesses, just as muons do in a strong magnetic field.