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Propagator (field theory)

The probability amplitude for a particle to move or propagate to some new point of space and time when its amplitude at some point of origination is known. The propagator occurs as an important part of the probability in reactions and interactions in all branches of modern physics. Its properties are best described in the framework of quantum field theory for relativistic particles, where it is written in terms of energy and momentum. Concrete examples for electron-proton and proton-proton scattering are provided in the illustration. The amplitude for these processes contains the propagators for the exchanged proton and meson, which actually specify the dominant part of the probability of each process when the scattering occurs at small angles. In similar fashion, for any electromagnetic process, a propagator for each internal line of the Feynman diagram (each line not connected directly to the outside world) enters the probability amplitude. See Feynman diagram, Quantum electrodynamics, Quantum field theory, Quantum mechanics

Feynman diagrams for scattering processesenlarge picture
Feynman diagrams for scattering processes
McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.


(quantum mechanics)
The probability amplitude for a particle to move or propagate to some new point of space and time when its amplitude at some point of origination is known.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
A close examination of the previous calculations strongly suggests that the PV theory, which envisions a vacuum space pervaded by a degenerate collection of Planck-particle cores, provides a fundamental explanation for the Huygens principle and the scattering associated with the quantum-electro-dynamic propagator formalism.
(i) Use the coarse propagator G to obtain rough numerical approximations at all the time interval points [T.sub.n], that is, [C.sup.0.sub.n], n = 0, ..., N.
One of the most effective propagators I've used, powered entirely by natural and renewable energy, is an empty compost bag turned inside out, so the heat-absorbing black side faces out.
The propagator is the unique linear operator P of [C.sup.K-L] into [C.sup.L] such that
The wavy line with the tag Al stands for the "soft" photon propagator [D.sup.Al] in Eq.
Similarly, the Van Vleck propagator provides a map from which it's possible to calculate and predict the future course of any disturbance introduced into a system, whether a room or a molecule.
There are positives and negatives when it comes to propagators. They are convenient and you can set seeds off in your kitchen or greenhouse and have greater control over their germination.
Mark Phillips, prosecuting at Birmingham Crown Court, said when police raided Raymond's home at Woodend Road, Erdington, officers found 16 large cannabis plants being grown in tents in two bedrooms and 21 baby plants in a propagator.
| Sow seeds of tomatoes in a heated propagator or on a warm windowsill to grow on outdoors when all danger of frost is over.
Summer bedding plants can be sown under a heated propagator, or in the greenhouse.
Start off greenhouse crops such as tomatoes and peppers either on a windowsill indoors or in a heated propagator.
You'll have more choice of what to grow if you have a greenhouse heater or at least a heated propagator to get tender veg off to a good start.