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The Feynman diagrams are much easier to keep track of than "old-fashioned" terms, because the old-fashioned way treats the particle and antiparticle contributions as separate. Each Feynman diagram is the sum of exponentially many old-fashioned terms, because each internal line can separately represent either a particle or an antiparticle.
In the Stückelberg–Feynman interpretation, pair annihilation is the same process as pair production: Møller scattering: electron-electron scattering Bhabha scattering: electron-positron scattering Penguin diagram: a quark changes flavor via a W or Z loop Tadpole diagram: One loop diagram with one external leg Self-interaction or oyster diagram
Compton scattering (or the Compton effect) is the quantum theory of high frequency photons scattering following an interaction with a charged particle, usually an electron. Specifically, when the photon hits electrons, it releases loosely bound electrons from the outer valence shells of atoms or molecules.
Incidentally, the name given to this process of a photon interacting with an electron in this way is Compton scattering. [citation needed] There is an infinite number of other intermediate "virtual" processes in which more and more photons are absorbed and/or emitted. For each of these processes, a Feynman diagram could be drawn describing it.
A Feynman diagram of scattering between two electrons by emission of a virtual photon. Electromagnetic waves are one of the best known and most commonly encountered forms of radiation that undergo scattering. [16] Scattering of light and radio waves (especially in radar) is particularly important.
Compute Feynman diagrams, in which divergent terms will depend on Λ. Then, define δ Z, δ m, and δ λ such that Feynman diagrams for the counterterms will exactly cancel the divergent terms in the normal Feynman diagrams when the limit Λ → ∞ is taken. In this way, meaningful finite quantities are obtained. [1]: 323–326
In quantum electrodynamics, there are two tree-level Feynman diagrams describing the process: a t-channel diagram in which the electrons exchange a photon and a similar u-channel diagram. Crossing symmetry , one of the tricks often used to evaluate Feynman diagrams, in this case implies that Møller scattering should have the same cross section ...
In both cases, the perturbative calculation of the S-matrix leads to Feynman diagrams. In scattering theory, the S-matrix is an operator mapping free particle in-states to free particle out-states (scattering channels) in the Heisenberg picture. This is very useful because often we cannot describe the interaction (at least, not the most ...