Feynman Diagram -- from Eric Weisstein's World of Physics

In order to visualize and describe quantum electrodynamical interactions, physicist Richard P. Feynman

introduced an ingenious schematic form of drawing now called a Feynman diagram. In such a diagram, all particles are represented by lines, with straight lines representing fermions and wavy lines representing bosons (except for the Higgs boson, which is usually represented by a dashed line, and gluons, which are usually represented by loops).

Particles entering or leaving a Feynman diagram correspond to real particles, while intermediate lines represent virtual particles. Real particles must satisfy the energy-momentum relation

. A Feynman diagram can be transcribed to a complex amplitude using the Feynman rules.

The diagram illustrated above represents the interaction of two electrons. Each electron is represented by a straight line, which exchange a (virtual) photon and then repel one other.

Berestetskii, V. B.; Lifschitz, E. M.; and Pitaevskii, L. P. Quantum Electrodynamics, 2nd ed. Oxford, England: Pergamon Press, 1982.

Feynman, R. P. "Space-Time Approach to Quantum Electrodynamics." Phys. Rev. 76, 769-789, 1949.

Feynman, R. P. QED: The Strange Theory of Light and Matter. Princeton, NJ: Princeton University Press, 1985.

Griffiths, D. Introduction to Elementary Particles. New York: Wiley, 1987.

Johnson, G. W. and Lapidus, M. L. The Feynman Integral and Feynman's Operational Calculus. Oxford, England: Oxford University Press, 2000.

Kane, G. The Particle Garden. Reading, MA: Addison-Wesley, p. 169, 1995.

Mattuck, R. D. A Guide to Feynman Diagrams in the Many-Body Problem, 2nd ed. New York: Dover, 1992.

Weisstein, E. W. "Books about Feyman Diagrams." http://www.ericweisstein.com/encyclopedias/books/FeynmanDiagrams.html.