Weak and Strong Coupling
In a quantum field theory with a dimensionless coupling constant g, if g ≪ 1 (g is much smaller than one) then the theory is said to be weakly coupled. In this case it is well described by an expansion in powers of g, called perturbation theory. If the coupling constant is of order one or larger, the theory is said to be strongly coupled. An example of the latter is the hadronic theory of strong interactions (which is why it is called strong in the first place). In such a case non-perturbative methods have to be used to investigate the theory.
Read more about this topic: Coupling Constant
Famous quotes containing the words weak, strong and/or coupling:
“Necessity makes women very weak or very strong, and pent-up rivers are sometimes dangerous. Look to it!”
—Mary Worthington, U.S. women’s magazine contributor. The Lily, p. 183 ( November 1856)
“The great constitutional corrective in the hands of the people against usurpation of power, or corruption by their agents is the right of suffrage; and this when used with calmness and deliberation will prove strong enough.”
—Andrew Jackson (1767–1845)
“The time of the seasons and the constellations
The time of milking and the time of harvest
The time of the coupling of man and woman
And that of beasts. Feet rising and falling.
Eating and drinking. Dung and death.”
—T.S. (Thomas Stearns)