A measure of the strength of interaction between two particles, or between a particle and a field.
- ‘But its predictions for the coupling constants - the constants that describe the strengths of the strong, weak and electromagnetic interactions - were wrong.’
- ‘For electromagnetism, the coupling constant is called the fine structure constant a and is formed by the electron charge, Planck's constant and the speed of light.’
- ‘Newton's constant is the coupling constant for the gravitational force, for example.’
- ‘That's an important detail, because the size of the gravitational coupling constant is what determines the distance scale of quantum gravity.’
- ‘As I mentioned, the coupling constant of string theory is not really a constant at all, and in many respects it is very similar to the compactification moduli.’