Scale Invariance
If the beta functions of a quantum field theory vanish, usually at particular values of the coupling parameters, then the theory is said to be scale-invariant. Almost all scale-invariant QFTs are also conformally invariant. The study of such theories is conformal field theory.
The coupling parameters of a quantum field theory can run even if the corresponding classical field theory is scale-invariant. In this case, the non-zero beta function tells us that the classical scale invariance is anomalous.
Read more about this topic: Beta Function (physics)
Famous quotes containing the word scale:
“I have spent all my life under a Communist regime, and I will tell you that a society without any objective legal scale is a terrible one indeed. But a society with no other scale but the legal one is not quite worthy of man either.”
—Alexander Solzhenitsyn (b. 1918)