On Renormalization Group Flows in Four Dimensions

Understand

We discuss some general aspects of renormalization group flows in four dimensions.

• Every such flow can be reinterpreted in terms of a spontaneously broken conformal symmetry.
• We analyze in detail the consequences of trace anomalies for the effective action of the Nambu-Goldstone boson of broken conformal symmetry.
• While the c-anomaly is algebraically trivial, the a-anomaly is "non-Abelian," and leads to a positive-definite universal contribution to the S-matrix of 2->2 dilaton scattering.