2011/07/31 by Zohar Komargodski, Adam Schwimmer · 3 citations
Physics and Astronomy · #hep-th
paper · pdf · doi:10.1007/jhep12(2011)099
24 pages, 4 figures. v2: references added and minor corrections
arxiv created 2011/08/22 · arxiv updated 2015/05/28
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. Unitarity of the S-matrix results in a monotonically decreasing function that interpolates between the Euler anomalies in the ultraviolet and the infrared, thereby establishing the a-theorem.