Conformal or confining -- results from lattice gauge theory for higher-representation gauge theories

Abstract

We have calculated the running coupling in SU(2), SU(3), and SU(4) gauge theories to see whether they have infrared fixed points. An infrared fixed point means no confinement: It means that the long-distance physics is conformal, without a mass scale and indeed without a particle spectrum. All these theories run slowly in perturbation theory, so a nonperturbative determination is interesting.

Comments: 8 pages, 8 figures, talk given at Quark Confinement and the Hadron Spectrum X, Munich, October 2012