Axion quality from superconformal dynamics

Abstract We discuss a possibility that a superconformal dynamics induces the emergence of a global U ( 1 ) PQ symmetry to solve the strong CP problem through the axion. Fields spontaneously breaking the U ( 1 ) PQ symmetry couple to new quarks charged under the ordinary color S U ( 3 ) C and a new S U ( N ) gauge group. The theory flows into an IR fixed point where the U ( 1 ) PQ breaking fields hold a large anomalous dimension leading to the suppression of U ( 1 ) PQ -violating higher dimensional operators. The spontaneous breaking of the U ( 1 ) PQ makes the new quarks massive. The U ( 1 ) PQ symmetry is anomalous under the S U ( 3 ) C but not under the S U ( N ) so that the axion couples to only the color S U ( 3 ) C and the usual axion potential is generated. We also comment on a model that the U ( 1 ) PQ breaking fields are realized as meson superfields in a new supersymmetric QCD.