Dynamics of Superconformal Axion: Quality and Scalegenesis

Abstract

We explore a dynamical mechanism to realize the emergence of a global $U(1{)}_{\mathrm{PQ}}$ symmetry and its spontaneous breaking at an intermediate scale for an axion solution to the strong CP problem. Such a dynamics is provided by a new supersymmetric QCD near the middle of conformal window that couples to fields spontaneously breaking the $U(1{)}_{\mathrm{PQ}}$ symmetry. A large anomalous dimension of the $U(1{)}_{\mathrm{PQ}}$ breaking fields leads to the suppression of explicit $U(1{)}_{\mathrm{PQ}}$-violating higher dimensional operators. The $U(1{)}_{\mathrm{PQ}}$ breaking vacuum is generated at a scale hierarchically smaller than the Planck scale by a non-perturbative effect. The $U(1{)}_{\mathrm{PQ}}$ breaking drives the conformal breaking, and all the new quarks become massive. The axion potential is generated by the ordinary color $SU(3{)}_C$ effect as the $U(1{)}_{\mathrm{PQ}}$ symmetry is only anomalous under the $SU(3{)}_C$. The saxion direction is stabilized by supersymmetry breaking and cosmologically harmless.

8 pages, 3 figures