A High Quality Composite Axion

Abstract

The strong CP problem is a compelling motivation for physics beyond the Standard Model. The most popular solutions invoke a global Peccei-Quinn symmetry, but are challenged by quantum gravitational corrections which are thought to be incompatible with global symmetries, arguing that realistic theories contain additional structure. We explore a construction in which the Peccei-Quinn symmetry is protected to arbitrary order by virtue of a supersymmetric, confining $SU(N{)}_L\times SU(N)\times SU(N{)}_R\times U(1{)}_X$ product gauge group, achieving $\bar{\theta }<10^{-11}$ for an $SU(5)$ model with $f_a\lesssim 3\times 10^{11}$ GeV. This construction leads to low energy predictions such as a $U(1{)}_X$ gauge symmetry, and for $X=B-L$ engineers a naturally order ~TeV value for the $\mu$ parameter of the MSSM.

17 pages, 2 figures, 3 tables