High-quality composite Pati-Salam axion

We present a composite QCD axion model where the Peccei-Quinn symmetry emerges as a high-quality, accidental symmetry. The axion potential is only modified by eight-fermion, dimension-12 operators, which if present at the Planck scale, allow for axion dark matter from misalignment while solving the strong C P problem. The model is an SU ( N c ) gauge theory with ten flavors where the Pati-Salam unified subgroup SO ( 6 ) × SO ( 4 ) ⊂ SU ( 10 ) L and Sp ( 10 ) ⊂ SU ( 10 ) R are weakly gauged. The dynamics breaks SU ( 10 ) L × SU ( 10 ) R → SU ( 10 ) V and the weakly gauged groups to U ( 3 ) × U ( 2 ) ⊃ SU ( 3 ) c × SU ( 2 ) L × U ( 1 ) Y , with the QCD axion identified as one of the Nambu-Goldstone bosons. This axion has a relatively large coupling to photons while a residual θ ¯ eff may be just below the current limit on the neutron electric dipole moment. If the dimension-12 operators are present near the grand unified theory scale, they can cause domain wall networks to decay, allowing for axion dark matter even for the postinflationary scenario.