Axion from high-quality accidental Peccei-Quinn symmetry

Abstract

We propose two models where a U(1) Peccei-Quinn (PQ) global symmetry arises accidentally and is respected up to high-dimensional operators, so that the axion solution to the strong CP problem is successful even in the presence of Planck-suppressed operators. One model is SU(N) gauge interactions with fermions in the fundamental and a scalar in the symmetric. The axion arises from spontaneous symmetry breaking to SO(N), that confines at a lower energy scale. Axion quality in the model needs N=>10. SO bound states and possibly monopoles provide extra Dark Matter (DM) candidates beyond the axion. In the second model, the scalar is in the anti-symmetric: SU(N) broken to Sp(N) needs even N=>20. The cosmological DM abundance, consisting of axions and/or super-heavy relics, can be reproduced if the PQ symmetry is broken before inflation (Boltzmann-suppressed production of super-heavy relics) or after (super-heavy relics in thermal equilibrium get partially diluted by dark glue-ball decays)

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