Probing Variant Axion Models at LHC

We study collider implications of variant axion models which naturally avoid the cosmological domain wall problem. We find that in such models the branching ratio of $h\to \gamma \gamma$ can be enhanced by a factor of 5 up to 30 as compared with the standard model prediction. The $h\to \gamma \gamma$ process is therefore a promising channel to discover a light Higgs boson at the LHC and to probe the Peccei-Quinn charge assignment of the standard model fields from Yukawa interactions.