Search for photoproduction of axion-like particles at GlueX

We present a search for axion-like particles, $a$, produced in photon-proton collisions at a center-of-mass energy of approximately 4 GeV, focusing on the scenario where the $a$-gluon coupling is dominant. The search uses $a\to \gamma \gamma$ and $a\to {\pi }^{+}{\pi }^{-}{\pi }^0$ decays, and a data sample corresponding to an integrated luminosity of 168 pb${}^{-1}$ collected with the GlueX detector. The search for $a\to \gamma \gamma$ decays is performed in the mass range of $180<m_a<480$ MeV, while the search for $a\to {\pi }^{+}{\pi }^{-}{\pi }^0$ decays explores the $600<m_a<720$ MeV region. No evidence for a signal is found, and 90% confidence-level exclusion limits are placed on the $a$-gluon coupling strength. These constraints are the most stringent to date over much of the mass ranges considered.