Search for axion-like particles using nuclear targets in the GlueX detector

We report on the results of the first search for the production of axion-like particles (ALP) via Primakoff production on nuclear targets using the GlueX detector. This search uses an integrated luminosity of 100 pb⁻¹·nucleon on a ¹²C target, and explores the mass region of 200 < m_a < 450 MeV via the decay X → γγ. This mass range is between the π⁰ and η masses, which enables the use of the measured η production rate to obtain absolute bounds on the ALP production with reduced sensitivity to experimental luminosity and detection efficiency. We find no evidence for an ALP, consistent with previous searches in the quoted mass range, and present limits on the coupling on the scale of O(1 TeV). We further find that the ALP production limit we obtain is hindered by the peaking structure of the non-target-related dominant backgrounds, and comment on how that can be improved in future higher-statistics dedicated measurements.