Probing ALPs at the CERN Gamma Factory

The aim of the proposed CERN Gamma Factory is to produce ≈1017 photons per second with energies up to 400 MeV. The photon beam intensity is expected to be a factor of O(107)$\mathcal {O}(10^7)$ larger than that of the presently available photon beams in the MeV energy range. In this work, its potential to probe physics beyond the Standard Model is explored. In particular, searches for axion like particles (ALPs) with dominant couplings to photons are discussed and various production scenarios—fixed target, photon–photon collision, and conversion by a magnetic field—and detection schemes considered—via decay to photons or back‐conversion. It is found that the Gamma Factory in a fixed target mode can probe ALPs with mass ma≲O(100MeV)$m_a \lesssim \mathcal {O}(100\,\mathrm{MeV})$ and decay constants larger than 107 GeV, improving by an order of magnitude the discovery potential of previous beam dump experiments.