A new calculation of semi-exclusive axion-like particle production at the LHC

We present a new calculation of axion-like particle (ALP) production in the semi-exclusive photon-initiated (PI) channel, that is either with intact outgoing protons or rapidity gaps present in the final state, and with no colour flow between the colliding LHC protons. This is the first full treatment of this process, accounting for both the possibility of proton dissociation and the survival factor probability of no additional proton-proton interactions, including its kinematic and process dependence. We present the expected event yields in the case that either one or both protons are required to be registered in the forward proton detectors installed in association with ATLAS and CMS. We find that this process can be sensitive to currently unprobed regions of ALP mass and ALP-photon coupling, in particular in the intermediate mass region. Our calculation is provided in the publicly available SuperChic 4 Monte Carlo (MC) generator, and can be passed to a general purpose MC for showering and hadronization of the final state.