Top Secrets: Long-Lived ALPs in Top Production

We investigate the discovery potential for long-lived particles produced in association with a top-antitop quark pair at the (High-Luminosity) LHC. Compared to inclusive searches for a displaced vertex, top-associated signals offer new trigger options and an extra handle to suppress background. We design a search strategy for a displaced di-muon vertex in the tracking detectors, in association with a reconstructed top-antitop pair. For axion-like particles with masses above the di-muon threshold, we find that the (High-Luminosity) LHC can probe effective top-quark couplings as small as \(|c_{tt}|/f_a = 0.03(0.002)/\)TeV and proper decay lengths as long as \(20(300)\) m, assuming a cross section of \(1\) fb, with data corresponding to an integrated luminosity of 150 fb\(^{-1}\) (3 ab\(^{-1}\)). Our predictions suggest that searches for top-associated displaced di-muons will explore new terrain in the current sensitivity gap between searches for prompt di-muons and missing energy.