Proposed Inclusive Dark Photon Search at LHCb

We propose an inclusive search for dark photons A′ at the LHCb experiment based on both prompt and displaced dimuon resonances. Because the couplings of the dark photon are inherited from the photon via kinetic mixing, the dark photon A′→μ+μ- rate can be directly inferred from the off-shell photon γ∗→μ+μ- rate, making this a fully data-driven search. For run 3 of the LHC, we estimate that LHCb will have sensitivity to large regions of the unexplored dark-photon parameter space, especially in the 210-520 MeV and 10-40 GeV mass ranges. This search leverages the excellent invariant-mass and vertex resolution of LHCb, along with its unique particle-identification and real-time data-analysis capabilities.