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Description
A search for long-lived particles decaying into an oppositely charged lepton pair, mumu, ee, emu, is presented with a requirement that candidate leptons form a vertex within the inner tracking volume of ATLAS, displaced from the primary pp interaction region. The analysis uses the 140 fb^-1 of Run II data collected at 13 TeV by the ATLAS Experiment in 2015-2018. The results of the analysis are interpreted in the context of two models, together producing generic detection efficiencies for resonances with decay lengths (cτ) of 10-1000 mm decaying into a dilepton pair with masses between 0.1-2.2 TeV. The first model is a generic pair-produced Z′ from a new heavy scalar (S) with the Z′ decaying to lepton pairs or pairs of fermionic dark matter. The second is an R-parity violating supersymmetric model in which the lightest neutralino decays into ℓ+ℓ′−ν (ℓ,ℓ′= e, μ) with a finite lifetime. The neutralinos can be produced via the decay of pairs of gluinos or a variety of electroweak modes with heavier neutralinos and/or charginos.
