Aad, G.Abbott, B.Abbott, D. C.Abeling, K.Abidi, S. H.Aboulhorma, A.Çetin, Serkant Ali2024-05-192024-05-1920230031-90071079-7114https://doi.org10.1103/PhysRevLett.131.061803https://hdl.handle.net/20.500.12713/5861A search for a long-lived, heavy neutral lepton (N) in 139 fb(-1) of vs = 13 TeV pp collision data collected by the ATLAS detector at the Large Hadron Collider is reported. The N is produced via W ?N mu or W -Ne and decays into two charged leptons and a neutrino, forming a displaced vertex. The N mass is used to discriminate between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the N with the left-handed neutrino states for the N mass range 3 GeV < m(N) < 15 GeV. For the first time, limits are given for both single-flavor and multiflavor mixing scenarios motivated by neutrino flavor oscillation results for both the normal and inverted neutrino-mass hierarchies.eninfo:eu-repo/semantics/openAccessDark-MatterMassNeutrinosSymmetryVmsmArticle131637625051WOS:0010639731000012-s2.0-85173626178N/A10.1103/PhysRevLett.131.061803Q1