Hayrapetyan, A.Tumasyan, A.Adam, W.Andrejkovic, J. W.Bergauer, T.Chatterjee, S.Damanakis, K.2026-04-252026-04-2520251029-8479https://doi.org/10.1007/JHEP02(2025)036https://hdl.handle.net/11486/8149A search for long-lived heavy neutral leptons (HNLs) using proton-proton collision data corresponding to an integrated luminosity of 138 fb(-1) collected at root s = 13TeV with the CMS detector at the CERN LHC is presented. Events are selected with a charged lepton originating from the primary vertex associated with the proton-proton interaction, as well as a second charged lepton and a hadronic jet associated with a secondary vertex that corresponds to the semileptonic decay of a long-lived HNL. No excess of events above the standard model expectation is observed. Exclusion limits at 95% confidence level are evaluated for HNLs that mix with electron and/or muon neutrinos. Limits are presented in the mass range of 1-16.5 GeV, with excluded square mixing parameter values reaching as low as 2 x 10(-7). For masses above 11 GeV, the presented limits exceed all previous results in the semileptonic decay channel, and for some of the considered scenarios are the strongest to date.eninfo:eu-repo/semantics/openAccessBeyond Standard ModelHadron-Hadron ScatteringArticle210.1007/JHEP02(2025)0362-s2.0-105001150339Q1WOS:001426114300001Q10000-0002-7366-42250000-0001-5328-448X0000-0002-2153-15190000-0001-6242-73310000-0002-0113-68290000-0003-2510-50390000-0002-8724-9604