Aad, G.Abbott, B.Abeling, K.Abicht, N. J.Abidi, S. H.Aboulhorma, A.Çetin, Serkant Ali2024-05-192024-05-1920232470-00102470-0029https://doi.org10.1103/PhysRevD.108.092007https://hdl.handle.net/20.500.12713/5829A search for a new pseudoscalar a-boson produced in events with a top-quark pair, where the a-boson decays into a pair of muons, is performed using root s=13 TeV pp collision data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 fb(-1). The search targets the final state where only one top quark decays to an electron or muon, resulting in a signature with three leptons e mu mu and mu mu mu. No significant excess of events above the Standard Model expectation is observed and upper limits are set on two signal models: pp -> tta and pp -> tt with t -> H(perpendicular to)b, H-perpendicular to -> W(perpendicular to)a, where a ->mu mu, in the mass ranges 15 GeV<72 GeV and 120 GeV <= m(H +/-)<= 160 GeV.eninfo:eu-repo/semantics/openAccessPlus PlusArticle1089WOS:0011254316000012-s2.0-85181462527N/A10.1103/PhysRevD.108.092007Q1