%0 Journal Article %T Search for a new pseudoscalar decaying into a pair of muons in events with a top-quark pair at √s=13 TeV with the ATLAS detector %A ATLAS Collaboration (Aad, G. et al %A Aikot, A. %A Amos, K. R. %A Aparisi Pozo, J. A. %A Bailey, A. J. %A Bouchhar, N. %A Cabrera Urban, S. %A Cantero, J. %A Cardillo, F. %A Castillo Gimenez, V. %A Chitishvili, M. %A Costa, M. J. %A Didenko %A Escobar, C. %A Fiorini, L. %A Fullana Torregrosa, E. %A Fuster, J. %A Garcia, C. %A Garcia Navarro, J. E. %A Gomez Delegido, A. J. %A Gonzalez de la Hoz, S. %A Gonzalvo Rodriguez, G. R. %A Guerrero Rojas, J. G. R. %A Lacasta, C. %A Marti-Garcia, S. %A Martinez Agullo, P. %A Miralles Lopez, M. %A Mitsou, V. A. %A Monsonis Romero, L. %A Moreno Llacer, M. %A Munoz Perez, D. %A Navarro-Gonzalez, J. %A Poveda, J. %A Prades Ibañez, A. %A Rubio Jimenez, A. %A Ruiz-Martinez, A. %A Sabatini, P. %A Salt, J. %A Sanchez Sebastian, V. %A Sayago Galvan, I. %A Senthilkumar, V. %A Soldevila, U. %A Sanchez, J. %A Torro Pastor, E. %A Valero, A. %A Valiente Moreno, E. %A Valls Ferrer, J. A. %A Varriale, L. %A Villaplana Perez, M. %A Vos, M. %J Physical Review D %D 2023 %V 108 %N 9 %I Amer Physical Soc %@ 2470-0010 %G English %F ATLASCollaborationAad_etal2023 %O WOS:001125431600001 %O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=5913), last updated on Tue, 06 Feb 2024 17:08:32 +0000 %X A 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 μμand μμmu. 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