Hayrapetyan, A.Tumasyan, A.Adam, W.Andrejkovic, J. W.Bergauer, T.Chatterjee, S.Makarenko, V.2025-04-132025-04-1320252470-00102470-0029https://doi.org/10.1103/PhysRevD.111.L051102Fernández Ramos, Juan Pablo/0000-0002-0122-313X; Van Putte, Senne/0000-0003-1559-3606; Erice Cid, Carlos Francisco/0000-0002-6469-3200; Saidmakhamadov, Nosir/0000-0002-7460-5972; Battilana, Carlo/0000-0002-3753-3068; Consuegra Roiguez, Sana/0000-0002-1383-1837; Palencia Cortezon, Jose Enrique/0000-0001-8264-0287; Makarenko, Inna/0000-0002-8553-4508; Hajahmad, Vael/0000-0003-1491-0446; Ribeiro Lopes, Beatriz/0000-0003-0823-447X; Bols, Emil Sørensen/0000-0002-8564-8732; Eimanis, Karlis/0000-0003-0972-5641; Thachayath Sugunan, Aravind/0000-0001-6545-0350; D'Hondt, Jorgen/0000-0002-9598-6241; Delcourt, Martin/0000-0001-8206-1787; De Souza Lemos, Dener/0000-0003-1982-8978; Tavernier, Stefaan/0000-0002-6792-9522; Ruiz, Jose/0000-0002-3306-0363; Pereira, Miguel/0000-0003-4296-7028; Figueiredo, Diego/0000-0003-2514-6930; Calderón Tazón, Alicia/0000-0002-7205-2040; Noll, Dennis Daniel Nick/0000-0002-0176-2360; Agicevic, Marko/0000-0003-1967-6783; Battilana, Carlo/0000-0002-3753-3068; D'Hondt, Jorgen/0000-0002-9598-6241; Jaramillo Gallego, Johny/0000-0003-3885-6608; Giacomo, Bolini/0000-0001-5490-605X; Richards, Alexander/0000-0002-9265-3679; Painesis, Haris/0000-0001-5061-7031A measurement of the ratio of branching fractions R(J/psi) = B(B-c(+) -> J/psi tau(+)nu(tau))/B(B-c(+) -> J/psi mu(+)nu(mu)) in the J/psi -> mu(+)mu(-), tau(+) -> mu(+)nu(mu)(nu) over bar (tau) decay channel is presented. This measurement uses a sample of proton-proton collision data collected at a center-of-mass energy of 13 TeV by the CMS experiment in 2018, corresponding to an integrated luminosity of 59.7 fb(-1). The measured ratio, R(J/psi) = 0.17(-0.17)(+0.18) (stat)(+0.21)(-0.22) (syst)(+0.19)(-0.18) (theo) = 0.17 +/- 0.33, agrees with the value of 0.2582 +/- 0.0038 predicted by the standard model, which assumes lepton flavor universality. By testing lepton flavor universality, this measurement is a probe of new physics using B-c(+) mesons, which are currently only produced at the LHC.eninfo:eu-repo/semantics/openAccessArticle10.1103/PhysRevD.111.L0511022-s2.0-105027261496