Hayrapetyan, A.Tumasyan, A.Adam, W.Andrejkovic, J. W.Bergauer, T.Chatterjee, S.Damanakis, K.2026-04-252026-04-2520252470-00102470-0029https://doi.org/10.1103/PhysRevD.111.L051102https://hdl.handle.net/11486/8426A 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/openAccessArticle11110.1103/PhysRevD.111.L0511022-s2.0-105027261496Q1WOS:001639642700001Q10000-0001-8333-43020000-0002-8087-31990000-0003-1124-84500000-0001-5328-448X0000-0003-1609-35150000-0003-3548-02620000-0003-2831-6982