Measurements of Lepton Flavor Universality in $${B_{c}^{+}}$$ Meson Decays

The CMS experiment results on $$R(J/\psi)=\mathcal{B}(B_{c}^{+}\to J/\psi\tau^{+}\nu_{\tau})/\mathcal{B}(B_{c}^{+}\to J/\psi\mu^{+}\nu_{\mu})$$ lepton flavor universality observable are reported using two channels of reconstruction of the $$\tau$$ lepton: $$\tau^{+}\rightarrow\mu^{+}\nu_{\mu}\bar{\nu_{\tau}}$$ (leptonic) and $$\tau^{+}\to\pi^{+}\pi^{-}\pi^{+}(+\pi^{0})\bar{\nu_{\tau}}$$ (hadronic). These measurements use 13 TeV proton–proton collision data from the LHC Run 2. The results are consistent with the predictions of the Standard Model.