Test of lepton flavor universality in semileptonic B${}_{\text{c}}^{+}$ meson decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV

CMS Collaboration

A measurement of the ratio of branching fractions $R$(J/$\psi$) = $\mathcal{B}$(B${}_{\text{c}}^{+}$ $\to$ J/$\psi$${\tau }^{+}{\nu }_{\tau }$) / $\mathcal{B}$(B${}_{\text{c}}^{+}$ $\to$ J/$\psi$${\mu }^{+}{\nu }_{\mu }$) in the J/$\psi$ $\…