Measurement of the ratio of branching fractions $\mathcal{B}(B_c^{+}\to J/\ddot{I}ˆ\ddot{I}{„}^{+}\hat{I}{½}_{\ddot{I}}„)/\mathcal{B}(B_c^{+}\to J/\ddot{I}ˆ\hat{I}{¼}^{+}\hat{I}{½}_{\hat{I}}¼)$

LHCb collaboration, R. Aaij, M. Abdelfatah +1121

A measurement of the ratio of semileptonic branching fractions $\mathcal{R}(J\ddot{I}ˆ)$, defined as $\mathcal{R}(J/ψ) \equiv \mathcal{B}(B_c^+ \to J/ψτ^+ ν_τ)/\mathcal{B}(B_c^+ \to…