Measurements of the branching fraction ratio $\mathcal{B}(\ddot{\mathcal{I}}•\to \hat{\mathcal{I}}{¼}^{+}\hat{\mathcal{I}}{¼}^{-})/\mathcal{B}(\ddot{\mathcal{I}}•\to e^{+}{e}^{-})$ with charm meson decays

Abstract

Measurements of the branching fraction ratio $\mathcal{B}(\ddot{\mathcal{I}}•\to \hat{\mathcal{I}}{¼}^{+}\hat{\mathcal{I}}{¼}^{-})/\mathcal{B}(\ddot{\mathcal{I}}•\to e^{+}{e}^{-})$ with $D_s^{+}\to \ddot{I}{€}^{+}\ddot{I}•$ and $D^{+}\to \ddot{I}{€}^{+}\ddot{I}•$ decays, denoted $R_{\ddot{I}•\ddot{I}€}^s$ and $R_{\ddot{I}•\ddot{I}€}^d$, are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4${\mathrm{fb}}^{-1}$ of $pp$ collision data collected with the LHCb experiment. The branching fractions are normalised with respect to the $B^{+}\to K^{+}J/\ddot{I}ˆ(\to e^{+}{e}^{-})$ and $B^{+}\to K^{+}J/\ddot{I}ˆ(\to \hat{I}{¼}^{+}\hat{I}{¼}^{-})$ decay modes. The combination of the results yields $$R_{\ddot{I}•\ddot{I}€}=1.022\pm 0.012(\mathrm{stat})\pm 0.048(\mathrm{syst}).$$ The result is compatible with previous measurements of the $\ddot{I}•\to {\ell }^{+}{\ell }^{-}$ branching fractions and predictions based on the Standard Model.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-038.html (LHCb public pages)