Study of $B_c^{+}\to \ddot{I}{‡}_c\ddot{I}{€}^{+}$ decays

Abstract

A study of $B_c^{+}\to \ddot{I}{‡}_c\ddot{I}{€}^{+}$ decays is reported using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9fb${}^{-1}$. The decay $B_c^{+}\to \ddot{I}{‡}_{c2}\ddot{I}{€}^{+}$ is observed for the first time, with a significance exceeding seven standard deviations. The relative branching fraction with respect to the $B_c^{+}\to J/\ddot{I}ˆ\ddot{I}{€}^{+}$ decay is measured to be $$\frac{{\mathcal{B}}_{B_c^{+}\to \ddot{I}{‡}_{c2}\ddot{I}{€}^{+}}}{{\mathcal{B}}_{B_c^{+}\to J/\ddot{I}ˆ\ddot{I}{€}^{+}}}=0.37\pm 0.06\pm 0.02\pm 0.01,$$ where the first uncertainty is statistical, the second is systematic, and the third is due to the knowledge of the $\ddot{I}{‡}_c\to J/\ddot{I}ˆ{\hat{I}}^3$ branching fraction. No significant $B_c^{+}\to \ddot{I}{‡}_{c1}\ddot{I}{€}^{+}$ signal is observed and an upper limit for the relative branching fraction for the $B_c^{+}\to \ddot{I}{‡}_{c1}\ddot{I}{€}^{+}$ and $B_c^{+}\to \ddot{I}{‡}_{c2}\ddot{I}{€}^{+}$ decays of $$\frac{{\mathcal{B}}_{B_c^{+}\to \ddot{I}{‡}_{c1}\ddot{I}{€}^{+}}}{{\mathcal{B}}_{B_c^{+}\to \ddot{I}{‡}_{c2}\ddot{I}{€}^{+}}}<0.49$$ is set at the 90\% confidence level.

30 pages, 5 figures, All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-039.html (LHCb public pages)